QST 1920-10: Vol 4 Iss 3

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—_—_—$————<————— i. OCTOBER 1920

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NG RADIO SEASON WILL BE ESPECIALLY INTERESTING D INCREASE IN THE NUMBER OF CONTINUOUS WAVE : LLED BY HUNDREDS OF AMATEURS THROUGHOUT THE FLEXIBILITY OF A “C-W” TRANSMITTER—USED AS A ER-MODULATOR, OR “C-W’’—TOGETHER WITH THE EX NSMITTING RANGE AVAILABLE, BIDS FAIR TO REVOLLU- a LE AMATEUR RADIO FIELD OUS OF KEEPING IN PACE WITH RADIO PROGRESS YOU TED IN HIGH GRADE CONTINUOUS WAVE EQUIPMENT! nit Drive motor of induction type operati yn 110 volt, ge Current Compound wound D.C. Generator, 48 Commutator Volts, 175-200 Watts, continuous. Set mounted on substantial shed complete with Field Rheostat regulating output voltage Price: F.O.B. Boston, $130.00 175-200 Watts Delivery: Oct. 1, 1920. Price: $70.00 == Volts, 60 Cycle, Alternating Current Rated at 4% HP., but op % H.P. continuously. Draws 4.5. Amperes, 1750 R.P.M Price: $27.50 ' ee OTe TT eT ee Cee ee suaee oa | M PRE 6 ois nn nc a Od ce de wae HRA $7.00 ‘ tance —Type 182 rect for Electro magnetic Circuit. Range: 200-325 M........... $10.00 Sse ¥ tance Type 181 ect for Colpitts Capacity Feed Back Circuit. Range: 200-325 M.. .$7.50 C.W tance—Type 183 t for Grid Tickler Feed Back. Range: 200-325 M..... ' . .$12.50 I e 170. Consists of two 1 Mfd. Condensers and two iron core = mounted in box with hard rubber panel. Guaranteed for heniias 25. Ga, awa take swan enue . iaind ot ave es i $16.00 WILL BE PLEASED TO SUPPLY ANY INFORMATION ONCERNING “C-W” WHICH YOU MAY REQUIRE mn 14”°—108 pages—over 100 illustrations—sent upon receipt of ten cents. \ Rebate Certificate good for 10 cents on first dollar order is inclosed.

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: MANHATTAN ELECTRICAL SUPPLY CO., Inc. New York, Chicags ca CLP. Te a aT ee ; TUSKA *“C.W.” INDUCTANCES TUSKA C.W. INDUCTANCE—tType 182. This inductance is designed for the electro- | Topo] .| magnetic circuit shown. The aerial eee Tr j and filament connections are variable by means of a positive contact switch lever. The winding is threaded in Bakelite tube 334.” in diameter by 744” high. Bakelite panel 43%,” x74”. Wave — range 200 to 325 meters. Shipping weight 2 lbs. Price . - $10.00 ‘pe TUSKA C.W. INDUCTANCE—tType 181. The correct coil for the capacity feed-back a te=7-™: | circuit. We recommend this circuit A ~ . . — . e *' J] | strongly; simple and effective. The in- Bay ————~ ductance has one winding, two switches, and four binding posts. Our design makes it easy to operate. Bakelite tube 334” by 6” high. Bake- lite panel 3144”x6”. Wave length range 200 to 325 meters. Shipping weight 2 Ibs. Price - - $7.50 TUSKA C.W. INDUCTANCE—Type 183. Some __. experimenters prefer the grid tickler Ey 35 | type of feedback. Our inductance | Type 183 is designed for this kind of circuit. The grid coil is wound on a small Bakelite form which rotates inside the plate coil. A knob on the panel controls the coupling between grid and plate. Tube size 334” x 74” Panel 434,” x74”. Wave length range, 200 to 325 meters. Shipping weight 2 lbs. a Licensed under Armstrong lt S. Patent No 1,113,149. “October 6, 1914 "end pending U. S. Patent Applic ation, Serial No. 807,388. Your Dealer will have TUSKA “C.W.” EQUIPMENT: inestock::” If he hasn’t, send us his name, and we will mail you our booklet on C.W. THE C. D. TUSKA CO., HARTFORD, CONN. These Dealers Carry TUSKA “iW,” ACCESSORIES. Im Stock.’ ATLANTIC RADIO COMPANY, Inc,, 88 Broad St., Boston, Mass. GEO. S. SAUNDERS & COMPANY, ‘44 Devonshire a Boston, Mass. PHILADELPHIA SCHOOL OF" WIRELESS TELEGRAPHY, Parkway Bldg. Broad and Cherry Sts., Philadelphia, Pa. DOUBLEDAY-HILL ELECTRIC COMPANY, 719 Liberty Aye., Pittsburgh, Pa, A. H. CORWIN @ COMPANY, 4°West Park St., Newark, N. J. AMERICAN ELECTRO TECHNICAL APPLIANCE COMPANY, , Aw 1, 235 Fulten, St,, N No¥ GONTINEN FAL RADIG AND ELECTRIC CORP., 6 Warren St, New was Del ALWAYS MENTION'O'$ T°WHEN' WRITING ‘TO ‘ADVERTISERS

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WHICH DO YOU WANT? A Large Wavelength Range with Greatly Impaired Efficiency A Moderate Wavelength Range with Maximum Efficiency ra is said and done, the wireless amateur or experimenter mus} “sooner or later answer ' the al in making his choice of receiving apparatus. For it is a ‘oven fact that all re- , ceivin ave only been accomplished by sacrificing the wave wt range or ratio. The amate ys a short wave receiving set having more than 2‘ to 1 wave length ratio from minin ximum range is sacrificing efficiency. There is no other way out of this problem. ' The : finitesimal energy from a distant station may be far too weak’ to find its way through ’ a lare tion of windings; it must be detected by using a minimum of windings—the shortest ' path ne the most efficient circuit. P | Special Relay Receiver is the only receiver on the market which is designed with the i highe wave length range of ratio without sacrificing any of its efficiency. It made a reputat tself in recent QSS tests. It is now supplied with Grebe exceptional knobs; and, all in all ceiver can be compared with it. or — re Grebe Relay Receiver Type CR-3 $65.00 nd this receiving set, as well as other Grebe products, on sale at all live dealers. ilers, Jobbers and Distributors write for our discounts. Pacent Electric Company, Inc. REPRESENTING: A. H. GREBE & CO., Inc. s of Regenerative Receivers and other radio apparatus of distinction. : new catalog will be sent on receipt of 10 cents in stamps. DUBILIER CONDENSER COMPANY, Inc. rs of mica condensers for transmitting, receiving and laboratory work. stalog will be sent on receipt of 10 cents in stamps. RICHTER-SCHOTTLER CO. Manufacturers of dry batteries for vacuum tube work. Bulletin Rl is yours for the asking. THE MAGNAVOX COMPANY Man yud speakers, power amplifiers, voice and music amplifying equipment, etc. Bulletins on request RAWSON ELECTRICAL INSTRUMENT COMPANY ultra-sensitive instruments for precision and research measuring work Catalogue sent on request. ELECTRICAL PRODUCTS MFG., CO. Manufa Late pral Coils and other machine wound coils for radio and electrical equipement, r the asking Inquiries on special coils will be given our attention 150 NASSAU STREET Buckaee este NEW YORK CITY bo ALWAYS MENTION QST WHEN WRITING TO ADVERTISERS

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©Oc.B479213 OCTOBER, 1920 VOLUME IV, Ne. 3 ¥ eS SomN TEN ’T’S Bulb Oscillators for Radio Transmission L. A. Hazeltine 5 Radiotelephotophone Personalities ““Tewpieye” 9 Notice re QSS Tests 1] Concerning Cages Sumner B. Young 12 A Simple Radiophone Operating on “B”’ Batteries F. S. Huddy 14 An Oil-Dielectric Transmitting Condenser L. A. Bartholomew 15 A Paper on QRM John F. Gray 16 A New Variable of Radical Design 20 Editorials 21 The Operating Department 23 With the Affiliated Clubs—The Chicago Convention 31 Amateur Radio Stations 35 Another C.W. Problem Solved J.O. Smith 38 Strays 39 The Junior Operator 41 Radio Communications by the Amateurs 42 Calls Heard 49 QST is published monthly by The American Radio Relay League, Inc., at Hartford, Conn. Kenneth B. Warner (Secretary, A.R.R.L.), Manager and Editor. Subscription price, $2.00 per year, anywhere. Single Copies, 20 Cents. Entered as second-class mater May 29, 1919, at the post office of Hartford, Connecticut, under the Act of March 3, 1879. Copyright, 1920, by The American Radio Relay League, Inc. yw Title registered at United States Patent Office. THE AMERICAN RADIO RELAY LEAGUE, Inc. HARTFORD, CONN. WWW 1

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lent A\NAGER VISION wart Pa DIVISION ager er od Ave. MAXIM ICE, JI OFFICERS Traffic Manager F. H. SCHNELL 61 Waverly Bldg., Hartford, Conn. DIRECTORS F. F. HAMILTON Indianapolis A. A. HEBERT Nutley, N. J HIRAM PERCY MAXIM Hartford, Conn. Cc. A. SERVICE, JR. Bala, Pa. J. O. SMITH Rockville Centre, L. L OPERATING DEPARTMENT ec. WEST GULF DIVISION Manager Frank M. Corlett, 1101 East Eighth St. allas, Tex. ALASKAN DIVISION Manager Theodore A. Stockng Ketchikan, Alaska ROCKY MOUNTAIN DIV. er M. S. Andelin Richfield, Utah PACIFIC DIVISION Manager A. E. Bessey Sunnyvale, Calif. Assistant Manager G. Arnold 181 No. 17th St. San Jose, Calif. ST. LAWRENCE DIVISION Manager Albert J. Lorimer 243 Mackay St. Montreal, Que. ONTARIO DIVISION Manager A. H. Keith Russell 353 Markham St. Toronto, Ont. THE AMERICAN RADIO RELAY LEAGUE \ non-commercial organization of radio amateurs, bonded for the more ng of friendly messages between their stations, for legislative pro- tection, and for scientific growth.” Treasurer A. A. HEBERT Nutley, N. J. Secretary K. B. WARNER Hartford, Conn. H. L. STANLEY Babylon, L. L Cc. H. STEWART St. David's, Pa. K. B. WARNER Hartford, Conn. M. B. WEST Waukegan, Il. F. H. SCHNELL Hartford, Conn. H. M. ANTHONY Muncie, Ind. NEW ENGLAND DIVISION Manager Guy R. Entwistle 137 Sutherland Road Brookline, Mass. ROANOKE DIVISION Manager W. T. Gravely 854 Main St. Danville, Va. DELTA DIVISION Manager John M. Clayton 1301 Welch St. Little Rock, Ark. MIDWEST DIVISION Manager L. A. Benson 4942 Wiesehan Ave. St. Louis DAKOTA DIVISION Manager Russell H. Pray Valley City, N. D. NORTHWESTERN DIV. Acting Manager Royal Mumford 518 Beech St. Vancouver, Wash. ADVISORY TECHNICAL COMMITTEE TINE ARD, Jr. ‘RAD MINTON CRONKHITE J. H. DELLINGER c. L. FARRAND eneral Correspondence to Executive Headquarters, Hartford. Conn. PAUL F. GODLEY L. A. HAZELTINE Cc. D. TUSKA

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A Magazine Devoted Exclusively to Amateur Radio A Bulb Oscillators for Radio Transmission By L. A. Hazeltine Professor of Electrical Engineering, Stevens Institute of Technology 4 Presented at meeting of the Radio Club of America, Columbia University, April 30, 1920 PART L. Valves as Rectifiers and as Oscillators The unilateral conductivity of certain vacuous or gaseous conductors permits their employment as electric valves to al- ternately open and close an electric circuit, analogously to the use of mechanical valves to alternately interrupt and permit the flow of air or steam. The simplest use of a valve is to convert an alternating or in- termittent flow into a continuous flow; for this will be accomplished automatically by a valve which permits a flow only in one direction. Thus automatic valves are used in reciprocating air compressors to give a continuous discharge of air, although. the motion of the piston is alternating; and similarly electric rectifiers (such as the are rectifier, the Tungar rectifier, the Flem- ing valve, etc.) act as automatic valves to convert an alternating current into a direct current. The reverse operation, the conversion of a continuous flow into an alternating flow, can be automatically accomplished only by a valve which is inherently unstable; other- wise a positive (non-automatic) contro] of the valve is required, either by an _inde- pendent means having the desired fre- quency or by the alternating flow produced. The mouth-piece of a wind musical instru- ment and the ordinary arc oscillator are examples of mechanical and electric valves which produce oscillations by their inherent instability. Bulbs having considerable gas, of either the two-electrode or the three- electrode types, may be electrically un- stable and so ean act in this manner as electric oscillators, as has been found with some audions without the normal feed- back; also the dynatron, a particular form of three-electrode bulb, acts as an oscilla- Oscillators tor by reason of instability. having a positive valve control, however, are those in which we are here particularly interested, especially self-excited oscillators whose valve action is controlled by the al- ternating flow produced, as exemplified. by the steam engine and by the ordinary three-electrode bulb oscillator (audion, pliotron, etc.). In the steam engine the valves, which admit steam to alternate ends of the cylinder and so convert the continuous flow in the steam line into the alternating motion of the piston, are them- selves controlled by this motion. Similarly in the-three-electrode bulb oscillator the grid whose varying potential periodically interrupts the plate current and so con- verts the direct-current power supplied to the plate circuit into alternating-current power, is itself controlled in potential by this alternating current. Instead of this electrostatic valve control, self-excited os- cillators may have electromagnetic valve control, which has been practically applied in various ways. Electrostatically Controlled Oscillator This paper will refer specifically to the electrostatically controlled oscillator, em- ploying a bulb with three electrodes: the cathode, in the form of a filament heated to incandescence; the anode, often in the form of a plate; and the control electrode, usually in the form of a grid interposed between the filament and the plate. Electrons emitted by the filament by virtue of its temperatire leave the immediate neighborhood of the filament at a rate de- pending on the combined effect of the plate potential-and the grid potential, and con- stitute the “space current”. In all ordinary bulbs the effect of a given potential at the grid exceeds by. several times the effect of an equal potential at the plate, but this is

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not « ficati the tial re im spa grid | usual! unity the electr subicic I currer circuit hand, w to draw thus TA ing relat the bu practica electr« r and ev electror ae plate, on Thus the plate curr latter nor small. The ph may be ow-resistance paths t When the grid is negative, QsT October, 1920 In other words, the “ampli- ence to the separately excited oscillator tant” of the bulb (defined as of Fig. ia. The “exciter’” may be an alter- f the change in plate poten- nating current generator having a rectan- to cause a given small change gular voltage wave or it may be a nt, divided by the change in periodically operated reversing switch con- to give an equal effect) is nected to a battery. In combination with but could be less than’ the “grid bias” it causes the grid potential prohibiting oscillation. When to be alternately slightly positive and high- negative it tends to prevent ly negative, as represented by the wave e,, Ip aoe Lcentanel BATTERY SOURCE -F16.10—- “FIG. 16> leaving the filament, and if Fig. 1b. The highly negative grid poten- egative will reduce the space tial interrupts the plate current entirely, ro, thus opening the electric while the slightly positive grid potential rh the bulb. On the other permits the plate current to flow readily, e grid is positive, it will tend as indicated by the wave i,. The grid electrons from the filament, current (not shown) will vary similarly to » space current and oe 4 the plate current, but will be smaller. The plate potential (in this figure) will be equal electrons reach it, though *° the voltage of the “direct-current ass through it to the plate; source” when the plate current is zero, and the grid is positive, fewer will fall to a low value when the plate y reach it than reach the current flows (that is, when most of the + ; ep ip T eg FIG.2a-> -F/G.26.—- int of its smaller surface. voltage of the source is used in the “load”), current is made up of the as indicated by the wave e,. Evidently und the grid current, the’ the variations in plate potential are in the being zero or relatively opposite sense to the variations in grid potential; this condition is essential to the vction in a bulb oscillator production of alternating-current power mply examined by refer- and must be arranged for in self-excited

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October, 1920 oscillators by proper polarity connections. Conditions in Fig. 1 are simple and ideal. Each of the operating currents and volt- ages has only two different values during a cycle—the open-circuit value and the closed-circuit value. The internal losses in the bulb will be small, for current flows only when the corresponding potential is low. PLATE CURRENT. in. > GAIO POTENTIAL ,@g* -F/G.3> PLATE CURPENT, Ip. demo POTENTIALS 3* -F16.4.- Let us try to obtain the results of Fig. 1 in a self-excited oscillator by connecting the primary of a transformer across the load and the secondary in the grid circuit, as in Fig. 2a. If it were possible to have a transformer without exciting current, so that it would transform voltage but would not affect the currents in the circuits, and if all inductive and capacity effects were absent, then the waves of Fig. 1b could theoretically be obtained, though even then the frequency would be indeterminate. As a matter of fact, the transformer must take exciting current and the circuit parts must have capacity; so the simple results attained by positive valve control in Fig. 1 cannot now occur. Instead, we shall have the following conditions to satisfy: first, the variation in grid potential must be in phase with the variation in plate potential, due to assumed close coupling of the trans- former coils; secondly, the current must vary in phase with the two potentials, since these determine the current by their com- bined action; and thirdly, the relation of plate current to plate potential must be that fixed by the impedance of the plate circuit external to the bulb. The last two conditions together show that the external plate circuit must act like a pure resistance, inasmuch as its current and voltage must be in phase. Therefore an oscillation can QsT occur only at that frequency which will make the capacity and inductance associ- ated with the plate circuit resonant with one another and hence non-inductive in their combination. Usually in practice, the capacity and inductance are effectively in parallel and are sharply tuned, causing the plate potential, and thence the grid potential, to be almost free from harmonics, as represented by the sine wave curves e, and e,, Fig. 2b. The plate current will then be zero while the grid is highly nega- tive and will roughly follow the potentials during the remainder of the cycle, as repre- sented by the wave i, of the same figure. The grid current will vary in the same general way, but with a longer zero interval. Thus it is seen that the ordinary self- excited oscillator cannot have sharp open- ing and closing of the circuits through the bulb; but instead the valve action serves to gradually change the resistance of the plate circuit. Such valve action is analog- ous to the slow opening and closing of the valves of a steam engine, resulting in “wire-drawing”, or gradual throttling, and is undesirable for the same reason—loss in energy in the resistance (friction) inter- posed. Later in this paper will be shown (Fig. 11) a circuit devised and used by the author for giving sharp valve action in bulbs. As is well known the correspond- ing result in steam engines is one of the main advantages of the Corliss valve. For simplicity’s sake, the load resistance has been shown in Fig. 1 and 2 directly in the plate circuit and so will carry both direct and alternating currents having the same order of magnitude. In practice, oscillators are arranged, by the use of transformers or sharply tuned circuits or both (Fig. 9 and 10), to have a path of low resistance for the direct plate current and of suitabiy high effective resistance for the alternating plate current. The oscil- GPIO CURRENT dy. ° GRID POTENTIAL,€g + - FIG. §.-

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8 QsT lator erve to convert the direct- curre! f the plate generator or batter rnating-current power with an eff t compares favorably with that lectrical converting appar- atus er rating. The grid-bias b 4 €9 4 FIG GS TING UNDERLOAD — batt Fig. 1 and 2 is a sink, not a ywer, and is usually re- pla nee (R., Fig. 9 and 10) in ¥ lirect current will cause a | rop The plate generator and tance are shunted by conde rd low-impedance paths for t ng parts of the plate and grid ectively. racteristic Curves TI f the action of a bulb oscil- lator nined as described below fron eristic curves, in which the | rid currents are plotted aga tential for constant value plate potential. Fig. 3 show f “mutual characteristic cur rrent and grid potential, the 1 the curves representing -~ FI -~FIG. 78- = ENTING NORMAL LOAD. the re potentials, which are con- stant f irve. The “grid character- istic Fig. 5 are less important but a for a complete analysis; the gr nt is plotted against grid October, 1920 potential for various constant - plate potentials. it is convenient to plot curves showing the relation between the plate current and the grid potential, taking into account such variations in plate potential as occur during oscillation. These are called de- rived characteristics. Under ordinary con- ditions the changes in plate potential bear a constant ratio to the changes in grid potential, represented by (mn) in the equa- tion below (which is not, of course, the usual amplification constant) : de — n= constant, de de, and de, normally having opposite signs in order that power shall be given out from the plate circuit. The derived characteristic curves for this condition are shown by the full lines of Fig. 4, which are obtained from the normal characteristic curves repro- duced from Fig. 3 and shown dotted. To plot one of these curves— say P,P,P,—the increment de, in plate potential between the successive dotted curves is divided by - FIG. 83.- —FIEPRFESENTING OVERLOAO — -~FIG. 8a- the constant n, to give the corresponding decrement ( - de.) in grid potential. Then starting from any point on one of the dotted curves, lay off Se, horizontally, and draw a vertical line to the succeeding dotted curve. This gives one point on the new derived curve. In a similar manner other points on the new curve may be ob- tained. There will evidently be a different family of such derived characteristic curves for every value of n. Derived grid characteristic curves may be constructed by a similar process from the normal family of curves in Fig. 5. In Fig. 6a, 7a and 8a are shown derived mutual characteristic curves, which ere fixed for a given bulb by the alternating and direct components of the plate and grid potentials. Assuming sinusoidal vari- ation of these potentials, their waves may be plottéd as e, and e,, Fig. 6b, 7b and 8b, and thence the waves of plate current, i,; may be:-plotted by reference to the char- actéristic curves. Similarly the wave of grid’ current could be plotted, if desired, by réference to derivéd grid characteristic (Continued on‘ page 30)° ~

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October, 1920 QST Radiotelephotophone Personalities By ‘‘Tewpieye’’ This is the wildest story that has drifted into the QST Factory in many a day. these radiophones did it, we guess.—Editor. QRM from EN Muller (2BH, maybe you know him), while more or less a facetious individual, occasionally shows in- dications of at least mediocre in- tellect. During one of these rare manifestations we simultaneously came on an idea, which upon the manufacture of our next model will revolutionize the world! The name of the _ instru- ment, RADIOPHOTOSELENICOSCILLA- TORIOPHONE, is self explanatory. The idea of transmitting a photo or living image via land-line is old and to quite an extent perfected. However, the principles which are applied to such telegraphy must be abandoned when similiar attemps are made by radio. The solution, of sending images thru an application of wireless, was discovered, as above stated, thru joint and exhaustive experiments on the part of Hen and myself. Our principle, briefly, is something on the order of the Gold- schmidt Alternator, whereby we stepped up the frequency of our city lighting juice. The main variation from that commendable apparatus was seen in an auxiliary machine which in an entirely different manner re- duced the already short wavelengths to those of light. These extremely rapid os cillations were superimposed upon. still shorter waves (different degrees of the Ultra Violet), which we employed as carrier wave. The latter were generated by a two-stage application of the general principle. It is obvious that by tuning to the various frequencies of the carrier wave, an analogy to radio is found, and inter- ference from other Radiophotoselenicos cillatoriophone stations would be lessened We constructed a number of these machines and loaned one of each to certain amateurs on Washington Heights, giving them full instructions, and arranged, as a practical test, to have them all in operation at a set time on a given evening Hen arrived early, bringing me a stock of Bock Panatelas and we commenced tuning our rather complicated receiving apparatus. It might be mentioned that reception was accomplished by an appli- cation of the heterodyne idea, and its success on waves of such extreme short- ness necessitated the Nth degree of delicacy. The power stalled our had recently in- K.W. lines with company special ten which we operated our receiving mechan- ism, cnd I examined the connections, preparatory to opening up. Suddenly I gave a start. “For the love of Mike, Hen! You hooked this darn thing up with annuncia- tor wire!!!’ “Well it’s the only stuff I could find around,—and it’ll announciate the photos! Hi!” When Hen starts that foolishness ’tis best to pay him no attention, so I glared my disapproval and continued the investi- gation. SS MN RS), Ss = oe ER 2 , ; f ov i , | — af i jie UY Ze A . = Me CE, ‘ } — LIFE Y ) - > — Cee. iy : —— I reached forward and grasped the hundred amp switch. Looking at my watch I noted that it lacked but a minute of the time when the prearranged stations would be operating. I reached forward and _ grasped _ the hundred-amp switch. 2BH backed away (he always does when he fears something may happen), and I threw in the juice to our four alternators. As the machines gathered transfixed, gazing first at the bell wire, then at the ammeter which was slowly climbing. Ten, twenty, twenty-five, and finally wavered about thirty! “Wow!” yelled Hen, “That’s a regular electric stove—ha—ought to increase our receiving range. Ha ha! Get that? Stove range—he he!!” He ducked, but I was too busy to chuck anything his way. I tuned down to a couple of millionths of a centimeter and the platinum screen before us commenced to glow. Then changing colors it took on the appearance speed I sat

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10 QST The scene varied thru ’ if ition: all t the rainbow and continued to be This was no doubt due to the u f this very short wave. How e mental note that the still short e was stable. It sefore us was a_ perfect view te radio shack. \ raduated from a bright ern iring green Hen could not tation to remark, “H 1 ought to call this a C} A I isly and he ceased his Or f the set we were regard- ing s-range, announcing the a was situated at no gre from the _ kitchen. It wa e the long countenance wh audion before him, so we | recourse to the printed 2ABP wall. We centered our atter perator. He turned un- ea tove which was contin- him and his with the superfl ng frankfurters. nted Hen, “I'll bet thore some QRM, what say?” I policy of saying nothing. Th 1estion began to sputter a litt nd radio operator, Don Plu fearfully about for a fire- exti n suddenly the “picture” fade I explain this occurence, but H took the key. “9 A a om sum of tt grease spatt lens in front of the elet pe it of—HI—AR K” Sur the picture returned we beh« hand. The dogs were ther the direction of the dinit we QSY’d a few thou entimeter lower. Ay ame into “focus’”’ and we inte elves with 2LM. A huge sheaf idorned a hook above a one | which was sputter- ing yscillation-transformer lay it a shelf, while a wave- meter inently in the waste- bashet itor was industrious- ly eng t on the phones. We were ¢ the last of a long series of 3DI by an extensive array of 2LM turned off the bulbs Hen mutte1 ight so!”’, and we changed scene As | I lit a Bock Panatela and smoke y to nullify the odor of melted ow emanated from my annul quantity. The am- meter low but sure way to- wards t ark! The v kaleidoscoped to the compact f 2AB. We beheld its October, 1920 owner, M. B. Sterns, in a very peculiar position. Tho it was past eight and full time for his concert, he was meandering around the room on hands and knees! He first protruded his head in a waste-paper- basket, then extracting it with difficulty, he crawled about the shack in the most amazing manner! Hen suddenly left the room, returning a moment later with the telephone book. “Here you be, Jack; Matteawan one two six eight.” LUT “Sterns just shimmied under the bed!” Come Sterns “What are you talking about? here and watch this. It’s good. just shimmied under the bed!” “That’s just it, you can’t let the poor guy suffer like that. Matteawan one two six eight; that’s Bellevue; call ’em up and tell "em to send some men with a van up there!”’ I admit 2AB’s actions did look rather queer, but averred that we had better await developments, for if sane he might resent such drastic procedure. Sterns finally emerged feet first from under his bed, a smal] shiny thing grasped triumphantly in his hand. He rose to his feet and advancing to his phonograph started the show. He had been hunting needles! I threw the phone book at Hen and tuned in our next station. What closely resembled a shaving mug took the place of Stern’s shack. A thin cloud of steam wavered above this radio montrosity, and flickered green and blue. The “mug” must have been very close to the lens of the apparatus for nought else of the station appeared. Suddenly an enormous hand took the handle, and the cup disappeared disclosing to view a re- spectable audion control cabinet. The mug re-appeared half emptied of its contents Hen’s brow raised and I prepared myself

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October, 1920 for some facetious remark. “Home brew”, he suggested. The mug repeated the disappearing act and when it again returned the guiding hand held a Mecca cigarette. Light dawned ipon me It was merely 2QOK, friend Oscar, and his eternal cup of cocoa! This beverage finally left the scene for good watched the maneuvers of the cigarette. 2OK threw in his trans- ting switch, sent a few explanatory (7) V’s, and placed a book on his key. Having first donned rubber gloves he grasped the coffin nail with a pair of pliers and held it the spark!! As Johnson, ind we grave consumes a box of dollar 20K, I’ve butts per evening, sent in my to the National Anti-Tobacco League. It may help to reduce QRM! Above the operating table stood the re deeming feature of his shack, an A.R.R.L certificate, heavily framed. Hen noticing this grew excited and dancing on one foot proclaimed, “Hey, that’s a Hen, with the skill of dodged “Vacuum Tubes in munication”, which I accompanied the remark that the pun was the form of humor. As 20K commenced to relite his cigar- ette, I again QSY’d and my last glimpse of his station was of an O.T. in beautiful discard under his desk. At this juncture, Hen howled as he came Ha ha he he!”’ long expe rience Wireless Con with lowest frame up in contact with an incandescent bell wire and I cast a mournful glance at the am- neter. FORTY-FIVE amps! MIM! EEE : ~ « — — | STASHUN OAN\VI ? i aA AQ “galley” 2QV was likewise condemned to the As a couple of wash-tubs “faded” into existence on the photo screen I thought we had returned to 2ABP but the sight of a huge Dubilier condenser disclosed that 2QV was likewise condemned to the “galley” QST 11 “Say, his set has a rather tubby appear- ance! Haw haw!” chirped Hen. I looked threateningly at a copy of “Practical Wireless Telegraphy”, and he obered down. A mass of machinery operating a break- in-system was the next most ostentatious istrument in the shack. An oscillation transformer stood to the left and I noted the — ty of the primary to its better ialf. Under the table reposed a Packard former and next to it a galvanized tray Vl ALIS garbage-can. Henry backed to the door and yelled: “Say these guys who are stranded in the kitchen would make good aerials! Haw, law; get that? Stranded!” I contemplated murder and was serious- y considering how I might hook 2BH to the ten K.W. line when a peculiar looking nstrument in 2QV’s shack attracted my attention. It was a large, well-worn clamp, affixed to the table, just one side of the cey. Its use was obvious. When friend DePalma desired to test he merely swung the clamp around ’til the key was closed It remained there until the termination - the test, incidentally a period of about o1 ialf hour. I looked in vain for a time clock operating this unique contrivance, set for about eleven P.M. I tuned a little closer and the cook-stove nto focus came “Say”, quoted the irrepressible Hen,” I’ll bet that’s a BAKELITE stove, and by the way, with that right next to him he ight to have Haw he I threw every thing within reach and as Hen jumped he slipped in a pool of molten wax, which, eight o’clock, had been ccumulating in puddles beneath the an- nunciator wire. As he fell, he grabbed my light extension. My last impression before the wire snapped and darkness prevailed quite a transmitting range! since as the scale of the ammeter. Fifty-six imps! The glowing bell wire sparked fitfully in the dark. A little ball of white formed on one and quickly enlarging dropped to the floor in a blinding display of pyrotech- nies. The alternators, with a final whine, came to a standstill and the fused wire cooled to a dull red. NOTICE On Tuesday and Thursday nights dur- ing October, between 10 and 11 p.m. Eastern Standard Time, the A.R.R.L. will conduct another series of Fading Tests for the Bureau of Standards. Stations in northeastern quarter of country will be engaged in recording—details later. All stations are requested to confine their transmitting to a minimum during these periods, to prevent interfering with the recording.

Page 14

QsT October, 1920 Concerning Cages By Sumner B. Young, 1AE e are seldom used by use their merits are known, and because erial of conventional er and cheaper to e cage has ele-trical ntages which should Relayers who desire i it should prove » erect an aerial is winds must be with- n build a cage; care ne e3sential. a E Mar. 20—June 24, 1920. led that the flat-top omings. Radio fre- g it flow mostly just as these to run along the ribbon. The losses they are of im- ellence is sought. ist be fastened to the not only add weight, yr they offer four is to earth, blocked ch is never absolute. are disadvantages of The spreaders of a ierial are long and thing to the electri- tenna, and are always ffer considerable sur- Their contribution is negligible. of the cage is ad- it, every wire gets the load when high equt flowing through the cage metal rings not only helt s equal current distri- rease the _ electrical Further- eme na system. more, long lead-ins may often be avoided, for the cage takes up little space and can be brought closer to the operating room. ‘ Sway-guys are eliminated, for the wind whistles through a cage instead of tossing it around. The diagrams give specifications for a cage wel] suited to amateur requirements. In building it, the following procedure can be followed to advantage: l. Bend the rings to shape by hammer- ing them around a circle of heavy spikes driven into a wooden shaped like the spokes of a Wrap the joints and solder. 2. With a file framework wheel. mark the places on the rings where the aerial wires are to be fastened. 3. Cut the aerial wires to proper lengths, allowing a few extra feet, and coil them separately. 4 Solder one aerial] wire - to the first ring. 5. Select a clear spot in the Fasten this ring securely to the side of the house so that it will remain in a vertical position and will not slide around even if considerable pull is exerted on it. 6. About 65 feet away, set up a post, and fasten to it a large board parallel to the side of the house to which the ring is fastened. Draw a two-foot circle on this board, and drive screweyes into it, spacing them sixty degrees apart around the cir- end of each back yard 10-wire cage to be used at 1AE this winter. cumference. 7. Uncoil the antenna wires, fasten the free ends to the proper screweyes, and ad- just to equal tension. 8. Tie in the rings, using short lengths of #16 bare copper wire. 9. Solder the _ tieing-in aerial wires and to the rings. wires to the Use jumpers

Page 15

13 ” J October, 1920 Q where good electrical connection is doubt- ful. Apply the solder at the ENDS of the tieing-in wires so that the aerial wires will net be stiffened where they meet the rings, and rendered liable to breakage This soldering takes time and care fo the rings absorb a great deal of heat A soldering-iron weighing at least three pounds must be used. The cost of the cage described above will be about fifteen dollars. This figure can be greatly reduced by using galvanized iron instead of copper separator rings However, iron is heavier, and the joints between the wires and the rings are som what subject to corrosion. Wooden separ- ators such as bicycle rims and cross-arm arrangements will serve, but they are cum- bersome, and put the cage at the mercy of the wind. They do not become part o the aerial itself, nor do they assist in dis tributing current equally between the wires of the cage If possible, install the cage so that a long lead-in is unnecessary. If this cannot be done, it will pay to build a miniature cage about six inches in diameter to take its place. Cables are poor radiators, and often poor conductors. It is significant that the down leads from the flat-t: to from March 28th, 1920, until the station the outdoor tuning inductances of the was closed for the summer oa the 21th of Alexanderson multiple-tuned anten: at June. A conservative estim:te, based 0. (8 Llectrase O°’ Lect70se ; ARCQuTed /3 “2 eclrose ix Aerial Wire Copper Tube No.12 Bare Coppe Solder Filled Short Leadin(Cable )~ Marion, Mass., are cages, and it is pre- our Log Book, is that it added 100 miles sumed that this construction is dupliccnted to the station’s range. The other cage is at other high-powered stations of the Rado of equal length, but has ten #14 wires Corporation of America. spaced 36 degrees apart around three- The photographs show two cages which foot copper rings. It received its initial tests on August 23rd, and a 10% increase Solder ae eee on in the reading of the hot wire meter noted. i a, pe ype es This cage was built in two sections which fr . ————- were joined together after they had been | % 2) \\ & SS hoisted to the roof. 7 \ File Rod thus at t During the coming season, the author’s \Y J business will keep him away from home a i SS” great deal, yet he hopes to “sit in” Satur- A Separator RING days and keep folks from forgetting the sound of his spark. Perhaps “The Old The smaller consists of four wires 55 feet Man” will call him some night and describe long, and has galvanized iron rings 18 a cage he has invented to shut up the radio inches in diameter. This was in service pests he rants at. were built by the author and used at 1AE.

