Your Radio Problems Solved for 30 Cents in Stamps

F YOU are constructing a receiving set, a battery charger, a loading eoil, a con­ I denser, or a transformer and you need help in the way of clear diagrams and full detailed descriptions of that very thing you may have it by return mail. We have laid aside a limited number of back numbers of Radio Age for you. Be­ low we are listing the hook-ups and circuit diagrams to be found in these magazines. Select the ones you want, enclose 30 cents in stamps for each one desired. We advise immediate attention to this as the stock of back numbers is diminish­ ing rapidly. May, 1922 June, 1923 -:-How to make a limple erYltaJe.t for 18. -How to build the new Kaufman receIT8f. -What about your antenna? June, 1922 July, 1923 -How to make a Receiving Traneformer. -Aerials under ground and under water. -The Grimes inverse duplex system. -Electrio light wires as auxiliary to radio. -How to read and follow symbola. -Proper antenna for tunina:. September, 1922 August, 1923 -How to construct the Reinarh Reoeiver. -Construction of the Cockaday four-circuit tuner. -Federal Act regulating radio. -An efficient two-stage amplifier. -A simple buzzer transmitting set. October, 1922 -How to make a Tube Unit for $23 to $37. September, 1923 -How to make an Audio Frequency Amplifying Trans- -How to load your Bet to re~eive new wave lengthl. former. -Simple Radio Frequency Receiver. November, 1922 October, 1923 - Photo-electric Detector Tubes. -The Four-Tube Neutrod7ll•• -Design of a portable short-wave radio wa'Yemet ... -Your Firat Tube 8et.

December, 1922 November, 1923 -Supply exhausted. -The 8uper-Heteredy.... -A. Three-Circuit TlIaer. -How to Learn Code. January, 1923 -How to make a sharp-tuning Crystal Detector. December, 1923 -Fixed condenserl in home-made receiving set.. -Building the Haynes Receiver. - Description of loading coil for limple lets. -Combined Amplifier and Loud Speaker. -A Iilebctive Crystal Receiver. April,1923 January, 1924 -The Koppruch .ireult. -Bow to make a one-tube loop a.riaJI". -Tuning Out Interference-Wave Traps-Elimina­ -A two-circuit Crystal Bet. tors--Fil ters. The article which was favored with the grateful Interest of the May, 1923 radio public after its announcement by Station WJAZ. -A Junior Super-Heterodyne. -How to make the Erla linde-tube reflex receiver. -Push-Pull Amplifier. - Bow to make a portable Reinarts let for summer ule. -Rosenbloom Circuit. RADIO AGE, Inc. 500-510 North Dearborn Street. - CHICAGO, ILL.

I RADIO AGE-"THE MAGAZINE OF THE HOUR"

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Inside the Arctic Circle, nine degrees from the North Pole, a little 89-foot schooner is frozen fast in the ice of Smith Sound. Aboard Model 4R-The new Zenith 4R "Long-Distance" this schooner a group of brave men are enduring, Receiver-Amplifier comprises a complete three­ as best they can, the desperate cold of the Arctic­ circuit regenerative receiver of the feed-ba ck type. It employs the Zenith regenerative circuit in cold that often drops to 60 degrees below zero. combination with an audion detector and three­ Human atoms in a boundless field of ice! stage audio-freque ncy amplifier, all in one cabinet. Cold is hard to endure, but far more terrible is the Because of the unique Zenith "selector," unusual selectivity is accomplished without complication of Arctic solitude-unbelievably oppressive. Radio, at adjustment. length, has broken this spell forever! The Zenith 4R ma7 be connected dire ctly to any loud-speaker without the use of other amplification Concerts from Honolulu! for full phonograph volume, and reception may be ( ( satisfactorily accomplished over dis tances $85 Daily, by means of powerful sending and receiv­ , of more than 2,000 miles ing apparatus, the crew of the "Bowdoin" are in L, communication with relatives and friends in the \ far-off States. Daily they listen to concerts as far away as Chicago, Dallas, and Honolulu! c~ '~ When the sanity, the very lives of one's shipmates may depend upon contact with the outside world, none but the best is good enough. r '/ 1/ I Dr. MacMillan's Choice-the Zenith l! I J Out of all the radio sets on the matket, Dr. ( Model 3R-The new Zenith 3R "Long-Distance" MacMillan selected the Zenith exc1usive1y-because Receiver-Amplifier combines a specially d esigned .of its flawless construction, its unusual selectivity, distortionless three-stage amplifier with the super- its dependability and its tremendous reach. efficient Zenith three-circuit regenerative tuner. I Fine v ernier adjustments- in connection with the Already his operator, on board the "Bowdoin" in I A unique Zenith a p eriodic or n on-resonant " selector" Northern Greenland, has tuned in several hundred . ! primary circuit- m ak e possible extreme selectivity. stations. You along the Atlantic who brag a little PI 2,000 to 3,000 Miles with Any Loud-Speaker when you tune in Catalina Island-what would you (I' The new Z enith 3R h as broken all records, even . Ii h A . C' l? those set by its famous predecessors of the Z enith line. say if you tuned In Hawaii rom t e rellc lrc e. I Satisfactory reception over distances of 2,000 to 3,000 The set that Dr. MacMillan has is a standard 1 miles, .and o ver, is readily accomplish ed in full Zenith receiving set. And you can do all that 1, volume, using any ordinary loud-speaker. N o special skill is required. I The Zenith is the only set built which is capable of new models shown at the right. Their moderate ' being used with all present-day tubes as well as price brings them easily within . ' , with any tubes that may be brought out in the future. your reach. Write today for '~% The Model 3R is compact, gra ceful in line,and $160 full particulars. ~ 11 A built in a highly finis hed m ahogany cabinet Zenith fll' /1 r~~tTR~To-;;o-;p~~~N-:-De;'-F 1\ t 1332 South Mich igan Avenue, Chicago, Illinois Radio Corporation I Gentlemen:- Plea se send me illus tra t ed literature on Zenith R adio. Dept. F, McCormick Building . . \-= ~ I CHICAGO .. _ .-:""L . - __ \. .,.-:, ~~~-::r?~ .." 9h- ...1" 7' --;" ,'<" I N a me ...... " ...... · .... · .... · ...... •

~ - ~=-. J "'" I Add ress ______...... _...... , ...... -- 2 RADIO AGE-"THE MAGAZINE OF THE HOUR"

RADIO AGE 70,OOO! s THE forms for the February The Magazine 0/ the Hour issue are about to close it A looks as if 70,000 would be the (Established March, 1922) minimum press run for this month. Dealers' orders are still coming in Volume 3 FEBRUARY, 1924 Number 2 as this is written and most of them call for substantial increases over January. We are likely to need 75,000 copies. One Chicago magazine shop sold CONTENTS out its R..t\DIO AGE supply three times on January 7 and when our - Page distributor reached the store with The Reinartz Audio Regenerator______5 a fourth consignment of the J an­ By Felix Anderson. uary issue, thirty customers were waiting for their "Magazine of the A One Tube Heterodyne______7 Hour." That little loop store sold By John B. Rathbun. 900 copies in one day. Analogy of the Receiving Antenna______9 "Sold out clean" said a telegram from Montreal, almost immediately By Frank D. Pearne. after receiving the Jan uary issue . Interference Rejectors ______11 . Pawtucket, Rhode Island, next came By Felix Anderson. in with a telegram asking that their original order be duplicated. Long A N ew Tuning U ni L ______15 distance telephone calls, telegrams, By Frank D. Pearne. letters and personal visits from dealers steamed things up until the How to Avoid In terference______21 business manager had to telephone By J. V. L. Hogan. the printing house to put the forms The Superdyne Receiver______25 all back on the presses for a second run. How to lVlake a Battery Charger______27 We told you on this page of the What the Broadcasters Are Doing______29 Jan uary issue that this was distinc­ tively a reader's magazine and we P ickups and Hookups By Readers ______34 explained how we had attained a TroubleshooteL______40 prosperous success, practically on Corrected List of Calls______A3 circulation alone. Now we are go­ mg to tell you what made that With Wave Lengths. Ja~uary issue sell like peanuts at a CIrcus. I t was the article on "Tuning out In terference." I t was the best and most comprehensive article on the Radio Age is published monthly by subject thus far published. E. F. RADIO AGE, Inc. McDonald, Jr., president of the Publication office, Mount Morris, Ill. Zenith Radio Corporation, broad­ Editorial and Advertising Offices, Boyce Building, cast some kind words about the 500 N. Dearborn St., Chicago article from Zenith-Edgewater Sta­ FREDERICK SMITH, Editor tion WJ AZ and other stations fol­ FRANK D. PEARNE, Technical Editor lowed his example. That announce­ M. B. SMITH, Business Manager ment over the air introduced us to LOUIS L. LEVY, Circulation Director more than 20,000 new readers. Western A dvertising Representatives Their letters have been coming in BRUNS & MACDONALD -and their subscriptions. We First National Bank Building, Chicago thank the broadcasters and the Eastern Representatives broadcast listeners. We promise to E. V. HEVEY & COMPANY reciprocate by continuing to do our 17 West 42nd Street, New York City Telephone, Longacre 1698 best to print a good radio maga­ zme. Advertieing forme close on the 15th of the month preceding date of issue l MUed monthly. Vol. 3. No.2. Subscription price $2.50 a year. Ent~d as second-clai!S matter September 15. 1922. at the post office at Mount Morris. llUnols. under the Act of March 3. 1879

Copyright. 1924. by RADIO AGE. Inc. -Editor, RADIO AGE "T H E A I R I S FULL OF THINGS YOU SHOULDN'T MISS"

Eveready" Three" 4 1'2 volts, three distinct uses, Length, 4 in,; width, 1 Yo in, ; height, 3 in.; weight, 14 01;. At all reliable radio dealers. This "C" Battery is a Wonder Worker

OU can make the loud speaker respond in "How to Get the Most Out of Your 'B' Ywith a new fullness and naturalness of Battery," a booklet on "B" and "C" Batteries, tone. You can save money by adding months sent free on request. to the life of your "B" Batteries. These things you can do by using the new Eveready This triple-use battery can also be used as "Three" as a "C" Battery. an "A" Battery in portable sets. Light and full of pep. Its third use is as a "B" Battery You already have an "A" Battery for the booster. . filament and a "B" Battery for the plate. A "C" Battery is connected to the third element Use the Eveready "Three "-a tested prod­ of your vacuum tube, the grid, affording a uct of the world's leading electro-chemic;;!.} control that is marvelous in action on audio battery laboratory. It serves more radio uses frequency amplifiers. and effects more economies than any radio battery heretofore developed. As a "c" Battery the Eveready "Three" prevents distortion and excessive flow of If you have any battery problem, Radio current from the "B" Battery, lengthening its Battery Information Headquarters will solve life. It is a wonder worker that saves its it for you. Write G. C. Furness, Manager, small cost many times over. Connect it in Radio Division, National Carbon Company, your audio frequency amplifier and note the Inc., 202 Orton Street, Long Island City ~ difference. Full directions on the label and New York. '

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AiJtto TQAA/!RJRMFR A+ 8- 8-1' 8T A- -22~ _..--6792- Fitu« I. An isometdc sketch of the Reinarn Audio Retenerator, described in detail in the a«ompanyln, article. The circuit u'" a rewound ,.ciocoupie,

as a tunin~ inductance. RADIO AGE "THE MAGAZINE OF THE HOUR"

A Monthly Publication M. B. S1ll.ith Devoted to Practical Frederick A. Smith Publisher Radio Editor

The Reinartz Audio Regenerator By FELIX ANDERSON Technical Assistant, Radio Age

EARKEN 'ye Reinartz followers! Acting upon this principle, John Rein- sizes in the course of his radio experi­ Drag out the tool kit, count over artz, originator of the Reinartz circuit, ments. In purchasing the variocoupler H the radio budget, and learn how to and owner and operator of radio station get one in which the tube is not more make a set that will rattle the diaphragms lQP-evolved the circuit shown in Fig- than three and one-half inches in diam­ of your telephone receivers. ure 2. Instead of tuning the grid circuit eter, and which has a rotor la rge enough To make improvements and adapta­ with a condenser as was outlined in the to accommodate fourteen t urns of No. 18 tions on a good circuit is always in order. September,1922, issue of RADIO AGE by sse insulated wire, on each side of t he We are, therefore, presenting to our read­ Mr. Pearne, Mr. Reinartz substitutes a shaft. ers several new circuits and adaptations large variable inductance to accomplish The primary is wound in t he following of the Reinartz circuit which have this purpose. manner. Punch two holes in t he card· evolved since the original presentation The originator of this circuit claims it board tubing, and start winding, using of this system in June, 1922. is so much better than the original spider No. 18 sse wire. The first t en t urns are The original Reinartz circuit consists web system, that he advises those using tapped every turn as shown in the sketch of a spider web coil wound in auto trans­ the first system to give this new permu- in Figure 1. This winding should start at former fashion, with a capacity (con­ tation a trial. the end opposite the rotor of the t uner. denser) shunted across its grid circuit Construction After t he first ten turns are wound, com- inductance. It is a well known fact that To construct this set, it will be neces- plete the coil by winding 3S turns with­ an arrangement of this kind does not de­ sary to rewind a standa rd variocoupler. out taps, lea ving a n end suffi ciently long liver as great a voltage variation to the This is about the only dra wback of the for connecting purposes. grid of the tube as would an arrangement system, but it will be found that no dif- The rotor should then be rewound as comprising a large variable inductance, ficulty will be experienced by the a verage mentioned above, with 28 t urns of the making it unnecessary to use the capacity fan who has by this time become fa milia r same size wire, placing 14 t urns on each for tuning purposes. with winding coils of all descriptions an d ha lf of the rotor. AERIIJL 43PLJflF .oof MP 23pJ.nJ£ ,0005" i"1r I

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+ ~ IJB4T '----11/1/111111--+ _-6-----IIIIIIIII\I~+-~ BD fj4T h-301/ SA 811T 6712 V Figure 2-The wiring diagram for the Reinartz A lldio Regenerator. If it is found that the tube must be turned on dangerously high to make the set oscillate properly, a choke coil consisting of about six turns of the same size wire as is used on the tuner on a I-inch tube should be inserted at the point marked X . 6 RA.DIO AGE-"TH E MAGAZINE OF THE HOUR" AERIAL 36 7VRNS NO I6lXC ON 31N 7V8E

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REACTANCE {'OIL S;.JOULD BE WOUND IN RCVEI?S£ OIREC TlON 17J Cull L ~lll l jlllllllr-----, T 8BqT- 30-45"11. Figure 4-A nother permutation of the R einartz set with tuned radio frequency amplification. The accompanying article gives the necessary constants for building this set. The 45th turn on the stationary coil is condenser connected to the plate of the oscillation or tube howl. The condenser then connected t o the fi rst t urn on the second tube feeds back capacitatively the should be adjusted to a point where the rotor as shown at "A" o n t he isometric a udio currents of the second valve, very circuit is so called "triggered off," an in­ sketch. This puts the two coils in series, much in the same manner as the radio fre­ termediate point where the circuit is quiet very much like a variometer. quency is fed back to the antenna from and clear. The signals are as produced by Additional Apparatus t he plate of the first tube. It will be this triggering action clear, sharp and clean, and without "mush." For those who already have Reinartz noted that the grid condensers change The set will function with practically sets, very few additional pa rts other t han their capacities from the usual .00025 to any type of tube, but for the best results, the variocoupler will be necessary, but .0025 or .003 MF. This, with the open a U V 200 should be used with about 16 or for those constructing t he fi rst set of this low voltage connection on the audio 18 volts on the plate and coupled to the type, we are printing a complete li st of frequency transformer are practically the second tube which should be either a apparatus necessary. T he parts are : only depa rtures from the usual circuits. Mr. Reinartz claims tha t this permu­ WE VT 1 or other amplifying tube by 1 43 plate vernier variable condenser. tation is easily equa l to a t wo stage am­ an Acme transformer. 1 23 plate vernier variable condenser. Other Improvements 2 .0025 or .003 fi xed condensers. plifier if properly constructed and intel­ ligently operated. Through the Technical Office of thi~ 2 tube socket s. The a djustments of the 23 plate con­ magazine, the writer notices many re­ 2 rheostats, resistance depending on quests for different permutations of the type of tube used. denser control the tone of the signal, and Reinartz circuit with radio frequency 1 set of phone tip jacks. permits reception with ·unusual clarity. If, however, the condenser mentioned is amplification of the tuned type. Figure 1 dozen switch points. adva nced too far, the signal while ter­ 3 shows one type of circuit which is some· 1 switch lever. times effective in this respect. The con· 1 standard 4 or 6 to 1 audio frequency rifically a mplified will conta in an audible stants of the circuit are shown on the transformer. 4E/?IIJL 36 iURNS NO 16 O(C diagram, and need 'no comment. 5 Fahnstock binding post s. WIRE ON .3 INCH 7IJBE 2 standard binning post s. (Continued on page 48 ) 1 7x15 inch bakelite or fo rmula panel...... 0003 1 variocoupler fulfilling the speci fica- " tions aforemen tioned. Bus bar, mounting board, phones, tubes, batteries and other customary ac­ cessories. After the parts have been acquired, t he builder should arrange them on the pa nel a nd mounting board as shown in the R isometric sketch. If a single hole is drilled in the back of the cabinet, which should be of the hinged top type, a ll the battery wires may be run into the set through this hole and connected with ease to the spring t ype of binding posts as shown in the sketch. / The antenna a nd ground posts are of I _ 111111111--+--- more attractive design to preserve the __ GROUND 200-400/2 pd/liNrIOMETER. general appearance of the set. 8~ 16-8011 Operation Figure 3. T he Reinartz circuit in connection with the tuned impedance radio fre ­ The set makes use of the audio re­ quency method of low frequency amplification. This method is highly efficient in tuning generation principle, inasmuch as the over a broad band of waves. RADIO AGE-"THE MAGAZINE OF THE HOUR" 7 Single Detector Tube Heterody ne By JOHN B. RATHBUN OR the experimentally inclined normal oscillations in the detector­ have another condition of wave summa­ this pocket edition heterodyne re­ tuner circuit of a regenerative set, t ion. In t he super-het erodyne t he in­ Fceiver will prove exceedingly inter­ where (a1) is the "amplitude" or inten­ coming radio waves from the aerial a nd esting and instructive, and further still sity of the radio waves. Fig. 2 shows the waves from the local oscillator are can be made the nucleus of a full fledged the amplitude (a2) of the waves created slightly "out of phase" or out of step su per-heterodyne set should the builder by the local oscillator tube, and by a in order to gain a n interference which is decide later to add the necessary stages suita ble supply of energy to this tube commonly known as the " heterodyne of amplification. Properly constructed we can make the amplitude of the note" or "beat not e." It is by t his and handled, this baby of the heterodyne artificial oscillations several times greater method that we reduce t he high frequency family is capable of very good results, than the value of the incoming radio radio wave of t he broadcasting station particularly where there is much inter­ waves shown in Fig. 1. The separate to a lower frequency wave. ference between local broadcasting sta­ local oscillator tube can be adjusted to Let us say that our radio amplifying tions. Its selectivity is one of its crown­ give any desired wave length so that these transformers are adjusted for a maxi­ ing features. oscillations are very close to the fre­ mum amplification at a frequency of So much has been said of late on the quency of the incoming oscillations. 100,000 cycles per second, but t hat the working principles of the heterodyne and In Fig. 3 we have the oscillations from incoming radio waves from the broad­ super-heterodyne that it seems almost the oscillator tube impressed on the tuner casting station have a frequency of 800,- unnecessary to enter into anything more circuit and so that the radio waves are 000 cycles per second. T his cha nge of than a brief outline of the heterodyne in phase or in step with the waves of the frequency from 800,000 to 100,000 cycles theory at this point. The purpose of oscillator tube. The total wave result­ can be easily produced by the heterodyne the unit shown here is to adjust the tun­ ing from the two superimposed waves is method in which the independent local ing circuit to the frequency of the in­ shown by the heavy full curve and it will oscillator tube is made to impress a coming radio impulses and then to aug­ be seen that the amplitude of this wave frequency of 700,000 cycles in the tun­ ment these feeble waves by super-im­ (a3) is equal to the sum of the ampli­ ing circuit. The total or resultant fre­ posing other waves from a local oscillat­ tudes (a1) and (a2) and that the ampli­ quency in this circuit is equal to the ing tube upon the tuning circuit. The fication of the original incoming wave difference in the frequency of t he radio

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sum of the wave amplitude or wave in­ can be performed by adding another local waves and oscillator waves, or nu mer­ tensity in the circuit is then made equal wave to it. In the regenerative circuit ically: 800,000 -700,000 = 100,000 cycles to the sum of the radio wave intensity or "autodyne," the detector tube sup­ per second in the circuit. and the oscillation wave intensity. This plies the wave (a2) and amplification is Since the waves must be out of step in a way is quite similar to the method had to a lesser degree by the "feed-back at the two frequencies of 800,000 and used in feed back regenerative systems method." In our present system with 700,00(; cycles, the resultant wave is not where the plate energy is fed back in­ the separate heterodyne we can have the exactly equal to the sums of the ampli­ ductively into the secondary tuner coil increase due to the detector tube plus tudes but is somewhat less, and further­ except that a separate tube is used for the further increase due to the super­ more, the resultant wave of 100,000 this purpose. In fact, every regenerative imposed waves of the oscillator so that cycles is no longer a pure sinusoidal curve circuit is to a certain extent a heterodyne the total is much greater than before. but an irregularly shaped curve having in which the detector tube at once per­ In all these figures we have assumed several humps or peaks. In F ig. 4 we forms the functions of detector, oscillator all of the waves were in step or in " phase," show the oscillator wave (b) out of phase and amplifier. and that they were simple "sinusoidal" with the radio wave (a) by just enough Using a separate tube as an oscillator waves as delivered by the broadcasting to produce the resultant wave (c) of is far more efficient, however, than using station. This condition is best for the 100,000 cycles. Since the amplitude of the detector tube for this purpose for heterodyne having a single detector tube, the wave (c) is equal to the sums of the there is no interference between the three but in the super-heterodyne where we other two amplitudes at every point in functions when the separate oscillator are to reduce the effective wa ve length the length of the curve, we have a ba dly tube is adjusted to the proper point for­ at the output of the detector for ampli­ distorted "harmonic" which has a longer maximum oscillation. The proper fila­ fication in the following ra dio stages, we wave length than either of the other ment adjustment for two waves. oscillations is sel- When operating dom the best ad­ the single t ube cir­ justment for detec­ cuit we are operating tion or am plification, more nearly under hence the sin g I e theconditionsshown tube regenerative or by F ig. 3 with all "autodyne" cannot waves in phase or be expected to de­ nearly so, but when liver the maximum we use t he oscillator output when work­ on a super-hetero­ ing under all three d yne having subse­ principles. ~/G 4 quent radio fre- Fig. 1 shows the quency ampli fica- RADIO AGE- "THE MAGAZINE OF THE HOUR"

tion at low frequencies then we control our oscillator tube so that the wave systems are out of phase as in Fig. .1,. This is the only d ifference between our present single detector tube "baby" and the aristocratic super-heterodyne with two or three bushels of tubes. By use of the variable condenser which con-

coupler having the primary coil (P)_an d the secondary coil (S). The secondary coil is tuned by the variable condenser (Cl) in the usual manner. The filament battery is at (A) with the rheostat (R). So far, the circuit is that of any simple tube circuit. Plate current from the battery (R trois the oscillator tube, we can have grid leak (G). The tuning unit for wave i the wave systems either in phase or out length adjustment consists of a fixed (Contin1led on paf!,e 38.) of phase at pleasure, hence we can use the circuit as a plain heterodyne or super­ heterodyne at will.

