In This Number Important Factors in the Construction of a Super­ Heterodyne.

A Universal Amplifier.

Complete I nstructions for Building a Sure - Fire Reflex Set.

Radio Age Data Sheets.

Corrected List of U. S., Canadian and Cuban Broadcasting Stations.

How the Fight to Tax Radio Failed. pjckups and Hookups by Our Readefi.

Up-to-the-Minute News Pictures.

Au then tic Radio Diagrams.

Other Timely Features. Your Radio Problems Solved for 30 Cents in Stamps

F YOU a re constructing a receiVIng set, and you need help in the way of clear diagrams and I full detailed descriptions you may have it by return mail. \Ve have laid aside a limited number of back numbers of Radio Age for you. Below 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. \Ve advise immediate attention to this as the stock of back numbers of several issues already has been exhausted.

May, 1922 January, 1924 -How to make a. simple Crystal Set for $6. -Tuning Out Interference-Wave Traps-Eliminators- Filters. wJk~~rtic1e which was announced from stations WJAZ. woe and -A Junior Super-Heterodyne. October, 1922 -Push-Pull Amplifier. -How to make a Tube Unit for $23 to $37. -Rosenbloom Circuit. -How to make an Audio Frequency Amplifying Trans- former. February, 1924 -How to make a battery charger. -Improved Reinartz Circuit. November, 1922 -Interference rejectors. -Photo-electric Detector Tubes. -Single Tube Heterodyne. -Design of a portable short-wave radio wave meter. -How antenna functions. -Adding two audio stages to selective receiver which began as a crystal set. -Superdyne receiver. May, 1923 -How to make the Erla single-tube reflex receiver. March, 1924 -How to make a portable Reinartz set for summer use. -An Eight-Tube Super-Heterodyne. -A simple, low loss tuner. -Junior Heterodyne Transformers. -A Tuned Radio Frequency Amplifier. June, 1923 -How to make the Kopprasch Receiver. -How to build the new Kaufman receiver. -Adding Radio Frequency to the Variometer Set. -What about your antenna? -Simple Reflex Set.

April, 1924 July, 1923 -An Efficient Super-Heterodyne (fully illustrated). -The Grimes inverse duplex system. -Selecting the Right Receiver. - How to read and follow symbols. -A Ten-Dollar Receiver. -Proper antenna for tuning. -Anti-Body Capacity Hook-ups. -Radio Frequency Amplification. -Reftexing the Three-Circuit Tuner. -Index and first two instalments of Radio Age Data September, 1923 Sheets. -Simple Radio Frequency Receiver. May, 1924 - Construction of a Simple Portable Set. - An Ideal Set for the Summer Camper. December, 1923 - A Traveling Man's Receiver. -Building the Haynes Receiver. - Radio Panels. - Combined Amplifier and Loud Speaker. - Making a Baset-\Veave Tuner. -A selective Crystal Receive r. -Third Instalment of Radio Age Data Sheets.

RADIO AGE. Inc. 500-510 North Dearborn Street CHICAGO, ILL. dio COInpanion A six-tube set completely self-contained! No need to open case to operate No exterior loop or antenna required