Page 16

QsT

October, 1920 A Simple Radiophone Operating On “‘B’’ Batteries By F. S. Haddy, IIl is a description of my ephone outfit. Enough ven to make it easy for e experimenter to make Many improvements egest themselves to the - the outfit. Let it be not a high-powered set. I 10 miles on 5 watts and ng distance traffic. It 1ade and with 100 volts transmit 5 miles with a type of tube to be idgment of the maker. I ng a Western Electric \ ) ilb. e been used. Almost oscillate with 50 volts The Marconi class I] e if the voltage of 500 is every experimenter has

NP VIIT\ fe) {az s disposal, the W. E. practical as they will te at a much lower H-7 |, % | > a 3 ere : 5 * terials will be needed: ttery rheostat tery ‘phone transmitter witch switch y buzzer yne condenser ite pane] 12” x 12” 5 mfd. or variable A irawings will show how the re mounted. The small switcl t of the microphone er to talking circuit, and

in its center position opens the battery circuit. A key is connected to the bind- ing posts in the lower right hand corner of the panel. By shortening the buzzer and conhecting a long flexible cord to the key binding posts, an extension microphone may be connected in, which is convenient to place in front of a phonograph.

A WLS TS ok ae oO OV ° fo) ef\e v s—jo C ot MICROPHONE > po, (@) — pe BUZZER. @ © 4v sf — i | KEY The tuning inductance consists of 53 turns of No. 18 bell wire wound on a tube 5% inches in diameter. Starting from the bottom, taps are taken at 20, 39, 43, 48, and 53 turns. T, is the tap taken at 20 turns. The others run to switch points of the wavelength switch WLS. C, is a 2-mfd. telephone condenser, while C, has a value for best results in my set of .005 mfd. and might well be a variable. MT is the Ford coil. Uncle makes good modulation transformers. Henry The

evo

| | c= ) Nx : 7 I cvre ~ (<

PANEL a one I used transmitted the speech perfect- ly and without distortion. Switch TS is used to change from the microfone to the buzzer. The buzzer is connected in series with the battery and key. Anyone interested in the construction of this little outfit and who does not under- stand my description, is invited to write me at my residence at No. 204 Bowen St., Providence, R. I.

Page 17

October, 1920 QST 15 An Oil-Dielectric Transmitting Condenser By L. A. Bartholomew, 6LC. ERE is some firsthand dope on a condenser that will not “blow” when needed most. It is of the oil dielectric type, quite simple to construct; but expensive, as every- body finds out who makes any kind of a transmitting condenser. This one takes 70,000 volts to puncture; that is, the con- denser will puncture if the voltage is allowed to build up to that figure. This does no harm whatever. A _ bubble rises to the top, and the condenser is ready for the next shot. The losses, also, are very small. The material needed: 2 Bakelite end pieces, %” 38 Aluminum plates, ‘oo ike . 152 Spacers, round brass tubing, 4” O.D. and yy” I.D., +4” long. 8 Spacers, ditto except %” long. 8 Round Brass Rods, #” diam., long, threaded 8-32 for 1%” end. 16 Hex. Nuts, 8-32, Tank and Oil. The Bakelite end pieces carry the eight rods, on which, separated accurately by the spacers, the aluminum plates are mounted in two sets, the longest dimension of alternate plates being at right angles The drilling of the plates and the end pieces is the are given in x 14” x 14”, No. 16 gauge, 21%” on each and washers. first step, and the dimensions Fig. 1 and 2, respectively. The 8 supporting rods are then put thru ene end-piece, with washers and nuts be- hind, and the piece laid flat on the bench with the rods in a vertical position. Put short spacers on one set of four rods, and long spacers on the other set of four rods. Put on two plates (automatically at right angles to each other), and then another set of spacers, this time long ones on all 8 rods. Then another set of plates, etc. When half the plates are on, connect on the terminals to the center plates, which is done to make the current path as short as possible. These terminals should be at least 1 inch in width, and preferably 2 inches. Then put on the rest of the plates, finishing with the remaining set of short Ls te ad “deeded he on aneesensoe o--p+ ' | ; * J" aes ¥ : ' ' ' | ' ' . i ' : I i ‘e) + ' . | % ; “ ' ! ° ! ' 1 ' ' ' ' ! ! t ' | ' i ! ' ' i ' ! ; %" i -}--0----4 SSS uw memes $~+ {;- | se FIG. / spacers, and finally the other end piece. Fasten the ends with hexagon nuts, and draw up tight. Make a tank of galvanized iron and put the whole affair in. Fill with Mineral Seal or any good high-flash transformer oil. Above all things, use heavy metal for the plates—No. 16 gauge aluminum is_ the best. I used scrap stuff, which was very low in price—the new stuff is expensive. These plates must be spaced at least 4” apart, and ¥&” is better. This design gives fs” spacing. Use oil perfectly free from moisture, and let the condenser stand at least 24 hours before using, to let the air bubbles rise. In drilling the plates, stack 19 plates in each stack and clamp to the bench in any convenient manner, and drill the four holes right thru the pile. This insures alignment. A Ye” hole is about right. Place one plate of each pile on a Bakelite end piece in the same way they will be when assembled, and drill the end pieces thru the holes in the plates, using them as templates.

Page 18

QST nstant of Transil oil is kes quite a large con- great capacity. The here described is \ photograph of a hown, but having but enser and a capacity of ng designed for hich tone With it I get 9 al with a 1200-per-s°c 600 er sec. and less e larger condenser here 007 mfd ) is in us? antenna current is 9 a spark frequency of est 6ER could do with s about 6 amps. 6HS ng the oil type of con- information will help having trouble with =

October, 1920

s+ a —— eee Py | ° = ay a — . A244 b ~ tH :F yi 2 | | | H. | : ;° ° j bs yj, om occoee = {- |} a y BANSLITE as &. A Paper on QRM By John F. Gray, 6MZ esented before the Sunset Radio Club, San Diego, Cal.

article as the best we have ever seen on this important topic. We have talked much of co-operation, and we reiterate that it In this splendid paper Mr. Gray defines the practical methods in ndividuals alike. difficulties. It is a most vital ation can be applied. With all the earnestness there is in us, we commend these ndividual amateurs of the country.—Editor.

ired radio club meet- ‘f any hundred issues gazines, you will find it a meeting or an issue ot contain some discus- yuestion. And no mat- or write about it, stay pretty talk seems to cation is more or less nee, but the situation amateur work. When about it, this is not so body expects very good party telephone. So ect to talk to whom- henever we please, on i-party-line of two hun- en you look at it that wonder that we ever suc- each other at all. pe to do away with QRM spparatus of anything like continues to be used— yt hope to do away with it ng to restrict the use of ns a night, two stations an hour, or something on that order. All you can hope to do is to try to hold down unnecessary and avoidable interference to the point where a fellow doesn’t feel like breaking up his set with an axe and taking to drink—if there were any drink to take to. That’s what I am trying to get at here, but just how far I shall get remains to be seen. As heard from 6MZ, the San Diego Dis- trict seems particularly fortunate in this matter, This may be partly because we are out of the range of the spark coils, but I do not think it is entirely so. for the sta- tions we work in town are able to copy us pretty much any time they answer a «all You fellows in town may think the situa- tion is bad, but San Diego cannot be put in the same class with Los Angeles, where some suburban stations are not able to reach town through the QRM barrage for weeks at a time It is said to be even worse in some of the eastern cities. All the same, whether we are to be con- sidered good or bad as cities run, there is no doubt that we can stand a lot of im- provement.

Page 19

October, 1920 There are any number of classes of QRM. There is the hard boiled kind— the fellow who hogs the whole air when- mind to, and thinks QRT was I have ever he has a invented just to make him laugh. never heard him in the San Diego air, I 1m glad to say, but if he ever is heard we ill know what to do with him—turn him in to the radio inspector—do it quick, and don’t mince words about it. I wish the rest of the classes were as easy to deal with as he is. And there is the bone-head kind. He isn’t quite as easy to deal with as the hard boiled because the poor fellow was born that way; he may mean all right but he just could not help it. When you bawl him out, he feels awfully bad about it usually, apologizes all over the place, promises never again—and then goes right back and goes at it just as bad as ever. s calling with- QST 17 Club, though) who sends a hash of dots and dashes that sometimes could not be read by the best operator licensed. Being used to it, I can make a pretty good job of copying him on his good days, and I often get a lot of fun out of listening to him chewing the fat with some poor guy who is hearing him for the first time. If it was not for the call letters you would never know they were talking to each other, as neither of them are saying any- thing to do with what the other has just said. This sort of thing is not QRM it- self, but it is the cause of a whole lot of it because it ties up the air with a lot of stuff that might as well go unsaid, or if they are trying to say something that re- quires an answer, it causes one or more QTA’s that need never have been given. And we have the station with the wave like a barn door that comes in equally well anywhere you His specialty out listening for more than want to tune your receiver. thirty seconds or, even worse, Mr. Kruse’s Paper There are a number of them just throwing in his switch ao tho Deseo in San Diego, in fact they are and pounding away on the about the only serious cause key without ever bothering to of Standards— of complaint that there is listen at all. It never seems A.R.R.L. Fading here. Theoretically every to get into his brain that it Tests unfortun- amateur station, or nearly takes at least thre minutes ately could not every one, is tuned on two to really find out if the air is hundred meters Practically clear. He doesn’t realize that be made ready there is enough variation be- the station he is calling may for publication in tween most stations to enable be copying someone whom he, this issue. Waich fairly successful tuning out } self, cannot hear at : "i or for it IN THE of ce e, my bea the if he does hear him he does interfering stations have sharp not realize that the station NEXT ISSUE. waves. You cannot tune out he wants to cal] is the one a broad wave because it that is being worked, because comes in just as well one he does not have the sense wait place as it does another. If one transmitter to hear a few call letters and learn who is working whom. He has other specialties in the same class but that is the worst one. San Diego is free from him, but I hear him once in a while. A little more listen- ing would save a lot of wasted juice and a lot of hard feelings too. Then there is the fellow whose speed limit for receiving is about three words a minute. You tell him QRT, QRW, QRX please, and he comes right back at you with “Your signals are fine and strong, old man I have put my coupling two inches closer, how do I come in now?” All spelled out without a single abbreviation. More often than not he is ashamed of his bad copying and will not let on what the trouble is when you are talking to him. There is no crime in asking for QRS, but this fellow would rather let you QTA till you get a sore arm, or until] you finally do discover his secret and hand him the code at a speed where he can take it in On the other hand, there is the high speed artist and the fancy fist fiend, or both combined in one. There is a fellow near San Diego (he is not a member of the is tuned to a hundred and ninety-five meters, and transmits a wave of that length only, and another transmitter is tuned to two hundred meters, and transmits a wave of that length only, you can tune your re- ceiver to hear only one of them, if it is selective enough. But if one of these transmitters has just as strong a wave on one hundred and ninety-five meters as it does on two hundred there is no way for it to be tuned out, and the other station still heard. Some time ago I tuned in a report to the chairman of the QRM committee on the subject of broad waves. The report had scarcely been mailed before the two sta- tions most complained of had changed their broad waves to exceedingly sharp ones, and a station that I had given a fine boost went and came out with a wave that was QSA through one hundred and eighty de- grees of the series condenser. What I am driving at is that it is hard to lodge a com- plaint against any particular station, be- cause we amateurs fool with our sets so much that what is the truth about some body’s wave one week will be the reverse

Page 20

18 QST s a station in town that now, but two or three ve i him QRK on two thous- e it or not as you like. e coupling to get him ced is that we bear in 1enching good and our se the hot wire closer you put much temptation for reason that the more the more noise they r They do not or will ammeter reading simply means that ole lot of different hich is of any great of all of them makes eter fine and hot he amperes into the does not mean any eatin them away not want Keep your rh for there to be just nd what energy does ll be concentrated in just becau er, the gh i out all over the air QRM. I notice that a good re making the discov- eir spark rate is the get into their am- cht as far as it goes but re going at it the wrong nt a lower spark fre- low down their gap by for an experi- get by as a permanent r that the first duty to quench the oscil- ircuit and to open will not absorb back aerial circuit. Just and a musical note » of the rotary. Once t lations have been given ve usefulness of the led and you want to h it as soon as pos- have decided on the the best radiation, that suits your taste I is to speed up the t will take and cut dow f electrodes in the mo- will give the fre- quer fter. There is no such thir eed for a gap motor. Ar t causes a lot of trouble 5 t ywer for talking to a mar vn. There used to be San Diego although the fe rning better ways now. A nu I have had to give up trying rrams from the north rye tor at a ore n evening just because October, 1920 some amateurs in town were talking about the weather or kidding each other about their girls on full one-half K.W. When you want to chew the fat with the man in the next block cut down the input with a mag- netic shunt or a rheostat to the point where he can just get you QRK. Or if you haven't got either of these loosen up the coupling to get the same result. A hinged oscilla- tion transformer is a help in this method, and if a little QRM spoils the reception of the man in the next block do not begin to lose your temper and give her full power It does not hurt to QT. A, “Did it rain much over your way tonight?” In talking about spark frequency there is one thing I might have added Although there is not much doubt that a low tone gives better results on two hun- dred meters in most cases, this is not always so and it seems t bad that every- one in San Diego is taking up a low note When stations have widely differing tones it is possible to do some selective tuning by what is called the group frequency method, by a variable condense r across the phones. And even if you cannot tune one out it is still fairly easy to read either a high or a low tone transmitter even when both are coming in at the same signal strength. The fellow who is content to stick with a high tone may not be able to break all the long distance records but he will be able to get his messages through most ordinary QRM, and day in and day out that is what you are trying to do Average amateur work is down within a radius of a hundred miles or less. One thing that can be given attention is the habit that some men have of making a string of unnecessary signals. One KA is what the law requires, three or four KA’s are a violation of the law as well as a waste of valuable time. And when you have once established communication with a sta- tion there is no need of calling him the three full times, unless some exceptional condition makes it necessary. The same thi ng applies to calling a very near-by sta- ion, when you are fairly certain that he is on duty. Try him with a single call first and if that does not raise him the three repetitions can be used And do not fill up the body of the message with a bunch of periods, dashes, and HI’s. That does not mean to leave them out altogether if you like to use them but it does mean not to put them between every other word the way some operators do. Also I see no reason for signing off with your call letters at the end of every message. The man you are talking to knows who you are and as long as you are QRW it is nobody’s business. When you give your sign-off with the SK, it means something because it tells men who are standing by what stations are clear for new business.

Page 21

October, 1920 This about covers the matter of the QRM that we can all get together to stop in our every day sending. It leaves two big questions that are now being considered by nearly every radio club in the country as well as by the American Radio Relay League itself. One is the question of different classes of amateur wave lengths. And one is the question of a division of the time for Re- lay League messages. They are both sub- jects which should be seriously considered but I think it is better that they should be freely discussed by the Club at some time rather than be gone into at great length in a paper. There are two general classes of ama- teur stations: those that by reason of their low power do most of their communication within a radius of twenty-five or fifty miles or less, and those from a quarter to one K.W. that do inter-city and genuine long distance work. The big fellows need every bit of two hundred meters both because a longer wave length carries further, and because they need as much condenser as possible to use the power available. The smaller fellows cannot by any chance work much over fifty miles or so, nor can they use .007 or .01 microfarads. They use the two hundred meter wave mainly be- cause the law allows them to and not for any particular good that they get out of it. They would do exactly as well on a hundred and fifty meters, in fact they would do even better because they would be able to keep on working when a high power station in the same town was transmitting, and not be drowned out as they are now. At the same time the QRM for the larger trans- mitters would be reduced by one-half or even more. I cannot see that such an as- signment of wave lengths would do any- body any harm. Of course we would not expect the law to be changed or anything like that but it does seem that some agree- ment would be arrived at among the mem- bers of the clubs, between the various near- by clubs, and possibly throughout the whole country, by which some such assignment of wave lengths could be brought about. Let’s think it over. Then as to the division of time for Re- lay League work. I am one of those peo- ple who believe that the biggest thing in amateur radio is the handling of messages. It is the most instructive part of amateur work—in the long run it is the most inter- esting, and it is certainly our very best advertisement. When a man is a really good League operator he is fully trained to be a first grade commercial operator, if ever he should want to be one. In fact in most commercial work where they have cast-iron rules about unnecessary signals and con- versations, not to speak of their high power QST 19 sets, it is easy sailing cOmpared to ama- teur relaying. To see the way a good re- lay station gets its messages off the pin in the face of all the difficulties with which we have to contend would make a commer- cial sit up and take notice. If it had not been for the training furnished by relay work, the country would have been hard up for radio operators in the war. Then again—sooner or later a fellow gets tired of just chewing fat with anyone who will answer a CQ. When you know all about the sets of everybody to whom you talk and when they have heard all about yours, you begin to wonder what to talk about next. I am not trying to say that it is not good fun to pass the time of day with somebody in the next town or in the next block for that matter, for if we all felt that way about it we might as well join the Marconi service and get it over with. All I do mean is that we need some- thing to keep us on the job and to keep up our interest. Relay work furnishes just this. As to advertisement for amateur radio, about the only way we can keep the public informed that we exist and that we are doing serious and valuable work in the art of radio communication is by furnishing a sure-shot relay service,—not child’s play, but something on a par with the commer- cial companies. And if we want to stay in existence we shall need every bit of advertising we can get. Every time they talk about a new radio act in Washington, it means danger for the amateurs. When a station has a message to handle he should have the right to ask any station who is simply conversing to QRT, and what is more that station ought to be made to do it. There should be one, or better, two periods per day set aside for the exclusive handling of relay messages. To avoid con- fusion, certain stations should be desig- nated to do relay work in regular order, two at a time, one to handle traffic and one to stand by to help if necessary. If we do something like this we shall be able to clear all San Diego traffic, North and South, in at most two hours out of the twenty-four. As it is now, San Diego is on the black list of the Pacific Coast Man- ager of the A.R.R.L. as having rotten ser- vice. * As it should be, situated as we are, we should have the best service on the Coast. To make such an arrangement worth while we should have an agreement with the Los Angeles club so that they can re- ceive our traffic when we are ready to send, and so that we can do the same for them. I am sure they would be glad to do some- thing along this line. *San Diego was on the black list per- haps, but it is no longer. The co-operation there is most admirable now, and we know they have a hard struggle working through NPL’s arc. —Editor.

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20 QsT October, 1920 A New Variable of Radical Design Mfg. Co. have developed pe of variable condenser and interesting design, the most compact, practi- ble condenser that we have a maximum capacity of 001 size of the unit is only 3” d ” thick. Sor ivantages claimed for this r t has a lower minimum capa average air condenser, as the r of plates in proximity zero position have be t is practically unbreak- able, 1 no plates to get bent and hor s absolutely balanced, ur one hole in the panel to e the Ar lvantage is that two or mounted on the same portionally higher capa- city w ip hardly any more space. Fr ynal drawing illustrating the it will be noted that three discs al one of fibre, one of mica, and o1 iloid, the mica disc bein Between the celluloid an mica s a semi-circular tinfoil plat one of the condenser plate and mica discs are separat the periphery by a soft rubber washer, and at the centre by a which also serves to make th the mercury with which the lov f the space is filled. A bras all the dises together at the c« makes contact with the metal \ metal ring fastens the discs ¢ t the periphery and makes tinfoil plate. This ring th a pressure of five tons of the mercury im- contact is clam} maki upe possibD f Contr nade from one side of the circuit t ering lug on the shaft, and from th de, by a flexible wire, to the ter the ring provided for this ferred this contact may be purpos made by a strip of spring brass mounted on the back of the panel and bearing against the ring. From the abeve it will be clear that the tinfoil plate constitutes one of the con- denser plates, the other plate comprising the body of mercury confined in the cham- ber between the mica dielectric disc and the fibre housing disc. Since the weight of the mercury causes it to always remain in the lower half of its chamber, that is, in a _ substantially stationary position, while the tinfoil plate will rotate with the condenser, it follows that by the rotation of the instrument the semi-circular tinfoil plate may be brought into full or partial registration with the fixed semi-circular mercury plate or placed completely out of registration with it, thus varying the capacity of the condenser in accordance with the areas in register. The transparent celluloid cover allows the operation of the condenser to be seen, and facilitates the original setting in the zero position. These condensers, the manufacturers state, after having been thrown around a room, have been tested out and found to function perfectly. They should fill the long-felt want for a rugged, low priced variable condenser. THE DIRECTORY OF CALLS HE long-looked-for Department of Commerce’s List of Radio Stations of the United States is now promised for delivery early in October, and QST is therefore omitting the two pages of calls which have been appearing each month, as they would be calls contained in the government list in all probability. As soon as this list appears we will resume, taking up the lists where the Government edition stops. The new list is to be published in two parts this year: one part to contain govern- ment, commercial, and special stations, and the other the amateur stations. The sale price cannot be determined until the cost of publication is known, but it is ex- pected that the figure will not exceed fifteen cents for each list, possibly but ten cents for the amateur list. Remittances for these lists should be sent to the Superintendent of Documents, Government Printing Office, Washington, D. C. Let us take this opportunity to say that that is also the correct address from which to obtain copies of the Radio Laws and Regulations of the United States (con- taining the list of “Q” abbreviations), the price of which is fifteen cents.

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7 October, 1920 QST 21 DE AMERICAN 0 RELAY LEAGUE The Chicago Convention MATEUR Radio saw its high water A mark at Chicago on September 2, 3 and 4, 1920, when the Central Division held its first Convention It was strictly an A.RR.L. affair given by the Ravenswood Radio Association, South Side Radio Association and the Progressive Radio Association of Chicago in true A.R.R.L. style. From the meeting of visitors at the different railroad stations with automobiles, to the taking them back to the strtions, everything moved with that snap and precision which is characteristic of the energetic mid-west It was im- possible to determine the number of ama- teurs present on the three different days, hut between three and four hundred is a fair guess. It was a great treat to see the different fellows, with their cal] letters and their names on the blue and gold badges Most of them we all hear in the air here in the eastern half of the country. They looked verv different than we expected, as is always the case. Locomotive engineers, telephone experts, electric light men, Catholic priests, insurance men. business men and students were among the inter- esting personnel. Their ages impressed vs also. Mr. Bookwalter, who came up from Springfield, Ohio, was a young enthusiast of eighty-four summers. and SCP. whose examination papers at the Radio Inspector’s office are kept on exhibit ®s an example of a perfect examination paper, was in short trousers and boasted of fourteen summers. They were everything in hetween and the great average seemed to be around twenty-four. At the meetines, of which there were three, as reported elsewhere in this issue, it was also a great treat to hear the views of the different fellows whose names are so well known to us. The peppy spirit of general co-operation as voiced by residents of the First. Second, Third. Fourth, Fifth, Fighth and Ninth Radio Districts made one feel that we were actually the one big family we talk about in our QST, and the Technical meetings made it very plain that we certainly have the identical prob- lems on our minds, no matter where we live. The Fellowship Meeting, the final effort, was an exhibition of that curious brotherly spirit that animates us amateurs. The “stunts” that Brother Mathews pulled off made the banquet partake of the qualities of a big friendly party, where everybody simply loosened up and had a jolly good time. We know we did and we are willing to make it a pretty big red apple that everybody else did also. The Convention out-convented anything yet pulled off in Amateur Radio, and the rest of the country is under obligations to the fellows in the Central Division for setting the standard of what can be done and giving us a living illustration of the magnitudes involved in our A.R.R.L. We lift our hats to you, Mr. Mathews, Manager of the Central Division and leader of this greatest of all Amateur Radio Conventions, Mr. Schnell, Chairman of the Executive Counci] of the three Radio Clubs, and Radio Inspector Kolster of the Ninth District, Chairman of the Trial Board of the Executive Council and all around good friend of the Amateur. We hope you will try your hands next year and we look for- ward with the greatest pleasure to being present. An Anniversary amateur effort, the wartime restric- tions on amateur transmission were removed and we amateurs picked up the threads of our operation where we had dropped them to go into uniform. A year ago we were a band of young hopefuls, dusting off old apparatus because it was close at hand, eager to get on the air but brimful of service-gained ideas, and filled with the resolution that Amateur Radio should be made a greater thing than ever before. How well those dreams have been realized! What vast progress in our activities this one tiny year has seen! Our relaying network has been built up to a better-operating machine than ever before; the quality of our stations as judged by theix performance is incom- A year ago this month, thru concerted

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rn ss) t paral pre m the « numi most repeat ber ful « been partn teur 5! est ductic missi« And repeat conne happer to ma ventu of “seas whicl coast can equi} with heer their that effici« the ta ment Old ‘ equal out of in ther Our Ad, HIS T? be rer Board come Techn were QsT or; we have played a in the effort to determine elusive QSS; one of our een heard in Hawaii and al- er amateur record has been ashed; we have held a num- st enthusiastically success- ns; we of the A.R.R.L. have recognized by several de- f our government as the Ama- rd-Bearer; and, perhaps great- ve have witnessed the intro- nateur Vacuum Tube Trans- marvelous year it has been. ire? Gentlemen, we have ned to prophesy anything amateur affairs, for things » swiftly with us amateurs ife. We do not hesitate to er, that the achievements winter will make last ke the vacuum in an audion, lea of nothing. Coast to not? The Azores? Who reat improvements in our methods—new develop- 1estionably! year for us which is now fellows. Get the old junk in ‘er the juice—the gang is Romance old timers complain that romance in tube trans- has no individuality or ations like the old spark, t they are, to a certain ex- work is new, most buzzer ke, and indeed there is a and hearty attraction nonsink rotary, noisy and t is. We have had them ears; all our good work has em, and there is romance in ld note. But we do believe have to give way to the more t, and it seems to us that ance is merely the last argu- dwindling members of the As for Romance, what can mance of getting something little bulbs that have nothing isory Technical Committee will see the launching of our f Direction’s “Technical Com- idea. Our President, it may ered, was requested by the vite certain gentlemen to be- ers of an A.R.R.L. Advisory ommittee. These gentlemen vding radio engineers of the October, 1920 country and of Amateur Radio. They signified their pleasure in accepting the invitation and at the last meeting of the Board in New York their functions were discussed and decided upon. They will be supplied with certain data and their in- terpretation of this in terms applicable to amateur radio engineering will be re- quested. In time all of the great prob- lems at which we now must guess or at most proceed into by purely empirical methods, we hope to see put down in precise and exact form and the laws that govern them we shall expect to have set forth. We shall make it a point to see that the language and methods employed are clear and distinct and susceptible of practical use by the average well informed amateur. We expect great results. We all know how we would like real author- itative advice on many of our problems. This plan of our Board of Direction aims to get this advice, and incidentally to ele- vate the technical standards of Amateur Radio generally. More later, on this in- teresting subject. Canadian Relaying HORTLY before the summer strays S t really bad, regular communication tween Canadian and United States amateurs was just getting into its stride for the first time. Reports from Detroit and Buffalo show that the Canadians were being heard well there, and in the St. Lawrence Division Montreal was QSO 8BB and 2TF, and Farnham (Quebec) was occasionally working 1FV and 1HAA. With the coming of summer navigation in the St. Lawrence Valley, the Canadian amateurs reverted to their original 50 meters—which is perhaps just as well this first summer, for they will come back with renewed vim when the longer wave length is again permitted this winter, and then we shall see the result of the pioneering of the past late spring. The outlook for the regular handling of Canadian traffic is most encouraging; the Canadians are now busy getting their sets in shape, and we expect to see al] our hopes for international relaying realized this coming winter. M

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October, 1920 Tre ODERATING DEPARTMENT ~ J. O. SMITH Rockville Centre, L. I. TRAFFIC MANAGER S this is being written the turning A point in amateur radio has been reached and the great increase in activity incident to the coming of cooler weather has begun. The past summer marked a new era in our affairs. Never before had we consist- ently tried summer operation, and in the effort to maintain communication through strays and summer absorption many of our stations were increased to an efficiency which would not otherwise have been ob- tained. Many new DX sparks are heard on the air, as a result of this same summer persistency. The reports show that in every territory strays are decreasing and interest is higher than ever before. Our organization is in excellent condition and we are well equipped as we now enter what will doubt- less be the greatest winter Amateur Ra- dio has ever known. The reports in detatil follow: NEW ENGLAND DIVISION Guy R. Entwistle, Manager Two new assignments have been made in this division. Philip F. Robinson, 149 Hollis Avenue, Braintree, Mass., has been appointed Assistant Division Manager and Leon G. Pollard of 194 South Willard Street, Burlington, Vt., has been appointed District Superintendent of Northern Ver- mont. 1CK is well known in the first dis- trict as an efficient relay man, being an important link in the trunk line through New England. Pollard undertakes a real proposition in developing virgin territory im his section. He will also have the Canadian situation to handle. He reports the University of Vermont as ready to help out with relay work this Fall. Below is a reorganization outline of the division: Manager, G. R. Entwistle, 18 Boylston Street, Boston, Mass., 1AL. Asst. D. M., Northern Section. H. W. Castner, 15 Temple Street, Portland, Maine, 1UQ. D. &., D. F. Alexander, 209 Elm Street, Bangor, Maine, 1BK. D. S., A. Ralph Tabbot, 10A Bar Har- bor, Me. QsT D. S., Dartmouth Wireless Club, Han- over, N. H., 1YB. D. S., Leon G. Pollard, 194 South Wil- lard Street, Burlington, Vt. This section adjoins Canada and will look after connections with our Canadian brothers. Assistant District Manager, Philip F. Robinson, 149 Hollis Avenue, Braintree, Mass., 1CK. D. S., Henry R. McLean, 342 Union Ave- nue, Laconia, N. H., 1CM. D. S., Lee A. Bates, 8 Moen Street, Wor- cester, Mass., 1GY. D. S., Wilbur H. Hardy, 776 Hale Street, Beverly Farms, Mass., 1BH. City Manager, Lester Pulley, 33 Porter Street, Melrose, Mass., 1DR. This section, known as the Eastern sec- tion, has the greatest density of amateurs in the district. Includes lower N. H., Eastern Mass. and Rhode Island. Assistant Division Manager, Donald Mix, 40 Stearns Street, Bristol, Conn., 1TS. D. S., Harold C. Bowen, 168 Belmont Street, Fall River, Mass., 1AK. D. S., Homer E. Nichols, 513 Pequon- nock Street, Bridgeport, Conn., 1BM. This section includes Western Mass., Conn., and lower Vermont. Connections to the second district trunk line will be arranged through this section, which will be known as the Western section. Prospective relay men will pick out their nearest District Superintendent and inform him of their intentions if they wish assign- ments as official relay stations. There will be many gatherings of ama- teur wireless men this coming season. To the chairman of the committees on arrang- ing speakers for these meetings, the writer would like to suggest the following. Why not have these meetings on Saturday even- ing as far as possible. This will give speak- ers coming from out-of-town a chance to accommodate these clubs without inter- fering with their regular work which must still be done since greenbacks have long ago replaced clamshells for money. Relay officials are glad to come and contribute whatever little they may to the entertain- ment of the evening. It is much better to be able to lie in bed the morning after.