SIMPLE SINGLE TUBE CIRCUIT . f A simple single tube heterodyne can L be made by introducing certain modi­ fications into the common feed-back re­ generative circuit so that the frequency of the plate circuit can be varied in re­ P/XED spect to the frequency in the grid cir­ COUPLER cuit. That is, the plate current is fed p + back inductively into the grid circuit in t he usual way but additional means of _B frequency control are introduced into the plate circuit. A variable inductance 2 such as a variometer may be used in series with the plate circuit or else a "tuned pl.ATe impedance" having an inducta nce coil COf/PLI/Vt; PHONEs" ( OUTPUT) a nd variable condenser can be inserted into the plate circuit. The latter is probably the more effective and will b e /$ IS used in the circuit described. if? GROUNO Fig. 5 contains the amplifier tube """'$'" FIG. 5 (T ) with the grid condenser (Kl) and RADIO AGE-"THE MAGAZINE OF THE HOUR" 9 Analogy of the Receiving Antenna By FRANK D. PEARNE UST how the signals from a broad­ tric bell circuit, which forms a complete feet will depend upon the frequency of casting station are received upon the path over which the current can flow, the current flowing through the con­ J aerial is somewhat of a mystery to with the exception of the button, at ductor, being greater for high freq uencies the average radio enthusiast. He knows which point it is open. At any time the than for the lower frequencies. This in­ that the aerial is a very essential part of button is pressed, the circuit is com­ ductive reaction tends to choke back the his receiving set and that almost any pleted, current flows and the bell rings. applied current, causing the current to conductor strung across the roof, or be­ The air, being a n insulator, will not let lag behind the pressure. In other words tween any high supports, will bring in the any current flow until an actual contact it supplies another form of resistance signals. is made between the two springs in the which is not encountered in direct cur­ He will study carefully the different button, by pressing on the knob. rent work. types of receiving sets to make sure that Thus it is easily seen that an aerial Capacity may be said to also be another he understands which is the best for his circuit, with its open end extending into form of resist a nce to alternating, or os­ particular needs and after it is con­ the air, does not supply a complete cir- cilla ting curren ts, although its effect is structed, he stretches a wire, or wires, tf/AXIMf/M negative as compared with inductance across the roof with hardly any thought POSITIVE" and by the proper proportion of each, the other than that of making it as high and effect of both inductance and capacity re­ as long as possible. actance can be neutra lized, or made zero. If he really understood just how the As the effect of capacity is very essential energy is received and just what action not only in the aerial, but also in the re­ takes place in this very important part of ceiver, the reader should have a very his apparatus, he might be able to greatly thorough understanding of its cause a nd increase the tone and quality of his re­ nature. If two conductors having con­ ception. However, very little informa­ siderable surface are placed very close tion on this subject is available and he to each other, but not allowed to touch, MA)(IMVM and direct electrical pressure is applied can hardly be blamed for following along N66-ATlVE in the same rut as his fellow fans. It is to them, current will flow for a very small Fig. 3 true, much has been written in regard to fraction of a second, after which it ceases long and short, high and low aerials, etc., cuit and consequently a direct current to flow. This is due to the fact that the but very little has been said in regard to cannot be produced in it. large surfaces of the conductors absorb how the aerial functions, excepting that A direct, or continuous, current can be some of the current, although the circuit it is a collector of electro magnetic compared to a stream of water flowing is not complete. The current, however, waves. , continuously through a pipe. The char­ will only flow long enough for the con­ Electrical Currents acteristics of an altern a ting, or oscillat­ ductors to receive a charge equal to the The fact is that a current of electricity ing, current are different. In this case in­ applied pressure, after which no more is set up in the aerial when electro­ stead of being continuous in one direc­ curren t can flow, for the pressure in the tion it starts at zero pressure, gradually magnetic waves cut through it, but as it GALVANOMETER PL47GS is merely a conductor ending in the air, rising to maximum, drops back to zero, which is an insulator, the question often reverses in direction, rises to maximum and comes back to zero, as shown in 8ATTERV Figure 3. This illustration shows what is known as one cycle and the number of ...----111..-.---· times it occurs in one second determines the frequency. While an alternating and BA7TERY an oscillating current are exactly the same, low frequency currents are usually referred to as alternating currents, while '------IllI ~ 1------' those of extremely high frequency are Fig. 4 called oscillating currents. In radio work, currents of very high conductors is then equal to the applied Fig. 1 frequency are used. For example, the pressure and opposes it. arises as to how an electric current can ordinary 360 meter wave used by many The size of the conductors, the distance flow in an open circuit. It is true (in the broadcasting stations, is produced by a of separation and the quality of the in­ case of direct or continuous currents) a current having a frequency of 833,000 sulating material between them (in this complete conducting circuit must be cycles and a 300 meter wave has a fre­ case air) will determine the amount of supplied before a current will flow and quency of 1,000,000 cycles. Such high current which will flow into them and when such a curciut is established, the frequencies can not be obtained with the length of time required for them to amount of current flowing will depend up­ ordinary alternating current generators receive a charge equal to the a pplied on the electrical pressure applied and the and are usually supplied by vacuum pressure. electrical resistance of the circuit. tubes, which can be made to oscillate at Use of Galvanometer Such a circuit is shown in Figure 1. If the necessary high frequencies. Figure 4 shows such an arrangement this circuit is broken at any point, the Resistance Governs Currents with a battery supplying the pressure current will cease to flow until it is again Now in alternating current practice, and a galvanometer connected in the cir­ completed. cuit. At the instant the current is ap­ In Figure 2 we have an ordinary elec- the amount of current which will flow in a circuit is not only determined by the plied, a slight movement of the galvan­ 8fTT{)}.J BEL L resistance of the circuit and the applied ometer will be noticed, showing tha t some pressure, but two other factors enter into current has moved in the circuit, although the consideration. These factors are this circuit is open (between the con- called inductance and capacity. In­ ductance is caused by the rapid changes Al.TffRNATINr;, C{JRREJIIT taking place in the circuit as the current CENERATOR l.INE rises, falls and reverses as shown in Fig­ 84TTE"RY ure 2. The effect of inductance is such M~T£R as to set up a reactive current in the '------tlIII------conductor, which opposes the applied Fig. 2 current in direction. This reactive ef- Fig. 5 10 RADIO AGE-"THE MAGAZINE OF THE HOUR"

ANTENNA

Figure 6 The magnetic li nes being at right angles to the electrical wave trd-vel in.a horizontal plane. d uctors, or plates). Now if the current capacity, it becomes a simple matter to ground as shown in Figure 6. The mag­ is quickly reversed, the pressure stored expl ain the a ction of the antenna. The netic lines being at right angles to the in the conductors will act with the cur· energy supplied to the aerial of the tra ns­ electrical wave tra vel in a horizontal rent of the battery, or applied pressure mitting station produces both electrical plane, cutting through the receiving adding its stored-up pressure to that of and magnetic effects. The electrical aerial as shown. As each cycle of the the ba ttery a nd the combined pressure wave is in the form of a strain between incoming wave reverses, the lines cut of both will flow through the gal­ the aerial and ground which is released through the receiving aerial, first in one vanometer in the opposite direction, un­ at each pulsation carrying with it the direction and then the other, produci ng til t he conductors become charged again. tiny magnetic lines of force which eventu­ in it, a current of the same frequency as Each time the current is reversed the ally reach the receiving aerial and in that sent out from the broadcasting sta­ conductors will be di scha rged a nd cha rged cutting through it, produce a current of tion. As each impulse is of extremely up again in the opposite direction and it will be seen that if an alternating, or oscilla ting current is a pplied to the con­ ducto rs, a t each cha nge in direction of current, a slight current will move, al­ t hough t he circuit is open. It is true tha t it moves for o nly a small fraction of a second, but it moved and that is the important t hing. The galvanometer will show that a sli ght current flows first in one direction a nd the n the other, as long as these reversals in current take place. T his action of the conductors, or plates, is due to the capacity for absorbing a cer­ tain a moun t of current in receiving a cha rge. Now it will be apparent that the larger the conductors and the closer they Figure 8. Water analogy of antenna capacity, with relation to wave length. a re together the more capa city they will have, causing the current to flow longer extremely low pressure in the aerial and short duration, the capacity of the aerial before they become fully cha rged. the primary coil of the receiving set should be enough to allow as great a Figure 5 represents a condition which which is included in the circuit. charge as possible, or in other words, very often occurs on alternating current The principle involved in the produc­ should be enough to allow it to charge circuits. An a mpere meter placed in the tion of this current is similar to that of completely with each impulse as previ­ circuit near the generator will show some the dynamo, in which the conductors are ously explained, in order that entire an­ current fl owing even though the circuit revolved in a magnetic field and made to tenna circuit may be made to oscillate is open a t the dista nt end. This is due cut through the magnetic lines of force. in unison with it. to t he capacity of the conductors ab­ I n the case of the aerial the lines of force As the magnetic lines travel in a hori­ sorbing and discharging current. are made to cut through the conductor. zonta l plane, most of the cutting takes Action in Antenna The electrical wave passes out into space place in the vertical part, or lead-in of After t his discussio n on t he subject of in the form of lines from the aerial to the the aerial, the horizontal part on the roof acting more as a capacity than as a re­ ceiver. In fact, if the flat part of the • aerial is the same height on both ends, no cutting of the lines through it will ., take place, as the lines travel in the same plane with it, but if the end farthest from the lead-in is slightly elevated, then some cutting of the lines will take place, al­ though the current produced in this part ---.;!!~.-- " wilI be slightly out of phase (later, or ahead) with that produced in the ver­ tical part, but it will be in the same di- rection. Effect of Height If, however, the distant end is con­ siderably lower than the lead-in end as shown in Figure 7, then the current pro­ duced in this part will be in the opposite -=r' direction to that in the vertical part and Figure 7. W rong cons/rurti on of antenna. The li nes rut in SItCh a manlier as to ut the result obtained will be the difference liP opposing rurrents. (Continued on page 44.) RADIO AGE-"THE MAGAZINE OF THE HOUR" 11 ------'------Interference Rejectors By FELIX ANDERSON Technica IAssista11 I,Radio Age

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J.IOIllEYCOMB (OIL 5"0 ~ 75" IVRN5 / 0-0kF (OIL lVl?;V5 SfF7r:1I BY 2,5""w FELIX ANDERSON NO 34 Dec ON 3 IN 1&'8£ RADIO 9DqS J Figure 4--The isometric sketch of the tube rejector, illustrated electrically in figure 3.

N THE J a nuary issue of RADIO AGE, from continuous wave stations. Broad­ of the mica type of the fo Il owing ca­ the writer gave some practical hints cast stations using tube transmitters are paCities: .001 MF, .002 MF, .003 MF, I on the construction of wave traps, included in the category of modulated and .005 MF. You will need several feet and eliminators, useful in tuning out in­ continuous wave transmitters, and the of bus bar for wiring, a suitable mounting terference from stations and other rejector shown in Figurc 1 is therefore board or panel or other arrangement to sources, which met with the approval of of material assistance in eliminating sig­ fasten this accumulation of apparatus on. many fans. The article, while describing nals from a station of that type. Drill a hole large enough for a shaft to in detail some of the more simple but The only disadvantage that this type mount the slider in the panel or mount­ nevertheless effective types of filters, did of rejector has, is its cumbersome and ing board as shown in Figure 1. If you not comprise two types which are of great clumsy construction, but the relative ef­ can acquire one of those porcelain gas value in eliminating interference, and ficiency of a system of its kind greatly stove handles such as is uscd on gas burn­ which a re of great help in el iminating sig­ offsets any constructional or mechanical er stop cocks, use it as a knob to vary the nals of disturbing nature. difficulties. slider. Drill holes large enough to fit the The writer reali zes fully that the aver­ Procure about four feet of very heavy small mounting screws to the panel age fan will not stop at expense or copper wire about the size used for street (which by the way should bc large enough trouble when it comes to removing this car trolley wire or larger, four switch lev­ to accommodate a fifteen inch circle of obstacle from his path, and wishes there­ ers, eight switch taps, about ten inches of thc heavy wire) at rcgular intervals a long fore to give detail on the construction of copper strip one thirty-second of a n inch the circumference of a circle of fifteen two more elaborate tYlles of so-call ed thick or heavier, one dozen small nuts inches diameter. rejectors. and bolts, a piece of brass eight inches The next step is a feat of strength. The first of these two rejectors is a sys- . long, one-sixteenth of an inch t hick and The heavy wire must be bent into a well tern widely used by the British Marconi about three-quarters of a n inch wide, two rounded circle of 15 inches diameter. Compa ny for tuning out interfercnce binding posts, a nd four fixed condensers Aftcr this has been done, it is carefully 12 RADIO AGE-"THE MAGAZINE OF THE HOUR"

as low a resistance factor with respect pedance to the frequency of that signal, to both alternating current impedance while to other signals on other frequen­ and ohmic resistance as possible. cies, the impedance is negligible. The A \Vhen the construction has been com­ signal not wanted is dissipated in the pleted to the satisfaction of the above wave trap or rejector, while other sig­ specifications, connect the post marked A nals which are not coming in on the same to the antenna, and Post B to the an­ wavelength pass through the rejector SIN6lE 7t.J(ftJ a=- flEAW tenna post of your receiver. It does not without resistance. SOUD COPIJ£R wIR£ The rejector may be connected into the 15// ;Y,QMETE"R antenna in the manner shown in Figure 5, page 6, of the January, 1924, issue of RADIO AGE, where it performs the same duties as outlined for the wave trap con­ nections of that article. / I t may not be amiss to again mention / / I \ 13 .001 .002 003 \ .OCJ.!,- that if results are to be obtained with this type of filter, the condensers must be of low loss construction, the connections should be rigid, and it is even a good plan to wire the rejector up with wire of as great a thickness as mechanical reason­ ableness will permit. A number 10 or 12 Figure 2-The wiring diagram of wire is not any too large, and a strip of the rejector, showing how the unit is sheet copper cut into a ribbon about 1-2 connected to the rest of the system. inch wide is vastly superior for connect­ ing purposes. sandpapered, and soldered rigidly to the make a particle of difference what type If you can convince yourself that a copper strips which are cut from the ten of circuit you are using so long as it uses clumsy affair of the dimensions given is inch piece of copper. The illustration an antenna of the open end type. This efficient enough to offset the appearance shows how this is accomplished. The circuit can be used with loop aerials, but and convictions that radio apparatus slider, constructed from the brass strip, the writer hardly deems it necessary to should be as small as possible without re­ should next be drilled and mounted so as use an arrangement of this type with a gard to electrical specifications, we cer­ to run smoothly over the entire arc. properly constructed loop. tainly recommend your constructing one Drill for the mounting of the switch lev­ The rejector is tuned very much in the of these rejectors. ers, and switch points and make allow­ same way as the ordinary wave trap is Vacuum Tube Rejector ance for the two binding posts. Two operated. Different settings of the The most elaborate of all the inter­ switch points must be used, one to throw switches controlling the condensers, and ference preventors, selectors and systems t he condenser into the circuit and the varying of the slider on the inductance to prevent interference as yet outlined in other out. will reveal a certain well defined point RADIO AGE is the radio frequency am­ When all the apparatus has been where the signal of the interfering station plifier-rejector, which requires more ap­ mounted either according to the above is obliterated. paratus than the ordinary detector cir- instructions or to the taste of the builder, The receiver is then tuned to any wave cuits now in use. . the instrument should be wired according except that to which the rejector is tuned. A glance at Figure 3 will reveal that the to the diagram shown in Figure 2. The The action of the rejector is the same as circuit is really nothing more than a isometric sketch of the rejector also por­ that of a wave trap, inasmuch as it con­ simple radio frequency amplifier which trays clearly the method of wiring up sists of a highly selective parallel tuned can be connected to the antenna and such a unit. circuit which is connected in series with ground posts of any of the conventional Solder all the connections, and make the antenna lead. The rejector when receiving sets now in use. The circuit is, sure that not a poor connection exists in properly tuned to the interfering wave by however, really more than that, due to the the set. The secret of the entire rejector the manipulation of the condenser fact that it contains in its plate circuit a lies in the construction to make it possess switches and slider offers a very high im- highly selective wave trap, which in con- HON£1/({}t18 roiL 40 TURN)

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Figure 3-The tube type of rejector is one of unusual merit, and fans who are looking for an elaborate but sure-fire eliminator should try the one described herewith. ------RADIO AGE-liTHE MAGAZINE OF THE HOUR" 13

Figure I.

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$.IIE7rH 8Y FRlx ANDERStJAJ ~~"J junction with the action of the tube and ferred) mounting board and other acces­ choke coil, acts as a highly selective tuner, sories. of the finest degree. The a rrangement shown, while spread apart to illustrate more clearly the con­ The action of the 23 plate condenser in List of Parts nections, can be used if the apparatus is the antenna circuit is a well known fac­ The necessary parts for the construc­ bunched closely, to make sure of short tor, inasmuch as many fans are already tion of a unit of this type are rather many leads, so necessary in the construction of aware of its value in tuning. This con­ when one considers that it is merely to radio frequency apparatus. If the builder denser in connection with the honeycomb be used as an interference preventer, but desires he may use his own judgment as coil used as an inductance, form a pre­ one should remember that in addition to far as arrangement is concerned so long liminary tuning circuit much similar to its being a boon as far as selectivity is as he observes carefully the rules regard­ ing the construction of radio frequency the one described under the title of simple concerned, it is a simple radio frequency units. series eliminator in the January issue. amplifier of e fficient design. The parts necessary a re: Together with the action of the tube, The construction is largely a mattcr of 1 7xlO inch panel. personal choice of apparatus, and know­ which further increases the sharpness of 1 23 plate condenser vernier type pre­ ing that amateurs rarely work to given tuning, it is in ~tself a circuit from which ferred. dimensions, we refrain from printing average selectivity may be expected. 1 43 plate condenser vernier type pre- template instructions or definite measure­ The insertion of the forty turn honey­ ferred. ments. comb coil and 43 plate condenser in the 1 50-75 turn honeycomb coil. The size of the honeycomb coil in the 1 40 turn honeycomb coil. plate circuit further removes the ob­ antenna circuit is largely dependent upon 1 rheostat. the size of antenna, and a little ex­ noxious interference, which we are trying 1 200-400 ohm potentiometer. perimenting with coils of different sizes to eliminate, and this, together with the 1 tube socket. will soon determine which is the proper tuning qualities of an efficient receiver, 1 radio frequency choke coil wound to size to use. forms probably the most surefire method specifications. The choke coil is probably the only to rid one's self of what the amateurs 8 binding posts. difficult thing to make (here is where the term "QRM." Bus bar, tube (Western-Electric pre- (Continued on page 38.) I-"....

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an ideal beg,inner's receiyer. RADIO AGE-"THE MAGAZINE OF THE HOUR" 15 The Old Reliable Circuit With Newr Tuning Unit By FRANK D. PEARNE

ANY of the old time circuits, to move in the same pla ne as the sta­ ing the panel arrangement and layout of the ones which we used to build tionary coil. making a coupling between the parts. This can be any convenient M in the old days when broad­ t he two with a flat magnetic fi eld a nd by size of panel and baseboard to suit the casting was hardly known, have proved this method, the lines of force are con­ cabinet which the builder can obtain. their value over and over again and if the centrated, instead of being spread out. Figure 2 is a schematic arrangement of truth were known many of the supposed­ Because of this concentration, the lines the circuit showing a list of the necessary ly new and intricate circuits of the last do not penetrate to the other parts of the parts and their different values. year or two are merely additions, or re­ set a nd cause such disturbances as howl­ T his circuit in use in Chicago has been arrangements of these old-timers. Some ing, nor will they waste t h eir own energy. picking up California and all distant of these changes are for the better and The tuning arrangement shown in the points in America. The circuit is not some for the worse, but the origina l basic drawing was originally invented by Mr. unusual and has been thoroughly tried principles are still there and m ay be Carl Pfanstiehl, president and engineer out and can be depended upon and the easily recognized if the circuit is care­ of the Pfanstiehl Radio Service Company, total absence of any dielectric material fully analyzed. back in the early part of 1923, a nd as it in the magnetic field, eliminates loss of One of the most popular improvements has proven such a success in thousands energy through dielectric absorption, was the substitution of the spider web of sets produced by him, he has consented a nd in the reception of distant signals. coil instead of the large variable induc­ to show his method to our readers. This This point is of the most vital impor­ tances previously used. The principal sliding method of adjustment can be tance. advantage of such a coil is the reduction a da pted to any of the popular circuits of the distributed capacity which is where the space is limited and will be present in straight layer windings. Dis­ found to give very close and sharp MacMillan's Messages tributed capacity acts like a n extra tuning. An absurd newspaper dispatch was load connected across the terminals of In the circuit described, the movable published recently to the effect t hat the the coils, using up much of -the feeble coil is- included in the plate circuit, a nd Aerial League of America was urging energy received upon the aerial and any­ acts as a feedback, ma king the set regen­ radio operators to check up and try to thing which tends to reduce it, is sure to erative, a n d as by this method its posi­ determine why Dr. Donald B. Mac­ improve reception, especially in the tion can be cha nged so minutely that the Millan's radio messages "had not been reception of signals from distant stations. amplification by regeneration can be heard in Canada and the United States." However, until recently no very con­ controlled to a very fin e point, which is so One Chicago daily gave the "story" quite venient method of adjustment has ever necessary in getting long distance recep­ a play and other papers in various parts been applied to such coils a nd the mount­ tion. The 23 plate condenser in the of the country gave it space. ing and adjusting arrangement was aerial circuit will also help to a marked usually left to the discretion of the build­ degree in bringing in the distance. It apparently had escaped the notice er and as might be expected, most of them While a carbon rheostat is shown on of all these editors that practically every were marvelous feats of engineering. the panel, merely for convenience, any newspaper in the country for several Nearly all the adjustments were obtained standard rheostat will answer the pur­ months has been publishing items about by swinging one coil away from the other pose very nicely. The phone condenser reception of messages from Dr. Mac­ at right angles, the movable coil being is used to by-pass the radio frequency M illan. Interesting accounts of how mounted on some sort of a hinge which current, which cannot get through the Jack Barnsley had received and relayed unless very carefully made, would not highly re-active windings on the phones. many messages from Canada to the Unit­ give the same aqjustment two times in Any standard detector tube may be used ed States have frequently been printed. succession. a nd the fil a ment battery selected will be Denial of the Relay League's aston­ In the circuit shown in the accompany­ determined by the type of tube used. ishing suggestion was slow in overtaking ing drawing, the movable coil is made Figure 1 is a n isometric drawing show- the original misstatement. On Decem­ ber 17 Kenneth B. Warner, president of the A. R. R. L. effectually spiked the yarn. President E. F. McDonald, Jr., of the National Association of Broadcast­ ers also sent a statement broadcast, show­ ing that communications had been re­ ceived regularly in both the United States a nd Canada.

L€6END f AERIAL 2 23 PLA7E VERNIER CONDENSER 3 SWITC/-I & SWI7CH7AIJS 4- GROUND 5" TUNING UNIT 6 6RIO LEA/<-i-3I'1c(fONMS 7 61

"NERK!" ~ ------~------, engineers to be a great accomplishment, giving a transmitting radius of ap­ ASHINGTON, D. C.-With the proximately a mile a pound. This is very materialization of the plans for light in comparison to the radio apparatus W the polar trip of the naval air carried by surface vessels of the navy. cruiser, "Shenandoah," or the ZR-1, it The after-section of the control car will has been decided that her original 300- be used as the radio shack. Some dif­ mile radio equipment first described in ficulty in locating the radio compass these columns last July, is inadequate where it will be operative and yet not and a brand new transmitting unit good hinder the progress of the airship and for a thousand miles has been developed interfere with landings is being en­ by naval radio engineers. countered, but this problem will be solved If, late in July or August, fans pick up soon, radio experts declare. the call, NERK, they may shout with The plans call for the use of two-base glee, for it will be the "Shenandoah" ships in the far north, each of which will communicating with one of the far­ be outfitted with a mooring mast and northern radio shore or ship stations. carry radio apparatus for communicating with the "Shenandoah" when she is on Radio equipment plans for the "Shen­ voyages. One of these remodelled tank­ andoah" include two transmitting sets, ers will be sent to Point Barrow, 70° two receiving outfits and a radio compass. north, and the other will in all probabil­ The high-powered set which replaces the ity be dispatched to Spitzbergen, where six fifty-watt tubes, includes two 2-kw it is hoped a temporary radio-compass tubes, with an input of 4 kw, and an out­ station can be established. Two other put of 2 kw. With this transmitting portable radio-compass stations will also set it is believed several northern radio be erected as far north as they can be stations such as exist in Iceland, Green­ pushed. With the two ship.s, this will give land, Spitzbergen and Russia, or our own the "Shenandoah" five radio compass Alaskan stations, can be reached. With stations of her own from which to check the powerful receiving sets Annapolis, her position and progress toward the top Cordova, Lafayette, Nauen and other of the world, even if she fails to pick up high-powered stations can be copied, or existing radio stations. used as points to establish the position of the great airship by means of the radio As has been pointed out previously, compass. This instrument is now be­ radio will enable the navy to check the lieved indispensable on this exploration position of the airship and if the pole is trip from a base at Point Barrow, Alaska, reached to prove it conclusively by cross 1,117 miles south of the Pole. bearings made aboard. Her positions could be rechecked later by northern Besides the high-powered transmitting stations having radio compasses. This set, an auxiliary medium-range tele­ eliminates faking of a position not at­ graph and telephone set is to be installed "Radio Dare-devil" tained and is a new feature in polar ex­ aboard the aerial cruiser. The telephone Major Edward H. Armstrong, of ploration made possible by radio. Since feature will be utilized for communicating New York, is here shown with a six­ the Arctic summer is barely two months with ground stations when landings are bulb suitcase receiver. The major is in length, and daylight is believed a neces­ being made for the immediate transmis­ seen in summer attire because he was sary requisite in this venture to the Pole sion of orders to the ground crew or op­ snapped at Palm Beach, Fla., where by air, speed in establishing the tempo­ erators at the mooring masts. he went for a honeymoon. Mrs. Armstrong was Miss Marian MacIn­ rary radio stations in the north is neces­ All the radio equipment weighs is 1,023 nis, of Merrimac, Mass. It was Major sary, so that the airship need never be pounds, which in itself is believed by Armstrong who applied the rej!ener­ out of touch with main and auxiliary ative principle to radio circuits. bases.

