QST 1928-11: Vol 12 Iss 11

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—* obeie ENTIRELY TO AMATEUR, RADIO PUBLIZHED ZINCE (915 BY THE AMERICAN RADIO RELAY LEAGUE ING New Short-Wave keceiers for 1929 CF ower eo t & SYS a ay SSSR OG ES RARER ESEE ESTAS SES PLOSGHAIRESSRsSehaszegsze te OP eo MEPERSE TSS — soan< eons BSS ARSRSRE eB Full Details IN THIS ISSUE | € NOV. 1928 35

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»- QUALITY ~ AMPLIFIER TRANSFORMERS The General Radio Company has a.- ways been identitied with audio-fre- quency transformer design. It was th first Company t ipply closed cor: audio-frequency trans ners. The new Type 585 and Type 541 ¢reups represen the latest efforts of t! Company and are intended for those desiring the ut- most in quality reproduct 4 ‘ & ouTPuT TRANSFORMER ENERAL RADIO 585 Amplifier Transformer reece . « « OSD 85 Amplifier Transformers particularly for those de- est in transformer design. f adequate quantities of Type 541-B Push-Pull Transformer as a core material precau- : overload are no longer in the case of nickel alloy In the Type 541 Push-Pul!l! Trans- electrical characteristics of formers three types are supplied. The Transformers are listed be- Type 541-A Push-Pull Input Trans- former has a flat frequency characteris- tic from 100 to 10,000-cycles, dropping to Specifications, about 75% of the maximum at 30-cycles. a Syl The Type 541-B and Type 541-C are out- 2000 © 000 Ol put transformers for use with magnetic hea ac and dynamic speakers respectively. The I:2 1:3.5 Type 541-A and Type 541-C Transform- aA b aA ers are similar in appearance to the Type 585 Amplifier Transformer. Sold _ in ?¢ pairs only. ' . Type 541-A and Type 541-B Push-Pull (sé neral Radio Co. Amplifier Transformers (for Standard Speaker) $25.00 St., . . Cambridge, Mass. Type 541-A and Type 541-C Push-Pull 7 ss Amplifier Transformers (for Dynamic innan St., San Francisco, Cal. Speaker) $25.00 o Bulletin No. 931 will be sent on request

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NOVEMBER 1928 NUMBER 11 Lditorials Standard Frequency Transmissions from W9XI High Frequency Receivers for the Coming Yea ; Ross A. Hull By Clair Foster Frequency Stability by Magnetostriction Osciilato: By Harold IP. Westman Some Su-vestions for 1929 By Il. M. Walleze \ 28-Megucycle Cr : ‘ontrolled Transmitt Ly Howard Allan ‘hinn “Now We're in the rr By Wallace S| Wiggins Odd Jcbs By G. F. Lamkin 160-Meter Low-Power Transmitte: By George B. Hart Experimenting With Bypass Condense: ‘ By John F. Roeder Experimenters’ Section Re The Northwestern Division Conventior Another Way of Playing an Old Prank Sume Radio Uses of Lamp Bank Standard Frequency Transmissions ill Heard New yndence Department Frequency Station ment of Ownership \ weWw Condenser rransmitting Hint Hamads QRAs Index of Advertisers QST is published monthly by The American Radio Relay League, Inc., at Hartford, Conn., U. 8. A. Official Organ of the A.R.R.L. and the International Amateur Radio Union Kenneth B. Warner (Secretary, A.R.R.L.), *, Cheyney Beekley, Editor-in-Chief and Business Manager Managing Editor and Advertising Manager Harold P. Westman, Ross A. Hull, David H. Houghton, Technical Editor Associate Technical Editor Circulation Manager scription rte in United States and Possessions, Canada. and a ountriesin the American Fostal Union, $2.50 per ves sid Single copies, 25 cents. Foreign countries notin American Po Union, $5.00 per year, postpaid. Remittances should international postal or express money order or bank draft negotiable in the U. 8. and for an equivalent amount in U. S. funds. entered as second-class matter May 29,1919, at the nost office : ‘onnecticut, under the act of March 8. 1879. Accept- ince for mailing at special rate of postage provided for in section }. Act of October 3. 1917, authorized September 9. 1922. Additional entry as second-class matter, acceptable at svecial rate of postage provided for above, at Springfield, Mass., 1uthorized Sevtember 17, i Copyright 1928 by the American Padio Relay League, Inc. Title registered at United States Patent Office Member of the Radio Magazine Publishers’ Association.

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‘ - juisite. President AM PERCY MAXIM Drawer 2102, Hartford, Conn. Vice-President LES H. STEWART David's, Pa. General Manager H. K. RUSSELL Mail Blidg., Toronto, Ont. ntic Division ENE C. WOODRUFF W. Fairmount Ave., College, Pa. entral Division ‘LYDE E. DARR Ave., Highland Park, Detroit, Mich. 4 esident -e-President ecre tary Treasurer nder the laws of Connecticut. nunications Manager DIRECTORS Dakota Division C. M. JANSKY, JR. Dept. of Elec. Eng., U. of M., Minneapolis, Minn. Delta Division BENJ. F. PAINTER 424 Hamilton Nat’] Bank Bldgz.. Chattanooga, Tenn. Hudson Division DR. LAWRENCE J. DUNN 80 Hanson Place Brookiyn, N. Y. Midwest Division PORTER H. QUINBY 817 Lauderman Building, St. Louis, Mo. New England Division DR. ELLIOTT A. WHITE Dartmouth College, Hanover, N. H. Northwestern Division K. W. WEINGARTEN 3219 No. 24th St., Tacoma, Wash. OFFICERS The American Radio Relay League The American Radio Relay League, Inc., is a non-commercial association of radio amateurs, bonded for the promotion of interest in amateur radio communication and experimentation, for the relay- ing of messages by radio, for the advancement of the radio art and * the public welfare, for the representation of the radio amateur in legislative matters, and for the maintenance of fraternalism and a high standard of conduct. It is an incorporated association without capital stock, chartered Its affairs are governed by a Board f Directors, elected every two years by the general membership. The fficers are elected or appointed by the Directors. ymmercial and no one commercially engaged in the manufacture, sale rental of radio apparatus is eligible to membership on its board. “Of, by and for the amateur”, it numbers within its ranks prac- ically every worth-while amateur in the world and has a history of glorious achievement as the standard-bearer in amateur affairs. Inquiries regarding membership are solicited. erest in amateur radio is the only essential qualification; ownership a transmitting station and knowledge of the code are not prere- Correspondence should be addressed to the Secretary. The League is non- A bona fide in- Pacific Division ALLEN H. BABCOCK 65 Market St., Southern Pacific Co., San Francisco Roanoke Division W. TREDWAY GRAVELY Box 245, Danville, Va. Rocky Mountain Division PAUL M. SEGAL Box 1771 Denver, Colo. Southeastern Division HARRY F. DOBRS Harry F. Dobbs, Inc. 245 »pring St., N. W., Atlanta, Ga. West Gulf Division FRANK M. CORLETT 2515 Catherine St., Dallas, Tex. HrraAM Percy Maxim, Hartford,Conn. Cuas. H. Stewart, St. David’s, Pa. KENNETH B. WARNER, Hartford, Conn. ArtHuR A. HEBERT, Hartford, Conn. F. Epwarp HAnpy, Hartford, Conn. {ENERAL CORRESPONDENCE TO THE EXECUTIVE HEADQUARTERS AT HARTFORD, CONN L____ =z = = ser In thi: sis! We Vir Th wit na’ An na\ ap) for am Na na’ Isl ric am his an nu ca hu chi NI du 7 wa He wi col tin at re me th to of tel vis or of ne m te st de he

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EDITORIALS hurricane or flood, offer the radio amateur his great opportunity for service. He has never been found wanting. In many years no community in distress in this country has been without valiant as- sistance from amateur radio. The recent West Indian hurricane was no exception. When this storm hit Porto Rico and the Virgin Islands, ham radio was on the job. The normal communication of these people with the mainland is by navy radio but the navy stations went out with the storm. Amateur radio to the fore! The San Juan naval station got on the air with improvised apparatus, operating in the amateur band for quick contact, and got it in a hurry- amateurs promptly tied them up with the Navy Department at Washington. The naval station at St- Thomas, in the Virgin Islands, similarly was wrecked by the hur- ricane, but one of the operators there was an amateur and promptly got on the air with his ham station, np4AAN (now K4AAN), and in short order, through the assistance of numerous amateurs, was in direct communi- cation with NAA. Not only that, but this humble amateur station then proceeded to change to a naval frequency and became NBB, succeeding to the call as well as the duties of the wrecked naval station. Up to a few short months ago amateur operation was not permitted in the Virgin Islands. Here was ample demonstration of its worth, with the Governor of the Islands in direct communication with official Washington at a time when it was most important. The am- ateurs concerned in these activities have received letters of thanks and public com- mendation by the Navy Department. With ample warning, this hurricane found the amateurs of unhappy Florida mobilized to receive it. Most of the amateur stations of Florida were on the job, with spare bat- teries laid by and everything set for a long vigil. Innumerable stations share the hon- ors of that black week. Many of them kept their communities informed on the progress of the hurricane and supplied them with news when wires went out. Much public message traffic was handled. Other ama- teur stations, in the region where the storm struck, had more serious duties, for they were the only links between cities filled with death and suffering and a nation waiting to help. Of these stations, 4AFC at Palm T IMES of community disaster, as from Beach was the star performer, and it dis- charged its duties in full keeping with the traditions of amateur radio and in a way to make the old heart well up in admiration. The station was operated by Ralph Hollis, and Forrest Dana of 4AGR. Dana is a civil engineer, Hollis a driver for the Fire De- partment, where his station was located. When there were definite signs that the hurricane would hit Palm Beach, these two men went out at 1:30 a.m., hunted up a dealer and bought a set of “B” batteries for emergency power and borrowed some stor- age batteries, and prepared themselves for the worst. It came. The antenna went, and it seemed the building would too. Risky as it was to go outside, they had to abandon their station; but during a short lull they returned and retrived the apparatus, found another location at the other end of the building, and under the most adverse and dangerous conditions managed to get an antenna up and signals on the air. From Monday to Thursday of that eventful week that station was continuously on the air. It did a noble job exchanging vital messages with many amateur stations and report- ing the scene at Palm Beach to the outside world. The War Department net control station, WVA at Washington, was on the air looking for Florida stations, and with the assistance of other amateurs was hooked up with 4AFC. By this means the first reports to the American Red Cross were made, starting the relief machinery of that organization, and by the same channel the word was conveyed that brought Army blankets, cots and supplies for the stricken area from Atlanta. The Red cross and the town of Palm Beach have expressed their thanks for the amateur service. The Army, as the branch of our government directly concerned with relief measures in emergencies (the basic idea of the Army-Amateur Affiliation) issued a public statement from which the following is quoted: “Messrs. Hollis and Dana realized the urgent need for outside communication and established it, cling- ing to their self-imposed task with a purposeful tenacity worth of highest praise. For three days these two men stayed at their instruments, disregarding personal safety and interests until the regular chan- nels of electrical communication with the outside world were restored. Mr. Dana lost his home, his automo- bile and all personal effects in the storm. Both men ate what food where and when it could be received ~ tone slept in a bed during their self-appointed vigil

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OST ral Gibbs, Chief Signal Officer sent them the following mes- WVA at the conclusion of the job: ed been a pleasure for the Army radio work a schedule with your station emergency in Florida and it is we discontinue this schedule. Regu- ling the operation of the War De- tation WVA prevent us from com- mmercial companies. Reports from Telecraph Company and subsequent 1 here show that the Western Union : is now able to handle your traf- the case the Army must sign off and yu two men. You are to be com- r untiring effort and loyal devotion have so well expressed during ys and we shall always remember well performed.” Indian hurricane is “one more It has brought the amateur to the attention of the public. newspaper editorials of praise ird Frequency Transmis- sions from W9XL ION W9XL is a special station ng one of three portions of ld Medal Station,” WCCO- ‘WI at Anoka, Minnesota. WCCO 1 as a broadcast station, W9XL tandard frequency station and general amateur station. The tters have independent equip- antennas but a common power Through arrangements made by insingh of the Official Frequency mmittee of the Experimenters’ \.R.R.L., W9XL is operated on regularly announced in QST. The perating the station is done with- by Assistant Chief Engineer IeCartney, with the assistance of Smith and Ivan H. Anderson also f of WCCO. guarantee of accuracy is made ervice, it is the aim of the staff an accuracy of 1/10 of 1%, materially better than can be held equency meters. The frequencies ired by means of standards which especially standardized for this the Bureau of Standards. percentage of tone modulation ed so that the signal is distinctive quickly recognizable. that this service has been ren- he past is no guarantee of its on indefinitely in the future. It pon whether the response received warrant the amount of work and olved in maintaining this service NOVEMBER, 1£28 and an increased recognition of amateur value by many agencies of importance in our national existence. In such tragedies of American life as the Vermont and Mississip- pi River floods, the two Florida hurricanes, the Illinois tornado, the Santa Barbara earthquake, amateur radio has fully demon- strated that it is of the highest utilitarian service to the community and the country at large. We amateurs are now expected to render this service when other agencies fail. A.R.R.L. Headquarters knows that A.R.R.L. members will regard this as a sacred trust; that, without rules and formal organization, every man can be counted upon to get on the air when his neighborhood needs him and do a clean-cut job in the good old A.R.R.L. way—to the continued glory of amateur radio! K. B. W to all amateurs. If you take advantage of this service, please acknowledge that you are doing so by notifying the Experi- menters’ Section, A.R.R.L., 1711 Park Street, Hartford, Conn. You may use ordi- nary stationery or special blanks may be obtained from the above address. A number of these blanks has been gathered and as the number grows we will gradually gain a unique and accurate record of transmis- sion phenomena possible with no other station. Schedules for November Schedule “A” Schedule “B”" Central Frequency Central Frequency Standard in ke. Standard in ke Time (PM) Time (PM) ~ 8:00 3 3:00 39.090 :12 12 29,000 8:24 8 :36 748 700 :12 724 24 28.000 736 14.400 18 14,300 700 14,200 713 14,100 :24 14,000 are Ko ww Division of time 4 minutes—QST QST QST de WOXL W9XL W9XI 3 Minutes—Series of letter ‘“‘d’’ with the dash about 5 seconds long and broken every half minute for station call letters. 1 minute —Freq — ke. 4 minutes—Time allowed to change to next frequency Dates of transmission November Schedule December Schedule ~ 2nd “—" 9th lith — 14th 16th _ 28th 30th — All O.F.S. should use these transmissions to keep their frequency meter calibrations within the required limits of accuracy. It will be appreciated if you will send us a report on your reception of these signals. —H. P. W. a | oe ee, ee. ~_ ~-£- Hh wae OF

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NOVEMBER, 1928 OST High-Frequency Receivers for the Coming Year Incorporating Thoroughly Practical and Satisfying Selectivity, Open Scales. and a New Ease in Handling By Ross A. Hull* Technical this article The A.R.R.L. of receivers, and in tained P in tests of the hours, when on found a case where we were willing to admit top of each other’. Its sensitivity has been heard has been of loud speaker strength; and reduced to comfortable head-phone control at minimum. Mr. Hull has new covered enable every amateur to reported soon 4-tube model described in this coast prepare for 1929 Development Program Mr. Hull reports the very gratifying actical selectivity for 1929 has been secured; it this article, in the activity is great and the without reluctance equally most Australasian volume only by disconnecting antenna and setting It is, we honestly believe, a the fields of transmitting, with its attention to the question resulta which have been at- the reach of every amateur. the 7000-kce. band in the early evening interference most intense, we have not that the signals were exactly ‘‘on practically every American signal the phones volume- has now turned is within pleasing, signals twenty feet from real “‘bear-cat’’. receiving effort and measuring. His articles minimum Further developments wiil be Ed:tor HE short-wave receiver has always throttle control or left-hand tuning that he been a subject on which two or more amateurs could argue for indefinite veriods. may have been using in his successful out- fit. It is, furthermore, for this same rea- son that we do not expect Indeed the subject has such potential- ities for dis- cussion that the individual amateur, un- aided, can readily stir up a debate with- in himself and cogitate into the night upon the details of his next outfit. The receiver, unlike the oth- er more inert any of the three __—receiv- ers, to be de- scribed, to ex- cite the com- plete approval of any ama- teur. We do trust, however. that they will be accepted as examples supplied (as in previous apparatus evolved by the Technical De- velopment Pro- apparatus, be- ing so con- stantly under the demand of provided with plug-in _ coverage on any a_ knob-twist- fier highly peaked at 1000 ing operator, 1s ceiver is asplendid com- fort, if it works well, or a great curse if it operates poorly. There are few half- measures. It is, perhaps, for this reason that the ama- teur, as a general rule, is so fixed in his ideas on the subject and so willing to argue until the bitter end in the interests of the *Associate Technical Editor, QST. In A.R.R.L. Technical Development Program. Be ing fuil-scale tube, the midget tuning condenser. two audio Immediately in front of it it to the to tune charge THE FOUR-TUBE variable tuning condensers to give band cycles to particularly suited for To the right of the drum dial the screen-grid antenna coupling the detector and the plug-in coil can be seen grouped near To tubes and the 1,000-cycle grouped in somewhat similar fashion. ondary used in this coupling circuit is enclosed in a tube shield is the bank of required audio frequency gram) not to represent the acme of de- sign _ perfec- tion but mere- ly to illustrate the practical application of features found desirable to meet the re- quirements of the coming year. It is thought that a study of the fea- tures of each of the receivers may facilitate the evolution of an outfit with a combina- tion of desirabilities calculated by the in- dividual to represent his idea of the ideal. It is very evident, we believe, that the RECEIVER and a screen-grid audio ampli- improve selectivity, the re- the requirements of next year. the left of the drum dial the tuned coupling circuit are The Ford iqnition-coil sec- fired condensers used

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} OST NOVEMBER, 192% requirements of the present and ec + future are to differ widely in ts. It will be well, perhaps, to rief review of them. last few years the successful re- yeen one in which an oscillating tw fed an audio-frequency amplifier ») tubes. For the tuner some ‘rangement of plug-in coils has | 500 1000 1500 2000 2500 3000 3500 FREQUENCY RVE OF FREQUENCY VS. OUT- TAKEN WITH THE THREE-TUBE RECEIVER rovided by a relatively broad peak that is considered practical under With the amplifiers described, nounced peaks and greater selectivity i at will by the use of a lower-resis- tudio circuit together with a tuning con- ifficiently low capacity to enable bands to be fairly well spread dial. Since the edges of the been harmonically related, a aden ser which gave full scale any one band has_ been for all others. No particular been made on the circuits of tube except that they be so to avoid “hand-capacity” ef- permit the adjustment of regen- +}, al ut the accompaniment of too iation of tuning. Though some has been shown in the use requency amplifiers “peaked” at frequency, the amplifier usually 10st successful has been that on fay al ¢ d the greatest gain. Since the UX-222, radio-frequency has been exploited to some most of the equipment des- the constructional complica- addition of a second major tuning control have debarred the scheme from general adoption. Further, it has not been evident in practice that radio fre- quency amplification provides perceptible improvement in the range of the short- wave telegraph receiver, or in the ratio of signal to “background” noises. THE NEW REQUIREMENTS The reduction in the widths of our future bands and the add tion of most foreign sta- tions to them, make it clear at once that selectivity is likely to be one of the most important requirements of next year’s re- ceivers. It is certain that there will be many stations within a few hundred cycles of each other which, unseparable with pre- sent equipment, must be individually read- able with the new receivers. Then, the odd widths of our various bands will introduce another requirement—that of adjusting the range of the tuning unit so that each band is spread across a wide segment of the dial. As has already been explained in the Octo- ber QST, an ordinary variable condenser which tunes the new 3,500-ke. band across most of its dial would be unsuited for work on the higher-frequency bands since their entire territory would be cramped into some impossibly small slice of the con- denser range. With open tuning scales will come another desirability—something ap- proaching permanence of calibration. It will be a decided disadvantage if the tun- ing circuit, fitted with a suitably small var- iable capacity to place the limits of the band between 15 and 85 degrees of the dial, is influenced by the antenna to the extent common in most existing receivers, for it would then probably be necessary to wind and adjust the coils for the particular an- tenna available and amend them for use with any antenna of other dimensions. In present-day receivers where relatively large tuning capacities are used and in which the bands are rarely spread across the entire dial, the importance of this consideration has not been evident. And while we are remodelling our receivers we might well add to the purely “1929” requirements the ex- isting (but rarely attained) desirabilities of freedom from microphonic and_ tuning noises, and smooth regeneration control without “dead areas” or appreciable in- fluence on tuning. Then, along at the tail end we will mention the obvious require- ment that sufficient sensitivity be main- tained to enable the receiver to respond audibly to all signals which are not com- . ” pletely buried under the “background” of static and miscellaneous electrical “noises”. In examining the practicalities involved in the attainment of these desirabilities in the 1929 receiver it becomes clear at once that the prime requisite, high selectivity, is a concern of the audio-frequency amplifier. Unlike the broadcast receiver, the oscillat- ing receiver has the selectivity of its radio-

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NOVEMBER, 1928 frequency end set by the very heterodyne principle used in its operation. If it is os- cillating at a frequency 500 cycles dif- ferent from that of a c.w. transmitter with- in its range, a 500-cycle beat frequency will appear in the plate circuit of the detector; and no practicable amount of radio-fre- quency amplification would eliminate that signal or any undesired signal if its fre- quency differed from that of the oscillating receiver by a frequency within the limits of audibility. If, however, the audio fre- quency amplifier was so arranged or so equipped as to make it pass a band of frequencies only two hundred cycles wide at say 1,000 cycles, then all transmitters whose frequency differed from that of the receiver by more than 1,100 or less than 900 cycles would fail to produce signals in the output of the receiver. In other words, just so long as a group of transmitters had their frequencies separated by 200 or more cycles they could be tuned in indivi- dually at the receiver to give a beat note within the pass band of the audio amolifier, and interference between them would not result. There are few difficulties in equipping the audio-frequency end of the receiver to pro- vide such a condition, as has been shown by Bourne in his treatment of Acoustic Wave Filters’, and, as far as the field of reception is concerned, a complete solution to the problem of selectivity is available. In the specific field of amateur communica- tion, however, the solution is not nearly as complete. If the majority of amateur transmitters were 200 or more cycles apart, if their frequencies were constant and if they did not flutter, wobble and creep across territory measurable only in thou- sands of cycles, we could sit back and laugh at our problem. But such is not the case. Experiment has indicated that a receiver fitted with a band-pass filter to give it the selectivity available would cause a large percentage of present signals to be un- readable unless they were “followed” con- tinucusly with a precise vernier tuning con- trol. An almost equal number of signals probably would be entirely unreadable on account of rapid frequency wobbles and keying chirps which would, in accordance with such frequency changes, intermittently wipe the signal out of audibility. Careful observation and estimation has caused us to decide that even with the vast improvement in signal character expected in 1929 it will not be practical to carry the selectivity of the receiver to the extremes possible. Rath- er will it be desirable, it seems to us, to limit the selectivity to something of the order of that provided by the four- or three- tube receivers described, an approximate idea of which can be obtained from the response curve given in Figure 1. In such an amplifier the necessary constructional OST work and expense are far below those nec- essary for the acoustic or electric band- pass filters necessary to obtain the highest possible degree of selectivity, yet the sim- ple amplifier provided will contribute greatly to the solution of the interference problem of the immediate future. It will be partic- ularly suited also for operation with the highly selective band-pass arrangements which undoubtedly are to be used generally in the intermediate future. “PEAKED” AMPLIFIERS The method used to obtain the degree of selectivity considered desirable is none other than the ancient “peaked” or tuned amplifier which has been used for so long in some commercial and amateur stations. The scheme has been made much more ef- fective and more useful, however, by util- A CLOSE-UP SHOWING THE MOUNTING FOR THE PLUG-IN TUNING CONDENSERS The drum dial used is seen to be particularly suited for the mounting of the plug-in condensera—even if it does dwarf them in size. Two G. R. sockets mounted on a piece of hard rubber are spaced so as to receive the two pine on the condensers. One of the sockets serves to hold the assembly to the frame of the dial and at the same time makes the ground connection from the condenser to the dial and the panel. izing those characteristics of the screen- grid tube which have so limited its use as an audio frequency amplifier for the broad- cast receiver. Unlike the three-electrode tube the voltage amplification of the screen- grid tube is dependent almost entirely up- on the load impedance, and whereas there is an optimum practical value of load im- pedance for maximum voltage amplifica- Audio Frequency August, 1928. Filters and Bourne. QST. 1. “Acoustic Wave Selectivity.”" by R. B

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10 r 4 it-—— 4 TOIT WIN ait 144 ] t I Me HOP —TV 00 TTD t 3 2 a 3 “al , = NOVEMBER, of audibility. This selection of signals of one particular fre- quency makes it dif- ficult and sometimes impossible to read sta- tions with chirpy or wobbly signals but in the case of the rapidly increasing army of steady clean-cut sig- TIT mt ae 5,o— +ev HE WIRING OF THE FOUR-TUBE RECEIVER a nals the improvement in readability through = interference is at once obvious. urface of the wooden base-board is covered with thin sheet all the “gréund”’ leads are run. This construction is THE TUNER PROBLEM ng the copper on the upper surface where it introduces nsulation of components from it. s condensers. R3—6 megohm gridleak. R4—50,000-ohm dget tuning conden- sistor. fixed condenser. t below) d « onde naer by-pass condenser. audio arid conden- sdio tuning condenser t necessary) d.eak-type re- form, ey fixed filament ey fixed filament choke. ty may be had in adjusting the tickler turns due to “dead- varicd if any such ced The use of a filament rheostat is made unneces- It is, of course, possible : Though a number of licated on the diagram it should not be thought that these They merely indicate connections Ordinarily, no external ground is used suggested that the capacity of C2 be poration of a ballast resistor. tor or @ rheostat in ita place. the water-pipe variety. ‘ sub-base j the three-electrode tube, the am- available with the screen-grid nerease steadily as the load im- increased to the limits ob- practice. The tuned circuit nant frequency becomes an f a high order, permit- e, at this frequency, to provide f amplification which could cer- er be approached with any tube hree-electrode type. Hence, a ut circuit, in the plate circuit > resonating at, say, 1000 cycles, an effective and highly peaked Reduced to a thoroughly prac- by the use of the secondary of now antiquated ignition coils tance, and the elimination of reening (with some admitted performance) the arrangement in Figure 2, the amplifier operates splen- ne a high degree of amplifica- he signal is tuned to, the re- ney of the Ford coil-condenser (as can be seen from Figure 1) ne other beat notes of appreci- frequencies to very low values R5—200,000-ohm sistor for volume control. R6—8-megohm gridleak. R7—Filament ballast resistor for .75 amperes. Li, L2—Tuning inductance and tick- ler wound on plug-in coil L3—The secondary winding of a Ford ignition coil—core and primary removed. R.F.C.—Receiver-type short-wave To continue this ex- amination of the re- quirements into the field of tuning systems we find that many solu- tions are available for the problem of provid- ing a different order of tuning-capacity varia- tion for the various band widths. The method which we have found most practical so far is that built into the four-tube receiver shown. It consists merely in the provision for plug-in midzet condensers, of which there are three, each adjusted by the _ re- moval of plates to give range found necessary F.ost variable re- Frost variable re- the capacity for the bands on which they are to be used. The condensers used in this particular re- ceiver are Pilot midgets, chosen on ac- count of their satisfactory design and their particular adaptability for the process cf plate removing. In order to provide the plug-in connections, G. R. pins are fitted in the manner shown in the photograph of the coils and condensers. For the rotor con- nection a complete G. R. pin replaces the short machine screw holding the spring con- tact to the end plate. For the stator con- nection a G.R. pin, the threaded portion of which has been sawed off, is sweated to the head of one of the machine screws sup- porting the stator zssembly. To provide a mounting for the sockets into which the condenser is plugged, and to provide a readily accessible collar and set screw for the condenser shaft, a National drum dial was chosen. The exact arrangement of the hard rubber socket mounting on the frame of the dial ean be seen in the photograph. Vo Ss fm te ee crea o.cr @w 3 OO OOH OS —

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NOVEMBER, 1928 It should be pointed out, perhaps, that this is just one possible arrangement. It is to be expected that the ever resourceful am- ateur will soon evolve an alternative rig more suited to his own ideas and the ap- paratus at his disposal. The expected dif- ficulties of movement of the condenser in its mountings and destruction of the cali- bration upon removal and replacement of the condensers have not been found in prac- tice. With accurate spacing of the sockets, the G. R. pins hold the condenser with splendid rigidity, while calibra- OST 13 In operation the arrangement is beauti- fully flexible since the tuning range is con- tinuously and readily adjustable to any of the values required for the work. It is, perhaps, unnecesary to mention that this particular method is particularly useful in cases where it is not desired to rebuild an existing receiver entirely, the simple process of fitting a midget conden- ser being all that is necessary to adapt a receiver suited for the present bands for operation in the coming year. The tion is restored, when the con- denser is replaced, by the simple process of adjusting the con- denser to its maximum setting (by pressing the fingers on the edges of the rotor and stator plates) and inserting it in the collar of the dial shaft with the dial set at 100 degrees. The six- plate condenser in its original form has been found satisfac- tory for the 1.750- and 3,590-ke. bands. For the 7,000-ke. band, two rotor and one stator plates are used, while for the 14,000- and 28,000 ke. bands a single rotor and stator have been found to give satisfactory coverage. In the three-tube receiver the sliding rotor condenser, which h was described on page 13 of the aa October QST, is employed to il- for lustrate an alternative scheme. It has, in practice, also been found to be a thoroughly practi- cal solution for the problem. On account of the existence of a de- scription of the construction of the con- denser and the method of adjusting it, no further details should be necessary. A THIRD METHOD In the two-tube receiver yet another al- ternative solution is incorvorated for the purpose of illustration. In this ease the usual tuning condenser of about 50 unfds. is used as the tuning control with a 23- plate Pilot midget condenser connected in series with it and used as an adjustable series cavacity to reduce to predetermined values the capacity range of the tuning condenser proper. With the midget set at its minimum capacity the range of the tunine condenser is reduced to the point where its maximum capacity is equal to the extreme- ly small value of the two condensers in series (possible about 5 uufds.). As the capacity of the adjustable midget is in- creased the capacity range of the tun‘ng condenser is increased to the point where the midget is at its maximum. At this point the capacity range of the main con- denser w_ll be such that the resultant maxi- mum capacity is of the order of 33 pufds. A PLAN VIEW OF THE THREE-TUBE SET ee range adjustment and a ne rt year s operation The be seen to the left of the mediately behind the condenser is the Ford coil secondary of the peaked mounted on brass strips immediately behind it. tube can of a_ sliding rotor on the tuning condenser for peaked amplifier similar to make this receiver a practical one “tube-base”’ coil and detector variable condenser. Im- four-tube set amplifier. The tuning condensers across it are one slight disadvantage of the scheme is that the tuning curve of the condenser, be it straight-line-frequency or capacity, is dis- turbed. The straight-line-frequency con- denser in the receiver illustrated, for in- stance, gives a curve somewhat similar to that of a straight-line-capacity condenser when the smaller values of series conden- ser are used. With the larger values of series condenser the curve departs only slightly from that of the tuning condenser alone. In conjunction with these variable capaci- ty systems, plug-in coils of the usual type are employed. In the four-tube receiver Silver-Marshall coil forms are used. On account of the small values of tuning con- denser across the coils it will be found that their vaiues differ somewhat from those with which we have become familiar. Also, on account of the smal! frequency range to be covered, and the desirability of placing this range between 15 and 85 degrees on the dial, it will be found that the number of turns is quite critical. It is for this rea- son that ready-wound coils are not likely to be suitable for the work without the addi-

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OST turns. In order to facilitate the adjusting the coils it has been found vhile first to wind them so that the r at 85 degrees tunes them slightly lowest frequency required for the ar band. Final adjustment is then spacing one or two of the end . _UE 20'Aa RG | NOVEMBER, 1928 corporated to fulfill some of the minor re- quirements mentioned earlier in this article. In the four-tube outfit, as can be seen in Figure 2, a UX-222 is used as a coupling tube between the antenna and the detector. In order to avoid the necessity for a second tuning control the tube is arranged to op- erate from the drop across a re- sistor of 10,000 ohms connected between the antenna and the filament circuit of the receiver. A radio-frequency choke, such as that built for the purpose by National, can be used in place of this resistor if desired. To drop the filament voltage to the r cuired 3.3 volts for both th's > d 4 > +615 +135¥ ev +45V ~8 SHOWING HOW RECEIVER IS WIRED ufd. by-pass condensers. Sliding-rotor”’ uufd, by-pass condenser. uufd. audio grid condenser. ufd. audio tuning condenser (adjustable). ufd. audio grid condenser. intenna coupling condenser (see illustration) -ohm rheostat. fixed resistor. ohm fixed resistor. dleak, 2 to 4 megohms. 0-ohm Frost variable i-megohm resistor. megohm grid eak. Grid and tickler coils wound on tube -ohm resistor. the edge of the band is brought the 85-degree setting of the con- [This scheme is preferable to that ng turns since it is often found ction of a turn only could be re- m the coil without spoiling its plendid advantage of all three tun- ems used in these receivers is that give “full coverage” for the ama- they are still useful for recep- special bands and on any par- quencies between them. If it is to receive some station half way the 14,000- and 7,000-kc. bands, for the midget condenser normally 3,500-ke. work, in the four-tube would be plugged into place and 1 the 14,000-ke. coil. In the three- the rotor plate would be set at on of maximum capacity to ob- milar result, while in the two-tube midget series condenser would be placed at the setting normally work on one of the two lower-fre- ands CONSTRUCTIONAL DETAILS w let us proceed to a. description receiver in turn with the idea of the features which have been in- UX-222 and that used as audio- THE THREE-TUBE type variable condenser (see text) bases. frequency amplifier, 5- and 10- ohm Yaxley resistors are con- nected in series. A_ suitable negative grid bias is then ob- tained in each case by connect- ing the grid return to the junc- t‘on between the two resistors. The coupling tube in this par- ticular receiver is found to jus- tify its existence completely. In the first place it eliminates the influence of the antenna over the tuning of the receiver, so permitting the receiver to be calibrated for the approximate estimation of frequency and for convenience in locating known stations. In addition to this, even with its simple untuned grid circuit, it af- fords quite an appreciable radio fre- quency gain which undoubtedly is worth- while, particularly in the reception of phone, or in the reception, non-oscillating, of r.a.c. signals which ordinarily would be buried under heavier d.c. signals. Further, the coupling tube reduces radiation from the receiver to a practical minimum, The output of the UX-222 is connected directly to the grid tuning circuit of the detector, which is so provided with a fixed condenser in series with the tuning con- denser, as to isolate the coil from the fila- ment circuit in order that it may carry the plate supply to the UX-222. For the same reason the detector grid leak is not connected across the grid condenser but is carried directly to the positive filament lead. The detector circuit is otherwise arranged in quite the normal fashion, resistance con- trol of regeneration being provided on ac- count of the manner in which it operates without influencing the tuning to any ap- preciable degree. In connection with th’'s arrangement it might be pointed out that the usual half-scale setting of a 50,000-ohm variable resistor results in quite a drastic drop in voltage. With the detector oper- ated from the 22'-volt battery tap, the ac-

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NOVEMBER, 1928 OST 15 voltage reaching the detector under’ er an aluminum tube shield is inverted over

tual ‘icle. such conditions is usually of the order of the coil for the purpose of shielding. Its n in 8-10 volts. If the detector is to be operated use, however, was not found to be essential. ling at its rated voltage it is obvious that the Should it be desired to produce a sharper tor. {5-volt battery lead be used and the ticklers peak than that provided by the Ford coil cond wound accordingly to give oscillation at the it would be necessary merely to use an in- op- mid-point of the variable resistor range. ductance of lower resistance. One induc- . re peter apne ie tance used in our work (which incidentally ote THE AUDIO SYSTEM gave a peak far too sharp to be practic- the lhe output of the detector is fed to the able for general reception) consisted of iver, grid circuit of the UX-222 such audio amplifier through an audio e by transformer of the usual type. Al- lace though a broadcast-receiver trans- To former with a particularly flat fre- the quency characteristic is not neces- th's sary, the use of an Amertran or dio- equally high-grade transformer 10- will be found justified on account con- of the excellent gain provided by able it. This does not mean, however, ob- that the transformer used in any ect- existing receiver would not be equally effective in this one. In the plate circuit of the UX- 222 audio tube is the tuned circuit, par- eco aud resonating at 1,000 cycles or some unc- tors.