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Din QST October, 1920 has started the ball roll- On the 15th of Sep- W. Castner, A.D.M., ar- essful meeting at which inent radio men were Inspector, H. C. Gawler, ram Percy Maxim. 1UQ er, the date to be an- Bates of Worcester will :1y men of New England at Watch other columns of 1 tails. Let’s all go and that radio matters are ection during August. naally fierce QRN, and s are the reason. on the map in the per- Lean, who has QSO-ed also is coming strong Learned, who is equipped C-W set and works 1AW of South Manchester, pects his C-W set going S. District Superintendent ed a counterpoise ground tage amplifier. 1TS has BBL, Mr. David Moore of , has been appointed an increased activity in nticipates even greater Winter. 1FV, Rahma ng down the key at pres- success. (We sincerely nd this properly). 1FB, the DX. I have ap- Tabbot, 10A, as D. S. District. he expects to be heard 500 cycle set by Sept. tuff has been holding up 1 some of the new C-W fine. 2FS comes in QSA. LHA, Lloyd Greene, of heard occasionally on New Bedford is heard up 1LHAA down the Cape is h unlimited power supply i and a seasoned fist he his message hook clear. r it pass it to LHAA. He f those new Grebe gaps, early with Ponzi). His a duplicate of 1AW—a more wires. Got 2000 ind 5000 feet in counter- Expects to do some work | say so. 1IHAA has been n’s Harbor. )ANOKE DIVISION lr. Gravely, Manager ip the activities over the past month, there has been a decided curtailing in active operation, but I learn, from many sources, that great preparations are being made for the Fall and Winter months. New stations will be budding forth, and marked improvements will be noted in the old stations. Also, con- tinuous wave sets are beginning to make themselves heard here and there, which shows that the fellows are busy, and are ever working for increased efficiency in their stations. The QSS tests in this division were a complete failure, due, mainly, to the lack of recording stations. The transmitting stations were heard, and their sparks went out on normal radiation, but reports were so few that the data isn’t worth reporting. Mr. Groves, Fading Analyist for the Divis- ion, will cover the ground in his report to QST, so I shal] refrain from making fur- ther comments. It is with a great deal of satisfaction that I am able to report the organization of North Carolina, which is under way. Mr. Bunker, District Superintendent, is working hard to open up routes, in short jumps, from Danville to Atlanta, in con- junction with the other District Superin- tendents. He is also working on the East- ern and Western Routes, and is meeting with a great deal of success. We are now assured of a good station at New Bern, N. C., and another at Wilming- ton, so it seems that the coast line, from Norfolk on down, is an assured fact. Unless it becomes necessary to change plans, the main Southern Route, starting at Washington, will be as follows; Wash- ington, Fredericksburg, Richmond, Lynch- burg, Danville, Greensboro, Charlotte, and thence to the South, with alternative, through Lynchburg (or Roanoke), Wins- ton, Greensboro and Charlotte. I have had letters from Mr. Rothlinger of Wilmington, and Mr. Parker of New Bern, and they both tell me that they will bend their efforts to assist us in the perfec- tion of the organization. These two gen- tlemen may be relied upon, I am sure, to assist in every way possible, and to take part in the activities. Mr. Herndon, Eastern Virginia District Superintendent, writes that activities in his section have been limited, due to the hot weather, and the almost daily thunder storms. He says that information has been received to the effect that the second hump from NAM on 200 meters is caused by re-radiation from the towers, and plans have been drawn up for a complete re-ar- rangement of the antenna system, and that when this has been done, it is hoped that the interference from this course will come to an end—it has long been a seri- ous handicap to relay operations in his vicinity. Report has come from Mr. A. G. Heck,

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October, 1920 Mannington, W. Va., District Superintend- ent, to the effect that radio operations have been at a stand-still in his District during the past two months, but that he expects at least three new first class stations in his vicinity for the fall and winter opera- tions. He also states that 8ZW has been taking a course in VT operation, and ex- pected to have a CW set, and phone, by Sept. ist. (Go to it 8ZW—I hope the Aerial Ammeter will flutter for you). Will the serious amateurs all over West Vir- ginia get in touch with the manager, so as to enable him to work out definite lines. When this is published radio weather will be wonderfully improved, so let’s all pull together, and round out a wonderful winter season. 8BZ will ring in a CW set, too, if he doesn’t burn up all the tubes and meters to be found before he secures one millionth of an ampere radiation. The little bottles have a great deal in them, so friend Stan- ley says, but— it is as hard to get the juice out of them, as it is to get spirits out of an empty corn whisky bottle. DAKOTA DIVISION R. H. Pray, Manager Because of the fact that there was prac- tically no radio work being done in this Division last month there were no reports from the Districts and consequently none was sent in from this Division. But ama- eur radio is beginning to take a new lease of life and there will, no doubt, be a full report next month. The Fading tests in this Division were almost a complete failure, due, I think, to the fact that there was not enough inter- est. Although the transmitting stations were on nearly as scheduled, there were no recording stations and no reports. Of course there were some of the tests during which the static was too bad for recording of any kind but there were also some that were very good for radio work considering the time of vear. But as amateur radio, as practiced by most, is merely a form of recreation we can understand how when a certain WW called for a canoe ride by moon light radio absolutely has no attrac- tion at all. However, I hope that in any future tests this division may at least do as well as our neighboring Divisions. There have been several new appoint- ments in this Division and to give every one a better idea of the men now in office we present the complete list. Division Manager, R. H. Pray, 813 Fifth Avenue, Valley City, No. Dakota, Radio 9ZX. District of Northern Minnesota, J. A. Gielhaug, Baudette, Minn., Supt., Radio 9ZC. City Manager of Duluth, Wm. D. Wag- QsT 25 ner, 123 W. 4th Street, Radio 9EA. District of Southern Minnesota, Boyd Phelps, Care Minnesota Wireless Assn., Room 416 Courthouse, Minneapolis, Supt., Radio 9ZT. District of North Dakota, E. S. Leaven- worth, Ellendale, No. Dakota, Supt., Radio 9WU. City Manager of Fargo, Bert Wick, 207 Broadway, Fargo, No. Dakota, Radio 9AEJ. District of South Dakota, Harold Larson, Viborg, South Dakota, Supt., Radio 9KG. Mr. Boyd Phelps is also acting as As- sistant Division Manager until October 15. There is a determined effort being made to get Trunk Line A in shape to handle traffic regularly. There seems to be an outline for the route in working order at present, which is at least enough to start with and can be filled in as stations ap- pear. The station of Mr. Bridges in Super- ior being the connection with the Central Division, it would run to 9ZC, 9ZX, and connect with the Northwestern Division through 7IM, the station of Mr. R. J. Simms at Billings, Montana. The relays as stated are rather long, being 225 miles from 9ZC to 9ZX, and approximately 600 miles to 71M, but all of the stations in the order named have been working together through very bad strays during the month of Aug- ust so that they should be able to handle traffic without difficulty with the coming of cooler weather. If 7IM gets out to the west as well as he does to the east trunk Line A seems sure of success. Work on trunk line G. from North Dakota to Hous- ton, Texas, will begin as soon as there are enough stations to make it seem feasible. It is hoped that this route can be extended to Winnipeg at an early date. Mr. J. A. Gjelhaug, 9ZC, Superintend- ent of the Northern Minnesota District re- ports increased activity in his territory and prospects of stations to fill in the trunk line early in the fall. There is another Winnipeg station being constructed, call 4AJ, which promises to be able to handle the relaying in that territory. Mr. Larson, 9KG, Superintendent of South Dakota reports very little doing ex- cept in Sioux Falls. Mr. Boyd Phelps, Supervisor of Summer Relay, and Superintendent of the Southern Minnesota District, has been working very hard at routes from the Twin Cities. but owing to the fact that the amateurs in the Division have not had any interest in the summer work he has been unable to form any permanent routes so far. Now that Duluth, Minn., the radio conditions are improving it may be possible to get more results, so will all the members of the A.R.R.L. and any ama- teurs who are interested please write Mr. Phelps, in care of the Minnesota Wireless Assn., 416 Courthouse, Minneapolis.

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26 QsT October, 1920 s monthly reports has been wear themselves out in due course of time. work division which includes’ All through the summer there have not all n f carried out will prove been more than two days a week on an aver- a meal h the relaying and other be put way above stand- ard ; of this plan depends ir ndividual as unless every- each month the data gather t be sufficient to obtain Each member should send officer of his territory, nager, Assistant District District Superintendent 12th of the month. This | activities and observa- radio during the past montl f stations REGULARLY The reason for this is that list of stations worked possible to make use of it 1 and completing routes. one sé port The |! tions heard regularly is asked it if any two stations are hearir ther regularly but never comn would be possible to ar- range e for these stations and thus h utes. PLEASE, EVERY ONE }? nd send in your report not lat TWELFTH OF EACH MONT Now has started and the many vacat outside of radio have ende d that all station owners will District Superintendents about 1 and what they will or hope t ying. Do not think that your big enough to be con- sidered s as the Manager has worked over 100 miles distant which wv r Ford spark coil units and six vol batteries for transmitters, and th is still being done regu- larly. write your District Super- intend: If you are in doubt as to wh you are in write to the Divisi I NORTHWESTERN DIVISION Roy z Mi m ford, Acting Manager Eith« ter relay season begins in August no such a thing as sea- son tivities en the Pacific Coast unanimous verdict of all wh tened in consistently for the last In th estern Division we notice a mark ution of static; but the number tations is far below the normal le of hours of solid grind- ing stat few unsuccessful attempts at long work seem to dishearten many * to such an extent that he leave rial grounded for days at a time this noise and bluff of old man QR) only oceasional outbursts, as of llable fits of anger which age when the static did not slack up a bit some time durirz the night. The only re- quirement, then, for summer long distance work is for two DX men to be on the job at that time. During the month of August some of the hottest days of the year were followed by wonderful nights when signals pounded in with winter-like intensity and their re- ception was marred only by more or less intermittent static. In fact on the very hottest day of the year for Portland and vicinity the first relay traffic for months was handled with Los Angeles direct. From 7CU at Vancouver, Wash., commu- nication has been maintained with Los Angeles direct two or three times a week during the entire month of August. A.R. R.L. traffic has been handled in both direc- tions. Great credit is due the Los Ange- les stations for they are bothered a great deal more with static than we who are far- ther north. Not only Los Angeles but San Francisco, and Santa Ana and Long Beach, all farther south, have been worked from here; and in connecting with San Diego the results were surprisingly successful for the time of the year. In Portland, Ore., preparations are well under way for any amount of A.R.R.L. work this winter. New stations are ap- pearing and most of the old gang of last winter are on the job regularly. We are glad to hear the spark of 7BR again. He is sure to do his share of long distance work. 7ZI of ex-7DK fame has his new set ready for business and is making him- self heard in all directions. He has re- cently connected with California stations 500 miles away and soon expects to break his records of last season. Most of the traffic is at present handled by 7DS, 7DP, and 7BP, all of whom work north to Seattle and both 7DP and 7BP work Ukiah, Calif., successfully. 7CR has recently made some satisfactory tests with the forestry service stations on Mount Hood. In Seattle the relayers are all looking forward to the QRN-less season this winter and are planning on more extensive partici- pation in A.R.R.L. work. The same is true of Tacoma and Lacey, Wash. In this locality we have four stations which are to be especially commended on their consist- ent performance this summer, 7AD, 7BK, 7CE, and 7YS. And lest we forget their good work in the coming of the winter sea- son and the multiplicity of relay stations, let me say that but for the work of these faithful few relay work in their locality would have been practically dead. We are highly pleased with our first attempt to stick to the job all summer.

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October, 1920 Amateurs in this division were startled to hear the spark of 5BR of Vancouver, B C., which is the first Canadian station, so far as we know, that has connected with any of our “sevens”. Mr. Wood is back at 6KL Oakland, California now. While at 5BR he worked stations in Seattle, Port- land, and Vancouver, Wash. He reports increasing activity among the Canadian amateurs. Olfan De Guire, 7CW, District Superin- tendent, Silverton, Oregon, has been doing excellent work this summer. He handles any number of messages from Seattle south and keeps the business moving with but little delay. In Everett, Washington, we have a new spark 7FV which is QSA here. We are sure he will make a good relay station as soon as he is on the job regularly Our Division Manager, Mr. Hertz, bet- ter known as 7ZB to all who have heard his spark, has been away in Alaska with lenty of time to make plans for the com- ng season. He is back in our midst again ow, and we will be glad to see him on act- ive duty for the A.R.R L. ' l ’ In the Eastern section of this Division R. Earl Dawes, Box 663, Bozeman, Mon- tana, has taken right hold of the work. With his assistants he is planning to put Montana on the map this winter and will start in as soon as the QRN subsides. The outlook for fall and winter is very good The following have been appointed Dis- trict Superintendents: Mr. L. L. Stanley, 7DJ, 320 State Street, Helena, Mont.; Mr. Grey, 7FL, care Grey Machine Shops, Butte, Mont.; Mr. Winfred Slausen, 7ZG, Bear- creek, Mont-; and Mr. Everett Cutting, at Bozeman, Mont., will assist Mr. Dawes in his work. Currie N. Teed, District Superintend- ent, Kuna, Idaho, reports that little activ- ity has been shown by local amateurs dur- ing the past month. Dry hot weather and unusually frequent electrical storms have caused a great deal of trouble, static often for days at a time being audible anywhere n the room. Considering the conditions in his locality one must admit that he is doing mighty good summer work and his efforts are appreciated. PACIFIC DIVISION A. E. Bessey, Manager The radio situation on the Coast is very favorable for the summer~«time. Traffic has been going through in great shape. Never in the history of radio has traffic been handled in the summer time as this year. All the stations have been putting in high grade apparatus and amplifiers and getting their sets tuned so that they are getting through on LD work in fine shape. In my report for the Bay District, will QsT say that we have many good long distance amateurs who are reaching out in handling traffic. At the present time, 6BN seems to be doing the best work both North and South. He is handling messages direct with San Diego 6JI. His best station to work with in Los Angeles seems to be 6KP, 6EX, and 6EP. Many others are doing good long distance work. It has been impossible for us to get through to the East during the summer owing to the fact that 6ZA is on a boat and his station is closed for the summer. The only routing there through the South, which is rather unsatisfactory, is tarough Arizona, but there are many new stations opening up in Arizona and one new special tation at Yuma, so that we feel sure tha this winter we will be able to work through the East without any trouble We have the promise of a good station to be set up in El Centro, California, within a short time which will help in bridging the gap to Arizona. It is to be hoped the San Diego district wil] be of valuable assist- ance in handling traffic to the East. At present, San Diego is being fitted to handle relay traffic at 6EN, 61Y, 61Z and 6JI. Mr. Milton Jackson has been appoint- ed District Superintendent for San Diego Fresno is showing great interest in radio at the present time and although their con- ditions seem to be rather peculiar as they seem to be in a pocket and it was rather hard for them to get out, I think they can work up the valley to Sacramento; also to Los Angeles and San Diego. Their sets are getting more efficient all the time and feel sure by winter they will be doing good work. Routing to Los Angeles from the bay district or North, can go through either 6BN, 6EP, 6EX, 6FS or 6UM. All can go through to the South. 6BR at the present time is out of commission on account of installing a new transmitter set and will be working soon under a special license, calling wave 200, working wave 375 meters, 150 meters for local work. Would appreciate very much if all sta- tions that feel they can do LD work would drop a card to 6BR as we wish to get our traffic stations lined up for this winter. WEST GULF DIVISION Frank M. Corlett, Manager Reports from the various Superintend- ents throughhout the Division show that in- terest and activities that have been lacking to some extent are again making their appearance. This is indeed encouraging. District Superintendent W. H. Tilley, 5ZU, Austin, Texas, makes the most in- teresting report for this month that has been made since he assumed control of that District. Austin will be well represented

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EJ and two or three more ‘construction. 5ZU is now n ylight schedule every hour Nettleton, of Eagle Pass, some extensive repairs will be with us with a n which will open up er. He is an old timer in ving been at it for years. will be ready for day- liately providing he does 1\y station at Del Rio too of our members were of the Government sta- e better off. of New Braunfels is now ys he will be glad to help way to San Antonio and strength of his signals be assured of a real relay vn. San Antonio will be ve are promised a depend- about the middle of Sep- he effort of one of the n the war. s, 5AO, Houston, Texas, ted Assistant District Sup- ussigned the HOUSTON, rORY. His report is in- 1 the splendid co-opera- iston Chronicle and the ib fine results are being erritory. The paper is and has a regular Radio lay devoted to the Hous- munications from out-of- ire invited. So far many been heard from and rs helped through the the Houston Club mem- Worthington is City Man- his call being 5ZV. The 1 membership of 60. Whitworth, of Freeport, I . great improvements in his have a reliable station ind most any kind of a ng made to get someone n Beaumont to enter the no results. the following stations are iy work: 5AO, 5ZV, 5ZT, HE, 5ZW. 5ZW and 5AO 1 daylight schedule twice - for which they deserve The Radio Inspector is due and many are gettting examinations. Station, Texas, is erecting the A.R.R.L. is assured there soon. From the ered with 30 foot antennae re is no telling what they om L. White, 5AP, District ~ QsT October, 1920 Superintendent of the Northern Texas Dis- trict, has returned from his vacation and in less than an hour or so was heard in the air again. Due to the intensity of atmos- pheric disturbances very little relay work is being done at night but at intervals we hear some good fellow-member tussling with old man static trying to hand a few messages over in short jumps and numer- ous “QTA’s” are heard. The Assistant District Superintendents are taking ad- vantage of the occasion and are putting over some commendable organization work. Among those deserving mention are Henry M. Harris of the Waco, Texas, Territory, and Martin, 5IF, of the Amarillo, Texas, Territory. No doubt 5IF will relieve the now congested condition westward and will grow into prominence as 5ZA has on our way westward; it will also reduce the long jump somewhat. A City Manager is to be appointed for Amarillo proper, which looks good toward minimizing interference. Keep the good work up, Martin, we are with you. Harris at Waco has been assigned the call 5GJ. He has assisted in getting a station underway at Stamford, Texas, which will be right in line west from Waco and should make a good relay point. If someone would just come forward with a relay station at Sweetwater or Lubbock, the route west to Roswell would be a cer- tainty, static or no static. Q9RY is heard at Amarillo quite frequently and 9BW and 9LR have been heard often in Dallas and vicinity lately. The district of Oklahoma again begins to look promising. Mr. Lawin G. Dill, 234 South Broadway, Oklahoma City, was in Dallas recently and called on the Division Manager. Mr. Dill stated that he would have a 1KW in first class working order shortly. Mr. Walton of Oklahoma City will also have his station working regular, Mr. Dill stated. This will give the A.R R.L. two stations in the central part of Okla- homa. With 5BT at Blackwell and 5DO of Perry, 5BM at Muskogee, and several other stations that we know of, Oklahoma should be with us in the relay game very shortly. The Division Manager is working under a handicap regarding Oklahoma. The Okla- homa stations have never been received at headquarters with any great signal strength and for this reason the District Manager has not been able to determine which sta- tion owner would make the best District Superintendent for Oklahoma. I am going to put it up to the Oklahoma station own- ers to suggest which man they think would make the ideal District Superintendent for Oklahoma. In making your suggestions remember it is the policy of the League to select only those which are best fitted for relay work from the point of view of radio equipment, reliability of operation,

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October, 1920 QST 29 and the time he is willing to devote to re- lay work. Oklahoma should by all means have a District Superintendent to take charge of the relay activities and assist in getting Trunk Line “F’” working from Dal- las to the Northern boundary of this Division. Let every amateur in Oklahoma offer a suggestion. ONTARIO DIVISION A. H. K. Russell, Manager August has been marked by a profound deadness in amateur wireless, due to the holidays and to the fact that a great num- ber of amateurs are on commercial work on the Lakes. However, with the coming of the fal] wireless should again come into its own, and be bigger and better than ever. The report for August must be of neces- sity brief, for the District Superintendents have omitted to make reports for the month, probably due to lack of material. However, the Superintendent in Western Ontario, Mr. Carter, advises that prospects ‘ex never looked better for a successful season in his district and the same information comes from the secretary of the Club oper- ating in affiliation with the A.R.R.L. in Northern Ontario. So far as Toronto district is concerned it is hoped that there will be at least one and probably two medium powered C.W. transmitters in operation, with which it is hoped to establish steady C.W. communi- cation with “8” stations. In any case a reliable outlet for Ontario traffic for the winter should be available through Niagara Falls, N. Y ATLANTIC DIVISION Chas. A. Service, Jr., Manager - The past month, being a vacation month, is probably the most inactive month of the year from a radio standpoint, in spite of the fact that the actual work done by those who have remained at home has been greater than ever before. Stations that in former years were only heard during the winter months have been heard frequently throughout the summer season, and with the advances that will no doubt be made during the coming winter season it is be- lieved that more actual relay work will be accomplished than ever before. The report of the Traffic Assistant for the Central Pennsylvania District, Mr. Her- bert M. Walleze, who is acting as District Superintendent during the continued ab- sence from home of Mr. Cawley, shows that ue conditions in that section of the State are dull, but that there is considerable activity in remodelling and improving stations. Among others that are improving their sta- tions is 3ABD at Danville, Pa., which is one of the stations that we are depending upon this coming winter to fill in on the gap between Reading and Milton on Trunk Line B. Unfortunately the Eastern Pennsylvania District is without the assistance of a Dis- trict Superintendent since the resignation of Mr. Ferris, but the question of filling this vacancy will receive early attention. We had hoped by this time to have received definite information from Mr. C. M. Jack- son, of Pottsville, that his transmitting set was in operating condition, as a station at this point could be of considerable aid in bridging the gap between Reading and Dan- ville or Milton. The last information re- ceived from Mr. Jackson in April last in- dicated that he was about to install his transmitter, but since nothing further has been heard from him by the former District Superintendent. Station 3HJ at Haver- ford, Penna., has been doing good relay work in this District, and can probably be counted upon in the future. Station 3ZS again is in operation, after some necessary repairs to the spark gap, but so far the set has not been properly adjusted to work on the lower wave length of 200 meters, but it is hoped that this difficulty will be over- come shortly. Mr. C. S. Horn, Superintendent for Delaware, has returned from a commercial trip to Holland and Belgium. He states that he has not yet been able to get his station in operation at Rehoboth as he ex- pected, and, as the summer is about over, it is not likely that he wili accomplish much at this point this season. He states that he has information which leads him to be- lieve that a new station will be set up somewhere half way between Wilmington and Baltimore, and that he will endeavor to give what assistance he can in making this proposed station an efficient one for re- lay work between Wilmington and Balti- more. Station 30B at Wilmington, Del., has been doing some good work during the summer, and has extended his range to some distance, which is promising for the coming season. Mr. Duvall, Superintendent, Eastern Maryland, reports that he has been in touch with Washington station owners, and that in conjunction with them every effort will be made to establish reliable communication between Baltimore and Washington in the near future. The vacancy in the office of District Superintendent for the District of Columbia will no doubt be filled within a short time, as this matter is now being given attention, and when this is accom- plished better results can be looked for. Mr. Duvall gives in detail in his report data relative to Baltimore and Washington stations, and in addition to this survey Mr. Duvall is sending out a questionnaire to

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80 QST that vicinity with a view lata possible on the stations. Taken as a M s; report indicates re- lis part, and we have rty co-operation on the Baltimore and Wash- lificulty of communica- may be overcome in the certainly be a satis- e accomplished. WEST DIVISION Benson, Manager lanager is glad to report that n both Relay and League wor ng shown by all District Supe ind Assistants. Several Dist endents have recently re- tur r vacation and are at it hat lined up. Distant sta- » roll in like old times, ng colder, and every- fact that a big season is O), District Superintend- ent 1s appointed Mr. J. Gie- Si nt Place, Jefferson City, Mo \ssistant District Super- inter Mo. This will prove a handling traffic to Kan- ( Louis. G U), has just returned from the re he had the pleasure of 1 i Bros., 6EA. Mr. Tur- ner ite a good reliable sta- tior ' ere he states there are He says 9ZF has sold his sta to quit the game; this leave no long distance station De J. G , District Superintendent, Faste , reports all his routes workir and several new ones 10 He has just returned fr -h the state and reports nt the following towns: Nort tand York. Any stations n th report to the District _ P. A 9JA), District Superin- nde given up CW and is get- ting set in trim. Mr. Stover want located in the extreme wester f Iowa to kindly get in ouct once, H. I JEL), District Superin- tender has recently returned from } and is unable to give his report r this issue. However, he wishes ns in his respective terri- tory .t ate with him regarding appoint several western routes Lnaroug e October, 1920 BULB OSCILLATORS FOR RADIO TRANSMISSION (Continued from page 8) curves. From these waves the losses and output of the oscillator may be determined Thus by assuming various values for the potentials and plotting first the appropriate characteristic curves and then the waves, the behavior of an oscillator under all possible adjustments and loads may be ex- amined. Usually such a process is far too laborious for a general numerical investi- gation, but is useful for a qualitative study. As a matter of fact, the curves of Fig. 6, 7 and 8 have been so chosen as to repre- sent underload, normal load and overload, respectively, of a bulb oscillator with fixed supply voltage E,, fixed grid bias re- sistance R., and fixed ratio n of alternating plate voltage to alternating grid voltage. With the light-load conditions of Fig. 6 (corresponding to a low antenna resistance in Fig. 9 and 10), the alternating and direct components of plate current are relatively small, while the alternating components of the potentials are high. The minimum of plate potential is then slightly negative, causing all of the space current to flow to the grid for an interval and giving a sharp dip to zero in the plate current curve. This does not harm the bulb, but the out- put is much below that attainable from the bulb. With the normal-load conditions of Fig. 7, the potentials vary over narrower ranges and never permit an excessive grid current; so the plate current has little or no dip and is higher than before. With the heavy-load conditions of Fig. 8 (cor- responding to a high antenna resistance in Fig. 9 and 10), the potentials vary over still narrower ranges and the minimum plate potential is much higher. This great- ly increases the loss at the plate and will overheat the bulb, though the power out- put is not greatly different from that in Fig. 7. The direct voltage (bias) and the alter- nating voltage (excitation) of the grid circuit are chosen with a view to giving high output and high efficiency, but are not highly critical in adjustment. The best ratio (n) of alternating plate voltage to alternating grid voltage has sometimes been considered to be equal to half the ampli- fication constant of the bulb, this cor- sponding to an external (load) resistance in the plate circuit equal to the internal resistance*. But considerably higher grid voltages may be desirable On the whole, the proper load, bias voltage, and excitation voltage of a bulb oscillator, as well as the heating current and the plate generator vlotage, are best determined by direct test. These quanti- ties are all constants of the bulb and do (Continued on page 37) =

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October, 1920 r / re, oD #r a—— take pleasure in announcing the affiliation of the following W — which was completed at the last meeting of our Board of Direction: Plattsburgh Wireless Club, Plattsburgh, N. Y. Radio Club of Paterson High School, Paterson, St. Louis Radio Assn., St. Louis, Connecticut Valley Radio Club, Springfield, Mass. Penn Yan, N. Y. Erie, Pa. Troy, BM Ua Rochester, N. Y. Waterville, Me. N. J. Mo. Yates Radio Club, The Summit Radio Club, Trov YMCA Radio Club, tochester Radio Club, Central Maine Radio Club, Pomona Radio Assn., Pomona, Calif. Radio Club of Syracuse, Syracuse, N. Y. Crescent Radio Club, Clearfield, Pa Bethlehem Radio Assn., Bethlehem, Pa. Marietta Radio League, Marietta, Ohio. Miami Radio Club, Miami, Fla. Radio Club of Tacoma, Tacoma, Wash. Columbus Radio Club, Columbus, Ohio. Baltimore Radio Assn.., Baltimore, Md. Ann Arbor Radio Assn., Ann Arbor, Mich. Radio Club of Burlington, Buriineton, Iowa. Calesburg Radio Assn., Galesburg, II! Radio Club of Washington, Washineton, D. C. Radio Research Club of New York City. New York, N. Y Wireless Assn. of Atlantic City, Atlantic City, N. J. Southern ilifornia Radio Assn, Los Angeles, Calif Radio Club of Glen Ridge, Glen Ridge, N. J. Essex County Radio Assn, Salem, Mass. Cass Radio Club. Detroit, Mich. Framingham Radio Club. Framingham, Mass. Oshkosh Radio Club, Oshkosh, Wis. Uteh Radio Assn., Salt Lake City, Utah. Radio Engineering Society, Pittsburgh, Pa. Eastern Ohio & Western Penna. Radio Amateurs Assn, Newcastle, Pa. Sunset Radio Club. San Diego, Calif. Springfield Radio Assn.. Springfield, Mass. Central Michigan Wireless Assn.. Lansing, Mich. The number of organizations now affili- 85—all of ated with the A.R.R.L. totals TH THE AFFILIATED CLUBS: L@ ¥ “give Wir. ad Radio Club AFFitiareo j wit THE ey tT AR'R'L: them live ‘wires. This number includes most of the radio associations of promin- ence, and marks our progress toward the formation of a network of local organiza- tions which will bind us all close together in matters which concern Amateur Radio. The A.R.R.L. Secretary will be glad to hear from clubs who think as the A.R R.L: does on amateur affairs. THE CHICAGO CONVENTION The greatest meeting of amateurs ever held occurred in the convention of the A.R.R.L. Central Division at Chicago, Sept. 2d, 3d, and 4th. It was great in many ways. It was marked by enthusiasm of the highest pitch; the interest and value of the sessions were the best ever; and it was the first time in our history that ama- teurs from many miles have gathered for a three-day discussion of their affairs. As most of us know, there is in existence in Chicago an organization known as the Chicago Executive Council, comprised of » Edgewater Beach Hotel, the officers of the three prominent clubs there— the Ravenswood, the South Side, and the Progressive, all affiliated with the A.R.R.L.—with the Chicago City Manager, Mr. F. H. Schnell, as Chairman. This board meets whenever desirable, and ad- ministers all amateur affairs in the city. The co-operation is wonderful, and they are doing great things in the reduction of QRM, etc. It was this organization which, at the instigation of Mr. Mathews, the Division Manager, arranged and engineered the convention. They did a most splendid Scene of the Convention.

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job it thar cal Cer there The on She activit end of was ti thruou pep of Visitor out the us met we ha tinuou matior for I This the Ce able M the k before cussed it was teurs Presid: cussed point, ities next, legislati operati! Mr. F on the A.R.R.1 of co and in t ency lined of fun held, ir QsT cannot better describe . that it was done in typi- ision style—than which re thanwhicher. Edgewater Beach Hotel, id, was the scene of the s located on the northern el grounds, and of course f interest. The weather il, and contributed to the On the first day the tered at 9ZN, and thru- next as well, many of t time men whose sparks for long. It was a con- greetings and the for- riendships—absolutely F.B. the first meeting was Cat room of the hotel. eral business meeting of sion, presided over by the vs, and “Co-operation” was It is probable that never subject so thoroly dis- aspects—and very good yur very existence as ama- yn this. Mr. Maxim, our the first speaker, and dis- rs from the national stand- yperation in all our activ- B. West (old 8AEZ) was sed the probable trend of the desirability of co- the government branches. ton, 9ZJ, also spoke briefly ibject. Mr. K. B. Warner, etary, spoke on a few phases n, particularly with our QST rovement of operating effici- schnell, City Manager, out- cago Plan” and its method and was followed by Radio October, 1920 Inspector C. C. Kolster, incidentally Chairman of the Trial Board of the Ex- ecutive Council, who discussed the relations of his office to the amateurs and compli- mented the local men on their methods. Mr. W..L. Holst, President of the Ravens- wood Radio Assn, described the formation and growth of that club, and the results that are now being secured by all the local clubs thru co-operation. The forenoon of the second day most of the visitors journeyed by auto to NAJ, Great Lakes, where they inspected the radio training school, ate navy chow for lunch, and otherwise enjoyed themselves, thru the courtesy of Mr. West, Lt. Comdr. McCauley, and Lt. Arney. An impromptu indoor baseball game was played on the THE CHICAGO EXECUTIVE COUNCIL to whom credit for the succes; of the Convention is due. First row, left to right: F. H. Schnell, Chicago City Manager; C. c Kolster, Radio Inspector 9th District Department of Commerce; R. H. G. Mathews, Central Division Manager. Second row, left to right: G. A. FitzSimons, Traffic Assistant to the Division Manager; S. Wnorski, Ravenswood Radio Association; W. Holst, President Ravenswood Radio Association; M. Romberg, President South Side Radio Association; J. Novak, South Side Radio Association; B. Stolte, South Side Radio Associa- tion; J. Sholtes, Ravenswood Radio Association; N. Wunderlich, Ravens- wood Radio Association. grounds adjoining 9ZN, in the afternoon, and in the evening a technical meeting was held at the hotel. This was a REGULAR hamfest, and like all the other meetings, was 1:30 a.m. breaking up, only this one was more so. Mr. Maxim gave an ex- tremely interesting talk on the sound values of various “noises’—pointing out the re- quirements in radio development to pro- duce the most sound from a given amount of energy. Mr. H. E. Rawson had on ex- hibit a variety of British apparatus, in- cluding a 6-stage radio frequency amplifier and some power bulbs, and described them and his recent trip to England in most en- tertaining fashion. Ye Ed urged the adoption of radio-frequency amplification, better quenching in our rotary gaps, and unburdened himself on the subject of C.W. Mr. Montraville Wood, of Berwyn, II1., in- ventor of the “submarine ear’, a device for the auto-steering of torpedoes by sound waves emanating from the enemy ship, made an interesting demonstration of his device. A lamp was caused to light when

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October, 1920 The Banquet, on the night of Sept. 4. certain words were spoken near the sen- sitive diaphragm, yet it was insensible to other words. It was also caused to oper- ate by a part of the audience clapping hands in unison, and a startling conclusion was reached when Mr. Wood switched in a smal] “cannon” which exploded with a deafening roar the next time the hand- clapping occurred. After a ten minute in- termission, Mr. L. C. Young spoke on the work at NSF, using a C.W. transmitter and a multiple-tuned antenna; Mr. J. H. Miller delivered a paper on radio measur- ing instruments and their uses, particular- ly pointing out the superiority of the thermo-couple type of meter; Mr. T. B. Lambert, of Lambert & Associates, de- scribed an early invention for obtaining secrecy in transmission by rapidly chang- ing wave length, with a synchronized re- ceiver; Mr. F. S. McCullough, of the Glenn L. Martin Company, displayed his new 75-watt tube and described some of the work in tube transmission done at GMA, now 8ZC; and Mr. M. B. West, pioneer in amateur spark work, gave a valuable talk on the design of amateur transmitters, particularly the steps neces- sary to obtain a lower decrement in spark sets to comply with the probable require- ments of new legislation. Those who were sufficiently active to get up on time the next morning, made an auto trip over the boulevard system of Chicago, stopping to inspect a few ama- teur stations, and in the afternoon the radio field events were staged in the grounds surrounding 9ZN. There were The Gang, photographed while visiting Great Lakes.