Zenith - MacMillan's Choice Encased in a Light T.raveling Bag! Here's a six-tube radio set that's entirely panionshlP it could give you on your self-contained-tubes, "A" batteries, motor parties-at the bathing beach. Pic­ "B" batteries, loud speaker and loop ture the enjoyment it could bring your antenna complete, and it's a Zenith! guests at the house-party or the week­ Packed into a small, beautifully finished end gathering. traveling case-much smaller than the Again, think how such a set would average suitcase-this new Zenith is the while away a lonesome evening in that most compact set ever made giving dreary out-of-town hotel- what a god­ clarity, quality, volume and distance. send it would be to that invalid mother -to that dear relative or friend who must Do you see those two little buttons close to the handle? Those are the spend w eeks and months in the hospital! controls. In order to operate the new But if you have already been initiated Zenith Radio Companion you simply tum into the wonders of the Zenith, you don't the controls to bring in the station you need be told the extraordinary use you could get from this new m odel or the fu n it could want-then for maximum volume you give y ou. swing the case so that the loop is facing Just the knowledge that you cou Id pick u p this that particular station. You will be aston­ beautifully finished case -even as you would pick ished at the clearness with which the u p your hand bag-and take it with you across city, country, lakes, mountains, and still turn those music and the voices come through - and two controls and be able to liste n at a moment's in what volume ! notice t o t he· world you have left behind-that Think what it would mean to you to though t alone should be enough to sugges t th e infinite delights p rovided by this new Zenith 'Radio be able to take one of these new Zeniths Com panion with you on your travels and outings. You will want to know more of this remarkable A real radio set-the exclusive choice of set-so ligh t and com pact, so easy to opera te, so Donald B. MacMillan for his Arctic ex­ wonderfully convenient. You will want to see it pedition-yet so compact that it takes up fo r yourself, at t he very earliest moment. N o ear­ p h on es,you u ndersta n d. N o outside antenna. Yet no more space than a light traveling bag! clarity, volume, quality, dis ... Think of the fun you could have w ith tance ! A real Zenith, packed th is set- the dance music you could listen '1nto a tr aveli ng case! Your name and address l-;ENITH ;;DIO C~RPORA TION,- l to on moonlit nights-the orchestras that on the cou pon, and the cau .. I D ept.2 - F , 328 S. Michiga n Ave., Chicago, III. I would play for you a s you and your pals pon placed in the mail, will Gentlemen: I gathered round the camp fire-the com- b ring you full particulars. I Please sen d m e illus tra ted litera ture on Zenith t R adio, including full pa rticula rs of the new Z e nith I I R adio Com panion. I

Zenith Radio Corporation I Name ...... I Rt:celvlne: the latest mar.. k e t report s . the lates t McCormick Building I I news deve)()pments, w ith I Address ...... I the aid oftheZen\th Rad io Companion, Chicago, Illinois I ...... '='==='==.:::==='::'=J Always A/ en/ion RAD IO AGE Wizen Writing 10 Advertisers 2 RADIO AGE f or June, 1924 The ~lagazine of the Hour

RADIO AGE A Chat With The Alagazine of the Hour the Editor Established March, 1922 1------______1 HILE there may be a slack­ I ing up of const;uction work T?o/U11/e 3 JUNE,192-1 NUlIlber 6 W during the hotter weeks of Summer, -it is already quite evident as we go to press that the radio public is not losing its interest in CONTENTS reading about radio. It does not seem to require much training be­ Page fore the fan is able to get amuse­ Important Factors in the Construction of a Super- ment and real instruction out of the Heterodyne ...... 5 mere studying of wiring diagrams. By F. D. Pearne \\'hile the practice of one's knowl­ Automatic Filament Control ...... 8 edge of hook-ups may be tem­ By Roscoe Bundy porarily suspended, there is still a deal of enjoyment in contemplating A Universal Amplifier...... ' ...... 9 the theories. By Felix ' A nderson That is why we are again offer­ A ll Together for a Radio Summer ...... 11 ing, in this June number, a variety A Sure F ire Reflex Set. .. : _ ...... 13 of technical articles with the usual By R. J. Robbins helpful illustrations. Broadcaster \\Tins Copyright Suit...... 17 I t is apparent that much of the public interest IS centered on the The \,Vhy of the Heterodyne ...... 19 By John B. R athbun super-heterodyne. This outfit, here­ tofore ayoided by many because of A dding Radio and A udio to Baby Heterodyne ... 21 the expense involved tn putchas­ By John B. R athbun ing a sufficient number of tubes \ Vhat the Broadcasters A re D oing ...... 23 and other accessories, is being sim­ Radiotoria Is ...... 25 plified with a Y1eW to reducing the number of tubes needed. It is only P ickups and I-l ookups ...... 27 a question of time when the supe~­ By Our Readers • h eterodyne will be within the reach Radio Age Data Sheets ...... 37, 39 of the average fan, hoth as to cost Radio \ \Till Kot Be Taxed ...... 38 and to construction and operation. T he Trouble Shooter ...... 42 l\1eanwhile the regenerative, the \\' ith the l\ Ia nufacturers ...... 46 Reinartz and several others of the standard circuits, such as the re­ Corrected L ist of Broadcasting Stations ...... 50 flex, claim the attention of a vast 11======!lumber of home experimenters. The old fable that something" may be invented tomorrow that Radio Age is published monthly by will make the receiver of today RADIO AGE, Inc. look like a wheelbarrow in an auto­ mobile show, IS still popping up Ad vertisin g, Editorial and Publication Offices, occasionally. Let us make the pre­ 500 N . Dearborn St., Chicago diction that for a long time to come new developments in radio wil! L oUIS L. L E VY, Cirrulatioll Malla ger FREDERICK S:\IITH, Editnr find their birth in patient, deliber­ F R.\NK D. P EA RNE, Technical Editor ate experimentation. Radio is still 1\1. B. SMITH, BIISill l'"ss Mallager an infant art, but R ome was not Eastr.r1I Represelltativ('s built tI1 a day. \Ve ask that you DAV IDSON & HEVEY folIo\\' our writers in their discus­ 17 \Vest 42nd Street, l\cw York City T elephone, Longacre 1693 sions tI1 future Issues of the 1111- provements and discoveries as they . Adverti;;i ng form s close on the 15th of the month are made . precedin g date oi iss ue Applicants for member>hi p in A. B. C.