S- “—_ other convenient frequency, which the is responsible for the peaked am- over plification and the improved selec- so tivity of the receiver. The degree . he of amplification to be obtained nate with this tube and the sharpness re of the peak are matters governed frees almost entirely by the impedance vith provided by the tuned plate circuit Sate a at the resonant frequency. The ANOTHER VIEW OF THE THREE-TUBE RECEIVER fre- va ue of this impedance, in turn, The simple and conventional practice of screwing all ap- ’ is limited by the resistance of the paratus to the base and connecting everything with bus bar wr circuit To obtain the greatest has been adhered to la, peak and amplification, there- : he fore, it would be necessary to use 3,000 turns of 30 gauge s.s.c. wire hor. the lowest-loss inductance and cond nser “scramble”—wound in five %”—square a possible. Experiment with various forms slots turned in a wooden former 2” outside of inductance (the characteristics of the -. capacity being somewhat set by the types cted of condensers available) has shown that an the inductance of reasonably low resistance can ixed well provide a peak much in excess of that con- considered desirable for practical purposes fila- in the immediate future. The characteris- arry tic shown in Figure 1 is that obtained with the a Ford coil secondary as the inductance, .° used for the definite purpose of broadening , = 5 ak ; rai nat the peak and because of its general avail- py. 4. THE SIMPLE WIRING OF THE TWO- i ability to the amateurs of any country. Most TUBE SET ged of the coils tried tuned to about 1,000 cycles © —!-ufd. by-pass condenser. ron- by the connection of about .01 ufds. across 1—50-unfd. tuning condenser. ; ac- P 2—23-plate (approx. 100 wufd.). Pilot midget. ; them. In the four-tube receiver the bank 3—100-unfd. arid condenser. ates of Sangamo condensers comprising this tun- s—Antenna coupling condenser—two %” square ts ing capacity is mounted on two threaded ., plates about %" apart. aod rods to facilitate experiment with capaci- 8 aac Sr vo = ties of different values. The Ford coil is 21—Gridleak, 2 to 4 megohms. or mounted by inserting a wooden dowel in eee waaes Seiten - the space > , > ’ 0.1-mego m resistor. : per- th at left by _the removal of the cose .1, L32—Coils similar to those used in three-tube set. al and primary winding, and by attaching this i . dowel to the base-board with a wood-screw diameter. About .07 ufds. was found inserted through the base. In this receiv- necessary to tune this to 1000 cyles. Ex-

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NOVEMBER, 1928 Ost to be seen at the extreme left rear corner of the base are used to make all battery connections. An ordinary battery cable is led into the tube base through a hole in one side and the leads soldered to the va- rious pins. The arrangement has been found surprisingly convenient from every possible aspect, and never again will we be guilty of using a string of binding posts unnecessarily monopolizing a long strip of hakelite. We hesitate to make any mention of the performance of these receivers on account of the many factors which influ- ence it, and because of the pos- sibility of arousing expectations which may be beyond fulfillment in individual cases. We do be- Lieve, however, that these four tubes are truly worth while and that the available sensitivity, selectivity and amplification are with other forms of inductance und of great interest and value. th tube of this receiver is a anged in the normal fashion. not necessary to provide am- PHONE RECEIVER is chtained in this set with the tuning con- HE TWO-TUBE adjustable tuning range nidget condenser in series se of this methed, as described in te use to convert an existing -frequency amplifier shown receivers to be used for phone lditional to that already avail- ssential to provide a_ satis- circuit since the phones ) R COMBINATIONS FOR THREE BANDS day ; used with each te full scale rrid coila are wound -Marshall coil forms. As a rough that 6 turns are used for the turns the 7,000-ke. band The ticklers found turns being and 9 turns these escent practice a separate inductance in the dial coverage for with 20-quage > give said for band d.8.¢ turns for certain 00-ke. wire, 5 7,.000-ke. that quage almost figures dual receiveis e operated in the plate circuit 22. The enormous amplification the two audio tubes makes the lume control essential. type socket and UY tube base the tuning system for nple addition of a midget series condenser. The in this reception, text, ig in equal to any reasonable de- mands that could ever be made on them. In addition, we think that the receiver is particularly svited for the requirements of the future, having pro- vision for tuning range adjustment which would adapt it to any desired frequency band, and having an amolifier which, with simple amendment, could be given any in- creased selectivity which may be made practicable by wide improvement in the emissions of amateur stations. receiver will THE THREE-TUBE SET In the three-tube receiver, as seen in Figure 3. the antenna’ coupling tube has been eliminated and the usual capacity coupling scheme _ incorporated. This means the sacrifice of some sensitivity and an increase in the influence of the an- tenna over tuning calibration. The latter can, however, be reduced greatly by mount- ing the antenna coupl'ng condenser as close as possible to the grid of the detector tube, and by reducing its capacity to the lowest value consistent with reasonable signal strength. The importance of the place- ment of this condenser is not, we believe, fully appreciated. Experiment has shown that the connection of the condenser in the antenna lead about six inches from the tube grid terminal can_ re- sult in serious “hand-canacity” effects and a pronounced increase in the reaction of antenna changes on calibration. The tun‘ng circuit comprises the “slid- ing rotor” tyne of condenser mentioned previously, and “tube base” coils, while the audio amplifier consists of two tubes— a UX-222 and a UX-201-A arranged in the same circuit as that employed in the can be

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NOVEMBER, 1928 four-tube set. The differences in the me- chanical arrangement of the apparatus can be seen from the photographs. FOR PHONE WORK The two-tube receiver is presented chief- ly to illustrate the use of adjustable series capacity to vary the capacity range of the tuning condenser. It is also intended to il- lustrate the single stage of flat-frequency- characteristic audio amplification which will still be desirable for the reception of amateur phone or short-wave broadcasting. The circuit is shown in Figure 4. The series midget condenser is controlled by the knob in the center of the panel, its positions for the various bands being de- termined by experiment and marked on the panel, The adjustment of this condenser will be found quite critical if it is desired to restore the calibration of the main tuning condenser when a change is made from one band to another, but this process is sim- plified very greatly by noting the dial readings for the commercial crystal- controlled stations at one edge of each THE TUBE-BASE COILS USED IN THE THREE- AND TWO-TUBE RECEIVERS Both arid coils and ticklers in these coile are wound with 24-guage d.s.c. wire The numbers of turns used are as follows: Band Grid Turns 1,750 ke. 7.500 ke 7,000 ke 1 4,000 ke 6 28,000 ke. 8 Tickle r Tu) ns 49 ee $3 5 No spacing is used between turns exce;t in the grid coil for 28,000 ke. where the spacing %s 1-8". As can be seen, the 1715-ke. coil is woyed on a 2" dia- bakelite tube mounted on a tube base. meter band. Then, when the coil has been changed in moving from one band to another, it is merely necessary to set the tuning dial at the place where the “marker” station should appear and adjust the midget until it does. At this position the calibration will have been restored. In all three receivers the panels were cut from %” thick aluminum sheet. A pleas- ing finish was obtained by stripping the surface in a strong solution of washing OST soda and brushing it with a very thin coat of Du-o clear lacquer. In the construction of these three re- ceivers no attempt was made to break away from the conventional method of screwing all the gadgets on a base and connecting them together, for we have the idea that there are very few departures from this standard amateur practice which warrant the complications involved by them. In fact, in all the work a definite effort was made to avoid any departure from the simple methods of the present day unless they possessed a definite practical value. We have had at our disposal scores of un- usual circuits and arrangements, the merit of which was in their novelty, They were unused, however, because it is our opinion that the practicality of any scheme, in amateur radio, is at once questionable if it involves a sacrifice of simplicity. 2y-Strays "$5 _ One of the snootiest methods of mount- ing the League Auto Emblem we’ve run across is that of cementing the emblem to the inside of the wind-shield or rear win- dow. The scheme is to remove the eyelets from the emblem, smearing it evenly with DuPont or some other good glass cement and, when the cement has become tacky, press it firmly to the cleaned glass sur- face. Considerations of visibility make it desirable that the emblem b» located on the passenger side of the wind-shield at the lower corner though a position at the lower center of the shield also might be practical. The genius behind the scheme is Meserve of 1FL. August McCollom, 9BQW-9HS, though blind, is an ardent and successful amateur Since “1925 he has been on the air, during the summer at his home station 9BQW at Dodge City Kansas and during the re mainder of the year from 9HS at the State School for the Blind at Kansas City, Kan- sas. A CX-310 supplied from a storage battery-driven 400-volt dynamotor is used at the latter station, while at 9QW an 852 does the oscillating. R7 signals have been put into Australia with it. McCollom is able to copy signals with a typewriter but, being unable to read the typing, all traffic is handled in Braille. In this man- ner he has been able to QSR as many as forty-five messages in a week. ‘Taking it all round there is nothing unusual about my amateur activities’, says McCollom. ‘I build my sets and blow my tubes just as you fellows do.’

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OST NOVEMBER, 182% sj5BX A True ‘“‘Now-It-Can-Be-Told”’ Story that Unravels One of the Recent Mysteries of Amateur Radio By Clair Foster* 1 fellers who were so curious sj5BX, the mystery station last winter, here’s your dope. His are now back on the soil of U.S nd it’s safe to tell it. He had lit- er hoot his way out; but he’s out. In } mber, 1927, I received a long 1 Central American stamp from ed Haskell Watson. That’s his He was on an expedition. The accompanied by photos and ting his location at the bottom t voleano. This old crater was both directions and the walls in were sheer 3000 feet. The let- | also a list of the radio parts hand. He had built one short- iitter; but he hadn’t been able nybody and had about come to ion that he had been trying to the bottom of a well 3000 nd that it just couldn’t be done. ther troubles, believe me. He rigand-infested district. It was on the mountains and some nds used to stick around his t was warmer. He had reason hat some of his own helpers he gang. A guy came in on while he was building his trans- surmised that it had something his radio stuff that the natives aring about. This didn’t look gentleman who didn’t desire his to be broadcast, so he ordered H mash it up. Haskell finally m that he knew nothing about s was a scheme he was experi- for assaying minerals. This — ut of old boy; but thereafter Haskell k rper watch through the telescope rained on the only entrance to the ere was only one way to get after anyone was seen coming Haskell had an hour to hide After finishing the set and after many days to work somebody, that what he had told the no lie. er heard of Haskell before the his letter. He had been in the as, from Texas. He had been » the war but out of the game W. Carmel, California. since. Three of his friends in Texas had wised him up considerably on short-wave apparatus. In the use of a .45 pistol he needed no instruction; all he needed was practice, and he got plenty of that down in the volcano. The natives engaged in the chief industry of the district packed plenty of hardware, but, cartridges costing a dollar apiece in their money, they did no practicing—a circumstance that saved Haskell’s life on more than one occasion. He and his friend, Paul, the only other white man in the party, had plenty of ammunition. They shot wolves on the run and eagles in the air, partly for practice, largely to keep the natives in a proper frame of mind. On the whole, from things I have since learned and from things he himself has let slip, I gather that sj5BX is pretty hard-boiled. Now back to that letter. It came while Ralph Heintz, 6X BB, was spending a week- end at 6HM. If you don’t know Ralph from his accomplishments let it be said here that he is as far on the plus side of radio as your Uncle Dudley is to the negative. That im- plies a world of wisdom. Haskell’s material was passed across the table to Ralph. Ole Ralph spit on his pencil and commenced forthwith to scatter Haskell’s apparatus over a sheet of paper, doubling up on some parts to get the required values and adapt- ing others. When he had arrived at the best he could do with the parts Haskell had on hand he drew out a radiating system and specified how far it must be located from a sidewall of the crater. “Now,” he said, “send your friend this dope and I think he’ll get his signals out of that hole.” I hadn’t told him that Watson was a stranger to me, or that in advising him we might be guilty of compounding a felony. In that country no one is allowed to transmit and you can’t even get permission to listen. Haskell had said that he was signing the call DON. I told him to locate if possible a little below LP1, down among the Australians. In about three weeks I com- menced to watch for this DON, with a d.c. note from a 50-watter and dynamotor. And about that time I had to go to San Fran- cisco. Fred Roebuck, (old KFUH), there at 6ARD, said, “Say, have you heard a sta- tion signing sj5BX? Where the dickens would that be? There isn’t any such inter- mediate.” Herbert Breuer, 6JN, was with us, and we all did a lot of surmising. The next day, just as I was about to leave the — eth at eet co oe oO Om weet OA OO *n @

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had rave he was own in ked ing no ved ion. nite ion. } in eep On ned iile ek- om hat ur NOVEMBER, 1928 hotel for home, Herbert called up with, “Hi! I worked that sj5BX last night! And guess where he is. On Pablo Island, at 90 degrees West and 6 degrees South of the equator.” And told me where to look for him. When I reached home I soon found sj5BX, work- ing a Six and giving that same QRA. Also telling the Six, “Not much use sending a card, Old Man, because ships come here only about once a year. Will QSL later.” I couldn’t find any Pablo Island, or any other kind of an island, at the position named— which would be about 500 miles off the coast of Peru. Then down at our village post-office I met a man who had just been living in Peru. He had never heard of such an island. I explained what the intermediates were for, and that there was no Se such intermediate as SJ in use. fr “Oh,” he exclaimed, “now I think I can straighten you out on that. The old name for Peru was Juinan.” (I leave the pronuncia- tion to those of you who are familiar with Spanish. Those who are not would better leave it alone. It starts with a noise like blowing your soup. Or if you plead not guilty, try, it with the first note of the hoot-owl.) This man said that many of the old-timers refused to use any but the old name, and that this sj5BX was doubtless of one of the old aristocracy of Peru. So _ that straightened me out fine. And I was just pluming myself over being able to show the boys the breadth of my knowledge when I noticed among the letters I was holding in my hand one with a foreign stamp. These a ham always ovens first. “I was afraid of _ that DON eall. It sounded suspicious. So I decided to use a ham-sounding call with an intermediate that nobody could locate.” And then the mystery of Pablo Island really was solved. But after that I told many a feller why this old moss- backed Peruvian insisted upon using SJ instead of SP. Some of you who worked this station will recall that frequently there was a YL at the key. Haskell had taught her the game, and had refused to let her operate the set until she had become letter-perfect. He had done such a fine job with this pupil that he broke his own nose, for she was a dandy operator—better than Haskell. She is a relative of his by marriage, being his wife. And how she did like to bawl a feller out for sending double, or for sending slowly when he could go faster. She was the Helen Wills of the key and you didn’t have to soften your game for her! You OST U SROMISED 2 5S\. + azn fellers who worked sj5BX when she was operating will be sorry that you didn’t QSO oftener when I tell you that she is as fine looking as she is fine. It is too bad that the foto I have of her and Haskell is not sharp enough to reproduce with this story. They are both well worth looking at. Aside from the purely radio features of this tale there is enough of the dramatic and human interest in the doings at sj5BX to fill a book. Goodness knows, it is inter- esting enough to think of transmitting from the bottom of a hole 3000 feet deep. They came near to working all continents. cs] aa Vers WRKD HR Sea OR » PABLO IsLAND om qo°WEST— lo’ SoUTH Wh ISRX. R Lsines D bf} o “WW * “ j e4 THE QSL CARD OF 8jiBX Home-made, photographically, with a snap of the YL on the left and of the OM on the right these cards because he says, haif an hour, trict and for a special Haskell made only ten of “Each one we made took about and besides that’s enough for one for each dia- friend or two.” They would have done so with a little more time. For example, they would have if foA3V had been able to get them thru his QRN the night I had him on Haskell’s trail. The story of Haskell’s trip out of the crater for some dynamite that he bought from brigands who had taken it in the hold- up of a mine, and the things that happened on his return with this stuff loaded on three burros (there were three when he started) would make a thrilling tale all by itself. Or an account of the time when two bad eggs started to shoot up him and Paul one dark night just outside their camp, and ended by going to—wherever it is that assassins go. Or the time when another of these gentry tried to kill the house-servant, and had to be dissuaded permanently. Or the time when Donna and Haskell were all alone and were pounced upon by nine. This last fracas I think I must tell you about, because it is this one that ended the career of sj5BX, and you will want to know how the finish came about.

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ons had a parrot from which only semi-detachable. I think YL parrot, because it used to sit ’s knee and pull the buttons off She was devoted to amateur radio QST. Just couldn’t keep away hack, even when nobody else was here were so many nice coils and ew on. That’s why you seldom 5BX twice in exactly the same spot. operating was going on she was Ruths around the table and over tor’s shoulders. Once while QSO rry call to QRX while the parrot revived. She had got against the (TG&P, series feed) and hit for eger. The air was full of blue 1 green feathers. bright afternoon of a lazy June, this YL parrot were sitting n the porch of their little camp m of this extinct volcano, telling r whom they were going to work when all of a sudden it didn’t » darned extinct. Nine gentle- mplected on the outside and all through, appeared suddenly with vare erupting in the general the Watson family. Watson ; living a life of preparedness, tion, Donna acting as gunbearer on the loaded pistols while Has- shooting. When the smoke ired away two of the dark-com- ntlemen were dead, others were id the two Watsons were over- As to the YL parrot I am not oY I think she fainted. Haskell were roped up too mfort and cached temporarily hut to ponder on the vicissitudes The one thing that they of was that after nightfall taken out and shot. But, w that you can’t keep a good vhat happened when darkness at a faithful servant—the one n rescued when the bad egg kill him—cut the prisoners guided them out into the bush had saddled and hidden their re y , spent seven days getting out st town over a bandit-ridden and walking hours on end in ark to avoid being seen. They ng except what they had on and ey to buy two cans of sardines These sardines and three Haskell shot with a pistol were they had on this ride. And ‘ve seen of the amount of stuff can put away at a hamfest I'll picture hits you fellows in a Ost NOVEMBER, 1928 tender spot. At this town they had thought they would be safe, but they found that the news of the rumpus had preceded them and that they were being accused of murdering these men in cold blood. The prospect of being thrown into a filthy jail to await the decision of the law of a lawless land didn’t appeal. A stranger, a fellow American, gave them some money and then beat it out of town himself. They hired a Chevrolet truck and an armed guard of eight men. With these they slipped out in the night, headed for a larger town. Most of the eighteen hours of that journey was spent in pushing the Chevrolet over a trail that a jackrabbit couldn’t have traversed under his own power. Having had to bribe so many “officials,” they arrived in this town again broke. But another good American came to the rescue and they reached the coast and a ship Eventually they landed where a ham gets a square deal from his government; where 16,000 amateurs were dispossessed of their earned and rightful place on the air by the adroit maneuvering of foreign governments and a comparatively small number of money-seeking commercial interests, but at any rate a country where a ham nee:l not fear going to jail. Now as to the ethics of the situation; as to the conduct of Haskell’s ham friends who were in the know and who had kept his expedition in touch with the outside world: The American Radio Relay League will doubtless disagree with us, for A.R.R.L. is a stickler for the niceties of ham behavior. But this was not just a case of hamming for amusement. Many vital comissions were executed for sj5BX that could not have been handled thru a telegraph station and post-office six hazardous days’ ride from him; where all mail and messages were scrutinized, and even their delivery at times denied thru the ignorance and suspicion of officials. I'll say that, when two fellows and the game wife of one of them. go cn an ex- pedition that has a perfectly legitimate and laudable aim, into a country where the laws are hand-made from day to day by whatsoever brigand or grafter happens for the time being to be in control, a country so ignorant of the uses of radio that its purposes are regarded as wholly sinister. where large murders for small gains are the rule—I’ll say that the ham who had re- frained from doing his utmost to aid these people should be read out of any society where there exists a consciousness of right Adios, sj5BX. You are a fine guy and a brave gentleman. And so’s your OW. the tai sta ge’ up os¢ cal the fac cie pic wil qu ost de: tai me ing al me mi bec en ho Sta

Page 19

ught t the - and ring t of | the idn’t ican, ; out rolet men. ight, the pent that nder als,” But scue ship gets here heir the ents of but 1ee:] ; as who his rid: will » is ‘lor. ing ons ave and rom rere nes . of and ex- and the by for try its ter, are re- ese e y ht la NOVEMBER, 1928 OST Frequency Stability by Magnetostriction Oscillators By Harold P. Westman, Technical Editor ROF. G. W. PIERCE of Cruft Labora- tory at Harvard University has pub- lished a paper entitled “Magneto- striction Oscillators’”which deals with the magnetostrictive characteristics of cer- tain materials and their application to the stabilization of the frequency of oscillations generated by a tried. This article is based upon the material appearing in that paper. Like quartz plates, magnetostriction oscillators are dependent upon a mechani- cal vibration for their stability and al- though it is not possible to obtain satis- factory output at extremely high frequen- cies such as may ke obtained with the piezo-electric oscillator, it is possible that with the devolopment of suitable fre- quency multipliers that magnetostriction oscillators may some day be of extreme value in amateur work. Magnetostriction deals with mechanical deformation of cer- tain materials when they are subjected to magnetic fields either of constant or vary- ing strength. If for instance, we take a rod of nickel and subject it to a constant magnetic field of 1 gauss, we find that its length has been shortened by about one millionth. This change is extremely small because it must take place against the enormous elastic force of the material. If, however, the magnetic field is not con- stant but is made to vary in an oscillatory manner at a frequency equivalent to the resonant period of the rod, the deforma- tion of the rod will be much greater be- cause it does not then take place against the elastic force of the body but is opposed only by its viscosity or ability to yield continually when under stress. Under the varying magnetic field, the mechanical lengthening and shortening of the rod may reach a value as great as 100 times that observed with the field constant, This effect, as one would suspect, works two ways and if we stretch or compress a magnetized rod, we will find that its mag- netic field has been altered. The deforma- tion of a rod under a magnetic field may be considered as the direct effect while the change in the magnetic field due to a me- chanical deformation may be considered as the inverse effect. In order to take small effects, it is advantage of these necessary to use a l Proceedings ef the American Acade my of Arts and Sciences Vol. 638. No. 1. This publication may be obtained from the Library of the American Academy of Arts and Sciences, 28 Newbury Street, Roston. Mass.. for $.90 vacuum tube and thus obtain enough ampli- cation to allow sustained oscillations to be produced. Figure 1 gives a schematic diagram of the circuit employed. The rod is placed within two coils and rests at its center on a blunt pivot. It does not have to be critically balanced and may even be tightly clamped at the center if that is desired for any reason. One of the coils is in the grid circuit while the other is in the plate circuit, much L L, WZ 0, LZ FIGURE 1. THE CIRCUIT ARRANGEMENT FOR OBTAINING MAGNETOSTRICTION CONTROL OF FREQUENCY. The rod rests on the blunt pivot be- tween the coils. as in the split-coil Hartley arrangement. However, one of the coils is reversed so that feedback from the plate coil to the grid coil without the aid of the rod is not in the proper direction to cause oscillations to be produced. It is possible, though, un- der certain conditions to cause such a sys- tem to oscillate without the use of the rod and as this is not damaging to the stability of the arrangement, it is unnecessary to take precautions to avoid such conditions. A condenser is shunted across both the coils so that the circuit may be adjusted to have a frequency of oscillation equivalent to the period of the rod employed. Let us assume that the electrical circuit is so adjusted that it is not oscillating of its own accord (without the rod) but that if it did oscillate, it would do so at the same period as the rod. The rod is placed within the coils and the filament of the tube lighted. The plate current will increase as the filament emission becomes greater and this current flowing through the plate coil will cause a mag- netic field to be set up about the coil, This magnetic field will act upon the rod and

Page 20

OST ve deformed (either lengthened The deformation tantaneously along the entire rod travel along the rod at a definite nding upon the hardness of the is composed. When nation reaches the end of the rod thin the grid coil, the inverse ef- take place and the magnetic field ng the rod will be varied because of the rod have effect the grid coil and induce a therein which will be applied to F ti This voltage applied will be amplified and will re- hange in the plate current which I again by causing field around the through which it flows. is made to oscillate at dependent upon rr lengthwise vibration of the of which will be two factors, namely; the length and the speed at which the de- propagated along material em- material, the higher will be the * sound through it and the higher natural period of vibration. oscillations be produced, magnetized and field is superimposed up- This will result in an in- magnetization varying field is in one direction rod were not magnetized the varying field would not nerease and decrease but would increase (or decrease) » (or decrease) twice for each - than give both an increase and for each cycle which is desir- may be permanently magnet- serting them into a solenoid and y direct current through it. to the direct plate current keeping the rods permanently and when in this condition the marked so that they are rted in the same direction. nnecessary to have to remagnet- most materials will hold their n in spite of the effect of the ld in which they are operated. At steady field should be greater ials that have but little ability magnetism, the steady field from .a small permanent NOVEMBER, 1928 horseshoe magnet which is placed near the rod. It is not necessary or desirable to have the permanent magnet touch the rod and it may be located several inches from it. In Figure 2, some experimental curves taken on a rod of Nichrome are illustrated in the circuit arrangement shown in Figure 1. The upper curve shows the change in wavelength obtained for a given rotation of the tuning condenser shunted across the coils. The rod was first held to prevent it from vibrating and the curve ABCDE was obtained which indicates a change in wavelength of from 16,000 meters at 19 de- grees of the condenser dial to 19,400 meters at 30 degrees or a change of 3,400 meters for a dial rotation of 11 degrees. Next, the rod was allowed to be free to vibrate and the condenser rotated from a low reading towards maximum. The curve ABCD’E was then obtained and it will be noted that over portion indicated by D’ there is no readable change in wavelength. The condenser was then rotated from maximum towards minimum and the curve EDCB’A resulted. This shows a constant wave- length along the portion of the curve B’. After the rod has started to vibrate it is possible to vary the condenser from 18 to 30 degrees without shift'ng the wavelength. Thus, over a range of the condenser that gives a wavelength shift of 3,400 meters without the rod, there is no readable wave- length change when the rod is in vibration. It was impossible to read any shift of wavelength along the stabilized portion of the curve when a precision wavemeter was employed as the measuring device and so some other method must be used to show how much the frequency does vary. Apn- other magnetostriction oscillator was set up and a rod having a frequency of about seven times that of the rod under test was set vibrating. The seventh harmonic of the rod under test would then beat with the fundamental of the second oscillator and a change of one cycle in the test oscillator would cause a change in the beat note of seven cycles. The beat note could be meas- ured to about one cycle which would be equivalent to a shift of but one seventh of a cycle of the rod under test. As will be seen by the second curve of Figure 2, a change of the condenser from 19 to 30 de- grees with the rod vibrating causes fre quency change of only 1.5 parts in 17,000. The lower curve of Figure 2 indicates the change in plate current as the capacity across the coils is varied. As the capacity is increased from a low value, the current follows the solid line and when the reverse rotation takes place the current varies as shown by the dotted line. The jump in current of two to four milliamperes takes place as the rod starts to vibrate and the smooth tapering of current as the conden- ser to t ditis (the tric: of t Oth hig] line capi It ure! the cau pos acit giv’ the’ hig’ of sho ~ ¥ sys fre equ circ mo ma cap ing fa he fro plo pes col in the is du ere col an

Page 21

1928 r the le to e rod from urves rated igure re in ation s the event CDE re in 9 de- eters eters e to m a ‘urve ll be here The mum, 'B’A rave- 1 it is 8 to eth. that ‘ters ave- tion. t of n of was 1 so h ow An- t up bout was the the id a ator » of Pas- be rn of | be , a de- fre- 00. ites city city ‘ent rse as in kes the en- NOVEMBER, 192% ser is reduced towards 18 degrees is due to the fact that the particular circuit con- ditions caused the electrical oscillations (those not due to the rod but to the elec- trical circuit alone) to stop when the value of the condenser was less than 18 degrees. Otherwise, the characteristics shown at the higher capacity setting portion of the solid line curve would be duplicated at the lower capacity end of the dotted line. It must be remembered that in the meas- urements just cited, the capacity across the coils was varied over a wide range to cause as large a change in frequency as possible and that in actual use, the cap- acity will always be set at a value that gives the highest plate current. It will, therefore, be possible to obtain a much higher degree of precision in the resetting of the equipment than the possible error shown by the curves might indicate. ~ We may regard the operation of this system over that portion of its range where frequency stabilization takes place as being equivalent to an_ inductance-capacitance circuit in which the inductance varies enor- mously with a change in frequency. We may represent the wavelength-against- capacity curves of Figure 2 by the follow- ing equations: da=2n../La(C+C.) for the damped curve he—2ae./Le(C+C.) for the free curve from which we obtain ie L ha La Figure 3 gives the values of this ratio plotted against frequency from which it ap- pears that the change in inductance of the coil and free rod is ahout 50% for a change in frequency of less than 1/100 of 1% over ‘hat range in which the stabilizing action is operative. We may, therefore, consider that if the capacity across the coil is re- duced, the shift in frequency causes an in- crease in the inductance of the rod and coil so that the product of the inductance and capacity is almost the same as it was before the change was made. Likewise, any increase in capacity will cause a de- crease in inductance to an amount that will still compensate and the product of L x C will be nearly constant. Thus, if the rod is not used, a change in capacity of 50% will result in a frequency change of 25% whereas with the particular rod under test, this change of capacity results in a fre- quency change of but 1/100 of 1%. The comparison was made between the rod and a quartz crystal mounted in a vacuum and held in an accurately designed and carefully machined mounting. Re- peated measurements indicated that when this crystal was operated under constant conditions, which must be very carefully OST 23 checked, that an accuracy of frequency of 1/500 of 1% could be maintained. How- ever, when the circuit conditions for the crystal are changed over as great a range as indicated for the rod, the frequency of 2 FREQUENCY Mi AMP PLATE on EN SER DIVISIONS STRATING STABILIZATION OF FREQUENCY FIGURE 2. THE UPPER CURVE SdOWS THE STABILIZING EFFECT OF THE VIBRATING ROD WHEN THE ELECTRICAL CIRCUIT IS DE- TUNED AS COMPARED WITH THE ELECTRI- CAL CIRCUIT ALONE. The second curve shows ust how much the frequency does change when the electrical circuit is detuned and the rod is vibrating. This curve is equivalent to the horizontal portion of the upper curve very greatly amplified. The lower curve shows the behavior of the plate current of the tube as the rod starts to vibrate. the crystal would vary as much as 7/100 of 1%. Thus, the magnetostriction oscil- lator shows’ greater constancy’ under widely varying conditions than does the piezo-electric plate. The particular Nichrome rod under test showed a variation of 1/93 of 1% for each degree Centigrade change in temperature which is not as good performance as is obtained with the crystal, which changes between 1/200 to 1/1000 of 1% per degree Centigrade. However, by the proper choice of materials it is possible to construct rods having as good a temperature coefficient as is obtained with the crystal. In any case, it is only necessary to know the tem- perature in order that the proper correc- tion factor may be applied. The effect of temperature is not permanent and rods calibrated at a definite temperature will hold their calibration as long as they are operated at that temperature even though their temperature may have varied con- siderably in the meantime. There are various materials that may be

Page 22

u main requirements are that tl magnetostrictive effects, h quency of vibration stay con- stant f varying temperature and ree and that changes in the tings, tube lar characteristics nent currents shall cause but nge of frequency. P nd irons with various carbon suitable because the mag- net effect is very small. Pure nicl very active vibrator but its De} ion will change when the els uit is detuned. <4 | Pq |__|} 4+— —+——+4

7013 7014 REQUENCY iTIO OF THE CHANGE OF 'TTED AGAINST FREQUEN- ( ’ of nickel and iron are g | those having about £6 per nd 64 percent iron, which is a nstitution of invar and stoic sat Unfortunately, though, frequency with a change of rather high. N | other alloys of chromium, nick n are good vibrators. Per- hay | Nichrome is one of the best re easily available materials M containing 68 percent of ent of copper and small am n, silicon, manganese and ca powerful oscillator but usu res an auxiliary polarizing de f the small residual mag- and iron are strong --. Tu | may be used for qualita- tir nstration purposes and for soul ind and while they are good are not so constant in fre- qu be desirable. Such tubes n y or partly filled with lead or ty] hich will result in their’ period f 1 ing materially lowered. This Ost

NOVEMBER, 192 is due to the fact that the velocity of sound in lead is low. By this means it is possible to obtain rods of low frequency without the use of an excessive length. Composite rods may be used in order to reduce the effect of temperature upon the frequency of vibration. If a tube of nickel which has a negative temperature coeffi- cient has inserted within it a tightly fitting core of a material such as stoic metal which has a positive temperature coeffi- cient, the resultant rod may be made to be practically independent of temperature. These rods are concentrically composite. Another type of composite rod consists of three rods soldered end to end. The center section is of a material having a soefficient of one sign while the end sec tions are of a material, the coefficient of which is of the opposite sign. These ros are longitudinally composite. The frequency at which the rod will vi- brate depends upon its length and upon the material of which it is composed. The following table gives the length and fre- quency of some stoic metal rods which are 0.79 cm. in diameter. The temperature is 20 degrees Centigrade. Frequency in Cycles Leneth in Length in Meters Per Second Cm X Frequen’y ~ 10001 20.815 9081.7 14981 13.87 2977.8 20003 10.40 2080.3 24992 8.33 2081.8 29981 6.93 2977.7 The frequency values given in the above table are accurate to within 1/100 of 1%. Because the ends of the rods are not ab- solutely true, errors in their measurement may be as great as 0.1 mm. which amounts to more than 1/10 of 1% for the shorter rods. If the length of the rod is multiplied by the frequency of vibration, the constants which appear in the third column are ob- tained. The variations in these figures are L, he

" ' ICM we 1em | |

L2ecm FIGURE 4. THE ROD CONSISTS OF FIVE BEADS CONNECTED BY SECTIONS OF HALF THEIR DIAMETER All sections are of equal width. This red_ vibrates at 95,480 cycles per second. The rod may also be made to vibrate with one of the beads between the two coils and the thinner sections within the coils not greater than the allowable inaccuracy in the measurement of the length of the rods. If the constant is doubled, the vel-

of ot & of

Page 23

— ss NOVEMBER, 1928 ocity of sound in the material is obtained which for stoic metal is: V — stoic = 4160 2m/sec at 20° C. The diameter of the rods is approximately the same and as there is no progressive change in the constant it indicates that there is no appreciable end correction for the determination of velocity, Accordingly, the length of a rod to give a definite frequency can ke computed closely enough so that after having been cut in a lathe the final adjustment may be made with but a slight amount of grinding. If the grinding is carried too far so that the frequency of the rod becomes higher than the desired value, it is possible to correct this by grinding away some of the girth of the rod at its center. Th's next table gives the values for a series of Nichrome rods 0.96 cm. in dia- meter at 23° C, Frequency in Cycles Length in Length in Meters per Second Cm X Frequency 29992 8.27 2480.3 55002 7.13 2495.6 10004 6.23 2492.2 {5008 5.53 2488.9 19996 4.99 2494.8 55014 4.53 2492.1 The magnetostriction oscillator is most valuable at frequencies below 25,000 cycles per second particularly in view of the fact that the quartz crystal is OST 25 are cut. They are 1 cm. wide and 1 cm. apart. The vibrator then con- sists of 5 beads, each of which is 1 cm. long and is separated from each other by 1 cm. When the rod was placed so that one bead was within one coil and the adjacent bead within the other coil or when one bead was between the two coils, the rod vibrated at a frequency of 295,480 cycles per second. The rod is of stainless steel, the velocity of sound through it being 5,430 meters per second and the length of a vibrator to give this frequency is: Length 543,000 + 2 x 295,480 — .918 cm. This is about 10% less than the com- puted value of one of the beads standing alone when regarded as a linear vibrator. The system is resonant at other frequencies, the strongest indication being at 19,888 cycles per second. It is interesting to note that rods of large diameters may be made to vibrate at high frequencies. A thin disc 1.5 cm. in diameter and only about 2 mm. long can be made to oscillate at a frequency of about a 1,500,000 cycles per second. The disc is mounted between corks in a glass tube. Its oscillations are very feeble and are in- extremely expensive at these fre- quencies. Between 25,000 and 300,- 000 cycles the oscillators have a c common field of usefulness. The crystal oscillator has more value at frequencies above 300,000 cycles because although the magnetostric tion oscillator is active up to 2,000,- 000 cycles per second, its output is extremely feeble and it is more de- sirable to employ harmonics of lower frequency rods if points in this range are desired. Frequencies up to several millions per second may be obtained by means of such harmonics. The higher frequencies (300,000 eycles) may be obtained by three different types of rods. One method is to place very short cylinders within the plate coil with their axes parallel to the magnetic field of this coil. A second method is to use flat sheets or strips of mate- rial which are placed between the plate and grid coils and a third method is the use of a beaded rod. Fig. 4 gives some idea of the shape and position of the rod. The rod was originally 1.26 cm. in diameter and 9 em. long. Four grooves that are % the radius deep FIGURE 5. THE ‘CIRCUIT ARRANGEMENT FOR COM- PARING trolled TWO OSCILLATORS. The upper circuit is con- by a 1000-cycle rod, the frequency of which is checked by the synchronous clock in the plate circuit of the second tube. The third tube amplifies the harmonic of the 1000-cycle source that beats with the fundamental of the second rod which appears in the lower circuit. The outputs of the two circuits are coupled together through L5 and Lé and the heat difference noted an the milliammeter.