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QST October, 1920 e out and correct, and in which the contest- s on a small hand loop stal detector and phones dollars worth of appar- 1s prizes to the winners. f the last day occurred ill, the banquet, where reigned supreme. It was ‘ul Colonial Room of the Most of the local men with them, and “bright ‘er fair women and brave brilliant assembly of the the central states, and ed by everyone. Music es provided the necessary and made anything like ble. Brief remarks were rs. Maxim, Holst, and presenting for its first he Sacred and Venerable vas peculiarly appropri- first occur in the home ld Man. Suggestions as employing the Wouff for, but the best that vas to “hook ’er to yer hole Tresco outfit was nteresting things oc- banquet that we must tion short or there will se in this QST. D. F. jazz hound, gave a s art by accompanying impromptu xylophone blers with various levels lus an empty cigar box Prominent amateurs dentified by call letters Old Man was received rer, commenting on the Old Man could, and that he could not be tionnaire, the craziest be imagined, and repro- roduct of the disordered Novak, was filled out by to be awarded the best cursory inspection of 1 that one of these was the others as to merit Prize, and Mr. H. H. ally presented with one Co. Tesla Coil in re- achievement. The com- ured all the antique shops de Condenser, bit none QRM contests, the guests ked up on a small aerial ru a loud-speaker, were are being distributed to Council has commenced f a monthly sheet en- eak”, and the first issue vention Bulletin and con- tained all the news. It is a live, peppy sheet, and will do much good. It was a wonderful meeting—one which did much for the cause of Amateur Radio. It stands as the high water mark of ama- teur achievement to date, and the next crowd to improve upon it will have SOME job on their hands. We make our best bow to the Chicago Executive Council. Too much credit cannot be given the Central Division Manager, the indefatigable Mr. Mathews. He was everywhere at once, seeing that everyone was happy, and at the meetings he proved a most capable Chairman and Toastmaster SIDELIGHTS ON THE CONVENTION The oldest amateur present was Mr. F M. Bookwalter, of Springfield, Ohio, 84 years young; his enthusiasm was the peer of anyone’s. The youngest member at- tending was Mr. J. R Miller, 9CP of Hammond, Ind., aged 14. 9CP has a first- class station, has passed his 20-word test, and is prominent in relaying in the Chicago district. It passed the comprehension of one ama- teur present at the technical session that a priest could be a radio bug. Approach- ing Rev. A. J. Manning, he inquired: “Mister, are you interested in wireless? We'll say 8DA is——rather W. H. Kirwan and the Iowa de'egation were present with bells. On the rear of their car was a large sign with the Davenport slogan: ‘“‘Hook ’er to yer bulb!” Did you see Matty’s bulletin board at 9ZN—a sheet of bakelite only worth about $25. If any of you fellows get a Paragon with some chalked announcement on the inside of the panel about “Grand Banquet to-night’, you’ll know how it happened. Did you meet the representative of the Wooden Audiotron Co.? St. Louis, altho not in the Central Division, was represented by a delegation of about ten men. Yes, Bill was there Now for Novak’s questionaire The questions were as follows: If Marconi wasn’t a Frenchman and yet the in- ventor or or wireless put yes here .but if DeForest invented the Armstrong system draw the symbol of a variable condenser here. . Do the electrons flow from the plate to hem grid? If not how do they flow? From.. If the high voltage on your grid should ro ‘eectibee, put NO here. . and if it should be negative, answer in the negative here.......... If a non-synchronous spark transmitter produces undamped waves, put the symbol for a generator ise nie & Omen and if you think that the polarity of your ground lead is positive, answer in the negative... ~_ > an undamped set a decrement what (Concluded on page 37)

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October, 1920 — am — ’ fd R RADIO STATIONS * ‘ Y. 1HAA, MARION, MASS. Ent: “Who is this guy 1HAA?” Wi tle: lon’t know, sounds vermilya.” With which VN once again our pages Yes, Irving but breaks the Vermilya doesn’t get enough radio working all day the Marion transatlantic statior has to pound brass on 200 1HAA has made a most enviable reputation and is counted one of our trongest eastern stations for the coming winter We rrevtent here several views of his equipment. The aerial is perhaps the most interesting It slanting flat-too, but e 1AW’s it is nearer a fan than a flat-top {wo 100-foot poles, 54 ft. apart, support the upper ends of 20 No. 14 bare coprer wires, which are spaced 2% feet apart acros a eable which in turn is carefully insulated it both ends. These 20 wires re 97 ft. long and terminate on a wooden t der supported by a vy pole set 62 feet back of a line connecting the tv'o main poles. The spac- ing at the bottom spreader is 1 ft., and from there a 19-foot lead-in runs to the et. 1HAA uses a counter- reise ymisisting of 650 vy res covering an aera of 50 ft. wide and 100 ft. long, supported 4 ft. above the ground by 20- inch insulators on each of the four corners, and eorefully insulated from all grass or ground. This at ni ght. seems to us a most excellent arrangement The transmitter comprises a 30,000 volt United Wireless “coffin”, a Grebe synchro- nous rotary (altho this photo shows an old Marconi ship rotary), a “doctored” Clapp-Eastham O.T., and a condenser con- sisting of 36 Marconi jars of .001 mfd. each, in series multiple, giving a capacity of .01 mfd. * . - ~ = ~ a : ard «3 : ’ ccae | | , ; i } 4 ; : : ; ; ; : | | : ; ; } Agee dS } } 4 ' ae | r ' ; } j /

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a ea od October, 1920 This station’s operator is addi- cted to the use of the bug. When you hear a bunch of hash and all you can make out is the “1’’, log it as LHAA—a good call for a Funny-Man. 5ZP NEW ORLEANS (Photo on next page) This station is owned and oper- ated by Hubert E. de Ben, and is located at 1044 City Park Avenue, New Orleans, Louisiana. The sigs of 5ZP have been heard in twenty states. The aerial is an inverted “L” type, 40 feet high and 50 feet long of five number fourteen wires. With the present high grade apparatus used by the aver- age amateur, excellent results can be obtained with a small aerial. The ground consists of galvan- ized wire netting buried six inches in the ground directly beneath the aerial. Connections are also made to the water pipe and several small lengths of pipe driven in the ground. Two regenerative sets are used for receiving. One is used for wave lengths from 170 to 450 consists of a Grebe and the other is employed for a detector. yni hard tube as a The transmitter consists of a Winger nd a 2-step amplifier % KW transformer (only four miles from using the same kind NAT), Grebe rotary spark gap, Dubilier and Klitzen condensers, Thordarson oscil-

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October, 1920 lation transformer, Westinghouse ammeter, etc. The transformer, protective-device, fuseblocks, etc., are under the table. The radiation on 250 meters with a decrement of .10 is 5 amperes. Actual work has been carried on with

THE CHICAGO CONVENTION (Concluded from page 34) this far answer If you think that you are correct that you have NO .and if you believe missed some, put NO here nan If you know that you are as foolish as the bird that wrote this, write NO........ and if not write NO anyway If QST is published in Hartford, Mass., don't r the next question but tell us what the call ans we of Arlington is here... ede If you prefer to have Naval control of radio amateurs, write the word NO and if not, fill in the last question with your initials. Now that you are near the end, go back and write YES in place of the first and third where you have written NO If you don’t know what we mean answer in the affirmative How many licensed amateurs do you think are in GREOGRRT < 26 c-6eceeeve If you are so good that you have gotten all the above answered correctly thereby winning the first second or third prize, do you agree to appropriate dollar for this honor?...... . Write YES. one Mr. C. W. Patch, of 5 Villa St., Dubuque, Iowa, has favored us with a set of eleven photographs which he took at the Convention. We regret that space does not permit us to publish all of them. Anyone desiring prints of these photo- QsT

37 the following stations: NSF, Anacostia, D.C., northeast, 1000 miles. 8EN, Norfolk, Va., northeast, 970 miles. 5ZA, Roswell, N. Mex., west, 950 miles. 9KM, Peoria, Ill., north, 800 miles.

BULB OSCILLATORS (Continued from page 30) not depend on the wave-length or other characteristics of the load. When no data of the oscillating circuit is available, the r.m.s. value of the plate alternating voltage (E,) may be assumed one half of the plete generator voltage (E,.) and the efficiency may be assumed 50%; the bias resistance (R.) and grid alternating voltage (E,) should be made adjustable, the probable values being assumed, using Table II as a guide. *The relation between these resistances is determined wholly by the voltage ratio, (n); for any change in the external plate resistance would be followed by a cor- responding change in the internal re- sistance, the latter not behaving as a con- stant in a_ self-excited oscillator under varying load. (To be continued) graphs, ail of which are very good, can secure them from Mr. Patch at 12 %c each, plus postage.

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$8 QsT October, 1920 Another C.W. Problem Solved By J. O. Smith, 2ZL. f QST not far removed nee contained a story of elopment of amateur C.W. on in which the author, L. Stanley, made several refer he writer. The writer has able to decide whether vere intended as a compli- t but, as long as our friend tal arted something, we might ther chapter. Af | finally succeeded in in- jecti pere or so of C.W. juice, ene! ever the blamed stuff is, na, every Tom, Dick and iple of hundred cousins of their: them, collectively and in- div the greatest possible de- tely informing us, because would like to know, don’t while the C.W. signals were d through QRM, QRN and )’s don’t you know, they h yes, very, very much. indry of their dear hearts, ing. We positively knew “N nly too dingbusted well. Ju ere we were actually doin verybody doubted coul ll the F. A.’s in the radio C.W. transmission on eths was impossible, be- ving so badly that no one end would be able to W friend Stanley, in his ’ suggested that he had radio experts and he would what caused our dinky “Try” was good, because So we started out our- the universal problem of wit gnals on midget wave For our lives, 2FS and the writer We agreed that the swing , hange in wave length or fr mething, but we weren’t I led, however, that in some vay occurred somewhere in the te ind system and we, accord- smission under different ither, to see if we could blam« untenna. We decided that found that on calm nights the re much steadier than on windy when the antenna was himr , presto!, quick, like that, the gt ume to us, that if we could have a stationary antenna, we could avoid changes of capacity, etc., consequently changes of everything else touchin’ on and appertainin’ thereto. The signals would be readable without the receiving operator spraining both wrists in turning knobs, etc., in trying to keep them in. The next day the writer bought a pound of bell wire and some carpet tacks and made a stationary antenna in the attic. Then, when all was set and ready, the writer transmitted to friend Stanley and breathlessly awaited the reply, “Signals absolutely steady, QSA, no swing”’. However, the next time the transmission took place, 2FS reported “your signals swung at first but O.K. toward the last. What did you change?” That was a hard one, as nothing had been changed. The same thing happened occasionally afterward on various periods of transmission and finally the writer got rather hot about it and opened the window of the operating room for air. As he did so, he heard a steam train of the Long Island Railroad disappearing in the dis- tance. Evidently the train had in some way affected those C.W. signals although the railroad is four blocks away. When the next train came along the result was that no swing took place. We were stumped. The the writer recalled a journey he once made in the southwest. The train had been bumping and jolting along over the rails in terrible fashion for two or three hours. All at once it settled down and ran along so smoothly that the writer remarked to the conductor that they must have put in new rails on that particular streatch of track, or something. “Oh, no”, said he “we ran off the rails back there a ways and we are now running on the ties.” Could it be possible that the same thing had happened to that second Long Island train? But no, it finally developed that a heavy freight train would cause enough vibra- tion to shake up the bell-wire antenna and a passenger train wouldn’t. So the next day the indoor antenna was nailed fast for keeps and whether they now run on the rails or ties makes no difference, the signals do not swing any more. And so it came to pass that another great engineering problem was solved and given to a breathless, waiting world—at a cost of sixty-five cents.

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October, 1920 aa The Editor would like to have the address of Mr. Gilbert E. Mears. Bill Woods was telling us about an ama- teur in Wood River, Ill., who operates a 2-inch spark coil and two sections of Amrad quenched gap from the magneto current of his Ford. All he has to do is to crank up the Henry, and he has his own power plant, and can get any note he wants. This takes the platinum gridleak. Have any of our experimenters who have worked with Oudin and Tesla coils ever obtained those slow-moving “balls of fire” which are like ball lightning? Radio Inspector H. C. Gawler, First District, announces that during the school term, September to June, amateurs may appear at the Custom House, Boston, Mass. for examination for amateur oper- ator’s license on any day of the business week except Thursday. Thursday is re- served for examinations for first grade commercial operator’s license. To Sept. 9th 1350 licenses were issued for amateur transmitters in the First District, the last call issued being 1FBV. Spruance, formerly of Mont- will confer a favor upon Lester M. Spangenberg, 25 So. 4th St., Lake View Heights, Paterson, N. J., if he will com- municate with him. Last April Mr. Spruance advised 2ZM that his small phone set had been heard in Montreal, the letter being forwarded to 2ZM thru QST, and Mr. Spangenberg desires further light. Harry J. real, Que., The East Side Y.M.C.A., 153 East 86th St., New York, announce the inauguration of a course in the Theory and Operation of Vacuum Tubes, under the direction of Mr. Elmer H. Lewis. The course consists of a series of lectures and laboratory ex- periments which cover this interesting sub- ject in all its phases, embracing thirty-six class sessions of 2 hours each, 7:30 to 9:30 p.m. on Monday, Wednesday, and Friday of each week, the students being entitled, without extra charge, to all the privileges of the Y.M.C.A. The vacuum tube is playing a most important part in modern radio, and a thorough course in this fascin- ating work will be of inestimable value and interest to live amateurs, to licensed oper- ators, and to the more advanced experi- menter. We are very glad to see the action of the Y.M.C.A. in establishing this course, and sincerely hope it will meet with an enthusiastic reception. There must be something to the business of running a rotary gap at synchronous speed. Many amateurs report that when varying gap speed in a variable speed motor, there is an adjustment which can be held for a few minutes which will great- ly increase the radiation for its duration. Interesting possibilities here. It has been suggested that the occasional falling in phase which would occur in normal oper- ation in many cases, might account for some of the swinging of our signals. Mr. A. L. Groves advises us that two Marconi Class II bulbs conneccted with all elements in parallel, and used as a detector, will give somewhat stronger signals than a single tube. This is because the char- acteristic curve of tubes in parallel is steeper than of an individual tube. This would make a cheap amplifier as the only additional expense would be the double drain on the A Battery. New operator at 9QJ, St. Louis. Mr. and Mrs. F. W. Forshey announce the birth of their son Leo Hadley Forshey on Aug. 30th. Congratulations, Fritz! ’"Nother radio romance. B. P. Williams, 8EN, Pittsburgh, met, courted, and won as his bride Miss Marian Carson, of Spring- dale, Pa., sister of R. M. Carson, 8RQ, official A.R.R.L. operator on Trunk Line B in Rennsylvania. This lady has forsaken the musical comedy stage to marry a radio bug and doesn’t know what an awful thing she has done—but she probably will this winter. The newspapers featured the story so that on their trip they were pretty well known by the hotel clerks, and 8EN mentions that it “sort of QRM-ed the party.” Hi, Brother! Mr. Arthur Batcheller, formerly of the Massachusetts Radio & Telegraph School,

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40 prin no h a : dur y interes Radio’ LR.E have sectior certall Wel Statio1 publi it? The compile Audiol the Ra DeF ors Tron ¥ had a The fa hand-n new n the sir standar compat content Tron, work + A D-Wat OscilTr his oac QsT lio Inspector for the Port Krumm having resigned nnect himself with the lio Telegraph Co., of New ng anything in the way n a loop? The Editor on the subject, please. ho want a little set to there is no excuse for trouble and expense of plete set. A small buzzer cey and battery on the nd ground to the arma- ry electrode, being care- e resistance of the wind- rial circuit. Johnson, Jr., (“Ted” to Chief Radio Aide, U.S.N. Commander 8S. C. Hooper, in Charge, Director and t of the Radio Club of ently married to Miss ttson, of Chicago. Mr. old-time amateur, his he olden days being to slide tuner in a manner | follow in a diagram. He part in the organization reraft service of the Navy nd is the author of a very - entitled “Naval Aircraft presented before the erstand Mr. Johnson will nt position in the radio General Electric Co. He r good wishes. that “Grand Central York surely got enough \ugust magazines, didn’t Sales Co. announce the negotiations whereby the vy regularly licensed by ‘f America as well as by amateur uses. The Audio- marketed in 1915 and has rd legal battle ever since. filament tube has been with increasing demand being prepared, to he of nt type mounted on the base. In October this plates marketing a gas r tabe known as the Audio- cuum tube for amplifier » as the AmpliTron, and r which will be called the to know where 7I got eostat October, 1920 Lou Pacent points out that his new trade-mark is a Hertzian oscillator and not a wedding ring, and he hopes nobody will mistake his advertising for that of a mail order jewelry house. 9AIK suggests the use of old phonograph “needles” as switch lever stops. Drill a hole a little smaller than the needle, and force them in. New books received: “Wireless Tele- graphy and Telephony’’, by H. M. Dowsett, M.LE.E. 331 pp., 8%x5%, published by The Wireless Press, London and New York, 1920. A typically British textbook, de- signed to act as a connecting link between the elementary text and the advanced treatise, and in particular to meet the de- mand for book which can be used in se- quence to Hawkhead & Dowsett’s “Hand- book”. Particularly good chapters on atomic theory, and exceptionally complete chapters are devoted to the accurate measurement of voltage, current, resist- ance, capacity, inductance, frequency, dielectric strength, and decrement, and it will no doubt be of value to American readers in search of data on these subjects. The price is $3.50. WOULDN'T IT BE WONDERFUL— If 3RW didn’t start every conversation with “QSA OM”? If Ma could find her paraffine, now chat she wants it? If we could get all the apparatus we wantea by merely walking down town an¢é paying for it? (From a North Dakota ham.) If my dad would let me stay up at nigit as long as I want te? (Yep, Lil’ Willie ) If the traction compznies would supp.y us with 550 D.C.? If NPL’s arc was on Mt. Ararat with Noah’s? If Johr: Barleycorn had a set? (He used to be good at sending out fits!) If the O.M.’s cat got a bath? If “wireless” was really what the name implies? If 18Z shovld forget to test his trans- mitter after + o’clock some night? If NAF wasn’t the training station for all the ham cps in the Navy? Davia L. Moore, 1BBL, Farmington, Conn., gave to the world thru the Associated Press its first news of the S-5 accident, having copied the SOS of the S.S. General Goethals. It is said that naval officers at the Philadelnhia Yard obtained their first knowledge of the accident when —s _ information on the subje:t by the A. P.

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October, 1920 Conducted by Guy R. Entwistle SPARK GAPS proper selection of the spark for the primary circuit may decide the success or failure of the transmitting set. Its function is to permit the condenser to become properly charged at one instant, and at the next instant release this energy for the creation of wireless waves. It also determines the amount of coupling that can be used with any particu- lar installation. Thus we see it not only governs the character (broadness or sharp- ness) of the emitted wave but also its strength to a certain extent. In general amateur practice we find three common types. The plain gap, the HE gap rotary, (synchronous and non-synchron- ous) and the quenched gap. The first type is used with spark coils and low powered transformers. It usually is made from two flat surfaces supported horizon- tally with a variable adjustment for spark- ing distances. Zinc, nickeled steel, alumi- num, or coppper can be used. A more common type is synchronous or plain rotary. Mechanically it consists of a rotor on which are fastened at equal spaced inter- vals, studs or electrodes. This is set in motion by any smal] motor of suitable size and speed. The connecting shaft must be well insulated if the rotor is all- metal. In some cases the rotor is made of bakelite or hard rubber which elimin- ates any necessity of shaft insulation. Common spark frequencies used in radio are from 120 to 1000. By frequency we mean the number of times PER SECOND anything occurs. Hence when we say a rotary gap gives us a spark frequency of 300 we mean 300 complete sparks have occured in that second and each spark represents a COMPLETE DISCHARGE of the conden- ser in the primary circuit. Also, each complete discharge of our condenser creates a separate wave train of oscilla- tions. Therefore spark frequency and wave train frequency are one and the same. The tone in our the non- receivers is governed entirely by the spark frequency at the sending station. Below is a table that will be found help- ful in selecting the proper frequency, or number of studs for any motor of a given speed. Before starting on our search let us refer to last month’s article in which the subjects of high and low spark frequency were discussed. In general a _ resonant type transformer works best with a low spark frequency, while the non-resonant type lends itself to higher frequencies. Low frequency is around 200-400 while anything up to 1000 can be taken as high. 600 or 700 is the usual upper limit among amateurs. Low High R.P.M. Studs Spark Note Studs Spark Note 1200 14 280 28 560 1800 10 300 20 600 2400 8 320 16 640 3600 4 240 * 8 480 Example—If the motor goes around 1800 R.P.M. and you have a resonance type transformer which works well around 300 for a spark frequency turn to first column and on the same line with 1800 in this column will be found 10 in the second column. Hence we need ten studs on the rotor at this speed, 1800 R.P.M., to develop the required frequency at the gap. Bear in mind this frequency we are now dis- cussing has nothing whatsoever to do with the wave length. OSCILLATION fre- quency is the deciding factor in this latter case. The two groups of figures will be found to be near 600 and 300 respectively, in all cases in the table. Departure from the table will not harm in most cases, pro- vided the amateur bears in mind the cen- necting relation on which it is made; namely, SPARK FREQUENCY=R.P:S. x STUDS. R.P.S. can be found by dividing the REV. PER MIN by 60. For a higher spark frequency, say 600, and the same motor speed, 1800 R.P.M.., the second group of figures shows we need 20 studs on the rotor. Notice that twice the spark frequency requires just twice the number of studs for a motor of con- (Concluded on page 48)

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42 QsT ~= — a — idio Communications _ by the cAmateurs. October, 1920 ~ quel, es The Rs or QST ASSUME NO RESPONSIBILITY FOR THE STATES E NEREIN BY CORRESPONDENTS ® . . MORI ISM OF “PROF. BUGS” the total resistance, not the radiation re- sistance alone. It is the total resistance, ld Street, N. W., then, that should be considered. Ww ashington, D. C.. The total resistance of the antenna may August 19, 1920. be conveniently measured by adding series Editor. resistance to the antenna circuit till the In 1 number of QST in the current is halved, when the added resist- unsign« lo the Old Man and ance equals the antenna resistance. The Other neous statements were Yegular spark set may be used for this pur- mat pose but the coupling should be Ioosened The ese is that the watts input considerably. Precautions to be observed to an al are that the series resistance is correct P at the operating wave (very few resistances ps - ; » are correct at 200 meters) and that the rr, the radiation resistance. antenna meter is correctly calibrated. This ect. The value R given in Most amateur meters are very badly off— this equ t the radiation resistance anywhere from 5% to 50%—at 200 me- but the ntenna resistance. This ters. total composed of the radia- The method of adding series resistance tion re ohmic resistance of the may also be used with an oscillator but the grou! ind the antenna wires, oscillator must be one which has its own and f resistance due to the de- tyned circuit which is coupled very loosely fective n the field of the an- to the antenna so that only a very small tenna total resistance that is part of the possible output of the tube ap- measul stitution method which pears in the antenna. The ideal condition =o the bottom of page 49. is that no appreciable change be produced The n t emphatically does not jn the current in the closed oscillatory cir- measur ition resistance; in fact cyit when it is placed in resonance with there i ent no good method of the antenna circuit. With an oscillator of measut rit any ordinary size this means that the an- Rad tance may be calculated tenna current will be quite small so that by me rmula a thermo element and galvanometer will H’ 1600 be needed to measure it. Such a combina- — tion is normally a current squared instru- ment, hence the deflection with half cur- but the t that the formula “is Trent will be %4 that of the full current. accurat for all ordinary results” Where the substitution method proposed is anyt rrect. The formula is a im the article under discussion is to be used, very | ft which we use for lack 2 precaution must be observed which the of anyt writer of the article probably had in mind Furtl neorrectly used here. but did not emphasize. Both the substitu- The he the full height of the tion method and the series resistance antenn eight of the center of method depend upon the assumption that eanacit nce which is considerably the e.m.f. produced in the circuit under smaller ntenna height unless the measurement remains constant. This con- top is 1 proportion to the lead. dition is easy to meet in the series re- in an 1s the top is not much sistance method. In the substitution longer id. As the term enter method the only sure way to obtain the into 1 n the second power the same e.m f. in the dummy circuit as in the valme of resistance obtained by 2™tenna circuit is to use the same coil, “Prof much too large. ~ first as the antenna coupling inductance The } senishanes detnalend and then as the dummy inductance, the ae acl ~ e of onty oscillator or spark set primary coi] being —— Prof. Bugs” is con- kept at the same distance as before. In Cas irrent that may be ex- case an antenna !oading inductance is used nna of a one kilowatt jt must of covrse be used at the same pected te tranamit this current is limited by position in the dummy circuit.

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| October, 1920 Measured by the substitution method the antenna at 1AW has a resistance of 5 ohms at the operating wave length, the radiation resistance being a part of this A current of ten amperes in this antenna would represent an input of 10x10x5=— 500 watts. This is a large, but not impossible, in- put for a one kilowatt set—always assum- ing that it is possible to build a 200 meter, 60 cycle set which will have an input of one kilowatt. Like Mr. West, I would like to see such a set. “Prof. Bugs” states that the value of the resistance used in the dummy circuit may be measured on a Wheatstone bridge. This is correct only if the measurement is made at the operating frequency, the bridge is one designed for radio frequent measure- ments and the resistance used as a stand- ard is carrect at these frequencies. As stated before, very few resistance boxes are even approximately correct at 200 meters S. Kruse. ELIMINATING BLINKING 3483 West 98th St., Cleveland, Ohio, August 16, 1920 Editor, QST: I noticed in the August edition an article on light blinking. I am using a simple hook-up which completely does away with this trouble. A separate set of contacts must be placed at the rear of the key, one on the base and one on the lever and hooked up according to the diagram. / (00000000) OO) | } fuse | EATRA SET OF CONTACTS ~h i See > | 1 crRocK Ht tt Mid th) Sects KEY ~ 4 il SALTY WATER. o Us? a BRASS RIBBON Procure a three or four gallon crock, fill it three-fourths full of salty water. Cut a strip of wood a little longer than the dia- meter of the crock, drill two holes three inches from the ends and slip some brass tubes or rods in these. Have them fit snugly so they can be adjusted. Have the wire connecting the brass ribbon hang over QSsT 43 the wood strip so it can be slid back and forth for adjustment. With this hook-up the transformer voltage can be regulated and also the light blinking stopped. Yours truly, Arthur Schulder, 8AGB. SIMPLE RADIOPHONES 251 Union Ave., Rutherford, N. J., New Jersey, Editor, QST: Most of the articles one sees in the elec- trical publications on Radio Phone Trans- mitting Sets have to do with the use of a generator or rectified A. C. to deliver the plate current, but the price of these in- struments and their scarcity makes it im- possible for most of us to get them, although most amateurs would like to have a Phone Set working. A few weeks ago I hit upon the idea of using “B” batteries and getting the de- sired voltage in that way. I am using 5 standard “B” batteries delivering 110 volts to the plate of the vacuum tube. I use a very simple feedback circuit, the center connection on the secondary running to the filament. This circuit has been pub- lished many times so I will not give it again. I put up the set mostiy to work with fellow amateurs in my own town. It worked fine, voice QSA on galena within a radius of two miles. A few nights later I was working with a friend when an ama- teur in Montclair called me and said he was getting me fine. That is about 7 miles from Rutherford. I was very much sur- prised and pleased to know my signals were carrying that far. A few days ago 2WB in Bay Ridge, Brooklyn, put up a similar phone using 150 volts on his plate circuit. He is about 20 miles distant and I yet him very QSA here, coming in at times almost as loud as another amateur in New York City using three tubes and radiating over 1 amp. 2WP gets me very good using a two step amplifier, signals being heard on the second floor. It only took me about an hour to rig up this set, and I think it would pay any ama- teur to try it. I can use it with buzzer modulated, voice modulated, and straight CW. A small hot wire ammeter reading from zero to point five is needed in the ground lead so as to know the best adjust- ment. I am radiating 100 milliamperes on 325 meters. I hope this will be of interest and help more amateurs to get CW sets working— we need them badly for local work. If anyone hears 2MW, please let me know, as I would like to get the range of this set. Very truly yours, Harry B. Wattson.

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44 QsT DISTRICT PEP 15 Vineville, Ave., Macon, Ga., lays ago in the July e wonderful for the little more pep. Things have looked t season and seem- i of better. | was one of the Tech. in Atlanta, od chance to get a tions. Here is how can take messages 1 north-western sta- t enough for us to lin) but when these ta they have to stop ough Mr. Burleson’s en, when two or mack marked “Party ttle bit discouraging. ed just what kind of . and several of the yut us fellows down that it is anything just couldn’t be ty good come-back just about evens up r Atlanta men sent mother who was n hospital and not one gh to her. We would ne station and then e next man about t was the last we could ind out of about six yne was delivered. rict wasn’t the only so don’t ““‘ride” us we have been ’t seen a division Gulf since April. are not quite dead yu don’t have much think you will hear Division as soon as ‘and we can begin DX work. We are ere in spite of the probably hear from even a few minutes nee the re-opening of Atlanta. Friend 1an 80 miles from nes work 4AT and me success but we through to them. iid his set and is not ts to get back in the t is not very often t from Atlanta to Athens ‘ nditions unusually ' teady work over this gh both of us can do October, 1920 DX work right along. 4AE at Jackson has not been on the job as his work carried him to another town, but I think he will be back again too. It will be a great loss if we have to lose both 4AE and 4A0 too. Just a few weeks ago I worked 4YB, K. of C. in Savannah, and then exchanged mes- sages with 4BQ in Rome. Neither of these stations came in very QSA but think we can work both easily from Atlanta with better weather. Both of these should prove very valuable in relay work. Have never gotten 4AN in Boston, Ga., good except the night before I left Atlan- ta about three weeks ago. Tried hard to raise him then but he failed to get me. There is a good station going up in Ma- con now, 4DA, and it should prove to be another valuable link in dhe relay chain. We would have heard from this station be- fore if he had not been requested like some of our Northern friends to “just about buy the power company.” We should be able to “go west” easily from Atlanta as we were able to work 5YE, University of Mississippi, for some time and exchanged several messages with them. 5XA, Auburn, Ala., also began to come in good just before we had to close down in Atlanta but on account of extremely heavy static we could not work them more than just exchanging signals. It would seem that with the stations we had this spring and with the number of good stations increasing during the sum- mer that we should get busy and make our arrangements now for work next fall so we will be ready to work as soon as the air “clears up”’. Say OM, here’s a good one. One of our Atlanta members made a business trip up east a short time ago and while there called on a few amateurs in Boston and New York. During the conversation at a station near Boston, the owner complained of not hearing 8’s and 9’s and other DX stations. The man from the south looked the set over, changed a few connections, rigged up a grid leak, did a little more to the set and in a few minutes had Mrs. 8ER and some of her neighbors on the line. The northern man was of course delighted but as his visitor started to leave, innocently asked him when the south was going to wake up in the radio game. Hi Hi. Can anybody tell one that will beat this? Just wanted to let you know that we were stil] on the map and trying to do a little work so will QRT now. 73. Yours truly, E. H. Merritt. AN AMATEUR DID IT Editor, QST: Chicago. An instance when amateur radio was put to practical use occurred about 7:40 P. M., June 10th.