_.,

AERIALS AND CLOTHESLINES Picturing the back of a row of tenements near Jackson Avenue, Long Island City, where the tenants are not permitted to string aerials on the roofs. To overcome this objection, a young forest of backyard poles in competition with wash poles serve as aerials for the radio enthusiasts. RADIO AGE-"THE MAGAZINE OF THE HOUR" 17 Crystal, to Tube, to Loud Speaker A Two Stage Audio Frequency Amplifier to Use With Selective Receiver Described in January Radio Age ByJ.A.CALLAHAN

N LAST month's description of a se­ possible; resistance, inductance or trans­ If the four-prong jacks are preferred, lective tube receiver, evolved from former coupling. \Ve are offering herein they can, of course, be employed. I our original crystal detector circuit the latter method as affording the great­ Filament control jacks can be employed of the December issue, we have consid­ est degree of increased volume. and do not differ in construction from ered merely what may be regarded as the Transform>ers essential processes of reception. other standard types of jacks, with the The response of all methods of recep­ In selection of transformers preference exception of two additional prongs for tion can be further improved by straight­ should be given to those types which are filament which act in the nature of a forward amplification. shielded. In view of the low cost of these switch contact to connect A battery to We conceive the most simple to be that units a discussion for their construction filament of tube to be employed. This method which deals with amplification of does not seem necessary. T he proper method relieves the necessity for filament low frequency currents which is called, for ratio is a six to one on first and second current switches for detector and ampli­ obvious reasons, as previously discussed, stages respectively. It is advantageous fier tubes. It eliminates switches be­ audio frequency amplification. Radio to connect the second stage of amplifi­ tween amplifiers and between amplifier frequency currents are by no means as cation as a push-pull type. This method and detector. It is a saving of filament simple of control and tae perfection of the was described at length in the January current which under customary opera­ type of amplification under discussion is issue of RADIO AGE with a presenta­ tion is wasted by leaving tubes burning advisable before any attempt at the other tion of its v irtues. while not in service. It simplifies the is assayed. Switches or jacks are usually provided operation of the receiver. Pushing in the The method consists essentially of a for connecting the telephones either in phone p lug connects the receivers to cir­ cuit of detector or desired stage of am­ series of audion amplifiers arranged elec­ the plate circuit of the second tube for trically so that the amplified output of full amplification or in the plate circuit plification and lights the tube or tubes all each tube is passed on successively to the of the first tube for the use of a single in one operation. An added convenience is found in that once the proper adjust­ next to be again amplified. Each tube stage. In the diagram pictured, jacks are with its passing-on coupling is referred shown a nd are of the three-prong type ment of rheostat is obtained it will re­ main constant. A diagram showing con­ to as a stage, or step in the amplifier. which are preferred by the writer because As magnification of tube and battery they are more simple to connect, having nection of this type of jacks is offered for your convenience, should they be pre­ noises, and other disturbances of this na­ one less contact as a source of disorder. ferred. ture, is proportional to the magnification This method of jack connection allows of the signal received the number of one side of primary to remain connected As advised for our detector, or tuning audio frequency stages which are ad­ to circuit; however, with audio frequency unit, in the January issue we are still visable are two, possibly three. current there will be no disadvantage of adhering to the preference for six-volt Several methods of linking tubes are dead end or capacity losses. tubes in this unit, those known as am-

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B DnT-r 18 RADIO AGE-liTHE MAGAZINE OF THE HOUR"

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+--- +- GROVND Ilallll tllsll\lll\ 2.2. 'Ii VOLTS 90,/0'-1S plifier tubes, which differ somewhat from volts if effective and if over fifteen volts is his hand, often negleGting to make a the detector tube. registered it is shorted. ground connection, and listens in. Dry Cells Locatin~ Troubles To be sure, he takes what he gets-the The smaller t ubes can be used, with If signals are without amplification nearest and strongest station on the air. dry cells, without necessItating any look for a dead B battery or defective The vest-pocket set comprises a single change in the circuit, with the possible ex­ transformer. head phone, without leads, and a fixed ception of rheostat resistance. If no signal is received look for lack of crystal detector, connected in parallel The U V 201a or C 301a are recom­ contact of jack or for disconnected B with the phone by two short copper mended. battery. wires from the telephone terminal. The resistance of rheostat depends Distorted signals result from inoper­ Placing the phone to one ear and making upon the tube employed and is rated as ative C battery or defective transformer. contact with as good an aerial as he can given in the accompanying t able. Now that we have offered you a se- find conveniently by means of his fingers, which of course must touch one of the W D 11-12 tube. __ ...... 6 ohm rheostat NP Ihr I~f c , two terminals, is all he has to do. By U V 199 and C 299 .. 20 to 30 ohm rheostat Jnc'i' UV 201a and C301A ... ~ ...... this means he has heard NAA time ...... 15 to 20 ohm rheostat signals and set his watch, and also whiled UV 201, C301 and 216A ...... away odd minutes by listening to WRC ...... 4 to 6 ohm rheostat or WCAP when they were on the air. A "C" battery is advisable because of One day he picked up KDKA. When the resulting economy of B battery cur­ convenient he also makes a ground rent and is particularly advantageous in connection at the other phone terminal, increasing volume if the peanut tubes are but he says it isn't always necessary. used. This should be four and one-half The particular crystal he uses is a com­ pact unit about the size of a short thick \"olts, regardless of type of tubes in circuit. L..---+-_--i--~---_+_- +R B battery connection is indicated in dia­ lead pencil with binding posts at each -f] gram a nd plate potential can be from end convenient for connection with the sixty to 100 volts. lective tuner and an efficient amplifier you phone terminals. He used to use a tuner Difficulties may be encountered in per­ a re going to experience the added joy but as this bulky apparatus didn't im­ fecting operation of the amplifier. Some­ of general participation in the high qual­ prove incoming signals he discarded it times transformers are defective, often ity of entertainment being broadcast, as' he also did his phone leads and wires through being damaged in shipment. A rather than that which is limited to the for connecting with aerial and ground. simple test by which condition can be phone method of reproduction, and there The result is believed to be the neatest determined is e mployed by connecting need be no scramble a nd argument in cheapest and smallest portable set in use. t he primary of transformer in series with your generally peaceable family as to "whose turn it is to listen-in" because a 22Yz volt B battery a nd a voltmeter If your newsdealer has sold 0 u t which has a reading of from 25 to 50 you are justified in adding a loud speaker his supply of RADIO AGE you arc volts. Depending upon the make of to your equipment, knowing that it will likely to miss just the hook-up that transformer, the reading of voltmeter afford a highly satisfactory performance. you have been lookin~ for. To should be between ten and eighteen volts. avoid any such chance fill out the If the meter registers over twenty volts Tiny Receiver coupon in this issue and send in your the transformer is shorted. If it does not Harold Lane, one of the Washington subscription. Then you will be safe. register at all some connection is broken correspondents has what is believed to And don't for~et that with each and in either case the transformer is not be the simplest complete ra dio receiver subscription at the special price of serviceable and must be replaced. yet assembled. He carries it in his vest $2.50 a year, we send you free the The secondary of transformer is tested pocket, phone a nd all. When he is near popular Reinartz Radio boo k 1 e t in the same manner. The volt meter in anything which wiIl serve as an antenna, FREE. Address Radio A~e, 500 N. this testing should read from five to ten he makes a contact, sometimes only with Dearborn Street, Chica~o, Ill. RADlO AGE-"THE MAGAZINE OF THE HOUR" 19 Interesting COlllbination Receivers By R. H. LANGLEY . Radio Engineering Dept. General Electric Company NE of the most fascinating things 1-3 cell F lashlight battery for bias, and describe them so that the possibili ­ about Radio is that it provides 41-2 V ties of the various combinations may be O such a fruitful field for experiment. I-Homemade loop antenna seen. The art is young, and there are many 6~Rad iotron s, UV 201, UV 201-A Let us divide the 18 circuits into five questions yet to be answered. The or UV-199 classes. a pparatus for the study of these prob­ -Outdoor a ntenna and ground First, on the outdoor antenna with­ lems is already planted in millions of connection. out radio ampli fication. American homes, and this paper is ad­ The loop will consist of 8 to 10 turns of Second, on the outdoor antenna with dressed to those who find pleasure in a lmost any kind of copper wire, wound radio a mplifica tion. trying new circui t combina tions. at 3-8 or 1-2 inch spacing on a wood Third, on the loop antenna. With a small selection of the standard frame 3 or 4 feet square, a nd arranged Fourth, using both the outdoor apparatus, it is possible to arrange so that it may be rota ted on a vertical antenna and the loop, and many interesting new combinations that axis. Fifth, some special arra ngements. a re not given in the instructions. I In all the circuits to be described, a In the first class, that is, on the out­ shall give now a list of the apparatus UV 200 soft detector tube may be used, door a ntenna without radio amplifica­ needed for the combinations to b e if suitable a rra ngements are made fo r tion we can list seven different combina­ described later, and it might be well to obtaining the correct plate voltage. tions. Two of these regenerative; the make mental note of the items which Eighteen Circuits other five circuits are not regenerative. you do not have. \Vith the a pparatus just enumerated, This, of course, means a great deal in 2-Single circuit regenerative tuners there are at least 18 different receiver signal strength, particularly on the more I-Vacuum tube det ector a nd 2 circuits possible. Some will be very distant stations, but for the sake of mak­ stage amplifier sensitive, some highly selective a nd some­ ing the list clear and easy to remember I-Three stage radio amplifier both selective a nd sensitive. Some will we will take them a ll together. I-Variable air condenser be suitable for use in congested districts, The seven circuit arrangements pos­ 1- 6 Volt storage battery or some will f unct ion best for nearby sta­ sible on the outdoor a ntenna without 6-No. 6 dry cells tions a nd some for distan t sta tions. It radio amplification are as follows : 4-Blocks of plate battery, 22 1-2 is not possible of course to give diagrams F irst, single circuit tuner, using volts each of t hese circ ui ts, but we can classify crystal detector.

LONDON AND LOS ANGELES Mr. Kennedy is here shown pointing out the vernier rheostat on his simple three tube honeycomb regenerative set. He does all his tuning on this rheostat and on the secondary condenser. He gets Los Angeles and London. See photograph on next page. (Kadel & Herbert.) 20 RADIO AGE-"THE MAGAZINE OF THE HOUR"

Second, single circuit tuner with and from this to the detector audio with the result that considerably greater vacuum tube detector amplifier. amplifier. The second combination, amplification is obtained with the same Third, single circuit tuner, with which by the way is a very interesting or even better quality of reproduction. detector amplifier and the regener­ one, provides a method for using the With the UV-201, UV-201-A or UV-199 ative connection. loop in a regenerative circuit. This radiotrons, the plate voltage may be Fourth, using the outside condenser uses the loop a nd one of the single cir­ increased to 90 or 110 volts. to make a two circuit tuner. cuit tuners, then the radio frequency Aerials and Tuning Fifth, using two tuners to make a amplifier and the detector amplifier. There are many people who imagine two circuit tuner. The fourth class uses the antenna and that the loop antenna is a substitute for Sixth, using two tuners to make a the loop in combination. There are also the big outdoor aerial and that the same three circuit tuner and several possibilities here. The best one, results can be obtained from either. Seventh, using two tuners and the perhaps, consists in connecting the This of course is very far from the external condenser to make a an tenna a nd ground to one of the si ngle truth. There is a very fundamental three circuit tuner, with a ll three circuit tuners. The loop and variahle a ir difference. The aerial is a condenser. circuit tuned. condenser are connected to the three I t is a very large condenser to be sure, There are two ways of using the stage radio amplifier and the detector so far as its physical dimensions are con­ external variable air condenser to make amplifier in the usual way. These a re concerned, but it does not have a very a two circuit tuner. 'vVe may connect two independent circuits, the only con­ large capacity. the variable condenser across the tickler nection between them being that the The loop, on the other hand, is an coil to make a secondary circuit or we tickler coil in the tuner is connected to inductance. This means that the method may connect the condenser in series with the tickler terminal on the detector of tuning the aerial is quite different the tickler coil to make a primary amplifier. This combination is quite from the method for the loop. The same circuit. rema rkable in performance. The an­ recei ving sets will not wor k in terchange­ In using two tuners to make a two tenna circuit is brought into reso nance ably on either. The single circuit circuit tuner the tickler coil of the first with the signal by means of the tuner tuners are suitable-for tuning the antenna, but when we used the loop, we used a separate variable air condenser to tune it. In these experimental combination receivers, it makes very little difference which tube we use. The main difference between the various tubes is in energy consumption in the filament, rather than in performance as detectors or ampli­ fiers. Some are slightly better than others in this respect, but the main purpose of the newer types is to simplify the A battery problem. The UV-200 and the UV-201 require 1 ampere fila­ ment current necessitating a storage battery. This is expensive and trouble­ some and requires frequent charging. The UV-201-A takes only 1-4 of an ampere and can be operated four times as long on one charge of the battery. It may also be operated from dry batteries. A DISTANCE GETTER The UV-199 tube takes only 6-100 of an ampere and can be operated from dry Thomas J. Kennedy, 470 West 159th Street, N. Y., regularly receives 2-LO, of London, Eng., and KHJ, Los Angeles, with this simple three-circuit batteries with great success. honeycomb regenerative set. He tunes with the secondary condenser and the rheostat of the detector tube, without moving the honeycomb coils Radio "Help Wanted" or the ground condenser. Note how he uses condensers and grid leaks The Government is advertising by across the transformer secondaries to clear up signals. (Kadel & Herbert.) radio! But. although direct radio adver­ tising is banned, there are few who will tuner is used as a coupling coil and con­ and the loop circuit picks up energy object, since the results achieved seem nected to the input terminals of the from this tuner antenna circuit. The to indicate that the public is benefited. second tuner. reactions obtained by the tickler coil Every Wednesday night, Mr. Morgan In using two tuners to make a three connection make it possible to success­ of the Civil Service Commission, broad­ circuit tuner, the two tickler coils are fully eliminate very loud nearby stations. qsts from NAA, Arlington, openings in connected together to form the third I n the fifth class, let us notice two government positions and announces or link circuit. If we connect the stunts. The first one consists in amplify­ examinations to be held for every kind variable air condenser in series with ing the signal obtained from the crystal of a job from that of an unskilled laborer the two tickler coils, we can then tune detector, by connecting in such a way to those requiring highly trained scien­ this intermediate circuit. that the output of the crystal detector tists, statisticians and executives. Some The second class of circuits were those goes thru the primary of the first audio replies indicate direct results, but as not on the outdoor antenna with radio ampli­ frequency transformer. No batteries all applicants state how they learned of­ fication. For these we use our three stage are needed in the crystal detector cir­ the openings, an exact check is impossible. radio amplifier and insert it between the cuit. This is a very fine way of obtain­ The recent call for apprentices for the tuning system and the detector amplifier. ing excellent loud speaker signals from Washington Navy Yard, however, This may be done on any of the seven nearby stations. The second stunt, brought several phone calls and mail combinations which we have just noted is the use of a grid bias and a higher inquiries from fathers and mothers inter­ except possibly with the crystal detector. plate voltage on the amplifier tubes. ested in securing first class training for Loop Antennae Open the grid circuit and insert a small mechanically inclined sons. In the third class we use the loop Flashlight battery of say 4 1-2 volts The openings annually announced antenna. There are several combina­ between the grid and the filament bus. over the radio phone cover as many as tions here; let us notice only two. The negative end of lsiasing battery 1,000 different positions, Mr. Morgan The first is the straight loop circuit where should be connected to the grid and the states, and he is anxious for those seeking the variable air condenser is connected positive end to the filament bus. It is Government work to listen in Wednes­ across the loop and then connected to then possible to use very much higher day evenings at 7 :25 and learn what is the three stage radio frequency amplifier plate voltage on the amplifier tubes, available. RADIO AGE-"THE MAGAZINE OF THE HOUR" 21

DON'TB£ ASQEAL HOUND. £~ff #.{d,

CRUSADERS These radio fans are sure that they can induce others not to interfere with the enjoyment of neighbors by mak­ ing their regenerative receivers squeal. Miss Helen Dickinson, (seated on table) is getting the signatures of New York neighbors to an anti-squeal pledge. (Kadel & Herbert.) How- to Avoid Interference By JOHN V. L. HOGAN The seventh and eighth of this series of I suppose that accounts for the fact that ably expect to be able to listen to anyone radio talks, which have attracted wide most of the letters I have received ask, of the four local stations WEAF (610 kc ), attention, were presented through Station in one way or another, for remedies that W]Z (660 kc), WOR (740kc) or WHN (833 WEAF, New York, by Mr. Hogan, con­ will prevent hearing speech or music from kc) without any interference from any of sulting engineer and past president of the one broadcasting transmitter while listen­ the other three at any time. Many people Institute of Radio Engineers and author ing to another. In any event, this kind living in the middle West Side district of of "The Outline of Radio." of interference is wholly or partly spoiling New York have apparatus with which they T IS possible to classify the six the broadcast reception in many homes are unable to hear any stations other than things that give the most trouble, as today and it is doubtless the first that W]Y or W] Z when those transmitters I follows: we should study in detail. are working; but this trouble is not 1. Nearby broadcasting stations There is one very good thing about this hard to cure, for there is no insuperable using wave frequencies close to "crosstalk," as we may call it, and that difficulty in getting a receiver that will that which it is desired to re­ is that it can be very nearly if not entirely bring in long distance stations such as ceive. eliminated by rearrangement of your own KDKA in Pittsburgh and W]AZ in 2. Radio telegraph transmitters of receiving apparatus. Of course, you Chicago even when installed within only the spark type. must be reasonable in what you expect a few blocks of W]Y and W]Z. 3. Oscillating receivers that pro­ from any radio receiver; it would hardly Depends on Receiver duce whistling noises. be fair for a man who lived only a few The whole matter of eliminating inter­ 4. Distant broadcasting transmit­ blocks from WCAE in Pittsburgh to ference from one broadcasting station ters that radiate waves having expect his receiver to pick up signals while listening to another comes down frequencies within a few kilo­ from KDZE in Seattle without inter­ to the choice of your receiver. There are cycles of the frequency being ference. That is because WCAE sends two rules to guide this choice, as follows : received. out a wave of 650 kilocycles and would 1: The nearer your receiver is to 5. Atmospheric discharges, known be heard very loudly, whereas KDZE any broadcasting station, the more as "strays" or "static." sends at 660 kilocycles (only 10 kilo­ highly selective it must be to pre­ 6. Induction from lighting, trolley cycles higher) and would produce very vent interference from that station. or power systems. weak signals at Pittsburgh. On the other 2: The greater the distance you Of these six kinds of interference, the hand, this Pittsburgh. man might very desire to receive, and conseq uently first, second and third are the most bother­ fairly expect a good receiver to cut out the more sensitive your receiving ap­ some. Perhaps this interference from near­ WCAE at 650 kilocycles (even though paratus is, the higher its selective­ by broadcasting stations is not so great a very near to him) while he listened to ness must be to prevent interference. difficulty as is interference from spark WOR in Newark at 740 kilocycles, to Thus you will see that a receiving set transmitters, but where it does exist it WEAF in New York at 610 kilocycles. which is perfectly satisfactory in one is practically continuous whereas spark In the same way, anyone living any­ location or for one service may fail utterly interference at worst is only intermittent. where in or around New York may reason- when used in another place for another 22 RADIO AGE-liTHE MAGAZINE OF THE HOUR" purpose. Radio receiving is very em­ cannot "tune it out" sufficiently well to have little more to do with it than with phatically a matter in which one man's listen to the first. Perhaps they can the making of a man. People in your own meat may be another's poisQn. I t may adjust their receivers so that the inter­ neighborhood, using relatively inexpen­ be helpful, though to consider a list of ference is no louder than the speech or sive outfits of good desigll, are cutting twelve types of useful radio receivers music that they desire to hear, but it is right through interference that is troub­ arranged in the approximate order of still there and is intense enough to give ling other folks whose sets, in spite of their selectiveness, and I will give you all the discomfort of "getting the wires their higher cost, are poorly laid out. such a list tonight. If your receiver is at crossed." Last week I listed twelve general types the bottom of the list, don't let that If you are experiencing this sort of of radio receivers, in the order of their fact disturb you, for if it is sufficiently difficulty-and I know that thousands selective ability. Nearly every set now selective for your purposes, well and of you are-make careful note of these in use falls into one of these twelve good. But even a receiving set that is two points: classifications. If your set is low on the rated half-way up the list might not be First: The trouble necessarily lies list, and if you suffer from cross-talk good enough for some locations, and in in your receiver, for the wave fre­ interference, perhaps you will have to get such cases the only two remedies are quencies of the broadcasting stations a more selective type before you can cut either to pass the set along to someone are far enough apart to permit rea­ it out. The probabilities are, though, else who can use it and to get a new outfit sonable freedom from interference that your set is not as good as it should of better selectiveness, or else to improve in any location. Such interference be even in its own type. Therefore t he original receiver. Here, then, are is not the fault of any broadcasting your first step shoilld be to make cer­ twelve types arranged in the order that I station nor of the assignment of tain that your outfit is of good design. believe puts the most selective outfits wave frequencies. Spark Transmitters Second: Either your receiver is of a t the top and the least selective at the Before we go into the practical things a type which cannot possibly have bottom: that can be done to improve receiver adequate selectiveness for elimina- 1: Superheterodyne with closely selectiveness let us give a moment to t uned intermediate amplifier. the second worst kind of program­ 2: M uItiple-stage tuned radio f re­ smasher, which is the spark radio-tele­ q uency amplifier with regeneration graph transmitter used in ship-and-shore a nd with double-tuned aerial input wireless. Those of you who have good circuit. receivers may disagree with my rating 3: Multiple-stage tuned radio fre­ this spark transmitter as the second q uency amplifier with regeneration worst source of -interference, for to you and single-tuned aerial-input cir­ it is by far the most aggravating. But cuit. that is because you have already over­ 4: Multiple-stage tuned radio fre­ come trouble number one (cross-talk); quency amplifier without regenera­ our unfortunate friends whose receivers tion but with double-tuned aerial­ are so poorly selective that they cannot input circuit. listen comfortably to any but the nearest S: Simple regenerator with doy ble­ or loudest broadcasting station are very t uned aerial-input circuit. numerous, and we must give them first 6: M uItiple-stage tuned radio fre­ aid. q uency amplifier without regenera­ The fact is, however, that by impro\"­ t ion, with single-tuned aerial-input ing the selectiveness of your receivers circuit. you wilI greatly decrease the Morsecode 7: Simple regenerator with single­ dot-and-dash spark station interference tuned aerial-input circuit. that you now hear. YOli will never 8: M uItiple-stage unt uned radio eliminate it completely, however, for frequency amplifier with regenera­ spark transmitters will break through tion. and produce disturbances in the most 9: Non-regenerative audion detec­ highly selective broadcast receivers that tor with double-tuned aerial-input 60 CENTS can be built. The only real cure for spark circuit. John P. Buckley, scientist with station interference is to eliminate the 10: Crystal detector with double­ the U. S. Bureau of Standards, spark transmitters themselves. That tuned aerial-input circuit. completed this crystal detector and very thing is going on from day to day, 11: Non-regenerative audion de­ he claims they could be made and so you should alI be able to note a con­ tector with single-tuned aerial-input sold in quantities at sixty cents tinued improvement as progress is made. each. (Fotograms.) circuit. Since any increase in receiver selective­ 12: Crystal detector with single­ tion of the interference in your ness wilI aid in reducing both cross-talk tuned aerial-input circuit. locality, or it is so designed that its and spark interference, let us see what Remember that this list is arranged selective power is less than your can be done in this direction. First in the order of selectiveness, as it appeals particular type should have. we should consider the last or least to me. A different list would be required These two points state facts that selective receiver on the list I gave last to show the relative sensitiveness a nd a cannot be controverted, and it is just week, No. 12, the crystal detector with still different list to indicate the relative because of that that we can alI afford to single tuned aerial circuit. Lots of ease of adjustmen t. Still further, bear be optimistic about c utting out this cross­ people are using these outfits, and in in mind that to warrant its rating on this talk interference. If this trouble did not some locations they work very well if list any particular receiver must be well lie in your receiving sets it might be a they are properly put together. If you designed a nd well built; a poorly made hopeless Job to get rid of it; since it is have one, and if it is not performing to superheterodyne may be less selective necessarily the fault of your receiver, it your taste, you can probably improve than a good single-tuned simple regen era- can be cured right in your own home. it by putting a variable condenser in tor. Some of you may be inclined to doubt series with your aerial circuit, i. e., Cross-Talk the possibility of cutting out interferring between the lead-in of your aerial and Cross-talk between broadcasting sta­ stations which send on waves close in the binding post on the set to which the tions is without doubt breaking up more frequency to the one you want to hear. aerial was connected. Then use as much reception than a ny other single kind of People have said to me: "I paid $250 of the tuning coil as you can and do the interference. People who can at one for my radio set, and if it won't pick tuning on the variable condenser. A t ime hear music from some one station, up WCAF while WEAF is sending I still greater improvement can usually and hear it easily and clearly, find a little don't believe that anything will." The be made by connecting the crystal later than some other station begins to answer to this is that character is what detector and telephone side-circuit across dominate their receivers and that they makes a radio receiver good. Dollars (Continued on page 41.) RADIO AGE-"THE MAGAZINE OF THE HOUR" 23 Little Things That Help III II

SOLDERING HINTS Poor solderin~ will ruin the best of sets. Picture at the left shows how to make sure your iron is hot enou~h. Hold it five inches from your face and if you can feel the heat, you are ready. Be sure your iron is clean. It may be cleaned easily with a file, as shown in the picture at the ri~ht. (Kadel & Herbert.) Receiver Essentials This means the use of vacuum tubes, broadcasts could not be eliminated. Many radio fans are constructing their and radio frequency amplification or Even a few amateurs who work on 200 own receivers, some of which work well, regeneration. For a single tube set, meters were heard on this tuner, when and some which are tolerated merely regeneration is quite a desirable, almost tuned for the broadcasts. It is of no use because the builder has not the necessary necessary application. There are num­ to get loud signals, if you cannot pick funds to make a new one, says Beverly erous regenerative circuits to choose out the desired stations to the exclusion Dudley, member of the American Radio from, but for short wave reception a of the rest. The main objection a radio Relay League. For the construction of circuit in which regeneration takes place fan has to a two circuit tuner is the addi­ a receiver which is to work entirely by use of a tickler is most satisfactory. tional control. satisfactorily, a thorough knowledge of Regeneration is secured by means of the Tuners may be made in such a way radio principles is essential, but one may absorption method, which offers some as to afford the simplicity of the single get on well with a few pointers and his advantages. circuit tuner with the selectivi ty of the own common sense. Two Circuit Tuner loose coupled tuner, by making the The essentials of a good receiver are: For selectivity, a two circuit tuner primary of the circuit aperiodic. That is (1) Sensitivity, (2) Selectivity, (3) Ease seems to be the only one worthy of con­ to say that the primary is not tuned at of control, and (4) Moderate cost. To sideration. Tests made last winter all. This untuned primary consists combine all of these features is not as showed a single circuit tuner to bring in of from one to five turns of wire wound simple a matter as it may seem. the stations a trifle louder, but the over the secondary coil, or coupled to it. First of all, a receiver must be sensitive. tuning was so broad that local and loud These turns may be tapped or not.

SOLDERING THAT HOLDS The picture on the ri~ht shows how the point to which the connection is to be made should be cleaned with a piece of sandpaper. On the left picture shows how the iron is used after a little soldering flux has been applied to the contact point. The iron should not have too much solder on it and after the connection is soldered and cooled the connection should be wiped off with a little alcohol and a tooth brush. (Kadel & Herbert.) 24 RADIO AGE-"THE MAGAZINE OF THE HOUR" The Reinartz tuner uses a tapped but Amateur Records 9,563 Miles! untuned primary. This is a very satis­ Hartford, Conn.-By virtue of recent Hartford, Conn.-An amateur radio factory method of coupling the primary two-way amateur radio contacts estab­ message from France to the North Pole and secondary circuits. lished by Kenneth B. Warner, secretary has covered the farthest distance ever Ease of control is very essential, of the American Radio Relay League, traversed by an amateur relay, arriving especially to the radio amateur in his England comes to the forefront among safely in the ice-bound cabin of Captain t raffic work. One cannot tune a receiver nations of the world that can now com­ Donald B. MacMillan's schooner "Bow­ all evening merely to hear the bed-time municate across the Atlantic through doin" after a 9,565 miles journey. stories from Radioville, two miles away. radio stations operated by citizen ama­ The same night after Monsieur Leon Don't have seventeen t uniu& cc!'trols teur radio men. Nine complete messages Deloy at Nice, France, transmitted a on your receiver; three is plenty. A have been sent across the ocean on a wave message to the Arctic explorer, a repeti­ receiver may be--though they usually length of 100 meters between 1\1r. tion of the dots and dashes came in on are not-selective with but one tuning Warner operating station IMO here and the headphones of Donald Mix, radio control. Don't however, sacrifice effi­ J. A. Partridge owner of the English operator for MacMillan, 11 degrees from ciency for ease of control. amateur station 2KF situated in London. the pole and inside the aurora. As to the cost: buy inexpensive parts There is no question but what amateur if necessary; not cheap parts; there's a two-way transoceanic traffic has opened In order to reach Refuge Harbor, difference. The cost of many receivers up a new field of no less importance than Greenland, the message took a round could be kept down by taking off a lot the early successes, showing the possibili­ about course across the Atlantic to South of the trimmings; a receiver doesn't ties of amateur radio, and not a few of Manchester, Connecticut, where it was need voltmetel s or bezels mounted on its the old time hams, whose calls were received by John L. Reinartz, operating panel. famous in the old spark days, are bound­ amateur station IXAM. Reinartz gave Be sure to purchase a good variable ing back "on the air" to partake in the message by telephone to Boyd Phelps condenser. The one with the least parts international thrills. The tests are spoken of Hartford, who relayed it to 6XAD is all right. One cannot upon merely of as the dawn of a world amateur at Avalon, Catalina Island, off the coast examining a condenser tell its electrical relay. of California. Thence it was sent to efficiency. A variable condenser should Kenneth B. Warner, secretary of the Jack Barnsley of 9BP, Prince Rupert, be mechanically good. Hard rubber is League, estimated today that a total of British Columbia, who finished the relay. much better for insulation on a condenser sixty messages had been transmitted The distance covered by each relay t han porous, absorbent fiber. Get good across the Atlantic since the first two-way was about as follows: Nice to Hartford, mica insulated fixed condensers if you contact was made between amateur 3,500 miles; Hartford to Catalina Island, value the quality of the signals you stations IMO in Hartford and 8AB in 2,500 miles; Catalina to Prince Rupert, desire from your set. See that the fixed France the night of Nov. 27. The signals 1,305 miles, and Prince Rupert to Refuge condensers are well made and firmly pres­ of 8AB have been loud and scores of ama­ Harbor, 2,260 miles, making the greatest sed tight. A fixed condenser the capacity teurs are hurriedly bringing their receiver amateur relay mileage. of which varies is worse than nothing. down to the 100 meter wave length. In this remarkable record the French A radiogram received at League amateur used two foreign model tubes Headquarters stated that amateur with a 25 cycle plate supply and an input station, 9ZT, operated by Donald of about 400 watts. The receiving set used by Reinartz was home-made with Wallace, assistant manager of the his own type of circuit. Phelp's set was Dakota division, had been in two­ a Tuska 220 receiver. Mr. Mott of way contact with the French ama­ 6XAD used a Grebe CR 13 for receiving teur and messages had been ex­ and a quarter kilowatt tube for trans­ changed reliably. Deloy is believed mitting. Canadian 9BP used one 50 to have transmitted a total of watt tube for sending, while the North thirty-three messages. Pole receiver is a Zenith "3R."