Page 24

OST by the clicks heard in the ceivers when the tuning con- ises the electrical circuit to pass resonant period of the rod, ire many uses to which these s may be put and it is possible by ne rod to obtain points over an ange of frequency. These are ob- the use of a second oscillator, the of which may be varied over its. When higher frequencies fundamental of the rod are desired, of the second oscillator may be eat with the fundamental of the iction oscillator and if addi- ts are desired they: may be ob- beating harmonics of the electr'- r against harmonics of the rod librating a frequency meter from meter is short-circuited and r the electric oscillator coil. The illator is adjusted so that its (or harmonic) is at zero beat tal harmonic (or fundamental) of the r¢ rain I tor. The frequency meter short- r switch is then opened and as re- approached by rotating the dial ter, audible beats will be heard in frequency and fall to zero A further rotation will cause beats to be heard again which once to zero. When the frequency djusted to that position giving upon each side of which audible btained, all three units are in (either at their fundamental or ic frequency), y be calibrated in the following rod vibrating at the rate of per second is employed to drive us clock. By means of weights be clamped to it and moved ther or further apart, the fre- rod can be accurately set. of one such rod could be now ra range of about 7 cycles by tne circuit-making contacts are 1 short period of time each second ichronous clock. Electrical im- ipplied each second by a standard assed through these contacts to a ker and when the ticks are heard speaker it indicates that the lock and the synchronous clock p. The number of seconds in two clocks are out of step indi- » difference between the length of of the standard clock and the the second of the motor driven eral successive intervals may be 1 an average taken from which vibration of the rod may be NOVEMBER, 1{2% The timing of the 1000-cycle rod could be made directly because the synchronous clock was designed to be driven by a 1000- cycle wave. However, if a_ higher fre- quency rod is to be calibrated it will be necessary to beat a harmonic of it against the 1000-cycle rod. The 1000-cycle rod is adjusted to zero beat with the nearest har- monic of the rod to be calibrated and the vibrations of the 1000-cycle rod checked against the standard clock. The exact fre- quency of the 1000-cycle rod may be ob- tained from which can be computed the frequency of vibration of the smaller rod. It is not necessary to depend upon the beats as heard in the telephone receiver because a d. c. milliammeter made be con- nected into the circuit and a visual indic- tion obtained. Fig. 5 shows the circuit arrangement for comparing the two rods. The motor- driven clock takes the place of the choke that would be used for coupling between the first and second amplifier stages. The second stage is used for amplifying the higher frequency harmonic of the 1000- cycle rod circuit and the small coupling condenser between its grid and the plate of the first stage tends to reduce the ampli- fication obtained on the fundamental fre- quency. <A _ radio frequency choke con- nected across the input of the grid circuit of the second stage also aids in reducing the amplification of the 1000-cycle funda- mental frequency, still allowing the h'gh frequency harmonic to be amplified. The two output circuits are coupled by means of the coils L5 and L6 and as the beat fre- quency approaches zero it will be indicated visually on the milliammeter. The motor- driven clock may therefore be used to standardize both rods at the same time. While magnetostriction oscillators may not be directly applicable for the stabiliza- tion of transmitter frequencies in the ama- teur bands, this does not indicate that they are of little or no use to the amateur. Their use in the calibration of frequency meters is extremely valuable particularly when one realizes how much cheaper it is to obtain a series of rods as compared to the cost of an equal number of quartz plates. We have already accepted frequency doublers in our crystal-controlled transmit- ters and there is no reason why we may not find it to our advantage to pick off a more remote harmonic of a magnetostriction 0s- cillator for the stabilization of our em- mitted frequency. The rod is inexpensive and extremely rugged; two factors which are decidedly important from the amateur view point.

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could onous 1000- - fre- ill be rainst od is . har- d the ecked t fre- e ob- 1 the * rod. 1 the ‘eiver con- indic- ment otor- ‘hoke ween The » the 1000- pling te of m pli- fre- con- rcuit icing eans fre- ‘ated »tor- d to e, may liza- ama- they ‘heir ters vhen s to the Ss. ency mit- not nore os- em- sive hich teur NOVEMBER, 1928 OST Some Suggestions For 1929 By H.M. AYBE you have built that new 1929 transmitter and find that the wave is not as steady as the book says it should be, or you have just re- vamped your plate supply to get a good clean-cut smooth tone but have found that it has a rattle in it. Since my daily grind takes in locating and fixing all kinds of such troubles in about all kinds of trans- mitters, it is natural that I have learned some of the kinks. Not having seen many such stunts described I want to pass a few suggestions along to add to the many excel- lent articles that have appeared in QST designed to take the hay-wire out of ama- teur radio for 1929 At the last Atlantic Division Convention at SXE I made a remark at a general argu- ment session to the effect that 1929 signals should be strictly pure d.c.! I wonder now how I got home alive and in operating con- dition! I was almost hauled down and only one brave lad backed me up—after the meeting. The cry was the hardship it would work on the amateur existing on the plunder from kid brother’s nickle bank. One al- ready had a 30-henry choke and 6 mikes and still no sign of d. c. and wanted to know how he was going to get the required 150 henrys and 300 mikes more. The answer is that either the filter or the rectifier is badly overloaded or the set very poorly adjusted. Considering the tons of good information already printed on circuit adjustment, the trouble must lie in one or both of the two items first mentioned. We have heard considerable about brute filters but little on common sense filters, as some one put it. The fellow who hangs a 30-henry choke and 10 mikes on a motor generator has more money that horse sense. I have yet to see a machine, built for radio work, that required over 3 to 5 microfarads in conjunction with a good choke of from 2 to 5 henrys providing many other things are as they should be. To begin with, the condensers must be good ones and the chokes must be large enough (talking of copper and iron) so that the current passed through them is not over 75 percent of their rating and for many of the chokes which the amateur uses the current should not exceed 50 percent of the rating. If you are using rectified a. c. be sure that the rectifier tubes are plenty large enough so that they can be run somewhat under their rating, which will result in greatly im. proved voltage regulation and among many . 597 North James Street, Hazleton, Penn. Walleze* other things the life will usually be in- creased. The same thing applies to the plate transformer which should be capable of delivering considerably more power than it is called upon for. If you want good re- gulation the chokes and transformers must be husky and it is only by good regulation that one can hope to have a signal that is not full of key chirps. Running power tubes underrated has been greatly stressed but it must be remembered that the same applies to every piece of equipment in the set. One way to check the quality of your equipment is to put a brick on the key, just as you have been running everything, and then take in a good show. When you come home, three hours later, the set most prob- ably won’t be running. Something burnt up. Throw that something out and get another that will stand up to that treatment or else cut the input until your toy “something” can handle it. Any set that can’t run half a day full tilt is hay-wire, somewhere. Perhaps you have cooked the set over- night without a fire, have everthing under- loaded and have spent much time in making fine adjustments according to the informa- tion given in QST and you still find that the would-be pde note is fine a. c. Well, quite likely you have your rectifier and filter crammed within 3” of the r. f. circuits there- by pumping plenty of r. f. into these units. Besides losing good r.f, you lose a good note because no filter and rectifier can operate properly with a lot of r.f. floating around in it. Even though nothing blows up, the filtration will be poor. Moving this equip- ment well away from the set and inserting an r.f. choke (plenty of turns on a small diameter tubing) in each supply lead may fix it. If not, quite likely your filament heating transformer is set on the same shelf as the r. f. equipment and the core iron is a little loose and hums quite a bit. The trans- former is then just bouncing around at about 120 j.p.m. (jumps per minute), the tube element jumping along with it at the same rate, especially the filament, if it is a little aged and stretched, a lead or so right in phase with them helping matters along. The result is a modulation of the radio fre- quency wave at 120 cycles plus a few high kicks thrown in for good measure by the keying relay which is probably stuck up on the frame somewhere. Set these units up on sponge rubber after firmly clamping the core of the transformer or, better still, move them out where they can’t shimmy the r.f. parts. If you are using a motor generator with-

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OST two of cement under it, the probably happens. The machine floor ditto, and the set and vell. Even though heavy rigid be used in the set the chance of good and it does not take a spoil an otherwise good note. is not too large, a bundle of under each end will fix both the signal as well as the rumble OM’s bedroom which will help geht work. tor may,be stirring up a grand mmutator which finds its way high voltage leads or, more t radiation from the machine it away or put it in a tin can get to cut some air-holes which overed with copper screening. tor generator frame and the should-.all be connected to a This may also quiet the BCL couple of pointers regarding ontrolled transmitter might Unless you are looking for .£. choke in the grid circuit of ibe should not be so constructed | period falls near that of the does, the circuit will tend to hout the aid of the crystal; an Armstrong circuit. While adjustment, the crystal will ‘requency and the output may be better, the increase in the r.f. | to the grid and consequently rystal, may be great enough to late. It should be possible to tage from the amplifier tubes rtz plate from its holder and oscillator tank condenser is ugh its entire range there tendency for the circuit to illation. If it does oscillate, re turns to the r.f. choke until ndition can be obtained. are on the question of chokes, te the transmitter with series as to reduce the amount of he choke is being called upon If there is any difference in between the series and parallel feeding, it is so slight that in it is negligible. hing applies to the use of bias- as compared with the use of variable resistors are used btained will approach so closely tained with the use of biasing t one would have to sit up about year to hear the difference, are properly adiusted. Th means a lot to the slim bank ell as in the amount of con- rk necessary. Of course, if NOVEMBER, 1928 the voltage regulation is not good, the bias may vary considerably but that cannot be blamed on anything but the power supply system. As far as the receiver is concerned, it should not be considered a disgrace or even a luxury to put a cabinet around it. The “box” won’t affect the signal providing it is constructed of good dry lumber and well treated with high grade clear varnish. Don’t smear it up with pole paint or something worse. While many claim that resistance control of regeneration does not give as good signal strength as some other m-ihcd. = & is built correctly, it will do just as well and perhaps better. Instead of trying to work with a small diameter tickler coil stuck a foot from the secondary, make it the same diameter as the secondary and put it not more than 4” away from it. Cut the tickler turns down to 2 or 3 for the higher fre- quency bands and run the detector plate voltage up to 30 or 35, if necessary. If your tuning condenser is as small as it should be and has a good vernier dial you will then have an ideal receiver with but one tuning control. The regeneration control won't change the note and you can work the de- tector tube at the point where greatest sensitivity is obtained. There will be no necessity for “edging” up on the regenera- tion control in order to hold your signal. If you insist upon two tun:ng controls put in a stage of tuned radio frequency—then sit up some more nights and figure out how much necessary gain you have obtained against all the fuss and cost. ee Strays") 3AJC had some grid leaks of the coated glass filament variety which were getting noisy after about a year’s use, Upon chemical investigation, it was found that the resistance material was germanium, a material which tends to crystalize at the end of about twelve months. The Radio Division, Department of Commerce, has appointed seven new As- sistant Radio Inspectors, with four more contemplated. The new men are receiving training at the District Supervisors’ offices and will then be placed at new branch of- fices which the Department is opening at Buffalo, Dallas, Denver, Los Angeles, Min- neapolis and Omaha. 7OK tells us that he was using the con- densers out of Ford coils for filters. The first batch he had blew at 850 volts and the second batch has been working on 750 with- out any sign of going West.

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be ily en he ell ng NOVEMBER, 1928 A 28-Megacycle Crystal-Controlled Transmitter- OST 29 By Howard Allan Chinnt URING the past few months nulXM maintained automatic transmis- sions on 28 megacycles during cer- tain periods on Saturdays and Sun- days in an effort to obtain data relating to wave propagation in this high frequency band recently opened to amateurs, and to provide those hearing the transmissions with a definite point in the frequency spectrum. The transmitter was crystal controlled and the frequency known to be 28 megacycles, within .1 of 1%. This arti- cle, describing the transmitter used, is pre- sented not because of any new or radically different features involved but rather to oratory experimentation, is not especially compact, as a permanent installation could undoubtedly be. The crystal used has a fundamental frequency of 1.75 megacycles and therefore four frequency doublers were necessary. From the circuit diagram we see that the crystal oscillator tube and the first three frequency doublers are UX-201- A tubes, Somewhat greater output can be obtained by using UX-112-A tubes in these positions, but in this particular case the UX-201-A tubes were found entirely satis- factory. The fourth frequency doubler is a UX-210 tube which provides the 28 mega- cycle voltage to excite the grids of the two THE TRANSMITTER WITH THE CRYSTAL OSCILLATOR AND FOUR FREQUENCY DOUBLERS PANEL-MOUNTED AT The crystal holder may be seen at the unit are used for the UX-210 frequency doubler condenser to tune the mounted on the shelf above the extreme right holds the circuits. The “RP” batte) 13 supply bias show the straightforward arrangement of a 28-megacycle crystal controlled transmit- ter. The procedure and circuit arrange- ments are not limited to 28 mec. operation but can be modified for operation in any waveband. The transmitter was assembled of units that were available at the time and as can be seen from the photo, is half panel and half breadboard in construction. The ap- paratus, being primarily designed for lab- -ibution Round Hills Shortwave *Contribution from the Radio Research. 1 Communication Laboratory, tElectrical setts Institute of Technology, Cambridge A, Massachu- Massa- chusetts extreme left resistors Ré and R7. and the second board has the The midget condenser hanging up in the air above the input circuit of the two 852’s horizontal arms of the 852'a The two antenna condensers. the The two coils behind this board are similar to those for THE LEFT Two slide wires behind this The first breadboard at the left holds the pair of 852’s mounted upon it. inductance is the grid tuning The neutralizing condensers are breadboard on the and meter. frequency doubler antenna inductance used in the the 10 avd &52'a. UX-852 tubes which straight amplifiers. The reason for operating the last stage as a straight amplifier and therefore neces- sitating some form of neutralization was because it was found that when tubes were used as frequency doublers they operated rather inefficiently. Thus, to obtain a given output from a tube it is necessary to oper- ate it with a considerably higher plate dis- sipation when used as a frequency doubler as compared with that when used as a straight amplifier. Since most of us run our tubes at a maximum safe plate dissipa- tion anyway, it follows that the logical way are operating as

Page 28

OST NOVEMBER, 1928 output from a given tube’ stage amplifier has the further advantage operating conditions is to that when properly adjusted, practically no traight amplifier rather than as radio frequency flows down the center tap doubler. The apparatus as_ leads to the filament or plate supply cir- up employed the last tubes as cuits. The proper point for the center-tan loublers (one of the UX-201-A leads (those going to the C minus and B r omitted) but the output was plus) would be to the exact center of the factory and the tubes ran too grid and plate inductances if everything ddition of one UX-201-A the were balanced and symmetrical. Different ige converted amplifier increased with the power. ralization ar- ised in the of interest peration § is from con- Fig. 2. shows the amplifier y without the by-pass etc., anc rid-plate _ iT THE LEFT IS THE LAST FREQUENCY DOUBLER, A UX-210 tube capa- This sowa somewhat more clearly the input circuit to the pair of 852’: P and the two neutralizing condensers. The breadboard on the right holds ated. It is the antenna tuning equipment as well as the meter. feed back capacities ircuit will oscillate. Figure the equivalent circuit in- se tubes and the _ neutral- nsers. The points P; and G ught of as representing the grid erminals of tube 1. Likewise its the grid-plate capacity of circuit can be further un- shown in Fieure 2c. Here have an ordinary capacity oints heing lettered the sam? 2b. Thus we see that if the ing ecanacities are equal to and to the grid-plate capacity ; being used, the bride¢e will be id any voltage introduced bet- ints G, and G» will have no the bridge points P, and P:. ee that in adjustment of the cir- ll expect to find the two neutral- ities about alike and equal to capacity of the tubes plus pacity due to sockets and wir- erage grid-plate canacitances ommon tubes are as follows: length leads (this should be avoided as far as possible) from the tubes to the induct- ances may cause a slight unbalancing and therefore the exact points to which the cen- ter-tap leads are connected should be found by trial. These voltage nodes may be found by using a screw-driver (or a neon tube) and locating that point on the in- ductance from which no are can be drawn. It should be noted that both inductances are “high” above ground and care must be taken to avoid shocks from the plate and grid supplies. In order to avoid any radio frequency current that does come down the center-tap leads getting into the power supply, both the B and C battery terminals are by-passed and provided with r.f. chokes. Incidentally, it might be well to suggest that if you have any sensitive r.f. meters about it is wise to remove them a considerable distance from a 28 or 56 Me. (ten- or 5-meter) transmitter. Thermo- couple meters that were thirty feet from this transmitter and had their terminals shorted have been seen to go half-way up- scale. For convenience, the first four coils, Li, ‘rid to Plate Capacity (based tube) Le, Ls, and L, were wound on bakelite tub- 10.1 ing and equinned with G. R. plugs. While 11.0 this method did not permit the use of ad- By justable taps that would have permitted ¢ 125 more efficient operation of the frequenc 19.0 doublers, it makes for simplicity and quic! 57 interchange of inductances when necessary} . = Thus the apparatus may be used with ' nding itself to easy neutraliza- crystal of any fundamental frequency ar: need cireuit used for the last proper coils quickly plugged-in. In the set-

Page 29

NOVEMBER, 192% up, as actually used, a switching arrange- ment was included to cut out or by-pass as many of the frequency doublers as was de- sired in order to make the apparatus as flexible as possible.’ This is shown in Fig. 3 The coil and condenser values used are given in Figure 1. The values for C,, Co, C; and C, are the approximate capacitance values actually used. The condensers were all National 500-uufd. receiving condensers, adjusted to these values. C; and C:; were National 150-uufd. transmitting condensers adjusted to the values indicated in the fig- ure, Cs and Cis were General Radio 15- OST A tubes was approximately 200 volts. This was obtained from the 500-volt plate sup- ply to the UX-210 by suitable resistors Re and R: It was necessary to use two re- ————— Xi Q wth ir FIG.3 sistors, and not one common one, since it was desired to key in the plate circuit of the last UX-201-A frequency doubler. If Ze mC 28 MC CRYSTAL-CONTROLLED TRANSMITTER FIG. 7 oc THE COMPLETE CIRCUIT DIAGR4M THE af + ¢ : er ’ 40v Ac CONSTANTS ARE AS GIVEN BELOW 18 d.c.c. '8 d.c.c wire on 18 d.c.c wire on ~ 32 turns of Ne. 14 turns of No. 4 turns of No 5 and L? 5 and L7— 8 turns same as LS5. 5 turns same as L5. and Li0—G.R. choke No. 379-T. Samson cholee No. 85 and C2—125 ppfds. 225 upsds. 90 upfds. and C7—75 "6—15 ppfds. '8—30 pufds. "9, 10, 11, 12, 18, 19 and 21 "12—Double spaced G.R. midget. 14, 15, 16 and 17—.006 ufds. '20—and C22—.01 ufds. Th 2 and 3—.5 megohms t—50,000 ohms. ae—os ro. R6—30,000 ohms. ?7—13,000 ohma R8&—1 ohm. > Soeopes io me %& eS >) uufds asaqeaxres WZAABRAS uufd. midget variable condensers, the latter being doubly spaced. The plate voltage applied to the UX-201- Gr wg s\e Holt XX Qe 002 ufds Capacity probably wire on 3 inch form. 3 inch form 3 inch form. 2 turns of spaced edgqewound copper 2 turns of spaced edgewound copper ribbon ribbon about upfds a common resistor were used and the plate circuit of this tube opened the voltage on the remaining 201-A tubes would rise to a dangerously high value. The plate supply for the 852 tubes was 2000 volts and was obtained from a 2000-volt generator having four commutators which permitted the use of a 500-volt tap for the first five tubes. 1. This entire unit was built over a year ago by R. L. Briggs in carrying out his thesis at Massa- ‘husetts Institute of Technolory » QST. p. 19, March 1928

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OST ts of the 852’s and the 210 a ten volt a.c. source while happened to be lighted from a ery although they might just been arranged for operation filament voltage for the 210 ped from ten volts to seven and the series resistors Rs, two be- 4 ; na wm = ~ fue ? ; in each side of the line in center tap would not be un- Small resistors of various values r such purposes may be obtained | manufacturers. » facilitate tuning of the trans- NOVEMBER, 1928 quency doublers are in tune, including the 210 stage. With the meter coupled to the coil in the plate circuit of the UX-210 al} the condensers can then be slightly read- justed for a maximum current in this tank circuit. If desired, the antenna can be coupled to this plate circuit and the ap- paratus used as a low-power transmitter. The bias on the 210 tube and the 852’s is such that when the key is up no excita- tion voltage is being fed to the grids of these tubes, thus their plate current is prac- tically zero. As the r.f. grid excitation voltage is increased, the plate current in- creases and this also serves as an indication of optimum adjustment. Thus if we watch the plate current of the 210 tube as the first four condensers are adjusted we find it to be at maximum (the key being down) when they are all in tune. This value, in- cidentally, will be in the order of 50 mil- liamperes with the grid and plate voltages indicated. The plate voltage is now supplied to the 852’s. The neutraliz- ing condensers are then adjusted with the key up (no r.f. excita- tion voltage on_ the grids of the 852’s) un- til there is no self-os- cillation of the tubes when the plate and grid circuits are in tune. The key is then closed and with the thermo-couple meter VIEW OF THE FREQUENCY DOULBLERS AND CRYSTAL OSCILLATORS at the right and the » cut out one or more of the three 125-milliampere thermo-couple thermo-galvanometer, shorted rle three-inch turn of wire was ingle turn is first coupled to e in the plate circuit of the lator tube and the condenser the indication is at maximum. should be kept as loose as rder that the effect of the upling coil on the tuning of a minimum. The meter is d to the coil in the plate circuit frequency doubler and this cir- d until a maximum indication btained. In order to make cer- is tank circuit is tuned to the nie of the crystal a frequency- ld be coupled to the coil and the hecked. It is quite possible with ls to tune this tank circuit to fourth harmonic and to ob- weak tank circuit current. This is repeated until all .the fre- porcelain-based knife frequency doublers. coupled very loosely to the plate inductance of the last stage, the cir- cuit is adjusted to resonance. The antenna is then coupled and the antenna condensers adjusted for maximum antenna current. Readjustments should then be made throughout the entire circuit in order to secure maximum antenna current. The antenna employed for these tests was a horizontal half-wave antenna with a 5/4 wavelength feeder, the construction and operation of which has been mentioned.’ See Fig. 4. The actual length of the antenna flat- top was 17 feet and the feeder length 42.5 feet. The antenna current with this par- ticular installation was .8 ampere with 500 watts input to the last stage of the amplifier. To adopt the transmitter for operation with crystals of other fundamental fre- quencies or in other wave-bands it is mere ly necessary to eliminate or add frequency doublers as necessary, by switching, choose the proper coils and adjust the condensers.

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NOVEMBER, 1928 OST “Now We're in the Air!” By Wallace S. Wiggins* HE title of this story is not intended to refer to a movie of some months ago, but rather to the rapidly grow- ing “air-mindedness” of amateur radio. Taking a brief squint over our glorious past, we see the real “ham” radio, as it really is, taking part in various enterprises of world note, from Green!and’s icy shores to the South Pole with iyrd. We’ve been in the air before, y’understand, but not to such a degree that we could be called members of the air family. We won't forget WNP as a starter for giving the explorer confidence in ham radio. And we remember with a heartache our old iriend NERK, the Shenandoah. She was the first to give “wings” to the ham. From then on, ham radio began to get acclimated to its angelic element by means of various nota ble flights, all the way up to KHAB, the Southern Cross, which winged its way from Oakland, California, to Australia. Of course, radio, technically speaking has been “in the air” for some time, but much of it wasn’t ham radio. They've used sets in planes for army and navy tactics for quite a while. Many other civilian in- stallations have been made in planes, bu most of them smacked of the “commercial. The others were ham sets from either an engineering standpoint (good ones, we mean!), or they involved the co6dperation of the “gang” to such an extent that it was almost strictly a ham undertaking. The latest stunt by the Knights (for short) of the A. R. R. L., was ene in con nection with the 1928 National Air Ruces. at the municipal airport in Los Angeles, from September 8th to 16th inclusive. The Amateur Radio Research Club of the “C'ty of the Angels,” affiliated with the A.R.R.L., provided the star performers for the circus, and even though it was a “ground job,” it rated as high in importance as any other official function during the races. It was a great success, it gained favor and friends galore, and above ali it paved the way for the “bigger and better” chances for amateur radio to continue to prove its worth. It’s about time I told you about the stunt. I am not following the style cf the news story, with the important facts in the first paragraph or “lead,” for the sim- ple reason that the technicalities involved are familiar to every amateur *perator with any experience at all, and because *W6CHZ it is the significance .of the thing rather than the thing itself that is important. It started this way. During the air meet, which consisted of the finishes of trans- continental races, army and navy demon- strations of airplane tactics, hundreds of stunts by civilians in planes and ’chutes, a THE HARD-WORKING CREW FROM THE A.R.R.C. OF LOS ANGELES WHO PUT OVER THE JOB. Left to right: Wm. Breuer, W6BZR; Chas Lundhlad, WeCcYX; Chas A. Hill, W6BRO-W6éDRO; Robt. Par- h, W6QF-W6PS-W6XC; Chas. A. Nichols, W6ASM ; Bert Fox, WéDY and other remember, each day. and ten-mile steel and a Pylon Num- mammoth airplane exposition, things too numerous even to there were several local The races were around five- courses marked by _ pylons, or towers, with checkerboard “wind sock” flying at the top. ber 1 was on the field. near the judges’ stand. Pylons Numbers 2, 3, and 4 were located at distances of one, two, and three miles from Pylon Number 1. The first three pylons marked the five-mile course, while all pylons were used in the ten-mile course. Observers were stationed at each pylon. It was their duty to see that contestants did not “cut corners,” or take parts of the pylon along with them, or drop souvenirs of the plane along the course, or do a hun- dred other things they might do and maybe some things nobody had ever thought of before. Then the judges had to know, at any instant, just where any plane was and how many laps it had completed. You’ve it—reliable communication _ be- tween pylons and the judges’ stand was necessary. Enter our hero, with a vacuum tube in one hand and a key in the other. His pockets are filled with spare parts. The Junior Chamber of Commerce of Los Angeles had charge of the Committeee on Communications. Our western friend, M. E. McCreery, W6LJ, was on the committee. Whenever something big is happening or (Continucd on Page 60) races s des guessed

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y OST NOVEMBER, 1928 Odd Jobs G. F. Lampkin* of cutting a circle in a panel for decent results, some a special tool. Certainly the d of drilling and filing around ference of the circle is both labor- roductive of indifferent results. m one to ten inches in diameter, of thicknesses up to one half e depicted in Figure 1 will give or be able to obtain it. Only half the length of the tool will be needed for the circle cut- ter; any greater length would be in the way. To shorten the tool, clamp it in a heavy vise, half projecting above the jaws, and give the projection a sharp blow. Grind one end of the tool smooth.’ About %” of the other end should be ground similar to the shape in Fig. 2. The front of the tool is beveled back, to give a rak- ing cut, so that the tool will not ——+| gra) or chatter. The width of the cutting part is made as small as_ possible, consistent Wo. 34 dril- § tap —F == Aa Big) le Dr: No 27.07¢ shot 7 : We. 27 dri// with strength, for the smaller the cut the less work there will be in making it and the faster will be the job. To prevent the tool from binding on small cir- cles, its outside edze is beveled to the back. The round 3%” long, and the shaft for the knob is 142” long. Both are ais Ake central shaft is clamped under %” pieces at each end of the main bar. The holes for these round shafts are bored with a 4” drill. The two pieces of bar are clamped to- gether, with a piece of card- board between. Then, when the shafts are inserted, after the removal of the cardboard, oO FIG.! CIRCLE CUTTER DETAILS It was first put together an eight-inch by three- for a sync rectifier as no ilable for the job. Later, it cut the circular commutator d slip rings from three thirty- sheet brass. quires, in the way of raw ma- ot of %” square brass, or iron round brass, or iron square lathe cutting-off tool zen 6-32 machine screws. The may be the hardest item to cut , dise es of 4” igh it only costs around a dime. approximately three-inch, bar tool steel, used for making lathe hardware store should have it j Place, Cincinnati, Ohio. water into which the tool may be y will speed up the grinding process generated in the tool to be Ed. neat Tech. they may be clamped down tightly. The 4%” central shaft was used because fairly heavy work was contemplated for the tool. Of course, a 4” hole must first be bored in the panel before the circle cutter can be used. If the cutter is to be used for light work, and the 4” hole is ob- Cutting Edge _ FIG. 2 THE CUTTING TOOL BOTTOM jectionable, the central-shaft size may be cut down. The handle used was a glass knob from a drawer pull the likeliest thing at hand. In cutting, the point of the tool should always ride behind the center line of the two shafts. If a smooth edge to the circle is desired on both sides of the panel, the cut

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NOVEMBER, 1928 should be taken through about halfway from the one side, and then finished from the other. The work bench, or a box, should be bored for the central shaft of the cutter. The panel should lie perfectly flat on the bench or box. A strip of wood or iron, bored and fitted below the bench and over the lower locknut on the central shaft, can be used handily as a lever to put a slight formica Base -_ Contact Screw and sounder arm connected — Hard Rubber Extension Copper Plate hoot : [Contact Screw Back Contact 7 - 2) Contact Post ilieseasindies L FIG.3 KEYING RELAY pressure on the cutting point. Of course some elbow grease is necessary to operate the tool, but even an eight-inch circle can be taken through a panel in a surprisingly short time. KEYING RELAY Although making a keying relay from a telegraph sounder is no new job, perhaps a little variety will make another description of such, excusable. The parts of the sound- er were removed from the original iron base and remounted, for insulation’s sake, on an identically drilled piece of 4” formica. The hard rubber extension on the sounder arm and the contact posts were added as in Fig. 3. The contact screw in the hard rub- ber extension was connected to the sounder arm, and the two were used as the blade of a single pole, double-throw switch. The contact post and the back contact were used as the points of the switch. The connections for keying in the plate circuit of the trans- mitter were made as in the diagram Fig 4. The resistance load was used to keep a cur- rent drain on the transmitter plate supply at all times, so that the voltage would not flicker with keying. The regulation of the supply, like that of most transmitter sup- plies, was very poor, around 30%. The approximate value of the resistance load was caleulated from OST Ohms Plate Amps and this value in wire-wound resistors used. A bit of experimenting should give a water rheostat, or a lamp bank, that would fulfill + Resistance pw Load Plate Supp/ - To Transmitter Sounder Arm Back Contact J and Screw _s- Contact Post } = F x ey i= FIG. 4 the purpose. The brass contacts of the re- lay burned away at a rate of about an eigth of an inch a month, so 3/16” tungsten con- tacts were obtained* and fitted to the relay. After breaking .4 of an amp at 1000 volts for some four months, the tungsten sur- faces were still as good as new. If the arc tends to hold after the contacts have opened, condensers should be shunted across the breaks. If possible, the relay should be placed in the negative, or grounded, plate lead. When the sounder arm is connected to the plate circuit, as above, the iron arma- ture on the sounder arm should be kept as far away from the magnets as possible. If the contact screw is used alone, without the resistance load scheme, the hard rubber ex- tension is ample insulation. AMMETERS With the half-ampere, radio-frequency ammeters prevalent nowadays for measur- ing antenna currents, the amateur is some- times hard put to measure larger radio- frequency currents—for instance, the cur- rent in the oscillating circuit of the trans- mitter, or in the tank circuit of the crystal- oscillator, power amplifier. A shunt of No. 12 tinned bus placed across the terminals of a half-amp Jewell thermo couple meter cut the deflection approximately in half. As this was not enough in some cases, a clip was arranged as in the diagram of Fig. 5. By sliding the clip to the left, the length of the shunt was decreased, while, correspond- ingly, more wire was added in the meter circuit, so that no matter how large the current flowing in the circuit, the deflection on the meter could be brought to any de- sired value. No attempt was made at cali- bration of the meter and shunt, for various clip positions, for only relative readings from The Cincinnati, obtained Street contacts may be East Pear! 2. Tungsten Kodel Radio Corp., 507 Ohio

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OST Such calibration would un- useful, however, if the shunt tensively on the meter—and lip settings were accurately PING CONDENSERS monly noticed fault of many mitters that the wave climbs he first few minutes of trans- mention bona fide wave high frequencies the tube 5 VARIABLE-SHUNTED R.F. AMMETER s the helix have appreciable tuning of the transmitter, and tube capacities, because of er things, causes wave shift- ndensers are placed in series capacity is always less than 002 Mica 1000 TOVIIM) G 6 VARIABLE STOPPING NDENSERS ON TRANSMITTER mallest condenser in the group. ndensers may be placed in the late leads of a transmitter, in- usual .002 mica stopping con- se capacities should be made possible without losing an ap- 1ount of output from the trans- careful jockeying, they may be around 100 wufds. each, de- the wave band in which the used, and a much steadier had. The grid stopping con- ven high-powered sets may be ge condenser. A receiving conden- plate lead will stand up-with 800 ts on the plate, but a transmit- NOVEMBER, 1928 ting condenser is needed with higher plate voltages. For the sake of safety in either latter cases the .022 uufd. mica condenser should be left in the plate lead, so that a direct short would not be had on the plate supply should the variable condenser spark over. Figure 6 gives a schematic trans- mitter diagram using the variable stopping condensers. The beat note from a 150-watt transmitter, using three _ ribbon-filament W.E. tubes, would start inaudible at one side of zero beat, pass through zero, and go out on the other side, when keying the set, with the .002 uufd. condensers in circuit. Re- placing these capacities with approximately 100 uufds. reduced the maximum beat-note shift to 150 or 200 cycles. Wp Strays $s QST with deep regret must report the death at Seattle in middle August of Mr. O. R. Redfern, Supervisor of Radio for the Seventh District. For the last several years a splendid friend of the amateur, his pass- ing must be regretted by all members. With the exception of war-time service as a Lieutenant, U. S. Navy, Mr. Redfern was continuously with the Department of Com- merce since October, 1916. Before becom- ing Supervisor at Seattle he was attached to the Second District office at New York. The new Supervisor at Seattle is Mr. Edwin W. Lovejoy, well known on _ the Coast from his long service as a Radio Inspector in the western offices of the Radio Division. In extending A.R.R.L. congratu- lations on his promotion we must also ex- press our pleasure that the new Supervisor is one who knows and understands us as well as Mr. Lovejoy does. The paper entitled “Receiver Character- istics and Their Measurements” that ap- peared on page 23 of the October issue was originally delivered before the Atlantic Division A.R.R.L. Convention held at State College, Pa., on June 15, 1928. We are in- debted to that Convention committee for this most excellent paper and our thanks are tendered herewith. Radio Tube Company, takes exception to the omission of his rectifier tubes from Ross Hull’s mention, on page 28 of the September issue, of a “truly practical” rectifier for 1929 use with high-power tubes. Hull did not mean that a mercury are was the only rectifier capable of operating a high-power tube, but that for various reasons he be- lieves it most practical. Of course, Hull is a purist in matters radio, and other indi- vidual preferences and conditions may dic- tate the use of some other rectifier such as Rectobulbs, Kenotrons or chemical.