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October, 1920 U. S. Mail Plane No. 206, having been delayed in leaving Cleveland for Chicago, was due to arrive at Maywood Field about dusk. The following request was broad- casted from plane when near Chicago: “QST U. S. Plane No. 206. “QST U. S. Plane No. 206. Any station hearing these signals please notify Maywood Field of the Aerial Mail Service that 206 is coming into Chicago. Please phone Maywood Aerial Mail Field.” This message was phoned as soon as pos- sible, although some delay was experienced on account of difficulty in obtaining tele- phone number. The newspapers of next day reporting the incident stated that message was re- ceived at several amateur stations but gave Great Lakes Radio Station credit for ser- vice rendered. Attached you will find letter from Post Office Department acknowledging receipt of message and confirming facts as outlined above. An indoor aerial was used for reception of message at my station. Yours truly, W. J. McGuffage, 6120 Evans Avenue. Mr. W. J. McGuffage, June 26, 1920. 6120 Evans Avenue, Chicago, Ills. Dear Sir: Receipt is acknowledged of your letter of the 16th inst., regarding wireless mes- sage received by you from United States Mail Plane No. 206, at your radio receiv- ing station, on June 10th, and in which you ask confirmation of telephone message that yours was the first information to reach this field regarding the arrival of this plane. In this connection, I beg to advise you that departure of ships from one field for another are always telegraphed promptly when ships leaves field. The departure of plnae 206, on the 10th instant, was report- ed from Cleveland in the usual manner. The Chicago station is not equipped to re- ceive wireless messages and the exact time of arrival of this ship could not have been communicated direct to this field. I de- sire to thank you, therefore, for the service rendered in that instance. Respectfully, A. R. Dunphy, Manager. ULTRA-ULTRAUDION. East Orange, N. Y., March 11, 1920. Editor, QST: I am enclosing a simple works great. I feel sure that the many readers of QST will be “tickled to death” with the results obtained by using it. circuit that QsT 45 It is an adaption of the Ultra-Audion circuit. The Ultra-Audion hook-up is all right, but—I’ve added another variometer, Vil, which increases its efficiency by at least 50%. Trouble with the straight Ultra-Audion is that the degree of regeneration obtained is not readily controlled. By varying the coupling in the variometer I’ve added, ANY DEGREE of amplification can be obtained. And it’s got them all stopped for radio phone reception! Hi co [htt HOO | V is a tapped variometer, Sears Roe- buck, SCR-54. V1 is an untapped variometer wound with very heavy wire, preferably Litz. C is a 43-plate variable condenser. C1 is a 23-plate variable condenser. G.C. is, of course, the grid condenser. I trust that this will find space in an early issue of your magazine and wish QST abundant success. Very cordially yours, G. N. Garrison. ON REDUCING INTERFERENCE San Francisco, Cal. Editor, QST: A great deal of complaint has been noticed from the amateur field at large, and especially from those situated in the near vicinity of the 600 meter shore sta- tions, that these stations cause untold trouble due to “broad” (?) waves. Pos- sibly with the old 60 cycle non-synchro- nous set, or a straight gap set in use this would be perfectly logical, but how many ever gave a moment’s thought to the fact that this apparent broadness might be due to a broadly tuning receiver? Not many, I warrant. It is perfectly ridiculous to claim that a naval or commercial station using a modern 500 cycle quenched gap transmitter is, or can be emitting a broad wave, if it is properly tuned and, as the de- crement of such stations often is as low as 0.03, which is really extremely sharp, and it is believed that this is only the natural antenna decrement, due to its resistance, rather than to any decrement due to a re-

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46 QsT action he circuits. If interfer- enc: waves differing from the operati! f the receiver, it is really self-ev is the fault of the re- t that of the transmit- (This is aimed particu- who claim that NAH and NPG h vaves on quenched sets). Now per adjustment, the re- ceiver isted so that there is no interf: le, provided the unde- ired of one single frequency (wave has no bad harmonics. The liagram shows a circuit by wil accomplished. ceiver ting e larly at

x KKK KY 4) — 4 IK

Ee Tuner

¥ The esents a regular receiver, whicl common type, regen- erative which is indicated by TUNER ed series circuit is the thing trick, and it does not have t ed or fooled with, once it is conn ljusted pro erly. This alled variously a “bug’’, “trap” circuit”, is nothing more or less t bination of capacity and inductar ented by L, and C,, con- nected a in the antenna lead of the rece circuit, as can be readily seen, < 1 simple tuned circuit, the wave-len vhich depends entirely on the valu inductance and capacity connecte s it. THIS MUST BE TUNED HE WAVE OF THE SIG- NAL IT I sSIRED TO ELIMINATE IN THE RE‘ ER At first glance, this seems strat 1 unusual, but its expla- nation i ws; if we have a tuned circuit, of capacity and induct- ance, thi will have practically zero resistanc¢ current of a frequency different t vat the circuit is tuned to (i.e. its 1 eriod), but to its own fre- quency tl tance wil] be infinity, or in other v current will pass through

October, 1920 it at all. Now if such a circuit is connected in series with the antenna of a receiver, all the oscillations of different frequency than that the circuit is tuned to will pass through it freely, and will excite the tuner in the usual manner; if, however, oscilla- tions of the frequency of the series circuit impinge on the antenna, and travel down the lead into the receiver, méeting with infinite resistance, they will be stopped, and the interference eliminated. Practically, the inductance L, and the capacity C, may be almost anything within reasonable limits, provided the wave- length of the undesired station is known, as it generally is. The inductance may be a simple coil of wire without taps, on a cardboard tube, and the condenser may be a standard variable of any well known type, or the old long-forgotten tuning coil may be dragged out of the dust in the garret, and connected in circuit with a small fixed condenser. For 600 meters or thereabouts, if no old material is available, however, the “trap” may be constructed as follows:— take a cardboard tube, say 3” in diameter, and wind about 45 or 50 turns of No. 20 wire on it. Shellac, or paraffine, or other- wise secure the wire in place. Now con- nect a variable condenser across it, and connect a crystal detector across the termi- nals of the inductance, with a pair of tele- phones in series, in the manner which you ordinarily connect the detector in a wave- meter. Now excite the trap with a buzzer driven wavemeter, and tune to the wave wanted. Now disconnect the phones, and detector, and connect the trap in the an- tenna lead as shown, and lo! the QRM has vanished. For other wavelengths other coils must be used, or a honey-comb coil, or in fact any inductance and capacity which will tune to the undesired wave- length will be all that is needed. Never use too large a condenser, however, but rather use a larger inductance. It is not desir- able to exceed 0.003 capacity at most in the condenser. Different traps may be made, and con- nected in series, if more than one station is interfering with reception at any one location, and if properly constructed, so that no extraneous inductances or capacity are introduced into the trap (always use the shortest possible leads) there will be no loss of the desired signals, or leakage of the undesired signals into the receiver, although a difference in the adjustments in the tuner primary circuits will in practi- cally all cases result. Yours truly, D. B. (Note: We certainly cannot agree with our correspondent’s statement that inter- ference from naval or commercial stations is generally due to imperfections in the receiving equipment. How does he account for this interference when obtained on a

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October, 1920 modern short wave regenerative receiver, which tunes sharper than any other tuners we know? We believe it is true that there will be no interference on 200 meters from a quenched transmitter on 600 meters when the latter is properly adjusted. The trouble is that they are often improperly adjusted. Some of these sets have arrangements for wave-changing which do not perform all the necessary actions, such as coupling cor- rections, that last shade of fine tuning necessary in a quenched set, etc. These are supposed to be done by hand, and of- ten aren’t. Others of these stations seem to have been tuned by people who were far from knowing their business. In others the inspector’s tuning has been disturbed. At any rate we know beyond question that some of these stations have been causing unwarranted interference on amateur waves. Chicago amateurs recently com- plained officially regarding NAJ, we under- stand, and upon investigation it was dis- covered that on its three short waves the decrement of this station exceeded the legal .2. NRH was similarly found to have a decrement of .237, due to mistuning, and was corrected to .065. At NAM, a 5k.w. 500 cycle set, the trouble is from another source. The authorities are co-operating and investigating the trouble. We under- stand a strong wave is radiated by that sta- tion on almost exactly 200 meters, although the decrement is but .04, and exists as about 10% of the total r-‘iation on 600 meters, and about 8% on ¥52 meters. It has been discovered here that the trouble is due to re-radiation from the towers, and steps to correct this are now being taken. We suggest that c':ibs in localities ex- periencing unwarran‘t d interference from Navy stations take u» the matter with the Naval Communications Service, Washing- ton—we know they will gladly co-operate. Regarding our correspondent’s QRM eliminator, we believe it will work in the ease of forced oscillations where the trans- mitting station is very sharply tuned, but like all other devices of this kind it is in- effective against the components of the in- terfering energy which represent other than its resonant frequency— it is helpless in the case of a broad wave. We can hope, however, that it will be of much help to amateurs troubled by forced oscillations from a nearby powerful station.—Editor.) BLINKING LIGHTS i. ~ Cambridge, Mass., August 21, 1929. Editor, QST: We have read with interest the commvu- nication in the August QST from Mr. M. E. Ross on blinking lights and wish to say from a manufacturers standpoint this method is unsatisfactcry as radio transfor- QsT 47 mers are not designed to stand a continuous load. If they were their costs would be considerably greater. The most satisfactory way to eliminate blinking lights to have a double contact key which when down closes the circuit into the transformer and when up closes the circuit through the resistance of sufficient value to draw an equal amount of current. The reason for using resistance instead of an inductance is to eliminate arcing at the key. By the above method blinking lights are eliminated by making the “blink continu- ous.” Very truly yours, ACME APPARATUS COMPANY, per C. F. Cairns. (Note: Readers are requested to see a letter entitled “Eliminating Blinking’’, in this section.—Ed.). LOG SYSTEM 384 Hobart Avenue, Summit, N. J. Dear Eddy: In the last issue of QST I noticed that you wanted to hear from some of us boys on the subject of keeping a good log. I won’t guarantee that it is a good one, but it certainly works great at my station. A note book is kept with 8 ruled divis- ions; they are labeled; Date, Time, Call, Working, Amplitude, Secondary Adjust- ment, Primary adjustment, and Amplifica- tion, respectively. When a station over 100 miles is heard these divisions are filled out accordingly. At the end of the month these records are all gone over and all new stations heard that month are listed indi- vidually on a card about the size of an ordinary post card. The stations call is placed in large letters at the upper left- hand corner. These cards are ruled the same as the note book with the exception that there are only five divisions labeled Date, Time, Working, Amplitude and Am- plification respectively. The adjustment is placed in the upper right-hand corner. These cards are then filed according to dis- tricts and alphabetically in each district. A complete personal record and adjustment of every DX station heard is then always on hand. When a fellow wants to know if I have heard his call, one look at the records will find out whether he has been heard or not. The complete data can then be sent to the station, without the least bit of trouble It also comes in handy when listening for e certain station. By means of the adjust- ment record the exact adjustment of the receiver can be ascertained and there is no need of constantly tuning over a wide range of wave lengths. I have been using this system for quite a while now and I find it a great help. Yours truly, I. R. Groves, 2DX.

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48 pre’ rot QsT NKNOWN PHONE SET Camp Lewis, Wash. issue an article about ; south of Tacoma with a misunderstanding. 18 miles south of Tacoma CL-one...—.? Itis f the 59th Regiment, C. I am at CL2, the Brigade Headquarters ilso have BI4 of the 14th radiophone. BI4 and Western Elec. sets. We ench sets at CL2 and radiophone, and some 1y. Our sets are for 2 miles and work fine t no good for long dis- ’s are good for 60 miles with good aerial and stretched to about 300 spark set here at CL2 r condenser and short- n we are going to talk r Neville R. Benoit, 7BC. E ABOUT XAJ ~ Mt. Morris, IIL, August 17, 1920. letter on XAJ, Tampico. self about the middle me queer happenings. the Panuca River, still | I had some traffic for e, the second time on Couldn’t get him at r NAT and NAY through tatic. Was called by 1 QSQ—XAJ. I then one-half k.w. and he ring. He said he had before. My set and as evidenced by NAT » by test. Now why? ours, E. .R. Tilden, NIOR OPERATOR rrom page 41) 1e effect can be pro- speed and using the t the DIAMETER of to do with the num- per second, or the wever, an important ency of the gap. In the diameter of the Mechanical difficulties from increasing our October, 1920 The amateur will be well repaid for any labor along this direction. The reason is as follows: When the moving electrode, or stud, approaches the stationary stud, the spark jumps to meet it. At the next instant the two studs are opposite and an instant later are becoming separated. During all this time the primary circuit is virtually closed and the energy surging back and forth. At one time it is being passed over to the secondary and at the next moment is being passed back to the primary. This is against all principles of efficiency. Once it has been passed over to the secondary it should remain there until it has been converted into radiation. Hence we see the necessity of shortening the time interval at which our two elec- trodes are in use. Or, in other words, shortening the life of “spark” in the primary. The next question is, how can we do this? Without going into mathematical details which are out of place here, the answer is to increase the DIAMETER of your ROTARY. 1AW has a rotor around two feet in diameter. NAA’s is around FIVE feet. Those who know what is meant by LINEAR VELOCITY will understand the importance of a large diameter. Another important item in the design of a rotary is the proper shape of the studs. The sparking surface should be narrow. Both stationary and moving elec- trodes (Studs) should be mounted hori- zontally, similar to the blades of a water wheel. This helps in shortening the life of the spark. In practice it is impossible for the am- ateur to send out a single wave with a rotary and still accomplish any distance. But the Government has fixed the strength of the other waves not to exceed TEN per cent of the energy of that in the main wave. It is due to this FEED BACK from primary to secondary that we have to use such LOOSE coupling. This means a loss of energy for our antenna circuit. Thus we seo the tyne of gap nsed roverns the amount of coupling used. This in turn determines the amount of energy we succeed in p*ssing over into the antenna which, as we know, determines the distance to which we transmit. One of the disadvantages of the rotary is that is makes much noise. This can be overcome by enclosing it in a box picked with felt or any other material] that will absorb the vibration. Many manufacturers advertising in QST offer complete rotors and stators which will make a good rotary for the amateur. The synchronous gap will be taken up next month.

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October, 1920

CALLS HEARD

On account of the vast quantity of calls reported we must ask your co-operation in the following. (1) List the calls on a separate sheet of paper—do not embody them im a letter. (2) Arrange by districts from 1 to 9, and alphabetically thru each district; and run them across the page, not down a column (3) Put parentheses around calls of stations also worked (4) Omit initial or other unauthorized calls. (5) State the period covered by your report. 1AAC, FRAMINGHAM, MASS. 1AW, 1BM, 1FQ, 1FT, 1QP, 1RZ, 1SZ, 1TS, 1YB, I1KAY, 1PAM, 2AD, 2BB, 2BH, 2CK, 2DA, 2DC, 2EW, 2BK, 2GE, 2GU, 2JE, 2JP, 2JU, 2GM, 2LL, 2MEK, 20A, 20M, 2RG, 2RL, 2RR SJ, 2TO, 2TF, 2WN, 2XJ (spark and tel.), 2YN, 2ZL, 2ZA, 2ZC, 38CF, 3CV, 3DH, 8EV, 3EW, 3HJ, 3NN, 8ZM, 4{AL, 4LF, 8DA, 8BU, 8BP, 8IN, 8JU, 8EN, 8XU, SWY, 8NN, 9AU, 9ZN. 8MT, UNIONTOWN, PA. 1AN, 1AU, (1AW), 1CC, 1GB, 1GR, 1HAA, 1IZ, INC, 1RN, (1YB), 2AE, 2BM, (2BK), 2BN, (2CS), 2CH, (2DA), 2EF, 2ET, 2GC, 2GL, 2IK, 2JA, 2JE, 21M, 2JU. 2KM, 2NB, 2XJ Telephone RB, 2ST, 2VA, (2XX) Telephone, 2ZS, 2ZL, 3BH, 3BT, (8BZ), 3DZ, 3EA, 8EF, 38EI, (SEN), (3EW), 3GA, iGO, 3GX, (3HJ), 3IB, (3MU), 3MV, (3NB), 8NK, 83NV, 8PC, (3ZA), 8ZM, 4AE, 4AL, 4AN, 4AM, 4AT, 4CC, 4DD, 4DO, 4EJ, 4YA, (YB), SDA, 5AN, 5AQ, 5HQ, 5KA, 5GZ, 8AAM, (8ACF), SAP, 8AJ, 8AZV, (8BB), (SBP), (8BQ), 8CH, SDA), 8DC, (8DH). (8DI). (8DR), (8DS), 8DU, (SDV), 8EC, (8EF), (SEN), (8EO) (8ER), (SEJ), (8FD), (8FS, 8GA. (8GC), 8GJ, 8GP, 8GQ, SHA, SIF. SIK, (8IN), 8INN, (8JQ), (8JJ), (8LA), (8LJ), &8MD, 8NP, 80C 8OI (80J) (8PW), (8QG), (8RS), (8SP), 8VC, (8VQ), 8WA, 8WG, (SWR Telephone), (SWY), 8XA, (SXK Telephone), (XU), (8YI), 8RQ, 8GS, 8FO, 8NG, 8ZNC, 8WB, 9FG, 9KV, (90J), 9TR, (9ZL), 9HR 8NB, ROCHESTER, N. Y., May. 1AE, 1AS, 1AW, 1BU, 1CE, 1CK, 1CV, 1DQ, 1FW, 11GB. 1KA, 1KT, 1RZ, 1TS, 1¥R AA »AS. 2BB 2BK, 2BM, 2DA, 2DR, 2EF. 2EH, 2GE GR, 2JE, »1U. 2KM. 2ME. 20A. 20R. 20V, 2RRB TF, 20UE ? iN RA E RH eV FX ) x HA HR. 3HV IR. 3KM MK, 3NB, INP. 3NV SQ. NSF. 4AG, 8AA, 8AJ, 8BB, 8BG SRM SRP. SBQ, SBU. 8CB. 8CC. SCE, &8DA, 8DE RMI SMV &8DZ. SED, SEN, SER, 8FI, 8FO, 8FT 8GQ 8HH, SIK, SIL. 8JU, 8KW. 8LA, 8LW, 8MC, SMT. SMI, 8NF, 8NI, 8PA, SPR, 8QJ, 8RC, 8RQ SRS 8SH. STF, 8WY, 8XA, 8XK. 8XU, 8YV, 8ZM, SZW. SAAN. 8ABG, 9CS, 9FG, 9MS, 9ZN 1AW, HARTFORD, Aug. 9-28 (1AS) (1CK), 1CM, 1FB, 1FV, (1JQ (1QP) 'TS). (1BBH). (1BBL), 1FAQ, (1HAA), (1NAQ), IVAD. 2BG, (2DA), (2DN), (2EF), (2JU), 2J1 2™N. 2MB, (2NF), 2ND, 20M, 2PV, (2TF), 3BE 3BG, 3BZ. 83EH. 3HJ. (3LG), 3NB, (30B). 3ZW RAM. (SBV). 8CH. (SDI, 8DY. (8EN); (8GS), S8IK, RMT, 8NI. 8SH, (SWY), (SXK), 8ZC, 8ZW, 8ZY, SHR, (NSF) 2YM, NEW YORK, August 1AS, 1AW, 1CM, 1DQ, 1FH, 1FV, 1TS, 1HAA, 3BG, C3L, 3EN, 3FG, 8FD, 8GV, 3GX 8HJ, 3JK

38ND, 83RW, 3VV, 3ZA, 3ACS, 4BZ, 8BV, 8DA, 8DI, SER, 8LX, 8MI, 8NI, 8QO, 8ZW, 9ZN, 3GX, READING, PA., Aug. 28 to Sept. 8 1AW, 1BM, (1DQ), (1PY),. (1RZ), (18Z), (LHAA), (2BK), (2GR), (2JU), 2J3Z, NF), 2TE Ww B, (83BZ), 83DL, 8EZ, 3FG, (3HG (3HJ) (3KM), NB), 8RS, 38VV, ZW, \DH), 3AOFI iCP, iDM, 8CV, 8DV, 8EN, (8EV), 8GI, 8HG, 8J5, SLX, SMT, (8NI), 8QM, 8RU, 8SH, 8U0, 8XK. H. POLLOCK, PAWTUCKET, R. L., August. 1AW, 1ES, ICK LHAA, ' VAD OA, 2RK, 2RM, SHB, 3HJ, 3KM, NSF, ER, 8HD, 8QM, 8XD, 9ZN. 2MN, BELMAR, N. J., June 11 to Sept. 5. 1AW, 1BBZ, 1BQ, 1CB l¢ . DQ LDY 1FAQ, IFV, 1FW, 1GAO, LHAA HO N 1RZ, >» 1VA, 3BZ, 3CZ, 3GO, 3HJ, 3VV, 8BV, 8DI, 8ER, 8QM, 8QV, 8WY, &8XK »AU IRY, CHATHAM, MASS., Aug. 30 and Sept. 4. 1AS, 1AW, iCM 1CZ Q l 10, HAA, 1RZ, 1SZ, 2BG, 2BK I N El U, 2ME, 2MN, NF, 20M, 2TS, 2WB, 2WZ, 2YM, ] SBG, 8EN, 8JS, 8SH, 8XK 8ME, BEAVER, PA., Past Year 1AW, 2DA, 2ZS, 2ZV, 8AI, 8AO, 8ACI, 8BP, 8BY, RDI SDK, SER, 8II 81K 2MR SMM STI, 8VM, SXA, 8XU, 8ZW, 8ZX, 9CS, 9DV, 9ER, 9HD, 9HR, KF, 9ZJ, 9ZL, 9ZN. CANADIAN SBR, VANCOUVER, B. C., July 10 to Aug. 9. (5AR), (5BK), (5BG B 6DP FE, 60H, 7AD, 7AH, (7BK), 7BU, 7CE, (7CU), 7CW, TDA, TDP (7DS), TFL, 7GR, TIN, 7JM, TNS§ 7YB. 7CU, VANCOUVER, WASH., August. (5BR), (6AS), (6AV), (6AR), (6BJ), (6BN), (6BQ), (6BR), (6CO (6DK), (6DY) (¢ A), (6EB), (6EJ), (6EP (6EX) 6FS (6GF), (6GR), (6IF), (611), (6JD), (631), (63M), (¢ (60C), (60H), (6PQ), (6QR) R) (6ZE) (7AD), (7AN) (7BK), iCE), 7CW (7IN).

1TS, BRISTOL, CONN., July 20 to Sept. 1. 1AAU, C.W., 1AG, 1AK, 1AS, (1AW ( and fone, IBAY C.W. and fone, BI l 1BM, 1CK, (1CM), 1CZ, 1DBU C.W IST v. QRA?), 1DQ, IDR, I1EAV, 1€EK, ‘ IFB, (1FBK) spk. and C.W., 1FQ, 1FV, 1 ) 1GJ), 1GY, 1HAA, 1IAO, 1JQ, 1MJ, (1NA‘ ) OAL, (1QP) C.W. and fon l 1SZ), 1UAW, 1XD C.W. and for ‘ A PAID AY oAM oR ‘ \. 2DI, 2DN EI GR NB, 2ND, 2NI NV ; ( t sp nd for } | oT} WB, 2WG XJ ne \ \ fone, 2ZM s} C.W BZ EH EV B, 3FG ) X, 8HJ, 83HX MU, 3NB OB, 3SJ VV LW, SBH SBP, 8BV CG, 8DA, 8DI V SEN, 8EW 8 F¢ SFW, 8FX, 8GS, 8G < IN, 8J 8JU MQ, SMT. SNI, 8OY, 8Q C.W., 8YV, &ZW -X p ME 973 ‘,- 8AD, BUFFALO, July 1 ug. 31 1AW, 1CK, 1ES, 1FV, 1N LW EH), 2JZ, (2J3U ON] RK). OTF WB). 3FG, (3HJ NB : IW At SAJN, 8BW, &CV. 8CH, 8C 3 RDA. (8 SDF), SER, sEN, 8GY, § LX LF. SMT. (SNI), SRS, 8SH, 8XK, NSF, » SAL: »ASH, 9HR, 92N (Concluded on pag )

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and 50 “FROM You Ww Signals which become easily ED UNDER ARMSTRONG AND MARCONI PATENTS AND HERE IT IS—T ‘eatest Improvement In Modern Radio ‘emember the super service of the old original RA-6 amplifying short wave receiver? This surpasses it in every respect he original RA-6 was the only one of its kind provement over the old original Paragon, away f all other receivers and excels the most service- t on the market today. irprises in store for you if vou will send for special bulletin lescribing this set. the old Paragon—this one beats it and all others by miles— ir special bulletin tells you hew. Send for it— it’s free. } AND THE PRICE The above set will be on exhibition at our Booth, « Our word of honor to you is our ; Continental Radio a J. DI BLASI, Secretary Sole Distributors of the P DEPT. B,2, 6 WARREN § ALWAYS MENTION QST WHEN W

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JM NOTHING TO SOMETHING” ou will do it— with this new Paragon RA-10 vhich on actual tests are inaudible with any other type of receiver, easily readable. ‘‘Coming from Nothing and amplifying to Something.’’ -[The Paragon RA-TEN Here are the 150% Pointers A Wave Length range of 160 to 1,000 meters. 24% more sensitive and selective than the RA-6. All amplification obtained without change of spark tone. Objectionable effect of change in note entirely elimi- nated. Coupling has seale of 180° instead of 90°, giving wider range of coupling. Controls on all adjustments fitted with vernier attach- ments permitting of very fine tuning and control. No dead end losses. Cabinet of quartered oak; overall size 20°4x8x71’; white filled engraving, bakelite panel, knobs and dials. Every set sealed before leaving factory, which is a guar- antee for two years. A super product of Adams Morgan Co.’s unapproach- able engineers. PRICE, $85.00 ooth, at the Electrical Show, Oct. 6 to 16, inclusive is our guarantee. Let us prove it. » and Electric Corp. of the Paragon RA-10 J. STANTLEY, Treasurer REN STREET NEW YORK VHEN WRITING TO ADVERTISERS 51

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52 QST October, 1920 90X, Lol KY., July 1 to Aug. 31. (NSI ‘ XL (phone), 3BK, 3BQ, SBZ iKK, 5DA, 5YH, 5YS, 5ZG, Al DA, 8DH, 8DI, 8DR, 8DV, Spx ER, 8GB, 8GR, 8IE, 8IK, SIN 8MI, 8MT, 8NI, 8NL, SN’ C.W.) 8XL, 8YQ, 8YV, &8ZW S AT 9ABL, 9ALS, 9BW, OFT IT, 9KO, 9KU, 9LC, 9MH, 9MS. 9M 90J, 9QJ, 9RM, SWC, WK , 9ZN, 9ZO, 9ZR, 9ZX. 1ES : NE, MASS., August. LAAT BM, 1CBJ, 1CM, 1EK, IFB AA, 1IAO, 1INAQ, 10E, LRZ \JW. 2AMZ, 2BG, 2BK, 2BM k N EL, 2GR, 2HN, 2JN, 2JU M. 20U, 2PL, 2PV, 2RK, 2TF M,. 3BG, 3BZ, 3EN, 3EH, 8FB HJ, 3HX, 3KM, 3MU, 3NB N IZA, 3ZW, 4CM, 8AD, gRO \. 8DI, 8DV, 8DY, SEN, SER, 8 K, 8LF, 8LR, 8LX, 8MI, SMT Y, 8XK, 8YV, 8ZW, 8ZY, 9ZJ 8 N. PA.. August. 1AW IXD (phone), 1FB, (1FV BG, 2BK, 2BM, 2DR, 2EF } NF), 2RK, 2TF, 2TS, 2WwB AAP —BG, 3BZ, 3CZ, am DN sHL. 3HJ, 3KM, 3NB, 3NU YH, SADE, 8AFL, (SRV SDE, (8DI), SER, (8FD LV, 8ZY, 9AD, SAT, 9GR CANADIAN ANEE, ONT., Aug. 1 to 23. LAR BI IBM, IGR, 1GY, 1HAA 1SZ, 2BG, 2BK, 2DN, 2EF 1Z, 2NF, 2PL, 2QR, 2RK ZL, 3HJ, 30B, 3ZA, RAD 8CI, 8DA, 8DF, 8DI, SEN I °GB, SHA, SHF, 8NI, SRN -. YV.. 8ZJ, 8ZW, 8ZY, 17N NX, N. Y. C. 1AW TF, 3BG, 8BK, (3BZ), cx INC, (83ND). (8VV), SRK DV, SLF, 8MT. &8TD, 2XR 3VV, - 15th to Aug. 15th. \W AAP BK, 2CA. 2CE, CM 2HW,. 2JA, (230) 7, ‘ iG, 8BL, (3BZ), 3CZ GK IR. (3JK), 83KM, 3LG, MT R RK, 8VA, 8VP, 3XI. tVvYK YM H YS, 7JF. 8BK, 8CF SDA, 8D GR, (S8IK), 8LA, 8PK, Sa

SVV, SYK, (8YV), 8ZW, 8ZY, 9ALS, 9CM, 9DG, 9GB, 9GX, 9HF, 9PM, 9RW, 9ZF, 9ZN, (NSF). 9AHC, ELLENDALE, N. D. On one wire, one variometer for tuner, and galena: 9ADZ, 9BW, 9JN, 9LW. 9PI, 9XN, 9YG, 9ZN, 92X INY, BELMONT, MASS., June 25 to fg 26 2BG, 2BK, 2DN, 2EL, 2GR 2JE, 2JZ, 2 2RK, oSH, 2YM, 3BZ, 3HJ, 3NB, 3ND, 3VV, nw SDA, SDV, 8LF, 8XK, NSF. 8ZY, DEFIANCE, OHIO, July 20 to Aug. 24. NSF. 1AW, (2BK), 2EL, (2GR), 2RK, 2ZL, (3BZ), 3HJ, 38ND, 38LG, 5A0O, (5YH), (5YS). SAIM, (SBP) (8CF) SCV, 8CD, (SDA), 8&DC, SDI, SDF. 8DH, 8DV, (SEN), (SFI), (8GB), (8GS). 8GY. 8HJ, (81K), 8IN. (8JJ). (8JU), 8NI, 8QJ, 8QO, 8SH, (8U0), (SWY), (8XA), (8XK), 8ZW. 9AAF, (9ALS), 9AE, (9AP), (9AX). (9HR), (9IT), 9KO, (9LR), (9NQ), 9PW, (9ZN), 9ZJ, 9ZL. 3AAR, NORTH GLENSIDE, PA., On Crystal. 1AW, 1HAA, 2NF, 2WB, 38BG, 3BQ, 3BO, (3DK), 8DR, 3EH, 3EN IFG. 3GH,. 8GO, 3HJ, (3LH), 8MX. 3NB, 3NY, (30T), (3PB), 3PG, 3PS, 3PW, 8QH. 8QQ. (3RU), 3RW, (3UF), 3VV, 3ZS, 3ZW, SABV, SBV, 8ML, SNI, 8SH, 8YV, 8ZW 8STY, JAMESTOWN, N. Y., Aug. 1 to 21. 1AS 1AW, 2AJW 2BG, 2BK, 2CT, 2EL, 2JZ, ®NF, 2QR, 2UE, 3BZ, 3EN, 3FR, 3HG, 3HJ, (V. 2SA), 8NC, 3VV, SACN, S8AIJ, 8BP, 8BV, SCI, SCV, SDA, 8EN, 8FI, 8GB, 8GS, 8IK, 8IN, SJU, SLA, 8LX. 8ML, 8MT. 8NI, 8QM, 8RQ, 8SH, SWY, 8XK, 8YV, 8ZW, 9ZN, NSF. 9ZY, LA CROSSE, WISC., July 10 to Aug. 21. 5DW. SED. 5YH, 5ZZ. SBP, 8BV. 8CF, 8DI, 8ER, SFI. SKV, 8XK. 8YV. 8ZY., 9AB, 9AU, S9AEK, 9AEH, 9AEQ. 9BW. 9CA, 9CS, SEL, 9FS, 9GN, 9HR. 9KI. 9KO, 9LC, 9LR, 9NQ, 9OR, O9PB, OPN, 9VR. 9ZC, 9ZJ, 9ZL, 9ZN, 9ZQ, 9ZT, 9ZW, 9ZX. 9AEU, DAVID CITY, NEBR., June 18 to Aug. 19. 5AL, 5AO, 5BT, 5CD, (5YH), 5ZL, 5ZP, 5ZV, SCF, &8DC. SER. 8GB, 8IK, 8RB, 9AT, 9AU, 9BR, 9CA 9EL), 9EW, (9FP). (9HT), (9IF), (9KO), (9LR), 9NQ, 9OX, 9QJ, 9QM. ORY, 9SC, 9SY, 9VE, I), 9¥YD. 9YO. 9YP, 9ZN, (9AEG), (9AEQ), 9AFX), 9AIN, 9AJS, 9AJX, 9AJY, 9ALO, (9ANF). 2DX, SUMMIT, N. J. 1AW. 1BH, 1DN, 1JN, 1LY, 1QN, 1TS, 1HAA, IRZ. 1GY. 10A, 1BBL, 1CCL, 1CK, 1DA, 2CG, ‘OR. 2ADJ (fone), 83HJ, 3BB, 8EW, 3BE, 3CK, CV. 38ZA. 3ZS, 3MS. 3LZ. 3LY, 3EN,. 3HG. 3KM, Sat’. 8BO. SDA, 8DW, SER, SEN, 8GB, 8HF, 8MT, SNS. WG, OWY, SXK, 9ZN.

Oscillation BOW a SNAG? é <<, 1525 N. Fawn Street, PHILADELPHIA, PA. Prausformers TELEFUNKEN PANCAKE TYPE Double “A” Quality. Bulletin C-105 on Request Radio Equipment Company

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APPARATUS Type Z.R.V. Variometer has unit A combination of beauty and construction with bakelite shell convenience. Detector panel has ; plug connection which takes your and hard wood ball. Has low regular phone tips. One stage dielectric losses and a range of amplifier has binding posts for inductance of 1.25 mil henry connecting two as a two stage amplifier. All binding posts on xl o .1 mi enry mini- ° maximum t 1 mil henry mini detector, amplifier and Regener- mum. Is readily used on table or ative set correspond for jumper mounted on panels. connection. Complete with 3" dial and knob. . $6.50 Tube Centrol Detector Panel, Z.R.D. $12.00 Without dial or knob . . . . $5.75 One Stage Amplifier Panel, Z.R. A. $18.00 Z.R.F. Regenerative receiver consists of two Z.R.V. Variometers and a coupler of similar construction, together with grid condenser and grid leak with bakelite panel, machine engraved. It exactly matches our Tube Control and Amplifier panels with which it may be harmoniously used. Its range of wave length is 175 to 600 meters. Price. . . $38.00 Co-operate with your local dealer by helping him to carry a stock of Clapp-Eastham Co. apparatus, famous for iis reliability during 13 years of continuous manufacture. -If he doesn’t carry our instruments send 6c stamps for our complete catalogs. CL APP-EASTHAM CO., 114 Main St., Cambridge, Mass. ALWAYS MENTION QST WHEN WRITING TO ADVERTISERS 53

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THE “CCOTIE” WIRL KEY A “Knock-Em-VDead” Beauty as one of our customers named it. Thousands in use in every radio district. Will handle 1 K.W. satisfactorily. The “Cootie” key is the snap- piest sending device offered on the market for reliable spacing of characters. Listen to 9NV, 9LU, 9MS, 9UG, 9BY, and judge for yourself. Larre standards, formica knob, substantial silver con- tacts suitable for use up to 2KW. The double action of the “Cootie” key lends an individuality to your sending. PRI EXCLUSIVE REPRESENTATIVES AT | MANBATT An a ee _ “= AN ELECTRIC SUPPLY CO. YOUR DI R “ a 114 South Wells St, Chicago, Ill.

R adio District 3rd Radio District BERG COMPANY 4 RADIO ENGINEERING COMPANY 428 Mark. San Francisco, Cal. 827 Madison Ave., Baltimore, Md.