:

HEARD ENGLAND Everett L. Battey's friends did not take his little one-tube set very seriously until recently, when he picked up three English stations. Everett's home is at Wollaston, Mass.'. He logged Bournemouth, Cardiff and London in one day. He uses a dry cell. RADIO AGE-"THE MAGAZINE OF THE HOUR" 25 The Superdyne Receiver N a recent talk, before the American Hundreds of separate experiments indi­ The dimensions and constants of the Radio Relay League in Chicago, Mr. cated that the successful operation of various coils and condensers are shown I C. D. Tuska, President of the C. D. the circuit depended to an extremely high in the accompanying table. Reception Tuska Company, gave interesting details degree on following dimensions carefully. on the detector has not 1 een particularly about the superdyne receiver-a new Not only does this apply to instruc­ successful probably due in part to the circuit developed by Robert S. Miner of tions about sizes of wire and dimensions capacity of the pkones on the unground­ the Tuska laboratories. but in addition care must be taken not ed circuit. VVhen operating with a small Mr. Miner, known to radio amateurs to parallel the grid and the plate wires of indoor antenna, the filaments should be as IRU, almost a year ago started to the radio frequency stage. These wires grounded and the antenna connected to work on a receiver that would give re­ must be kept at right angles and as far the grid of the first tube leaving out the sults which would surpass the regenera­ apart as possible. If the reverse feed­ antenna coupling turn. VVith this meth­ tive receiver and the many radio fre­ back coil is coupled too closely to the od, phones on the detector will probably quency outfits he had tested. grid coil the capacity between the grid be entirely satisfactory. In seeking for this new super circuit, and plate windings exceeds the negative The maximum results can be obtained he and his associates investigated all of magnetic feedback and the set will not after the operator has learned how to the latest circuits and every modification of regenerative, radio fre­ quency and other cir­ cuits about which they had information. In Mr. Miner's opinion, the only trouble with radio frequency is that it is not possible to get suffi­ cient amplification per stage, and he decided to locate the difficulties and then to overcome them. VVhen the superdyne circuit was being per­ fected it became evident that resonant circuits must be used, but as soon as this was done the tubes started to Xy oscillate and s poi led everything so that the investigators were · i n what might be called a "vicious circle." The method used to over­ come this difficulty was put in the conventional -AUDIO Armstrong feedback but AMPL.IFiE~ feed the energy back in the reverse direction or negatively. The circuit was given just enough feedback to offset the + positive capacity feed­ back of the tube. This - + stopped oscillation and 42. made it possible to SUPERDYNE secu re a bsol u te resona n ce Photograph of the assembled superdyne and diagram of wiring arrangement of this between the grid and the interesting receiver. As stated in the accompanying article the manufacturers]are plate circuits. Not only ready to assist fans in making this set if they desire instructions. was resonance secured, but the maximum impedance in the plate work. It is extremely important to carefully adjust the circuits but it is not circuit was used which means the biggest avoid this trouble so care must be taken possible to get these results until one has voltage impulse which it can be hoped to copy exactly the specifications outlined. had some experience in tuning fain t signals. to build up. The superdyne circuit is shown in the COIL DATA accompanying illustration. "RC" is the Micro­ resonant circuit of the grid. "VVC" is Coil Form henries the resonant circuit of the plate while O. D. Winding TURNS VVIRE TAPS "XY" is the reverse feedback which Secondary 4" 1 %" 42 No. 22 D.S.C. 0.20.42 273 stops oscillation. The detector is con­ Over Turns nected as shown. After it was found Sec. Spaced what the possibilities were with this cir­ Antenna %" 4 No. 22 D.S.C. 0.4 cuit, experiments were made to see if it Ball could be improved by changing the con­ Tickler Motor 18x2 -36 No. 22 D.S.C. 0.36 stants. All of the stages of increasing Plate capacity and decreasing inductance as Reactance 4" 1 %" 46 No. 22 D.S.C. 0.25.46 264 well as the reverse, were gone through. Condenser (Grid) Tuska Type 271 23 Plates Maximum Capacity .000482 Every sort of coupling and every con­ Condenser Plate Tuska Type 271 23 Plates Maximum Capacity .000482 ceivable manner of turns ratio was tried. VVave Length Range (Approx.) 176-358: 310-660. 26 RADIO AGE-"THE MAGAZINE OF THE HOUR"

The astonishing part about this outfit Numerous attempts have been made A few days ago a delegation of radio is that it operates without an antenna to simplify the adjustments of the re­ in te.rests representing the press clubs, and gives signals of sufficient intensity ceiver, such as using fixed reverse feed­ engIneers, broadcasters, and amateurs to be heard through the use of a loud­ back and gearing the two tuning conden­ called upon President Coolidge and the speaker. In Hartford, Connecticut, with­ sers together, but this method de­ Secretary of Commerce urging that a out the use of an antenna or loop or -ca­ creases the sensitiveness of the receiver. general conference be called in an effort pacity of any sort, other than the usual The closed circuits do not affect each oth­ to reduce interference from ships affect­ ground connection, broadcast has been er's wave lengths, but the feedback varies ing commercial amateur and general heard on a loud speaker from Chicago, with the wave length received. The broadcasting. The Secretary explained Davenport, Kansas City, and nearer reverse feedback has an appreciable effect that interference was decreasing due to stations. Havana, Cuba, has been ob­ on the grid circuit tuning. Fortunately, the vol un tary adoption of regulations tained without an outside aerial. however, the plate circuit remains ab­ laid down last year and that the Depart­ Desiring to compare this set with some solutely constant and may be calibrated ment was striving to remedy present of the sensitive sets on the market it was in terms of wave lengths. difficulties through revising the White recently taken to Washington and a \Vhile the Tuska company expects Bill which was passed by the House series of tests made. First, a constant to market complete superdyne sets, it last session. Any recommendations artificial source of power was set up. is willing to assist amateurs builcting which the committee desired to make in This was tuned on a regenerative re­ their own sets and will be glad to hear writing the Secretary said would be ceiver and the audibility measured of successful efforts. considered by the Department Officials around SO. \Vith the same power, the now working out the revisions to the same tubes, batteries, etc., the super­ existing radio laws established in 1912. dyne receiver showed an a udibility of The Proposed Radio Legislation Officials of the Government point out over 200. The same two outfits were Washington D. C.-There will be no that many difficult questions arise when tried under similar conditions with a regulatory legislatio" is attempted. Such broadcasting station as the source of general radio conference in Washington in the near future Secretary Hoover has questions as monopolistic control it is power. Here the regenerative receiver believed should be handled by courts showed audibility of about 60, while announced. The Commerce Depart­ ment is rapidly completing the details under existing laws and not incorporated corresponding conditions showed the of a tentative regulatory radio bill in radio legislation. superdyne receiver to have an audibility based on the old White Bill he explained. of 10,000, which was the end of the meter. The prohibition of operation by aliens He believes that this can best be done by if injected into radio legislation would The next test was of a more practical government officials without further tend to handicap American radio develop­ nature. Here the superdyne receiver conference. Practically all the sug­ ment commercially in foreign countries under actual receiving conditions was gestions offered by representatives in and could be regulated without being compared with the naval six-tube uni­ the several lines of radio work presented covered in a radio bill. versal radio frequency amplifier. The at last year's conference will be incorpo­ signals with the four-tube superdyne rated the Secretary indicated pointing The question of whether or not radio were probably three to four times louder out that conditions have not changed is a public utility is not essentially than with the six tubes of the navy am­ materially since last year except that necessary in a law which should be regula­ plifier. the number of transmitting stations has tory it is believed. The last experiment was the most increased. Some definite standards of operation astonishing of all. In this test the four­ When it is attempted to draw up and equipment espe~ially in the commer­ tube superdyne was compared with the legislative recomniendations or bills with cial fields must be included however, eight tubes on a super-heterodyne re­ a large body of diversified interests it it is asserted so that Secretaries of Com­ ceiver. Some of the signals on the super­ usually takes several months. Early merce will have some basis for their heterodyne surpassed this new circuit action on the new radio bill is necessary. decisions as to whether an existing while in other cases the superdyne ex­ station may continue operation in the ceeded the super-heterodyne. Taken all event a new company desires to enter the in all, and being very conservative, Mr. field or whether it must cease operating Tuska believed that the best that could to permit the opening of another station. be said for the super-heterodyne was that The amount of traffic might or might not the signals may have been slightly louder demand more than one station and using the eight tubes than they were efficiency would be questioned. on the superdyne with four tubes. Many phases of development indicate In operating this circuit it has been that broad latitude must be granted to found that it is highly desirable to adjust the Commerce Department but stand­ the plate circuit for the wave length ards of requirements and service in the to be received, then operate the reverse public interest should be made clear for feedback coil, which has been called a the future expansion it is believed. "stabilizer", and the grid circuit in ex­ actly the same manner as a regenerative Recently new interference problems receiver is operated. By carefully ad­ have arisen over which the Depart­ j usting the reverse feedback against the ment has no control under existing laws. positive capacity feedback astounding Complaints received report interference degrees of amplification can be gotten. from regenerative or re-radiating receiv­ I t has been figured that the voltage ing sets, violet ray machines, electrical amplification per stage probably runs in precipitating plants, bell-ringing mag­ netos on telephone lines, and leaking t he neighborhood of 100 times. One tube of radio frequency regeneration of insulation on power transmission lines. Government regulations should it is the old style rarely exceeds a voltage am­ believed give the Department power plification of eight or nine times. to prevent such interference. In order to simplify the operation the makers have omitted any tuned antenna After the presentation of the tentative HIGH LIFE circuit and simply used four turns of bill in the House and its assignment to wire which are closely coupled to the grid This experimental radio station the Merchant Marine and Fisheries Com­ was built in a treetop by two Oak­ circuit. This impulse excitation method mittee it is understood that public land, Calif. boys. ~hey say recep­ of tuning seems to be sufficiently se­ tion conditions are so good up hearings will be held at which time all lective, probably due to the selectivity there that a ,fellow can almost see interests may appear to present their of the two resonant circuits. the ether waves coming. (Keystone) suggestions and recommendations. RADIO AGE-"THE MAGAZINE OF THE HOUR" 27 An Inexpensive HOIllelllade Battery Charger By F. D. PEARNE

.",./*i~ I , ~---~ --~------+-~ -- I , ,,0- - -~----"oc------I- / / I I I NO. IS DRILL I { HOLES , 0_ -_o__ -L_+------L--ir------. \ I ' \ ~r----J \ ,, " ...... - - ~""---~'------, I , I I 1_ ," +;~B ~2.~

~I • . I I I I I I I , I I .I ,I I ~

"c// /J/'

FICURE I

The constructional and assembling details of th e Noden Valve Electrolytic Battery charger. This type of rectifier is designed for use in homes where the 110 volt house lighting current of the alternating type is available.

NE of the most essential require­ This outfit is known as t he "Noden thick. Bend one end over, one- half ments of a radio set is some valve" and will answer the purpose inch as shown at "A", Figure 1. Drill a O kind of a charging apparatus very well and in fact is really better than hole through the center of the part which which will keep the storage battery some of the rectifiers one may buy, for is turned over. This should be drilled charged at all times. This is compara­ tli.e reason that it rectifies both sides of with a No. 18 drill which is large enough tively easy where the electric lighting the alternating current wave, which to allow an 8-32 brass machine screw to circuit is of the direct current type, some of the standard outfits do not do. pass t hrough it. These plates should but unfortunately for the radio fan, most The mat erials required consist of four be ma de of soft a luminum for the reason lighting circuits use the alternating ordinary quart size mason jars, such as that hard aluminum will crack and break, current and before a battery can be­ are used for putting up p reserves; four if bent at a sharp angle. Next cut out charged with this cu rren t, some method pieces of sheet aluminum one-eighth of four pieces of sheet lead of the same of rectification must be used. Various an inch thick; four pieces of sheet lead size a nd shape as t he aluminum pieces, devices for this purpose are now on the of the same size and t hi ckness, four and drill holes of t he same size in the market, some of which are.r sold at wooden tops to cover the Jars, a few same place. reasonable prices, while others are really brass machine screws a nd nuts, and The wooden tops for the Jars should be expensive, and as the average radio fan about two a nd one-half pounds of phos­ turned out of hard wood. The flange usually has plenty of outlets:for his spare phate of ammonium. should be three inches in diameter and change, I am going to describe a rectifier First cut out four plates of good soft one-half inch thick a nd the smaller part which any amateur can build at an ex­ sheet aluminum, six inches long, two is two a nd three-sixteenths inches in pense of less than $3. inches wide and one-eighth of an inch diameter and one-quarter inch thick. 28 RADIO AGE-"THE MAGAZINE OF THE HOUR"

LAMPS CONNecTED IN PA/fALLf3l-

DI!?EC T Cl/8RENT ALTERNAnNG CURR£/VT + TE"RH/I"~L DIRECT CI/RFfENT TERMINAL /1L T£IfN~T/NG CVljR£/VT

FIGUR£2.

The wiring diagram of the jars and the method of connecting the lamps into the circuit to control the charging rate of the rectifier. Full details for the construction and operation of this unit appear herewith.

This small projection is to extend down the solution should be within one inch flowing out of the aluminum plate. It into the Jar and will just fit into the of the top when the plates are in the jars. cannot enter the cell below it, because neck of the quart-sized fruit jar. If any I t is a good plan to measure out enough of the aluminum plate, but will flow other kind of a jar is used, this size water to fill the jars three-quarters full out over the direct current terminal, should be changed to suit the case. and then add the phosphate of ammon­ through the battery and back on the If it is not convenient to turn these tops ium, until no more can be dissolved. negative direct current terminal, through out in a lathe they can be made of two In dissolving this chemical, it should the lower cell on the left side to the pieces cut out with a jig saw and fastened not be stirred with a metal spoon; use other side of the alternating current. together with screws, but these screws a piece of glass, so as to make sure that The next impulse is in the reverse must be so located that they do not no impurities get into the solution. direction and comes to the lower set interfere with the holes which are to Figure 2 is a diagram of the circuit, of cells. The aluminum plate in the be drilled, as shown at "B," Figure 1. which shows how the connections are left hand cell prevents the current Now mount one aluminum plate and one made. The aluminum plates are marked entering so it takes the path through lead plate on each of the tops as shown "A" and the lead plates are marked the right hand cell, coming out of the at "e," Figure 1. These plates are held "L" respectively. Lamps are connected direct current positive wire again, in place by 8-32 brass machine screws, in the circuit, which allow only a certain through the battery, back into the nega­ one and one-half inches long a nd fastened amount of current to pass from the tive direct current terminal, through with a nut on the other side. The nut alternating current wires to the rectifier. the upper left hand cell, to the other side should be turned up very tight so that Each lamp added in parallel as shown of the alternating current line. Thus it the plate is held rigidly in place. Another will allow more current to flow. The will be seen that the direct current ter­ nut on top of the first one serves as a direct current is taken off at the junction minal on the right side of the draw­ binding post to which the wires will be between the jars as shown. To recharge ing will always be positive, no matter connected later. the battery, connect the positive direct which way the alternating current flows. After all four units are complete c urrent terminal to the positive terminal This rectifier will give very good the part of the plates which was turned on the battery and the negative direct service and will put a good charge over, as well as the screw heads and current terminal to the negative terminal in the battery in twenty-four hours. the part of the wood which goes down into of the battery. A small hole should be drilled in the the neck of the jar should be coated with The action of this rectifier is based wooden tops to allow any gas to escape. melted wax, or paraffine to prevent any upon the principle that the current will As it wiII be necessary to "form" the gas or fumes from the solution cor­ not enter the solution through the plates before the rectifier will function roding the screws, thereby causing a aluminum plate. It will enter the solu­ properly, the two direct current posts poor joint. Next, make up the solu­ tion from the lead plate and flow out should be connected together for about tion with which the jars are to be partly through the aluminum, however. Let us ten hours while the alternating current filled, make a saturated solution (all the for example say that the circuit shown in is on, so that perfect rectification will water will dissolve) of distilled water and Figure 2 is connected to a source of alter­ take place when the battery is con­ phosphate of ammonium. It is necessary nating current supply. If the first nected in the circuit. After the plates that the distilled water be used as it will impulse comes in on the side of the cir­ are once formed, then the battery may not work if the water contains any im­ cuit in which the lamps are placed, be connected on the terminals at any time. purities. the current will not enter the aluminum A more efficient method is to use a toy Fill the jars with this solution to plate in the jar on the left side, but will transformer, connecting the primary within about one inch of the top, that is, enter the lead plate on the right side, (Continued on page 47) RADIO AGE-"THE MAGAZINE OF THE HOUR" 29 WJj;1: th~ Bro~dc~~ers ate Doing

Broadcast Records MERICAN broadcasting stations are A reaching out to such vast distances t hat it begins to appear that voice-radio rommunication with points up to 5,000 miles soon will be regarded as common­ place. The recent transatlantic tests called general attention to communica­ tion with English stations. But England had heard A merican broadcasters re- . peatedly before these tests and American receivers had frequently tuned in and picked up English stations. To WDAP, the Chicago Board of Trade station, belongs the credit of having entertained an English listener throughout an entire program of several hours. The operator who received this Chicago program was Thomas E. Ham­ blett, Windle Mount, Hard Lane, St. Helens, Lancaster, England. It may be difficult for Americans to understa nd how any message, much less a radio, program, could find a Britisher who was hidden behind such a complicated address as that, but Mr. Hamblett was found out not only by WDAP but by KDKA, Pittsburgh. On September 25, Mr. Hamblett was listening to KDKA at 1 :57 a. m. He wrote to KDKA saying he tuned out after twenty min utes be­ cause the market reports had driven him away. KDKA reached several other English listeners. Reception of WGY, Schenectady, was so successful in Queenstown, Ireland, during the transatlantic tests on the morning of November 27 that A. N. C. Horne was able to make a fifteen-second log covering the transmission from the opening announcement to the "sign-off." In his letter to the General E lectric Company station, Mr. Horne stated that reception was made on three valves -dectector and two low-frequency, with a n aerial twenty-five feet high and 250 feet long, inclosed by tall trees. H e explains that he has studied radio for the last ten years and that the highest degree of accuracy was aimed at in re­ 'GENE McDONALD cording his observations. He is owner of the Zenith-Ed~ewater Beach Hotel Station WJAZ, presi­ In his log Mr. Horne mentioned that dent of the Chica~o Radio Laboratories, president of the Zenith Radio the concluding number of the program, Corporation and president of the National Association of Broadcasters. "God Save the King," was "good." He equipped the MacMillan arctic ship with radio receiver and transmitter That is an odd thing about radio. The and talks to MacMillan every Wednesday ni~ht from the Chica~o station. patriotic hymn, "America," becomes On the ni~ht of Dec. 19 when talkin~ to MacMillan his voice was heard "God Save the King" in England. in the Samoan Islands, more than 7,300 miles distant. So far as known this is a world record. Mr. McDonald is a hunter, and a yachtsman. He is Mr. Horne sent records of WGY for leader of the ~reat fi~ht a~ainst the American Society of Composers, Authors November 22, 23, 24 and 25, indicating and Publishers, who tried to force broadcasters to pay lar~e fees for broad­ that he has little difficulty in picking up castin~ popular music. His real name is E. F. McDonald, Jr., and it is a the Schenectady station whenever it is name that is growing bi~~er and bi~ger in radio. (Walin~er.) RADIO AGE-"THE MAGAZINE OF THE HOUR"

l\Iedford Hillside, l\Iass., and Station 2-LO, London, England, it was a re­ markable coincidence that the first A merica n station to participate success­ fu ll y in this two-way communication was Amrad WGI, the world's oldest broadcasting station operating today, erected in 1915. It was a further sig­ nificant coincidence that Mr. H. J. Power, founder and active head of A mrad, who conducted the earl" broadcasting in 1915 a nd '16 a nd no\~ ' known as the "father of broadcasting," was at t he microphone when the success­ ful broadcast was made. According to t he sched ul e two-way communication was not to be tried until Saturday, December 1; but when 2-LO received the Ameri ca n station November 30, the British ama teurs could not re­ frain from calling back a n d were hea rd by ma ny A meri ca n li steners. Again on Saturday two-way co m­ munication was ma inta ined between Amrad WGI a nd 2-LO London and complete confirmation followed after an excha nge of cablegra ms, The achieve­ ment was a ll t he more remarkable as the A merica n station used onl y 1 SU watb in t he a ntenna.

,\VTAM's Record The new higil powered broa dcastin g station, WTATv!, in C levela nd, Ohio, was heard in E ngland before any special e Cforts were 111 ade in trans-Atlantic broadcasting, Mr. Ha mblett, fro m St. Helen's, abo w(ote that he heard the Willard Com­ pa ny's station quite clearly broadcast­ ing its pcog:am on Wednesday evening, November 2 1. Hepicked up WTAM at 3 :48 a. m., LOIl­ don time w!1i ch is five hours earlier than New York time, a nd heard the remainder of the Willard program with practically TIME SIGNALS no interference until the station signed Each day at noon C. J. Waldron. of Medusa, N. Y., gets the time signal from Station WGY, the General Electric station at Schenectady. Right off at 4:1 3 a. m" London time. I-Ii,; on the dot he pulls the r ope and rings t he villa ge church bell, ther eby afford­ letter stated that hi s reception of "Tlw i ng towns folk and farmers with t he means of setting clocks and wa tches. Lost Chord" sung by the Amphion i\lal(' It Qllartette was a lmost perfect. H a I' ~­ on the a ir. Accompanying the WGY Do ubtless the Samoan operator was blett's set is o ne of his own assembh' records were lo?s on reception of E nglish in terested in the messages that were using one stage of radio frequency a~(i b roadcasting st a tions, and it was ob­ goin g out to Dr. MacMillan, but, being detector tube. H is aeria l, accordin g servable that the \VGY transmission a good radio operator, he must have had to hi s letter consists of a si ngle wi :e faded less than tha t of the Engli sh sta­ quite a thrill when he realized that he antenna lU O fe el long and 33 feet hig h. t ions. was making a reception record that A number of other applause lette ''; Proba bly the most interesting long probably surpasses a ny other achieve­ have been received from fo , eign coun trie; distance record made recently by an ment t hus far recorded. within the t wo months this statioll, A merican brGad casting station was t hat F irst news of the rema rkable incident ope,ated by t \ e Willard Storage Batte _, of the Zenith-Edgewater Beach station reached the ofiice of the Zeni th Radio COlllpany of Clevela nd has been on ( l:e WJAZ. On Decembe r 19, or early in Corporation at 332 S. Michiga n av., when a ir. t he morning of December 20, Eugene the United States Nava l Radio Station F . Mc Donald, Jr. , president of the N a­ on t he Municipal Pier, C hicago, call ed t ional Associa tion of Broa dcasters a nd on the t elephone and reported they had Two Other Records owner of the fa mo us C hicago st a tion, a message from Sa moa reading as foll ows: A. F. Combs, of E nid, Okla" a nd was ta lking to Dona ld B. MacMill an, "YMG reports as follows: Please i\1. B. Norman, E ureka Cent er, Wi ,.;" ice-locked in his ship near the North inform Zeni th-Edgewater Hotel Radio reported what are believed to be long­ Pole. Un it ed St at es Naval radio oper­ Station that Chicago messages a nd music distance receiving records for 3-tl1l>(' ators reported three days later t hat Mr, to MacMill a n, North Pole, were received sets. McDonald's voice ha d been heard clearly by me at 7:45, Samoa time, December I e). Using receivers of the same type that in the Samoan Isla nds, more tha n 7,3 0U "ROBERTS." were designed a nd built by Dr. Fultoll miles away. Cutting a nd Bowden Washington, Away down the re in the So uth Seas, AMRAD'S RECORD Minneapolis, iVIinn., Combs, at Enid, twelve degrees south of equator, the \Vhe n two-wa y communi cation by li stened to three numbers-vocal, or­ operator of a radio receiving set was voice was establi shed for the first ti me chestra and piano-broadcast by 2-LO, " li st ening in " for a ny bits tha t he might in the history of radio, Friday evening, London, Eng., a nd Norma n picked lip pick up from the world abroad. November 30, between Amrad WGI, a station at Glasgow, Scotland. RADIO AGE-"THE MAGAZINE OF THE HOUR" 31