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NOVEMBER, 1928 OST 160-Meter Low-Power Transmitter By George B. Hart HEN the average broadcast ama teur becomes interested in two- way communication, he looks with disfavor upon the 1,750-ke. band, because of the fact that he usually thinks that it necessary to use high power and expensive apparatus if effective results are to be obtained. While he is pondering over a catalogue of expensive transmitting goods, or, as is more likely, building a low power set for use on the already over-crowded high frequencies, he little dreams that a low power, yet efficient, c. w. set may be con- structed from receiving parts. Two 201-A tubes are used as the oscillators in this simple full-wave self-rectify- ing Hartley transmitter. The 110- volt a.c. line is used to supply the plate and filament through suit- able transformers. The entire out- fit cost me $10.06. Such a transmitter should es- pecially appeal to men interested in the 1750-ke. (160-meter) code practice and rag chewing, which has recently been inaugurated. It has been used here for several months and in addition to working several locals, stations located fai 300 miles away have been communicated with. Reports ranged from R4 to R9. The circuit of the transmitter is shown in Figure 1. The antenna and oscillatory circuits are tuned by 500-uufd. variable condensers, which in my case were obtained at the local “five and ten.” All key- ing is done in the primary of the plate supply transformer. The 25- watt lamp in series with the powe1 transformer is used to indicate resonance. When the antenna in resonance with the primary the lamp will burn at about medium brilliancy. Coils Ll L2 are wound in the same direction on a 3-inch cardboard tube with No. 18 d.c.c. wire. The coils are spaced % inch. Wind the coils as tightly as possible. 1S as as 1S and Ohio will probably be about approximately the lead-in and portion.—Tech *SDK, 3267 Nash Ave l The most convenient t grounded one which should be 120 feet in length This includes well as the horizontal . Cincinnati, antenna ground lead Editor. 2. It is to get the polarity of on the secondaries reversed if the markings are not observe or if by chance one of the windings is reversed. This be checked by listening to the transmitter with » receiver. When the windings are properly poled will be smoother than when one winding i reversed Tech. Fd as possible of > note a] t SELF-RECTIFIED Pr of 25 turns tapped at the 12th filament return L2 also 25 turns, but tapped every 5 Ll turn wound turns. The possible. bar such as outfit entire panel and consists the with is for short as usual bus The 7x12 leads should be made as The wire may be the is used in receiving sets. may be mounted on a 10x12 baseboard, or may be mounted in breadboard style without a panel. If a panel is used, the outfit may be place d in a cabinet. frequency choke consists of 350 wire on a 2-inch card- The radio turns of No. 30 d.c.c. rr +4} , | ™ DIAGRAM OF THE FULL-WAVE TRANSMITTER EMPLOYING A PAIR OF i-A TUBES ble rece na condense THE CIRCUIT aria ced rece y condense ing condense ed resistor as used ng tube. es tong ona board tube. The plate power is supplied by two similar 6-1 audio frequency trans- formers (mine are of the dollar variety) with their primaries in parallel and their secondaries in series. The filament supply comes from an 8-volt bell-ringing transformer (dollar variety) which delivers 7.6 volts a.c. to the tubes. Those desiring a lower voltage may place a resistance in series with the secondary winding. If old tubes are being used, this extra voltage may help to obtain enough emission. When the outfit will be a simple matter to tune it. Paae ) has been completed it Close the (Continued or

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OST NOVEMBER, 1928 i xperimenting With Bypass Condensers By John F. Rider* series of experiments con- our laboratory, some very in- light was thrown upon the detector plate circuit bypass This information is of utmos! the radio fan constructor, rous of obtaining the bes production. ments conducted were divided ups. In the first group, the to determine how effectively ndenser located in the plate detector tube, across the from the plate of the detec- the negative filament circuit, radio frequency componen. ter rectification. In the second jective was to determine the various values of bypassinz the audio frequency signal ‘ter the process of rectification pleted. fan realizes the need for a r in the detector plat> ed as mentioned in the ragraph, across. the first primary circuit. But, ap- ’ one does not agree upon the pacity; values ranging from 006 ufd. being recommended. ascertained in this series of doubt be of interest to the inclined class of radio fans. the fact that the greatest in- ted to the audio frequency experiments pertaining to juency signal bypassing were The bypass capacities un red from .0005 ufd., to .006 ufd. testing was as follows: An of known frequency was vacuum tube to which was audio frequency transformer primary inductance. The by- was connected across the tance, from the plate of the gative filament. The output audio frequency transformer d to a calibrated cathode ray ube; that is, the deflections are calibrated in volts. With on the various audio fre- known values of bypass variance in the output as he oscillograph screen, when lues of bypassing capacity are tive of the bypassing of the through the condenser. 70 Washington St., Brook- The frequencies considered were 3,000, 1,000 and 5,000 cycles. The following figures the various condensers, expressed in the form of a fraction of the original tube output: 3000 cycles 1000 cycles 5000 cycles Percent Percent Percent 0005 ufd 05 05 1.75 vu) “ 3.00 1.00 6.00 vo2 - &.00 11.80 12.40 003 11.00 14.00 16.40 004 14.00 17.00 90.00 005 - 16.00 20.75 26.00 006 19.00 23.50 31.00 The disadvantages accruing through the use of excessively large bypass capacities in the position mentioned are very evident in the table. For example, the .006 ufd. condenser bypasses 31 per cent of the total output of the tube on 5000 cycles; 23.50 per cent on 4000 cycles and 19 per cent on 3000 cycles. The .0005 ufd. condenser on the other hand bypasses only 1.75 per cent on 5000 cycles; 5 per cent on 4000 cycles and .05 per cent on 3000 cycles. The figures shown apply to the specific case mentioned, x lickser here if used 3 Detector i; 3 C IS THE CONDENSER UNDER DISCUSSION but apply approximately to many similar arrangements where a_ good grade of transformer is coupled to the detector cir- cuit, or where a fairly high value of in- ductance is used as the plate load in the detector circuit. Summarizing, we find that as far as audio frequency signals are concerned, the bypassing capacity in the detector plate circuit should never be more than .0005 ufd. or at the highest .002 ufd. A .0005 ufd. is preferable, however. The selection of the bypass condenser does not rest solely upon audio frequency considerations. It is also necessary to de- termine how effectively the bypass con- denser will bypass all radio frequency sig- nals remaining in the circuit after recti- fication. It is essential that the radio fre- quency component in the detector plate circuit remaining after rectification be by- passed to the negative filament, and so kept out of the audio circuits. If a certain value of bypass condenser will bypass the correct amount of radio frequency current in the detector plate circuit, and at the (Continued on Page 58)

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00, ing sed nal cles 1.75 6.00 2.40 6.40 1.00 00 nm the ies ont tal 50 on on ‘nt les es od, NOVEMBER, 1928 Experimenters’ N the past, these columns have been devoted to the use of the members of this Section only. It is believed that there are many, who though they may not have enough time at their disposal to warrant their taking part in the general program, have time for short experiments that result in interesting information of value to the rest of us. In many cases these men feel that the results of small experi- ments are not important enough for sep- arate presentation in the form of short articles nor that their results may be writ- ten in condensed enough form to allow of their use as “strays”. The result is that such information remains unknown to the rest as far as that particular incident is concerned. We, therefore, feel that in justice to all, these columns should _ be opened to all experimenters regardless of whether or not they are definitely engaged in working out the answer to those prob- lems presented to the members of the Section. We are also aware of the tendency on the part of various members to refrain from reporting the results of their experiments, chiefly because they feel that the experi- ment is not complete in that the entire answer to the outlined problem has not been obtained. Unfortunately, very few of us have the equipment and time to com- pletely cover and solve the major problems listed and the result of this reasoning ap- pears in what apparently seems to be lack of interest in the problem. We know that such is not the case and if you are working on a problem and find that although the entire answer may not be at hand that you have uncovered information of interest let us know about it so that it may be reported in QST. In this fashion others who may be working on the same problem will have the benefit of your findings and the time necessary to obtain the answer to the prob- lem as a whole materially shortened. If you have run across some interesting subject that requires further investigation or if you have learned of a new use for some old equipment or if you have found a new kink which will help the other experi- menters along, write in and let us know of it so that others may get some benefit from your work. Information that is not dis- tributed among those to whom it will be of value is certainly not being used effi- ciently. SPECIAL PROBLEM 66 This problem concerns the electrolytic rectifier and has been held in abeyance many months due to various reasons. The Ost Section Report Aluminum Company of America has been kind enough to supply us with a limited number of aluminum electrodes to be used in the construction of electrolytic rectifiers. Due to various reasons some of those who were originally interested in taking part in these experiments are now unable to do so and we can enroll a limited number of addi- tional men in this problem. We are particularly interested in en- rolling men who do a considerable amount of operating so that the rectifier will be I ay oe mo. 1 . 4t ve C, RFC T \ Cc, | & h Bt | Bradley Leak &2/0 or ‘4 bias battery FIG. 1 f.. ¢ Cl curd fc. are of usna lucs ( v5 ufd ( —.005 ufds. R—IJ00-ohm petentiometer Chokes are of the dollar store varicty. used for “RB” ubstitutes About 30 henries and 85 mils. capacity. in operation as many hours per.month as possible. The aluminum for the rectifiers will be supplied through the courtesy of the Aluminum Company of America while the lead electrodes and the chemicals are to be obtained locally. Two types of elec- trolytes will be employed in each rectifier; one half of the jars will use a borax solu- tion and the rest will use a solution of am- monium phosphate. A monthly report cov- ering the action of the rectifier must be made up and submitted so that the perform- ance can be charted. It is absolutely nec- essary that the drain on the rectifier and the voltage being rectified remain substan- tially constant throughout the length of the test as any considerable changes in these values would render the results worthless. If you are in a position to run a satisfactory test upon such a rectifier and have the time to fill out and return to us the report blanks which will be sent you each month we would be pleased to hear from you. In your let- ter give a brief description of the trans- mitter you are using, telling the type of

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4 4 ed "¢ OST NOVEMBER, 1928 the plate voltage and plate ther with an estimate of the I o} ter } +h l } 1umber of hours the trans- veration each week. A plate s essential in order that one e amount of current being s not necessary that a plate available although this is ve used chemical rectifiers in the brief outline of their construc- amount of success had with r r u tate the number of jars to be the correct number of elec- supplied. SAPCLAY CHARTS o we distributed a number -Capacity-Wavelength charts pplied by Mr. R. H. Barclay. e after our supply of these ted we received requests for Ve i ( op re under the impression that 1 been completely exhausted recently received about 500 ies which Mr. Barclay ran hose of you who were disap- past will drop us a card, we ed to mail a copy of this chart Ww oO W rd of thanks to Mr. Barclay, Webster, 49 Federal St., Bos- appreciation would not be KEYING ze has supplied the following for keying the amplifier of a He states that with this system WS8BQ who are less than three an work within a few kilo- other without the least sign condenser may be of almost and the chokes will stand quite ation without affecting the re- R. F. CHOKES nderson of W7JF and K7AD attention once more the use radio frequency choke. The nake a rigging so that a ring r brass which is connected to ipply side of the choke may be ng may be run along the choke and ted so that there is no r.f. at ipply end of the choke. Such ir be al Ke ? " ( ; the length of the choke. A used over a wide band of id the position of the ring od and thus returned to the n when the set is being ad- w frequency. REPORTS to let us have reports on soon as you have arrived at some information that is of interest to all. In this way others will obtain some benefit from your work which probably would not be obtained if one waits until the complete answer to the entire problem has_ been arrived at. It is the object of these reports to keep others interested in the same prob- lem in contact with the work that is being done so that the least amount of waste effort will be used. —H. P. W. -e- The Northwestern Division Convention OTEL BERGONIAN actually accom. modated che enthusiastic bunch of hams who gathered there from the Northwestern and Pacific Divisions on August 3lst. After registration was fin- ished the program commenced with an in- formal luncheon. At this, talks were given by prominent amateurs. The afternoon was spent touring the Seattle Times press plant and W7FD, W7TX, W7LZ, W7ACB, W7AEV and W7HO, incidentally taking in a lot of Seattle’s “pine mast” scenery along the way. In the evening a technical meeting was held at the Bergonian. Lieutenants Street and Burleigh of the Naval Reserve, and Louie Huber of A.R.R.L. headquarters gave short talks. Then Dave Sloan took the chalk in hand for the next five hours, ex- plaining antennas, transmitting circuits, feed systems, and—well, was there anything he had not explained by one o’clock the next morning? The undersized Leviathan that John Waskey chartered for the trip on Puget Sound did not sink (it’s a wonder) when the gang trod up the plank Saturday morn- ing. Our first port of call was NPC, the Naval Radio Station at Keyport. Chief tadioman Thomas had the transmitter all shined up for us, and gave out blown 500- watt tubes for souvenirs. The large num- ber of V’s sent from NPC’s high frequency set that morning were occasioned by the enthusiastic group of admirers’ whose proximity: detuned it!! Nobody got sea- sick on the return to Seattle, even though we did collide with a drifting plank. The banquet, of course, was the best of all. Seattle’s two YL’s, Doroles (W70OH) and Louise (W7AEV-AGA), sang some songs for us. With Waskey as toastmaster, the gang heard from ’most everyone. Act- ing Supervisor of Radio, Clark was there, and His Majesty, J. King Cavalsky, repre- sented the Vancouver bunch, who were there in goodly numbers. For the rest of the even- ing (and next morning) the brass was pounded clear flat at local ham stations. —I,. R. Hi.

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1928 0 all, enefit d not iplete been ports prob- being vaste Pe ‘COIs. h of . the on fin- 1 in- riven the iF D, THO, ‘pine was reet and rave the ex- uits, hing the [ohn uget rhen orn- the hief all 900- um- ney the 10se sea- ugh | )H) yme ter, ict- Pre, re- ere en- vas ns. H. 1928 NOVEMBER, OST 41 Another Way of Playing an Old Prank By Rufus P. Turner’ T APPEARS that the practice of connec*- ing a microphone in with one of the audio frequency stages of one’s radio receiver, and speaking into that instrument so that the voice issues forth from the loud- speaker, has become almost universal at radio parties. The stunt came into vogue somewhat less than a year ago, subsequent to the appearance of a magazine article which depicted the amusement afforded a group of callers when one amateur incorp- orated an ordinary telephone microphone in the circuit of his receiver, and made his guests believe they were listening to broadcasting from the Antipodes. The microphone had easily been included in the primary of one of the audio fre- quency transformers, having previously been connected with a concealed pair of wires extending from the room, some dis- tance down the hall, in which it was lo- cated. Between selections, one confederate obligingly opened the outdoor antenna switch, in order that the real announcer would not be heard, while the second con- federate announced some Australian sta- tion. The writer recalls a perfect enaction of the prank at a radio party, where both the confederates were equipped with small, portable receivers in order that they might know exactly when the antenna switch was to come open and the fake announcement made. Also, confederate number two, who had charge of the microphone, knew pre- cisely what selection was to follow and made his announccment accordingly. The guests, grouped before the loud- speaker, were amazed, to say the least, upon learning so unceremoniously that their host’s radio receiver could “pick up programs from across the seas.” Not one of them suspected the whole affair to be a practical joke, so nobody consulted a news- paper to see if the program was not being broadcast by one of the local stations. The affair was such a success that the writer determined to “pull off the stunt” at acoming meeting of other radio men at his amateur station. But the fact presented itself that radio men couldn’t be fooled by the microphone prank. They would surely examine the set, discovering the wires con- nected at the other end to the remotely lo- cated microphone. The difficulty was soon overcome when the writer hit upon the idea of connecting the microphone with the receiver, not di- *604 East 5lst St Chicago rectly, but through the medium of induc- tive coupling. The concealed wires con- necting with the distant microphone were made to terminate in a loop of a few turns. (The number of turns and the prop- er diameter, it was found, vary with the type of radio set and both must be de- termined by experiment.) The loop was made of number twenty-two cotton-covered wire, and was carefully placed beneath the cloth cover, upon the table that held the set, in such a way that inductive relation was established between the turns of the coils of the receiver and the turns of the loop. The loop is similar in performance to that employed by transmitting amateurs in the so-called “loop modulation.” It is only necessary to turn on the receiver and, when the loop and one of the coils in the receiv- er are in inductive relation, speak into the microphone. When the coils of the set and the loop are near enough to each other and the wires connecting the loop and micro- phone are not too long, the results are quite pleasing. The writer has met with success both with regenerative and radio frequency broadcast receivers. The prank went over big at the writer’s party, providing no little entertainment. The guests, all radio men, searched the set for telltale wires, without success, and ap- peared quite von mentis when the was subsequently revealed. $pStrays $s The O. W. says she can’t see why they call them short waves unless it’s because there aren’t enough to go around. compos secret Dr. Lawrence J. Dunn, Director of the Hudson Division, announces the dates for the Hudson Division A.R.R.L. meetings of the 1928-29 winter season. The dates fall on the first Monday of each month: October Sth, November 5th, December 3d, January 7th, February 4th, March 4th and April Ist. The meetings are held at the Army Build- ing, 39 Whitehall St., New York City, with room for about 300. Interesting programs, with technical talks and discussions of amateur problems, will be provided. There is no charge whatsoever. Members and The Y. L. thinks that all political speeches should be broadcast on short waves only— the shorter the better.

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OST NOVEMBER, 1928 Some Radio Uses of Lamp Banks By I. Vee Iversen* E are a few uses for a lamp bank. e things are really handy to ve around. I have just completed er oscillator outfit and in it the use of lamp banks a great tart with, I am using W.E. oxide- es, in which the filaments must rm even when not transmitting. - Toggle switch meme | — ‘te woo watt samps com Smwrtl) /25¥ 6o~ po000000 TOTTI T TTT FIG I solves this nicely as shown in I use one 40- and one 100-watt primary of the filament trans- ese take care of the VT-2 and D. For a VT-2 and a UV-203, ary to use one 40-watt and two nps to give the rated voltage 7 6) r + ©) ©) © | wowall = . aA high Voltage hs, ap ¥ ©) > | 5) | 3 | 0) 25 watt } When I give the “ga” to the throwing this toggle cuts the tage in half but keeps the now, the VT-2 will not take the oltage as the 50 watter. Fig- ws my way of getting around a bank of 12 lamps (in series) e plate supply. Eleven of these rated at 10 watts and 1 at 25 e voltage drop across the 25- the negative grid bias on the mplifier. This eliminates the of batteries for this purpose ltage drop across 6 of the 10- th Ave., N. W., Seattle, Wash. watt lamps gives me the voltage for the VT-2 plate. By changing the size of the lamp supply- ing C-bias the value of bias may be changed. With a 25-watt lamp and the VT-2 drawing 40 mills and the 211-D draw- ing 160 mills, the drop across these lamps is about 105 or 110 volts, which makes the set work satisfactorily. To my notion, the use of lamp banks should be increased. Since I have gotten used to using lamp banks a new use suggests itself almost every day. For a fellow using a mercury are for power supply, the above will furnish an admirable keep alive load besides the other uses and at the same time makes a good fuse—on excessive plate currents the C-bias lamp will go west. The C-voltage then goes up, blocks the plate current anJ saves the tube. -e- Standard Frequency Transmis- sions of WWV HE Bureau of Standards announces a T new schedule of radio signals of standard frequencies for use by the public in calibrating frequency standards and transmitting and receiving apparatus. This schedule includes many of the border frequencies between services as set forth in the allocation of the International Radio Convention of Washington which goes into effect January 1, 1929. The signals are transmitted frem the Bureau’s station WWV, Washington, D. C. They can be heard and utilized by stations equipped for continuous wave reception within a radius of 500 or 1,000 miles from the transmitting station. The transmissions are by continuous wave radio telegraphy. The signals have a slight modulation of high pitch which aids in their identification. A complete frequency trans- mission includes a “general call”, and “standard frequency” signal, and “announce- ments”. The “general call” is given at the beginning of the eight-minute period and continues for about two minutes. This in- cludes a statement of the frequency. The “standard frequency signal” is a series of very long dashes with the call letters (WWYV) intervening. This signal continues for about four minutes. The “announce- ments” are on the same frequency as the “standard frequency signal” just transmit- ted and contain a statement of the fre- quency. An announcement of the next fre- (Continued on Page 58)

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NOVEMBER, OST Parslow, 27 Eastbourne Road Junction, London, S.W. 17, England. Alan G. Brown,.8 Mangarra Road, 7, Victoria, Australia. em-smuk ep-lae ep-lae ep-3ap xep-Ilma ( "xe chos lovakia. ej-lfb ei-lfe ei-lmt ei-lmw el-lal em-smuk em-hmzf en-odj en-ofp en-ojm es-2nag et-tpar et-tpkx Stormont Rd.. W. 11, England G2BOQ, H. E. w2vi wack w3ava w3awq w3bm w3cdk w3ahk w3ke w3tr wdaba wdacv wS8acm w8awf w8bijb w&cau wkenz wkdeq wkdtn w9anq w9fci w9mt velbr ve2bg nqg-2kp nq-2jj nz-fr5 sa-az2 sb-2ar sc-lai fo-a3z wnp. A. Comender, Burg, Meinesrlaan, 9/R, Rotterdam, Holland. wl ei wlka wlalb wlapi wlia wlbyv wlcaa wlaeh wliy wlahx wlaia w2uo w2com w2gv w2kl w2cxl w2inb w2avb w2aeu w2bo w2nf w2arb w2atr w2dg w3bav w3ge w3aih w3wj w3cdk w3anh w3auj w4ft wdacx wiagr wdiacv wdiaej wive wé4oh wSex wSaxa w%cia w%9cax ve2br ve2ca vedbt k4agf nq-5fl nj-2pa ag-skwg ag-6grb ag-rbl4 as-l5rw as-l5ra ff-Spj fq-Shpg : sa-de3 sb-lea sb-lbo sb-lid sb-lah sb-lbe sb-lcj -law sb-laf sb-lbs sb-2bg sb-2af sb-2al sb-2aj ab-2ah ab-2ay sb-6qa sc-2ab sg-a7 su-2ak xnu-7eff xnu-7ef xep-lms xef-Sgcr xed-7gb. ag-rb64 fm-tun2 ef-RO91, C. Conte, 24 Allee du Rocher, Clichy-sous Beis, (S. et. O) France wlack wlafb wlafl wlagw wlajx wlaup wlasd wlaxx wlayt wilbbt wlbgq wlicmf wler wlgex wlim wliy wlkb wlie wler wlahz wicnz w2ajb w2alu w2ang w2api y2Zate w2baj w2baz w2bbl w2bek w2brh w2ble w2bm w2bmx w2bsm w2cbk w2cin w2cky w2cuq w2cxl w2dr w2dl w2fa w2gj w2id w2ti wS3aic w3amx w3anh wiapn w3ard gf w3che w3ckl w3ec w3ga w3tr wiaam wdaau wiaay wiabl wdacz wdado wiahy wiaq wica wife w4fi wd4hz wile w4nu wirj with w4vl wi5apo woark wSadg wadu wkSagy wSagq wSaht wk8air wkaso wtawp wkaze wSbaz wkbm wk&box w&8bpl w&brl wkbvge wS&cft w&cfh wScnr wScnz wSchr w&csv wScvj wSdid w&dnf wSduw w&rh wavz w&bjia wkdem wSdpz wdsy wara wSauh wicrd wScya wicue wSenr wSIewh w9fqs w9mn w9bac nem velbr nq-2yt nq-2xc. ec-RP 19, Alois Weirauch, Mestec Kralove 9, Czechoslovakia. wlbux wlnp wirf w2apv w2ass w2bjg w2bm w3anh b w3apx w3bms w4dt wkaau wSbox wkduw wiabvy w%crd nj-2pa nn-7nic np-4ug nt-2fp nq-5fl nq-7ex nx-lab nz-fr5 fq-pm fq-8hpg fa-8rya oa-3vp i-de3 sb-lah sb-lai sb-lbs sb-lea sb-lcg sb-lcj sb-lid b-2ar sb-2ay sb-5af se-3cj sg-a7 su-led su-2ak sb-lbm (20 meters) wlarq wlawe wlbyv wiemf wlfs wlsz w2adm “ pi w2azo w2cx!l w2vi w3adm w3edk wkaxa ne-lap ne Zea ne-Sae ne-Swge fq-Shpg oa-5gh sb-law wnp Woa ed-7XX, H. Glistrup, Copenhagen, Denmark. wlage wlaqt wlbux wlby wlbyv wlemf wlfs wiry wixm w22agn w2api w2arb w2avb w2avz w2becc ’hbfa w2emu w2kx w2lx w2nm wdact w9adn woIbay ve2be ve2by ve-2ca sa-2az sb-lat se-law sc-2aj tie sc-llt su-Ina fg-ocya (Continued on Tl’cae )

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™ > | ee er NOVEMBER, 1928 aS yr 4/ PS : x Conducted by A. L. Budlong been a gratifying re- to the request that National appoint official I.A.R.U. ndents, and see to it that on amateur activity are department for publication. ulative lags of distance and -half-in-advance publication several months before sev- es become regularly repre- the point is that they will make this a department h, you can be sure of find- vices on changes in legis- ions in other countries of plans and policies of the nal amateur organizations, ppenings. The codperation ection is necessary in lish this. Please do your AMM VISITS ADQI EK4ACI ARTERS pleasure, on September to A.R.R.L. Headquarters, member of the Executive the D.A.S.D., the German a prominent amateur, and nd owner of ek4CL. Dr. country for six months to research work at Cornell hopes at the same time to acquainted with Amer- thods. Hartford is greatly appre- Doctor has to report to Cor- October, and Hartford is Cornell. . e looked over the Head- alked about the ILA.R.U., 1any points which had been tor’s mind regarding the n Germany. linner was held at a local we had Dr. Lamm, Mr. ter, W6HM, Marshall ton, and the Headquarters It was a most in- formal and pleasant evening, and will be remembered by all of us for some time to come. After the dinner there were short speeches by Mr. Maxim and Col. Foster, and a most gracious one by Dr. Lamm. Following this, the affair turned into a thoroughly delightful hamfest. About 10:30 P.M. everyone adjourned to the main dining room of the hotel for coffee an: sandwiches, and the hamfest was resumed, to be continued until the management closed up the place at midnight. We hope Dr. Lamm has a pleasant stay in this country, that he will have time to attend some conventions, and that he will make many NU QSOs. This last fact seems assured, since the Doctor has expressed the intention of taking out an operator’s li- cense and getting on the air as soon as pos- sible. For the benefit of American hams, we might say that Dr. Lamm speaks excel- lent English, that he can receive up to thirty words a minute, and that his sending (as we heard it at 2ALU’s the night ek4CL landed) sounds like machine sending at twenty-five words a minute—with a straight key, too! FRANCE In a recent issue we chronicled the fact that an election had been held in the Reseau Emetteurs Francais, and listed the name of the new president. Mr. Robert Audureau has now supplied us with the names of all the new officers, which are as follows: President: J. Reyt, 8FD. Vice-Presidents: R. Desgrouas, 8LH; J. Bastide, 8JD. Secretaries: tin, 8DI. Treasurer: R. Larcher, Honorary Presidents: Pierre Louis, 8BF. President-Founder: Jack Lefebvre, 8GL. Mr. Audureau also advises us that the only address to which communications fo the R.E.F. should be addressed is: Larcher, B. P. 11, Boulogne-Billancourt, Seine, France. R. Audureau, 8CA; R. Mar- RO1O. Leon Deloy, 8AB;

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NOVEMBER, 1928 We offer our sincere congratulations to the new officers of the French section. The R.E.F. now has more than 800 members, indicating a steady and healthy growth. This is splendid. GREAT BRITAIN Great Britain is one of the countries maintaining an official correspondent for this department, and it is a source of much gratification to receive a report each month. The latest one follows: “What with holidays, dud conditions and fine weather resulting in QRM from cricket and tennis, there does not seem to have been very much DX done during Au- gust. Certainly conditions were OST 45 ulate him most heartily on this appointment, but at the same time we regret very much that his good fortune deprives us of such a satisfactory correspondent. We hope that the R.T.U. will immediately appoint some one to take up the work which Mr. Megaw must now leave to other hands. The report follows, and contains a most interesting re- sume of amateur progress in Northern Ire- land: “As this is the last time these notes will be penned by the present writer, perhaps a few words in retrospect will not be out of place. “It is now something over three years since the first amateur transmitting licenses pretty bad; as 2XV put it, fancy wanting a DX report when first district Yanks, even, are rare as roses in January! 2XV, how- ever, is running a schedule with oa7CH on 23 meters. 2NH, too, worked OA every morning for a month on that band. 2CX keeps a sked with oa5HG and also raised several NUs, including a nine. “5BZ raised the first, second, third and eighth districts, NC, OZ, OA and SB and needs only to get an Asian station for his WAC, wherefore he finds life good. 5BY says ND, with only about three dozen Yanks, SB and SA. If that’s ND, OM, let’s have a real report, Hi! 5YK worked RESEAL GEORGE AMATEUR STATION ebAFT, OWNED AND OPERATED BY NEELEMANS, TRAFFIC MANAGER OF THE BELGA AT RBRUSSELS, BELGIUM, is one of the nest w dely known amateur stations in the world. The circuits SU on 23, but is very busy with sa Mesny, with two 150-watt Mullard valves. An Esco motor ten-meter work. 6SM_ hooked fk4MS. 2AX moans about con- dla ditions, but worked two or three. ie: eh 5ML worked the U.S., but not ts cwner much else. 6CI exercised his Morse on the long-wave commercials. FB OM! Hi! 6BY worked some NU’s SB and SC, “6BB worked sc3AC with 4 watts on 25 and NU 6, NC 5 and OA with 8 watts. Good work, OM, and more like the old 20-meter stuff. 5LS ran a nightly sked with NU while unlII was at his shack. 5BQ found things good on 45 and worked several nines. 5YU had a stab on that band, too. Long waves these days, OM’s! Several hams have had the pleasure of meeting nullIl, both at their shacks and also at the keys of some of those he visited. nu6BJH also called on 5BZ and S5BY, to their great pleasure.” NORTHERN IRELAND With this report, the series of interesting articles contributed to this department by Mr. Megaw will come to a close. Mr. Me- gaw is leaving Ireland to conduct research work in London for two years. We congrat- generator supplies 1100 volts for them. The antenna is a half- pelin working on 32 meters. 1/1 instruments are and the receiver is a Grebe CR-18 These, with the and the Vibroplex key cb4FT, to use the words of “rather a Yank station in appearance”! were issued in Ireland. At that time, there came into being a few isolated transmitters, all using very low power and operating under somewhat irksome restrictions, and this represented the result of several years of effort on the part of some of those ama- teurs. (It will be remembered that the un- settled political state of the country was the cause of this prolonged delay.) “After about a year, the numbers had in- creased sufficiently to warrant the forma- tion, in September, 1926, of the Radio Trans- mitters’ Union (Northern Ireland), an or- ganization which is run on rather unusual lines and which has been a great success and a considerable factor in the development of amateur radio in this province during the last two years. It now enjoys the recogni- tion of the Post Office and broadcasting authorities. Its membership includes al- most all the transmitting amateurs in Northern Ireland and membership of the (Continued on page 54)

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oOSsT NOVEMBER, 1928 Correspondence The Publishers of QST assume no responsibility for statements made herein by correspondents. Our New Calls Undelivered Messages Box 698, Uxbridge, Mass Pampa, Texas Editor, QST: reer ’ On September 14 and 15 the Blackstone 0 , , re r ps > * de y r . . . .. a teal tte oe Valley Radio Association held a booth at W_5NW. the Uxbridge Fair and accepted messages derstand this new call business wg the patrons of the r+ At the end they should be printed in this we had 138 messages both 1COS at his sta- W5NW. In other words, all U.S.A. tion in Milford and 1BZJ operating the its te teltee Ut tenteel of & Assn’s station 1JB were at the key for two theretofore. And the W is as days getting off the messages of the hook, t of the cohen tie needlens “= stations they QSO reported them R7 the isthers, and sheeld be given good note very steady but when asked to ? take traffic all they say was, “lot QRM or rominence he QSL card. In . ne % aa pond es — = be es QRN gid to QSO u OM, 73,” and they would ime they send thelr call. A cali ©&© for somebody else without waiting for coe ges ie : : . ns any reply from our stations. According nade > , ray: . A ide _in the following way: CQ +5 ‘the reports made by some patrons only W5NW W5NW W5NW. _ about 50% of the messages that were sent Wayland M. Grove, W5NW from our station were ever delivered to the ee a addressee. I think that this is a very low ne have ealls beginning with W or Mark, and that it gives our organization a | KWE, so do amateur calls now bad name from those whose messages were e letters, like W5NW and K6CFQ. not delivered. The officers of the associa- GONM. GieMU ee ae tion wish to thank those who did take traffic r letters are part of the call, not to from 1COS, 1BZJ and 1JB and relayed or d to be printed in caps. See our delivered it. 1IAJK of Worcester deserves ‘on this subiect. "We recommend: the credit for the way he stood by for those vormediate” until such time as gov- tWO days giving us all help in getting the their amateur calls, and that in traffic off in his direction. I hope that next ci uch, calls we, ise lower-cnss year when we have a booth we will be able Lemtaion @tite thane tethers. to hit the 100% mark, and we can do it with the codperation of the gang. Again I wish to take my hat off to the few but “royal The Extra First Grade hams” who did coéperate with us this time. 2631 Garfield St. N. W —Wal'lter H. Kozaczko, See’y, Blackstone ae sarhiel< st. —_ *? Valley Radio Association Washington, D. C. : rial on the amateur extra first in the September issue, was great ioieanat by myself, and, I The Splatter System? other “hams”. I feel, as you ; ere hat we never really appreciated ea a Syracuse, N. Y. license until it was taken Editor, QST: Are we to gather from E. O. Hurlburt’s erest you to know that, having letter in September QST, that an ideal 10- litorial, I decided to take time meter beam transmitter can be had by ar- k, and accordingly, was issued ranging a sea water tank atop the house amateur extra first class license and allowing the water to spray down be- the new series. Now that the hind our 10-meter vertical antenna? started rolling, here’s hoping Would you suggest a pyrex pump to re- eurs will take out this. license. turn the water to the tank? _Willard R. Burton, 3NR —Alfred R. Marcy, Chief Engineer, WFBL