5th Radio District ROSE RADIO SUPPLY CO. Radio District YBERG COMPANY

428 Market San Francisco, Cal. 604 Gravier St., New Orleans, La. nr i \ & Manwfactarecs’ =4 vou ‘Combs = Money - back | Dist: ibators Guarantee SS | pogk EST DP Radie Supplies L_Jit | pmogk 18 LA < not ‘ salesroom, send at once for our latest bulletin. . “ x kK “ CENTRAL RADIO COMPANY, Inc. 7 w 513 W xington Street, Independence, Mo. ons y NINE MILES FROM THE HEART OF KANSAS CITY ° CENTRAL CENTRAL RADIO CENTRAL RADIO CENTRAL RADIO CENTRAL RADIO Xe

54 ALWAYS MENTION QST WHEN WRITING TO ADVERTISERS

a lil a a. a

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ALWAYS MENTION QST WHEN WRITING TO ADVERTISERS TE a. 899 BOYLSTON ST. NSTiTw BOSTON, MASS. FALL CLASSES!!! In addition to the splendid radio equipment now in use at the EASTERN RADIO INSTITUTE we wish to announce that we have just added— A COMPLETE NEW 2 K.W. FEDERAL ARC TRANS- MITTER. THIS IS AN EXACT DUPLICATE OF THE HUNDREDS THAT WILL SOON BE IN USE ON VESSELS OF THE U. S. SHIPPING BOARD. Now is the’time to take instruction at an Institute where the very latest spark and arc receivers and transmitters which you will actually use on the ships are at your disposal. When you take into consideration that the Institute was founded in 1913 and has specialized in the training of Wireless operators for over seven years we feel that we know how to give the student proper training. Our graduates may now be found all over the world as Chief operators, Chief radio inspectors, Engineers, Superintendents, Directors of corporations, etc. The number of students to whom we have given instruction at this date numbers over four thousand (4000). Remem- ber—We have actually enrolled, graduated and placed more Commer- cial operators than ALL the Radio schools in New England combined!! If you are considering taking up Commercial radio why not let us train you? Our rates of tuition are reasonable and it costs you no more to avail yourself of our YEARS of RESULTS and SUCCESS. Just remember—We have trained thousands of satisfied students before you and have placed ALL our graduates in good positions. What we have done for them we can do for you. DAY AND EVENING CLASSES, START ANY MON- DAY. WE EARNESTLY URGE YOU TO MAKE EVERY EFFORT TO JOIN THESE CLASSES AS RADIO TO- DAY OFFERS A VAST FIELD FOR ACHIEVEMENTS AND SUCCESS. Our latest, illustrated prospectus giving you complete information is yours for the asking. If there is any further information I can give you just drop me a line or come in and see me. Co-operatively yours, F. D. PITTS, Director. Series No. 3

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Radiophone Music From ALA —— WITH THE C. R. L. PARAGON! C.R.L. Paragon Short Wave Reg. Receiver. f July 26th, L. J. Simms of station KBC, Billings, Montana, copied radio tele- phor m Alaska, using our famous C.R.L. Paragon and Amplifigon combination! And this C.R.L. Paragon can do for your relay work this winter! mn can now be used to received long wave time signals. Watch for our an- nour gon Time Adapter next month. rt Wave Regenerative Receiver, F.O.B. Chicago—$55.00. ginal Armstrong U. S. Patent No. 1,113,149 and U. S. Application Seria] No. CHICAGO RADIO LABORATORY 5525 Sheridan Road (Testing Station 9ZN) 1316 CARMEN AVE, CHICAGO, ILL., U.S.A. YOUR “VT” WILL NOT WORK EFFICIENTLY WITHOUT A GOOD GRID CONDENSER D.H.E. grid condenser is moisture proof. Has copper foil plates and mica dielectric ted in bakelite. Size 2%” long, %” wide. D. H. E. SPECIAL GRID CONDENSER - - $1.25 ‘ARAGON RHEOSTATS~ - - - - - 1.75 VT's $ We « » complete line of standard radio equipment. Prompt attent en all inquiries and orders. DOUBLEDAY-HILL ELECTRIC CO. RADIO DEPT.—DESK A 715 12: W., WASHINGTON, D. C. 719-21 Liberty Ave., PITTSBURGH, PA. REMEDIATE DELIVERIES LEADING MANUFACTURERS PRODUCTS WESTERN RADIO ELECTRIC COMPANY ESTABLISHED OR BETTER SERVICE TO THE WESTERNER” 550 South Flower Street, Los Angeles, Cal. 56 ALWAYS MENTION QST WHEN WRITING TO ADVERTISERS eee ~~ the

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RADIO APPARATUS Distributors of Reliable Radio Apparatus for Schools, Colleges and Experimenters in Every Branch of the Radio Field REMEMBER! We carry an “PITTSCO” The Sign of Service! All we ask is a trial! eee Immense Stock. | Order Today! ANTENNA WIRE “B” BATTERIES ' No. F-1 7 strand tinned copper per foot. $0.01, No. P-1 Standard 22.5 V small.......... $1.40 500 ft. or more per foot.......... Ol No. P-2 Standard 22.5 V large.........- 240 No. F-2 No. 14 Hard Drawn copper wire No. P-3 Standard 22.5 V large per Ib. (80 ft. to the Ib.)........ -60 variable type.......--sseseeeceeeee 3.25 . . No. P-4 45V Everready flash-light battery. 3.50 ANTENNA INSULATORS No. P-5 Everready 22.5 V. small......... 2.25 No. 02 4 inch Electrose insulator.........$0.50 No. P-6 Everready 22.5 V. large.........- 3.50 No. 03 10 inch Electrose insulator....... 1.00 | ©. 05 3 inch porcelain strain type 15 JACKS (Federal) GROUND EQUIPMENT No. 1421-W open circuit.........+++++- $0.70 No. G-1 100 Amp 600 V. Lightning switch .$4.50 No. 1422-W Closed circuit.........+++:+- .85 No. G-2 No. 4 weatherproof ground wire No. 1423-W 2 circuit. ........-seeeeees 1.00 ; Es eects ee ee ee Ohh wa tee -© & A 10 No. G-3 Porcelain knobs with screws complete to hold ground wire....... .12 PLUGS No. G-4 Ground clamp..............+.+; .25 No. WE. Western Elec. brass........--- $1.20 : No. 1428-W Federal Brass...........+++ 1.95 AMPLIFYING TRANSFORMERS No. 1428-W Federal silver plated.......- 2.45 No. A-2 Acme unmounted.............. $4.50 No. A-2 Acme semi-mounted............ 5.00 SPAGHETTI TUBING No. A-2 Acme mounted............... 7.00 No. F-1 Yellow, large, per ft.........+++- $0.15 MODULATION TRANSFORMERS No. F-2 Black, large, per ft..........++.+ o Ne. A-3 Acme wnmounted............ $4.50 No. F-3 Black, small, per ft.........++++ . No. A-3 Acme semi-mounted............ 5.00 POO. AnD Aowmss MUMMIOG. 20. cece cccccses 7.00 GREBE DIALS C.W. POWER TRANSFORMERS NO PDA 4” 0-100. ......-5--eseeeeeees $3.00 No. PDB 4” 0-50... 2... cence ceeenseces 2.75 Acme 200 Watt unmounted............ $16.00 Oe CE: OE Rn os wid atneltn a 2.50 Acme 200 Watt mounted.............. 20.00 ~~ “~~ =~ ahaa pes esr: Acme 50 Watt unmounted............. 12.00 ee et Hy ; bakelite Acme 50 Watt mounted......... hee 15.00 (These Gale are genuine nae RHEOSTATS CONDENSERS (Balanced) No. AM Paragon Back mounting...... $1.75 No. F-800 .0006 Mf. unmounted........ $ 7.50 No. R-2 Remler Back mounting......... 1.75 No. F-800A .001 Mf. unmounted........ 9.50 No. GR General Radio Back mounting.... 2-50 No. F-800B .0015 Mf. unmounted....... 11.50 VACUUM TUBES No. 1 Moorhead Electron Relay..........$6.00 REGENERATIVE RECEIVERS No. 2 Moorhead Amplifier.............. 7.00 No. CR-1 Grebe 160-600 meter with No. 3 Moorhead Transmitting........... 7.50 audion control self-contained....... $90.00 No. 4 DeForest Rectifying tube for No. CR-2 Grebe 160-600 meters........ 51.00 Wireless Telephone work...... occe 148 No. CR-3 Grebe Special 160-600........ Ss No. CR-4 Grebe 160-600 meters........ . VACUUM TUBE SOCKETS a 7 Pams.. G BREES oc cna on ap ote 6 ewe 08 $1.00 OO. R-BED De Oreee. occ cccescccvcvcesce 1.50 TELEPHONES , No. R-400 DeForest gooseneck type...... 2.75 No. B-1 Brown 4000 ohms English _ eS Re Ty eee 1.50 Type_ supersensitive............++. $20.00 No. GR General Radio............... ae No. B-2 Type E Baldwins (Latest)..... 18.50 No. B-3 Type C Baldwins Navy eine 16.50 STORAGE BATTERIES No. B-4 Brandes Superior 2000 ohms. aan No. BX-3 Harvard 6V 40AMP-Hrs.. ... .$18.00 No. 55 Murdock 2000 ohms..........-- 4 No. BX-5 Harvard 6V 60AMP-Hrs...... 21.50 No. 55 Murdock 3000 ohms............ 5.50 (Keep this page and watch for next month’s) SEND 6 CENTS IN STAMPS FOR NEW CATALOG ! F. D. PITTS CO., INC, 12 PARK SQUARE, Dept. A, BOSTON, 11, MASS., U. S. A. ALWAYS MENTION QST WHEN WRITING TO ADVERTISERS

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H Three St shown, >} than pre Style 43 Plates 23 “ 18 These schoo will ne« “listen Th from pre sold at cheapn« ment ti carefu We Naval length anything Patent which } spring 1 the t set. ar the plate any The p and wi adjustme mounte : you car We gener Kindly no lowest the sole G. F. JOHNS s THE “ILLIN¢ EE VARIABLE CONDENSER 1 Aluminum Plates No. 2. Open Type as sea Anti Profiteer. Less assembled and tested. n Receipt of Price. Money back if not satisfied. Justreturn 15 condenser within 10 0 days by insured P.P. additional. e by a watch mechanic manship. Personally we Amateurs who have and “weather” from 9ZS. xO YOU DO IT” ers say. They infer, probably, that anything bear all the earmarks of | to receive an instru- honor”, and above all isted ratified to hear from a would rather wait any “ILLINOIS”, than take Enough Said. “Star Spring” feature, le. The action of this ing friction that holds n to which it may be e automatically centers h other, and prevents relation by construction any necessity of re- always right Once ere is one thing that er give you trouble. nds for their letters of Catalog, and make et our prices at the “middle man” out for smer”’. Black Ave , Springfield, Il WILCOX Type 101 Panel Switch A beautiful and efficient rotary switch for general use. Furnished in two sizes. 1” radius brass finish 40c. Nickel finish 50c. 1%” radius brass finish 50c. Nickel finish 60c. Type 102 Panel Switch A compound switch consisting of two electrically in- dependent switches mounted with concentric knobs. 14%” radius brass finish $1.10. Nickel finish $1.25. Type 103 Panel Switch A rotary panel switch which is double pole and double throw. Will change variable condenser from series to parallel, etc. 14%” radius brass finish 75c. Nickel finish 85c. Type 104 Panel Switch A complete unit for back of panel mounting. The latest and best in rotary panel switches. Better looking, more efficient and easier to mount. Complete with Type 116 Dial and 6 contacts $2.25. Complete with Type 116 Dial and 11 contacts $2.50. Switch Contacts Threaded shank contacts with heads 4"x%”—14 other styles in our catalog. No. 112E Brase 2%4c. No. 112F Nickel 4c. Type 116 Indicating Dials Of polished hard rubber accurately engraved, filled with brilliant white, furnished complete with knob and bushing to fit 4” shaft. 90° scale 0-50 or 180° scale 0-100. 2” diameter $1.25. 3” diameter $1.50. Type 5A Variometer Parts Set No. 1 contains carefully turned wooden parts including winding form. Price $2.50. Set No. 2 contains all parts including 3” Type 116 Indicating Dial. Price $5.00. Type 14A Rotary Gap The best gap on the market. Belt driven, well quenched, clear tone and high efficiency. Price $10.00. All Prices Postpaid All of the above and other WILCOX PRODUCTS are described in our catalog. Sent for 5c. THE WILCOX LABORATORIES Manufacturers LANSING Dept. H MICHIGAN Best of cra el in Radio Apparatus and Parts. Send Stamp for Catalog “Q” J. H. BUNNELL & CO. 32 Park Place, New York Te Bowling Let us just tl and or cal Attention Amateurs ! UTTMARK’S NAUTICAL ACADEMY RADIO INSTITUTE 8079 8 State Street, New York City. you for your first grade commercial license. We have of course you have been looking for. Modern apparatus ed instructors. Day or evening classes. Write, phone ir illustrated prospectus. UTTMARRKA’S for Navication 58 ALWAYS MENTION QS T WHEN WRITING TO ADVERTISERS

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aeueeeeeeene eee ee orders the day they arrive. association being co-operative you will participate in a division of its profits Remit the catalotue price of any standard equipment advert sed else- brings details. where in this magazine for trial order. lines we can supply promptly at a saving. AMPLIFIERS RE Ba. ove eet ences $13.00 Chicago Lab., 1 stage.......... 28.50 Chicago Lab., 2 stage.......... 55.00 i... & ¢ Se ie 70.50 SE PEE EOF EE CT 25.00 NY re eee 50.00 EE, GIS 6 ww cic bio ccns 27.50 i 2 Mis 500m cos oes. 50.00 Radio-Craft, 2 stage........... 50.00 AUDIONS Audiotron 2 filament tubes. $ 6.00 Moorhead detector tube........ 6.00 Moorhead oscillator ........... 7.00 Moorhead transmitter.......... 7.50 Western Electric detector...... 10.00 Western Electric oscillator... .. 18.00 BATTERIES, Storage. Marko, 4 volt 40 A.H.......... $10.75 Marko, 4 wolt 60 A.H.......... 14.50 Marko, 6 volt 40 A.H.......... 16.25 Marko, 6 volt 60 A.H.......... 19.00 Marko, 6 volt 80 A.H.......... 24.00 Marko, 4 volt filament special... 7.25 Marko, 6 volt filament special... 10.45 CONDENSERS, Variable. A.R.CO .005 panel mount...... $ 5.00 AR.CO .001 panel mount...... &.25 DeForest .0005 panel mount.... 6.25 DeForest .001 wernier......... 17.10 DeForest .0015 vwernier........ 18.75 DeForest .00C5 unit mount..... 7.75 DeForest .001 vernier unit...... 18.60 DeForest .0015 vernier unit.... 20.10 Murdoc!: .001 encased....... 4.75 Murdoc!: .001 interior......... 4.25 Murdock .0005 encased........ 3.75 Murdock .0005 interior........ 3.25 Chelsea No. 1 .©91 encased..... 5.00 Chelsea No. 2 .0006 encared.... 4.50 Chelsea No. 3 .001 panel mount.. 4.50 Chelsea No. 4 .0006 panel mount. 4.00 CONDENSERS, Transmitting. Acme, .0035 oil immersed...... $32.00 Acme, .007 oil immersed....... 35.00 Murdock, .0017 moulded section. 3.25 Murdock, .002 moulded sections.. 5.00 CO-OPERATIVE RADIO BUYING Co-operate with thousands of other amateurs. source and get immediate delivery in one package on all your radio needs. In addition to service Buy your equipment from a single We fill This Stamp we will save you money. Space permits us to list a few of the many COILS, Form wound. DeForest (DL) Radisco SG SS ~ | eS $0.70 No. 35 1.70 No. 50...... 1.75 a ms gbte - me, 98... ck 1.05 No. 175..... 1.15 No. 100 . a. SLUR 1.40 No. 150 2.10 ee, es cwds 1.65 No. 250 2.30 No. 750. _ No. 300 245 — — No. 400..... 2.60 No. +++ 2.665 No. 500 2.75 No. 600 ..... 3.05 With taps ). 3.30 No. 1000 3.55 No. 325/3 ...$1.70 No. 1250 3.85 No. 7500/3... 2.30 No. 1500 4.10 No. 1200/3 .. 2.90 COIL MOUNTINGS DeForest, triple adj. unmounted. . .$10.00 DeForest, triple, oak base......... 13.00 DeForest, triple, unit base........ 10.75 DeForest, single, unit base........ 2.00 DeForest, double unit base........ 4.80 DeForest, triple unit base......... 5.60 Somerville, coil holders........... 1.50 Radisco, 3 coil sliding mount...... 6.00 DETECTORS (Cabinet) Ame, audion detector........... $10.00 Chicago Lab., with 1 stage........ Chicago Lab., with 2 stage........ Chi ago Lab., with 3 stage........ 125.00 Chicago Lab., audion control...... 16.00 Chicago Lab., VT-Tron control.... 25.00 DeForest P4C) without cabinet.... 12.00 DeForest P401 with cabinet....... 14.25 DeForest P500 ultra control...... 25.00 DeForest P300 with 1 stage....... 75.00 Mignon audion control........... 22.50 Precision control cabinet......... 22.50 Tresco, VT-Tron control...... ete Se Radio-Craft, audion control....... 20.00 Grebe, RORA Audion control..... 12.50 Grebe, RORH Audion control..... 17.00 Grebe, RORH with batteries...... 19.00 MUTUAL PURCHASERS ASSOCIATION Dept. O, 2 &: 4 Stone Street, New York ALWAYS MENTION QS T WHEN WRITING TO ADVERTISERS

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AS NECESSARY AS A VACUUM TUBE is a B”’ Battery—one that gives dependable sen plenty of it—backed up by the guar- ante dealer who sells it to you. Tl NDARD VT BATTERY” incorporates all 1 sirable features—the secret why you, Standard VT Battery like , will go back to your dealer for an- Cat. No. 7623 othe \NDARD VT BATTERY” and refuse . Price, $1.35 A development originating from the principle employed in the “VARIABLE J STANDARD VT BATTERY,” these Miniature Jacks and Plugs are being put to hundreds of practical new uses all the time. Ask to see them at your Miniature Jacks and Plugs dealer and perhaps you will want a few - for use with that new idea or plan of Price —$1.50 per dozen yours. RICHTER-SCHOTTLER CO., MeErs. 198 Roebling St., (DEALERS—Write for discounts.) Brooklyn, N. Y. PACENT ELECTRIC CO., Sole Eastern Agents, 150 Nassau St... NEW YORK CITY Study Wireless or Learn Telegraphy 1 Boylston St. = } STUDENTS Cer. STON Enter BOSTON ANY TIME Results and Positions Guaranteed Send for free literature. Best ipped Radio School in New England. There has been a Telegraph School at 18 Boylston Street for over 18 years. AMATEUR CLASS STARTS OCT. 15th, 10 A.M. OUR SLOGAN: Better Operators—Not More Operators MASSACHUSETTS RADIO AND TELEGRAPH SCHOOL Tel. Beach 7168 G. R. Entwistle A. R.R.L. pe a THE RADIO TELEPHONE SHOP set yours, and be recog- announces the new zed as a member of the eague. Ready for prompt “PEN” BRAND GRID CONDENSER ipment, im extra heavy led gold and black enamel, Rigidly constructed of the best grade Bake- e $1.50 postpaid. Speci- lite, mica, and copper foil. Particular attention has been paid to workmanship and appearance, and its efficiency is positively guaranteed. Price $1.00—from style desired, pin or ton Address a ths The American your dealer or direct. Radio Relay League, Inc. A Circular for the asking. - at HARTFORD, CONN. 175 Steuart St., San Francisco. 60 ALWAYS MENTION QST WHEN WRITING TO ADVERTISERS

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KADIO-CRAFT PRODUCTS RADIO-CRAFT products set a new high standard of quality in radio apparatus- RADIO-CRAFT laboratories have spent months in perfecting and standardizing their products before placing them on the market. RADIO-CRAFT instruments are thoroughly tested before leaving our plant and bear our absolute guarantee. RADIO-CRAFT purchasers will acquire apparatus of perfect utility, precision, and beauty. DETECTOR AND TWO-STAGE AMPLIFIER TWO-STAGE AMPLIFIER Size:—8%" x8,” x 4” Size:—82"’ x 6” x4” Price $70.00 Price $50.00 The RADIO-CRAFT panel design is followe:, allowing immediate inspection by simp’ snapping out the panel. Continental Radio & Electric Corp., N. Y. C. Manhattan Ele-trical Supply Co., N. Y. C. Kelly & Phillips, Brooklyn, N. Y. Radio Distri>uting Co., Newark, N. J. Philadelphia School of Wireless, Philadelphia, Pa. "AcCarthy Bros. & Ford, Buffalo, N. Y. Rudolph Schmidt & Co., Rochester, N. Y. DETECTOR American Electro Technical Appliance Co., N.Y.C. Size:—74," x 4%4"" x 344” Price $15.00 RADIO-CRAFT CO., INC. BROOKLYN, N.Y. Jobbers’ inquiries concerning our distributing proposition are invited. ALWAYS MENTION QST WHEN WRITING TO ADVERTISERS

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CHELSEA VARIABLE CONDENSERS (Die Cast Type) No. 1.—.0011 m.f. mounted No. 2.—-.0006 m.f. mounted No. 3.—.0011 m.f. unmounted. . No. 4.—.0006 m.f. unmounted Top, bottom and knob are genuine P bakelite, shaft of steel running in STE bronze bearings, adjustable tension on CC(((((( (f movable plates, large scale reading in AA hundredths, high capacity, amply separ- ated and accurately spaced plates. ti} Unmounted types will fit any panel , and are equipped with counter-weight. 3 Spark Load Coil Rai 3500 meters. Taps are in geomet! ession, permitting exceptionally fine tur | the longer spark wave lengths. Ten a ictance steps. Base and knob moulde All " apparatus embodies highest de- gree n onstruction, electrical efficiency and go rance., Pur from your dealer; if he does not INDUCTANCE carry it to us. Catalog sent upon request. Price $3.50 CHELSEA RADIO CO., 15 Fifth St., Chelsea, Mass. Manufacturers of Radio Apparatus and Moulders of Bakelite. ‘ —— 66 99 BURGESS'B)| | | “COSRADIO BATTERIES - a aaieeniliaa aaa SEVERAL SIZES Do you want a real honest-to- FOR oe goodness transmitter? Write now before it is too late. WORK & Transmitters. Receivers. SPECIAL | A proposition to every radio man. Amplifiers. Detectors. Senp FOR. CATALOGUE Amrad—Radisco Agents. BURGESS BATTERY en an le ert ee COMPANY THE COSRADIO CO. HARRIS TRUST BLDG.- CHICAGO, ° on Wichita, Kansas —— — Colorado Springs, Col. ALWAYS MENTION QS T WHEN WRITING TO ADVERTISERS

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A Combination that Can’t be Beaten x | | For Results,—real long-distance signals on short wavelengths you can’t beat the Relay Receiver (Type CR-3) and Detector and 2-Stage Amplifier (Type RORD) This is the Outfit which made a reputation for itself in the recent QSS tests. You can get into the Big Relay Game and become one of the dependable long-distance men with this Outfit. Inspect this Outfit at your Dealer’s. If he doesn’t carry our line as yet, drop us a postal for catalogue, mentioning his name. GREBE RADIO apparatus is licensed under the original Armstrong and Marconi patents. Central Radio Institute, Independence, Mo. Manhattan Electrical Supply Co., New York, Continental Radio and Electric Corp., New York Chicago, St. Louis Doubleday-Hill Electric Co., Pittsburgh, Pa. Leo. J. Meyberg Co., San Francisco, Cal. Holt Electric Utilities Co., Jacksonville, Fla. Pacent Electric Co., Inc., New York City Hurlburt-Still Electrical Co., Houston, Texas. F. D. Pitts Co., Inc., Boston, Mass. Kelly and Phillips, Breoklyn, N. Y. Phila. School of Wireless Telegraphy, Phila., Pa. Klaus Radio Company, Eureka, IIl. Western Radio Electric Co., Los Angeles, Cal. | A. H. GREBE & CO., Inc. | 74 Van Wyck Blvd., Richmond Hill, N.Y. | ALWAYS MENTION QS T WHEN WRITING TO ADVERTISERS 63

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“SHRAMCO” Specialties are needed for an efficient set Switch Points x 3, ; with head, %” shank, with nut and washer \” with screw e Knob, Phosphor Bronze Blade, With Bushing, radius ; e Blade, 1%” radius, brass finish Binding Post, brass finish Brass Binding Post, brass finish, screw and washer... . mplete line reliable moderate priced apparatus. Agency, Coils, “B”’ Batteries, Dial Indicators, etc. oad Sc in stamps for Catalog J showing complete line. Shotton Radio Manufacturing Company P. O. Box 3, SCRANTON, PA. RAPHAEL | Strom Y too F= WE HAVE IT. mand and increased cost of Chart of code and Q abbreviations, change our policy in regard to these Charts which will now be r of $1.00 or over. ELECTRIC CO., PITTSBURGH, PA. 1405 Sth Ave. “PW” Has The Latest Radio Apparatus In Philadelphia me in and see Us—You do not have to Buy. nave parts for the Radiophone you are building. Philadelphia School of Wireless Telegraphy ALWAYS MENTION QS T WHEN WRITING TO ADVERTISERS

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t Announcing the New 1921 Model RED HEAD RADIO RECEIVERS A Triumph in Radio Phone Building The Famous ARLINGTON TESTED CRYSTALS The Acknowledged Standard in Radio Detector Minerals. It has been said by advanced radio physicists that vacuum tubes are no more sensitive than “very good” spots on galena. Hundreds of testi- monials now in our files testify to the probability of such a_ statement. These letters comd from users of Arlington Tested Crystals. Arlington Tested Minerals have been on the market seven years and are sold by reputable dealers everywhere. Each crystal is individually tested and boxed in a litho- graphed metal container. Imitations are available but you can be assured of the original genuine crystals by looking for the signature “J.S. Newman” on each box. NAA Tested Galena... .35c NAA Tested Silicon... .35c Postpaid MAIL ORDER SERVICE Our mail order department is prepared to make practically im- mediate shipment on all radio ap- paratus of the following standard makes DeForest Thordarson Murdock Acme Signal Mignon Amrad an Bunnell many others Mail your orders to us and be assured of real radio service. The new “Red Heads” are Ready. Rugged and sturdy as ever- but even more exquisitely sensitive. The same handsome appearance -but wound to a higher resistance. The same guarantee - WE, not you, as- sume the risk. For five years Red Head Receivers have held an enviable position in the radio field. The new models popularity. Detail: 1500 ohms each receiver (3000 ohms per pair); cast aluminum backs; genuine Bakelite ear caps, re-inforced cords with strain loops and posts; phosphor bronze head bands. Money refunded if Red Heads don’t please’you. will maintain their PRICE, prepaid anywhere, $12.50 complete set Catalogues Free on Request THE NEWMAN-STERN CO. 1874-76 EAST SIXTH STREET, These Distributors can supply “Red Heads’”’ Signal Electric Co., Menominee, Mich. Lee DeForest Co., San Francisco, Cal. EASA RT TR TT ALWAYS MENTION QS T WHEN WRITING TO ADVERTISERS CLEVELAND, OHIO to Dealers and Experimenters. DeForest Radio Tel. & Tel. Co., N. Y. J. H. Bunnell Co., New York 65

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ACME is now synonymous with Transformers and is coming to be synonymous with CW increased sales of ACME APPARATUS is of of its efficiency, attractiveness and service Our growth has been on the merits of our apparatus ACME APPARATUS CO. 2ManDSOR STREET Radio Electric Adapters Postpaid - - $1.50 PITTSBURGH AMATEURS and others are in- vited to call at our new store and inspect the latest radio instruments. Send 10c for our new catalogue. “We make or sell Everything Radio” The Radio Electric Company 3807 Fifth Ave., Pittsburgh, Pa. Audion Control Unit Only $13.75 The K. & G. Wireless Supply Co., in its efforts to place technically correct and reliable wireless apparatus well within the price reach of critical amateurs, announces its new Audion Control Unit, Type Al. This new unit is absolutely reliable and can be used with every known circuit. It is designed and built for exacting service. It combines the very latest ideas in design with the best of material and workmanship. The cabinet, 8x5%x6”", has a highly polished mahogany finish and with its well mounted bakelite panel will add much to the attractiveness of your station. The unit contains these instruments: vacuum tube socket (for standard 4-prong tube) fila- ment rheostat (10 ohms), grid condenser, grid leak, and filament switch. Panel has binding posts, suitably engraved in white, for secondary, tickler, phones, and filament battery. Whole back of eabinet swings open on hinges and thus permits easy insertion of tube and batteries and complete inspection of the interior. Efficiency guaranteed, or money refunded. Price $13.75, without tube or batteries. dealer can't supply you, order direct. Dealers: Write for proposition. K. & G. WIRELESS SUPPLY CO., Dept. 18D, 152 Chambers Street, New York City ALWAYS MENTION QST WHEN WRITING TO ADVERTISERS

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yea; SUA WAKA ae i TS — The Newest Radio Development The DeForest Portable Buzzer ‘“Radiophone Type OT-5 DeForest Oscillion Transmitter (Wireless Telephone). For Automobiles, Motor and Sail Boats, Camps, Surveying and Exploring Parties, Forest Patrol, Farms, and all isolated T >. latest development of the famous places, this new “Radiophone” set offers sure, quick, practical word-of-mouth communication. Operates on two 6-volt storage batteries; no “B” battery or other outside source of high potential is required. Can be easily transported; entire Transmitter, including batteries, weighs less than 60 pounds. Range on ordinary Ama- teur aerial, is 5 to 10 miles, and can be materially exceeded under proper conditions. Operates with any suitable type of Receiver and Audion DeForest Portable Detector; with or without an Audion Amplifier, “Radiophone” Transmitter depending on the range to be covered and loud- Buzzer Type O T - 5 ness of reception desired. e Without Storage Batteries Price Including Vacuum Tubes $ 1 35 OO F. O. B.—New York e Investigate this new DeForest production now. Order at once to insure early delivery, either thru your regular dealer or direct from us. DeForest Radio Telephone & Telegraph Company ino:nators and Manufacturers of High Grade Radio Apparatus 1407 Sedgwick Avenue New York City LEE DE FOREST, Incorporated, 451 Third St., San Francisco, Cal. WESTERN DISTRIBUTORS * “Radiophone” Name Copyrighted. SE E FOREST. 1 ; ALWAYS MENTION QS T WHEN WRITING TO ADVERTISERS

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DEALERS WRITE FOR OUR ATTRACTIVE PROPOSITION s Early for your Rotary Spark Gap. Made either 6 or 12 point $50.90. Rotor only $25.00. Fully Guaranteed. NEW LITERATURE—NEW INSTRUMENTS. w line of audion control and amplifier panels, unit type and a new reasonably priced. Send for literature and also our price list of terials. Wireless Manufacturing Co. Canton, Ohio A DIO ee A Tt Tae OU At Grand Central Palace, Booth No. 207 from October 6th to 16th. GIVEN FREE lete list of RADIO APPARATUS and PARTS, ready, October first. » IMMEDIATE DELIVERIES. Send in your order now, LOW PRICE, UNT to RADIO CLUBS and SCHOOLS. AMERICAN ELECTRO TECHNICAL APPLIANCE CO. et, Dept. B.7, New York City BAKELITE-DILECTO the Standard Insulating Material on all Radio Work proof, permanent, strong, used by all important ifacturers of Wireless Apparatus and others re- ing the utmost in Insulation. Furnished in Sheets, s and Tubes. THE CONTINENTAL FIBRE CO. York Ci NEWARK, DELAWARE S08 So. Michiown Ave. Ill. 411 S. Main St. isco, Cal. Les Angeles, Cal. »| Bank Bidg., Cor. King & Young Sts., Toronto, Ont. 301 Sth Ave., Pittsburgh, Pa. ALWAYS MENTION QST WHEN WRITING TO ADVERTISERS

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The ever increasing demand of the amateur for an amplifier that wil not “howl” when used in multiple stages of amplification, has led us to extensive researches in this field, and through the efforts of our engineers, with the wonderful facilities of our Research Laboratory, we have met with success, and can now offer a thoroughly efficient and reliable amplifier. We are at present, manufacturing these amplifiers in four Standard Sizes as illustrated above. They are constructed of the finest quality material and workmanship, in accordance with the best engineering practises. The cabinets have a polished mahogany finish, and the panels and shelves are of hand finished Bakelite, finely engraved and filled in with white enamel. We are also incorporating in these sets, a special patented indicating device for the resistances, which no other amplifier on the market has. The dimensions of these units are standard and can be added to, from time to time. We are offering these sets to you at the following reasonable prices :-— Type DA-2 Detector and Two Stage Amplifier Type DA-1 Detecor and One Stage Amplifier. . Type A-2 Two Stage Amplifier.... Type A-1 Single Stage Amplifier PRICES—F.O.B. NEW YORK Address all orders and inquires to Dept. ‘ ALWAYS MENTION QS T WHEN WRITING TO ADVERTISERS

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IT Cr G.A ONLY BETTI

GRID BROADWAY SUBWAY TO 18ist STREET ©. A. The General Apparatus Company, Inc. 184th Street at St. Nicholas Ave.,

MAKE IT NEATLY MADE FROM MATERIALS WHICH_IN- SURE PERMANENCE AND EFFICIENCY, THESE CONDENSERS ARE A SUPERIOR SUBSTITUTE FOR EXPENSIVE TYPES. ENSER For every audion circuit the Grid Condenser, of 0.0005 mfd., is the right one ~ 35c eac A 0.0005 mfd. condenser, with an enclosed leak of 1 ——. Replaces each. To shunt around the "phones in crystal detector circuits, and around the 5 battery in audion circuits. By-passes the makes the signals ach to amy part of the United States or Canada, Sc. Sold at all the large stores. STORE CARRIES ALL G.A. STANDARDIZED SUPPLIES AND INSTRUMENTS, New York City

T) It heads eddy atin are } cases justment tem p<« Variat Strongly structed sensitive use on sh aboard Strombe Ca Tel. Mfa Rochest

this Sensitive lio Head Set

We have everything you need. few items from our large stock. th space for a complete stock list. non-conducting spool tips which eliminate Audion Receptacles Furthermore all oper- | DeForest R300

TROMBERG-CARLSON | = er lec Radio Head Sets Murdock No 0 nd 1 s

moisture-proof aluminum B Batteries Standard No. 7623 Standard No. 7625 Standard No. 7650 (Plug and Socket) Binding Posts Radisco Bunnell Mesco DeForest Signal Claprp-Eastham Books Practical Wireless Telegraphy Vacuum Tubes in Wireless Wireless Exerimenters Manual! How to pass U. Radio Instruments and Measurements ...... less Tel. Part 1 and 2 Radio Experimenters Book Sleeper

lletin 1206T gives full particulars. Write Today.

137 East Fifth St.,

The above prices are F.O.B. St Manufacturer's S. Govt. Exams.. Elem-ntary Principles of Wire- ;

A Full Line of Radio Apparatus Below are a Watch this $1.50 ea. 2.75 ea. 1.50 ea. 1.00 ea.

$1.35 ea 2.40 ea 3.25 ea

Price $2.25 2.25 2.25 -75 1.75 1.75 1.25 . Paul. PIONEER ELECTRIC CO. St. Paul, Minn.