Combs verified his feat through 2-LO's enrich the a ppearance of the room which secured to assure maximum musical New York office and Dick and Adolph is furnished with carved walnut furniture quality. "Valls and ceiling were covered Danielson, of St. Croix Falls, Wis., who of the 18th century period. Adjoining with special sound-proofing material were listening in with Norman. t he reception room is the ladies' rest and then the studio was turned over to room. On the first floor is also a large the artist. The decorator has hidden room for motor generator sets and stor- a ll evidences of the true purpose of the SUNSET STATION age batteries. room. GO, the Sunset Station, has come On the second floor are two studios Adjoining the st'.dios is a "silent" K on the air with the new year. On similarly appointed, one large enough room in which the performer is ushered the western edge of the United States, to accommodate a chorus or symphony to remain until summoned to the studio. at Oakland, California, two steel towers orchestra; the other, a smaller room, On the second floor, but unseen by have arisen and from the antenna, on for the broadcasting of solos and ad- the performers, is the control room. January 8, the new voice vibrated on the dresses. The use of the two studios a lso Here with headphones at ear, operators air. KGO is the second rF======;:======~;::=;===;:===il listen critically to every link in a chain of three word a nd note compen- super-broadcasting sta- sating for differences in tions planned by the 0 tone and volume among General Electric Com- the artists and flashing pany. The first is WGY, warning through silent at Schenectady, N. Y., electric signals to the now completing two studio manager, when it years of popular broad- is necessary to alter the casting, and the third position of the singer or will be erected at Den- instrumentalist in respect ver, Colorado. to the microphone. The For the first time a n control room has three entire building has been stages of speech amplifi- constructed to house a cation consisting of two great station and its 5-watt tubes and four equipment to be llsed I T EO SO-watt tubes. A fourth exclusively for popular stage of speech ampli- broadcasting. This indi- fication is installed in the cates that the General S power house. Electric Company has KGO is operated at faith in the permanence 1000 wa t t s, but the' of broadcasting. /' equipment; is designed in The Oakland station ,," + excess of that power for in its studio, control- A ,,' purposes of conducting room and power station p. C 1= /' tests'. In operating' high- embodies the latest de- ~c{' I powered equipment be- velopments in the art. .(',v C low normal rating in Its power and antenna 00 broadcasting, tubes and systems, a thousand feet '\~ rectifiers are not subject away from the studio, to occasional overloads building, include all the H------;,,~- ______lL~.!'I<.?~______a nd, as a result, superior mechanical and techni- ",-' quality and greater re- cal refinements that have ,0 C 12 liability of transmission marked the new achieve- ,'A is obtained. ments in broadcasting. -. ,,' '" The power house and By means of KGO the ~/ antenna system are 1000 listener in Maine be- SAMOA feet fro m the studio comes an air neighbor of p IS. building. Nine motor- the folks in California. C> "';. generator se t sin the The Pacific Coast sta- power house supply fila- tion is located on East 7,300 MILES ment a nd plate current 14th Street, Oakland. Among all the recent distance records recently made by for the oscillator, modu- It is a two story brick radiophone broadcasting stations by far the most startling is that lator and kenotron recti- building. On the first of WJAZ, the Zenith Edgewater Beach Station, Chicago. E. F. fier tubes. floor, near the entrance, McDonald, Jr., was talking to Dr. Donald B. MacMillan, ice- There are six tubes in is the office of the studio bound near the North Pole and his message was heard by a radio the kenotron rectifier manager who pla ns pro- operator in the Samoan Islands. The South Sea operator's achiev- assembly, one met a I ement was reported t hree days later by the U. S. Naval radio gra ms, selects artists, station at Chicago, having been relayed back by naval operators. plate oscillator tube, and a nd co-ordinates the du- one metal plate modu- ties of the office a nd broadcasting staff. makes continuous broadcasting possible. lator. Every part of the equipment in Close at ha nd is the correspondence The announcer has but to step from one the power house and in the control room room where the business of the station room to the other at the conclusion of a is in duplicate, assuring uninterrupted is carried on. H ere a staff of assistants number and find the n ext performer service. If one outfit or part of an outfit attends to the details of program-making, waiting for the word to begin. breaks down during t he operation period interviews callers, keep logs of every It is in the main studio t hat the art a nother outfit will be ready to be brought performance and a nswers and files the of the decorator reaches its fullest ex- into the circuit. letters received from the li steners. pression but before the artist began his The antenna is of the multiple-tuned On this floor there is an attractive picture, working with tapestry, carpets type and is strung between two steel reception room covered, as is the en- a nd draperies, the engineer had lined towers, each 150 feet high a nd 250 feet t rance hall and stairway, with a rich, the wall s with a mesh of insulated wires apart. Beneath the antenna is the heavy piled carpet of a beaver ta~pe connectiI?g microphones with control counterpoise consisting of a network color. The woodwork is painted a soft apparatus in an adjoining room. After of wires, fourteen feet above the ground, antique ivory a nd is glazed a Van Dyke the wiring was completed exhaustive covering an area of 150 by 300 feet. In brown. The walls are covered with a experiments were made to determine addition to the power house which is two tone gray and blue figured tapestry. the reverberating qualities that the one story high, 71x32 feet, there is a Draperies of blue and taupe damask proper amount of "damping" might be small building for the tuning apparatu~ 32 RADIO AGE-liTHE MAGAZINE OF THE HOUR"

and the end of the multiple-tuned station, WGY at Schenectady and the transmitter of the portable set outside. antenna. proposed Denver station. J. A. Cran­ The wavelength is too low to interfere KGO, the Pacific Coast station of ston, Pacific coast manager for the G-E, with the usual receiving sets or broad­ the General Electric will not be de­ has direct supervision of KGO. casting stations and it is also so low that pendent upon its own studios alone for there can be no interruption from spark programs. Located as it is near the Portable Station transmitters. great cities of the Pacific Coast, it has By means of a sensitive receiving set a rich field from which to select music SHORT wave radio transmitting set located near WGY, the electrical vibra­ a nd eloquence. By means of broadcast­ A which may be transported to the scene tions into which speech or music has been ing pick-up circuits, the Sunset Station of church services, concerts, dramatic converted are picked up, amplified and will be equipped to broadcast the speeches performances or lectures, as easily as a then conveyed to the main transmitting of important public gatherings, the ad­ motion picture cameraman is sent on equipment of \VGY, from which the dresses of prominent citizens, sermons news-weekly assignments, has been intro­ program is put on the air on the licensed by pastors of leading churches, concerts, duced as part of the broadcasting equip­ wavelength of the station, 380 meters. theatre productions a nd occasionally, ment of \VGY, the Schenectady station Prior to the introduction of the radio important athletic events like baseball of the General Electric Company. relay it was customary for WGY to con­ or football games. This set is not used to broadcast nect church and radio station by wires. The Oakland station will be on the directly to the listener, but is a radio Wire installations required considerable air every Tuesday, Thursday and Satur­ relay which conveys the program to the preparatory work and because of the day nights carrying instruction and enter­ broadcasting station. This first radio time involved in making the necessary tainment to the great audience of the transmission can not be tuned in on the installations some programs that might Pacific Coast and, when atmospheric average radio receiving set. have proved instructive and enjoyable conditions are favorable, to the fans The portable transmitting set is had to be omitted. The small trans­ throughout the country. The wave­ conveyed to the hall or church from mitting set is mounted in a covered length of KGO is 312 meters. which it is desired to broadcast an enter­ truck and may be taken to hall, theatre or Martin P. Rice, director of broad­ tainment or sermon. \Vire connection is church, where in a short time the installa­ casting for the General Electric Company established between microphone or pick­ tion will be complete and ready for has charge of KGO, the new Oakland up within the hall or church a nd the service. Re-broadcasting does not affect the quality of music or speech. WGY has made frequent use of the radio relay methods and the listeners were at no time aware that a radio transmitting set working on a low wavelength had supplanted the wire link in the system. There is another and even more im­ portant use for the small transmitting set in radio relay and this use suggests a particularly interesting development for radio in the future. In the relay now in common use at WGY, the small station is used to feed into the larger transmitting set through the introduction of a receiving set between the radio links. It is possible that the future will see many of these small transmitting sets scattered about the country and used to re-radiate on lower wavelengths, concerts received on a sensitive receiver from anyone of a half dozen main stations, for the benefit of li steners with crystal sets or short dis­ tance receivers. For example, such a receiving set might pick up the best of the WGY program from Schenectady and then a special feature from \VJZ or other station and by the use of the transmitter re-radiate to the country side within a limited dis­ tance of the station. This would give the man with the small receiving set the advantage of listening to a selected program, the best of the main stations. I n this manner he would be able to get programs, and to get music that would not otherwise he available to him on his set. Many of the distant stations can be tuned in at will when atmospheric conditions are right but there are nights a nd days when the average set has difficulty in getting dis­ tance. The small re-radiating or relay station practically assures- success to all the fans within a hundred miles, at least.

RIPPING! Radio in Jail That's what the Duke of Sutherland thinks about radio. He has been investigating American aviation and the picture shows him talking to "Four walls do not a prison make­ American BeL's from Station WJZ, New York. Swagger microphone and nor iron bars a cage." The line from the topping haircut, we say. (Kadel & Herbert.) old poem has been applied to many situa- RADIO AGE-"THE MAGAZINE OF THE HOUR" 33

RADIO PENETRATES STEEL TUNNEL CASING G. Y. Allen, radio engineer of the Westinghouse Manufacturing an~ Electric. C?mpany is shown tes~ing recep­ tion conditions in the New York-New Jersey vehicle tunnel. Broadcastmg was distinctly heard from Philadelphia, Pittsburgh and other cities. The radio waves passed through 500 miles of air, 70 feet of water, 30 feet of mud and through the heavy steel casing of the tunnel. (Photonews.) tions since it was written. Now comes receiver and that his companions in near­ "Mike" Tests Nerves its application to radio. by cells listen in to concerts after the Broadcasting has developed a new test WTAM, the broadcasting station of lights are out. for the nerves, according to several radio the Willard Storage Battery Company, "The radio helps us to pass the long broadcast managers. Cleveland, Ohio, received Christmas nights as well as to keep up our courage "Stage fright," "movie nerves" and greetings from three prisoners in ac­ and to appreciate what freedom means "buck fever" are a ll well known to the knowledgment of radio programs re­ once we get it again," he writes. public, but the little metal microphone, ceived by them. Two of these were pris­ "BIG BROTHER CLUB" "the door to Radio land," has sent terror oners of sickness. The third is actually to the hearts of many seasoned enter­ confined in a state prison. Boy and girl radio fans all over the tainers who have performed before Mrs. Harold N. Pember, of 14 Goshen East are becoming greatly interested packed houses without a tremor. Street, Hartford, Conn., sent a disin­ in the newest Amrad broadcasting Appearing for the first t ime before the fected letter, saying shc was quarantined feature conducted at WGI, Medford "Mike" the artists, al most without ex­ with her daughter who has scarlet fever. Hillside, under the name of "The Big ception, ask: "How many people will "You will never realize what a boon the Brother Club." Over 200 boys and hear this?" What tone of voice shall I radio has been on these long, lonely girls are enrolled as active members at use? Do you think I have a good voice evenings," she wrote in appreciation of the present time. for this work?" and many other ques­ WT AM programs. "The Big Brother Club" is not unlike tions indicating nervousness. Robert H. Bean, of Manitowoc, Wis., the Boy Scouts and Camp Fire Girls Having performed before "lV'like," sent the season's greetings, saying there in purpose and principle. It appeals to who is cold and unresponsive, the artist is no station in the United States he en­ boys and girls from 9 to 12 years old, waits impatiently for letters from the joys more than WT AM. Bean was a and, accordin g to the by-laws, "any invisible fans, whose faces he coul d not marine engineer on the Great Lakes be­ boy or girl owning or li stening-in regularly read, to learn whether or not his act fore an accident left him paralyzed. on a ny receiving set is eli gible." The "went over." Unless he receives letters Cleveland, the home of WT AM, is fa­ dues are one letter each week to "Big of applause his fever is likely to rise miliar ground, he says, and the concerts Brother." Meetings held nightly from until it becomes dangerolls. bring back the good times he has had in 6 to 6:15. Each new member is issued port there. a Certificate of Membership Card duly The third letter was from Ernest inscribed. Graham, prisoner in Virginia state peni­ It is expected that Big Brother Clubs tentiary, Richmond. will be established at other broadcasting Graham is allowed a radio receiving set stations in the near future. Address in his cell through the kindness of the all communications to C. R. Emery, prison superintendent. He says there are care of Amrad, WGI, Medford Hillside, twenty-four head phones attached to his Mass. 34 RiDIO AGE-"THE MAGAZINE OF THE HOUR"

to say that fa ns could have a copy of his circuit b y writing. In a later communi­ DIAL TWI STERS cation, M r. Laudell says: Names Addr esses Circuit " I t hrow u p m y ha nds-I can' t possi­ Norris S u mmers______Pee Wee Valley, Ky. ______.. ____ .. __ . ____ . ______$in~l e Circuit bly a nswer t he mass of inquiries that Richar d Jones______Milwaukee, Wis. ______. __ S in ~l e Circuit Earle Kidney______Ste rli n~, Ill. ______. ____ . ______$ in~l e Circuit come in. \ Vhile I a m writing this, I Harvey J . Duneka______2641 N. Central Ave., Phoenix, Ariz. ______.. _.. ___ Ultra Audion have a splitting headache from writing a nd reading letters in a nswer t o inquiries ~~~~~t~~i~~h~L. ______::::::: ~~i: ~: g:~:~ ~~::= :::::::::::::::::::::-::':::::::::::::::::::::::: ~:~ : : : g~~~:~ Both the above TWISTERS live in I n dia n a polis. Ind. received in response t o the offer I made. :!.l~~n~:nri'e~t~-osi-~~_ ::------::-: __ ~o~~~~~: ~:~twi n~s~;:,~n~::-Ca-~-.-___:::::::::::: ::: ::::::: ~1ie~~~~~~ I have n ow received 500 letters." Alex Mack ______... ______1020 Cherr y St., Norristown, Pa. ______Hop wood Circuit \Ve wrote M r. La udell for his circuit , a nd in reply he says: RA DIO AGE, Gentlemen: NeE upon a time there was an feat, will p ut your na me in t he list of You will find enclosed the circuit on Editor who wanted to give the DIAL TWIST ERS, and if space permits which I compiled t he list of stations pub­ O fans a chance to compare records publish your letter. li shed in your December, 1923, issue. in his radio magazine and let the readers Everybody has a n even ch a nce-no Upon inspection y ou will see that the know that he wanted li sts- matter if you have a ten-t ube super ­ circuit needs no co mment or special That's us. We like to give the fans heterodyne or a on e-tube fi rst t ube cir­ parts other tha n a common v a riocoupler what they want, and we try to please cuit. \Ve will carefully consider t he m which must be rewound to suit t he cir­ -t hem in every way possib le both, and if t he one list a nd letter shows cuit given. I am enclosing detailed infor­ Some time ago, we requested through more meritorious work, we will pu b li s_h ma tion regarding t he wind ing of the coils t his department that fans send in their that one. on t his coupler, and t rust tha t fa ns may lists of stations heard, and we got j ust 'What say fans! How many of you are find as good results await ing t hem as I what we deserved. No restrictions were going to be classed as d ial twisters next have received. published as to the length of the li sts, month? Very truly yours, and by looking over some of those sub­ THE PICKUPS EDITOR. E . L. LAU DELL. mitted, you'd think you got a hold of the We a re p rinting in F igure 1, a copy of call book for all the stations of the world. Ou r December 1923 issu e contained t he circuit which Mr. La udell contends is We find that it is an impossible thing a n interesting account of reception superior to ma n y ot hers. The primary of for us to determine the record holder for record made by Mr. E. L. Laudell, o f t he coupler has eighty turns of No. 28 t he month, and we cannot find any real Shelbyville, Illinois on a ci rc uit of his D C C wire, with taps take n off as fol­ restrictions to impose on these fans who own design. Mr. Lauclell instructed us lows : laugh at distance as far as radio listening is concerned. It's this way. Willie Jones writes in telling us that he has heard station XYZ transmi tting on sixteen meters, which is located four thousand miles from his house. Mr. Smith tells us that AOJUStABLE his set using a 23-tube u ltra-super­ heterodyne has heard all in all six hun­ dred stations from the Alps to Omaha. The point is-whose should be con­ sidered a record? I I We'll handle it this way. In order to , I give all the fellows a chance at this, we're going to establish the order of DIAL __2.'.! ___ _ TWISTERS. We'll publish the lists of ---~-- I " ,OOOS' t hose fellows who do real long distance work from a standpoint of location, type I "- I of set, and operating conditions. \Vhe n I you write enclose your list neatly com­ piled, with data on the type of receiver, and any other information that you think would be of value in determining whether you are entitled to the name of DIAL TWISTER. + The Pickups editor will read them over carefully, note the lists, and condi­ tions under which the work was done, and FIGURF. 1 if he thinks it contains something of a RADIO AGE-"THE MAGAZINE OF THE HOUR" 35 Make Your Receiving Set Selective Tap the first ten turns every turn, and then wind seventy turns of the wire bringing out loops for taps every tenth For Transmission turn. This makes the coil have seven taps of ten turns each and ten turns of 1 or Reception! tap each. The secondary is rewound with the same size wire and had 64 "FRESHMAN SELECTIVE" turns. The secondary in the circuit really is not 11 secondary but is used as a tickler. MERCURY VARIABLE CONDENSER The remainder of the circuit is standard with respect to parts, and the diagram shows how the connections are made. Mr. Laudell would be pleased to hear from fans who construct this circuit.

On page 4 of the August issue, we print­ ed a short item regarding reception of signals on short antennas by various fans, a nd Mr. B. O. Borgeson found that a score of people took the trouble to look up his address, a nd write him concerning The Benson Melody Filter eliminates his experiments. annoying interferences It is thf in­ ductively coupled type with a high Mr. Norris, Summers, Pinvee Valley, grade .001 mfd. variable condenser. Ad Ky., writes us: mounted in a beautiful leather covered RADIO AGE, cabinet with an engraved bakelite panel. Gentlemen: Price $8.75 After reading Mr. Foltz's letter in the BENSON MELODY CO. January number last night I decided to 2125 No. Haloted CHICAGO, ILL. take down the stations heard before Sead 25c ror a Beus .. Melody lIadio "Trouble Findiuln Chari turning in. So as a result I am sending my list It has been conceded by the whiCh contains fifty stations all of which Foremost Radio Engineers that were plain and clear. a Variable Condenser with I do not claim this to be a record as I Mercury plates is the most Here's your opportunity. Radio needs can easily do as well any good night. efficient for fine adjustment and you. Win success in this fascinating field. My set is a single tube type, using a 'Trained men in demand at highest salaries. selective tuning. Our engineers, Learn at home, in your spare time. U V 199, in the much ridiculed single circuit. after exhaustive experiments Be a Radio Expert Very truly yours, and research work, have de­ I will train you Quickly and easily, to design, velop~d a Variable Condenser constroct, instali, operate, repair. maintain, and NORRIS SUMMERS. :~ ~~i:~: eC;:::8~~';J'Y~~~~~~~:.YLee;~~t~~: Mr. Summers' list is' as follows: with Mercury plates separated $1,800 to $10,000 a Year CKAC, Montreal, Can.; WJAR, Provi­ by heavy Mica dielectric. It 1S dence, R. I.; WOAW, Omaha, Neb.; the ONLY VARIABLE CON­ F R E E ~o:~f1iu~,:o~tC~~8ra~~~o~~8~~~ WCAE, Pittsburgh, Pa.; WWJ, Detroit, Writefor"Radio Fac~s" free. Engineer Mohaupt. DENSER the plates of which #.mericl'ln Electrical Association Mich.; WOR, Newark _ N. J.; WHAM, actually vary in area-AN EN­ Dl1J)t. 22·A 4513~avenswood Ave., ChiCi!80 Rochester, N. Y.; WHAS, Louisville, Ky.; WDAP, Chicago, Ill.; WGY, GINEERING FEAT NEVER Schenectady, N. Y.; WDAF, Kansas ACCOMPLISHED BEFORE, CLASSIFIED ADVERTISEMENTS City, Mo.; WJAX, Cleveland, Ohio; KFKQ, Conway, Ark.; WCX, Detroit, No Leakage !:d ~t!:r .:::: Cr,,:::::=:n, ~c~dwJ:i ..:=~ •• oae word. Copy muot be recelyed by the 15th of Mich.; WTAS, Elgin, Ill.; WSAI, Cin­ Absolutely quiet IDOnth for oucceedin8" month'. looua. cinnati, Ohio; WBZ, Springfield, Mass.; No plate vibration HELP WANTED WSB, Atlanta, Ga.; WMC, Memphis, Will stand 5000 volts Tenn.; KSD, St. Louis, Mo.; KYW, U. S. Government Positions, $100 to $250 month. Compact and attractive Chicago. Ill.; WIP, Philadelphia, Pa.; 3:~I-Cai::'i:::~poB~:ffi~~CI!k~~i~c~~~ T;'~Ak~dit~~? Plates cannot collect dirt Steady work. No strikes-no leyoff's, Pleasant, in­ KDKA, Pittsburgh, Pa.; WEAF, New teresting. Short hours. Paid vecetion. Influence Cannot become short circuited. unnecessery. Schedule exeminetion places-free. York, N. Y.; WFAA, Dallas, Texas; Men-women, 18 up. Write immedietely. Franklin Inatitute, Dept. G, 114, Rochester, N. Y. WJAD, Waco, Texas; WNAC, Boston, Mass.; WEAN, Providence, R. I.; . 0003 m. f . (equivalent to 17 pla te) FREE HOOKUP WCAP, Washington, D. c.; WMAK, .0005 m. f. (equivalent to 23 pla te) Sbty-thouoand mlleo on Home-mede Receiver. Twen­ ty-ob hundred mile renge. Hundred-otatlon log and Lockport, N. Y.; WCAS, Minneapolis, .001 m. f. (equivalent to 43 pla te) Hookup free. Spencer Roach, 2905 Columbia Ayenue, Phlladelphlo, Pa. Minn.; WOAN, Lawrenceburg, Tenn.; WLAP, Louisville, Ky.; WHN, New BOOKS ALL $5 York, N. Y.; WOI, Ames, Iowa; WHB, TYPES Kansas City, Mo.; WJZ, New York, N. Y.; WBAP, Fort Worth, Texas; At your dealer, otherwise send purchase KFMQ, Fayetteville, Ark.; KFEX, Min­ price and you will be supplied postpaid, Write for FREE diagrams of Neutrodyne, neapolis, Minn.; KGO, Oakland, Calif.; Tri-Flex and other good circuits. RADIO CALL CARDS prInted TO ORDER. Red cell, KHJ, Los Angeles, Calif.; WJAZ, Chica­ black printing. 100, $1.75; 200, $2.75, prepeid. Color go, Ill.; WLW, Cincinnati, Ohio; WBAK, changes 35c extre. Government postels Ic extra eech cerd. LETTERHEADS 8 1-2x5 1-2 AND ENVELOPES, Harrisburg, Pa.; KPO, San Francisco, 100 EACH, $2.25: 200 EACH, $3.25. ARRL emblem used on cards or atationery if requested. Send TODAY. Calif. ; KFI, Los Angeles, Calif. ; WJAN, Department 62C, RadiO Printers, Mendote, Illinois. Peoria, Ill.; KFDL, Denver, Colo.; RADIO ODDS AND ENDS KGW, Portland, Oregon. lhas.l='res~man 10. Inc. No. 14 squere tinned bus wire-- 2 ft. lengths-64 feet wumcl Condenser ~"dlLCl'l for $1.00. $1.20 set of 8 lettered binding posto-60c. Speghettl-3 ft. lengths, red, yellow, green or bleck- Wot say, fans? Looks like the single 106 SEVENTH AVE. NEW YORK 7 lengths-21 ft.-$1.00. 50 essorted bress screws, nuts, waJIhers, lugs, etc.-SOc. All four Items prepaid circuits are coming to the fron t this return mell-$3.00. Redio list for stemp-none free. Kledeg Redio Leboretorics, Kent, OhiO. issue. We remell1ucr way uack when a " 36 RADIO AGE-"THE MAGAZINE OF THE HOUR" Pickups By Readers (Continued) fellow could look with pride at a record WOC, Davenport; WSB, Atlanta; WHB, That's a little boost for the users of of thirty miles or so with an electrolytic Kansas City; WWJ, Detroit News; ultra-Audion receivers and here's another detector-and now WTAS, Elgin; WSAI, Cincinnati; WRM, one: Read this one and weep! Urbana, III.; WEAF, New York City; RADIO AGE, RADIO AGE, WF AA, Dallas; WCAP, Washington, Gentlemen: Gentlemen: D. c.; WBAH, Minneapolis; KSD, As a radio amateur of long standing, I have read with interest letters in the St. Louis; KFKX, Hastings, N ebr.; but who has only lately become ac­ Pickups Dept. Now I'm out with my W NAV, Knoxville, Tenn.; Washington, quainted with RADIO AGE, permit me record, which I believe takes honors Pa.; KHJ, Los Angeles, Calif.; CKY, to felicitate you upon the practical wis­ from Mr. Foltz in the January number, Winnipeg, Canada; WJAZ, Chicago dom and sound judgment which its a nd also Mr. \Vright of Madison, \Vis., (Edg. Beach Hotel). editorial contents show. in the same issue. I have a single tube KHJ, KFI and CFCA and other Pa­ I read four different radio periodicals. single circuit receiver which I built cific stations all come in with surprising Each is good of its kind. Yours is myself and wouldn't trade it for any set volume and clearness. I can pick them quite the most useful to the everyday regardless of make or price. I have up when they are on the air at will. semi-dumbbell like myself, who wouldn't heard 151 stations in thirty-two states. Last Saturday evening (January 12) I know a heterodyne if it bit him on the The following are stations over 1000 heard about twenty-three stations and ear, but who does admire for to fool away miles distance: KPO, KFDB, KFI, not trying for records either. In the life building ntew circuits for his ownself. KWH, KHJ, PWX, CHBC, CFCN, course of the evening I had heard among Incidentially, even for those of a high­ WCAR, WCAK, WBAP, WPA, WFAA, others PWX, KGO, KHJ, KFI, KG W, er order of mentality than mine, I ob­ KFDF, KFAF, WWL, WAAP, WFY, CKCE, WHN and KPO. Pretty good serve a definite authority and precision WEAH, WBL, WKY, KFKB. jaunt, don't you think? Local stations in your published utterances which are A total of twenty-two stations with a such as Chicago and Kansas City come a pleasing contrast to the wide scope 32,650 mileage. If any other reader can in so loud that you can hear them 15 to many radio editors seem called upon to show twenty-two stations totaling that 20 feet from the phones. allow themselves. much with a single tube set, I would like Let me hear from some other single I specially congratulate your Mr. t o see it. I have heard as high as thirty­ circuit fans as to a record of stations Felix Anderson upon the clarity and t hree stations in a single evening between heard as consistently as that! accuracy of his drawing. Nothing more seven t hirty and eleven thirty. In three Very truly yours, helpful to me has come my way since nights I heard 51 different stations and EARLE KIDNEY. first I dealt with radio. did not count any station twice either. Sterling, Ill. I built the ultra-audion one tube cir­ Here's another: I have listened to cuit, described in your October number, KFI at Los Angeles four consecutive The copy boy watching over our from one of Anderson's drawings; and nights for from 30 to 45 minutes each shoulder as we type this remarked with a it is a marvel of compactness and effici­ time. Perhaps I could have listened whistle: "Whew! I'm gonna' go home encv. It outclasses a sixty-dollar lo nger only the lure for more distant t'nite an make me one of them tuners. "bo'ughten" set in distance and selectiv­ stations would not permit me. Wotta list, wotta list." We're almost ity, as well as in volume and freedom lowe all my success to a good tube, ready to follow the copy boy's example from distortion; while, as you can guess, a nd careful tuning. and junk that Rolls-Royce receiver of it didn't cost anything like that money! Yours for RADIO AGE, and single ours after reading that list. Fine work, May I suggest the addition of a vernier circuits, Mr. Kidney. condenser similar to the Chelten Midget, RICHARD JONES. which I am using in this circuit of yours When you read over that, you'll Dec. 31, 1923. and which I find a great help in cutting probably say U mmm! Pretty good, RADIO AGE, out in terference. pretty good, but we'll say-GOOD!!! Dear Sirs: The first night I hooked up the set HUH! THAT'S PERFECT! We think I got QSADX on the following: CHYC; it's so good that we're . putting Mr. I have been greatly interested by what RADIO AGE has to say on the Ultra WIP; WDAR; WSAI; WEAF; WOC; J ones' name on the Dial Twisters list. \VOO; and the rarely-heard (by me, at Congratulations, Mr. Jones. You're Audion Circuit. For the past eight or ten years I have been trying the various least) WOQ. These, in the order named, one of the highest Dial Twisters for the within an hour and a half, tuning through month. hook-ups as fast as they have been foisted upon the unsuspecting experi­ local broadcast from WWAP on 225 menter, but even the ones with lots and meters. Not so dusty, what? And here's another single circuit bug: Good luck to you! RADIO AGE, lots of dials and switches can't beat the Ultra Audion for volume or selectivity. Yours sincerely, Gentlemen: D. G. WYLIE. I have been reading some of the fine At present I have only the 23 plate distance records made by fans, and want variable condenser, and a rheostat, on the panel, with 75 turns of No. 24 wire on a to contribute my list. I am using a And seeing that we are featuring single circuit t uner, a nd for selectivity Quaker Oats box in the rear as a fixed single circuit sets this month, we giv(' inductance-no taps. I find this far a nd ease of control together with its you a shot at this one compiled by two superior to the other methods of winding great volume I don't believe it can be youngsters in the radio game: coils; the variable condenser covers beat. I can't just remember the date but RADIO AGE, meters from 238 to 526 with a 75 foot a week or two before Christmas I picked Gentlemen: aerial, and tuning is very sharp. Using up the fo llowing stations from seven in the We have read several copies of your evening to ten: KYW, Chicago (West­ one tube I regularly hear Chicago from magazine. We have taken special in­ inghouse Elec.): WOA W, Omaha; WLAG, Phoenix, Ariz.,' with KFAD, a mile terest in the "pickups." We are the Minneapolis; KDKA, East Pittsburgh; away, making all the noise he can. proud jowners of a single circuit regen­ In thanking you in advance, I would WGY, Schenectady; WL W, Cincinnati; erative one-bulb set. We have a record WDAP, Chicago (Drake Hotel); WJAX like to add that RADIO AGE is exactly which was made on the 11th of January, Cleveland; WJY, New York City; right-please, for everybody's sake, don't 1924, and we think this record cannot WDAF, Kansas City Star; WCAE, let it slide into the rut. be equalIed with such a set. We listen­ Pittsburgh; WMAQ, Chicago (Chi. Daily Sincerely yours, ed between the hours of 6 p. m. and 3 News); WBAP, Ft. Worth; WJZ, New HARVEY J. DUNEKA, a. m. They are as follows: AA3, York City; WHAS, LouisvilIe; WOAI, 2641 North Central Avenue, KDKA, KFGC, KFI, KFKX, KFMQ, San Antonio; WBZ, Springfield, Mass.; Phoenix, Arizona. KGW, KH], KYW, WBAK, WBAP, RADIO AGE-"THE MAGAZINE OF THE HOUR" 37