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1928 Mass. stone th at sages > end | Sta- the * two hook, n R7 id to M or rould + for ding only sent » the low on a were oC ia- -affic d or rves hose the next able with vish oyal ime. fone tion rts 10- ar- use be- re- BL [EXTRA] THE @& NEWS [ExrRa] VOL. I NOVEMBER, 1928 NO. 4 Showing New Receiving-Xmitting Coils for 1929 More About Frequency Meters AA NY AU Frequency Precision Obtained With This Meter The findings of the A.R.R.L. Technical Dee The New Plug-in Coil velopment Staff are to the effect that a cer- tain, single capacity cannot be shunted by Efficient operation is assured by the us2 various coils, and give complete coverage of of these plug-in coils wound on one piece each amateur band. The new REL Frequency _ bakelite forms. Threaded ribs allow ac- Meters provide a separate coil and condenser curate space winding. Construction em- for each band. Each meter is accurately bodying three windings on one form per- calibrated to 1/10 of 1% of the measured fre- mit quick changing. Special Spring con- tacts to take the coil plugs. Employing heavy copper enamelled wire they are These frequency meters utilize one of the most suitable for high frequency receivers accurate resonance indicating systems known. and 210 type low power transmitters. Extremely sensitive and permitting of very A ; ? loose coupling between transmitter and meter. 1 he coils = used with the new — These meters should be the mest important pe leapt pape aga AB on piece of equipment in every “ham” station. that will set new standards for Short Wave performance. quency by means of a crystal standard. Precision equipment will be an absolute neces- _ for all stations that are operating after The plain bakelite forms may be ob- January 1, 1929, because of the narrowed aimed rind your m coils or they bands and because of the drastic consequences ae to — am — coils on t ey if a station operates “off wave.” rll ne anes onee a ,and wound for transmitting and receiving work. They are also used in combinations of three or four to make kits for the pop- ular circuits. The REL Precision Frequency meters FILL THE BILL Free and useful information on How to Build and Use New 1929 Receivers and Transmitters is yours for the asking. Five modern high frequency receivers, including the well-known Standard Regenerative receiver, the circuit employed in the Screen Grid Tube and a Special Super-Hetrodyne is described. 100 Wilbur Ave., Long Island City Radio Engineering Laboratories, Say You Saw It In QS T It Identifies You and Heips Q S T 47

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48 PATRONIZE THESE CH | | i RED DISTRIBUTORS CENTRAL NITED STATES URS 8th AND oth DISTRICTS o Rapio APPARATUS Co. sO. DEARBORN STREET, CHICAGO, ILL. Radio 1921 ition Understands is comprised ‘Hams” Amateur Catalog REL) | Equipment Since because it old-time New Our —\ BRAZIL -f SOUTH AMERICA M BARROS @& CIA OB. RUA S. JOSE 70 SOB. POSTAL BOX 89 RIO DE JANEIRO Address, Radioparte, Rio de Janeiro Avenida S. Joao 4, S. Paulo, Brasil Your Specifications neers are Experts on Wave Equipment ON THE PACIFIC COAST RED RADIO SUPPLY CO. SO. BROADWAY, ANGELES, CALIFORNIA REL) y Standard REL Data Forwarded ED WEST JOHNSON CO. WASECA, MINN. Headquarters for Our New Write Ready R APPARATUS Say You Saw It In QS 1 Beginners 6 Airlie Street, Worcester, Mass. Editor, QST: Here is something that has been on my chest for some time, yes years in fact. Mr. Brown’s letter in the July QST prompts me to unload it. First and foremost, get me right. I certainly agree with Mr. Brown that we should all have patience with the new hams and give them a slow and good QSO when they call us or when we answer their call. If they ask us to QTA or QRS, do so and be a good scout and not a snob. We were all beginners and well do I remember my own feeble attempts some years ago to get the other fellow’s drift. Now for the load! A number of times, I have had the following happen and only recently was it brought back to me with force. I worked a chap who asked me to send slowly as he was a beginner. .I, at once, changed to ten per with QSZ. He gave me a report good enough for any conditions of the air but asked me to send slower. I cut the speed to about six per with QSZ and still he was unable to get what I said. About this time, I realized I was in for a long session and rather than cut it short, repeated the dope all over again and still nd. Now, what would you old timers do in my case when he came back and said he was sorry but would I please send slower? This time I went down to nearly zero per and got “rr ok”. Well, that was better, but I saw that there were no signs of my getting away so I recon- ciled myself to my fate. Now, fellows, it became necessary about this time to call it off so I did but was out of luck as he did not get me. Wasn’t I justified in giving him my 73? Well, I am perfectly willing to spend some time wit hanyone but if he is not able to copy ten per or anywhere near it, he has obtained his license in some incorrect manner and whoever signed his papers is responsible for his being on the air before his time. If a fellow can’t copy the required speed, he must expect a little rough treatment. No one should be on the air who can’t copy ten per with signal streneth and atmospherics considered. —Clarence J. Green, 1ASU-1BCO. (Continued on Page 78) Identifies You and Helps Q S$ T EF A An pal ane tal for th me col wh sol an on. spi del gr

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nd er ‘et ed an er pu ck se to ig nd ot it, ne is he ny le he al 0. fexTRa] THE €£) NEWS EXTRA VOL. 1 NOVEMBER, 1928 NO. 2 NEW CONDENSERS SHOWN FOR FIRST TIME-~ EXPERTS SAY “SENSATION OF YEAR!” Multi Type 187 EFFICIENCY AND DX ABILITY NEVER EQUALLED Announcements of radical new ap- paratus are not daily occurrences at REL. So when they come, you sit up and look alive; for experience has taught you that REL is pioneering for the good of amateur radio; that they are developing equipment to meet the needs of changed operating conditions. These condensers are what you’ve been waiting for. They solve the riddle of the narrow bands and afford satisfaction heretofore only hoped for. Nothing has been spared in order to make these con- densers THE BEST. The results are gratifying; and after all, only results can substantiate our storv. —_ 17 ICW NEW! NEW! NEW! 1929 Receivers and Transmitters How to Build and Use Them A booklet which describes the construction and operation of five modern high frequency receivers is now ready. Included among these are the well-known Standard Regenerative receiver, a circuit employing the Screen Grid tube, a special Super-Heterodyne, etc, A companion book on 1929 transmitters and circuits will be ready next month. Before contemplating recon- struction, secure this new REL data. It’s Free CONSTRUCTION EXPLAINED FACTS SPEAK FOR SELVES The new Variable Receiving Condensers are shown here for the first time. These condensers will be an abso'ute necessity in 1929, when the wave bands are narrowed causing great congestion. Using either of the new condensers will allow the operator to spread each waveband over the entire tuning scale of his receiver. Several outstanding features are; die-cast aluminum end supports, giving extreme ruggedness. Large single conical bearing, which prevents end play or side thrust. Insulated stand-off bushings, enable these condensers to be mounted on metal panels. The rotor tension is maintained by a large three finger bronze spring, assuring positive, even action during the complete rotation of the rotor A patented rotor plate contact assures ab- solutely noiseless action. The rotor shaft revolves in a pool of mercury, making a perfect constant con- tact. Both the Stator and Rotor plates are of ex- tra hard, heavy sheet brass and the shaft is standard L.” allowing the use of any dial. REL ¢ I e No. 181 is a two plate variable condenser, ral { that the stater plate may be moved permitting ed \imum ipacity to be obtained This condenser lapts itself » frequency meters and high frequency receivers i is advise y Mr Hull of the American Radio Relay League mn page 14 of the October QST. REL Catalogue No, 187 is a combination semi-fixed tank and ntinuously variable vernier condenser This model is so ar nged that 1 perfectly larg semi-variable iir-spa ed con lenser is shunted by a continuously. variable two plate con lense The tank portion of this condenser may be set at a ertain desired capacity and the variable element can be used to cover only the exact frequency band desired A special feature of this condenser is that a pre-determined setting of the tank circuit may be indicated on a disk on the tank , roto shaft enabling constant re-setting to any desired ca pacity This condenser may be advantageously used in a low power transmitter where a “‘High C"’’ cireuit is desired as on page 26 of September QST exceptionally adaptable for re- eeivers where a stated ‘“‘lump capacity is needed for each il so that the continuously variable vernier will spread each band over its entire tuning scale The ideal condenser for Westman'’s Traffic Tuner (Septem- er QST RADIO ENGINEERING LABORATORIES, 100 WilburAve., Long Island City, N.Y. Say You Saw It In QS T It Identifies You and Helps Q S T 49

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REL) Ra)

\TRONIZE THESE @EL) DISTRIBUTORS

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Greater RED New York Area H. McMANN 2 WARREN ST., N. Y. C. Stock of REL Apparatus Always on Hand Sales Organization is Give Prompt Service Write Us

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Say You Saw It In QST It Identifies You and Helps Q S T —MeStrays's For those who are using remote control relays for the making and breaking of the power supply circuit to the transmitter and are objecting to the amount of juice used by the relay it is suggested by oh6DB that a solenoid type of relay be used, He finds that a solenoid and plunger arrange- ment in conjunction with chain-pull socket works very well. A fuse can be screwed into the socket to complete and protect the circuit. The relay can be operated with a single impulse rather than a continuous current which must flow all the while the circuit is to remain closed.

Calls Heard (Continued from Page 42) KUTM, Steamer John P. Reiss, Clyde C. Richelieu, Operator i (40 meters) wlave wlaep wlbkf wilbfz wleq wlbux wlxi wlxk wlxv wienf w2al w2aue w2agn w2ahh w2ahi w2aim w2alu w2bmm w2com w2adm w2aoct w2baa w2bm w2ctp w2ctq w2dg w2nf w2wd w2be w2bkz w2avp w2cea w2xaf w3ard w3anu w3aua w3oh w3tq w3dqv w4js w4mx w4nu w4rq wdiut wdiaar w4hk w5aad whiaug wh5afe w5afx w5ark w5bj w5bjie wigf wie wi5mf w5imx w5ql w5uo wive w6eze w6xb wilz wi7id wSahe wSalu wS8bei wSbeu wSbky w8blb wkbm w&bme w&8bts wScau wScnt wSeze wScx w&dde w&dcm wSeew wkdde wkdgb wScft wS8cnz wS8ejo wkbry w&dvl wShx w8jj w8li w8wo wS8iu w9ack w¥acu wake wSaqe w9bbl w9bga wSbhz w9bnf w9bpyq wIbwa wcej wScjh wicph w%9arf w9arm w%axo w9axu w9aug wSben wScn w8aug w9bab w9bam wIcek w9dap w9doj w9dwk wSdzw w%9csd wcyb wSden wSdim w9drj wSdwd w%efe wSecs wienb wiezd wSecd wSergp wIeho wieji wIelb w9enn wieae wexc wSeyh wSeqk wSdyw w%bpl w9ben widfj wiayu wSbkz wcjs WS8dbk wdzl w9brp wbtq weer wS9dwm wSdb wSayx wofdr w9fyeg wfac w9fdy w9flb wofis w9fjid wSfkz wSfuy w9fsn wepe w9fqs wofle wSkv wSlf wkd wSjmi w9Imi wImg w9my wre wll wSod oa-2ra oa-2ns oa-3kr oa-2yi oa-5mb oa-3vp oz-4am sc-2ab su-2ak velbr velcb k7to kdaaw. (80 meters) wibld wilecra wicos wlga w3age wiafw wkaaf wSarb wSarx wkbbr w&Scno wSddm wS8dsf w&li w*dpi w9bxr wSbwz wScvi wSczf wSdid wSdek widgw wSdec wSekw w9eru wSfaw wSfdw wIefu wIge wad. (20 meters) wlanh wlalb wiblu wiblv wicez wickb wicio wlda wldf wlkq wljr w2azo w2bdj w2bac w3ath w3aqm w3cx w3bph w4gd w4ve wiaaq w5amn w5baz w5bbe w6ano wé6csj w6cuh w6bpm wé6dwi wédwp w6no wisi w9afx w9aqz wavy w9baz wIneb wbkz wIccp wIcub wSefe wSfyp wus ne-dio se-lah nj-2¢4 giby gé6ut. W7MF, Harold D. De Voe, R.F.D. 2, Medford, Oregon aclpp aj2by aj2dk ajd4dak ajd4dk ajdzz aj7mf jxix efSorm fllab foa3e foa3z foade foado fq&Shpg kito nj2pa nmlg nm9a nninic nn7nic nncab nagdfl nani nq5ry napwv nt2fp nxixl nzfr5 oa2ac oa2cg oa2hm oa2kj oa2lj oa2ns oa2rx oa2yj oa3ax oa3cp oadhe oa3kr oa8vp oa3wx oa3xo oadab oadbb oad4rj oa5icm oaShg oaSja oaiwr oaich oalcw oaT7dz oa7jk odljr od4as k6ch k6clj k6ekx oobam oplad oplem oplhm oplhr oplpb oplpl oplre op9pl ozlar oz2ab oz2ae oz2bi oz2bz oz2gp oz3ai oz3av oz4am sblaw sb2ay sc2ab selem se2ea spcbl ve3bm veddi veddg ved4dj WIBUX, DH. Borden, Touisset, Massachusetts (20 meters) ea-jh eb-4dau eb-4bn eb-4rs ed-7bb ed-7hp ed-77g ee-ar9l ef-lm ef-Saxg ef-8bf ef-8btr ef-Xcs ef-Xct

| =< ~ ej -—— | Ir ti

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trol the tter uice \DB He ige- *ket wed the ha ous the iaf lpi rw id. ‘io th vp kz ea ix to ni « Ir ie y EXTRA THE @EDNEWS EXTRA — Vol. I. NOVEMBER, 1928 No. 5 10,000 Inductances Now in Use. New Transmitting Condensers Going Fast = ~ > a pa \SAaaad Now Famous REL Transmitting Inductances. Peerless For Years- REL inductances need no introduc- tion to the thousands of Amateurs who have been using them for years. Here is one piece of apparatus that has won the acclaim of all who know that a transmitter needs inductances. Flatwise wound copper nickel plated wire mounted on crystal glass spacers, they should be used in all circuits using 1-1000 Watts. There are two types, “L” for 40, 80 and 150 meters wave lengths and “S” for 20 meters and less. Single and Double Units are obtainable in either type. Single Unit includes three clips and the Double Unit has six clips and two glass coupling rods. If you have not yet used these in- ductances, don’t wait any longer. Join the ever increasing ranks of those who use the best—REL Products. : 4 4 ; 4 - eS Oar ear era reuserecommem # Pa’: The Transmitting Condenser That Has Caused a Sensation in Short Wave Field. Introduced as a Super Condenser for the Super-Set, it won immediate attention and popularity. It is used in all the famous REL higher powered trans- mitting kits and is in increasing demand by set builders. It is a job that is built to stand the gaff. It will prove its true worth under severest service conditions. To say that the construction is Sturdy is but to scratch the surface. Heavy brass plates—cast aluminum end plates —husky steel rotor shaft—conical ad- justable bearings. Best possible insula- tion assured by the use of heavy isolan- tite blocks—accurate spacing and Over all strength carried to an access. That is an outline sketch of one of the finest Condensers designed for Short Wave Transmission. Specifications on _ re- quest. They may now be found in Lead- ing Amateur Stations, U. S. Army and Navy, Commercial Stations ard _ by others who know the best. WRITE TODAY FOR YOUR DATA ON 1929 NARROW BAND RULES Radio Engineering Laboratories, 100 Wilbur Avenue, Long Island City, New York Say You Saw It In QS T It Identifies You and Helps QS T 51

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The Choi Million Tireless Sentinels a | RADIO Z TUBES are ever alert. They respond to every radio wave and give you clear, natural tone reproduc- tion. Ask for them by name Cr. CUNNINGHAM, Inc. ork Chicago San Francisco red and sold under rights, ventions owned and/or Radio Corporation of America Say You Saw It ef-Seo ef-8fd ef-Sgdb ef-Ship ef-Six ef-Sjr ef-sorm ef-Spro ef-8sm g2ao g2bm g2ex g2kf g2lz g2nh g2ny g2od g2sc g2vq g2xv g5bq gh5br giby gibz g5hs g5ls giml gims g5qv g5us gh5uw g5ux g5vl g5wk giwq g5yk giyx g6bd géby géci gé6cr gégz xgb6hp g6i¢ g6nx g60o0 gépa g6qb gérw gésm gb6ut gévj g6vp g6wl g6wy g6xp eb6yd gbyv ei-lau ei-ldy ei-ligw ek-4yt el-laig em-smuk en-opt en-owim en-owr en-oyy xen-ocp eo-l8b ep-laa fm-skf fm-tun2 fq-Shpg fq-ocy ne-Sae np-4adz np-4xk nq-2kp oa-2ac oa-2rx oa-2uk oa-2rx oa-2yl oa-3uc oa-5bj oa-5dx oa-5h¢e oa-Tch oh-Gdsd oz-lar oz-2aw sb-lat sb-law sb-2ig sc-lai se-3cj wnp. (40 ea-jh ea-rx ea-th eb-dau eb-4be eb-4di eb-4fp eg-4ft ed-7ly ea-ar28 ef-Saxq ef-Sbtr ef-Xeo ef-Ser ef-Sgdb ef-8jf ef-lx ef-Sudi ef-Svu ef-vvd ef-Swb_ ef-xd ef-Szd g2gk ei-ldy ei-lew ek-4au ek-4rm_ ek-4uf ek-4yo ek-4yt em-sldg en-ozf ep-lae ep-lbv ep-lecf xep-lma et-lf et-tppt fm-ocup fm-ain fq-ocya fq-pm ne-Srg nj-2pa nm-9a nn-lnic nn-7nic nn-9nic hp-dug nq-2aq nq-5ay naq-5by naq-5cex naq-5fe nq-5fl nq-5ry nx-1x! oa-2aw oa-2be oa-2fp oa-2he oa-2hm ou-2jw oa-2ijy oa-2kr oa-2mh oa-2no0 oa-2ns 2re oa-2rf oa-2tm oa-2xr oa-2yj) oa-2Zyi oa-3byq oa-3¢r oa-3gt oa-3he oa-3hl oa-3ks oa-3ls oa-3my oa-3pm oa-3vp oa-inw oa-4wa oa-5by oa-5em oa-5dx oa-5ja oa-5jh oa-52p oa-5rj oa-5wh oa-5wr oa-6mu oa-6sa oa-Tbq oa-Tch oa-7dx oa-Thl oa-7lj oh-6bqh oo-laj oz-2ab oz-2aw oz-2ba oz-2¢a oz-2g0 oz-B8aj oz-3av oz-4ao0 4(oz-dav sa-az2 sa-dh3 sa-dq4 sb-lah_ sb-lai sb-laj sb-laq sb-lar sb-las sb-law sb-lbe sb-lbm sb-lbo sb-lbs sb-lid sb-2ab sb-2ad sb-2af sb-2ah sb-2 |! sb-2ay sb-2az sb-2bf sb-2bg¢ sb-2br sb-2ia sb-2ih sb-fp! sb-snni xsb-2ak se-lah sc-lai se-2ab se-lem se-2ea sg-a7 sp-cbl sp-jsl su-led su-leg su-2ak su-2bt. oz-2bp se-3ac meters ) oa-2cu oa-2kj oa-2sm oa-3cp oa-3lp oa-4dra of oa-3ax oa-3jk oa-4cg oa-5hg Oa-OXE oa-7jk 0z-2bo FE. O. Schwerdtfeger, S.S Margaret Dollar, KDUV woakg w6bhy woarb w6ch w6dkh w6dxt wSmi wirm w6alm w6bdy w6cut w6cyx w6dfm wé6dfs w6dnm wé6dwi wédwn wédwz wiar wiakv wiaik wialr wiou wisw w&bor whak op-lem op-ldr op-lhr. wc] whav] w6chn w6dlx wiac winr oz-2gp whacz w6avl whaoyv w6bah whasj wohl w6dkv wi7aax w7mo vedan wiep wYpl Ernest L. Petit, 8307 S. San Pedro St., Los Angeles, Calif. wlmk wlsi wlajx wlbeq wlemp wlkr w2apy w2agl w2art w2bfq w2bad w2baz w2aup w2as w2gx w2kr w2bip w2alu w3am w3jo w3aim w3bsj w4afk w4ix wirm wd4vx wh5uk wh5afx whiain w5aug wibat w5aih wipk wSajt wbda wkaff wSbbl ws w&Seqo wkcln wkdnf wSdkk wSdr wSus wIcub wiblw wiems wdzz wShd wicia wifqn wiaas wibd wSdzx waxu widd wiok wlack isc w9dqs Westfall, U.S.S. Postmaster, San Francisco, California w6dx wé6ut w6eh w6hto wé6bow w6eu wé6ard wine wimf witu w7zx wiajz WIBYV, W. W. Smith, 300 Edgell Rd., Framingham Center, Mass. eb-4bn ed-7izge ef-8bf ef-Sct ef-Sdmf ef-Sfd ef-Ship ef-8hpg ef-Six ef-8jd ef-Sjr ef-Sorm ef-Spro ef-Srpu ef-Srrr ef-8sm ef-Swbh g2bm g2fn g2kf g2nh g2od g2s g2xv g5br gh5by g5bz g5ls giml g5ms g5qv g@ivl @wiwk edyx gefdr e6hp eéqb géqj réut vivp g6éwl g6yv ei-lau ei-ldy ei-lpo ek-4jl ek-4yo ek-4yt em-smuk en-ovn ep-laa ep-lae fk-2ms fo-a3z fq-Shpg na-7mn qn-2kp oa-2bb oa-2rx oa-2yi oa-3ce a-3¢r oa-5he oa-5wh oa-5wk oa-7mn oa-7lj oh-6elj z-2ac oz-2ak oz-2aw o7z-2bg oz-4aa_ sb-lat sb-law sb-2ab sb-2ar ac-lah ac-lai ac-3cj xen-lbd x-izz. W. Douglas Farenholt, c/o wal wiad w6bp winj wld. whya wieh ef-Sadb lve N. Haltwanger, Pettit Barracks, Zamboanga, P. I. w5aq w5auz wdhv w6adv w6agr wé6als w6avd wéh6avj w6byvm wb6bvx w6cxi wé6ezr w6djq w6dmt winw wé6abg w6ap w6awa w6cih w5mx w6am w6avz whcem whdea wé6deq w6dnm wé6dnw w6acg w6efe w6cu wé6hm wéaf wi7acx wiacvy wiaix wiajb wibb wiun wSem ec-lax ac-lbs ac-leb w5ao w6adk w6aux w6bijd w6cuh w6dhg w6eah w6ue will walx whacg w6asm w6bfp w6cjv w6dgv w6dvg w6tj wigj ward w6ax wb6cis w6dfm w6drj wé6ru wibm ac-l tb In QST It Identifies You and Helps Q S T

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sorm g2nu £5hs rowk x6hp g6vj lew i= yy shpg \-2rx -5he -law aS) dkv “ax jmo San Ow Tt tu nh ms ryut ivo i3z elj aw [EXTRA] THE NEWS EXTRA VOL. 1 NOVEMBER, 1928 NO. 3 Extremely Com- pact Equipment Comprises the Best of New, Improved Parts The new REL shielded transmitter is a radical departure from all other kits on the market. The advantage of shielding is universally acknowl- edged. The black crystalline finish metal cabinet presents a most pleas- ing appearance not usually found in a transmitter. New REL equipment specially designed for the 1929 bands is employed thruout. The construc- tion is remarkably rugged and em- ploys standard circuits. Who Uses REL Apparatus: REL equipment is utilized by the leaders of the radio world. In far flung corners of the Globe, you will find REL kits and products Here’s a partial list of REL users. U. S. Army WMCA- New York City U. S. Navy WCAP— Washington U. S. Marine Corp WAAM ~— Newark U. S. Coast Guard KDYL—Salt Lake City General Electric WFBR—RBaltimore Radio Corporation of WRNY—New York City America KFH— Kansas Westinghouse KFPW — Missouri Firestone Tire & Rubber KFJF-——Oklahoma City Co WKBS-— Illinois WOR—Newart WJAS— Pittsburg New Transmitters in Metal Cabinets Shielded and Stable--Best for 1929 Features of Construction Described in Detail REL Shielded Kits may be used for any 7'2 or 75 watt Hartley, tuned plate, tuned grid circuit or any variation of them. The cabinets are electrically welded, in- suring absolute contact on all sides. The panel of aluminum uses a wood base board and the panel and base board slide into the cabinet. These cabinets are of uniform height and are exceptionally well adapted for M.O.P.A. circuits using a 7% watt oscillator with a 75 watt amplifier. Two cabinets side by side present a very neat appearance besides affording complete shielding. The top is detachable affording easy access to the interior. The sides are ventilated so there is no danger of the equipment heating. THESE KITS ARE THE ONLY ONES IN THE MARKET, WHICH ARE CONTAINED IN A METAL CABINET. The 7% watt kit is furnished with a new type No. 187 variable condenser and the new type No. 182 interchangeable plug-in coil. The 75 watt kit uses the large type No. 149 condensers and the old reliable type No. 127 inductors. Weston meters are used in both kits, with other quality apparatus. WRITE FOR FREE DATA Radio Engineering Laboratories 100 Wilbur Ave., Long Island City, New York Say You Saw It In QS T It Identifies You and Helps Q 8 T 53

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“ Allen-Bradley ) Resistors for Experimental Work in Television Bradleyunit-B [ ire doing experimental work in tele- use Allen-Bradley resistors, both fixed and variable. Bradleyunit-B is the ideal fixed resi )r resistance-coupled amplifiers as plate- cour resistors and grid leaks because: | stance values are constant irrespec- f voltage drop across resistors. rtion is thus avoided. 7) lutely noiseless. ng after long use. sate current capacity. i, solid-molded construction. rw a Ww soldered. oun \ (5 / Radiostat Th rkable graphite compression rheostat, and r types of Allen-Bradley graphite disc rhe provide stepless, velvet-smooth control for ng disc motors. La boratory Rheostat Types 10 — for general laboratory service. Capa 200 watts. Maximum current 40 am- pere \ handy rheostat for any laboratory. Write for Bulletins! SRADLEY CO., 277 Greenfield Ave., Milwaukee. Wis | Allen-Bradley Resistors Say You Saw lt In QS 11 It Identific You and He Ips ace2ek aec-2nr ac-Yaa ai-2kt aj-jkzb aj-jxix am-3ah eb-4ft eb-4kb oa-2me oa-3hl oa-3ls oa-3wm oOa-3wes oa-5bw oa-5by oa-Tew od-ljr od-2ab od-3bk « d-4dar k6adh k6éakge k6avl k6bde k6bhl k6boe k6buh k6bxt k6ch k6édp k6dri k6dvg w6dwr I. A. R. U. News (Continued from Paqe 45) Radio Society of Great Britain is a neces- sary condition for membership of the Union, though there is no official connection be- tween the two organizations. Up to the time of writing, 29 transmitting licenses have been issued in Northern Ireland, the majority of these being for a maximum in- put power of ten watts. In the past, most of the operating has been on 45 meters, 23 meters being used by about 6 station and 32 meters by about 4. The 90-meter wave has only been used rarely in the last few years. “T shall now mention very briefly some of the achievements of the GI stations. “In the summer of 1925, 5NJ established the first amateur contact between Ireland and U.S.A., and a few months later the first direct communication of any sort between Ireland and Australia was established by 6MU. Some time later, 6YW made a con- tact with Porto Rico, using 2 watts input, which was probably at the time a record for low-power DX. Since then, several dis- tant countries, among them Indo-China and Jamaica, have had their first contact with the British Isles through GI stations, and we now have three members of the W. A. C. club (2IT, 5NJ and 6MU). “In the R.S.G.B. QRP Tests of November, 1926, several GIs were near the top of the list, 6YW achieving the honor of being first in the British Isles. Special mention should also be made of 6TB, to whose painstaking the success of our Union is mainly due, and also of 6YW’s recent work as honorary or- ganizer of the R.S.G.B. Contact Bureau, an experimental organization whose work is al- ready beginning to bear practical fruit. “So much for the past. As regards the future, it is rather early to say much about the probable effects of the changes result- ing from the Washington Conference. The conditions of operation will be as set out in the memorandum recently issued by the P. O. in London, except that the addition of the letter I to the British prefix G has been sanctioned for stations in Northern Ireland. gi2BX becomes GI2BX, and so on. The general opinion seems to be that the new conditions are not at all bad, and it is likely that a good proportion of the GI sta- ticns could operate under 1929 conditions with only slight improvements. It is prob- able that most of the operating will be in the 7 mec. and 14 mc. bands, though several stations intend to try 28 m c. in the near future. —E. Megaw, GI6MU.” oOcP The many American and foreign amateurs who have worked this station will no doubt be glad to have some words from the chief operator regarding the origin and develop- ment of the outfit. We are sorry that “under cover” operation makes it impossible QS 1

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« Gbxt Ce@sS- ion, be- the nses the in- t of 23 1 32 has ars, > of hed and irst een by on- put, ord lis- ind ith ind Cc. er, the rst ald ng nd an al- he ut It- he in Performance that Challenges the World! Remarkable Federal Feats A Federal Radio operated by an amateur in the crow ded New Jet sey broadcasting area established a W orld’s record for DX reception when verification from 607 stations n all parts of the W orld were recelvc d. Licensed under patents owned and or controlled by Radio Corpora tien of America, and in Canada bv Canadian Radio Patents Lid sonic reproduct Say You Saw ederal ORTHO-SONIC* EDERAL’S engineering accomplishment, in producing the F11, has won the recognition and commendation of radio ex- perts everywhere. Without question it out performs any radio re- ceiver ever before placed on the market. Antenna and ground operation with four stages of tuned radio frequency, detector, and two stages of amplification brings in the weakest of radio impulses picked up by the antenna and provides phenomenal distance range. Every part of the set bespeaks itself of precise standards of engineering and skilled workmanship. Every unit, including the individual tubes, is fully shielded. The chassis is all metal -the cabinet genuine mahogany. Prices, without tubes, for battery operation $145; for light sock- et operation with Federal’s power-tube coupler, 60 cycle, $220; 25 cycle $245. (Slightly higher West of Rockies. ont - 7 . ’ {sk the nearest Federal Retailer for demon strat:on or write for complete specifications FEDERAL RADIO CORPORATION, BUFFALO, N. Y. OPERATING BROADCAST STATION WGR AT BUFFALO Federal Ortho-sonic Radio, Ltd., Bridgeburg, Ont. Radio ¢ Federal’ fundamental exclusive development making possible Ortho- s patented under U.S. Lettera Patent No, 1,582,470 It In QS 1 It Identifies You and Helps Q S T

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\ lio Engineering Is Not Sold on Newsstands ss & eS eS Ce Se Se SF eS eS eS ee eee eee ee ee R 5 New York City. | . $? bscription; $3.00 for 2-year S sample copy. PI NAME AND ADDRESS ] ess has been tube as a detector, in ) and use of a constant- as “The Engineering Detection with the Screen-Grid Tube slow torv. oscillator k classification ) Professional Technician Anything else Set been released on the use functions very efficiently. r issue of Radio [ngin- first-hand laboratory in- screen-grid tube’s de- ns will be tound. will be \lathematics of Radio,” Builder very Say You Saw It In QST — It Identifies You and Helps Q S T to give the name of the ship or operator, but as stated, cards and reports may be addressed through the Dutch Section of the I.A.R.U., or through the A.R.R.L. “For over one year’s time now, with more or less regularity, xen OCP has been on the air and much pleasure has been derived by working many amateur stations. The op also pounds brass on a 2 kw. 500-cycle quenched-gap spark set on 600 and more meters. “The works were started with the most friendly cooperation of three New Orleans amateurs, 5QJ, 5HR and 5UK, to whom xenOCP had been introduced by the Com- munications Department of the A.R.R.L. For the plate supply, a baby motor-genera- tor was chosen, and the first tube was a one- dollar receiving tube, one of the items se- cured in your famous 5- and 10-cent stores! However, it soon became fed-up with its transmitting duties and retired. “Back in Holland, the ship was exchanged for one circling Africa and a Philips 10- watter came on duty. In its present form, the set consists of a loosely-coupled Hartley circuit, housed in a small cabinet, with the coils, mounted on glass rods, on the top of it. It is grounded to the ship’s earth and the aerial of spark set is used for the short waves also. This aerial is an inverted L type, two wires of about 80 meters each. The wavelengths in use are 32 and 19.6 meters, with optional 341% and 44 meters, of which the 32-meter has proven to be the best. The m. g. gives about 300 volts, while the Philips 10-watt tube takes 60 milliamps. The receiver is a conventional O-V-1 (de- tector and one-step—A.L.B.) in shielded cabinet, to which a Telefunken screened-grid valve will soon be added. “Along the east African coast, western NU stations can be heard best from 1330 until 1430 GMT, eastern NUs at about 0400, and most of them averaging R3-4. QRN, however, is very troublesome. After 2000. many Europeans are coming in ok on the 52-meter band, especially the EF's and EBs. eb4FT is the most consistent of all. “In Durban the writer met with a very kind reception on the part of many FO hams, who attended the yearly convention of the S.A.R.R.L. “xenOCP, whose QSL address is: Dutch Section, I.A.R.U., Noordwyk aan Zee, Hol- land, is always anxious to work amateur stations and glad to arrange schedules and tests, when these do not in any way inter- fere with his professional duties.” GERMANY Germany is one of our national sections which is on the “honor list” by reason of having appointed an official correspondent and forwarding reports regularly each month. “The most important event during Sep- tember was our meeting during the holding of the annual Radio Show in Berlin (An- nounced in last month’s issue—A.L.B.). Among the many hams who attended we had the pleasure of being host to eg6FI, TI

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he by Op le st m i= L. po = ts

Say You THE AMAZING NEW

Hand aod Eve must evnchronize in testing the Elkon EBH Rectiber

FLIKON RECTIFIER FOR 66m 99

ONLY 200.000 AVAILABLE THIS SEASON UST as the Elkon dry, low-voltage rectifier revolutionized the design of chargers “ and “A” Eliminators, the new Elkon “*B” type Rectifier will revolutionize the design of **B’’ Eliminators. The Elkon EBH Rectifier plugs into any Eliminator using the former standard “B” rectifier tube. Simply take out the fragile 1,000 hour tube—plug in the husky Elkon EBH and the change is made. No changes in wiring—no adjustments. It is sturdy, solid, dry—has none of the frailties of a tube—not affected by acci- dental overloads or line surges. It is self healing. The power is smoother, quieter. From the orders already received from dealers and jobbers in all parts of the country, we know that we will be tremendously oversold this season—only 200,000 of these revolutionary rectifiers will be available. The elaborate manufacturing, testing and aging cquipment necessary to pro- duce the Elkon EBH Rectifier precludes any greater production the first year. Look for the Red and Yellow display carton on your dealer's shelves. The new EBH is packed in a metal can. Buy one from your dealer today! Plug it into your “B” Eliminator—Trouble free for at least 5.000 hours! Saw ItIn QS T It Identifies You and Helps Q S T

rae . 7 ro? a NJ Ae ELKON, »» PO sg Division of s s*s P. R. Mallory & Co., Inc. FF e i & OS 350 MADISON AVE. } SF i NEW YORK CITY i Y , ELIMINATORS