ALWAYS MENTION QS T WHEN WRITING TO ADVERTISERS

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“USE THE‘ TUBE THE NAVY USES” ee Ps - = 4 . The U. S. Navy flying boat NC-4 first airship to cross the Atlantic and the A-P VT AMPLIFIER-OSCILLATOR Amplifier used on the trip. A-P TUBES CROSS WITH NC-4 | So efficiently did our A-P VT tubes serve the NC-4 on this trip, so much did they contribute to the success of rig ° ° Used in conjunctio i h : this great achievement, that volun- A-P VT Amplifier-Oselllator. is , | h B f FE ° . f our A-P Electron Relay— tarily the ureau oO ngineering oO price $6, also equipped with he U. S.N | abora- hg Pm ee the U. oS. INavy wrote our Labora eee 8 ee a ? ° ° ° amplifiers with an A-P Electron tories a letter of appreciation. Moly co the twlted detesten oc oscillator is the IDEAL RE- i CEIVING COMBINATION for ‘ long distance amateur or long AMATEURS—“Use the Tube the Navy Uses” wave reception. the A-P VT Amplifier-Oscillator—price $7 equipped with the SHAW standard four- prong base. Order from your dealer. De- scriptive pamphlet free upon request. A-P tubes manufactured under the DeForest Audion and Fleming Patents. Other patents applied for and pending. ATLANTIC RADIO SUPPLIES CO. PACIFIC RADIO SUPPLIES CO. 8 KIRK PLACE- NEWARK-NEW JERSEY 638 MISSION ST.-SAN FRANCISCO-CAL. Distributors for Moorhead Laboratories, Inc. ALWAYS MENTION QST WHEN WRITING TO ADVERTISERS

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Don’t Take Our MURDOCK Word For It NO. 55 What Others Say— ve It For Yourself you to take our word rity of Brandes Matched- Thousands of operators us unsolicited letters siastic over the results Brandes Receivers. Read hem say, then act on our 2000 OHM DOUBLE SET Set, 2000 ohms $7.00 BRANDES $4.50 VMatched-Tone 3000 OHM DOUBLE SET reless Receivers : and more than you $ e 0 be.” W.M.—Columbus, best phones anyone can Maae for long and ne in the stations you ther phones and cut ae Usetu service in ery many receivers and none of them are Radio stations where their ass with yours. Honest pection and testing (pre- nt) ought to be known.” Dependable and sensitive Mass. pair of your 2,000 Ohm O and have used them peration makes them the ears. They are better up messages when failed.” E.H.— Gist of those who N.A.A. much sharper your Superiors than ice GOOD *phones. 1000 Ohms, and they * C.D.—Bellefonte, Pa. ee ge antenna of only 40 tal detector, and my ORDER YOUR SET NOW— > I have been able to 1400 miles at sea Try it out thoroughly. . Pa.” CoM—Oon IF IT DOESN’T SUIT, SEND IT BACK AND GET YOUR Our Offer ’ MONEY atalog “F’’. Order ir receivers you want. _—_—___ lays in comparison with . P have now. If they aren't Bulletin 19 shows a splendid f clearness, sensitive- than what you are line of the type of apparatus = them to oe ane Dot you want. Send for a copy. immediately and with- are used by U.S. ae ee WM. J. MURDOCK CO. all over the world. BRANDES, Inc. 65 Carter St. mare, New York, N.Y., Room 821 CHELSEA MASS. ‘ess Receiver Specialists 221 SECOND ST., SAN FRANCISCO, CALIF ALWAYS MENTION QST WHEN WRITING TO ADVERTISERS

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so Manufacturing reasons make it impossible to con- tinue the present hand- made AUDIO TRON. This type has a double filament of special thorium tungsten and the operat- ing life is over 2,000 hours. No special socket is re- quired. The electrical and mechanical dimensions re- sult in a heavy plate cur- rent and corresponding sig- nal strength. Plate voltage under 40. The few thousand that will still be produced, however, will be of the same stand- ard of excellence that has characterized every AUDIO- TRON. Already recognized as the most sensitive detector on the market, these few that will remain, with all re- Dept. Q, AUDIO TRON Your last chance for an AUDIO TRON ime The Original Tubular Vacuum Detector, Amplifier, Oscillator NOW FREE FROM ALL RESTRICTIONS Dealers and Amateurs ! AUDIO TRONS, recognized as the most sen- sitive detectors ever produced are now licensed under Fleming Patent No. 803,684 for amateur and experimenta] uses only in radio communication. They are no longer limited to radio frequency and can now be used as detectors and oscillators as well as amplifiers. All patent questions have been definitely settled. Vacuum tube patents are basic and have been sustained by the Federal Courts. Be sure to get genuine AUDIO TRONS, they outclass any other form of detector and are absolutely free from all legal restrictions or difficulties. These new uses make it even more necessary to insist on the genuine. You can always tell a real AUDIO TRON by the name stamped plainly on the glass. Insist on the name AUDIO TRON on every tube you purchase. Fully guaranteed by the AUDIO TRON Mfg. Co. (Read the guaranty below). . DETECTOR strictions on amateur use lifted, are undoubtedly the greatest opportunity ever offered to amateur radio operators. See your dealer at once or order direct. Be sure to benefit by this last opportunity to secure a hand-made _ super-sensitive, double filament AUDIO- TRON Detector, Amplifier, Oscillator. $6.00 each (No increase in price) The AUDIOTRON Exclusive Guaranty: Each and every AUDIO TRON is guaran- teed to arrive in good con- dition and to prove fully satisfactory. Replacement of unsatisfactory tubes will be made free of charge. Lick Bldg., g tan Get in touch with the AUDIO- TRON Mfg. Co. at once. We will give you full information about settlement of all patent difficulties. You will also be interested in our new proposition for wide awake ers. After the present supply is ex- hausted, new types of AUDIO- TRON, manufactured entirely by machinery, will be offered for sale. Our extensive advertising during the Fall will establish definitely the superiority of the AUDIO TRON and will create new sales for you. Be sure to take advantage of our full co-operation at once. Prepare to cash in on the AUDIO TRON | reputation, established since 1915. Write us today for full details. AUDIOTRON MFG. COMPANY (Successors to the AUDIO TRON Sales Co.) San Francisco, California ALWAYS MENTION QS T WHEN WRITING TO ADVERTISERS 73

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| Therma -Ammeters, Milliammeters and Current-Squared Meters SSvONn Model 425 Miniature Size Instruments for Radio Service are the ideal Instruments for the amateur. They are particularly adapted for use on small size Radio panels where space is an important factor. Their characteristics of accuracy, large over- load ca mall current consumption and small size make them particularly desirab on amateur and other low-power outfits. TI for use on Audio and Radio frequencies. C nformation will be furnished upon request. Weston Electrical Instrument Company 158 Weston Avenue, Newark, N. J. Branches in all Principal Cities. DO YOU MAKE A RAPID TURN- DEALE RS OVER ON YOUR SMALL PARTS ? AND CONSTRUCTION SUPPLIES ® EVERYDAY ENGINEERING MAGAZINE SOLD at tore will increase your business im switch points, knobs, amplifying transformers, rheostats ckets, wire, condensers, jacks and plugs, and similar supplies. Every exp: who buys a copy of Everyday Engineering sees in it articles on radio apparatus, not made but the kind of parts which you carry and want to sell. If a man b © magazine at your store, he will go back to you for supplies to build the instruments he finds described—and the articles are so — selected and prepared that he can't help wanting to make ti apparatus shown each month in Everyday. Also, the descriptions of new things from the manufacturers help to sell your other equipment. You, teo, are invit to send in descriptions and photographs of apparatus you are putting on the market. SELL “EVERYDAY” TO SELL YOUR SUPPLIES AND APPARATUS TO THE CIRCULATION DEPART- MENT TO FIND OUT HOW YOU CAN ? OBTAIN COPIES EACH MONTH TO SELL IN YOUR STORE. WILL You ® EVERYDAY ENGINEERING MAGAZINE Twenty cents per copy, two dollars per year. 2 West 45 Street, New York City ALWAYS MENTION QST WHEN WRITING TO ADVERTISERS

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CLAPP-EASTHAM APPARATUS ROTARY SPARK GAP No. 741 This Rotary Gap comprises a substantial iron cast- , finished in black, which completely encloses the spark- largely eliminating the objectionable noise of the spark and removing the blinding flashes which are injurious to the eyes. The motor for driving the rotating element is of the highest grade variable speed, series wound motor obtainable and, unless otherwise speci- , is wound for 110 V AC 60. All electrodes are of pure rotating member being patterned something after a circular saw, rotating backwards so that there is an instantaneous break and ro tendency for the spark to Variations of from approximately 2000 to 6000 rpm are possible and the rotor has sixteen teeth or sparking IMPROVED ANTENNA SWITCH No. 658 For the amateur who desires an efficient and smooth working transfer switch we are pleased to recommend the one shown in the accompanying cut. This switch may be used to transfer the antenna from the receiving to the transmitting apparatus and when in the latter position will close the transformer power circuit, ground the receiving set and start the rotary gap. This instrument is of grained bakelite thru-out, all metal parts being finished dull nickel. Price, $12.50 Price, $50.00 BALANCED VARIABLE CONDENSER No. 800 The increasing tendency to- ward compactness of construction in receiving and transmitting sets requires a condenser occupying but a small amount of panel space. Requiring but 3% inches of panel when mounted and being supplied in capacities of .0006—.001 and .0015 mfd. this condenser is especially suited for panel mount- ing. In addition to the above ad- vantages the balanced design of the plates renders its use in a horizontal position possible. The construction is of aluminum thru- out with hard rubber insulating bushings in the top and bottom bearings. This condenser is normally supplied un- mounted with scale and knob. When desired for laboratory use a heavy brass oil- tight case may be obtained at an additional cost of 4.00 dollars. mfd., $7.50; No. F800A, .001 mfd., $9.50; No. F800B, .0015 mfd., $11.50. No. F800, .0006 SEND FOR OUR No. H-12 MANUAL OF WIRELESS TELEGRAPHY You should have it even if only superficially interested. Around about you every day you read of some marvelous occurrence in which wireless played a distinguished part. It may not be entirely clear to you. The Manual will explain it. To the student of Wireless Telegraphy, the Manual contains much that is indispensable to a proper understanding of the art. A good portion of this is now published for the first time—and consists of formulae, tables, diagrams, Federal regulations, codes, diagrammatic -in- struction for installing, maintaining and operating wireless stations, to- gether with a complete list of up-to-date wireless instruments and accessor- ies. The Manual contains 192 pages, fully illustrated on high-grade paper stock with a two-color cover. We ask twenty-five cents ($0.25) for it—give you a coupon receipt which can be applied on any order amounting to Five Dollars ($5.00) or more. Do not wait until some other time, but sit down now and send your mame and address, and get one of the most complete, comprehensive and reliable wireless .pamphliets published. 17 Park Place 114 S. Wells Street 1106 Pine Street NEW YORK CHICAGO ST. LOUIS MANHATTAN ELECTRICAL SUPPLY CO., Inc. “SAN FRANCISCO 604 Mission Street ALWAYS MENTION QS T WHEN WRITING TO ADVERTISERS 75

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| Here’s How! In spite of Prohibition we can still use tl ld expression, to show you tl ur inductance units can bi irchased at just as rea- sonable a figure as any other part of your ipment. There’s just one W buy direct from the manuf rer. Honey-comb coils are né vailable at “direct-to- you” p1 look them over: PRICE UNMOUNTED Any of above sizes will be sent p: | to all points in the U. S. uy receipt of remittance. To av lelay or possible loss remit by Postal Money Order. Coto-Coil Co. 87 Willard Avenue, PROVIDENCE, RHODE ISLAND ws Dp “The Rec ygnized Symbol of Superior Performance A revision of prices September 15, 1920, was required in order to maintain the Amrad standard of quality. Former prices of Amrad Radio Products published in catalogs or bulletins now in circulation should be disre- garded and this list consulted when planning purchases. ARTICLE P Bulletin” Price Induction Coil, 6 volt, Type C........ P-2 $35.75 Induction Coil, 32 volt, Type C-1 Quenched Gap, 1 K.W., Type G-1 Quenched Gap, ¥% K.W., Type G-2.... Quenched Gap, %, K.W., Type G-3.... Quenched Gap Gaskets (each) Resistance, 1 K.W., Type A-1 Resistance, 4, K.W., Type A-2.... Resistance, 4, K.W., Type A-3........ Cabinet and Panel, 5x5x6%,", Type A. . Cabinet and Panel, 10x5x64%,", Type B. Cabinet and Panel, 10x10x10”, Type C. Cabinet only, 47.x47%,x64%", Type A... Cabinet only, 97,x4%x6¥,", Type B.. Cabinet only, 10x10x10”, Type C...... Bakelite Panel, 5x5x%", Type A-1.... Bakelite Panel, 10x5x4,”", Type B-1... Bakelite Panel, 10x10x7,", Type C-1 Cabinet connector with screws, Type A. Panel Brackets, Type A... Knob with dial, 180°, Type A Knob with dial, 90°, Rubber Knob, with screws, Type A.... Bushing for *,” shaft, Type A Dial only, 90°, Type B Panel Switch, Type B Switch Points, each, Type B Binding Post, large, Type H-16 Binding Post, medium, Type J-12 Detector Stand, duplex, Type C Detector Stand, single, Type C-1.. , Detector Contactor and Cup, Type C-2. T Wavemeter, 130-230 meters, Type D..W-1 AAD DWAR AABRADHAHAABABBOLOOOLOOA Operators: Any bulletin desired sent upon request. If you wish our complete catalog and your name entered on our mailing list, send us your dealer’s name and address. Canadians: Send for Canadian edition of our cata- log giving Canadian prices and complete list of Canadian dealers carrying Amrad products. AMERICAN [RADIO AND [RESEARCH (ORPORATION 13 Park Row Factory and Laboratory New York Medford Hillside, Mass. Address all Communications to New York Office. - ALWAYS MENTION QS T WHEN WRITING TO ADVERTISERS

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——— Anticipating the Demand While analyzing the wants of the Radio Man, Radisco discovered the value of anticipating the demand for rn and efficient apparatus; knowing that the Radio Man would be quick to realize and appreciate such service. Under this incentive Radisco engineers have produced such justly famous instruments as Radisco Coils and “B” Batteries and we now take pleasure in an- nouncing the new RADISCO VARIOMETER. Like all other Radisco products it has been produced to anticipate and supply the demand for a good short wave instrument, qualified to stand the acid tests of radio work, and built at a price consistent with the cost of manu- facture, which has always been a Radisco characteristic. For the radio man who desires an instrument of this character, our Variometer makes a distinct appeal. It is made in one size and of one quality, the best. The extreme dimensions are 4%” high, 3” wide, 5’’ deep and the shaft is of 4%” brass, just the right size to fit the number 69 dial; forms are carefully turned from thoroughly seasoned wood and substantial brass bearings provided. The price is strictly an innovation and should appeal to the most conservative. Number 1 Variometer, $7.00 Number 1D Variometer with dial, $8.50 Shipping weight 3 pounds. The agents listed below carry all Radisco products and they will be glad to consult with you on the new Radisco Variometer ALBANY, N. Y. Shetton Radio Mfg. Co., 8 Market Street ASHEVILLE, N. C. Hi-Grade Wireless Instrument Co. ATLANTIC CITY, N. Indepen J. dent = Pre pd Co. ew Jersey Ave. BALTIMORE, MD. Radio Engineering Co., €14 No. Calvert St. BIENVILLE, QUEBEC, CAN. Canadian Radio Mfg. Co. BOSTON, MASS. Atlantic Radio Co. 88 Broad Street BROOKLYN, N. Y. Kelly & Phillips 312 Flatbush Ave. CHICAGO, ILL. Chicago Radio Laboratories, 1316 Carmen Ave. EUREKA, ILLINOIS Klaus Radio Co. Branch, Peoria, Ill. KANSAS CITY, MO. McCreary Radio Supply, 4th & etewens Sts. LOS ANGELES, CALIF. The Wireless $s S511 W. Washington St. McKEESPORT, PA. K. & L. Eleetric Co., 427 Olive Street NEW ORLEANS, LA. Rose Radic Supply, 604 Gravier Street Responsible dealers: NEWARK, N. J. A. H. Corwin & Co. 4 West Park Street NEWCASTLE, PA. Pennsylvania Wireless iy Ce., orence Ave. “sHA” OMAHA, NEBRASKA O-B Radio Supply Co., 406 Brown Building. PHILADELPHIA, PA. Philadelphia School of Wireless Telegraphy Broad and Cherry Streets. PROVIDENCE, R. lL. Rhode Island Elec. Equ Co., 45 Was ington Street PITTSBURGH, PA. Radio Electric Co., 3807 Sth Ave. PORTLAND, MAINE Atlantic Radio Co., : 15 Temple Street SEATTLE, WASH. Northwest Radio Service Co., 609 Fourth Ave. SCRANTON, PA. Shotton Radio Mfg. Co., P. O. Box 3 Branch, 8 Kingsb St. Jamestown, Y. ST. LOUIS, MO. The Benwood Specialty Co. 3424 Olive Street TORONTO, ONT., CAN. The Vimy Supply Co., 585 College Street WICHITA, KAN. The Cosradio Co., 1725 Fairmount Ave. Write Pw interesting ie aadiad proposition on Radisco apparatus If none of the above agencies are in your vicinity, or do not give you the desired information on Radisco Apparatus communicate with | RADIO DISTRIBUTING COMPANY, Se —— eee ALWAYS MENTION QS T WHEN WRITING TO ADVERTISERS Newark, New Jersey

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Baldwin Mica Diaphragm Amplifying Telephone vn in amateur, commercial and government radio circles as Old Baldy Fone”’. super-sensitive phone is required you'll find Baldy on duty, ng communication with stations ordinarily “dead’’. stocked by all reliable radio dealers. Patronize your 3 types C, E and F. 3 Prices. | | Watch for announcements of | new “FIRTH” specialties. JOHN FIRTH & CO., Inc. Radio Specialties of unusual merit. 18 Broadway CRID VARIABLES mfd. variable condenser fills the long felt want for a rugged, low | variable condenser for panel mounting. efficiency are combined with ace high quality of materials and work- new type variable. at : All Parkin variables are sold subject to return within five days if not fully satisfactory. No. 50 }1 mfd. Unit alone, may be mounted on any shaft | mfd. Unit with knob, shaft, and pointer No. 52 | mfd. Unit—complete with 3” black dial e prices include postage to any part of the United States. THE PACIFIC RADIO DISTRIBUTING COMPANY POMONA CALIFORNIA “The Radio Telegrapher’’ Official Organ United Radio Telegraphers Association ROOM 303, 44 BROAD STREET, N. Y. sted on what’s doing among the commercial telegraphers, board At Shore Stations At Home and Abroad. yearly, U. S. and its possessions $2.00 yearly in foreign countries 5S yearly in Canada $0.15 a single copy ALWAYS MENTION QST WHEN WRITING TO ADVERTISERS

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“SIGNAL” RADIO APPARATUS “SIGNAL” ARLINGTON RECEIVING TRANSFORMER No. R22—$11.40 This instrument, which is without doubt the finest Loose-Coupler on the market, has been made in our large factory for several years and handled by distri- butors throughout the country. The woodwork is beautifully finished in dark mahogany. Metal parts are of brass polished and lacquered. The wind- ings are of silk covered wire and are upon specially treated tubes. Secondary variations are secured by means of a 12-point switch mounted on a “formica” front to avoid any leakage. The primary is controlled by a smooth working slider. “SIGNAL” VARIABLE CONDENSER No. R34—Cap. .001 Mfd. $6.00 No. R35—Cap. .0005 Mfd. $5.10 The “Signal” rotary variable condenser has genuine formica ends, a clear glass case, a 4%” shaft and plates .024 thick of a special grade of aluminum. Of these specifications we desire to eall particular attention to the thickness of the plates and to the form of end-piece which is square, and facing the operator. The scales are calibrated to 2% degrees. We also manufacture our condensers for pane] mounting in 11, 21 and 48 plate sizes of the same high grade as our complete condensers. They are so constructed as to permit mounting on any panel from %” to %” in thickness. Each instrument is furnished with a metal scale calibrated to 180°. The knob and pointer are removable by means of a single flat head machine screw. “SIGNAL” (Short Wave) RECEIVING TRANSFORMER No. R32—$14.40 In our short wave receiving transformer the amateur will find the embodiment of all of his ideals. It is designed for use on amateur aerials of from 150 to 200 M. fundamental wave length and with a small capacity variable condenser across the secondary will easily tune to 600 M. The windings are of the very efficient type known as bank wound and are of heavy stranded conductor, in silk sleeving. Variation is obtained by means of a 12-point switch mounted on “formica”. Woodwork has a hand rubbed mahogany finish. All metal parts are polished nickel plate. Secure “Signal” products from your dealer, or if he cannot supply you write our nearest distributor, giving your dealer’s name. SIGNAL ELECTRIC MFG. CO. MENOMINEE, MICH. DEALERS: FOR PRICES AND DISCOUNTS, WRITE ANY OF THE FOLLOWING DISTRIBUTORS: P. M. DREYFUSS CO., G. C. KOWFELDT & CO., 150 Chambers St., New York, N. Y. Minneapolis, Minn. NEWMAN-STERN CO., GLOBE COMMERCIAL CO., 1874 6th St., Cleveland, Ohio 618 Mission St., San Francisco, Calif. A. W. MARSHALL CO., R. E. T. PRINGLE CoO., 141 Jefferson Ave., Detroit, Mich. 95 King St., E., Toronto, Ont. Cc. H. WALLIS & CO., R. E. T. PRINGLE CoO., 1433 Syndicate Trust Bldg., St. Louis, Mo. 401 New Birks Bldg., Montreal, Que. SIGNAL ELECTRIC MFG. CO., BRIAN & POWERS, 33 S. Clinton St., Chicago, IIl. 304 Canal Bank Bldg., New Orleans, La. ALWAYS MENTION QST WHEN WRITING TO ADVERTISERS 79

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Price. $52.50 RADIO APPARATUS. NEW! 30,000 VOLTS—THAT’S THE SECRET. AND HERE IT IS, IN A NEW RADIO TRANSFORMER THAT SURE CHARGES THAT LITTLE CONDEN- . SER THAT YOU MUST USE WITH THAT OLD 200 METER SET OF YOURS. RESULTS WE SURE DO GET THEM WITH OUR CESCO 1 KW 30,000 VOLT TRANSFORMER. ASK ANY MAN THAT HAS HEARD 6BJ AND HE WILL TELL YOU “VERY QSA”. DISTRIBUTORS OF HIGH GRADE California Electric Supply Co. 643 Mission Street, San Francisco, Cal. THE Great Ameri SAY O.M.! Why wait two or three weeks for apparatus which you need quickly? Like everybody else, we do not have every instrument in the world in stock, but we do have a large supply, and we guarantee to make prompt shipments on the following goods:—DeForest, Grebe, American Radio & Research, Radisco, Modern, Benwood and Wireless Specialty. AMERICAN RADIO SALES & SERVICE COMPANY an Bldg., Mansfield, Ohio Radiophone Apparatus Let us send our Introductory prices on Vacuum Tubes, Modula- tion and C.W. Transformers, Transmitters, Chokes, ete. We can equip your station from the Motor-generator to the Aerial Circuits free to our patrons. Catalog and Monthly Bulletins 8c. DISTRIBUTORS ew = DeForest, Murdock, Moorhead, Amco, Amrad, Acme, Clapp-Eastham, Radisco, Thordarson, Burgess, and others. Liberal Trade Proposition for Responsible Dealers. KLAUS RADIO CO. Branch Office Eureka, Ill. Peoria, Ill. ALWAYS MENTION QST WHEN WRITING TO ADVERTISERS

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fe AREA ig fatal / Ge dee eceeseceke HK Ml Had 7 wees “hs MAR bbe nthe 4 4300 ANNOUNCING Our NEW SERIES “T” VARIABLE CONDENSER. A heavier model than our SERIES “S”’, but built along the same general lines. Plates are of s:” aluminum. We SPECIALIZE on ONLY THE BEST. SATISFACTION GUARANTEED. PRICES SERIES “T” SERIES “L” 20 2 plate i x No. 2300 23 plate .00075 70 «67 plate . . . No. 4300 43 plate .0013 . 130 13 plate . : , "170 17 plate . : No. 6300 63 plate .002 . 230 23 plate . ” e Indicating Dial fitted to either style . 310 31 plate . hsene a condenser for 75c extra. "630 ¢3 ee . m.f..... 7.50 NOTICE: Owing to shortage on cer- tain materials, we are unable to fill Include postage for one pound on orders for SERIES “S” Condenser at SERIES “T” condenser, and for two this time, but can ship NEW SERIES pounds on SERIES “L”. “T” and SERIES “L” from stock. The Wireless Shop 511 W. Washington St. A. J. Edgcomb. Los Angeles, Cal. Come to Headquarters for Wireless Books When you want the books that really teach—the kind that meet the requirements of engineers—amateurs—Radio schools & Government departments come to us. Practical Wireless Telegraphy By E. E. Bucher Anether New One. Cloth, 352 Pages, PRACTICAL AMATEUR 340 Illustrations. Cloth, " WIRELESS STATIONS Price $2.25 Fully Illustrated. An Experience Book Con- -= Price $2.25 taining the Best Sugges- How To Pass U. S. Govt. oo tions of Thirty-Three Ex- Wireless License Examinations How Te Conduct A Radio Club on Building, By E. E. Bucher By E. E. Bucher Paper, 96 Pages, 148 Pages, Fully Illustrated. Fully Illustrated. Price 75c. Price 75c. SAVE A year’s subscription to THE WIRELESS AGE may be A included with book order at only $1.50 additional. Regular 136 Pages. Peper. Price 50c price $2.00. 75c, Profusely trated. (Postage on subscriptions outside U. S. 50c extra.) WIRELESS PRESS, Inc., 328 Broadway, New York ALWAYS MENTION QST WHEN WRITING TO ADVERTISERS

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OMAN NAANAY NEN ANNY1L4) L111 E0000OUNNENOOUONNNL \ilt STANDARD RADIO EQUIPMENT AGENTS FOR— MURDOCK, BRANDES, BURGESS, GREBE, BENWOOD SPECIALTY, DE FOREST, FEDERAL TEL., AMERICAN RADIO, AUDIOTRON, CHICAGO RADIO LAB., DUBILIER, TRESCO AND OTHERS : NWOOD GAP-OPEN GREBE-DET.-RORH. U. OF I. SUPPLY STORE, Inc. 627-29-31 SOUTH WRIGHT STREET, CHAMPAIGN, ILLINOIS soi 01 VULVA TN A NEW INVENTION | | Youss& McCombs Rotary Spark Gap sica $16 COOTIE KEY, Double Action, Silver Contacts - Formica Base. Stands up to 2 K.W. Boos fnek . .*s “Lends Individuality to Your Sending !”” ickeled Finis OUR PARAGON RHEOSTAT HAS BECOME THE STANDARD FILAMENT RESISTANCE. 6 ohms—1'¥ amps. Fine adjustment on 4 or 6 volts. 2.” diameter. Smooth action! For back of panel or table mounting. $1.75 Postpaid The PARE 001 mf. Variable Condenser Immediate Shipment! (pat pendir the tong, Salt want for a rugged, HONEY COMB COIL ADAPTORS $1.50 per pair iced ec ; : tt “ice. "to bend and "short circuit. | | They make DeForest mountings unnecessary. They Cannot « order. Has very low minimum attach to the variable condenser. capacity mounted, only one small hole being nex the panel. Guarantee PARKIN Variable Condensers are sold to return within 5 days if not fully satis . No Postpaid 50. Unit May be mounted on any shaft. .$1.50 51. With | ter, ete. as shown in cut.. 2.00 52. With and 3” black dial We carry a complete line of all worth-while radio _— equipment, such as Acme, General Radio, Murdock, w | description of this new Chelsea, DeForest, Moorhead, etc. inv Ask for circular No. 17. SEE OUR AD. ON PAGE 97 PARKIN MFG. CO., San Rafael, Calif. itn lb mreay ap eng tag Mass. 82 ALWAYS MENTION QS T WHEN WRITING TO ADVERTISERS Write for discounts.

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The Amplifone—An Acoustic Amplifier With a good Vacuum Tube Amplifier and the AMPLIFONE head-receivers are no longer necessary. Even signals of very moderate strength can be read with this in- strument. The amplifying horn or cham- ber is contained in a handsome cabinet of formed metal, finished in dull black and nickel. The AMPLIFONE is 12 inches high and occupies a space of only 5 by 8 inches on your operating table. The instrument is connected in place of head- receivers and does not require a battery for its operation. Price $20.00 Shipping Weight—9 Ibs. The Doolittle Decremeter WAVE LENGTH DECREMENT (Patent Pending) A necessity if you want to obtain the highest transmitter efficiency and keep within the law. Entirely elimin- ates guesswork. No hotwire instru- ments to break or burn out. Designed for present and contemplated Ama- teur Wave Lengths. Price - - . $25.00 Shipping Weight—4 lbs. Send for Bulletins describing these Instru- ments and please give name of your de:ler. F. M. DOOLITTLE CO. 157 Valley Street, New Haven, Conn. ALWAYS MENTION QS T WHEN WRITING TO ADVERTISERS

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* introducing the RADIOLECTRIC SHOP “ of Cleveland, Ohio. Manufacturers of Local and Mail Order Service The First “73” Product. Radio Products. BEAUTIFULLY DESIGNED BLADE MOVES ONLY 2” SIMPLICITY ITSELF “73” SINGLE BLADE ANTENNA SWITCH urrent, rotary gap, or quenched gap fan, and power line, as well as antenna peration Marble base, nickelplated parts. . : : , ans we : oo od eee Wooden base, plain copper parts, tube ins. for base. . .$6.00 handle up to 2KW stations: Type B up to 1 KW. Both switches are heavy and by %” copper. Specially designed for quick action needed in A.R.R.L. work. tion, “B" battery is thrown off, and filament allowed to burn, thus making the ly for work when switch is thrown; no waiting for bulb to heat to proper READY FOR IMMEDIATE DELIVERY. RESPONSIBLE DEALERS WRITE. AGENTS FOR— APPARATUS ACME APPARATUS AMRAD Pacent Electric Co. Dubilier Condensers Baldwin Phones General Radio Co. Marconi Bulbs Murdock Apparatus Audiotrons DeForest tadio Engineering, Designing, Manufacturing and Installing Our M" and radio station open to all radio men. Come up and meet the bunch and get a AM \ 1 name and address for our mailing “mm agazine, the “FIFTH CITY OSCILLATOR” RADIO! EC TRIC SHOP, Dep’t Q, 919 Huron Road, Cleveland, Ohio list and we will send you a copy of our full of up-to-the-minute local news. The Largest Radio Supply Stock In The South IMMERCIAL AND AMATEUR WIRELESS APPARATUS OF ALL KINDS Holt Electric Utilities Co. Jacksonville, Fla. Southern Wireless Institute, Incorporated 423-425 Courtland Street Baltimore, Md. and Wireless Telegraphy. Day and Night classes. Board g for out of town students, rates $10 to $14 per week. aranteed. irry a full line of Amateur radio instruments and material. talog and Amateur bulletin furnished upon request. J. F. C. Buck, President. ALWAYS MENTION QST WHEN WRITING TO ADVERTISERS

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“SACO” PRODUCTS “Sacoclad” Coupling Transformers Patent Applied For. ’ . Two Stage Radio “Sacoclad” coupling transformers are Frequency Amplifier T Sta Audio a 7 Type RA-1, Price $65.00 Frequency Amplifier of the totally enclosed shielded shell type. Type A-2, Price $50.00 Primary and secondary windings are wound in pie sections, and assembled in alternate sections giving maximum possible coupling between primary and secondary windings Primary to secondary winding ratio is 1 to 5 giving a far greater voltage amplifi- cation than with existing marketed coupling transformers. The primary impedance is equal to the filament-plate impedance of the standard market three element vacuum tube. The flux leakage of the ‘“Sacoclad”’ Detector and Two Stage coupling transformer is practically zero, Audion Contrel Cabinet weg 2 y thus permitting the mounting of the trans- Type VDC-2, Price $50 Type DA-1, Price $75.00 formers in any position without fearing coupling between successive amplifying stages and at the same time avoiding howling and squealing. The “Sacoclad” coupling transformer the smallest transformer made, its physic | dimensions being 154” in diameter and 2” in height. It weighs 9 oz. Price $5.00 We build coupling transformers of any Radio Transmitter impedance. Prices on application. Radio Transmitter Continuous Wave Continuous Wave ARC Generator Type Tube Generator Type Hudson Radio Co., 182 Pulaski St., Brooklyn, N.Y. Sole Distributors of S. Cohen Products. ALWAYS MENTION QS T WHEN WRITING TO ADVERTISERS 85

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25. OOO Meters A Complete Short and Long Wave Regenera- tive Receiver, Detector and Two Step Amplifier Without a doubt the most efficient Receiver on the market at a price within the reach of all, consisting of Three Coil Geared Mounting, Primary Condenser Switch, Primary and Secondary Tuning Condensers, Grid Condenser, Stopping Condenser, Individual Filament Control, B Battery, Regulation for Detector Tube, Telephone Jacks for Reception on Detector, One or Two Step Ampli- fier. Complete Set of Sixteen Honeycomb Coils, 45 volt Variable B Battery, in fact a complete Re- ceiver that will outdistance them all on any wave length. th 16 Honeycomb Coils, 1 Detector and 2 Amplifier Tubes $215.00 th Coils less Tubes. .$198.00 Cabinet, less Coils and Tubes... .$165.00 st Complete Line of Radio Apparatus and Parts on the Pacific Coast Radio Call Books, each LEO J. MEYBERG CO. Successors to Haller Cunningham Electric Co. 428 MARKET STREET, SAN FRANCISCO, CAL. OH! Radio Amateurs We carry in stock a complete line A = BY of the following Manufacturers: J. H. Bunnell & Co. G 0 S H poe Apparatus Co. Wm. J. Murdock Co. You war w ACE Unicoil set. Any wave range f » 20,000 Meters, uses unmounted Tremaine Mfg Co Honeycor » Lateral coils, brings the sigs. . and the nout coil is only $40.00. DeForest Order co e length wanted, we have them. 10,000 +t Meter coil,—$3.35. 1,000 to 3,500 ——= Meters $ 100-1200 Meter coil $1.45. Amateur ; wave len $1.30 We have the best C-W ADDRESS ALL MAIL sets goin ATTENTION OF : MR. H. DUNBAR _ You may more, but you can’t Rememb« © --4 geary ea an aia The Precision Equipment Co., Inc. ite Light at Co. iring Engineers 728 Arch St., Phila., Pa. 2437 Gi Dept. D., Cincinnati, Ohio 86 ALWAYS MENTION QS T WHEN WRITING TO ADVERTISERS

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POWER TUBES LOANED te! | N ' ) | iN MR. F. S. McCULLOUGH, Vacuum Tube Expert, will give a Vacuum Tube Correspondence Course Covering a Period of 12 Months and will loan Two 100-Watt Power Tubes with Each Course PRICE OF COURSE, $45.00 F. S. McCULLOUGH 884 Grexton Road, Cleveland, Ohio ALWAYS MENTION QS T WHEN WRITING TO ADVERTISERS

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WONT ENAT TT PAARL LALA LUAUUUYAAEEOREOOOU OO AOAAANENATT 1, \NNOUNCEMENT Y E T 2 nedy Line of Receiving Equipment has made an enviable reputation for inship and performance wherever used. tly augmented engineering staff now includes electrical and mechanical wide experience in the design and operation of such well known High as BORDEAUX, ANNAPOLIS, SAYVILLE, ARLINGTON, PEARL \VITE, SAN DIEGO and EL CAYEY, which transmit across the Atlantic e of this enlarged organization is to supply even more effectively the | receiving requirements of the radio experimenter who is satisfied ort of the best. Kennedy equipment is being sold by leading dealers es; other territory is still open. COLIN B. KENNEDY COMPANY Rialto Building San Francisco ina intl OO EPENDABLE APPARATUS lr. Receptacle. 6 Step Grid Leak. (Pat. Applied For) Sealed in Bakelite. %, 1, 1%, 2,3,3% meg-ohm, Applied For) in single unit. = the 7’ 6 Step, $1.50; 3 Step, $1.00; Single grid leak, any te a a ae sone size, 50c. Grid mica condenser, separately or on inits may be dismantled and same base with grid leak, 50c. 10,000 to 100,000 re ohm units for resist up amplifiers, 85c. ney Sing Double, $2.00; Triple, $3.00 Mica teleph d » 75. RADIO INSTRUMENT CO., Washington, D. C. ATTENTION, YOU RADIO MEN department is ready to serve you—We are equipped to handle all y due to the fact that we maintain a force which is ready to give you vhich you are looking for. ve in Cuba your order will receive the same personal attention which it i: walked into our store and took your purchase out with you. That’s our r where you live. ipply you with practically every make of radio apparatus which is of grade. We have everything from a ground clamp to an antenna in- to ship to you. Just state your needs and we will care for them. tin 100 will be ready October Ist. You had better drop a card for your hat you will be sure to get one. OUR MOTTO IS “QUALITY FIRST, THEN SERVICE” M turers and Distributors of Radio Telephone & Telegraph Apparatus. THE NORTHERN RADIO LABORATORY 111 MAIN STREET, CLYDE, OHIO 88 ALWAYS MENTION QST WHEN WRITING TO ADVERTISERS