Issued monthly. \ ' 0 1. J. No.6. Subscription price. $2.50 a year. E ntered as second-class matter April 4. 1924. at the post o ffi ce a t Chicago. lIIinois. under the act oi March 3. 1879.

Cop yright, 1924, by RADIO AGE, Inc. -Editor, RADIO AGE "THE AIR IS FULL OF THINGS YOU SHOULDN ' T MISS "

NO.7II1 .. lYD~d6ell Tbe best battery for use witb dry cell tubes

More Power for Summer Radio WHEN you take radio away with you-take Eveready multiple for each WD'II or WD'I2 tube-this gives Radio "A" and "B" Batteries, the batteries whose the economical "eighth" ampere drain per cell which great power lasts longer. Remember, summer's the insures maximum economy and longer life. For sets time when radio signals are weaker. employing one to three UV'I99 tubes use three Batteries do get used up in time. The ones you've Eveready Dry Cell Radio "A" Batteries No. 7II1 been using, though partly exhausted, may be satis· connected in series. factory for the strong winter signals, but are prob· The greatest electro,chemical laboratory known ably inadequate for the weaker summer signals. created these famous dry cell batteries on which radio For instance, use the familiar standard 22.%,volt largely depends. The experience of thirty years in Eveready "B" Battery No. 766. It has variable taps battery making stands back of them. for "soft" detector tubes. Put two, three or four Eveready Radio "A" and "B" Batteries-lively, in series to provide sufficient power for amplifiers. peppy, long,lived producers of power. To light the filaments of your dry cell vacuum For your light,weight sets to take camping or on tubes for the longest time, use Eveready Dry Cell hikes, Eveready has suitable small batteries. Radio "A" Battery No. 7III. The Eveready "A" Manufactured and guaranteed by will astonish you by its long,sustained vigor. It is NATIONAL CARBON COMPANY, INC., New York-San Francisco HeadquaTuTs fOT R adi o Batury Information advisable to use two Eveready "A's" connected in Canadian National Carbon Co., Li mited, T oronto, Ontario

Informative and money-saving booklets on radio batteries sent free on request. If you bave any questions regarding radio batteries, write to G. C. Furness, M anager, Radio Division, National Carbon Company, Inc" 2 0 2 Orton Street, Long Island City,N, Y.

Eveready 6-volt 5~A·~e Battery

"Brj"Bal~:ry - they last longer

A lways Menlion RADJO AGE When Writing /0 Advertisers 3 4 RADIO AGE f or June, 1924 The Magazine of tbe Hour

Kadel & Herbert Pho to. FIRST AID TO THE SHIPWRECKED The S. S. "Columbus" is the first ocean liner to carry lifeboats fully equipped with radio receiving and transmitting equipment. The set shown above, a power­ ful one capable of receiving stations several thousand miles away, is placed under the prow. Officers are rigging and hauling up the antenna on one of two motor lifeboats equipped with radio. . RADIO AGE for June, 1924 The J¥agazine of the Hour 5

!FBI IBI IBI IBI IBI 181 IBI IBI 181 1(:)1 IBI IBI 181 IB1 ~ . ~C1~ ~ ~ MagaJine !!ftne Hour ~

I::J M B S . h A Monthly Publication F d . k S . h I::J mit Devoted to Practical re eriC A. mit ~ Business.. Manager Radio Editor l- EI lEI IBI IEI' lei IBI IBI IBI IBI IBI IBI IBI IBI IElE! Itnportant Factors in the Construction of the Super... Heterodyne By FRANK D. PEARNE