WBAV, WBZ, WCAE, WCBD, WCK, WDAF, WDAP WDAR, WEAA, WEAY, WGY, WHAS, WHB, WHN, WIAO, WIP, WJAR, WJAZ, WMAH, WMAQ, WMC, WOAW, WOO, WOQ, Tbe 4 Latest WOS, WSB, WTAQ, WWJ, 3FA, 9BAC, 9BAQ, 9VC, WL W, WOC, WLAG, KFBC. Radio Developments We also got a Canadian steamer, the Memphis. We are a couple of radio E offer Radio enthusiasts only proven Radio develop~ nuts of 14 years. In ten months we ments. We recommend the four mentioned herein. have received 276 stations all different. You can safely order from us-we carry only the fin~ We have received stations in thirty-four W est parts, and back them with our own guarantee of states, District of Columbia, six Provinces satisfaction or money refunded. We invariably have just the of Canada, Alaska, Cuba, and Porto parts that are difficult for you to secure at reasonable prices. Rico. The night we got Alaska we wen~ using three bulbs. We are positive IF YOU ARE A SET BUILDER we heard all of these stations for our both write us to put you on mailing list. We keep you posted on the newest ears would not deceive us. instruments. No cost or obligation. Yours very truly, CURTIS SPRINGER, The "Rolls-Royce" of Head Sett 1224 N. Olney St. KENNETH FISCHER, This is the 4000 Ohm N. & K. 1219 N. Olney St., Phone fans are talking about. Indianapolis, Ind. Whether you own an ordinary Crystal or a Super~Heterodyne, And here's another list from a radio N. & K. Head Sets will greatly bug not yet in his teens which surpasses improve your reception. Made in some of the lists we have received from Germany. (Replacement parts fellows who are twice his age and who always in stock.) Extra large phones have more than twice his radio experi­ cover ears comfortably. Extra wide ence: headbands, leather covered. 6 ft. Cords. I have seen quite a few records in the Your phones are next in importance to the RADIO AGE and I think mine will receiver itself. Inferior phones make a good be.at them all. I have heard the follow­ receiver inefficient. Give your set the ing: KDKA, KYW, KHJ, KSD, chance it deserves with 4000 $8 WAAM, WBAA, WBAN, WBAP, WBS, Ohm N. &K. Phones. Soldon 50 WBZ, WCAU, WCX, WDAP, WDAR, money back guarantee. - WEAF, WEAN, WFI, WGI, WGR, WGY, WHAS, WHAZ, WHB, WHN, WIP, WJAR, WJAZ, WJZ, WLAG, Parts for New S-Tube Cockaday WLAK, WLAW, WLW, WMAK, We are among the few who can supply the essential, scarce parts for WMAQ, WNAC, WOC, WOO, WOR, this newly.popular hookup so many fans are anxious to build. WPAB, WQAO, WRW, WSB, WWJ, AMPLEX GRID-DENSER-the only Variable Grid Condenser. Per­ WMAF, WBA Y, NAA, WJY, WSAI, mits adjustment of Grid Circuit in unbroken range from zero to .0005. WCAP, WCBD, WCAE, WRC, WDT, Mfd. so you can make adjustment to the exact capacity necessary. Doubles WNJ,WTAM, WEAM, WBT, WHAM, efficiency of any tube. Gives greater distance-sharper tuning $1 25 WCAO, WJAX, WBU, WTAS, WHAR, - louder and clearer signals. Shielded. Vernier adjustment- - WOAW, WFAA, WDAF, WCAL, cannot wear out. Mounts on base or panel ...... We also carry a complete line of AMSCO VARIABLE CONDENSERS-POTENTIOMETERS WNAV, KOP, CFCA, CKAC, 6KW. -RHEOSTAT8-CARBON and LAVITE RESISTANCE8-allatlist prices. I have heard a few stations that don't broadcast any more. I have .heard eigh t amateur stations. "Radio Age" Station Eliminator I am only twelve years old and I have Not a mere "Wave Trap"-a quality product! Eliminates strongest sta­ a list of ninety-three stations in the last tion interference. This is the revolutionary discovery described in January "Radio Age" and announced by Station WJAZ. Thousands now used-everybody boosting it. When properly five months. constructed of the best materials it cannot fail. We guarantee it with Yours truly, our materials. The following parts are all you need: JOHN BENNETT, Genuine Celeron Panel...... 84c Rockville Centre, Long Island, N. Y. Celeron Drilled Tube with brass mountingbracket.50c P. S.-Will you please publish my list? Coils, double green silk wound, etppire cloth and bracket ...... $1.75 Laugh those two off, willya! And Switch Lever Contact Points ...... '" .... 35c Brockway Wide Range Condenser, (.00097 while you are laughing read this one: to .00002 MF) ...... $3.50 RADIO AGE, High Grade Cabinet ...... $2.00 Gentlemen: I think I have another good record of pickups for a two nights' try. I sent Parts for Junior Super-Heterodyne you a list some time ago, but this on~ This is the sensational hookup described in January Radio Age. Everybody has it beat a mile. I am a regular wants to build them. We carry essential parts. Rush order. radio bug, and use a Reinartz three tube 25 Turn Green Silk Honeycomb Coil, 40c set with loudspeaker. Let's get this list 500 Turn Green Silk Honeycomb Coil, $1.35 off our chest right away: KDKA, KHJ, Lattice Wound Neutrodyne Type Fixed Coupler, $2.00 KSD, KYW, KFKB, KFKX, WBAP, WRITE FOR FREE BULLETIN. (Dealer's Correspondence Invited.) WBA V, WBZ, WCAE, WCAL, WCAP, WCBD, WCK, WDAF, WDAP, WDAR, WDAX, WEAF, WFAA, WFI, WGR, RBll([J)llllf§TlflIl!M!lEN'ffS COo WGY, WHAS, WGR, WHAZ, WHB, 17 NWJ:1BJ!lSH fIVE. -. Dept. 201 . -CHICJlGO. WHK, WIP, WJAR, WJAX, WJAZ, Not the Cheapest-But the Best -Satisfaction or Money Back WJZ, WLAG, WMAQ, WMC, WOA W, WOC, WOO, WOS, WPAH, WRC, 38 RADIO AGE-"THE MAGAZINE OF THE HOUR"

\\'GY, Schnectady, orchestra . radio frequency circuits, should be of Pickups By Readers \VNAC, Boston, artists' recital from (Ctmlinued from page 37.) about 400 ohms maximum resistance, and WSAI, WSB, WSI, WSY, WTAl\I, WNAC. is used to control the bias of the grid of WTAS, PWX, WCX, WWJ, KOP, and WEAN, Providence, artists' recital the tube. amateur stations 8\\'X, 8l\1 R, 8CAX, from \\'NAC. The filament posts of the unit may be 81M, and 9XN. \\,TAS, Elgin, ILL, orchestra. connected to the common storage battery Well, folks, how about that list? It's WHAl\I, Rochester, N. Y., reading. used for t he remai nder of the set. It is about time I have a little sleep now so \VMA Y, St. Louis, address on church advisable if possible to use a separate guess I'll quit bothering you; but I want work. B battery, connecting it to the specified to say this-your magazine is a wonder. WHK, Cleveland, solos and orchestra. posts, but if no additional batteries are I do not miss it any month, as I like WRAX, Gloucester, N. J., soprana available the voltage used on the remain­ it the best of them all. It gets better solo, "Annie Laurie." der of the set may be a pplied. The voltage' every month. The only trouble is that WCB 0, Zion. ILL, xylophone and should be determined by the type of tube you don't get it out often enough. The violin solos. used, but as a general rule, about 80 list I submitted was all brought in on a WJAR, Providence, R. I., orchestra. vo lts is efficient. loud speaker-no ear phones at all. WDAR, Philadelphia, Pa., Howard Those contemplating the con~truction Very truly yours, Lannins' orchestra and "l\Iorning of this type of rejector should carefully ALBENUE DES ROSIUS, Glories." observe the rule that good results are the 256 Bridge Av., Windsor, Ontario, Can. \VHN, New York, orchestra. fru its of painstaking care in construction, WHAS, Louisville, Ky., time signal. and discriminating choice of efficient ap­ paratus. vVrite that one on your cuff! Next: WSB, Atlanta, Ga., address on A. RADIO AGE, R. R.L. The writer wishes to t ake this oppor­ Gentlemen: NAA, Arlington, Va., weather report. tunity to thank Mr. Frederick A. Smith, EditorofRA DIOAGE, Mr.E. F. McDon­ I enjoy very much reading the pickup WDAF, Kansas City, concert. columns and would like to have a few \V J Z, New York, artists' concert. a ld, Jr., of Station WJAZ for their ef­ forts in bringing the writer's article in the of my records appear in your interesting WIS, Jefferson City, Mo., Missouri publication. I am using a Hopwood state prison band. J a nu ary issue of RADIO AGE before the circuit with detector and two stages of WRC, Washington, D. c., U. S. army many fa ns, a nd wishes to acknowledge receipt of the many letters written him a mplification employing WD 12 t ubes. band. by grateful listeners in response to the re­ Although situated only 17 miles from WF AA, Dall as, Tex., concert. sults obtained from the instructions Philadelphia with WDAR, WOO, W P WOA W, Omaha, Neb., orchestra. printed in that issue. and WFI going full blast, I have tuned KYW, Chicago, Mary Garden in opera, around them almost at will. My crown­ Cleopatra. ing achievements and the ones of which KSD, St. Louis, chorus. Simple Heterodyne I am most proud are as follows: WBAP, Ft. Worth, Tex., Masonic (Continued from page 8.) orchestra. The tuning of stations WHB, WHAS, is supplied to the plate of the tube and is WLAG, SWB, WTAM and numerous WJY, New York, soprano solos. 3A YZ, Philadelphia, testing a new fed back to the grid circuit through the stations close by using a three foot loop two inductively coupled coils (N) and for an antenna. transmitter. WBZ, Shringfield, Mass., orchestra. lM). The prim1ry carryi ng the plate The t uning of KFI, KHJ, KGW, and current is (N) while t he secondary in the one morning I tuned in KFI, KHJ , and WDAP, Chicago, songs a nd market reports. grid circuit is (M). The primary (N) KGW between 12 :30 and 1 :30. contains about 60 turns of No. 26 D. C. On the night of Dec. 28 I tuned in 43 KFKB, Milford, Kans., orchestra. WMC, Memphis, Tenn., late frolic. C. wire while (M) has about twenty stations from 7 p. m. to 12:45 a . m. turns of t he same size wire. In this way (when I fell asleep at the switch). You 2XB, New York, testing new trans- mitter. the plate current frequency is imposed will find t he list attached. I also have upon the grid circuit, and the intensity a record of seventeen stations in three­ W J AZ, Chicago, quartet a nd concert. Forty-three stations in fifteen states. of the energy can be controlled by the quarters of an hour to which my better plate inducta nce or by varying the dis­ half acted as witness. Although " hear­ Total mileage, 18,501. Time, 7 p. m. to 12:45 a. m. tance or coupling between the two coils, ing is believing" I pride myself on the or both. The coil (M) should preferably fact that before I log a station I always The Pickups Editor wishes to ac­ be the. rotor of a coupler while (N) is make sure of the call letters or verify t he stator. the reception by reference to some pro­ knowledge receipt of letters from t he fo l­ lo wing readers: Next to the plate of the tube is the in­ gram as p ublished in newspaper pro­ ductance (L) which may be a SO turn grams with respect to programs. I sub­ H. J. Boyenga, Paul Baker, C. H. Peters, R . S. Merchant, B. P. Kes­ honeycomb coil. Connected across this mit a sample of my log. coil is the 23 plate variable condenser I am a red hot radio fan and could singer, P. Spencer, C. M. Bullard, H. W. Dillon , J. J. Drechsler, Max M. (C2) by which the inductance is varied write about it forever if I had the time and by which the frequency in coil (N) but I will close hoping that I have not Barnhizer, Rev. R. A. Brook, and Drew D. Mac Dougal. is varied. This arrangement can be bored you to distraction. somewhat simplified by omitting the Sincerely yours, coil (L) a nd connecting the condenser ALEX MACK. Rejectors (C2) directly across the ends of the coil 1020 Cherry St., Norristown, Pa. (Continued from page 13.) (N) .. Coil (N) is now made a 50 turn A Copy of Mr. Mack's Log Sta­ rub comes in) a nd considerable patience honeycomb. However, the results ob­ tions Tuned in on Dec. 28, 1923: wi ll have to be exercised in winding a coil t ained by this method are seldom as KOP, Detroit, Mich., poli ce reports of 2,500 turns with so fine a wire as No. good as in the complete circuit shown. and orchestra. 34. It is possible that you may fin d coil s Further increase in signal strength KDKA, E. Pittsburgh, Pa., dinner of the dimensions given in some stores is due to "tuned plate" methods, the in­ music. which handle transmitting apparatus. ductance (L) and Condenser (C2) bring­ WCAU, Philadelphia, Hotel Pennsyl- The'coil consists of the wire as men­ ing the plate circuit into or near to a vania orchestra. tioned ·'above, wound on a tube three state of resonance in regard to the grid WIP, Philadelphia, orchestra. inches in diameter. This coil has the ci rcuit. The total result of all these WFI, Philadelphia, orchestra. property of keeping the interference free systems is a circuit having excellent \VOR, Newark, bedtime stories. oscillations which we have just tUIH:d ill, range and terrific signal strength on local \VCX, Detroit, orchestra. from straying off in the wrong directioll, uroadcasting stations. The combined WCAE, Pittsburgh, orchestra. and steers them down the antenna post adjustment of condensers (C l) and (C2) WWJ, Detroit, Detroit News orchestra. of the receiver instead. The coil is an give excellent selectivity a nd broadcast­ WEAF, New York, artists' concert. absolute necessity in the unit. ing stations only a few blocks away are WOO, Philadelphia, orchestra. The potentiometer, omnipotent 111 completely eliminated when desired. I ,

RADIO AGE-liTHE MAGAZINE OF THE HOUR" 39

have repeatedly cut out the powerful avoided. The simplest and most effec­ diagram and the wires are numbered in station WJ AZ only two blocks from my tive coupler is the one shown here. The agreement with the numbering of t he home and have brought in out of town primary coil (P) consists of about 15 wires in Fig. 5. This enables the reader stations without a trace of W] AZ even turns of No. 26 or No. 24 D. C. C. mag­ to follow across from wiring diagram to during silent periods. net wire, a nd is wound on a t hree inch the isometric assembly. As the tuning of these units is very cardboard or bakelite tube. The secondary critical at all times it is advised that coil (S) consists of from 60 to 70 turns of TEN IN ONE! vernier condensers and vernier rheostat s the same wire a nd is wound on the same Ten issues of Radio Age, up to and be used. Condenser (C2) is particularly tube spaced about 5-8 inch from the end including the April, 1923, number, critical and requires very close adjust- of the primary coil (P). Do not place have been bound in heavy cloth. ment for maximum results. Both these the coils closer together than this for One of these fine volumes will be variable condensers have a maximum the 5-8 inch of loose coupling must be sent postpaid to any address with capacity of 0.0005 m. f. Trouble with . provided to obtain selectivity a nd to one year's subscription to Radio body capacity will be in evidence unless avoid capacity coupling between the Age for the special price of $3.50. The book has many hook-ups care is taken to connect the stationary two coils. and articles you may have missed. plates of condenser (C1) to the grid cir- The isometric view of Fig. 6 shows the Send money order or check to cuit. If the movable plat~s are con- typical arrangement of· the circuit when RADIO AGE, INC., nected at the end of the gnd condenser placed on a 7/1 x 14/1 panel. The vari- ' 500 N. Dearborn St., Chicago, Ill. (Kl) then the extended shaft of the con- ous parts in the isometric are lettered "Let our Hook-ups Be Your Guide" denser is at grid potential and every to correspond with those on the widng movement of the hand on this d~l will ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ detune the circuit. When a n amp lify~ Ii ing tube such as the UV-201A or C-301A is used the grid condenser (Kl) should have a capacity of 0.00025 TI1. f. The A MARVEL OF instructions for other tubes will be EFFICIENCY and found within the box. As a rule, an amplifying tube is better SELECTIVITY than a soft detector tube for this purpose, and with the UV-201A a "B" battery potential of 67 volts is very satisfactory. This makes the tuning sharper and brings. TUNING in distance much better than with the ordinary soft detector tube working with UNIT 22.5 volts on the plate. However, de­ tector tubes can be used if the plate voltage is kept down below 25 volts. The resistance of the rheostat (R) de­ FOR ANY CIRCUIT pends upon the make of the tube. While a variometer can be substituted for the inductance (L), yet it will not This new method of parallel motion, --~ perform so satisfactorily unless a fixed coupling the flat magnetic fi elds pro­ condenser of 0.00025 is connected across d uced by these coils, gives a much the terminals of the variometer. The more efficient and smooth variation of variometer only adds to the expense of mutual inductance than is possible construction and in my opinion should with the old-fashioned variometer and not be used. Besides, it is likely to in­ crease the body capacity and cannot variocoupler. easily be adjusted with vernier precision. Try this in your favorite circuit and Sharp tuning and the other desirable hear stations you never heard before. characteristics of this circuit will be lost if a very long aerial is used. In no case At your dealers should an outdoor aerial of more than or POSTPAID, 75 feet be used and 50 feet span is pref­ erable, particularly if within a few miles PFANSTIEHL SILENCER of a broadcasting station. On 30 feet Other Pfanstiehl Pure of indoor aerial I have had nearly all Inductances the stations on one tube, that is, the List Wave large broadcasting stations usually listed Turns Price Length in the "pickups" column. With this P -20L...... 25 $ .55 100-340 P-20L ...... 35 .59 125-470 short aerial, the set tunes sharply and is P-203. .. _...... 50 .65 170-650 very selective over a range of from 200 P-204. __ ...... 75 .74 220-960 to 600 meters wave length. The two P-205 ... _...... 100 .90 300-1300 P-206.._...... 150 1.10 470-1980 controls are very easily ha ndled after a Pfa nstiehl Ultra Audion...... $0.95 little practice, and as a fixed type coupler Pfanstiehl Rcinartz ...... 1.75 is used, the dial of condenser (C l) can (The Pfanstiehl Indl/rtance is a highly be logged for the different wave lengths efJective coil fIr the R einartz circuit.) and stations. Each station, when ac­ Above items at all good dealers or curately on its assigned wave length, sen t postpaid. comes in sharply each time within one or A Wave T rap using inducta nce of t he spider web two divisions on a four inch dial. t.ype, woven with great care a nd developed to A variocoupler can be substituted for high d egree of selectivity. the fixed coupler shown but it is not Ask your dealer Pfanstiehl desirable from any point of view. In t he POST- $8 00 first place the number of controls are PAID • increased, and secondly it is t hen impos­ Radio Service Co. sible to log the stations according to HIGHLAND PARK, ILL. wave length. The variocoupler taps and CHICAGO OFFICE, 33 SOUTH CLINTON STREET inductance switches add to the losses in the circuit and of course this is to be 40 RADIO AGE-"THE MAGAZINE OF THE HOUR"

The lechnica.l deparlmenl sends oul muny replies .la. ques.lians in each day's mail. !n order to assure l!rompl service la aur subscribers lhe direcl reply melhad hereafter mr;-sl be reslrlcled 10 lhose fans who. are an a.ur s.ubs~rlpllOn llsl. ~ans wh~ are. nal subscrzbers may ablain lh IS service by enclosing 50 cenls wilh lheir queslian and lhe reply will be mailed al once, accompanzed by ClrC1l11 diagram where Illustrallan IS needed. All inquiries should be accompanied by self-addressed and slamped emelape.

G. S. B., Kenosha, Wis. raising the fundamental wave of the Westinghouse Aeriola Sr., two stage autio frequency amplifier? Question: After reading your article antenna slightly. Answer: The amplifier as described in the January issue, I proceeded to build may be used as a third stage with a an Eliminator as from your description. E. S. F., Chicago, Ill. tremendous increase in volume by con­ I built this especially to be able to elim­ Question: As a subscriber to RADIO necting the output of the amplifier of the inate Zion, 111., Station WCB D. Inas­ AGE I ask you to kindly print a circuit set you are now using to the input of the much as they are only about six miles showing two stages of radio frequency Push-Pull amplifier as described in the from us we like to get them out in some amplification to the standard Armstrong January issue. The loud speaker should manner. I used a 23 plate condenser and Regenerative circuit. The circuit may be connected to the output of the Push­ constructed the windings as you specified. use either tuned or untuned radio fre­ Pull amplifier. The coil I have fitted over and around the quency transformers. condenser. I used it tonight on a try Answer: Figure 1 shows the diagram R. E. M., Stratton, Nebr. out as WCBD was shooting with full you desire. power. The Eliminator stopped them Question: I recen tly constructed a set dead, not a squawk from the station. C. T., Chicago, Ill. using the Rosenblc,om circuit which you published in the January issue of RADIO I find however, that I can't tune any Question: As a subscriber to your AGE. Your diagram calls for a .0005 MF near stations by a rather wide margin. magazine would like it very much if you condenser between the antennae and The Eliminator was hooked between would send me diagrams and information variometer. I tried connecting it up, the ground and antenna as illustrated in on a five tube outfit 2 RF and 2 AF but it made a buzzing similar to that figure 9. When I tune out WJ AZ, I amplification using a loose coupler. I caused by a loose connection. Can you am unable to tune in KYW. Why? have a standard loose coupler and 43 explain this? By leaving out the con­ plate condenser. denser I was able to pick up Los Angeles Answer: First of all I am of the opin­ Answer: A diagram of the type you and San Francisco on the West Coast, ion that you are not quite familiar with mention was printed in the November and \VJAZ, WOC, VVOS, WHB, KFKA the action of the filter, judging by your 1923 issue of RADIO AGE on page 18. and WLAG with ease. I used fifty feet of description. The tuning of t"ae filter The diagram calls for the type of ap­ ordinary insulated low tension wire requires patience, and perseverance to paratus you mention. obtain the best results. Have you tried strung around the garage for an antenna. any of the other permutations possible Is this a good performance with a single with the filter to find out about the J. M. P., Dayton, O. tube? If you can suggest a reason for the action with different connection? Also Question: Will you kindly advise me performance of the condenser will be would advise that you place a 25 turn if your Push~Pull amplifier as outlined on very much obliged. honeycomb coil in the antenna lead, Page 15 of the January RADIO AGE can Answer: The action you speak of is which assists the filter in its purpose by be added to my receiver which is of the (Continued on page 42.)

AERIAL

R

/ 200-40011.