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INCREASE YOUR RANGE vas GET YOUR “SIGS” THRU! i Franklin Rotary Spark Gap A representative item from the Franklin Line of Radio Apparatus of Quality Priced Right! Not to be compared with the ordinary spark gap, which is nothing more than an assembly of parts. This gap is correct, both electrically and mechanically; designed for operation on 200 meters or less. Its many advantages are quite apparent to the wide awake amateur; proper quenching, short current travel, sharp low tone note, tested at 40,000 volts. For all sets using \% to 1 K.W. SPECIFICATIONS — MOTOR — Hamilton-Beach, the best small motor made; Universal, 110-120 volts, 60 cycle, OPERATING SPEED of gap is 4090 R.P.M., quick starting, ROTARY DISC—Turned from ,\ inch sheet Bakelite, lathe turned, satin finish, fitted with 12 heavy brass electrodes, and balanced. Diameter 6% inches. STATIONARY ELECTRODES mounted on Bakelite base, and are adjustable, as shown. Terminals are extended 2 inches from pillars and have heavy binding posts; base has satin grained finish to match disc. FRAME is a special iron casting, black japan finish, oven baked. FINISH—DMotor, stationary electrodes, binding posts, etc., are nickel plated and polished, giving a most refined appearance. All parts renew- able. Order yours to-day—the first trial will convince you. Shipping weight about 10 Ibs. Catalog +M-500—Price complete $40.00. THE FRANKLIN POLICY—YOUR SATISFACTION IS NOT DEBAT- ABLE—YOUR MONEY WILL BE PROMPTLY REFUNDED IF YOU ARE NOT ENTIRELY SATISFIED. CATALOG READY SOON—SEND US YOUR NAME. DEALERS—WE HAVE AN ATTRACTIVE PROPOSITION FOR YOU! FRANKLIN SALES CO. 1con. wens, cutcaco Manufacturers and Factory Representatives. ALWAYS MENTION QST WHEN WRITING TO ADVERTISERS

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Radio Telephones ! E herewith present to the discriminating radio W enthusiast, a superior radio telephone licensed under the Sterns patent. We believe we have produced an instrument that stands in a class by itself. Designed by a well known Radio Engineer, executed by skillful mechanics in a manner and of such materials as you would wish in your ideal set. Bakelite insulation throughout, all metal parts highly finished, Weston instruments, Bake- lite panel, and mounted in a piano-finished mahogany cabinet. Due to its liberal rating and compactness these sets will give reliable service far in excess of guarantees. Buzzer Modulated or Continuous Wave Telegraph 150 Miles. PRICE $375 Tele; ic Range 100 Miles Including Motor-Generator ; et is complete ready to operate except for 8 volt storage battery and three Class Marconi-Moorhead tubes. The tubes are mounted within the cabinet. verall 919" x 12%" x 6", making installation possible in cramped quarters, such as motor-boats, apartment houses, etc. The motor-generator is absolutely noise and can safely be kept in the operating room. Our sets have been delayed, but announcement will be made when they are available. e moved to larger and more commodious quarters. Note our new address. THE RADIOLAND CO., 209 Alsop Street, Jamaica, New York City LEARN RADIO A wonderfully interesting vocation giving oppor- tunity to travel, study foreign trade and busimess ad- vancement. Students in this school study under Expert In- structors, get Electrical Theory and Laboratory in one of the best Electrical Laboratories in America. Code by most modern methods. Practice on most modern 2 K.W. ship station. For special Bulletin of Information address, Portland, Ore. Oregon Institute of Technology ‘divi. ¢ A. P. MERCHANT CO. 9 Avery Street, Boston, Mass. You are invited to visit our store and inspect one of the largest stocks of high grade radio apparatus in Boston— Our Radio Department is in charge of an expert. | ALWAYS MENTION Q$T WHEN WRITING TO ADVERTISERS

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Knock ’em Dead... Get a Benwood Gap Silent in Operation... Every time you hear a clear musical note “busting” thru the QRM you can almost bet st’ o « Ih NT 7 Siciwied Gce Coon it’s a BENWOOD. “Makes a 1 K.W. outfit out of a 4 K.W. outfit”. You are going to have the best sooner or later so why not get it now. Make your call famous thruout the country. Notice how many pictures are shown of sets using the BENWOOD gap. “There’s a reason.” Listen to the notes and loudness of this gang and judge for yourself. 1AK, 1GZ, 2IR, 3BZ, 6AS, 8ER, 5ZA, 5YH, 5ZL, 9ZJ, 9ZV, 9LC, 9KV, 9KO, 9HW, 9CA, SET, 9LR, SDV, 9QJ, 9HN, 9GO, 9BG, 9SC, 9JA, 9CP. Absolutely guaranteed against electrical breakdown. 3akelite insulation. HERE’S A REAL DISC. Give the old spark a chance and it will do the rest. Has WIDE sparking points. It is true to the hundredth part of an inch. Is specially designed for 1K.W. Drilled to fit any sized motor shaft. 4 to 14 points. The sparking points are tapered, thus giving the much desired “quick break” Specify size motor shaft when ordering. All standard apparatus carried in stock. Order by radio. We’re on the job every night. THE BENWOOD COMPANY, INC. SLC Cor. 13th & Olive Streets ST. LOUIS, MO. ALWAYS MENTION QST WHEN WRITING TO ADVERTISERS

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“C.W.” Transmitters by all progressive Amateurs during the coming season. We carry a material and parts required in building a C.W. or Radio Telephone pleased to forward Bulletin No. 5 which gives prices and full large Blue Print and instruction sheet of an approved C.W. circuit Any further technical questions will be answered free of charge. W. Equipment we carry a complete line of both Transmitting and tus and every order will receive “Personal Attention” and IMMEDI- NT. Complete DeForest line—order from your catalog or write for our list each month—it will contain the latest Radio Developments. Genuine 2 Filament AudioTrons feCo AudioTron Adapters Acme Unit Audion Detectors \cme Unit Audion Amplifiers General Radio 4 Step Inductors Chelsea Variables, O12 BLP... 2. cccccccccccces Chelsea Panel Condensers, .0012 M.F..............+.: helsea Variable Grid Leak Weston Voltmeters, Scale 0-500 Volts \mrad Wavemeters International Oscillation Trans Murdock Moulded Condenser, section Cootie” Transmitting Keys onsolidated Call Book (with map) Signal Rotary Spark Gap, 1 K.W HICAGO RADIO APPARATUS CO. Michigan Avenue, Chicago, Illinois

STOP ALL LEAKS and gain in efficiency. You insulate your aerial carefully, why let energy leak away through the lightning switch? Any switch on a smooth base will leak when carrying a current of more than a few hundred volts, even when dry.

rIFIER TUBE sed. generally in pairs, for alternating current for ireuits of Radio Telephone radio power tubes. They make

Install this “Special Radio” switch with jaws and blade mounted on corrugated Generator Unnecessary electrose insulators that will stand tify up to 500 volts and 40,000 volts, and you will be surprised each, normally, sufficient and pleased with the results. Switch carries 100 amperes. Shipping weight ce, $7.00 each. 8 Ibs. livery from stock. PRICE $8.75, POSTAGE EXTRA. istrated circular No. 15. LESTER I. JENKINS ~<~ EQUIPMENT CO., Inc. 923 Purchase St., New Bedford, Mass.

Catalog of other apparatus and wich St., New York, N. Y. pocket code card for a 2c stamp.

ALWAYS MENTION QS T WHEN WRITING TO ADVERTISERS

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aa The RADIO SHOP Short Wave Regenerative Receiver combined with the latest addition to an already well established line. The “RADIO SHOP” Detector and Two Step Amplifier. A unit possessing features not found in other sets available on the market today. Scientifically designed for amateur wave-lengths. Magnetically screened throughout for ccemp/ete elimination of “feed-back” howling. Transformers of correct proportions for present day tubes. Non-heating rheostats. Tube sockets which take either standard V-Ts or Navy type valves. Hinged cabinet top for easy access to interior for removal of valves. Mica fixed condenser in detector circuit of correct capacity for regenerative circuits. Separate plate battery control for detector and amplifier valves Extreme simplicity of connect'ons. Connection strips furnished for connection to short wave receiver. Furnished without valves or batteries. , : $75.00 The “RADIO SHOP” Short Wave Regenerative Receiver. Now licensed under Armstrong U. S. patent No. 1,113,149. Described in detail in previous issues of “QST”. New Price........ .. .$45.00 Both sets sold with the distinct understanding that your money will be immediately refunded if you are not satisfied. We will shortly have interesting literature on the above and other “RADIO SHOP” products. A stamp will put your name on our mailing list. THE RADIO SHOP Bank of Italy Bldg., Devt. Q, San Jose, Calif. FOR EASIER AND BETTER TUNING By using a set of the new GENERAL RADIO 4 STEP INDUCTORS you can receive every wavelength from 140 to 22.000 meters with a variable condenser of .001 M.F. You do not need so many coils, or to change them so often. You do not need an auxiliary mounting. You are not inconvenienced by the connections pulling out or breaking off Each coil is mounted complete in a polished oak box, with engraved bakelite panel, switch and binding posts. PRICE $6.00 EACH Full data in Bulletin 302. GENERAL RADIO CO. 4 STEP INDUCTOR Windsor Street Type 226 CAMBRIDGE 339, MASSACHUSETTS We are prepared to supply the amateurs of the Capitol district with a full line of high grade in- struments and parts and also make to order any se and Wireless and RAILWAY ACCOUNTING special apparatus they may require. a, yt t y and quick], Big salaries now paid Gregt opportunities for advancement. Oldest and largest THE SHOTTON RADIO MFG. COMPANY school; established 46 vears. Endorsed by Telegraph, Rail- way. Be 2 and Government officials. Expenses law 8 Market St.. Albany _ w _..opportunities to earn large portion. Catalog free . ® a * —Open Evenings— DODCE’S INSTITUTE @ Street, Valparaiso, ind, ALWAYS MENTION QS T WHEN WRITING TO ADVERTISERS 93

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The o the demand for a ‘RE LIABLE AND PROMPT SERVICE tube repair work announce their entry into this field. odern equipment and skilled workmanship, satisfaction is assured, and re made possible within 10 days of the receipt of your order. Eastern VACUUM TUBE laboratories AUDIOTRONS, ELECTRON > ees 3 5 MARCONI VT’S, MOORHEAD VT’S $ 0 Western Electric VT’s and power tubes quoted on application. CASH MUST ACCOMPANY ALL ORDERS Eastern Vacuum Tube Laboratories shington Street, Boston 12, Mass. SPE‘ — Nicl Screw 42 MAID 94 Quality Satisfaction ng the WHITALL CO., of WESTERLY, for the Latest Radio All the Leading le Island Jobber for ECTRON RELAY. \L FOR THIS MONTH Contact Points and 2 cents each. r Our Next Month’s Whitall Electric Company ST., WESTERLY, R. I. | Letters 1IAP id = NEW ORLEANS RADIO APPARATUS AND SUPPLIES ROSE RADIO SUPPLY 604 GRAVIER STREET NEW ORLEANS, LA. Send 10c for Latest Catalogue Pure Copper AERIAL WIRE 14 gauge—hard drawn 2 FEET FOR 1 CENT 12 gauge—S0c per 100 foot roll. Add cost of postage. No C.O.D. orders. Send 15c¢ for our big illustrated catalogue show- ing scores of other bargains in radio apparatus. This amount may be deducted from first order of $1.00 or over. High printing costs make free distribution impossible. ELECTRICAL SPECIALTY COMPANY Dept. T, 48-50 South Front St., Columbus, Ohie Dept. T, 20 North 9th St. Philadelphia, Pa. ALWAYS MENTION QST WHEN WRITING TO ADVERTISERS z

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A NEW RADIO REASON | This unit con- There is no tains three magnetic leak- : age in coup- Turney Spider- ling. Thecoils web inductance being flat, the| coils. Two entire magnetic area of the coil| ™®v able and is available. one stationary. There are six The wire runs binding posts parallel for a | permitting most STATEMENT: I More inductance Less distributed capacity greater distance | any type of cir- — y -~ gf cuit to be used. quently than)| The doors as any coil known.| shown in cut are capable of © fi d- There being no teed ae . a interior magne- | / _ ror tic field or air | stay where core, high fre-| they are placed. quency resist- With ¢t ance is reduced _ to a minimum. | densers, .0005, and .001 mf. it will respond The coils are| t?¥#ve lengths, so thin that; !75 to 400 three of them | meters and eccupy less than one- Lower high frequency resistance en 1 oa >< Occupies less space

give results

quarter inch. such as you have not had before. . The winding. ole angle at crossi = - HOLMES Formica core

SPECIAL PRICES Unmounted Grid Condensers @... . $0.30

Brass Contact Points @ per doz..... .20 The Corwin Indicating Dials @..... 1.25 Practice Key with Buzzer, ae A PPT ETP 1.40 “B” Batteries, worth $1.35, @..... 1.00 WU «cs cevidhsen es oa 60.6 4.50 American Electric & Wireless Supply Co. Mail Order Dept., 335 Broadway, New York City Telephone, Franklin 1900.

Tr FREE

Turney Spider Web Inductance EMBODIED IN A SMALL UNIT

Eugene T. Turney Laboratories

LL TT S f ASHEVILLE NY ( ctssriee* PRODUCTION THE TURNEY SPIDER-WEB UNIT Formica wound thruout. Patent Pending DIMENSIONS 414 x5x 1%” Further information on request Radio Hill NEW YORK

Our Improved Honeycomb Coil Adaptors can be used in many New ways—as in back-of-panel coupling mountings; attachment plugs for Radisco coils, ete., because it has Adjustable arms—per- mitting it to fit any pair of binding posts, coupling rods, etc. 75¢ postpaid.

Our Bulletins sent t for 4c—Include— RADIOPHONE & “CW” ACCESSORIES Type J 0-3 ammeter, 3” dia. flush type... . .$6. Non-melting bakelite VT socket, for ‘phone sets 1. Electrodyne rectifier VT’s (60-70 M.A.). 7. Unmounted 50 watt rectifier transformer. ss 1% henry choke coil, 150 M.A. semi-mounted. 4. And many other new _and _unusual items. —-BRBEE Place, your order, or; Buzzer Radiophone $135 Somerville Radio Laboratory 102 Heath Street, Somerville, 45, Mass.

RADISCO AGENCY © tan eet eho

A piece of extra sensitive silicon upon —mmees FOR THIS DISTRICT receipt of two or more names and ’ Semen ee Oe eee me © jal :- VT and Tron Recei Set on Formi ee ee a irr Fa load 16 wih & plate Verebe oud Univeral Col 313° J. J. YOUNG = Tt a= asa = x Radio Apparatus and Supplies ANUFACTURERS AND DISTRIBUTOR 717 W. Gray St., Elmira, N. Y. * HI- GRADE WIRELESS INSTRUMENT cO. *

ALWAYS MENTION QS T WHEN WRITING TO ADVERTISERS 95

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mit an frie LIN cor Pal Rep W EI $25,000 Catalog Free ing like it ever published. It positively will do your heart east your eyes on this wonderful book. It is a real Experi- book, full of photographs, bargains and surprises. The finest IRELESS INSTRUMENTS & SUPPLIES are shown, together il line of SCIENTIFIC INSTRUMENTS, COMPLETE LABOR- 5, CHEMICALS, SUPPLIES & GLASSWARE. It is a veritable the Wireless, Chemical and General Experimenter to delve in over things he has long desired but could not find. In short, t’s impossible to describe this wonderful book. The edition is ED.. Send 12 cents (refunded on order of $1.50) for YOUR )-DAY, to the ers Electrical Equipment Co., Palmers, Minn. tives for: Amrad, Acme, Murdock, "Doron Bros., Burgess, Moorhead. — —E - ———— NOW HAVE WE HAVE ’EM 100, ready for distri- ily illustrates and de- The C & S Navy Type Dials—90c Post- ilar Blank Cabinets, ad- paid anywhere. Can make immediate ssues of QST, as well shipments from stock. er specialties ' Send for circulars concerning Chelsea . Radio Co.;Park'n Mfg. Co.; DeForest enclosing stamp. Apparatus; Mcorhead Vacuum Tubes; ’ ‘ P Baldwin Phones; Brandes Headsets; and » enn others. PR Radio A C Ask for a copy of Radio Examination “ {2 adio Apparatus Co. Questions and Answers—lIts Free! ¢ 0 1157 Green St., A. F. KRAUSE & COMPANY | Dept. C, Reading, Pa. 689 McDougall Ave., Detroit, Mich. COMPLETE RECEIVING SYSTEM-$25 Aerial System, Cabinet Set, Buzzer Test and Phones EASTERN RADIO LABORATORY New Jersey Representatives Wanted. ALL. TYPE —— $$ \RIOMETERS VACUUM-TUBES REPAIRED ‘em and weep” Marconi—Moorhead— Audiotrons perfect stat F di . Four Dollars Each, Postage Paid es £ ae Standard Grid Leaks, $1.25; Bases, 60c; and yours for 25c. Sockets, $1.00. gPrge aw THE DALTON LABORATORY K S 73 Ve i. ae” Dalton and Belvidere Sts., Boston 17, Mass. ALWAYS MENTION QST WHEN WRITING TO ADVERTISERS

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Amplifiers Control Boxes Vacuum Tubes Telephones Real Radio A pparatus Condensers Variometers teceivers Complete sets Standard and Special To the amateur and experimenter desiring Standard apparatus, we offer our complete line such as we supply to the U. S. Navy and Army, high grade commercial and foreign governmental institutions. Our Radio and Audio Frequency-Multi-Stage amplifiers represent the highest development in this line. WIRELESS IMPROVEMENT COMPANY Radio Engineers—Manufacturers and Distributers 47 West Street, **Contractors to the U. S. Navy and War Depts.’ New York Radio Amateurs WE REPRESENT Amrad DeForest Firth Acme Apparatus Radio-Craft Chicago Radio Laboratory Burgess Battery Co. Perfection Apparatus Murdock Clapp-Eastham Connecticut Tel. & Elec. Co. Brandes Precision Apparatus Wireless Equipment Co. Wireless Mfg. Co Benwood Apparatus Amateur Wireless Equip. Co. Richter & Schottler Arrambee Jacks Stromberg-Carlson Esbro Chelsea Radio Co. Pacent Electric Co. A. H. Grebe & Co. Continental Radio & Elec. Corp. Radio-Shop Federal Teil. & Tel. Co. International Radio Tel. Co. Moorhead Bulbs Magnavox Dubilier Marconi Write for literature. HARRISON & DUDLEY 738 W. Church St., Elmira, N. Y. Dealers write for attractive trade proposition. AERIAL WIRE lc. foor 7 strands No. 22 solid copper—tin plated to pre- vent oxidation. Maximum radiation and strength. Include postage on 15 Ibs. per 100 ft. GROUND WIRE 8c. Foor . $7.00 Per 100 Feet No. 4 solid copper—rubber covered—triple braid include postage on 20 Ibs. per 100 ft 100 amp, 600 volt lightning switches, $4. “‘October’s Special Value!’’ DeForest CV500 Variable Condenser Max. capacity, .0005 mfd.; min. cap., lowest possible value, without small knob and pointer. . $6.05 Large 37%," Corwin knob and dial, value... ..$1.70 Special sale price, z e $6 25 >! List value, $7.75 44 VOLT VARIABLE “B” BATTERY $3.60 Include postage on 4 lbs. Complete in handy wooden case and adjustable phosphor bronze “jiffy’’ connectors. Better than block batteries—if one 4.4 V. unit weakens pre- maturely, it can be removed and replaced—thereby not impairing total voltage, which makes this the best battery value to be had at any price. Fresh 4.4 V. renewal units always in stock, 40c each. Our original AudioTron adaptor permits use of you ‘tron in a VT socket, $1.75 postpaid. STANDARD VT SOCKET, $1.00, Why Pay More? SEE OUR AD. ON PAGE 82 RADIO EQUIPMENT CO. “* Specialists in Prompt Service and Maximum V alue"’ 620 WASHINGTON ST., BOSTON, 11, MASS. ALWAYS MENTION QS T WHEN WRITING TO ADVERTISERS 97

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CLASSIFIED ADVERTISEMENTS BARCAIN:. of ‘Scnoo™bes itn 'W. Cecll ‘Bridges Five cents and addr by the 10 BARGAIN 5 copies Construct price $1.7 TELEGRA way Ac Big salar school earn are St., Valpa ALI AM accordan book June and get you Mass TRADE Homsher FOR SA ser (ua M. Selby FOR SAI receiving $10.00 meter, an transform Boston k 5047 Wa WANTE ceiver A Jersey ‘ AMATEt Blade A this issue vited to meet the Your “Fifth « Radiol« FOR SA weight 4 K.W $1 Ave., New FOR SAI formers Vv. & D FOR SAI One Sever Earl R. W SELL OR Earl Aust ATTENTI equipped Refer to the ilust Relay wus Oscillator mitting quantity AudioTron need no fidence an profit on the follow Relay, list Amplifier The Moorh price oni list price of the al condition ment of charge St.. Dept FOR SA! case two attachmen or Parago win or W Grebe syn you? B 98 $6: our price only $5.50. The A-P Radice Laboratories, 901 W. Ist R. T. Ss. e, Kansas. zi Instruments oe material me backed by a XCHANGE: —" B- “flat cornet in ge > hed —_ pieces——music clip an -sharp new—never been used—want $70 STYLE = 3 ae Cee. $0.70 be regenerative receiver with Bald- nd stamp for circular ctric fones, or will add $30 for RADIO TESTING STATION gap—make me an offer—what have 25 Sturges St. Binghamton, N. Y. ng, SO Whiteford Ave., Atlanta, Ga. —_ i per ee in advance. Name Navy Radic, Duluth, Mina. counted. must be received nth for F. . ‘month's issue. WILL _ EXCHANGE ‘fime new Boehm system clarinet for good wireless transmitting or receivin %, instru- ments, (or both) or will sell for $75.00. rite me KS: QST Book Dept. has | on , hand what you have. All correspondence answered. C. 0. \. P. Morgan's “Wireless Telegraph Williams, 843 Knowles St., Royal Oak, Mich. steurs”. A valuable book. Regular eh RS e quickly, $1.00, postpaid. NEW: 2 Murdocks 23 variables $2.75 — $4.50 - —— vario-coupler $3.75. Donal, Elkins Park, P th Morse and Wireless) and Rail- t quickly. Tremendous demand. FOR SALE: New Klitzen Variable Oil se ypportunities. Oldest and largest Condenser No. 112, $20 prepaid. W. B. Short, 75 years. All expenses low—can West North Ave., Atlanta, Ga. og free. Dodge's Institute, R na FOR SALE: Omnigraph, Transmitting and Receiving PPARATUS bought or made in Set. Also other parts. Box 3051, You Street Post Radio Buyers and Builders Hand- Office, Washington, D. C. lls very profitably. Study my BARGAINS: Tube . . . . pene! “datecter, $2.50; lightning i. sey "Rd = switch, $1.50; Murdock variable condenser, $1.50; , ” ° Telegraph key, $1.00; Tel-Radio detector, $2.00. Al! —EEE perfect condition. J. G. Dilworth, 518 Rosyin Place, Radio Operators Helmet. Frank Pittsburgh, Pa. sside, Penna. LT FOR SALE: 8 complete eots Western Electric phones tions Murdock Moulded Conden- selling everywhere for $16.00 at $9.50. 8 Wireless endition $10.00. Address C. Improvement Company field type receivers § type St.. Muskogee, Okla. Z . CN113A worth $75.00 for $48.00. All new; cash. 1 retary gap end Clesp-Racthem — prepaid. E. A. Dix, Central Ave., Lakewood, absolutely ge $25.00 and vee C— oe . ‘ a. postpaid. Also itzen ~wave- SWITCHES and Switch Points, best on the market. sductance; one K.W. Thordarson Send stamp for circular. Liberty Radio Supply Co., motor; oscillation transformer; 6808 Aberdeer St., Chic til. is No. 30 magnet wire. Crowdus, ~ porno . —— e., St. Louis, Mo. FOR SALE: 40-volt Marcuson “B” storage battery, CR-3 Special Regenerative re- slightly used, $8.50. Like new. Send stamp for list. M. Liedeker, 61 Cornelison Ave., Elmer G. Baier, 253 Ninth St., Brooklya, | N. Y. = GENUINE “JUPITER” aerial wire. Seven strands you seen the new “73” Single number 22 solid copper. 100% conductivity. 1c ’ See our add on page (84) per foot, $12.00 thousand. No C.O.D’s. 15 pounds in Cleveland and vicinity in- per 1000 feet. nd pootage. a A. Bates, 8 Moen sur famous “Static Reom” and Street, Worcester, Massachusetts. radio men, and use our radio set. ————_. ess will bring you a copy of the HELP WANTED, a Prominent concern manu- the new local radio magazine. facturing commercial radio equipment requires the 19 Huron Rd. Cleveland, Ohio. services of cagrescive, inteilis intelligent sales engineer. A . technical know e of undamped wave transmitters Rtg Ath gt wg essential. Only with selling experience con- = 6 decheen O06 Geeeneteh sidered. Salary and commission, also wide terri e ° for sales promotion to ht party. State fullest — ae particulars. Box 57, % QST. K.W. Thordarson wireless trans- W. Thordarson transformer. The Franklin, _Ohio. mnigraph Number Two Jur, SOMMORT WAVE COUPLER Clapp-Eastham Condenser (New). a, S. D. —170-625 Meters— ended mile conding ot Wee | Weg, ith 20/38 ite osha Tatine, Renter Virginia. Used by VU. S. Government in SCR-54 Rec@iver. EURS!! ba oe Pango nne > PRICE $4.50 UNMOUNTED Shaw standar our prong se. tisement in this magazine giving GOUSE & LORENSON descriptions of the A-P Electron U , Oe tector and the A-P Amplifier- HUDSON, nlso carry the Moorhead trans- . sa a ae I »-date radiophones and a limited ine double filament double life s, amplifiers, oscillators, which In order to gain your con- we are sacrificing a considerable s and are offering them to you at sctive prices. The A-P Electron st price $7; our price only $6.50. LACEY +, oom mitting tube, list price $7.50; our tine double filament AudioTrons, rice only $5.50. Each and every is guaranteed to arrive in good a eet rove fully satisfactory. Replace- tory tubes will be made free of ALWAYS MENTION QS T WHEN WRITING TO ADVERTISERS wit MTT LL LLL LL want PONVOTUDLODU ELTON PUDADADAALONUELIUAAAE TENNENT TOUAAAALAAUUIAEL SHH LLL

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SANNNNTOTOOANNGNANOQOUONSSNOQNUQQOUOENSOGNSUOUNLUUNSEAAUAELCESORTENTALLOUUUUOOEASOGLOUHGOORGOTEA AAD Indicating QUALITY The Corwin Indicating Dial, by its ean superior performance of accurate inductance is recognized by radio men as a popular and needy addition to any set. It has been further improved and now comes in two sizes, three and three and seven-eighth inches in diameter. This larger dial (3% ”) fills the general de- mand for an indicator to fit the standard one-quarter inch shaft: quality and work- manship better than ever 3” dial only, 75c.; with knob, $1.30. 3%” dial only, $1.00; with knob, $1.70. Sent postpaid anywhere. We are distributors of the better class PNteONNAtON TDNUOSUITONL EU EYA OY TEOARAA ENOL OAA OANA EAA EAA ANNAN AANA AA enNNNNNN NNN NMNTU MONO ENL ANU ANUCQOUENOEGONOLONUAAUUOULENUUGUUOGUENUEGUONURNUENOHeTOONENOOONOUNAEONOONO NOU eNOuNNONNUANOaNueNDeaNuennenvennnnnonNOn IVYVQYVLALOO000QSUQ0000 0 000GNN04OOOUNOAUEOOOOOOUOUOONSOANOOOOOUORONDNGONONLOOUUOOUUAONNNNOSGMOUUONOGHNEAU MTU VOOROAGSOOOOOUOOOOEN OOOO GASAAAONGLOU OO AADAGOUUOUOOUOGHAASIOONUOUUONEGAGGOOOOOOONNNNAOOOLOGOOONOEOOONOOOOODONOONNNNOOULOONNO4N44UUU0U00LL00004444000000NRTHOUOGUUUEEONNNUOUUUUUUUUANNNNNNNNNUQNUUqNNNNHANUN) f radio apparatus and offer a superior service on products manufactured by A. = R ( Acme Radisc« Murdock, Radio : Craft Clapp-Eastham, Moorhead, ete = Ten ’ . stale to you I b al dia tandard l ADI i A. H. CORWIN & CO. Dept. D.4, 4 West Park St. NEWARK, N. J. UAVUAU ATEN ENON AUT AULT TOUTE ALAA SUMMA UU ALWAYS MENTION QST WHEN WRITING TO ADVERTISERS Immediate Delivery ON Condensers Oscillation Transformers Spark Gap- Rotors Place your order now for any of the above pieces of apparatus that you may need to complete your long distance transmitting station. Ve K.V.A. What is your best transmitting record on our type R % K.V.A. transformer? Send your records to this office. The best record will be published. THORDARSON Electric Manufacturing Co. 501 S. Jefferson St., Chicago 99

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Hook ’er to yer bulb A WONDERFUL TEST. CAN YOU BEAT IT? During the outdoor meet of the convention of the A.R.R.L. at Chicago, Sept 3, one of our 20000 meter tuners was set on the sand in front of 9ZN radio station, and the aerial was nothing but a piece of bell M eet long lying on the sand. The ground was tied to the ground lead of 9ZN. 21 f phones permitted everyone willing to read all the Arc Stations r that time. Good readable signals; and the time was from 3 te A further test was made in Room 760, Edgewater Beach H hanging the 50 feet of wire out of the window and the ground W to a radiator. European Stations were copied all night. All th ng amateurs of the middle west were at the meeting. The derful tuner in the world for only $10.00 during October only, as a] introductory price. Add parcel post. .bove tuner only $6.00, tapped and marked. Add Parcel Post. N A A—ARLINGTON TUNER—5000 M. T) er is same size as above tuner only it has a tickler coil and uses th nt audion hookup with tickler in series with phones. It is the 01 «x tuner that gets NAA on a small aerial without any variable m oupling. This tuner also gets the arc signals at 5000 meters an rds easily wireless phone talk from 600 to 5000 meters. Priced at $10.00 plus parcel post. KNOCKED DOWN OR ASSEMBLED CONDENSERS Vv nd do you want? Made for panel mounting al omplete with scale, pointer and knob. Used al er the world. No C.O.D. orders, add Parcel pe Buy from your local dealer or send us his name if in’t supply you. Formica tops and bases. M plates are now held by nuts and not clamped v her as formerly. 82 Plate Bae ete ade «scks $1.80 11 Plate assembled....... $2.75 Bi Plate Gee cede nc ces 2.25 21 Plate assembled....... 3.25 41 Plate Tidths cas ch becccs 3.20 41 Plate assembled....... 4.25 THE UNIVERSAL CONDENSER The only fool proof, complete assembled condenser in the world that will fit any cabinet, and take the place of any and all the condensers that you may be using. IT HAS A CONTINUOUSLY VARIABLE CAPACITY FROM .00025 MF TO .001 MF. Studs are so mounted as to prevent any leakage and to fit any holes you may have already drilled in your panels. Size 3x3x1” and shipping weight one pound. Priced at $2.50 and add Parcel Post. SOLD BY TRESCO, Davenport, lowa OR YOUR DEALER Be t and send Sc for our Catalog. Foreign orders solicited. Canadian Ama rs buy from Canadian Dealers. All products licensed under Marconi and Arn »n@ Patents. ALWAYS MENTION QS T WHEN WRITING ‘TO ‘ADVERTISERS

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‘) RADIO® 2 The almost complete absence of “effective resistance’ in the Connecticut Variable Condenser enables you to receive a _ signal often ten times the strength of that picked up with a rotary condenser. Combined with the finer adjustments given by this Condenser, this stronger signal capacity remarkably increases the efficiency of any set—which means an increased range Compact, stable, simple, operating smoothly throughout a scale of 360 degrees (twice the scale of the rotary condenser) the Connecticut Variable Condenser is one you should know all about. We have a brief booklet which tells the whole story. Your name on a postal brings it Mention your Dealer’s Name aoe

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ai i HIN LC MaRydgit a AN. q | || J Wi} Remember that the Amrad Quenched Gap and Amrad Adjustable Resistance in combination make possible a clear 240 s.p.s. or 120 cycle note well adapted to long distance relay work. Remember that genuine quenching is only ob- tained in two ways. First, by operating at terrific speed a rotary gap of special design. Second, by discharging the condenser—as in the Amrad Quenched Gap—thru a series of air tight chambers, each one small enough to insure rapid ionization and de-ionization of the vapor therein. sfance ” primary power ofe. but discharges FIG.3 a . Nin, _ Quenched Gap quenches | ee yyy. lose coupling and conse- more energy in a single ll any other type Gap rators. FIG.4 Quenched gap with primary resistance adjusted for uniform dowble frequency note Quenched Gap with 60 condenser discharges of induce antenna oscilla- tude far greater than is Quenched gap with addi tiona! resistence fo give clear, r more sparks per cycle rythorcal 60 cycle note. Greatest distances covered with this adjustment condenser. Send for Bulletin Q which fully explains the above graphs and com- the three sizes of Amrad Quenched Gap. For prices refer to our ed in this magazine. If you already have an Amrad Gap you can nsmitting range by following detailed directions in new Bulletin Q-1 P.S. Our claims are based strictly on facts. b to Address all Communications to New York Office, tw i A Beg 5 » °

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