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Dubilier TRANSMITTING CONDENSERS UBILIER type 686 condensers have the usual Dubilier higi. factors for use in transmitter net works. 1000 volt DC rating. safety filter May be connected in series where the working voltage exceeds 1000. Through series parallel connections practically any working voltage and can be obtained. capa DC voltage must not exceed 1000; or in A.C. supply filter circuits the trans- former voltage must not exceed 750 volts per rectifier plate. 1 mfd. condenser $5.00 2 « $8.00 ver” Dubilier CONDENSER CORPORATION 10 E. 43rd St. New York City Reg U.S. Pat.Ofe. Say You Saw It In QS 7 from London, et2UA, from Riga, and ekDCZ, Herr Johnske, the operator of Count Luckner’s Vaterland on its visit to America. (And well-known as ‘Fritz’ to many West Coast U.S.A. hams, too— A.L.B.). “Since last month, DX conditions have not changed very much, and there is little to report in this direction. “We are pleased to state that eg6PP and eg6FY have become members of our society, the D.A.S.D., their licenses being DEq831 and DE@s852. We welcome them heartily and hope that others will follow their ex- ample. “There seems little doubt that after Jan- uary, 1929, we will be given new interme- diates. We regret highly that it is necessary to give up our old and better system of inter- mediates. With them it has been very easy to identify the continent and country of the identify the continent and country of the transmitter. We also regret that it is not possible to get private transmitting licenses, and hope that by the end of the year we shall have good and favorable regulations to this end. 73’s to all. FE. Reiffen, See’y, D. A, S. D.” Standard Frequency Transmissions From WWV (Continued from Page 42) quen_y to ke transmitted is then given. There is then a four-minute interval while the transmittnig set is adjusted for the following frequency. Information on how to receive and utilize the signals is given in the Bureau of Stand- ards Letter Circular No. 171, which may be obtained by applying to the Bureau of Standards, Washington, D.C. Even though only a few frequency points are received, persons can obtain as complete a frequency meter calibration as desired by the method of generator harmonics, information on which is given in the letter circular. The schedule of standard frequency signals is as follows: East. Standard Nov.20 Dee.20 Jan.21 Feb.20 Mar.20 Time (P.M.) 10:00 10 :08 1500 100 125 550 1500 10 -12—10 :20 1700 1200 150 600 1700 19 :24—10 :32 2250 1400 200 650 2250 10 :36—10:44 2750 TOO 250 S00 2750 19:48 10:56 Yao 5000 300 1000 oe50 11 :00-—-11 :08 3200 5500 375 1200 3200 11:12 11:20 3500 5700 A50 1400 3500 11 1—11:32 1000 6000 550 1500 1000 ) The figures given above are frequencies in kilocy les Experimenting With Bypass Condensers (Continued from Page 38) same time not bypass excessively the upper audio register, that value of capacity is best for the purpose. The following figures show the degree of bypass of radio fre- quency signals using the same audio fre- It Identifies You and Helps Q S$ T

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en. ile the ize nd- be of gh ed, Icy od on $6.00 will be in force. Last Chance for Special Low Price! The Radio Manual is about to be published. $4.95 must be definitely withdrawn on November 15th—after which the regular price of The special advance of publication price of Order immediately to take advantage of this unusual saving. Radio Operators! Are you prepared to use the new International “Q” signals which go into effect January 1,1929? Do you know the correct procedure for obtain- ing a radio compass bearing as prescribed by the terms of the International Radio Telegraphic Convention, effective January 1, 1929?—the right procedure when distress communications are ended and silence is no longer necessary ?—what to do when you hear from a radiotelephone station the spoken expression Mayday? These Questions and Thousands More Are Answered In THE RADIO MANUAL A Complete Handbook of Principles, Methods, Apparatus for Students, Amateur and Comercial Operators, Inspectors By G. E. STERLING, Radio Inspector and Examining Officer, Radio Division, U.S. Dept. of Commerce. Edited by ROBERT S. KRUSE, for five years Technical Editor of QST. Complete Preparation fo Elementary Electricity an Magnetism Motors and Generators Storage Batteries and Chare- wz Circuits Theory and Application of t Vacuum Tube Fundamental Circuits Em- ployed in Vacuum Tub lransmitters Modulating Systems Em loyed in Radio Broadcasting Vavemeters, Piezo-Electri« Oscillators, Wave Traps and Field Strength Measuring Apparatus Marine Vacuum Tube Trans- mitters including detailed lescription of Model ET-3626 %. Radio Broadcasting Equip- including, for first time in ment including, for the firs any text book description and time in any text book, th circuit diagram of Western complete equipment of West- Electric Superheterodyne Re- ern Electric 5 Kilowat ceiver Type 6004C broadcasting Transmitter 13 Marine and Aircraft Radio used in over 75% of Ameri- Beacons and Direction Find- ean broadcasting stations Are description of Federal Marin 2 Kilowatt Are Transmitter plete details of construction, Type AM 4151; also model operation and licenses. “K” and “Q” Radio Laws and Regulations 11 Spark Transmitters includ- of the U. S. and Interna- ing @escription of Navy tional Radio Telegraph Con- Standard 2 Kilowatt Tran vention. Quotations of all mitter important sections » Commercial Radio Receiver 16. Handling and Abstracting and Associated Apparatu Traffic r Government License. 16 Chapters Covering ers. The Development of Amateur Short Wave Apparatus. Com- Transmitters includins 14 Examine It Free Order On This Coupon ; D. VAN NOSTRAND CO., INC., 8 Warren St., N. Y. 8 8 Send me THE RADIO MANUAL for examination. . . - - - or l P oT a2 N ’ # Within ten days after receipt I will either return Spec la rice Ou the volume or send you $4.95.—-The special advance 1 Boor cone , , ' The Radio Manual” will be ready in a few days ' 4 Over 900 pages bound in flexible Fabrikoid. Regular § Name , ccssecccs @ price after publication will be $6.00. Orders re- ' (QST 11-28) § ceived now will be accepted at the special advance 8 St. and Number cbs eueees ' Price of $4.95 Send no money now. Examine the ' ry book first Pay or return in ten days. ° City and State ............ -§ Say You Saw It InQsT It Identifies You and Helps Q S T

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How’s Your will be a tion nd along with operation. the others, preserved ina Note the wire fasteners Unnecessary to mutilate pies. Opens and lies flat in any position. One-fifty each postpaid togeth and protect them for And OST Library? y will be constantly referring to — the series of articles by Ross Hull on the work of the A.R.R.L. Tech- nical Development Program. There textbook for 1929 construc- These issues, should be A binder will keep your QSTs always future use. 2 good-looking binder, too. 1711 Park St., Hartford, Conn. Say You Saw It In QS T quency transformer, but bypass capacities ranging from .005 ufd. to .002 ufd. and carrier frequencies of 15, 33, 100 and 1000 kilocycles. 15 Ke. 33 Ke. 100 Ke. 1000 Ke, Percent Percent Percent Percent 00025 ufd, 22 38 57 65 0005 “3 38 55 76 g1 0006 i 16 63 80 R6 00075 ** 50 70 85 90 0009 “3 54 73 &S8 o4 .001 - 57 76 89 97 -002 ~ 60 87 97 100 From the above, we glean the informa- tion that the .00l-ufd. capacity is quite satisfactory for bypassing the radio fre- quency component remaining in the de- tector plate circuit after rectification. Since the frequency spectrum encountered in ra- dio broadcast reception lies within the 550- to 1500-Ke. band, the values obtaining on 100 Ke. can be considered as criterion. As to the extent of audio frequency bypass- ing, this value of capacity bypasses only 6 percent on 5000 cycles. Consequently, the selection and use of a .001 ufd. bypass condenser in the plate circuit is consistent with sound engineering principles. Now We're in the Air (Continued from Page 23) is about to happen, “Mac” may be counted upon to be there with the proverbial bells (or buzzers) on. He sized the thing up and got into action. Telephone and telegraph were out of the question as they were too expensive. Beside the expense, the installation of lines would take too long. Radio was the only solution but even that seemed rather costly —if they were to buy equipment and hire operators! “Mac” got in touch with Robert B. Par- rish, W6QF-W6PS, president of the Ama- teur Radio Research Club of L. A. and manager of the Pacific Engineering Lab- oratory Company, and explained the idea. “Bob” took to the idea like a small ham to a big bottle and put it up to the mem- bers of the A. R. R. C. They gave evidence of their hearty approval and made “Bob” master of ceremonies and installations but told him not to get too swell-headed about it because they expected to have much in- stallation and few ceremonies and that he was also expected to do his share of the work. He did. The stunt called for five complete sta- tions with their separate sources of power, as there was no power at the pylons. This meant sets, tubes, and batteries, for the most practical operation. Now radio clubs are not usually overstocked with any of these things, especially tubes and batteries, so “Bob” sent out a QRR via land-fone to various friends. George Walters, western representative of the French Battery Com- pany, came forward with “B” batteries for all transmitters and receivers, with each transmitter using 350 volts. The Durkee- It Identifies You and Helps Q S T

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ted }Is ind . Parts OR fifteen years Formica has been furnished in changing forms |) to suit the convenience of the radio engineer and producer. In the early days it was sold in whole sheets and whole lengths of tubing and fabricated largely by hand by the radio builders. Then there were decorated front panels printed in gold and silver. Now there are sanded or threaded tubes punched and cut to length; washers; shelves; sub panels and terminal strips most of them shipped all ready to assemble. At large expense Formica equipment has been changed from year to year to provide production in quantity at all times of insul- ating parts that would meet the requirements of the moment. And the quality and uniformity of the material has also steadily advanced. The Formica Insulation Company 4620 Spring Grove Avenue Cincinnati, Ohio ORMICA Say You Saw It In Q S T It Identifies You and Helps Q S T

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To Our Readers who are not A.R.R. L. members to become a member of the Relay League? We need you ization of radio amateurs, the iation that does things. From ‘7° you have gained a know!- of the League and what it read its purposes as set forth issue We should like to full-fledged member and add urs in the things we are \mateur Radio. You will rship edition of QS7 delivered month. A convenient appli rinted below—clip it out and n radio ts the only essen- ile mbership P. "FF SF SCF SF eS SC SF FF SF SF eS eS ee eee ee ee ee eS ee Relay League, U. S.A. membership in the Ameri- League, and enclose $2.50 ($3 ries) in payment of one year’s les me to receive OST for the ‘lease begin my subscription with issue. Mail my Certificate send OST to the following riend who is also interested in hose name you might give us a sample copy of OST? hanks

Say You Saw It In QS T Thomas Corporation sent two “Western” 6-volt storage batteries per set to the field each day, freshly charged. The Western Auto Supply Co. donated a whole flock of tubes of various sizes. All of these people said they would take Christmas cards in payment. How’s that for cooperation. “Bob” supplied the main transmitters from his laboratory, and most of the re- ceivers and the other transmitters came from the membership of the club. A period of feverish installation ensued, which began a short time before the races and ended a shorter time before the same. Licenses were finally obtained and calls assigned and most of the hard work was over. We are sorry to say, maybe, that some of the sets at the pylons would hardly take the Hoover Cup for looks. They made up for their appearance, however, by their per- formance. 6EMH, for instance, at Pylon Number 2, was a first class replica of my idea of what the first set looked like that belonged to the O. M. himself. The coating of dust was so thick that it actually was necessary to blow some off the meters to read them. But the set worked like a charm, as did the others in more-to-be- desired and less dusty locations. Tuned-plate, tuned-grid was used in all transmitters. At the pylons a short pro- jecting stick at the top served as a support for the antenna of No. 20 or No. 22 wire, while the counterpoise was run out to a nearby post or tree. Nails and tacks driven into dry boards were the only insulators. Receiving antennas were supported by trees, posts, and sticks stuck into th: ground, and ground connections were made to the pylon frame. Pictures of these instal- lations are not furnished herewith because they didn’t turn out good anyway, and be- cause they would be a source of too much pleasure for the opponents of the “lo-loss” postulates. However, it would not be fair to fail to give due credit to the very snappy job at 6EMF. the control station in the grandstand. This good-looking and efficient transmitter was a panel-mounted affair, artistically and mechanically balanced. Suitable engraving enhanced the glistenine black panels but, above all, the evidence of skilled workmanship stood out like a shining jewel. The only visible parts of the set were the specially-wound plate and grid coils, two good-iooking chokes, and _ the tube—in this case a 742-watter. All other parts were hidden behind panels. Visualize a busy afternoon. There are 50,000 people in the grandstands. A ver- itable hill of humanity is gazing at the immense field before it, listening to brief announcements, paging, wise-cracks and what-not, from the announcer over the public-address system. A huge array of Army planes is just over to our right, lined up near the fence, waiting to go on duty. On our far left the Navy is well represented by a detachment of planes and their de- tailed crews, seemingly always active. Far It Identifies You and Helps Q S T

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NATIONAL VELVET VERNIER DIAL TYPE N This four-inch solid German silver The tuning knob is of Bakelite and National Velvet Vernier Dial, type N when desired, a Bakelite apron will be has been developed for use in amateur furnished at slight additional cost for and other radio equipment protection against high requiring the utmost pre- frequency burns when the cision of logging. It is dial is used on high power equipped with a real Ver- appliances. Dial attaches nier making accurate read to the face of panel at ing possible to one-tenth of three points making ac- a division. The mechanism curate mounting ex- is the original and unex- ceedingly easy and sim- celled National Velvet ple. The type N_ dial Vernier design, approved is made with 3 different and used by transmitting styles of division, 100-0,

and receiving amateurs all Sereen-grid, short-wave 150-0 or 200-0. List Price receiver, a non-radiat- pe over the world. ing short-wave receiver. $6.50. Write today for short-wave bulletin No. 128 ST. NATIONAL RADIO PRODUCTS NATIONAL CO. INC. w. a reApY, PRESIDENT MALDEN, MASS. Say You Saw It In QS T It Identifies You and Helps Q S T

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In Stiff Buckram Binding The Radio Amateur’s Handbook Lies open and flat at any page invaluable Handbook attractive and dura- maroon leather cloth ers. Will Wear Like Iron. Price $2 postpaid anywhere A.R = Stiff Hart Conn. Binding Gen ) wanting a better bound copy of tk andbook for a long time. Here are vo dollars. Say You Saw It In QS T across the field, in a direct line with our little box on top of the grandstand, are the civilian hangars for visiting planes and non-contestants. Directly in front of the grandstand is a large white circle on the runway. This is used for parachute jump- ing contests, exhibitions of bombing and numerous other stunts. Running out to the circle from the fence is a connecting white line, used for the “dead stick landing” con- tests, up to which the winner, making a landing with a “dead” motor, came within three feet. Over to the left again, in front of the Navy planes, is another white line. Six planes are lined up along the line with motors idling, waiting expectantly. Adjoin- ing our “box seat” in the radio shack are two observers who tell us that Event Num- ber 3 is about to start and is a “free for all,” open to all types of ships powered with motors of 720 cu. in. displacement or less, but open to civilians only. The d's- tance will be fifty miles—ten laps of the five-mile course—and prizes will total $1,500. The operator at the headquarters station (6EMF) at our elbow sends out the following: “QST QST EVENT NR 3 ABOUT START FREE FOR ALL QRX RACE 6EMF.” He turns the dial between two points, about four “degrees” apart. He finds 6EMH., Pylon Number 1, at 54 on the dal. 6EMH says: “QST OK DE 6EMH AR.” He turns the dial to 49.5 and he hears 6EMI at Pylon Number 3 say “QST OK DE 6EMI AR.” He would find 6EME, Pylon Number 4, at 45.5, but they are not using this pylon in the five-mile race. Suddenly the starter twitches his flag and the racers roar toward 6EMH at ten second intervals. 6EMF sends another QST to all pylons: “THEY’RE OFF.” Let’s drive out to 6EMI and watch this race from there. The watchman at Pylon Number 3 has a big jar of ice water and there’s not so much dust here. Here they come! You'll have to look sharply be- cause...Good nite! He’s coming right at us! Let me get out of here.. here...No, you see he suddenly makes a vertical bank and roars around the pylon and is gone. Whew! That seemed close, though, especially from our lookout in the pylon. They travel comparatively close to the ground, only a few feet above it, and they appear to be attacking us. But we soon get used to that. Here comes a bunch. In four zooms and a sputtering roar they appear, roll over on their sides, make a ninety-degree turn, roll back again and are gone. We get so used to it that we don’t watch them any more, and we see that the watchman, relieved during the race, has gone to sleep in his car. Suddenly an observer calls: “Operator! Plane Number 159 fouled pyton! Sixth lap.” It Identifies You and Helps Q S T a

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our ' the and the - = We Think Y mp- e in ou and the : Ought to Know— a ught to now fa thin NE quality is an elusive thing—yet all- dealers and setbuilders how to build the important. We think you want to know such a “comparator”. Do you know of Six the truth about it—the whole truth. That is any other transformer manufacturer vith why S-M, in spite of having so much to talk who is doing that? If not, why is S-M ain about in the way of selectivity and distance the only one who is? * > “h- i ” i ry ss are range, keeps “harping” on tone quality. We SECOND: We are giving an absolute aang can og by emgecnenns | measurements and guarantee that the S-M Clough-System for curves, that the new S-M Clough system transformers you buy at $6.00 (list) aad audio transformers come closer to doing cannot be surpassed by any trans- on that than any others we have ever been able formers of the conventional type—not i's. to find, - any price. But then, any advertiser utilizing the Clough invention with the Ary h big claims, draw curves a its practical elimination of hysteretic ‘tal publish es ing that doesn’t necessarily distortion—at any price whatsoever. é rove anything to you. ers P y 6 fo) If you have a laboratory, with a good out But IT’S TRUE, nevertheless. One by one audio frequency _oscillator and sensitive we are getting reports of tests—made by high-frequency milliameters—by all means f impartial engineers for manufacturers and verify for yourself the sweeping claims we UT others who employ them—agreeing with our make. If you haven’t—then listen to one of CE own findings that there is nothing on the the public S-M comparator tests. If you can’t market to match the tone quality that you do that—just try a pair. Ask your own ears! ats build into an S-M set—or into any other We think you ought to know. (H. good set, if you so desire—by the use of S-M MH Clough system audio transformers. That’s In the chart below, E is the two-stage curve von what the engineers in the world’s largest for the ~_ —? oa ay - : , & . wl “= ro stage; and 226, 2nd stage, $94 each); is lon telephone laboratories said. It’s w hat the that of the smaller ones (S-M 255 and 256, $6.00 2» professors of an old New England engineer- each). Note the marked advantage over A, B, . ing school decided. and C—all standard eight and ten dollar trans- g at formers under equal conditions. In To the radio-wise public—those who decide, in the end, every question of com- lag parative merit in manufacturers’ claims—we ten offer to prove the absolute superiority of S-M - ST tone quality in any fair way you can suggest. Here are, for instance, the two fairest ways hi we know of—and we’re taking both of them: ris mm lon FIRST: We are building, and operat- si nd ing in the most public places we can ro ey find—the big radio shows, hotels, «| De- dealers’ show rooms—comparison am- a" tht plifiers which interchange instantly in S ah o¢ a circuit, on throwing switches, a set j a of S-M transformers and a set of any ‘ on other make desired. We are so well tesieniaadittias m satisfied with the sales of S-M audios rd r — » § this “hard-boiled” Are you receiving “The Radiobuilder” regularly? he esulting rom P is a os ule No. 5 (Sept.) described a Comparison Amplifier for to method chat we printed and distributed comparing audio transformers. No. 6 (Oct.) tells about 35,000 copies of an article telling the new “PA” Public Address System. To S-M Author- nd ized Service Stations, it comes free of charge, with all ve new constructional Data Sheets. If you build a ~- Ay = your SM ROUND THE WORLD FOUR on sionally, write us about the Service Station franchises. {Vv the broadcast band with these new S-M_ five-prong aus GEE GED 7 plug-in coils—131X for 190 to 350 meters, Prey 3 and Silver-Marshall, In > 65 ors. $1.50. Silver-} shall, Inc. “== Pb 131Y for 360650 meters, $1.5€ 858 W. Jackson Bivd., Chicago, U. S. A. ’t «++-Send your complete catalog, with he sample copy of the Radiobuilder. . 858 W. JACKSON BLVD. «++-For enclosed 2c stamp, send Data AS VER-MARSHALL, Inc., CHICAGO, - - U.S.A. | Sheet No. 4 on Audio Transformers. r! -h Address. .ccccccccsccccccccccscccccece 65 Say You Saw It In Q S T — It Identifies You and Helps QS T

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Be a Commercial Radio Operator A . that should en- ble average intelligence vernment’s theo- re ation given to ap- 1 Commercial Radio Nilson and Hornung’s PRACTICAL RADIO TELEGRAPHY 380 peces, Sx8, 223 ittustrations 53.00 net, postpaid s in detail the 1 operation of e modern, 1928, com- park, and vacuum er It furnishes commercial vers. It covers 1 elementary elec- tical operation Some outstanding points R Y mathematics; 2. A 1 or knowledge of in commer- ‘ ything n detail ; 4. ¢ t f self-examina- y y accurate ; { ring diagrams fore you pur- just this ase and mail | McGRAW-HILL FREE EXAMINATION COUPOH M Book Co., Inc., 3 Avenue, Ni Y me Nilson and Hornung’s PRAC- ) TELEGRAPHY, $3.00 net, postpaid. turn the book, postage prepaid, in 10 t at that time. val in the U.S. and Canada only) Q.S.T. 11-1-28 lunior Rheostats it a master instrument. Ask your w you the exceedingly fine adjustment mooth action. Diameter, 1 7/16 inches, *, positive acting switches for Junior Pore rrerrer Tre TIT TTT TTT 40c RESISTANCE UNITS Here you need absolute dependability and Yaxley Resistance Units. Run true nvenient screw eye and soldering lug easy mounting. Filament .and grid O OHMS cocccccccccces 15c to 40c MFG.CO. Dept. S, 9 So. Clinton St., Chicago YAX 66 Say You Saw It In Q S T — It Identifies You and Helps Q ST The operator at 6EMI calls 6EMF at the judges’ stand. As the latter is always in a continual state of “QRX” and is watch- ing for information to flash to both pylons at the same time, only a few dots and dashes are necessary to raise him. He replies: “6EMI R K”, and the following conversation takes place: “PLANE NR 159 QFP (Fouled pylon) LAP 6 HW.” “OK QRX.” In about a minute: “6EMI DE 6EMF PLANE NR 159 DISQUALIFIED AND FLAGGED OUT NM QSU.” 6EMI answers: “E E,” and the watch is continued. The unfortunate pilot of Plane Number 159 who misjudged the distance around Pylon Number 3 was saved the trouble of going the last four laps. He was flagged out of the race almost within a minute after passing Pylon Number 3. And so the race goes on. Few accidents marred the races so that the use of “QRR” for “crash” was rare. But the radio spoke of other things beside “QST TON” (Take- off numbers), “QFP,” etc. Transportation was arranged for. Observers at each pylon were given detailed instructions. One day a fire was reported by means of pylon radio. Lost planes were located. An ob- server had a “date” in Glendale at a certain time, so what was the earliest time he could leave? When do we eat? How many more races are there to day and will they move Pylon Number 4 again after they get it up? Which foot were you using that time? QSD? And a thousand other things of varying importance. After the first two days or so the novelty of the thing wore off, in spite of the diver- sified program. But the efficiency of the service remained above par throughout the entire period. Chairman W. L. Schaffer of the Race Course Committee was asked how the radio had been. He replied: “The radio is O K. I am very much pleased with it.” And that, as an expression of the race officials, may serve as a hint as to the satis- faction derived from the accomplishment, by all parties concerned. Se 160 Meter Low Power Transmitter (Continued from Page $7) key and, listening on your own receiver for the signal, turn the dial of C1 until the wave is within the legal band. Then adjust C2 and the taps on the antenna inductance until the 25-watt lamp in the primary of the plate supply transformer glows at about medium brilliancy. At this point, which is a sharp one, the two circuits are in resonance with each other. The transmitter is now in 8 working condition, so open the key and listen on your receiver for some station’s signals. Then put the completed station m operation by calling the station heard. Signa Code Belde

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and He wing ‘lon) race itis- ent, Bradley Leak, ? 95 absolutely noise- jess and stepless, 2000 to 30,000 ohm re- EDS tees Hho Horne of 45 VESEY STREET NEW YORK* densers, double spaced fortrans- Cardwell con- 3 45 pemee. " ist 6%, mitting, .00025 cap. special $2.95. New York’s Headquarters for .. 19 mnameled copper wire 4. Bradleystat No. B-210 - Transmitting > Apparatus ” Qa BRM, Gh cocsccess ” $.01 — lik aad ; When in Town Visit Our Store No. 10 Enameled copper wire, Full Line of Acme -- Thordarson -- Jewell --Flech- *%” length, ft. ....+++-- 01% theim -- General Radio -- Signal -- Bradley Genuine Bakelite Panel 10xl4xz% ..... cocccccececce 1.50 SPECIALS Baidwin phones type C, pair 5.95 Dubilier Mica Condenser .002 cap. 6,000 working volt 1.95 signal Buzzer Set internattonat General Radio 247D .001 cond. plain or with vernier 1.75 —_ igh Sg ™ Code on Baseboard ....... $2.45 “ne a ee en ee ee ee 1.35 MOUMEINS APS oo ee see. ie Belden braid % inch wide, ft. .06 Dubilier cond. .5 mfd. 1,000¥ D.C. working voltage -85 R.C.A.—U.V. 1716 Super Het. transformer 1.45 /_ Ward Leonard Resistances; fits ——— bass receptacles; 2 1 i of A fA 7. A 6—"'R”’ . sizes 300—600—900—1200 and 2000 ehms A “ ‘anahcemsat "’e soak $15. Imported German head sets; very sensitive 3.45 " - side of centre tap. ....2.45 Honeycomb Coils unmounted, all sizes in stock at % price cits $8 Signal Corp adjustable arm micro-transmitter for Ward Leonard Resistance panel mounting 2.45 | $4.75 list-6% inch long—800- $9. Dubilier condenser, 4mfd; 600 v. D. C. working type 2.95 1000 -1200 -3000 -6000 -8000- 903; limited quantity 11000 ohms; can be ed for Acme 500 w. plate trans- R.E.L. Transmitting Inductances,per set. 8.80] 2-50 watt tubes or less, $1.45 former, 1000-1500-2000 each Bristol 50 Henry choke 2.75 side of centre tap, 24.00 6.50 Acme .0005 enclosed condenser -95 Acme B.H-1 transformer. 255-510 each side of centre tap; also 2 fil. windings of Pyrex Low-loss V.T. Flechtheim Condensers, . 4 v. each side of centre tap, sockets, each 39c. all types 35% off list Television disks as specified $10.25. in QST special $1.95. Acme C.W. 30 Henry choke General Radi f 58 8 $18 list — 150 M. A. single VAR E Wave Meter, 10 to 225. — $14.40; also other sizes at ARIABL ters, list $22, special $14.50 special prices. RATIO { , POTENTIOMETER AUDIO FREQUENCY ; NEO GLOW RANSFORMER i ACME nrrostat T i LAMPS Get any ratio you want. A combined Pot and Made by General Electric flament Rheo. SPECIFICATIONS Co., type G. 10, standard 6 ohm rheo-100 ohm pot Type V A-2 Ratios Available =e soon Sen ‘oe 30 ohm rheo-100 ohm pot Primary Secondary Primary Secondary Le oe uses, as illustrated 30 ohm rheo-300 ohm pot. Binding Binding Binding _—“y ~———F in QST May issue page 17 RATIO Posts Posts RATIO Posts Posts ——— Price onl 656 TWIN RHEO for low ot 25: 1-4 5-6 4.25:1 1-8 5-8 —_ y sesusoennts voltage tubes. List $3.00. Special each 65¢ 1-3 5-6 4.75:1 1-2 5-7 1-4 5-7 5.25:1 1-2 5-8 1-4 5-8 7.5:1 2-4 5-6 ADIO 1-2 5-6 9.5:1 2-4 5-7 ACME TRANSFORMER 13 57 USA 24 5-8 OD FOUN- On the primary side the binding post ir DATION é use having the higher number should be con Listed at $5.00. The unt O Y nected to the B+ and likewise, the second TRANSFORMER ; — w ) ary post having the higher number should t = ; “ — a _ ws 7 a grid. gher numb cue ot ame. gf McCullough A. C. tubes. Will ; pence ee - By using binding posts 3-4, still highe camry © tubes or its equivalent—2%-3-38% ted quantity at $1.10 ratios may be obtained if desired, but the Y- List $6.00 Special - $2.25 above selection will usually fill all require ments, ACM CHOKE Other specific ~—_ similar to type A-2. Price $7.00 each COIL Special ea VARIABLE s A high quality choke 1/10 h FILAMENT a ee Henry at 100 mils. GENERAL RADIO Pap pacts List $5.00. Special $1.25 POWER AMPLIFIER TRANS- ¥ M | FORMER Px GENERAL RADIO and “B” ELIMINATOR KIT Ns All necessary wil Type 285 AUDIO parts: operates 125 watt—110 volt—60c. tapped at-4-7- from 105 to 125 10-13-17-20-24-30 volts. Limited quan- TRANSFORMER volts A. C.— tity. List $19. gives “‘A’ “*B’’ and “Q"— for SPOcial 2... eee cece cece eee eeeeenes $4.45 Ideal for high and amplification and f é —" for set. even amplification. Type 390 uses type 280 tube lo carry ¢ . Tyve 285-12—6 te 1 a a om We arry a stoc ol Type 285-D—3.7 to 1 “R. AH’ Raytheon tube. List $50 — aoe aah ik of Snoctal 48 _ $19.50 GENERAL RADIO PARTS List $6.00 Now only $3.25 in the country MAIL ORDERS FILLED SAME DAY 10% Must Accompany All Orders Say You Saw It In QS T - It Identifies You and Helps Q S T

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Martin's Latest and Greatest Bug THE Great vw YWIBROPLEX No. © The smooth- est, easies t- working bug onthemarket, Not too fast not too slow— but just sensei an right. Works arn Base $17 where others ickel-Plated $19 can’t. Fam« us Impro\ ed Vibroplex Ile th erator per Japanned Base $17 t Nickel-Plated $19 Special Radio Bug with Extra Large, Heavy, Specially ted Contact Points for direct relay ° : . B - tt Genuine Vibroplex. The Vibroplex Name- Remit by Money Order or registered THE VIBROPLEX CO., Inc. “VIBROPLEX’ 825 Broadway New York City e Address: New York That Satisfies TONATROL Trade Mark A Complete Line of Yolume Controls Smooth, gradual control of Inten- , under all conditions will be your reward if you incorporate the Tonatrol Volume Control in your eceiver. Tonatrols are variable esistors of the famous Royalty type, ially designed with the re- juirements of different circuits in mind. Furnished in standard types or with battery switch or power witch attached. From $1.50 to vo “a iT TONATROL Controls for all Radio Purpeses. Electrad specializes in a full line of Controls for all Radio Purposes in- iding Television. Write for FREE Hook-Ud Circulars Dept. T-11, 175 Varick St., New York Say You Saw It In Q S T — It Identifies You and Helps Q S T Official Frequency Stations NE cannot have read QST during the past few months without realizing that there are many changes to be made in amateur conditions when the effects of the International Radiotelegraph Con- ference is felt after the first of January, 1929. Under these new conditions it will be impossible for us to go along with our old opinions concerning the amount of accuracy that is necessary as far as the position of any signal in the frequency spectrum is concerned. We have in the past been speaking in terms of wavelength and in accuracies of 2% in our - Official Wavelength Station work. These will not do for 1929 and some major changes must be made in the require- ments which these stations must approach. QST has contained sufficient material on the reasons for referring to the position of a station in frequency rather than in wave- length to make a further discussion of this subject unnecessary. We, therefore, im- mediately find that we must give all reports in frequencies and the operators of these stations should make a distinct attempt, particularly during the next few months, to not only give official reports in fre- quencies but to adopt it as their unit of measurement and to learn to actually think in frequencies. About the quickest way in which this can be accomplished is to cali- brate your present meter in frequencies and to put the wavelength calibration at the bottom of the biggest pile in the darkest corner of the shack—better still, destroy it. When we change to the use of frequency the name which this service has borne be- comes incongruous and even though senti- ment may prompt us to hold on to an old friend, these echoes of the past are danger- ous to our future and we will be much better off by starting from scratch. In accordance with this, stations in this service will hereafter be known as Official Fre- quency Stations or O.F.S. Our new bands will be materially nar- rower than are our present ones and an accuracy of 2% as has been demanded in the past is entirely inadequate. Our old 40- meter band, for instance, will extend from 7000 to 7300 kilocycles and 2% of this band amounts to 140 kilocycles. There Is, there- fore, a band of only 20 kilocycles in the center of this band in which a report indi- cates that the signal is within the official limits of the band. In other words, if a report on a signal is given that is not be- tween 7,140 and 7,160 kilocycles, the oper- ator receiving the reports is not sure but that he may actually be outside the limits of the band. What is worse than this is the fact that with a 2% accuracy, no report can be given which indicates definitely that a signal is within the 14,000-kc. band as it will be in 1929. It is impossible for us to obtain with this type of service a degree of accuracy which would be desirable and so it remains for us actly celv have meni in th volt illur 2}: pea have THE COR Powel

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If your radio doesn't operate a power speaker it’s obsolete pa, as a poe eT

This is the worldS lowest priced AC Electric power sp \Eur=ooyNf Here is a radio designed ex- actly as the most costly re- ceiver. New features. that have marked radio advance- ment this year are incorporated in this 1929 set. The improved AC tubes! Shielding! Low voltage that promises long life ‘t9 tubes! Volume control! \luminated dial! Power 2|:peaker operation! And Cros- ley manufacturing methods have kept the price LOWEST of any genuine electrically operated radio. Crosley econo- mies in production and mar- keting are directly responsible for the unmatchable price of $65. Crosley radios are out- selling any others in every market. Sales nearly four times as great as last year’s record breaking year, indicate the VALUE the public is find- ing in this latest Crosley suc- cess. THE CROSLEY RADIO CORPORATION Powel Crosley, Jr., President, Cincinnati, Ohio The Improved MUSICONE the fastest selling magnetic loud speaker at $15 G

WITHOUT operating the new dynamic ~ power DYNACONE 25 You have tore for you e amazed for $25

The FIVE DAY FREE TRIAL offer is copied on every hand but let any one deter you from comparing the Crosley with ANY set made. You need not be a radio expert to judge the VALUE Crosley gives you. Be sure you have the new Crosley dynamic For the first time popular price field its deep, resonant tone from dynamic power available is a speaker at $25. power speaker. No one has even imitated it.

a surprise and a treat in You will delight in the and beauty of its tone. BOX $55 eaker radio Fearlessly Crosley led the radio industry to home trial before buying. On such a broad selling policy Crosley has won first place in the industry be- cause buyers found Crosley radio outperformed many far sé More expens- p| ive sets. er T home demon- a pw. stration will ‘ satisfy you 8 tube AC Electric that Crosley SHOWBOX $80 s Genuine neutrodyne 1S a GREAT 3 stages radio am- radio. plification, detector, 2 stages audio (last —_— one being iswo 171 =a push-pull power | | = tubes) and 280 rec- lL | 9 “ tifier. SL 6 tube Battery Operated BAND.- You so much is possible The Bandbor is the ideal radie for places where elec- tric current is not available for AC receivers. This re- ceiver can be con- verted for use from the power lines by means of a suitable power supply unit, 5 tube Dry Cell Operated BAND- BOX, 4 JR., $35, uses 199 tubes with 120 power out- put tube. Ideal set where recharging of storage battery is in convenient. in the Montana, Wyoming, Colorado, New Mex- ico and West, prices slightly higher. Crosley prices do not include tubes. The Crosiey Radio Corporation, Cincinnati, Unio Dept. 18. Please send me literature about your new radio receiver a AC Radio Dynacone TRIAL 1 Name

Say You Saw It In Q S T — It Identifies You and Helps Q S T D N MY HOME nd the new wonderful DYNACONE. Battery Operated Radio Radio 5 DAY FREE