+ 16 - 30 v + 67 - 90 v Fig. I 1

RADIO AGE-liTHE MAGAZINE OF THE HOUR" 41

tion lock effect that is harder to adjust l\.void "QRM" but more selective than the single tuned (C01tfinued from page 21.) circuit. You will find that the farther Every Question only half (or even less than half) of the the two coils are apart, within reason, tuning coil in the set, and doing your the better the selectiveness. Of course tuning with a variable condenser as I the crystal and telephone side-circuit ANSWERED have just described. should be connected across one half or Next let us take up type No. 11, the less of the coil in the original set, as ex­ plain or non-regenerative audion detector plained with regard to t he No. 12 type for only $1 used with a single tuned aerial circuit. of receiver. There are not many of these in use, so A type of No. 11 single tuned audion ..4.t last you have under one cover far as I know, but they tune best when set may be converted into a No.9 double­ a Complete Radio Handbook a series condenser in the aerial is used as I tuned set in this same way, and will be have explained for the simple crystal set. much more nearly free from interference. JUST OUT Crystal Receivers The next most selective set, as we go 514 PAGES up the list, is type No.8. This is the If your single tuned crystal set has the Comp iled by multi pIe-stage radio-'freq uency-amplifier good features described above and still outfit that uses fixed or untuned radio HARRY F. DART, is not sharply enough tuned, YOIJ must go B.S.E.E. frequency transformers. Many of the higher up the list. The easiest thing to popular "reflex" sets are made up in this Formerly wi th the do is to convert it into a type N o. 10 Western Electric: way. Nearly all of them include a set, which is the double-tuned crystal Co., and U. S. stabilizer or variable resistance for ad­ Army Instructor receiver. The most important thing of Radio. Tech· justing regeneration, but many are not you have to do for this conversation is to nically edited by sharply tuned in spite of that. It would F. H. Doane. wind a coil of about forty turns of, say, take a long time to diagnose and explain No. 24 double cotton covered wire on a the faults in design, in construction and tube 3 1-2 or 4 inches in diameter and 20,000 SOLD in operation that are common in these connect it in series with a variable con­ o more need you turn from book to outfits; consequently the most helpful denser between your aerial and ground, N book, hoping to find what you want. thing I can do is to suggest that if you which are to be disconnected from your It is all here, in 514 pages crammed full have a set of this type you can probably single-tuned set. You then connect of every possible radio detail. Written improve its selectiveness by making up the aerial and ground binding posts on in plain language, by engineers for lay­ and adding to it a separate antenna­ the set together by a wire if there is a men. Clears up the mysteries, tells you tuning circuit such as I have described variable condenser in the set. If there what you want to know. A complete in­ for the crystal set. If this does not stop is none in the receiver, you connect one dex puts everything within your reach your interference troubles you will either between these same binding posts. Then in a f ew seconds. have to improve the general design of yo u put the new coil in line with a nd IT EXPLAINS: Electrical terms and fairly close to the coil in the receiver and your set or else get another that is better circuits, antennas, batteries, genera­ or higher up the list. tors and motors, electron (vacuum) go ahead. tubes, every receiving hook-up, radio We now come to type No.7, which is and audio frequency amplification, To adjust a double-tuned outfit of the the popular single-circuit regenerator. broadcast and commercial transmit­ kind that this now is, you must have both ters and receivers, super-regeneration, A large proportion of interference en­ codes, license rules. Many other fea­ of the variable condensers at the right countered by radio listeners may be tures. setting at the same time. Of course this attributed to the inefficiency of receiving Under one cover. Yes, it is all in correct scale. reading is different for sets of this design. every wave frequency, so the double­ one volume of 514 pages of clear type tuning feature gives a sort of combina- with hundreds of diagrams and illustra­ Recognizing Voices tions. Takes the place of eleven or more Recently, a new a nnouncer handled specialized texts, each costing from two his first program through WEAF. On to ten times the dollar you pay for this LOUD SPEAKING returning home he asked his mother single boole Belongs in every radio­ CRYSTAL SET AT LAST whether she had heard the program equipped home, on every amateur's table. Stations brought in from over 1000 miles and music during the afternoon. "Yes" she re­ Send $1 to-day and get this 514-page I. C. S. heard all over the room right from your present sponded, but made no comment. A Radio Handbook-the biggest value in radio crystal set with the STEINMETZ AMPLIFIER. to-day. Money back if not satisfied. only $8.50. Write for complete information. STEIN­ little surprised he asked how she had METZ WIRELESS MFG. CO., 5737 Penn Ave., Piltsburgh, Pa. liked the announcing. Again a mono­ r -- - -- TEAR OUT HERE ------, syllabic answer. Finally he learned to J INTERNATIONAL CORRESPONDENCE SCHOOLS I his astonishment that his mother had I Box 8 781, Scranton, Penna. I not recognized his voice-so carefully I ~ n1~~ ~ 1~e ~nle4!;~~:\ ~.le~~ e R~eJ;~ ;Ii~;ctgg~ r. I Complete Set of Parts for Building had he applied the art of correct tone I It is understood that if I am not entirely I ONE CONTROL and enunciation for the microphone in I ~~~:tl~d ;'O~a\~llle~~f~ndth~y ~g~ey~v lth i n tl ve I acquiring a "radio" voice. I I On the aother hand, not many days I Name...... 1 ~ ConSlstin~~ ~~:f~l~w~ng~ET previous, another new announcer had I , Composition panel ready drilled. been heard for the first time t hrough 23-Plate condelll!er with 3·incb dial. I . ~~~ .=.. ~.= . =. .~ .. ~... ~ .. =.. = .. ~ ...::::. -.;.:... =..;,) 1 Tube Bocket, 1 base board. WEAF for a few brief special a nnounce­ 1 Micadon grid condenser and leak. 1 6-ohm rbeostat. 7 binding po.ts. ments. Later in the evening, a friend 4 ft. hookup wire. 3 ft. insulating tubing. If your newsdealer has sold 0 u r 1 Inductance coil-ready wound. who had not seen or heard of the an­ 1-.001 fixed condelll!er nouncer for more than three years tele­ his supply of Radio Age you a re 1 Pair bead pbones. t Dry cell vacuum tube. phoned a message of congratulation. I !lA" battery' and 1 B battery. likely to miss just the hook- u p tha t 100 ft. aerial wire-25 ft. ground wire. He had not questioned for a moment but you have been looking for. To 2 Aerial insulator. ground clamp and natruction .beet. that the announcing voice was that of avoid any such chance fill out the All complete, ready to assemble. only 1\ screW" driver and pair of pliers needed. his friend, so perfect and convincing was coupon in this issue and send in you its reproduction. subscription. Then you will be safe . $15.42 ogers And don't forget that with ea ch Potltage on 10 [btl. extra­ eceiving subscription at the special price of Money Back if not satisfied R adiolTleters $2.50 a year. We send you free the 39 N. Mercer St· have a record of 3,500 miles reception. popular Reinartz Radio booklet RAUSCHENBERG Greenville, Pa· ROGERS RADIO CO. FREE. Address Radio Age, 500 N. 5133 Woodworth St. Pittsburgh, Pa. Dearborn Street, Chicago, Ill. RADIO AGE-"THE MAGAZINE OF THE HOUR"

TrOll bleshooter Figure 2. (Continued from page 40.) no doubt caused by some queer freak in your wiring and arrangement of parts t o supply the necessary capacity. It might x ,ODDS- be that your condenser was shorted, causing the buzz you speak of, and when you omitted it from the circuit the remaining wires and apparatus connected to the set furnished enough capacity to offset its removal from the circuit. The list you enclosed is a good list consider­ ing the antenna you mention.

N. D. S., Mendon, Mich. Question: Can you offer any sugges­ tions how I can remedy my set Reinartz R of its habit of fading away and then coming back strong as ever again, and sometimes even stronger. I use two stages of audio frequency. I have a reflex transformer. Would like to know if I can add one stage of radio to t he present set and use that transformer. Will you send me a hookup using a limitations are caused by insufficient coils for waves from 200 to 500 meters. coupled circuit tuner with a va rio meter capacities in the neutrodons to balance Object sought-to cut out local broad· and a condenser. I want one that will the valves properly. A piece of copper casts and bring in long distance. Desire tune easy. about 1 1-2 inch square for each plate of to use 300 tube on detector if OK, and Answer: Fading, I am sorry to say, the condenser as illustrated on the en­ would appreciate a list of parts. Your is a phenomenon that we mere human closed sketch should help. Adjust the RADIO AGE is a loud speaker, and I beings cannot control, and about which neutrodons with the condenser settings at wish you great success. we know very little. If you keep your about 55. When adjusting the neutro­ Answer: I am printing in Figure 2 batteries up to the mark, see to it that no dons, it· is a good plan to pick out a good the proper connections for the parts you loose connections exist etc., it is about loud signal, or you may not find the mention. If you are having trouble in all you can do. The transformer you proper place to balance the set. cutting out local stations why not build mention will not efficiently function in one of the rejectors or eliminators as de­ the circuit. A circuit of the type you S. E. M., Washington, D. C. scribed in the January issue of RADIO desire was printed in the October issue of Question: I am a subscriber to your AGE? Thank you very much for your RADIO AGE on page 5. The diagram wonderful magazine, which I think is a comment on RADIO AGE. We hope showing two stages of amplification was great help to all radio fans, and noticing you will find it more interesting and in­ printed in the December issue. that you offer assistance, desire a hookup structive in the future. of a single tube set in which I can use G. R. S., Clinton, Ia. the following list of apparatus: 1 23 C. F. G., Jr., St. Louis,Mo. Question: I have completed the 4 tube plate condenser, 1 variometer, 1 vario­ Question: I have been trying the neutrodyne, on which I can get stations couple r, WD 11 tube and accessories. Kopprasch circuit for some time which but not loud. I can put the antenna on Answer: A circuit adaptable to your was described in April, 1923, issue but I the detector and get most of the stations apparatus appeared in the July, 1923, don't get the proper results. I sawin just as loud as without the RF. All my issue of RADIO AGE on page 19. Theset your answer to D. P. of Racine, Wis., batteries are OK, and I am using good is a regenerative one, and we have seen in the November, 1923, issue several parts. I find that I have to force the it giving very good results. suggestions as to the improvement of radio frequency tubes considerably to reception with this circuit, but after get results. \Vould appreciate your H. G. G., Long Beach, Cal. carrying them out find my results little giving me some genenl hints on the Question: Will you kindly publish changed. I am afraid that I don't quite adjustment of the set. the best known hook-up for the 3 coil understand the connections of the vario­ Answer: \Vould suggest that your Honeycomb set using Duo-lateral wound meters. That is I don't quite get what

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PAIMaRl. Figure 3. RADIO AGE-liTHE MAGAZINE OF THE H OUR" 43

Complete Corrected List of U 0 S. and Canadian Broadcasting Stations

Complete Each Issue HE list of broadcasting stations on these pages is brought up to date each month by additions of new stations and deletion ofthose which have suspended operation. The list T is the product of a vast volume of correspondence and its completeness is due in large measure to the assistance of our special news service in Washington, D. C. Suggestions, correc· tions and additional data will be welcomed from readers and broadcasters.

Wa.e K F J L Hardsacg Manufacturing Co. _____. . _...... _.. ____ .. __...... Ottumwa. Iowa 242 length K FJ M University of North Dakota.. _ __... _...... _._ ...... Grand Forks. N. Dak. 229 KFJR Ashley C. Dixon & Soo. .. ____ ..... ___.. _. . _...... Stevensville. Mont. (near) 258 ~g~~ ~::t~~~= ~~= ~ ~t ~~.=·==·.:·.~.=-==-.-.-.~.:~.-.-.-.:~f:!el~~b~~~ KFJV Thomas H. Warren ...... _...... _...... _._ .. _.. _ . _____...... De xter. Iowa 224 KDPT Southern Electrical Co .. _. __.. ___ ._...... _...... _ _ .. _...... San Die!:o. Call!. m244 KFJW Le Grand Radio CO ...... _. ... _.... _ .. _... __... _ ... _ ...... _...... Towanda. Kans. 226 KDYL . Telegram PublUh1n~ CII .....•. _ .. _ .. _.__ . ___Salt Lake City. Utah 360 KF JX Iowa State Teachers' College .. _ _.. . _._ ..•... _.; ...... _... Cedar Falls. Iowa 228 KDYM Savoy Theatre...... _... _.. _...... _ ... .:_ .. ___ ...... _.... ___... San Diego. CalIf. 252 K F J Y Tunwall Radlo Co...... _.... _.. _...... _...... Fort Dodge. Iowa 245 KDYQ Oregon Institute e! Technology._...... __ .._ ...... Portland. Oreg. 360 KF JZ Texas National Guard. One hundred and twelfth CaoaIry Fort Worth. 'l'ex. 254 K DYW Smith Hughes & CII...... __... _.. _ ..... _.... __.. _ ...... _ ... _.... :. .Pho enix. Ariz. 360 KF KA Colorado State Teachors College...... _...... _...... _... Greeley.· Colo. 246 KDYX Star Bulletin ..... _.... _... _ ..... _ ..•.. _.__ ._ ... ______.... Honolulu. Hawaii 360 KF KB Brinldey-Jones Hospital A.ssociatioo...... _...... _. .Milford. Kana 286 KDZB Frank E. Siefert.... ____.. _.... _ ...._ ... _ ..... ___... _ ... _ ... _Bakersfield. Call!. 240 K F K H Denver Park & Amusement Co ...... _...... _...... Lakeside. Col o. 226 KDZE The Rhodes Co ...._ ...... __ ..... _ .... __ ...... Seattle. Wash. 455 KFKQ Conway Radlo Laboratortea (Ben H. WoodruJI) ... _...... Conway. Ark. 224 KF KV F . F. G.ray ... _.. _...... _...... __...... _._. ... _...... Butte. Mont. 283 1~8ft E1~ctg,fc°bM~p~UbC~: .. ~~~:~:~_.~~~.~~~~~::::.-:.-:::.-::::.-:::::::: ~'~en~rcgh'~~~· ~:~tf: ~l8 ~ ~ ~~ :::;;,~r-1l ~g:. ~l::l~~iCC~ .~.~.~.~:':~.~~.~~_.~.~:_ . .-.-.-.-.-:co i ·~~~doHS~;r;:8. ~~~~ : m KFLA Abner R. Willson ... _...... _...... _... _...... Butte. Mont 283 ~ ~ tg ~~u'la l E~I"6~~eonl :-r:n ~~~~~~_~. ..~ ~: _.-.:.. :: :::. .-.:::::::::::::.~=:: . .:::: :~.¥~~~~W~~n~~~: m K F L E National Educational Senice... . _ ...... _ ...... _...... ]) enver. Colo. 268 KFLH Ericl,son Radio Co...... _ _...... __...... _...... Salt Lake City. Utah 261 1m [~~~k~~~~~~~~~~~~~~ I~ K F LP Everette M. Foster...... _.. _. . _.. ... ___. .. _...... Cedar RapI ds. Iowa 240 ~~:~ ~~':i~ge~J~~~i~~h~~rn~:t~gi o~oBofso 8f;;~1oise· ID;iii··S c~~v.-vIi~~. fda:ci ~~g ~~it l~~iW~~~;~~~~E~~~=:.:~=~~~~~~f~I~~~EEff!::~~ft[d. ~j In KFBE Reuben H. Horn .... _ .. _...... _.... __ ._...... _... _. . San Luis Obispo. Call!. 360 i~~ ~~:ilr~~~~~~r~t~~~s~ m ~ ~ ~ a r!~~t;~%d~f c~li~~~~~::::::::::::::::::=:: : :::::=:::::::::::::::::::::::: : :::: : :~fcr~tecW:: ft'":i m E~ i~ l!~~M;~;.~.~~:~~~:~~~::::::::::::~~:::::::::=:::::::::::: :::~~~~i~~~: ~~~~: ~U I( F MS Frcirr.lIth Dept. Stor"-.... _...... _...... _...... _...... Duluth. lIIinn. 275 KFBS TrInidad Gas & Eleetrlo Supply Co. and the Chronicle News J(FMT Dr. Goorge W. YOllllg ...... _...... " ...... :. .. Minneapolis. lIIino. 23 1 Trinidad. Colo. 360 J( F MU Stevens Bros...... _...... _...... _..... San Marcos. Texas 240 KFBU The Cathedral (Bishop N. S. Thomas) ...... _...... _...... _. ..Larami e. Wyo. 283 I( FMW 111. G. Sateren ...... _. ... _...... Hought.on . Mich. 266 KFCB K FMX Carleton College ..._ ...... _...... Northfield. Minn. 283 KFCD ~!r!:nE~~~~ ~~~p~. CS.···B;;rt;;~)::::=:=:::::::=-~::=::::::= :: ::::::::: ::.~':.1~~: t:~:: m KFCF Frank A. Moore ...... _...... _...... Walla Walla. Wash. 360 :~ ~ ~ i Ng:w~io~;~ aoJc .!~~~i c~liiii:::: :::::::: ::::: :::::::::::: ::::::::==::::=:::~~.~tio~~1~~· N~a~~: m KFCH KGB Tacoma Dall y Ledger ...... _...... _...... Tacoma. Wash. 25! KFCK ~~~~3o ~e~c:s S~~": d~.~~:.~.::·.::::::::::::::::::::::::coioradoBy~:s. ~~~~ m I(GG Hallock & Watson Radlo Sem ce ...... __._ .. _... __ ... _...... Portland. Oreg. 8811 KFCM ~clhmow ~~o Shop (Frank T. Doelng) ...... __...... Rlc~m~d. CJg;h ~~g KFCP ~ 8~ Seo~~~:;es~~tJc"d6~ .. ~~: ... ~~: ... ::.-::::=:::::=:.-:::::::::::=.-:::.-::g~g;,ag3: 8:fif: m KFCV KGU Marion A. Mulrony ...... _. .Honolulu. Hawaii. Wail

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zoo - 400 OHM P07ENTIOMETER RADIO AGE-" THE MAGAZINE OF THE HOUR" 45 Complete Corrected List of U. S. and Canadian Broadcasting Stations

WBAA 860 WIAU WBAD 860 WIK 360 WI:SAH 417 WBAN 244 WIL 234 WBAO 360 WIP 3GO ~~'ii~:;~~~~~;~fII~J.~Il~l~J~~~~I~~ZJ~I:~~~~:~~~ 509 WBAP Wortham-Carter PublJ.ahl.n~ Co. (::;1.41" T.I.gr..w) ...... Fort Wortb. Tex. 476 WJAB WBAV 390 WJAD 360 WBAW 246 WJAF 360 WBAX ~71fei :~~1?.. ~:~=::~~=~::=-~:~::: ::=::=:::~===::::::~~;~~e. 8:~ 360 WJAG 360 WBAY Western Electrio C ...... _ ...... _ ...... New York. N. Y. 492 WJAK 283 WBBA 240 WJAM 254 WBBD 234 WJAN 268 WBBE E~:l~~? cy~~~:?::::::::::::::::.:::.::.: ::.:.::::::: :::::.::::::::=~;:!.~~kri~.O~ 246 WJAQ 280 WBBF Georgia School of Tecbnology ...... Atlanta.. Ga. 270 WJAR 3GO WBBG Ining Ve,·milya. ... _ ...... Mattapoisett. I1Iass. 240 WJAS 360 WBL T & H Radio C9._...... _ ...... _ ...... A.nthony. lians. 261 WJAT 360 WBR Pennsylfani& State Pollce_...... __...... _._ ... _ .... _ ... Butier. Pa. 286 WJAX 360 WBS D. W. May. Ino ...... _ ... __ ...... _ ..... Newark. N. J. 360 WJAZ 390 WBT Southern Uadio Corp.... _ ...... Charlotte. N. C. 360 WJD 448 WBZ Westinghouse Eloo. & lUg. C~ ...... _ ...... · ...... ·.. _ ... ::;llringfield. Mass. 337 WJH 229 WCAD 5t. Lawrence Unherslty... _ ..... _._.. _ ...... _ ... _ ...... Canton. N. Y. 280 WJX 27S WCAE Kaufmann & Baer C.__ ...... Pittsburgh. Pa. 462 WJY 360 WCAG ClYde R. RandaJl. .. _ ..__ .. _ .. __.. _ ...... _ ...... _ .... New Orleans. La. 268 WJZ 40ii WCAH Entrekin Electrio Co._... _ ... _ ...... _ ...... __ ...... Columbus. Ohio 286 WIIllwa ul{ee. Wis. 261 WLAH 417 WCAZ Cartba"e Colle«e ._._...... _._.. _ ..... __...... _ ...... Carthage. Ill. 246 WLAJ 234 WCBA Charles W. HelmbaclL-___...... _ ...... Allentown. Pa. 280 WlAK 360 WCBD Wllbur G. Volifa.._.... _._.. _ _ ...... __.. . _...... Z1on. Ill. 345 WLAL 360 WCK Stlx. Baar & FuJler Dry Goods Co ...... _ ...... St. Louis. Mo. 360 WLAN 360 WCM University of Texas.... __...... _ ...... _._ ...... Austin. Tex. 360 WLAP 283 WCX Detroit Free Presa .. ___...... _ ...... Detrolt. Micb. 517 WlAQ 360 WDAE Tamlla Daily Timea...... _ ...... _ ...... _...... Tsmlla. Fla. 360 WLAT 283 WDAF Kansas City Star...... __..... ___._ ...... Kansas City. Mo. 411 WlAV 360 WDAG J. Laurance Martln...... _ ...... _ ...... _ ...... Amar!llo. Tex. 263 WLAW 254 WDAH Trinity Metbodist Cburcb (Soutb) .. _...... EI Paso. Tex. 268 WLAX 360 WDAK The Couranl...... _...... __._ ...... Hartfond. Conn. 261 WOAO Automothe Electrio C ..... __...... __ ...... Dallas. Tex. 360 WlB 281 WOAP Board of Trade...... _ ..... __. . _._... _ ...... Chicago. Ill. 360 WLW 360 WOAR Lit Brothers...... __._ .. _ ...... _ ...... PhlladelpWa. Pa. 395 WMAB 309 WOAS Samuel A. WaJte __...... _ ...... Worcester. Mass. 360 WMAC 360 WOAU Slocum KilburD...... _ ...... NelV Bedford. 1>lass. 360 WMAF 261 WDAX First NaUonaJ Bank (Allllameose County Farm Bureau) WMAH 360 CentenlUe. Iowa 360 WMAJ 254 WDAY RadIo E(lnlpment Corp.. _ ...... _ ...... _ ._. . _ .. _.... _...... _ .....Fa rgo. N. Dak. 244 WMAI( 275 WDBC Kirk. Johnson & Co...... ______...... Lancaster. Pa. 258 WMAL 360 woz James L. B ush. .... _.. ____._ ...... __...... Tu9cola. Ill.• Star Store Bldg. 278 WMAN 256 WEAA F. D. Fallaln ...... _...... F11nt. Mlcb. 280 WMAP 286 WEAF American Telellbone & Telegrapb Co ...... _ ...... New Yo-rk. N. Y. 492 WMAQ 246 WEAH WichitA Board of Trade ... _...... _...... Wlchlta. Kans. 244 WMAV 448 WEAl Cornell UnI.erslty...... Ithaca. N. Y. 286 WMAY 250 WEAJ Unlversll1 of South Dakota...... Vermlllon. S. Dak. 283 WMAZ 280 WEAM Borough of Nortb Plainfield (W. Gibson Buttfi.ld) WM C 268 _ ...... __...... _...... _...... _..... North Plainfield. N. J. 252 WMH 500 WEA·N 273 W MU 248 WEAO ~l:Tgargtafeo .. ·uiliv;niiiY::~:=:=:::::=:::=:::::::::::::::::: ::=::::::::::::::~c;l~~~",;'~. RO h~'; 360 WNAC 261 WEAP Mobile Radio C ..._ ...... Moblle. Ala. 360 WNAD 278 WEAR Baltimore American & News Publishing Co...... Raltimore. Md. 360 WNAL 360 WEAS Hecht Co...... _._...... _... __...... _...... Washington. D. C. 360 WNAM 242 WEAU Davidson Bros. Co... _...... _ ..... _ ...... Sloux City. Iowa 360 WNAN 360 WEAY 360 WNAP 286 WEB Wesnw~~~._ ..~~~ ....~~~~~:: .... ~~: !.:::: :::::::::::::::::::::::.~::::::S~o~~~ ~. ~~: 360 WNAQ 231 WEV Hurlburt-Still Electrical Co ...... _...... Houston. Tex. 360 WNAR 360 WEW St. Louis Unherslty...... _ ...... __. .... _ ..... _ ...... _...... St. Louis. Mo. 261 WNAS 231 WFAA Dallas News & Dallas Journal...... _...... _ ...... Dalias. Tex. 476 WN AT 3ao Carl F. Woose...... _ ...... _...... _._.... _._ ...... Syr. cuse. N. Y. 234 WNAV 360 WFAB 236 WFAF H. C. Sllratiey Radie Ce...... __...... _...... _ ...... Pou~hl'eepsle. N. Y. 360 WNAW W NA X 360 WFAH Electrio Supply Co... _...... _...... _...... _...... Port Arthur. Tel<. 236 244 WFAJ HI-Grade Wireless Instrument Co...... Asheville. N. C. 360 WNJ WOAA 360 WFAM Times Publishing Co ...... _...... _...... St. Clou1l Iwaul{ee. Wis. 280 WOC 484 WHAG Unlferslty of Clnclnnati _... _.... _...... _ ...... _...... _...... Clnclnnati. Ohio 222 WOI 360 WHAH Hafer Supply CO ..... __.. __.... _ .. _ .. _ ...... _ .. _ .. _... _...... Joplln. Mo. 233 WOI( 360 WHAK Roberts Hardware Co ...... _...... Clark.burg. W. Va. 258 WOO 509 WHAM Unlferslty of Rochester (Eastman School of Muslc) ...... Rochester. N. Y. 2a3 WOQ 360 WHAP Otta & Kuhns...... _...... Decatur. Ill. 360 WOR 403 WHAR Paramount RadJo & Electric Co. (W. H. A. Pulus) WOS 441 ...... Atlantic City. N. J. 231 WPAB 233 WHAS Courier-Journal & UruJsfUle Times...... Loulsvllrq. Ky. 400 WPAC 300 WHAV W!lmlngton Electrical Specialty Co...... Wllml ngtOll. D el. 360 WPAH 360 WHAZ Rensselaer Polytechnic InsUtule...... _...... Troy. H . Y. 380 WPAJ 268 WHB Sweeney School Co ... _...... Kansas City. Mo. 41 1 WPAK 360 WHK RadkJfox Co. (Warren R. Cox) ... _ ...... Cle.eland. Ohio 360 WPAL 288 WHN George Sehubel...... _...... New York. N. Y. 360 WPAM 360 WIAB Joslyn Automob!le Ce... _ ...... ____._ ...... TIocl{ford. TIl. 252 WPAP 360 WIAC Galyeston Trlbune... _...... _ ...... Gaiveston. Tex. 360 WPAQ 360 WIAD Howard R. MlIler...... _ ...... _...... O.ean City. N. J. 254 WPAT 360 WIAF Gustaf A.. DeCortln ...... _ ...... _ .. _...... New Orleans. La. 234 WPAU 360 WIAH ContinentAl Radie & Mfg. Co ...... _...... Newton. I owa 258 WPAZ 273 WIAI Heer Stores Co ...... _...... Sllrlngfield. Tllo. 252 WPG 234 WIAJ Fox River Valley Radle SUllllly Co. (QuInn Bros.) ... _.. Neenah. Wis. 224 WQAA 860 WQAC 3GO WIAK Journal-Stockman Co...... Omaha. Nebr. 278 WQAD WIAO School of Engineering of Mllwaukee...... _...... M llwaukee. Wis. 360 242 WQA£ 278 WIAQ ChronJele PubUshing Ce...... _ ...... Marlon. Ind. 226 WQAF WIAR Paducah E •• nim, Sun. .. __.... _ .. ___._._ ... _ ...... Paducab. Ky. 360 240 WQAH 254 WIAS Home Electric Co... _...... _ ...... _. .. _ .. __ ...... __ ...... Burlin~to n. Iowa S60 WQAL WIAT Leon T. NoeL._...... __.... _ .. ___._ ...... _...... __..... _...... _.... Tarklo. 1<10. 360 258 WQAM 360 46 RADIO AGE-"THE MAGAZINE OF THE HOUR" WITH