LTHOUGH many new receiving sets he wants, and that only, he stops experi­ the building of a super~heterodyne set, have appeared during the last year menting on receivers, for he has reached claiming that they would not work, but A and a half, some of which are the top of radio reception. whether this is caused by the assembly claimed to pick up any station within a Because of the apparent expense in­ of parts which are not well suited for each radius of three thousand miles, it is doubt­ volved in the construction ·of the super­ other, or whether some of the manufac­ ful whether or not any of them can even heterodyne many of the old timers have turers are not careful enough in the se­ begin to compare with the Super-Hetero­ hesitated about building it, but when the lection of these parts, is a question and dyne. Ask any radio man of experience whole thing is boiled down to just what is it is in the hope of clearing up some of what he would suggest as the best pos­ this trouble that the following specifica­ sible set and invariably the answer will tions are given. be, the super-heterodyne. It was this type of receiver that first made it possible How the Super-Heterodyne Works . to reach across the ocean and when prop- Distant reception is best accomplished erly constructed and operated, its per­ by the use of radio frequency amplifica­ formance has never been equalled, this tion, used before the signal is detected. fact having won for it the title of "king By using several stages of this type of of them all." amplification ahead of the detector it is Just why· should this arrangement be possible, according to theory, to pi~k up so far ahead of everything else of its very weak signals from great distances kind? It is not new, but it is only within and so amplify them before detection that the last year that its real value has been they can be heard as well as local sta­ appreciated, but one reason for its sudden tions. This theory would work out very popularity is the fact that its construction nicely if all the broadcast waves had the is based upon good sound logic, but while same frequency, but unfortunately this it has never met its peer, it must be re­ would make it impossible to tune in any membered that in order that it may pro­ particular one, and as any radio frequency duce the remarkable results which are transformer, such as is used in this type claimed for it, the greatest of care must of amplification, will have one particular be exercised in its construction and even frequency at which it will operate at its when this is done one must not expect greatest efficiency, then it may be readily to learn to handle it as easily as he can seen that one certain station sending out operate other receivers. waves at just the particular frequency The operation of this receiver is an art best suited to the type of radio frequency and will require considerable patience on used would be heard with remarkable (he part of the operator before he will clearness and volume and all the rest of be able to tune it quickly and sharply to +A -A +8 the stations using waves of different fre­ any desired wave. When playing with the quencies would come in poorly. · dials, even the most unsophisticated ama­ Figure 2. A diagram of the Hartley Now the super-heterodyne, as will be teur cannot help but realize that he has Oscillator. explained later, consists of a method of before him something very unusual, for changing the frequency of any incoming · he will hear every thing known to broad­ wave to that best suited to the radio fre­ cast programs as the dials are moved actually needed in the way of apparatus, quency transformers used. That is the slowly around, but to select and bring in much of it can be made at home with signals, no matter at what frequency ' they any particular one of them is a different ordinary tools and in many cases this come in, are changed in any case to one story. They are all there and with them home made apparatus will give better re­ common frequency, so that any of them is a strange collection of sounds and sults than factory made parts. The object selected will always pass through the · noises such as he never heard before, of this article is not, however, to describe radio frequency transformers at the same .and it will take time and patience to learn the construction of the set, but rather to frequency, which is that at which they :just how to bring them in loud and clear explain the action of some of the most function at their greatest efficiency. This and to lose the weird sounds that seem important parts, so that the builder may is called the intermediate frequency. It to accompany the programs. When by know exactly what he is doing. N umer­ has been found that these intermediate constant practice and study, he gets so far ous complaints have been received from frequencies should be those of much advanced that he can bring in just what our readers who have purchased parts for greater wave length than those for which 6 RADIO AGE for June, 1924 Tlze A1agasine oj the 1l0Zlr