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Ra Ki Solamp As Pioneers in T ELEVISION invite correspondence from in regard to these new theon Products, which are being iccessfully in the Television asting. KINO " AMP for Pri ~ 0. FOTO-CELL for sending—Prices and information upon application RAYTHEON MEG. CO. endall Square Building \4MBRIDGE, MASS. Raytheon foto-@il receiving—List ytheon = ~ - - = - _ 2ower Transformer for 1X 250 Power Tubes or doing the job, not for looks ted at >600 volts plate, 744 volts tifier tube filament. Center taps f the filament windings. Contin- f place windings, 160 M A., con- yofeach7 44 volt winding, 3 Am- put with two UX 281'sfull wave, h sufficient excess for ‘*C*’ Bias. AMERIRAN PF-250 ¢ stin 1033 descrsbing fully the PF-23 Price, each $30.00 ‘ egher West of Rocky Mountains AMERICAN TR ANSFORMER COMPANY slders for more than a8 Years t met St. Newark, N. J. Say You Saw It In Q S T — It Identifies You and Helps Q S T to endeavor to maintain as high a degree of accuracy as can be obtained with the equipment that is available to the Official Frequency Stations. Our Standard Fre. quency Transmissions carry an accuracy of 1/10 of 1% and when one begins to realize the many problems involved in maintaining this accuracy over long periods of time, it is obvious that we cannot expect such precision from the O.F.S. As a result of much discussion, a figure of % of 1% has been decided upon as being a satisfactory compromise between the desirable accuracy and that which can be obtained without involving any considerable expense or work on the part of the operators of Official Fre- quency Stations. Meters that are good to an accuracy of % of 1% and better are available on the market at prices that should be within the reach of the O.F.S. It is possible for the amateur to construct his own instrument and calibrate it from the Standard Fre- quency Transmissions from W9XL and WWYV. It is extremely desirable that fre- quency meters be checked at least once every two months to be sure that their calibration is still within the necessary limits. (Please let us know when you have taken advantage of these transmissions and if you have not already obtained report blanks we would be glad to send you a supply.) Many operators prefer the use of mega- cycles when referring to the various bands. Unfortunately, it is impossible to specify a frequency in megacycles to an accuracy of % of 1% without the use of figures to the right side of a decimal point. That is, unless one is referring to a round number of thou- sands of kilocycles which may be satis- factory for designating bands but which is decidedly unsatisfactory when referring to frequencies within bands. This same thing applies to the use of wavelength in meters. It is possible to refer to any frequency with- in the amateur bands with an accuracy of % of 1% by using a full number of kilo- cycles. This means in practice that all re- ports may be given in figures of four or five digits without the use of a decimal point and still maintain the accuracy demanded of this service. This, then, constitutes an excellent reason for the use of kilocycles when the matter is viewed purely from a point of convenience. This is not the only reason for its use, though. The International Radiotelegraph Conference made the kilocycle its standard unit in allocating all bands and our own Radio Division of the Department of Com- merce has also adopted this standard. Our licenses specify our bands in kilocycles. Al- though the limits are also given in wave- length, this is only an approximate value. In view of these factors, we feel justified in employing the kilocycle for our standard unit and all reports should be given in kilo- cycles. Therefore, in transmissions no commas, periods or other punctuation are Wide ' fro! Atle dep cess any abil The pres Har seri as ft smo of € per: to ; low eith sulz

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‘Aes Ss 2raew ew WS O ‘s t7 {7 i S— Fee ee “We are Depending on your product,” Wide World Photo of the “City of New York." from a painting by Chas. Rosner, N. writes the Radio Engineer of the Byrd Antarctic Expedition N the Antarctic Expedition led by Commander Byrd,—as on his Arctic Expedition and Trans- Atlantic Flight —*PYREX Insulators will again be depended on for unfailing radio insulation. _. AMM These seasoned explorers dare not entrust the suc- PYREX Entering bow! and Stand-off cess of their expedition—and possibly their lives—to Ww. h any equipment which had not proven its complete ee ee ne dl - mah ability to withstand the extreme conditions to be met. power short wave transmitter chown on Their complete confidence in them is ringingly ex- the left pressed by M. P. Hanson, Byrd’s Radio Engineer. 1 “We have every confidence,’’ writes Engineer Hanson, ‘‘that your products will render good service under the extreme conditions to be met, as they have done in the past.”’ PYREX Insulators are not affected by acid fumes, smoke or salt fogs. Their exceptionally low coefficient of expansion r..akes them indifferent to sudden tem- perature changes. Their dielectric strength is from 15 to 35% greater than porcelain. Their power loss is lower than any substance except pure fuzed quartz. For complete technical information and catalogs on either PYREX Power Line or PYREX Radio In- sulators write CORNING GLASS WORKS P Dept.Q-4, Industrial and Laboratory Division CY, New York Office: 501 Fifth Avenue Lower Section of high power short wave transmitter equipped with PYREX *Trade-mark. Reg U.S. Pat. Off. small Lead-in Insulators Say You Saw It In Q S T — It Identifies You and Helps Q 8 T 71

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Potter Condensers QUALI LONG LIFE UNIFORMITY ECONOMY I red for that radio set and power th Potter Condensers. een made by leading manufacturers lo sets, making it safe to follow Ez — ~ Pot ter Interference Eliminator ams no longer need be spoiled by ners, ice machine motors, fans, connect a Potter Interference F ne circuit at the point where inter- ected and enjoy your radio set. ‘Potter Manufacturing Co. North Chicago, IL. a! Organization at Your Service Send For N RADIO Catalog nd Set Builders EW 1929 Cata- ammed full of T, NEWEST, wwn A.C. sets, nets, dynamic PARTS, and accessories ST PRICES. »f radio parts. a REE catalog RADIO MFG. CO., t.,Dept.011 Chicago Radio Say You Saw It In Q S T — It Identifies You and Helps Q S T necessary to break up the group of four or five digits. At the present time there are two factors that are used in converting from kilocycles to meters or vice-versa. The more exact one is 299,820 and the more convenient is 300,000. The more exact value differs from the other by 18 parts in 30,000 or 6/100 of 1%. This inaccuracy is insignificant in view of the % of 1% requirement and the conversion of wavelength-to-frequency is so much more convenient when using 300,000 that once more we can adopt a unit which simplifies calculations without, at the same time, sacrificing anything of importance. We also find that the Radio Division of the Department of Commerce has adopted this factor and that it was used by the Confer- ence. A conversion chart for wavelengths or frequencies between 10 and 30,000 based on this figure has been issued by the Super- intendent of Documents of the Government Printing Office at Washington, D. C., at the request of the Radio Division. Copies of this chart may be obtained at 5 cents each from the Government Printing Office. To assist the O.F.S. in changing over to kilo- cycles, we are having a copy of the chart sent to each one of them with our com- pliments. The chairman of the committee handling Official Frequency Stations is Don C. Wal- lace, W6AM, and if you are already an O.F.S. but feel that you cannot meet the requirements specified above, please notify the Chairman so that your call may be de- leted from the list. If you are not an O.F.S. and feel that you can meet the requirements satisfactorily we would be glad to have your call on the list. Communicate with the Chairman. The chief duties of an O.F.S. are to indicate the frequency of his trans- mission at the end of each transmission, to check the frequency of other transmitters when requested and to aid in the general work of keeping all amateurs within their assigned bands. This is done in the course of their general amateur operation. O.F.S. do not send Standard Frequency Transmis- sions. The following stations are members at this time: W6XAO-W6ZV, W5MN, VES8FC, oz-2AC, W6AM, W1CK, WiIAWW, WS8EQ, W4XE, W5ZAV, W9EGU, W6ZH, W2MU, W4BY, W5SP, W7GQ, W2DS, W1BZQ, W6BGM-W6CVO, W9IG, W1ZL-W1AVW, W2CLA, W8GZ-W8ZG, W9BGK, G2NM, VE9AL, WS8APZ, W50X, W1AAC, WS8BZT, VE38CO, G20D, W6CAE, W9AXQ, W9CPM, W5EW, W1AXA, W9BGH, G2SZ, W6BB, W8DAJ, W9AUG, VE2BE, W2BRB, VE4BT, oa-5BG, W4LK, GI5NJ, W1CCW, W8BAU, W9UZ, W2EF, W6AKW, W6CDY-W6CPX, W6AYC, W6BRO, W6WN, W6BMW, W6CMQ. M casts expe they the « tinct! num Le: minu blade pane minu that |

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The broadcast of the Army-Navy | atone of the big Se - = - ———_—_--— ———» football games. The Big Game Comes Over-- BETTER--CLEARER \ ILLIONS of enthusiastic football fans are It combines remarkable shielding properties» listening this fall to the play by play broad- high electrical conductivity, great strength and casts of America’s greatest games. They are extreme lightness. experiencing almost as keen enjoyment as if they were sitting in the stands. The voice of the announcer comes to them clearly and dis- tinctly because their receiving sets are Alumi- num equipped. Examine the set you contemplate buying. If it is Aluminum equipped you may rest as- sured that the manufacturer has done every- thing in his power to give you the finest pos- sible reception Leading radio manufacturers are using Alu- minum extensively for shielding, for condenser blades and frames, for chasses, sub-panels, front And if you are building a receiving set use Aluminum for finest results. panels and for many other parts—because Alu- We will gladly send you the booklet, “Alumi- minum so ideally meets the varied conditions num For Radio,” which explains the var.ed that radio design presents. radio uses to which Aluminum is adapted. ALUMINUM COMPANY OF AMERICA ALUMINUM IN EVERY COMMERCIAL FORM 2439 Oliver Building Fah Offices in 19 Principal Pittsburgh, Pa. ee American Cities ALUMINUM “The mark of Quality in Radio

Say You Saw It In Q S T — It Identifies You and Helps Q S T

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STATEMENT OF THE OWNERSHIP, MANAGE. MENT, CIRCULATION, ETC., REQUIRED BY THE ACT OF CONGRESS OF AUGUST 24, 1912, Of QST, published monthly at Hartford, Conn., for October 1, 1928. State of eS County of Hartford Before me, a Notary Public in and for the State and county aforesaid, personally appeared K. B. Warner, who, having been duly sworn according to law, deposes and says that he is the business man- ager of QST and that the following is, to the best of his knowledge and belief, a true statement of the ownership, management (and if a daily paper, the circulation), etc., of the aforesaid publication for the date shown in the above caption, required by the Act of August 24, 1912, embodied in section 411, Postal Laws and Regulations, printed on the reverse of this form, to wit: o » « d | ia erent .. 1. That the names and addresses of the publist er, editor, managing editor, and business managers are: Rer designed a new circuit. It is different Publisher, The American Radio Relay League, Inc., and a long step ahead in radio research, Hartford, Conn.; Editor, Kenneth B. Warner, Hart- Let you all about it and why it will out per- ford, Conn.; Managing Editor, F. Cheyney Beekly, forn actory built receiver. Sign and mail the Hartford, Conn.; Business Manager, Kenneth B. coupor We will forward an eight-page, two-color Warner, Hartford, Conn. _ folder 1 set-builders’ bulletin. 2. That the owners are: (Give names and ad- Seen waeawe BBO S22S2S8S22E228262 dresses of the individual owners, or if a corporation, ee . im, Geee & Beebe Mfe. C give its name and the names and addresses of stock- 4 ae & ~. ee meg = holders owning or holding 1 per cent. or more of the pg Bet ny een a ornia. total amount of stock) The American Radio Relay mA} - “dope” oa the “99” League, Inc., an association without capita] stock, in- p : cone fas weal esienel set build corporated under the laws of the State of Connec- ; ieee alleers. ticut, President, Hiram Percy Maxim, Hartford, r Conn,; Vice-President, Chas H. Stewart, St. David's, DN. Sbcnbcdvockseed bia deeuncineeeseeeekbecascas Pa.; Treasurer, A. A. Hebert, Hartford, Conn.; Communications Manager, F. E. Handy, Hartford, Re ee ee Conn, ; Secretary, K. B. Warner, Hartford, Conn. 3. That the known bondholders, mortgagees, and Cit ; State other security holders owning or holding 1 per cent. ree ae ee le or more of total amount of bonds, mortgages, or other securities are: (If there are none, so state.) None, 4. That the two paragraphs next above, giving — . the names of the owners, stockholders, and security holders, if any, contain not only the list of stock- holders and security holders as they appear on the P R ES EN ] ING books of the company but also, in cases where the stockholder or security holder appears upon the books of the company as trustee or in any other fiduciary relation, the name of the person or corporation for The New SRL whom such trustee is acting, is given; also that the said two paragraphs contain statements, embracing Spr adband and Frequency Meter affiant’s full knowledge and belief as to the circum- stances and conditions under which stockholders and security holders who do not appear upon the books of the company as trustees, hold stock and securities in a capacity other than that of a bona fide owner; and this affiant has no reason to believe that any other person, association or corporation has any in- Type terest direct, or indirect in the said stock, bonds, or 108-S other securities than as so stated by him. ” 5. That the average number of copies of each is- sue of this publication, sold or distributed, through the mails or otherwise, to paid subscribers during the six months preceding the date shown above is -tpnntereearecone .. (This information is required from daily publications only.) K. B. WARNER. 10-20-40-80 Meter Bands. Each band Sworn to and subscribed before me this 22d day covers the whole dial and we don't mean of September, 1928. perha Caroline S. Crisman, ; - (My commission expires February, 1931.) Don’t Check Out January Ist. The type 108-S is the solution to your frequency-measuring problem. The low Calls Heard price of $21 is an introductory offer. Or- eGuubtned tess Pace 68) ders will be filled in rotation, Order yours now and save delay. Sgt. Henry P. Karr, Hq. Btry., 2nd F. A. im Du Fell Balletins Out—Write for Them Bn., Camp at Gatun, C. Z LIVE DEALERS WRITE FOR FULL INFORMATION) (20 meters) — sins ieee ‘on laba lafb laga lafd lajd lakm lalb lalm lamp SEATTLE RADIO LABORATORY lapv lasf lasu law laxp laxq lbat lbdq ibe _~ = 33d Av . i lbig 1bkv lbms lbad lbs lIbux lage Ica Icax — oe Ces ledi lejh 1ckp lemp lepl 1da 1de 1du 1dws Idy lex L____ = 1fl 1gd lhv lie lio lje 1lm Imy limr inw Ipd Iqh lqo iIrd iIry 1Isw 1ssz ut lve lvk lvo lvg lvw iwl Say You Saw It In Q S T — It Identifies You and Helps Q ST

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' State K. B. ‘ing to | Man. est of of the r, the or the yy the everse iary for the cing um- and 0ks ties er ; any in- or is- igh the is red A NEW CATALOG JUST OFF THE PRESS Who Buy RADIO/ ’ By making your problems our problems, we know the service you require—and to render you such service the entire Allied organization is dedicated—to give you the service you have a right to expect. Tremendous stocks, remarkable values and a real desire to serve, all combine to make Allied your ideal source of supply. Wholesale HIS big new catalog heralds a new era in radio. Never before have you been offered such variety—such quality—such sterling value in radio as you are now of- fered in this large new catalog. In it, wholesale prices are not a myth—but actual reality. You will marvel that such merchandise, comprising everything that is new and worthwhile in radio can be offered at such prices. Here you will find high quality that is not high priced. If you are interested in radio you cannot afford to be without the Allied Catalog. SET BUILDERS! | RADIO DEALERS! The live radio dealer—the man who keeps pace with the rapid advance of radio will find much of values that are offered in standard kits and parts. real interest in the Allied Catalog. New A-C Sets, Tremendous’ stocks—real organization—prompt D-C Sets, Dynamic and Magnetic Speakers, tele- shipping service all combine to make Allied your | vision equipment, in fact everything that an im- patient radio public is demanding. WHAT ALLIED OFFERS YOU! Allied Service will prove a revelation to you in what radio service can really be. Allied Executives backed by years of training in radio are practical men. They know radio. Their vast experience has built up around them an organization trained to serve. Months of ef- fort have built up here a tremendous reserve of stock that makes for prompt shipments; and this stock is new stock comprising the seasons pick of such prominent manufacturers as Silver-Marshall, Tyrman, Aero, Hammerlund-Roberts, etc. You Profit When You Buy Right Buying right is half the battle. From the small set builder to the large dealer, your success depends upon gauging the public pulse of radio and in buying right. Everything that is new in radio—the items the radio Set Builders, Amateurs and so called “Hams” will delight in the unusual variety—and remarkable ideal source of supply. ELECTRIC SETS public is now demanding are here, ready for your call. Write now—the catalog is free for the asking. beautiful console models. Prices range tures found only in the highest priced Allied offers you a new—complete line Write for Catalog Now from $32.95 to $199.00. Dollar for dol- sets. 711 W. LAKE ST., Dept. P, CHICAGO, ILL. of A-C Receivers, available in either Al : ‘ d R d f lar they stand out as one of the sea- ie © iO chassis form or in a wide variety of son’s leading receivers. Engineered to ex unusual perfection they offer you fea- a © R = RA | © N / Say You Saw It In Q S T — It Identifies You and Helps Q S T

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FROST RADIO FROST-RADIO FROST-RADIO FROST-RADIO FROST- FROST-RADIO New Data Book Now Ready ew Frost-Radio 16 page Data ust off the press, is ready for r. It contains a great deal of information regarding cir- ane technical data on rheo- ariable high resistances, filter ete. We have aimed to a complete authoritative | of interest to every reader of Write for your copy today, in- 10c to cover cost of postage iling. Also contains full in- P f i: 2 Zz 2 gk jon on the new Frost-Radic i d --: i: he ers, this r 1925 HERBERT H. FROST, INC. Main Office and Factory Elkhert, Indiana New York City RE T H. FROST, Ine h La Salle Street, Chiecage return mail your NEW 16-page Data Book g seoves GB ccecces i 4so0ui O1gvil-1s0u) O1avl.is0N) O1ave -is0ud Oravd-isous Olav-.soul o1ava- FROST- RADIO FROST-RADIO FROST-RADIO FROST-RADIO FROST: Neutralization Means— Mor e Power From Any Set proven that neutralization is the only sat hod _of controlling oscillation in a Tun Frequency Circuit and that it increases the actu ywer per stage of amplification 25 to 300 The ?} ne principle can be applied to prac- icall t by the simple installation of X-L Var The result is an amazing increase in the and power of the receiver. Send for r of circuits and picture diagrams f the Variodenser. MODEL oe VARIO-DENSER y, adjustable from 1.8 to 20 micro- -0000018 to .00002 microfarads. Price each $1.00. X-L. RADIO LABORATORIES 1224 Belmont Ave., Chicago, III. Has pacit Dept Nary Transmitung and Receiving Set, 10 watt - er & Transmitter C. W. 1055, 1 SC No. T 1 Bre rophone, 1-1 A Helmet with 194 W. head- se Dynamotor 12-350 volts D. C., 1 CW 1057 & . erphone control box and necessary cables with plug nnectors. Set is equipped with 3 VTl1 tubes und 1 \ allast lamp, outfit for $75.00. Largest stock Radio Transmitting and Receiving material in 1 stamp for our new and latest reduced price list where w —_- CURIOSITY SHOP, 20 South | Philadelphia Say You Saw It In Q S T — It Identifies You and Helps Q S T lwu Ixf lxae lzz 2ag 2aga 2agn 2aic 2ail 2aio 2ang 2anp 2api 2ar 2avz 2ays 2aza 2azu 2bac 2bal 2be 2bg 2bha 2bjr 2bke 2bm 2br 2bvg 2bx 2cgu 2byw 2chk 2ckw 2cx 2fm 2ff 2gp 2jj 2jy 2kx 2md 2mp 2nn 2od 2ow 2pj 2rb 2rs 2rz 2sh 2tp 2uj 2va 2vi 2wl 2xad 2xam 2yi 3ac 3adm 3ads 3aic 3aajh 3aare 3bgg 3cj 3cev Sec 3ez 3gr 3jj 3jm 3ke 3mv 3nz 80n 3qv 3wn 3za 4aba 4acz 4adb 4aer 4am 4apj 4bl 4ea 4ek 4fe 4jr 4rm 4ok 4pd 4st 4uo 5Sabi 5Sacl baeq Saot bSats 5bf BSby 5cl 5gm Sjw 5kg Spt Swe Syd Gago Gah 6aiz 6ajm Galw Gana Gann 6avl Gavp Gazr 6azs 6bhe Gbtx 6bvx 6bzf 6cfj 6csj 6cve 6cxi 6czq Gdev Gdhq 6dj 6dlo 6dom G6dud 6jn Gph Gps Gpw 6rj 6sh 6sk 6xi 6yq 6zde 6zzo Tabg Tago Tawf Tecl 7dd Tfe 7fn 7fs 7mn 7mr Tvu 8adm S8agy S8ajn Sane S8arj Sava Savb 8avx Sawf Saxa 8baz 8bbl Sbbp 8ben 8bfw 8bhz 8bk 8bov 8bqf 8brh 8bz 8caj S8cer 8ced S8cft 8cfr 8cle 8clp 8clt 8emb 8cnj 8cpb 8cpq 8cpx Scug S8cvq 8cyg 8ddn 8de 8dds S8dey Sdpk 8dpo 8drj Sdsp S8dsy 8dtp 8ex 8ez 8fd 8gz 8jj 8mq 8nq 80q 8rd 8re 8ul 8xf Yaas Qafa 9akz 9alz 9Yant 9anz Yaod Yaqi Yas Yaur Yauv Qavv 9asl 9be Sbca Ybed Ybhb Ybhp Y9bjk Yblu Ybkm 9bkz 9bm 9bmw Ybov Ybpx Ybaqv Ybaqy Ybtw Ybyo 9cfm Yemv Yerd Ydbe Ydbm Ydew Ydkq Y9dmb Ydng 9dpb 9dpk 9dps 9dqy Yeap Yecl Yef Yegb Yehn Yein 9emb 9etk 9Yewp 9Yez 9fq 9g] 9h] 9hn Yinz Y9mec Ynv 9oj 9sq 9sx Ysv Yvi eb-4au eb-4cb eb-4rs ed-7Tjo ed- 8zg ee-ear62 ef-8fb ef-8fd ef-8fr ef-Sorm eg-2bm eg-2nh eg-5by eg-bhs eg-ibma eg-5m!l eg-5uw eg-5yq eg-6jk eg-6rb ef-6sa eg-6td eg-G6yq ej-idd ne-3cs ne- 3rg ne-4nv ne-4rn ne-5bby np-4apf oa-2fm oa-2no oa- 5cm oh-6alm oz-4am sa-6avl sb-law sb-lib. (40 meters) laao lah laiu lap laxx lbda libea lIbkp lbux lca led Ichg l1fd lgw lim llp om low Irp lixa 2abe 2agf 2alp 2apd 2atk 2azy 2bav 2bdh 2bt 2cty 2cub 2da 2do 2dx 2gu 2nf 2ng 2ov 2ve 2xaf Saba 3aed S8alq 3ani 8bnu 3bqz 3cfg 3cpg 3fg 3na 3nd Slw 3tc 4aar 4acv 4acz 4ap 4caa 4co 4cw 4dq 4ei 4ng 4nu 4oo 4pt 4qa 4si 4tk 4tu 4wd 4zx Sac b5afx Sahx bage 5aut Save baxi Sayq Sbj bbx Bef Bek 5ql Srv but 5vx bwj Gaah 6ac Gavv 6bec 6Gbhih 6bmw 6bng 6dap 6dl 6dmh 6dmp 6eb 6em 6qb 6ya Takq 7Tbd 7bx Sagv Sagy 8agz S8akx Saul 8baz 8be 8bm 8brf 2cbf Scdb 8cq 8dne 8do S8dqb 8eq 8nf S8ru Yaip Yama Yaok Vapi 9ay 9baf 9bam Ybir 9bjz Ycld Ycy Ydes 9dp Y9du Yehn Q9ud 9ux ea-wy eb-4cb eb-4cc eb-4ft ee-ear28 ef-8dmf ef-8gr ef-Sgrg ef-S8vvd eg-icbh eg-ibma eg-iml eg- 5uw eg-5yk ei-lfp ei-lgn ek-4vf eu-rdw ne-2ea ne- 4cs nn-lnic nq-2cf nq-7cx oa-2rx oa-5bmb oa-5ox sb- lah sb-lao sb-lbq sb-lca sb-lic sb-lid sb-2ad sc-2as su-lna. (80 meters) laaw labz lad laef lafb lait lahv lalb lanh lapl lasd lasu lavk lawk lbbj lbep Ibfz lbi lbjp ibad lbv] lcat lebt leew icdb lefp lemd Icra ldi ldr Ifl lhb lhp lil lin 1ku Imk Ipe Ipi lqb Isl lvb lwq lxv lyb 2aat 2abi 2ad 2afj 2aid 2aif 2aig 2aiz 2alo 2aco 2aww 2ayg 2bcp 2bek 2bex 2bfd 2bfi 2bfp 2bgm 2bh] 2bic 2bif 2bse 2cbp 2cep 2cp 2cpd 2epg 2ctm 2evf 2evh 2cxl 2czr 2dv 2ec Zev 2gp 2gw 2gx 2jx 2mt 2sc 2se 2sb 2wz 2xg 3abi 3ac 3aade 3aadm 3aei Sael 3afw 3agi Sahe 3akp Sale Saob Saqi 3aqh 3ase 8awu 3bgs 3bit 3blp 3bmh 3bns Sbsr 3bst 3bwt 3ca 8cee 3cfg 3cjw 3dew 3jh 3qp Suz 3xs 32f 3zi 32s 4aau 4acd 4af 4bl 4cn 4cs 4ff 4fx 4gl 4ie 4lu 4ay 4rn 4sp 4we 4wg 4xe 5aqd bqa Gaod 6don Saag S8acq 8acz S8ae Sais 8ajk Sakc Sako 8ald Salu Samu 8apb 8arx S8asc Satq Satr Savk 8ayb Sayu 8bem 8bcq 8bez 8bfn Sbgd Sbja 8bnr S8bti Sbts Sbyn S8cfi 8che 8chy 8cjb Scemw S8eng S8ens 8erf S8cye S8dbm 8dbu Sded 8deq S8ded 8dkx S8dme 8dok 8doq 8ds 8ey 8jb 8kr 8mm &8pt 9aaf 9aaj Yahk 9ain 9amu Yapg Yapy 9atv 9baw 9bec B9bdt Ybhe BYbhs Ybwj Y9bwn Y9cmv Sepr 9erm Ycrv 9cuo Ydae Y9dba Ydds 9des Ydgw Yebo Sedo 9egq Yejt Yekw Yeqi Yesn Yhh Yox. W7JC-W7ZZC, 434 Clark Ave., Montana (40-meter band) xem-sfv fe-8jcx fm-8az fm-8as na-7Tto nj-2pa nm-lg nn-lnic no-5fl nz-fr5 oa-2aw oa-2cs oa2gw oa-2he oa-2hm oa-2kb oa-2kj oa-2me oa-2ns oa-2rb oa-2re oa-2rf oa-2rz oa-2sh oa-2xi va-2yi oa3bm oa-3bq oa-3de oa-3jk oa-3jw oa-3ls oa-3me oa-8ml oa3wh oa-2wm oa-3yx oa-4ab oa-4cm va-4lj oa-4nw oa-5pn oa-4wa oa-5by oa-5hge oa-5mb oa-7dx oa-7lj oc-8xz oc-6qh oh-6dws oo-laj oz-2aw oz-2ba oz-2bg oz-2bh oz-4xc sc-2ab. Billings, (20-meter band) eg-5sw oa-2uk oa-2wf oa-2xr k6dqn.

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apl 1fl EVERY TRANSMITTING AMATEUR USES THESE FORMS —a reminder that your supply may be low— —e sees AMERICAN RAOIO RELAY LEAGUE " 9 LOG OF STATION OS — a emcee | exee or | ome ‘cece wemanns a aA Members’ Correspondence Stationery Write your radio letters on League letter-heads—it identifies you with the biggest radio organization in the world, Lithographed on 8% x 11 heavy bond paper. 100 sheets post- paid for 75c or 250 sheets for $1.70. Sold to members only. THE AMERICAN RADIO RELAY LEAGUE ¢ HEADQUARTERS HARTFORD CONN U S&S «a RADIOGRAM Coy OF Oaem SrA hon OF Oem ~veoee es vs) (am 50 Fu) RARTPORD cous i= ae nov a? — TO _BiSS GLaRTS BasBah 257 —— a oe = 3 SUMNER ROaD — —— -- —— ow ee ae ee we eee eee —_ one CAMBR1 DOS Bass - Fee ————— TIS MESSAGE WAS PECE'VED 47 | CONGRATULLTIONS OB TOUR GOOD TRAFFIC EANDLING WORK STOP TOU AED EISS LORBWTSON OMB ABLE [THF DOG SOTS Wale THE BRASS POUNIERS 134608 POR SCHEER GST STOP NORD POET TO «Li (ls atD GLAD TO Gee TEaT TOU ame PUTTING THD CLD EPWENGLAZD DIVIsTOR o> TH MAP STOP LOOK axD °F UT88 DOROTHY © Wek COMMENTOATIONS GEPARTWE? Faow @Tatom | LOCATeD at ; ore ;™= orenarom i | ° arom 1 “7 } | 1asiv/es | 1.180 uote = See anno” roa a Message Delivery Cards Neatest, simplest way to deliver a message to a near-by town. On U.S. stamped postals 2c each. On plain ecards (for Canada, etc.) 1c each post- paid. Seer’ No A.R.R.L. Log Sheets Designed by hams for hams. 8% x 11 bond paper, punched for standard three-ring loose-leaf binder. 125 sheets postpaid for $1.00 or 500 for $3.50. MEMBER'S CORRESPONDENCE a ie A Official A.R.R.L. Message Blanks Most convenient form. Designed by the Communications Department of the A.R.R.L. Well printed on good bond paper. Size 8% x 7%. Put up in pads of 100 sheets. One pad postpaid for 35c or three pads for $1.00. RADIOGRAM A Rade Senctee — ~ wo has at a ot American Radio Relay League 1711 Park Street Hartford, Conn. Say You Saw It In Q S T — It Identifies You and Helps QS T

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Se ee ae od FANSTEEL Balkite Radio Berkey & Gay FANSTEEL PRODUCTS COMPANY, Inc. )RTH CHICAGO, ILLINOIS , i) ee ee > > > > > > > o> 2) > > o> D> MIDGET sienna CODE TELEPLEX SENDER ouLy $Q.50 Guaranteed Postpaid Just like having an ex- pert operator in your home. Be an Good Expert Radio Operator rare, rove This amazing I teaches yeu to read - like an expert in half the e. Repreduces actual sending of expert op- erators. Sends ssages, radiograms, etc. at any speed. Pro- vides practice saywhere,. “anytime. Complete instructions recorded on strong, waxe r rds make everything simple and clear You'll be ama em you hear it send. Just like having an expert opera r home. Why delay when you can get this simple, pract efficient code sender with lessens for enly $3.50; or w requency key and buzzer for $5.50. Satisfac- tion guarantee Money back if not delighted. Send to-day. TELEPLEX CO. 74-76 Cortlandt St., New York, N.Y ROBERT S. KRUSE Consultant for Shortwave Devices 103 Meadowbrook Road, West Hartford, Conn. Telephone Hartford 45327 Say You Saw It In Q S T — It Identifies You and Helps Q S T WiWYV, W. W. Smith, 300 Edgell Road, Framingham Center, Mass. (20-meter band) eb-4bn ef-S8cf ef-dmf ef-8fd ef-gdb ef-S8hip ef-8ix ef-8rrr eg-2bm eg-2kf eg-2nh eg-20d weg-2sc eg-2xv eg-hby eg-5bz eg-bls eg-5ml eg-5ms eg-5qv eg-5vl eg-5wk eg-5byx eg-6ut eg-6vp eg-6yv ei-ldy ek-4vo ek-5yt en-ovn ep-lae oa-2xr oa-3ce oa-3gr oa-5ing ca-7ch oz-2ac oz-2aw oz-2bg oz-4aa sb-law sb-lib sb-2ab ab-2al ab-2ar sc-lah sc-lai ne-Sae ne-8fd ne-8wg nq-2kp wnp. W4GP 1025 Fairmount Ave., Alabama w6adk wé6aie w6aim wé6ajh w6ami wé6aov wéapd w6arv w6ase w6asj w6awy w6bcq w6bi wébir wébmo w6bp w6sb w6ébxi w6ébyz wécah wéccw wé6cee w6cdb w6cdl w6edv w6cj w6cri wéctd wécuk wé6cxd wé6czt w6dbo w6édcv w6édfr w6édfs w6édgq w6édhe w6dhs wédlx w6dnm w6dpf w6édpu w6édwj wé6dzl w6dzs wé6fa wé6io w6oe w6tj w6tn wé6ty w6va w6we w6xbb wé6zan wiaeu wilajh wialk wiTif w7rj wise w7ui wiwb wiwi nj-2pa nm-lg nm-9a nn-cab nn-7nic nq-Zay nq-2iq np-2jt nq-5fe nq-5fl nr-2ea nt-2fp nz-fr5 oa-2kj sa-4ao oa-4ra oa-5he oa-5ht k6alm op-lom oz-laj sb-lay sb-law se-lem se-2ea. Anniston, on Correspondence Department (Continued from Page 78) A Ghost of the Past Glen Avenue, Arlington, P. O., Baltimore, Md. Editor, QST: Last night I happened across an odd file that used to repose on the shelf in the radio shack that nestled under the “old back porch”. My thoughts ran back to those hectic days of “nineteen sixteen” when the non-synec spark crashed its “merry” way over the receptive ether. Perhaps, a few of the “Old Timers” will get a real thrill over something that I found in the box. The “find” bears the stamp of old 3RD at Bancroft Park, Balti- more, Maryland; and the following is self- explanatory. PRESIDENTIAL RELAY, 1916 — For the first time in the history of this grand Republic, the amateurs will demonstrate to the public that they can be relied upon to help the Goverment. We all feel highly honored to be given the chance by President Wilson to demonstrate how well we can pass around this country a message from the white house. .. . PURPOSE OF THE RELAY First, to get you interested in perfect- ing your station. Secondly, as the air will be perectly quiet on the night of this relay, you will have a chance to check up on your receiving outfit. Thirdly, to get a number of good receiving stations that can hear NAA and NAJ, at all times. This list will be turned over to the Government author- ities. Fourthly, to satisfy the curiosity of the President of the United States as to our real worth, and assist the Department of Commerce, all of whom have rendered the amateurs valuable assistance. Fifthly, to give prizes to the most successful ama- teurs. The message will start from station 9XE, in Davenport, Iowa, and will be relayed through the following stations, on the night ee TT

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wg upd mo c2zt dix 6io wi Ziq ay se ee eee SS — lad It IS Good! 38,500 Copies of the Radio Amateur’s Handbook Are Referred to Daily for Guidance and Information Order Now We believe that The Radio Amateur’s Handbook, by F. E. Handy, Communications Man- ager, A.R.R.L. is the most valuable book which any amateur or experimenter could own. Its chapter headings will give an idea of the thoroughness with which the subject is covered. They are “What Is An Amateur?” “Getting Started’, ‘Fundamentals’, “How Radio Signals Are Sent and Received”, “Building a Station—The Receiver’, “‘The Transmitter’, “Power Supply, Keying and Interference Elimination”, “‘Antennas”, ““The Wavemeter—Radio Measurements”, “The A.R.R.L. Communications Department”, “Operating a Station’, ““‘The Experimenter”. These chapters each occupy from ten to forty pages—indicating that each subject is treated in a thorough manner. In addition there is an appendix containing a fund of useful data. Then there is an index, occupying six pages, by which the valuable information contained in the book is made available. This in a particularly important point and has been rompiled and cross-indexed with great care and thought. Altogether the Book contains 256 pages of the most valuable radio information ever found between two covers. The Radio Amateur’s Handbook starts at the beginning and tells what an amateur is, what the League is, what amateur radio is, how to become an amateur, how to learn the code, how to understand what you hear, how to get your licenses, how to build a simple station, how to build a better station, how to operate your station, hew the A.R.R.L. works, how to handle traffic, how to conduct experiments and make measurements, and a multitude of other things too numerous to mention. Anyone who is at all interested in the technical side of radio can ill afford to be without The Radio Amateur’s Handbook. Regular Cover $1.00 Postpaid Anywhere Bound in Leather Cloth $2.00 HARTFORD, CONN. Dear Sirs: copy of the Handbook. Sage eae eee eee eee eee, 3 Say You Saw It In Q S T — It Identifies You and Helps QS T AMERICAN RADIO RELAY LEAGUE, Enclosed find my $------ Please send me postpaid (any where in the world) eoeeeet ee eeeeeseesesesereseeeees

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Short Wave C onverter Unit Complete $99.50 Special Some of the best entertain- is broadcast on the short waves by many power- ful stations. There is no longer any reason why all sl not receive these cxcellent programs from er the world. The Dresner Short Wave Converter Unit is completely assembled. It eff ly covers a wave band of 15 to 550 | meters, and makes reception easily obtainable for fered at the special price of $22.50— com udy to plug into your receiver in a few seconds. If your dealer cannot supply you SEND MON RDER DIRECT and we will ship P.P. prepa UARANTEED. (When ordering unit, be fy whether it is to be used on AC ri DRESNER RADIO MEG. CORP. 644 Son rn Boulevard, Dept, Ql11, New York City — ment of the air | Become an EXPERT RADIO OPERATOR The Quick, Easy W.: The TELEPLEX x yey cope SENDER teaches you at home in half the usual fj time. Entirely elim- inates hit-or-miss methods. Repreduces actual sending of ex- pert operators. Sends you messages, radio- etc.—regular any time, any speed. No experience neces- sary. Tape records carrying complete course of instruc- tions make every- thing simple and clear. Set of 6 rec- ords supplied at no cost. Just what every begin- ner and ad- vanced stu- dent needs for home practice.Used by U. 8. Navy and leading Technical and Telegraph Schools. Write for FREE booklet. TELEPL Fx CO., RL, 76 Cortland St., New York, N. Y. Se ARTZ Ra CRYSTALS n onditt ynally Guaran f your specified a i. meee prices 1 BIB cecoceecescoucecs 5 SD cncescossoseceses 10.00 TRORSTS ccccccccceccocese 15.006 lanks, 2 te 5 mm thick .. 5.00 § y practicable dimensions made to order. Prompt Dellvery 5. T. Rooney. &. Se... 4 Catumet Bidg., Buffalo, N. Y. Ten years crystatiographic experience"’ Say You Saw It In QS T—It Identifies You and Helps QST of the 27th of October at 10:00 P.M., Cen- tral Time. .. . Starting from 9XE on low power, the message will be relayed automatically by Dr. Hall’s famous Re. — Relay at station 9XR. INSTRUCTIONS ~y : yourself quiet until sending sta- wane ave finished. Then, by previous ar- rangements, which you must make, relay this message to all parts of your state. You have until the night of the general election to land this message sapenete but don’t forget the mistakes. PRIZES To the amateur, school, wireless club, or association that delivers the message to Mr. Hughs and gets his recipt for it, we will give a 1-Kw. Thordarson transformer. To the one getting the greatest number of signatures from citizens of the United States, attached to a copy of the message, so that they must read it, we will give a Tubular Audion Panel, mounted and ready for use. Changed Times 1229 Chandler Avenue Evansville, Ind. Editor, QST: Until recently, I considered the dusting of cobwebs from a ham transmitter a huge joke. I have, however, gone through that experience and find it one of the essentials in staging a comeback. A sorrowful surprise unexpectedly await- ed me. Upon getting on the air, I found not the old-time pleasure I once collected from the heap. The conversations seemed mechanical and without the zest of personal feeling. The operators all seem to be rookies instead of the good, steady oper- ators of the past. I began speculating as to the cause of these conditions. Is it possible that it is only I that feel so because I am not as well acquainted on the air as I formerly was? Could it be that short waves have shortened our vocabularies when on the air? Have these waves impaired our op- erating and caused it to be carried on in this nervous manner? Has the spirit of amateur comradeship and codédperation, that medium which made amateur radio, been lost in this maze of high frequency and lower power? If, in the course of time, this letter should take up space in QST, the real ama- teur’s testament, perhaps some amateurs who feel as I do on the subject, would en- dorse my remarks and present their views. —Charles A. Luigs, 9EBW. Rotten Fists 836 Burns Street Forest Hills, Long Island, N. Y. Editor, QST: 1BFX hits a very important point in his letter headed “Help” on page 70 of the July issue.