Condenser Construction The pamphlet contains some interesting photographic illustrations of assembled A proper soldering connection for a circuits and several diagrams. The Fixed Condenser has long been the desire Bremer-Tully Mfg. Co., 532 Canal Street, of all ma nufacturers of radio sets as well Chicago, places a price of ten cents on as amat eurs who build their own. the booklet, which is valuable to the It is, of course, comparatively easy to radio fan, whether he uses Bremer­ solder one connection to each terminal Tully products or not. of every good Mica Condenser. But the task of making 4, 3, or even 2 clean connections to a Fixed Condenser has always resulted in a very messy job. The Western Coil & Electrical Co., Racine, Wis., favors us with circulars Duostat With an evident realization of the im­ portance to clear-toned radio reception, presenting facts about two outfits pro­ T he Premier E lectric Co., Chicago, of affording the best possible soldered duced by that company. The Radiodyne recently announced a new and unusual connections and neatly soldered joints, Type W C 10, is one of the receivers apparatus. This new instrument iR the CHAS. FRESHMAN CO., of New described. Superior sensitiveness is call ed the "Duostat"-so named because claimed for this six-tube outfit. Dry it does the work of two Rheostats. The cells or storage batteries may be used. ma nufacturers claim for it many unusual There are only two adjustments. There feat ures. The windings are independent is a third knob for compensating for of one a nother. Each operates one tube. long or short balancing wires. The Simplifies wiring. The base is Bakelight receiver is of the compound circuit moulded, dial silver etched, winding type and requires nothing more than "Nichrome" wire. It is made for all a twenty or thirty foot wire for balancing types of tubes. Greatly simplifies installa­ purposes. This wire may be thrown t ion. Drill one hole, fasten to pa nel with on the floor or strung up behind the nut supplied, a nd Presto-you have a picture moulding of any room, or fi nished job for a ny 2 stage amplifier. York City have made a radical improve­ strung up in the attic. No outside ment in the design of all capacities of antenna is necessary. The outfit is Liberty Audio Transformer their Tested Noiseless Mica Condensers, enclosed in solid mahogany rub finish. which should prove a boon to man u­ The Liberty Transformer is very neatly I t weighs 14 pounds and is priced at facturers and radio enthusiasts who $150, exclusive of tubes. encased in nickled brass with a top of build and tinker with their own outfits. molded condensite. All binding posts A lug of special construction is riveted The same company produces the a re nickle and plainly marked as to by means of an eyelet to each terminal W C-5, which receives messages within terminals. The entire instrument is of the Mica Condenser. The lug is so a radius of 2,000 miles and is priced small in size, the form being upright rath­ designed that three or more different at $80. It is a four-tube circuit. In er t han horizontal. The transformer wires may be soldered to it, giving order to make it super-sensitive one takes up a space of two and one-half by exceptionally good contact and allow­ stage of tuned radio frequency ampli­ one a nd three-fourths inches of panel or ing right-angle bends. The lug is fication is employed ahead of the de­ base space and is strongly constructed. equipped with three grooves, permitting tector. It works well with an indoor I t has a ratio of five to one, which is suf­ the wires to be laid properly, and held antenna or without a high or expensive fi cient for all needs in the average set not in place while being soldered. outdoor aerial. calling for a special high ratio winding. Another most important advantage The transformer proper is well-made is that in wiring a set the connection can of good Swedish steel with the windings The rapidly increasing number of be made temporary without soldering. radio experimenters and receiver con­ well insulated and there is not the least All that is necessary is to lay the wires chance of a break or short-circuit due to structors has created a growing demand in the lugs which are so constructed for convenient tools. with which to wires being exposed as the entire trans­ that they can be made to hold the wires former is enclosed and no wires can be make and assemble sets. Among the without soldering by merely bending manufacturers who specialize in pro­ reached by a ny means. over the sides of the grooves to form a The people manufacturing this trans­ ducing such tools is the Simon & Skid· contact with the wire. In this way the more Mfg. Co., Santa Ana, California. former, by enclosing the transformer in a circuit can be tested and varied so as to metallic case, have overcome inter­ They are makers of the Simore Light­ give the most efficient results. When ning Change Tools. Their products coupling or magnetic coupling between this is attained the connections are then stages, causing howls a nd shrieks. It is include, squares, magazine screw drivers, soldered. containing three tools, and a magazine manufactured by the Liberty Transform­ The accompanying illustrations show er Compa ny, Inc., Chicago, III. tool that contains knife blade and two several methods in which the wires may screw drivers. be laid through the grooves in the lug, The Willard St orage Battery Com­ a llowing bends of various kinds. pany, Clevela nd, 0., publishes a mont hly Mahoganite quality organ, "The Connector." The publication presents fiction, trade news, In order to assist users of the Bremer­ The American Hard Rubber Company t rade suggestions, news of the com­ Tully Vernier Tuning Unit in getting asks that the following be published: pany's already famous broadcasting the most out of that instrument the "Our attention has been directed to station, W T AM, a nd excellent illustra­ Bremer-Tully Manufacturing Co. has the fact that certain manufacturers of tion!. issued a booklet "Better Tuning." radio materials and parts have recently RADIO AGE-"THE MAGAZINE OF THE HOUR" 47 Complete Corrected List of U~ s. and Canadian Broadcasting Stations WQAN ScranOOD TimelL.-... ______.. __._ ...... _._ ... ____ .SCranoon. Pa. 280 WSAT Donohoo-Ware Hardware Ca. __ .. _._._.. _ .... ____.. .PlainTlew. Tex. 268 WQAO Calvary Baptist Churoh...... __ ._ ...... _... _.. _...... _._.New York. N. Y. 360 WSA W John J. Long. jr...... _...... _._ .. __ ... _._...... _... __.. Canandaigua. N. Y. 278 WQAQ Abilene Dally ReIX>rter (West Texas Ra.dio Co.) ...... Abllene. Tex. 360 WSAX Chicago Badia Labemtery __. __ ... __. __. __.. _ ...... _...... Chicago. III 268 WQAS Prince-Walter Co .... _._ ...... _.. _.. _._... _.. _ .. _ ... _...... _...... Lowell. Mass. 266 WSA Y Irnng Austin (Port Chester Chamber .r C&mmeree) Port Chester. N. Y. 23S WQAV Huntlngoon & GUerry (Ino.) ... _...... _...... _ .. _ ... _ .... _ ...... Greem1lle. S. C. 258 WSAZ Chas Electric Shop. __... ___._._ .. ___._ .. _...... _._.. .Pomeroy. Ohio 23& WQAW Cathollc Unlverslty..... _ .. _. ___ .. __.. _.... ___. __ Washingoon. D. C. 236 WQAX Radio Equipment Co... __... _...... _ ...... _...... ____... _...... Peoria.. Ill. 360 ~~~ r:~. JE~ko-c ;=::::::=====:::.==:::=::::::::::T1i\~tB;.~. G-t ~~ WRAA Rice Institute. __ .. _.. __.. _.. __...... _ ...... _... .. Housoon. Tex. 360 WSY Alabama Power Co._._._ .. _...... __ .. ___. ____._Birmingham. Ala. 860 WRAD Taylor Radio Shop (G. L. Taylor) .... _._._ ...... MarIon. Kans. 248 WTAB Fall RiTer Daily Herald Puhliahlng C.____ ...... Fall Rher. Mass. 248 WRAF The Radio Club (IDO) ____...... _. ___.. _...... Laporte. Ind. 224 WTAC Penn Trame Co .. _ .. _ ...... _.... ~ ...... _... ______... Johnstown. Pa. 860 WRAH Stanley N. Read. ... _...... ___...... _...... _...... _.. _...... Provldence. R. 1. 231 WTAF Louis J. Galle...... __...... _.. _...... __.. ____.... _.-New Orleans. La. 242 WRAL Northern States Power CO... _.. _.. _.. _...... _...... _... St. Croix Falls. Wis. 248 WTA G Kern Music Co ... _... _ ... __._._. __ . _ .. __. _ ...... _.. Providence. R. 1. 258 WRAM Lomhard College... _...... _.. _.. __._ ...... _ ...... _ ...... _ .. __ ..... Galesburr:. III. 244 WTAH Carmen Ferro..... _.... _ .. __.. __.. ____. _____... _ .. _.Belvidere. IlL 236 WRAN Black Hawk Electrical Co ... _.. _.. _._...... _...... _...... Waterloo. Iowa 236 WT AJ The Radio Shop...... _.. _... _ .. __. ____. ___ ._ ...... Portiand. Me. 236 WRAO Radio Service Co___ . ___.. _...... _...... _._._...... St. Louis. Mo. 360 WTAL Toledo Radie & Elootrio CII ... __.. _._... ____._ ...... _.. _... Toledo. Ohio 261 WRAV Antioch College.... __._ .. _...... _ ...... ____._. _Yellow Springs. Ohio 360 WTAM W11lard Storage Battery Ce._._. ______.. _... CleTeiand. Ohi. aOG WRAW ATenue Radio ShOll (Horace D. Good) ... _.. _...... Reading. Pa. 238 WTAN Omdortf Badio Shop .... __.. ____. ______...... __....Mattoon. III 240 WRAX F1uon's Garage.. _____... ___.. _.. __ .... _.... __ ..... Gloucester City. N. J. 268 WT AP Cambridge Badie It l!Jlectrte O... __ . __. ___. __.Ca.mbridge. III 242 WRAY Radio Sales Corp___ ._ .. __...... _.. _.... __ . ____... Scranton. Pa. 280 WTAQ S. H. Van Gorden & Bw... _. ____. ____._ ...... _.... _ ... Ossee. Wi& 2211 WRAZ Radio Shop of Newark (Herman Lubinsky) ...... _...... Newark. N. J. 233 WTAR Reliance Electric Co...... _...... _____.. __... _... _..... __ .Norfoik. Va. 280 WRC Radio COl"jJoratlon of Amerlca..._...... _...... Washington. D. C. 469 WTAS Charles E. Erbsteln..... __ ...... _ ... ___. __.. __.. _.. __.... _..Elgin. III 2711 WRK Doron Bros. Elootrio Co. .. ___ ...... _...... _...... __ .. __ .Hamlloon. Ohio 360 u WRL Union Collet:e...... __...... _ ... _ .... Schenectady. N. Y. 360 ::::~L ~~~~ W~i:e~ 12 I]l=! g::=:::=::::::::=-..B~~~: ... .lf~~~~~; :~ WRM U niTerslty of Illinols... _...... _...... _... :...... _...... Urbana. III. 360 WT A W Agricultural & Mechanical C.llet:e .r Texu_._.C"llege Station. Te>:. 280 WRR City of Dallas (pollee and tire signal department) ...... Dallas. Tex. 360 WTAX Wllllama Hardware Ce...... _.. _... ___.... ___..... __.Streator. IlL 231 WRW Tarrytown Radio Research LaboraOOry (Koenig Bros.) Tarrytown. N. Y. 273 ::::~~ J~~;.!'a~. Le~~G"u~:.~~~~... ~~~~_=_=:=:Lambe~~ll!:ar~. Il}: ru WSAB Southeast Missouri State Teachers College... _...... _... Cape Girardeau. Mo. 360 WTG Kansas State Agricultural Cellege. .... _..... _. ______... .llanhattan. Kana. 4a6 WSAC Clemson Agrlcultuml College... _...... _.. _...... _... Clemson Col1et:e. S. C. 360 WWAB Hoenig. Swern & Ce. (Jllhn Rasmuaaen) ... ___...... _.. _... Trenton. N. J. 22tI WSAD J. .A.. Foster CO...... _...... _.. _...... _...... _... _ ...... Provldence. R. I. 261 WWAC Sanger Broa...... _.. _...... _...... _.. _.... _.. _.... _. ___.. __ ...... __ .Waco. Tex. 8611 WSAG City of St. Petersburg (Loren V. DaTls) ... __ ...... St. Petershurg. Fla. 244 W WAD Wright & Wright (Inc.) .. _ ...... _.. ___. __.. __.• _.Phlladelphla. Pa. 8611 WSAH A. J. Leonard. ir...... - .. - ...... _...... _.. _... _._ ...... _...... _...... Chicago. Ill. 248 WWAE Alamo Dance Hall. L. J. Crowley..... __..... ___...... _...... Jollet. III 227 WSAI United States Playing Cards C •. _...... _. ___.... __ ...... Cincinnatl. Ohio 309 WWAF Galvin Radio Supply CtI. .. _...... _.__ ._._.__ . ___ .Camden. N. J. 218 WSAJ 360 WW AO Michigan College of Mines_. __. __.. _. _____._ .. Houll'ht<>n. Mioh... _244 WSAL 246 WWI Ford Motor Ce ...... _...... __ .. ____._ ...... Dearborn. Mich. m WSAN ~~~i:Mi:J~¥ei.~.~~::::::.~:::::::::=::::::==:.:=::::=:::::::.~~::::::!E~=. I~~ 229 WWJ Detroit News (ETening News AaIIIl.)_.. ____... __ .Detroit. Mich. 1117 WSAR Doughty & Welch EleatrWal Co. ... ____. ___.lJ'all RiTer. Mass. 254 WWL Loyola UnlTerstty.__ .. __... ______. __.. .New Orleans. LA. 288 Canadian Stations CFAC CHCL ...... _ .... _...... __ •__ •__ . ______• ____ .. VanceuTer. B. C. 440 CFCA CHYC Canadian Nerthern Elee. ___ . ______..... Montreal. P. Q. 410 CFCF CJCA Edmonton Journal. Ltd._. ______... ___ ..Edmonton. Alta. 480 CFCH ~E!~Abitibi Power~~~:~:!.:.:.~~·:.~:·::~:~:::::~·:·::=?:·:=:::~~~:::==·.MO~i~¥!:p.t~~· & Paper CII. Ltd...... _.... __.. _.Iroquois Falls. Ont. 400~g CJCD T. Eaten Co...... _._.... _ .. _ .... ______. __. __ ...... Toronu,. Ont. 411 CFCI ...... _...... _._.. __ .. _ ... _.... _ .. _...... _...... ___ .. __..... _Vaneomer. B. C. 410 CJCE Vancouver Sun... _...... _...... _ .____ . __.. ___... _Vancouver. B. C • 420 CFCJ ... _...... _... _...... _...... _... __ ..... _ ... _.... _._.... __... _... _...... Quebec. P. Q. 410 CJCI McLean. Holt & Ce .• Ltd._. ______. ___.... St. John. N. B • 400 CFCK ...... _...... _____ ...... _... __.,_ .... __ .. _...... Edmonton. Alta 410 CJCN Simmons. Agnew & Co...... _ ...... _.. _. ______...... _.Toronu,. Ont. 410 CFCL ...... - ...... - ... --.-...... _. __.. __ ...... Vlctoria. B. C. 400 CJCX ...... ____.... ___... ____...... Olds. Alta. 400 CFCN W. W. Grant Radio. Ltd... _...... _...... __._._ ...... Calgary. Alta 440 CJ G C London Froo Press...... _._. ___ ._._... _____._ .. __ ...... _London. Ont. 430 CFCO ...... ___ .... _...... _..... _... _...... _...... _.__ ...... Belleme. P. Q. 450 430 CFCW ...... _... _...... _ ..... _.. _...... _... _...... Lendon. Onto 420 gksfc EL:nip~es~~.~~~.~.::::::::::::=.=~===--=-..:.::=-_:_.:::::y~~~~~~~.P.O~ 430 CFQC ...... _...... __...... _ .... __ .. _..... _...... __ ...... _ .. __ ..... _... Saskatoon. Sask. 400 CKCD VancouTer Daily ProTinee.... _____.. _ .. _. __._ ...VancouTer. B. C . 410 CFUC ...... _...... _...... _.. _ .. _._ ...... ___...... _._...... Montreal. P. Q. 400 CKCE Can. Ind. Telephone C... _. ___. __.... ____... _...... T<>ronu,. Onto 450 CHCB ... _ ...... __._ ...... _ .. _...... __...... _.... _...... Calgary Alta. 410 420 CHCD ... _.. _ ..... _...... _.. _.. _...... __ .Quebee. P. Q. 410 g~g~ ~:n~o~ubtm~g s~~pi;.. ·c.:-..:.:.:.:=:..-:..-:..--==.=.:::::::."i[~.:fi:~. S~~ 410 CHCE ...... __..... _...... _._·_.... _... _.. _ ...... _.... _.... _..... _... _ .... __ ... VlctorIa. B. C. 400 CKY ...... _.. _.... _.... _.... _ .... ____.... _____ ._ .. W!nn1per:. Maniooh& 480 started to use the name 'Mahoganite' demand for a high-grade, dependable New Crosley Factory on some of their devices. This name is grid leak. It is similar in external In order to meet the demand for Cros­ one of our trademarks for radio material appearance to the Universal Bradley­ ley-made radio receiving sets, Powel and for panels, dials and other radio stat and is equipped with an adjusting Crosley, Jr., president of the Crosley parts. Realizing that the unauthorized knob Which conforms, in general design, Manufacturing Company, has purchased use of this name by others in the past with the approved tapered knob now the four-story factory building now oc­ may have been inadvertent, we are taking used in most radio equipment and match­ cupied by the Thomas J. Corcoran this occasion to bring to the notice of the es perfectly with the adjusting knobs of Lamp Company, on Colerain Avenue at trade the fact that we own the exclusive the Bradleystat and Bradleyometer. Sassafras Street, in Camp Washington, right to the use of the name 'Mahog­ The Bradleyleak can be adjusted Cincinnati. This real estate transaction anite' for radio materials and parts and between the limits of 250,000 ohms and involving more than $150,000, surely that we shall look upon as an infringer 10,000,000 ohms or, as usualIy stated, meets the question of whether the radio anyone who uses this name upon similar between one-fourth megohm and ten industry is an established business or a products." megohms. The entire range of grid leak passing fad, for preparations are being resistance between these limits is instant­ made to manufacture nearly 5,000 radio ly obtainable without noises, steps or J;"eceiving sets every day in this new An attractive booklet is issued by the jumps by simply turning the adjusting plant which will be ready for occupancy Atlantic Radio Electric Co., 308 South knob. It is a significant fact that all by early spring. Clark Street, Chicago. The pamphlet intermediate values of resistance can be The large building will house, in addi­ contains illustrations and descriptions accurately obtained at any time which tion to the general offices, manufacturing of the well-known "Bestone" radio is a feature not often found in many and assembling departments of the merchandise. This line is a complete types of adjustable grid leaks. Crosley radio products, the radio broad­ one, including everything from complete The base of the Bradleyleak is recessed casting station, WL W, which will have tube and crystal sets to switchpoints, to receive a small fixed condenser which alI of the latest improvements of this variocouplers, variometers, headsets, is furnished as an extra attachment if particular field in the radio world, mak­ condensers, and transformers are pa rtic­ desired. The grid condenser is accurate­ ing the station one of the finest in the ularly well presented and attractively ly adjusted to a capacity of 0.00025 world. priced. microfarads. There is a floor space of over 100,000 square feet in this new four-story build­ "Battery Charger" ing, as compared with 30,000 in the pres­ ent Crosley factory, at Alfred and Col­ New Grid Leak (Contin ued from page 28) erain, and this large space will be fulI y directly to the alternating current mains utilized with the manufacture of radio The Allen-Bradley Company, manu­ "lnci the secondary directly to the rectifier. recelvmg apparatus. It is the intention facturers of the Universal Bradleystat The voltage of these toy transformers is of Mr. Crosley to manufacture radio and Bradleyometer, have added another usually adjustable, so that the rate of parts in t he present building and to item to their line of graphite disc radio charging may be regulated by the con­ use the new one for the making of the products. trolIing switch on the secondary of the complete outfits. There is a B. & O. and The .lew device is an adj ustable grid transformer. This method will charge Southwestern Railway company siding leak, known as the Bradleyleak, which the battery faster, and is much more which goes to the plant, facilitating the was developed to meet the insistent efficient. shipping of the raw and finished products. 48 RADIO AGE-"THE MAGAZINE OF THE HOUR" Reinartz Adap­ tions (Continued from page 6.) Queer as it may seem, the use of radio frequency amplification with the Rein­ ERLA BLUE PRINTS artz circuit is not always according to "Hoyle," but if care is exercised in con­ structing the set, the results are partic­ ularly gratifying. Erla Receivers out-distance other sets with an almost The reversal of the reactance coil marked "x" in the diagram is often nec­ unbelievable volume and a naturalness that cannot be essary when a second tube is added for distinguished from the source of reception. radio amplification, but is a matter of ex­ perimeht. One experimenter winds the entire Reinartz inductance on a 3-inch This is the famous Erla Reflex Hook-up. Less than cardboard tube according to the regular specifications, but instead of placing the one year old-but has taken the entire nation by storm. plate coil winding "x" alongside of the Every listener-in raves about it and wants a set of his antenna coil, winds it on a separate small­ er tube and inserts it inside of the larger own immediately. coil. The winding should be in reverse direction to the larger antenna grid coil. The circuit shown makes use of the tuned So easy to construct that anyone who can handle a impedance type of radio amplification, screw driver can build the set complete in a sur­ which is highly efficient in covering a large band of waves. prisingly short time-about 1 1-2 hours. Everything Figure 4 shows the method used by an English amateur who uses the Reinartz IS so simple and easy. hookup for obtaining the best results with radio frequency amplification. With the exception of a few changes in con­ A stants it is practically the same as that of NO SOLDERING WHATEVER-ONLY Figure 3. He, however, uses only 1 B battery, and gives the following specifica­ SCREW DRIVER NEEDED. tions for the winding of the coils. The entire coil is wound with No_ 22 The results from the Erla 3 tube is naturalness itself and can­ Dee on a 3-inch tube. Ten turns are first wound with taps at every turn. The not be improved upon. Actual size working diagrams make tenth tap connects to the potentiometer and ground. Twenty additional turns every thing simple and easy. Every piece of apparatus and are then wound and a tap is taken off every wire is pictured in its exact place-every article needed for the grid switch, then fifteen more are wound, and last the coil is completed with lS listed on the diagrams. fifteen more, making the total number of turns from the tenth tap of the antenna coil to the last grid tap fifty turns. Diagrams sent same day your order is received. The plate coil should consist of 40 Send P. O. or Express Money Order or Bank draft t urns of the same size wire wound on a smaller tube, in the opposite direction to or Bank Cashier's check. Do not send stamps or the a ntenna-grid coil. This smaller tube is inserted at the antenna end of the personal checks. larger coil, as mentioned before. The auto transformer coupling arrange­ ment consisting of 36 turns of No. 16 wire on a 3 inch tube should be placed at right Erla Hook-up Diagram Prices angles to the grid inductance, and as far away as possible to offset any inductive 3 sheets for making 1 tube set 2Sc effects which might exist. If an audio frequency amplifier is 3 sheets for making 2 tube set 3Sc added, it is necessary to leave the phones connected in the plate circuit of the de­ 3 sheets for making 3 tube set SOc tector, in order that the phone resistance may act as an impendance. The writer hopes that these suggestions may develop some successful long dis­ tance receptions with two tube Reinartz Frank D. Pearne sets, and would be pleased to hear from fans with regard to any new kink~ or Sole Distributor of Erla Diagrams for U. S. and Canada wrinkles they may chance to discover in working out these circuits. 829 Waveland Avenue, Chicago, Ill. Dealer., Write for Quantity Prices Don't Fail to renew your subscription!

• ... ~ , . ~ .. ;. ~ '-1 -:" . _ ~ _ _ _ _ 0( • r' ze sc .. e $C )e n n .. [ You want RA D lOA G E each month [ You want the [ Great Radio Age Annual for 1924 (IT IS THE BEST AND MOST COMPLETE HOOK-UP BOOK

[ You Want to Save 50 Cents - We Want 100~OOO Circulation [ [ H 0 VV! [ Having gained approximately 35,000 in four months and having added materially to the quantity, quality and appearance of our magazine we have not increased the subscription price, although we are told by thousands of fans that our periodical pre­ [ sents the best isometric drawings and wiring diagrams and the most timely, instruc­ tive articles available anywhere. You, yourself have just read this number of Radio [ Age. We are printing magazines like this every thirty days. You cannot always get Radio Age on the news stand. Dealers sell ou t in a hurry. As we were about to go to press for this issue we were still receiving telegrams and [ letters from dealers asking for new supplies of the January issue. (Did you read that now famous wave-trap article on tuning out interference-four pages of information with ten crystal-clear illustrations?) If you are a subscriber we insure delivery each [ month. How about that 50 cents?

That's where the Radio Age Annual for 1924 comes in. You get this fine col­ lection of all the standard hook-ups, with page after page of the best Radio Age drawings and the clearest instructions on how to build any standard set together with a year's subscription to Radio Age for only $3.00. We have put a rock bottom price of $1 on this Annual and the regular subscription rate is $2.50 a year. Don't let the low price of $3 for magazine and book scare you off. You will thank us when you get that book! ~E1i IGe==9E1i 'Eli IEle==3Bi =~'~~~~~~~~~~~ I!lr El' 'Elr=;;;;;;;oEl' 'Ei' '.,' 'EI'" ~~ All· Standard Hookups in

~rnl .. " . One Book $1.00 mill N oT a collection of difficult diagranls with scanty scraps of instructions Wrnl but a big volume of illustrations and complete construction details mw. that will tell you all you need to know to build ANY KIND OF A rn.:l STANDARD RECEIVER at home. ml ~.I Picture-diagrams (isometric) that show even the radio novice where to place rn.:l the parts and how to connect the wires. These drawings are copyrighted B~ and you cannot get them elsewhere than in this book. ~W Everything is explained and illustra :~ ed, from the crystal set to the super­ EI heterodyne. It is an up-to-the-minute guide for the radio experimenter ~ who wants the oldest, the best and THE LATEST, Simple Crystal Set Reinartz Long Distance Crystal Set Hopwood Your First Tube Set Haynes Kopprasch Circuit Cockaday Erla Reflex Neutrodyne Kaufman Three-circuit Tuner Grimes Inverse Duplex · Super-Heterodyne Two Stage Amplifier Simple Radio Frequenc,. Junior Heterodyne Ultra Audion One Tube with Loop Aerial Rosenbloom Wave Trap, Filter, Eliminator Push-Pull Amplifier Loading Coils Portable Reinartz Transformers Wave-Meters Code Instructior- T w o-Circuit Crystal

HE foregoing is only a partial list of the good things in this book. TYou can learn the wireless code, or make an interference preventer; in fact, turn your workbench into a complete home laboratory. Hundreds Sold Before the Presses Started! First 5000 Ready Now! EARLY ORDERS MEANS EARLY DELIVERIES!

Send only $1 as payment in full to address below. Send money order, check, currency. If by check add 5 cents for exchange. Nothing else like it, Nothing else as good as "THE RADIO AGE ANNUAL For 1924 Make all relnittances to RADIO AGE, Inc., 500 North Dearborn Street, Chicago, Ill. Radio dealers, news dealers and bookseUers, write for price. Scanned from the collections of The Library of Congress

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