the ordinary radio frequency transformer is constructed, consequently those used in the super-heterodyne must be of special design. Experiment has proven that these inter­ mediate frequencies should be of wave lengths of from 3,000 to 10,000 meters, it of course being understood that what­ ever wave length selected from this range is to be the fundamental wave length ~ of the transformers used, and does not mean that the transformers will operate ~ ~OQ!IOQ{l\lIl"'--~~1 II~:~--""" on any wave length from 3,000 to 10,000 meters. If the transformers to be used " are of the iron core type, then because of their greater re-actance at the higher frequencies, those frequencies having from 3.000 to 6,000 meter wave lengths are usually chosen, but if the transformers are of the air core type they can be de­ signed for the higher wave lengths. In purchasing or building these long wave transformers these facts should be remem­ bered: if iron core type are selected then some wave length between 3,000 and 6,000 should be decided upon and those transformers having that particular funda­ mental wave length should be selected. If, on the other hanrL air core type is to be used, then those having any funda­ mental wave length · between 3,000 and 10.000 meters should be selected, but whatever wave length is chosen, all of the transformers used must be the same. The Function of the Oscillator The next thing to be considered is just how the different incoming waves are changed to meet the requirements of the radio frequency transformers used. This ;s accomplished by the heterodyne method, ,,,hich consists or leading the incoming wave through what is known as the pickup coil, which is inductively connected to a coil in the circuit of the local oscillator. Now then, we have the incoming wave passing through the pickup coil, let us say for example that it is a 360 meter wave. Di"iding 300,000.000 (the speed at which electricity travels) by 360 we obtain the + Q. frequency of this wave. This gives us then a f"equency of 833,000 cycles passing - through the pickup coil (see Figure 1). - N ow if we start the oscillator. the coil of - which is inductively connected to the ""iiiiii"- pickup coil, we will find that another oscil­ --- lating current is induced in the pickup coil, and this current will of course have ,\hatever frequency the oscillator is ad­ justed for. Thus we fmd the pickup coil receiving waves of two frequencies, one of which is the 833.000 cycles from the broadcast station and the other is of some other frequency supplied by the oscillator. These two frequencies, acting upon the pickup coil, will combine, producing a fre-· quency which is equal to the difference between the two. If then we adjust the condensers of the oscillator circuit so that it ,vill have a frequency of 883,000 cycles (340 meters) then the difference between this frequency and that of the incoming wave (833,000 cycles, or 360 meters) will be 50,000 cycles. or a wave length of 6 000 meters. which will be exactly right f~r radio frequency transformers having a wave length of 6,000 meters. The same result will occur if the oscil­ lator is adjusted to produce 783,000 RADIO AGE for June, 1924 The J11agazine of the Hour 7 cycles, or 383 meters, as the difference between the two will stilI be 50,000 cycles, or 6,000 meters. From this process it will be seen that no matter what the fundamental wave length of the radio frequency transform­ ers may be, or what the length of the incoming wave may be, it is possible, by the adjustment of the freql1ency of the local oscillator, to form a combination frequency which will be suitable for the particular radio frequency transformers used. In this way then it is possible to use radio frequency transformers which respond perfectly to only one particular frequency, and by means of the oscillator to change any incoming wave to this fre­ quency. Thus it is possible to get the maximum efficiency from these transform­ ets, no matter what may be the length of the incoming wave. There are several different methods of constructing an oscillator and there are also many different ways of connecting the pickup coil, but as that shown in Figure 1 is found to be very effective, I am using it to show how the oscillator and the radio frequency transformers are con­ nected. Construction of the Oscillator One of the greatest difficulties encoun­ tered in the construction of the super­ heterodyne receiver is to get an oscillator which will oscillate freely over a wide band of wave lengths, and 'much of the trouble experienced in the construction of a set of this kind is caused by a poor oscillator. In cases where the intermedi­ Kadel & Herbert Pboto. ate frequency (that of the radio frequency ENTERTAINMENT WHILE YOU WORK transformers) is set at 3,000 meters, the oscillator should be designed to cover a That's the idea of "Blind George" Wittenberg, newsdealer at Forty-second range of from 214 to 750 meters. Street and Sixtieth Avenue New York City. He combines his business with This will require a variable condenser pleasure by listening to se;ious discourses while he waits upon hi~ customers. And although George is blind he can still see the advantages of havmg RADIO having a capacity of .00083 to .001 M.F. AGE within easy reach on his stand. connected across an inductance of 155 microhenries. For intermediate wave length of 6,000 meters, the oscillator will De Forest Wins Radio Fight awarded priority to the invention to Arm­ have to cover a range of from 207 to strong. Dr. Lee D e Forest, eminent sc ientist 666 meters, which wiII require a variable "The whole c~ase , " says the decision, condenser ranging from .00097 to .001 and "daddy of the radio," was declared "turns upon the question of priority to be M.F. in combination with an inductance to be the originator and sole inventor of determined solely as a question of fact. of 124 microhenries. the "feed back" and regenerative circuits The Commissioner of Patents, affirming Where intermediate wave length of in a ruling handed down recently by the a dec ision by the Board of Examiners-in­ 10,000 meters is to be used, the variable United States Court of Appeals in the Chief. awarded priority to Armstrong. condenser should have a range of from District of Columbia. "We have no doubt but what Armstrong .0001 to .001 M.F. and the inductance The decision. rendered by Chief Justice produced the invention at the time should be 110 microhenries. Most any Smyth, with the associate justices con­ alleged. But his earliest claim to a con­ of the capacities mentioned may be ob­ curring, ends litigation and innumerable ception of his invention in October, 1912, tained with a good 43 plate variable suits which have dragged through the followed by a witnessed sketch on Janu­ vernier condenser and means for obtain­ courts for more than seven years. Because ary 31. 1913, This date gntedates any ing the proper inductance wiII be explained of their importance the suits have at­ time claimed by or available to either later. tracted world-wide attention. Meiss ner or Langmuir and therefore elim­ These values are found mathematically. Four Claimed Invention inates them from further consideratioll. For example, the 3,000 intermediate fre­ Four men, each claiming the invention, Notes Reveal Discovery quency requires wave lengths ranging from ,,'ere directly interested and entangled in "It is clearly shown that De Forest 214 to' 750 meters. The 214 meter wave the suits. They are Doctor D e Forest, in­ was developing the idea involved in this has a frequency of 1,400,000 cycles and ventor of the audion; Dr. Irving Lang­ invention in the early part of 1Q 12. It the 3,000 meter wave (the intermediate) muir, of the General Electric Company; appears from his book-notes that the fir st has a frequency of 100,000 cycles. Sub­ Dr. A. Meissner. German radio expert, discovery of the feed-back circuit oc­ tracting this 100,000 from 1.500,000, and Maj. Edwin H. Armstrong. Five curred in connection with hi s work on the which is the frequency of a 200 meter separate actions with each of these men amplifi er. wave and is the lowest used, we get either ac; defendants or plaintiffs were "There is some testimony prior to 1,400,000 cycles. which is a wave length directly disposed of by the decision. August, 1912, that the oscillating prop­ of 214 meters, which is found by dividing The case which brought the final de­ ertiec; of the audion were discovered by 300.000.000 (the speed of electricity) by cision was brought by Doctors De Forest, D e Forest. The decisions of the Commis­ 1,400,000. The high wave length range Langmuir and M~issner from the decision sioner are reversed aDd a priority awarded (Continued on page 36) of the Commissioner of Patents, who had to De Forest." RADIO AGE for June, 1924 The ~Ma gazi ne of the HO llr Automatic Filament Control By ROSCOE BUNDY