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XE Lyed Re. sta. slay ate. ral but lub, to ler, ber ted ge, a idy a —— 7I1TROHM Transmitting Grid Leaks and Rheostats now cover the entire line of transmitting tube amateur products are reduced materially. circuits. The prices on these {Your dealer should stock Vitrohm Transmitting Products. ‘If you have difficulty in obtaining them, write us direct. oe PRODUCT RESISTANCE —_—=ODISSIPATION ——CURRENT RATING. _ PRICE 507-2 Grid Leak 5000 ohms 44 watts 90 m.a. 100 watts $2.00 507-3 ~ Grid Leak?* 5000 ohms 200 w atts 200 m.a. 1000 watts 2.80 507-4 Grid I ai akt 50,000 ohms 200 watts 60m.a. 1000 watts 6.50 507-5 Grid Le ei akt 20,000 ohms 200 w. atts 100m.a. —«1000 watts 4.25 507-51 Grid Leak 10,000 ohms 200 watts 135 m. a. ~ 1000 watts 4.00 507-66 Grid Leak** 15,000 ohms = 200 watts_- is 20 n m.a. 1000 watts 6.00 507-63. Rheostatt* | 50ohms 50 watts lamp. _ 5.50 507-59 Rheostat*t | 200hms SQ watts 2amp. - 5.50 507-83 —- Rheostat*t — 12.5ohms _—-60 watts 2.2 amp. 5.50 * Center-tapped + DeForest P or R. ¢ A. 852 De Forest H Tube Steps at 5M—10M—15M for R. C. A. 852 or DeForest P Tube For Primary Control *; Filament and Primary Control Ward Leonard(tectric Company Mount Tube 37-41 South Street Vernon, N. Y. Synchronous Motors for Television In addition to building reliable and satisfactory motor generators, “Esco” has had many years of experience in building electric motors for a great variety of applications. Synchronous motors, small, compact, reliable, self starting are now offered for Television equip- ment. They require no direct current for exci- tation, are quiet running and fully guaranteed. Other types of motors suitable for Television may also be supplied. Write us about your requirements. ELECTRIC SPECIALTY CO. Trade “ESCO” Mark Stamford, Conn 225 South St. Say You Saw It In Q S T — It Identifies You and Helps Q S T

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One of the Most successful Develop- ments of 1928 Amplifiers Built Around UX 250 Tubes are Approved Dongan e with UX 250 Tubes. former for full wave rectification -UX281 tubes to supply B and C to receiver and power for 2UX 250 De 406cnesenseceesaeessesretanens $13.50 529—T former similar to 7568 with the ad- of 2 low voltage windings, one for yes and the other for 227 tubes so mm can build a power amplifier for er radio receiver or phonograph pick- inbheuseeesseesdeeenesesers $16.50 6551—I e Choke, for use with above trans- De sabesasecventeessanseuaneeee $15.00 D-600—Power Amplifier Conaenser Unit ..$16.50 D-307 yndenser Block used in connection DGD siecectnccenscstbeancueeai $10.00 1177 t Power Amplifier Output Trans- . scccsndedansenees s6écccensna $12.00 1176—~ e as 1177 but of Push Pull type $12.00 Custom Set Builders can secure any of these items di- rect from factory at trade discounts. Set Manufacturers are offered the fe coperation of Dongan Engineering depart- meant for their individual requirements. Dongan Electric Manufacturing Co. 2999-3001 Franklin St.. Detroit, Mich. Pou Parts WA TRANSFORMERS of MERIT for FIFTEEN YEARS TELEVISION although still in an experimental stage, has now advanced sufficiently to enable amateurs to build outfits that will give edifying results. Write today for our price list of television apparatus. Photo Electric Devices, Inc. 594 Fiftl Brooklyn, N. Y. Avenue RADIO SCHOOL Earn $35 to $50 Per Week The rapid expansion of RADIO has created many new positions on land and sea. En- roll now New term begins September 10th in both day and evening class. Send for free cat zlogue. MASS. RADIO SCHOOL 18 Boylston Street, Boston Tel. Hancock 8184 Established 1905 Say You Saw It In Q S T — It Identifies You and Helps Q S T It is true that fellows do not try to work some of the new gang. I have cut, myself, at times, and so would any man with any respect for the rest of humanity. I do not mind QSZ, and will repeat as often as a chap wishes. I don’t mind sending at eight or ten per but I sure can’t stand having good Continental murdered the way some of these boys are murdering it today. They are not all newcomers, either. Pos- sibly the chap who can rarely get QSO has such a rotten style or QSC that very few can read him. I tell them and then they get mad, so the only thing to do is to QRT. Personally, I will not answer a sloppy CQ or call and if others felt the same way, things would sound better on the air. Even the commercial operators are getting sloppy of late and I think it is due to ham in- fluence. Could we not have some incentive supplied by the League which would pro- mote better, cleaner operating? Honest, it’s awful. —A. Adair Leonard, “ld at ex 1AYZ— 1ACB—1XAK—WPA—KNU—KFZQ. Alpha Lambda Chi 108 Homer Avenue Buffalo, N. Y. Editor, QST: Much has been said and written con- cerning the nuisance of long continued CQs but with apparently little effect in cor- recting this evil. There seems to be a well- established conviction among many hams that in order to be successful in establish- ing QSO it is necessary to send a long CQ. I have counted as many as sixty. It is evi- dent that I could have answered after the first three. QST suggests nine, which ought to be adequate. It is my opinion that long CQs are only answered to get the nuisance off the air. At the recent Atlantic Division Conven- tion, I observed great activity in initiat- ing delegates into various “Greek letter fraternities”. As far as I could ascer- tain, the chief activity of these societies is the initiation. Now, why not add one more and make it a universal one. Call it the Alpha Lambda Chi (meaning “Against Long Calls”) and hold an initiation at each con- vention, the qualifications being only two, viz., (1) Promise not to send long CQs, (2) Promise not to answer long CQs. I believe that if more of us would ignore long CQs, the practice would soon become obsolete. —Burton C. Simpson, 8CPC. GBA 117 North Sixth Street La Crosse, Wisc. Editor, QST: As a suggestion as to why so many of the QSL cards sent out never receive a reply to the sender in the form of a re- “hy We comp) count prices to shi detail Quart 80 mi

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NZ, loss and high overload. furnace alloys of non-oxidizing nature. Jewell instruments have zero adjusters. log No. 15-C. Write for a copy. “28 YEARS MAKING Still the Standard Jewell thermo couple ammeters for high frequency work are still the standard of the amateur fraternity for making current measurements at radio frequency, for they completely fulfill the requirements of accuracy, low The thermo couples of these ammeters, which are available in various ranges, are made from special electric A guaranteed overload capacity of 50% is an indication of their rug- gedness. The loss in the instrument is held to less than one half of the minimum required by the Navy. The Pattern No. 64 high frequency ammeter has a three inch, black enameled case. Scales are silvered with black characters and movement parts are silver plated. All Jewell radio frequency ammeters are described and listed in Radio Instrument Cata- | Jewell Electrical Instrument Co. | 1650 Walnut St., Chicago, Ill. oar CO me ae panto FREQUEN d 2 Pattern No. 64 Radio Frequency Ammeter GOoOopD INSTRUMENTS” New Transmitting Tubes We expect to have available in a short time the most complete line of transmitting tubes ever sold in this country. Output ratings from 5 to 1000 watts, with prices far below tubes now offered. Particularly adapted to short wave use. If interested, send your name for full details when ready to release. Quartz Crystals, guaranteed. 160 meter band, $10.00; 80 meters $17.50; 40 meters $25.00. Public Address Equipment Starting with our well known and widely used Two Button Broadcast Type Microphone at only $40.00, we can supply any equipment for public address work and similar uses. T3020 Microphone Transformer, $10.00. “Trumpet” Horns. as used in Public Address Equipment, complete with unit, $25.00. E. F. JOHNSON COMPANY, Waseca, Minn. RADIO IN BRASIL When in Brasil, apply to M. BARROS & CIA for anything you need in connection with radio. M. BARROS & CIA 70 sob. Rua S. José 70 sob. Postal Box 89 Rio de Janeiro Telegraph address, Radioparte, Rio de Janeiro Branch: Avenida S. Joao 4, S. Paulo, Brasil Say You Saw It In Q S T — It Identifies You and Helps QS T The Best That _Money Can Buy goes into Har-field Resistors. Best both in brains and materials. That’s why Har-Field Resistors are so uniformly accurate —why they bear our unqualified guarantee for one year— why more and more of the leading manu- facturers are buying them in large quantities for use with their own apparatus. A few of the more prominent we list below: Stromberg-Carison Tel. Mfg. Company Kolster Radio Corporation Splitdorf Electric Co. American Transformer Co. ae ee Fansteel Products Co . , —~ Samson Electric Co. Zenith Radio Company Philadelphia Electric Storage Crosley Radie Corporation Battery Company Western Union Telegraph Co. A. H. Grebe & Company Tell us about the resistor you want. If we can’t sup- ply you from our standard range of sizes, we shall be glad to make up samples for you with prices. Write to HARDWICK, FIELD, INC. SALES OFFICE HAR-FI EL FACTORY 100 Fifth Avenue | 215 Emmet St. New York WIRE-WOUND Newark, Wi. J. RESISTORS ea a a A 83

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7 lelevision Simplified~

Controlling the receiver scan- ning disk—that’s the big problem in television. Yet there is nothing to it when you have the SPEED CON- TROL CLAROSTAT. You can bring the scanning disk to speed and hold the image en the screen as easily as you steer your car down the center of the road. A Handsome and Useful Device SPEED CONTROL CL AT

v. pat. OF able speed motor of 1/8 hp. istill to practically full speed in f knot Pushbutton for quick starts and for tion. Heavy metal case. Properly venti- a ew terminals. 25 to 500 ohm resist- ) watt rating. Readily mounted. Convenient And it for $5.00. I 1at’s only half the story. The SPEED INTROL CLAROSTA T has no erid of applica- tior electrical work where a variable or tance is requir WRI r e regarding the SPEED CONTROL CLAROSTAT well as other Clarostats for every radio purt T send a quarter for ‘““The Gateway to Bett the best investment you ever made in CLAROSTAT MFG. CO., Inc Specialists in Variable Resistors 283 North 6th St., Brooklyn, N. Y.

DODGE RADIO SHORTKUT Ww Appendix an id Re: s for Better Key Work. Fixes Signals nd to -Kills Hesitation, Cultivates Speed and Good ‘ Prodt es Results. Slow Hams raise speed to 2 r in few evenings. Previous Failures qualify and pass exe juickly ‘Be ginners master code and pass in ten L}

IDGE HIGH SPEED METHOD ensive Speed Practice) Q < ¢ r Hams in 35-40 per class. Five Hams made this gain in few evenings. One of ther y tes total practice only. DODGE MORSE SHORTKUT E l by Radio Ops—Kills tendency to mixup

or Either code used as desired. REPORTS FROM USERS Tel ete story—Mailed on request. Radio $3.50 eed $2.50. Morse $2.50. Money order None Foreign add 50 cents. See our Hamad Cc. K. DODGE, MAMARONECK, NEW YORK.

w Hook-ups. This ne shows how to nake Short Wave Re- eiversand Short Wave Adapters. How to use the new screen grid . — be in D. C. and A. C. ‘ans ircuits. How to build for it: Power Amplifiers, and ABC Eliminators. Up to the minute nformation on all new radio develop- ents. Set | eens Fans, Dealers, end for it tod KARAS ELECTRIC COMPANY 4030L1-N. Rockwell St., Chicago, Ill. Please send me your "free book

ee bebe tit |

Say You Saw It In Q S T — It Identifies You and Helps Q S T turn card, will say that I still get cards reporting my signals and addressed to calls which I have not had for several years. If the gang would spend four bits for a new call book, they would save that much in lost cards and postage. Very truly yours, —Edwin L. Benton. Information Montrose, Iowa. Editor, QST: For some time you have been telling about the help the beginner is getting from the old timer. They should, no doubt, re- ceive this assistance but there is'one phase of the subject that has not been given enough atteption. Since you published my report on 20- meter work in the April issue of QST, I have been getting letters from beginners asking all sorts of questions. First of all, most of them imagine there is some big “hocus pocus Indian Medicine Man” stuff that we say to a set to make the wave do its stuff. The only time that I ever said anything was when a tube blew. In the second place, they don’t even tell you what they want to know. Several have said that they had built low power trans- mitters that didn’t work the way they should and, “What’s the matter?” How can any answer be made to that question? If they don’t ask any specific questions, they should, at least, enclose a complete dia- gram of the set giving constants. Last, but not least, a whole lot of them sealed the letter and forgot to enclose a two cent stamp. To be sure, they ran after the postman but couldn’t catch him. In most stations, correspondence is a big item of ex- pense and if we must pay postage as part of the accommodation of answering questions, there will be fewer tubes bought. The questioner should bear his share of it. To work 20-meters or any other wave, the chief things necessary are a steady note and a good radiating system. This is old stuff. QST has been preaching it for years, but it seems that lots of fellows have missed it or else, were in such a hurry while read- ing it that they don’t know what its all about. Please don’t take it from this that I don’t like to help a beginner. I sure do. How- ever, I don’t want to answer fool questions like, “Can I work so-and-so on 20-meters with my set?” And then, tell me nothing about the set. Neither will I pay the postage or read their minds! —Bob Heine, 9AWB This applies to a still greater extent in the handling of the Information Service at Headquarters.—A.T.E.

aom= = ®

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wa. ing om re- ven 1S- Now! Sangamo Transformers at a new low price. And push- pull transformers to match new power tubes and dynamic loud speakers. A small expenditure and you can have one of these modern amplifiers with plenty of capacity to handle the low notes. Nothing equals the full toned beauty of an amplifier built according to the diagram shown at right. | Write for descriptive circulars. SANGAMO ELECTRIC CO. Springfield, Illinois Build this modern amplifier at low cost! SANGAMO HIGH QUALITY AUDIO AMPLIFIER amgame ty Guaranteed—Mounted—Complete 250 watt 550—700 each side ; 700 watt 1000—1500 each side 700 watt 2000 — 2500 each side a Also Polyphase and 25-cycle Transformers Add $2.00 for fil. winding 9CES F. GREBEN 1927 So. Peoria Street, Pilsen Sta., TRANSFORMERS Chicago, Nionis Elections, football games, big National events will boost radio business this year. Set build- ers willreap a rich harvest, SBarawik service wil make you money. Everything in A-C sets, short wave, om, parts, supplies orid’s largest radio Stocks on hand. Orders shipped same day, Lowest rock-bottom wholesale prices Write for Free Radio Catalog BARAWIK CO. iit2A Sana! sta. 7 CHICAGO, U. §. A. laboratories, accepted standard. standard are clways in stock. Write for information and prices PACENT DUO-LATERAL COILS OR experimenters, engineers and for special circuits, Pacent Duo-Lateral Coils are the A complete line of all | turn ratios PacentElectric Co., loc. 91 SeventhAvenue, New York You Saw It In Q S T — It Identifies You and Helps Q S$ T Ld The finest receiver can be improved with Tele- vocal Quality Tubes. All standard types. Ask for them at your deal- ers. TELEVOCAL CORPORATION Televocal Building Dept. R-5, 588 12th Street West New York, N. J. aS La» fe aw,

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The Art of Tuning Is More Than Just Turning a Dial Mere reception of a radio signal is notenough. It has ceased to be, “How many stations did you get?” The thing of importance to- day is, “How well did you get them ?” There are two major operations in tuning a set: ont fe locating the sta- Standard «t10On—and modu- Modu Plug lating it so as to &2.50 obtain the best quality of tone. The ‘ ralab Modu Plug is the perfect volume and nm n control. With it, all the true beauty of tor naturalness of speech reproduction can It | to any set in a moment without addi- tional v g or complicated connections. Equally as adapt » for volume control on phonograph pick-ups and sp. rs remote from the set. An ir ting book full of picture and wiring dia- gram ving the use of Centralab Volume Controls and R s yours for the asking. CENTRAL RADIO LABORATORIES Centxalab 18 Keefe Avenue Milwaukee, Wis. Off the Press September 1 “RADIO THEORY and OPERATING” Mary Texanna Loomis Lect radio, Loomis Radio College; Member tute of Radio Engineers. 992 pa illustrations. right r date; Thoroughly revised ; contains new “Q” signals and laws and r ations for 1929. Used by hundreds of colleges | Government radio schools. Sale by bookdealer r sent, postage paid, on receipt of $3.50 che r money order, LOOMIS PUBLISHING CO., Dept 5, Washington, D. C. BECOME A RADIO OPERATOR See the World. Earn a Good Income. Duties Light and Fascinating. LEARNIN THE SECONDPORT U.S.A. Radio I » located here. New Orleans supplies opera- sus Gulf ports. Most legical location in me to for training. Nearly % of radio operators graduating on the Gulf during the past six years trained by Mr. Clemmons. Instruction. Member of the ARRBRL—Call “5 G RB” Day end Night Classes—Barell anytime—Write fer cir- GULF RADIO SCHOOL New Orieans, La. 844 Heward Ave. Say You Saw It In Q S T — It Identifies You and Helps Q S T A New Condenser IE amateur will have to keep on his } toes if he is to keep up with the fast-growing crop of new equipment which is appearing on the market to meet his needs in the new year. Changed fre- quency bands, more limited territory and the consequent need for a higher standard of performance is to result in the produc- tion of much new apparatus designed to fulfill the more stringent requirements, Falling in this category, the new variable condensers of the Radio Engineering Lab- oratories are worthy of study. Departing from normal practice the condensers are fitted with a rugged die cast “Y” shaped end plate in which is mounted the double conical bearing. An unusual and commendable feature of this bearing is that the shaft runs in a pool of mercury and so is free from the electrically noisy contact which has been such a bug-bear in tuning elements. Several types of condenser are provided, each with this end plate assembly as a foundation. In one of these, which is fitted with a single stator and single rotor plate, the capacity range is made adjustable by provision for the movement longitudinally of the stator plate. In a second type the capacity range can be varied by adjust- ment of a lumped adjustable capacity built into the condenser. In all of the models the plates are of heavy brass, the construction, in general, being splendidly substantial. HIGH RESISTANCE Pai

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r1 OMSK Ae sees FLECHTHEIM SUPERIOR CONDENSERS A COMPLETE LINE OF HIGH GRADE TRANSMITTING CONDENSERS List Prices TRANSMITTING | | 7 Type T, for Type TH, for Type HP, for CONDENSER 3 1500 V DC 2000 V DC 3000 V. DC 1 Mfd. $ 4.50 1 Mfd. $ 8.75 1 Mfd. $20.00 2 Mfd. $ 8.50 2 Mfd. $13.50 2 Mfd. $32.50 4 Mfd. $14.50 4 Mfd. $22.00 4 Mfd. $60.00 PLATE BLOCKING AND GRID CONDENSERS Type T200 For 2000 V DC For 1500 V. D. C. .00025—$3.00; .001—$3.25; .002—$3.50 A More Effective and Dependable Condenser FOR LESS MONEY That’s the unanimous opinion of “hams” everywhere. They stood up for W2APD —the amateur who handled traffic froin storm-swept and devastated PORTO RICO. (W2APD was personally commended for his excellent work by the U.S. Navy) and, there are W2ALU and W2KR, the amateur stations that are handling a large amount of the traffic from the BYRD EXPEDITION—WFBT. OF COURSE, THESE FELLOWS USE FLECHTHEIM! YOU, TOO, SHOULD USZ THEM. (sig) 73’s W2afs, Chief Engineer Write for New Catalog X A. M. FLECHTHEIM & CO., Inc., 136 Liberty St., New York City, Dept. QT IT HURTS To back off your coupling and lose 15%. It cuts even deeper to detune for a total loss of 30%. What’ll I do??? Put in a mercury arc and raise your output an easy 30%— same radiation as before—and a 1929 note. Ask 3PF, 5APO, 9DLD, 9BSS, 9EGU, 8CKC, 8DBQ, 1DL, 9PU. Follow the gang, and your rectifier problems are solved. RECTIFIER ENGINEERING SERVICE 4837 ROCKWOOD RD. RADIO 8ML CLEVELAND, OHIO co) UNI-RECTRON POWER AMPLIFIER (9 (IDEAL FOR USE WITH DYNAMIC SPEAKERS) As the Uni-Rectron stands it is MODEL AP-935 whisper to the loudest crash of a super power amplifier, which sound—R.C.A. Uni-Rectron am- can be used in connection with plifies each note at its true any radio set and loud speaker. value. High and low notes are Binding posts are provided for all treated alike. input to the Uni-Rectron and : output to the speaker. Requires ati te ae deliv. no batteries for its operation. It . obtains its power from the 110 Also by removing the input Volt, 60 Cycle alternating cur- and output transformers it can rent lighting circuit of your he used as a source of power for an oscillating or transmitting house. a | LIST PRICE $88.50 tube, furnishing power for all The UX-210 r power am- circuits, grid, plate and filament r ~ (without tubes) and is the cheapest form of plifying tube and the UX-216B or 281 rectifying tube are used S .75 Power Supply for Amateur with this amplifier, which can- pecia EA. fa gy purposes ever of- not overload. From the faintest New. AMERICAN SALES CO. 19-21 Warren St., New York City Say You Saw It In Q S T — It Identifies You and Helps Q S T

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k A, Age Ant ote Marita ct rare © comically export dependable A ’ receiting and trangmiting’ — <s? rudie apparatus: é re “a . t om © ay 7 a 4 ord “ee 7

By A We You si capped Would 3 and fo method positive MORE AC‘t your tr who ha tors. Wr THE 6343 S. Ke ARE YOU HANDICAPPED ak Arm or Other Weakness? t be a FIRST-CLASS operator handi- ak arm. This is the SPEED age. yourself in the hands of an expert asy instructions if you thought his remove your handicap? If you knew s system would make you a FASTER, RATE operator? Then write CANDLER nd get from him the advice of a man ed many of the world’s fastest opera- ~! No obligation. CANDLER SYSTEM CO. Dept. AR Ave. Chicago, Ill. dzie

| Amateur | Radio | 508 So. De

= ALWAYS

UP-TO-DATE | Issued quarterly,March, June, September and December. Single copies U.S. and Canada $1.00 (Foreign $1.10.) Yearly | subcription $3.25 (Foreign | $3.50.) ind Commercial Stations from 83 | different countries. AmateurCall Book | | arborn St., Chicago, Ill., U.S.A.

88

WHY NOT SERIES GENERATORS R. William O’Neill of Downers Grove, Ill., suggests that plate sup- ply generators would give a better output from the tube transmitter standpoint if built so that at least a part of the field winding was in series with the armature so that it could act as a filter choke. Since the ordinary shunt generator has no series winding at all but is con- nected as shown in Fig. 1 it is necessary to use a freakish circuit to take advantage of 0: | SET eae wat | 3 Ordinary Shunt Wound Generator FIG! the idea. In Fig. 2 the field has been put in series with the load and as this would mean that there is no field whenever the load is off an extra load R has been con- nected in parallel with the regular load. When the key is up and the load discon- nected this extra load provides enough cur- rent so the machine voltage does not dis-

appear. The trouble with these schemes is of course that the machine voltage ;, —— loan) Steep aie Field $ SET R Es

Changed to Serres FIG.2 changes when the load goes off and on. Therefore the final arrangement is that of Fig. 3 in which the key connects the load R to the circuit whenever the set is not

| om | Dummy | SE? a) : Changed to Series with a dummy load on back contact of key FIG. 3

connected. The load R should of course draw about the same current as the set. The scheme was tried on a %-kilowatt 1000- volt Western Elec. machine running at 2250 r.p.m. This machine had a slot ripple of 712 cycles and a weak commutator ripple of 3562 cycles. When connected as shown the ripple was almost completely re- moved with no filter but a 1 microfarad condenser. The real way out would appear to be to design machines compound instead of shunt when they are to be used for telegraphing which is a service quite different from broadcast work. Say You Saw It In Q S T — It Identifies You and Helps Q S T TRANSMITTING HINTS

25 50 100 has har you cat Als Sets issu stru

||

i

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or =r". Pilot Precision Parts for SUCCESSFUL SHORT WAVE SETS Made in the World’s Largest Radio Parts Plant 15 m4 Max. RDINARILY you don’t consider price when you buy parts for 25 Mmf. Max. short wave sets, but when you discover the low cost of PILOT 50 Mmf. Max 100 Mmf. Max. PRECISION PARTS, and then consider that all A.R.R.L. traffic at the New York Radio Show was handled on an all-PILOT receivers, that Byrd’s experts built their airplane sets around PILOT coils, that Ft. Wood has chosen an all-PILOT S. W. Set, in preference to the many other types, for handling Army traffic -- Then : you realize that you better send Pilot Electric Mfg Co Inc 4c in stamps for the PILOT poser = mg sd 4 e catalogue listing 200 parts. 322-Q Berry Street, Brooklyn, N. Y. NEWEST S. W. SETS RADIO DESIGN QUARTERLY, edited by M. B. Sleeper, contains exclusive articles by R. S. Kruse and other S. W. experts. Also articles on shield grid sets, A. C. Sets, airplane radio. Send 25c. for four issues—over 200 pages of the finest con- struction articles. Send stamps or coin. | . Red Ring Orange Ring Yellow Ring Green Ring Blue Ring 25c.--200 PAGES 17-30M. 30-52M. 45-105M. 93-203M. 200-500M —— LAST MINUTE SPECIALS JEWELL—high resistance voltmeters o-2.50V. D.C. (3 readings) list $22 ......... Our Price $4.75 ea. Genuine Black Bakelite Panels 38” x 48” 8/16” thick, Reg. Price $29.00 .......... - 8.75 “* U. S. ARMY Aeroplane Spark Transmitters, Gov. cost $47 each ............eeeeeee- " 4.75 “ G Ee, Seeeerem HISURG Tees ClO TPE) ccc vc ccccccccccccececsccscccccoses ‘i La * Eby A.C. Adapter Harness with Volume Control. For 6 tube Sets, list $10.00 ...... - 5.00 “ Gould Kathanode Unipower, Automatic Radio “A” Power (6 volt), list $39.50 ...... a 13.75 * AMERICAN SALES CO., 19-21 WARREN ST., NEW YORK CITY Barawik, the first and oldest radio specialty condensers that are house, offers you unusual service this year. ; Built Better — to endure. eifes’ Deal with an old established, reliable Write for The Resear bonee. ere a eee honest iS er ere cos {ssn sricenom aoa: Barta, hort wateuctrs 68 Washington Street f BARAWIK CO. chicago. U. a QS T OSCILLATING CRYSTALS NOTICE—New Prices Effective November Ist, 1928 AMATEUR BANDS. Prices for grinding crystals for use in the various amateur bands are as follows 1715 to 3000 Kilo-cpcle band....... cccccccccccccccccce soccccces --» $20.00 S508 to 4000 Eiilo-cycle Dam... cccccccccccccccccccccccccccccccccceces $27.50. 7000 to 7300 Kilo-cycle band............+-- eSCocesenencsecesceseses $45.00 The above prices are for grinding a crystal at a random frequency, said crystal to be of the FOWER type. and its quency will be stated accurate to better than a tenth of 1% All crystals are absolutely guaranteed, and immediate leliveries. Add $10.00 to the above prices if crystal is to be mounted in our POWER type of Holder. BROADCAST BANDS. We desire to announce that we can make prompt delivery on crystals ground to your assigned frequency accurate to ILUS OR MINUS 500 CYCLES for $45.00 Unmounted or $55.00 Mounted. In ordering please mention plate voltage and type of tube used These crystals are absolutely guaranteed We are at your service to grind for you, crystals other than mentioned above. We will be glad to quote prices for*your particular requirement. Crystals ground to any frequency between 40 and 10,000 Kilo-cycles. SCIENTIFIC RADIO SERVICE The Crystals Specialists P.O. Box 86, Dept. ZC, Mt. Rainier, Md. Say You Saw It In Q S T — It Identifies You and Helps Q S T

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“CHI-RAD” Complete Stock of Leach Relays R. E. L. Products 3000 Volt Rectobulbs Omnigraphs Vibroplexes Silver-Marshall—Shield-Grid Short Wave Receiver Send for New 1929 Ham Book---FREE! CHICAGO RADIO APPARATUS CO. 415 S. Dearborn St., Chicago RADIO OPERATORS WANTED THE EASTERN RADIO INSTITUTE can train you quickly and thoroughly because: MODERN AND EFFICIENT METHODS THOROUGH INSTRUCTION under staff of LICENSED COMMERCIAL OPERATORS MODERN APPARATUS including SHORT WAVE TRANSMITTER FIFTEEN years a RADIO SCHOOL THE OLDEST, LARGEST and MOST SUCCESSFUL schoo! in New England. RECOMMENDED BY THE A. R. BR. L. Day or Evening Classes Start Every Monday. SPECIAL CODE CLASSES e for Illustrated Prospectus EASTERN RADIO INSTITUTE 899 BOYLSTON STREET BOSTON, MASS. World’s Standard Precision Parts In Karas Short Wave Receiver Enjoy the s of hearing stations thousands of miles away Karas engineers have developed short wave equip- ment to highest point. Easy to build. Easy to tune with Karas Micrometric dials. 63 to 1 ratio. Uses Karas con- densers bui ke a fine watch. Karas coils and sudios— standard e world Send to-day for cemplete infor- mation ar mstruction blue print. Free. KARAS ELECTRIC COMPANY 4030L2 N. Rockwell Street, Chicago ee “SS SF FSB SF BB eB eee ee eee ee BED ccccccccccoceenceseeseeeoosoeeseueceennseeeeeeuase Bt. ANd NO. .nnceccceccccccccccccccvccccccssscccccseses GE GRE Bete cccccccncccccecccesssecececcceseseesescse 4030L2 Say You Saw It In Q S T — It Identifies You and Helps QS T THE USEFUL MAZDA LAMP Mr. F. A. Lidbury of Niagara Falls con- tributes an idea that most of us should have thought of but did not. It is given’ here- with. “Though the idea is an obvious one, I have never seen a note on the usefulness of the ordinary incandescent lamp as a pro- tective resistance in the vlate supply of transmitting tubes. In adjusting my 50- watt power amplifier recently, I found a bank of these things invaluable. I have 8-125 volt, 50-watt Mazdas mounted in series on a strip of hard rubber in my 1000-volt plate supply. On a short circuit or its equivalent these limit the current to 400 m.a.; on the other hand, with a nor- mal drain of 100 m.a. the voltage drop over the bank of Mazdas is only about 60; and this 6% loss is low pay for the protection obtained. Of course a short circuiting switch, after adjustment, will get rid of this loss, but I prefer to take it myself on account of the protection obtained should anything unexpected happen in the course of operation. It is not generally realized type would be better for this purpose on when lightly loaded. If it were, I am cer- tain that this very simple device would be more used. Below are tabulated some very rough measurements of the present com- mon form of 50 watt lamp. Column 1 gives the current in milliamperes; column 2 the voltage drop per lamp, and column 3 the voltage drop over the bank of eight lamps described above. This will be sufficient I think, to give an indication of what they will do. The lamps in question are, I be- lieve, gas filled, and the older evacuated type would be bettter for this purpose on account of the possibility of internal arcing over in case of a filament breakage; but I didn’t happen to have any handy at the time, and one usually has to order them specially now. I don’t think there would be any essential difference in the use, though the resistance curves are probably different somewhat. Mazda Type A 50 Watt 125 Volt CURRENT VOLTS VOLT DROP OF 8 IN M. A. PER LAMP LAMPS IN SERIES 50 1.4 11 100 8 64 150 19 152 200 33 264 250 51 408 300 74 592 350 100 800 400 125 1000 I am sending this to you because I found it is useful myself; of course smaller and fewer lamps would be used for a 210, larger and more (or higher voltage lamps) for a 204. I daresay this has been suggested time and time again; but I haven’t happened to see it, and I daresay a lot of other fellows haven’t. I am told that the vacuum type is what is sold as “rough service”. I be- lieve these were actually the ones referred to above.” + vy Se, 4 wanes MSGR cy