ONTROL of the filament current Individual control of the tubes is desirable These are small cartridge like resistance and electron emission by means of only if the control is automatic. units which remind one of the usual tubu­ C a manually operated rheostat is as Still another item in the economical lar grid leak and are mounted on small old as the vacuum tube, and with the operation of the tubes is that of careless­ springclip bases much like the tubular exception of a few minor refinements in ness in handling a manually controlled leak type. One of the Amperites is placed the general design of the rheostat there rheostat, or the use of a battery switch in series with each of the tube filament has been but little attempt at improve­ ii one is installed. On multi-tube sets it lines, just as with the ordinary rheostats, ment in this part of the circuit. This is the common practice to leave the rheo­ and by the properties of the resistance lack of interest in what is really one of stats of the amplifying stages in their llnit the filament current flow is held at the most important functions of the radio normal "on" position after pulling the a constant value regardless of the voltage receh'er seems strange when one consid­ battery switch, and this means that the fi uctuations of the battery. Fully charged ers the dose attention that has been paid filaments will be subjected to an excessiye or discharged, the battery yoltage makes to the development of the other apparatus current flow for several seconds after the no difference in the potential across the used. battery sw itch is again snapped on, for filaments until the battery voltage is The electron ::.tream issuing from the the cold rheostat will not present its fuli finally allowed to drop below the normal heated filament surface is the carrier of resistance until it has been warmed up by voltage rating of the tube. the radio impulses passing through the several seconds of current flow. During Practical tests with these little auto­ tube, and represents the relaying energy lhis time, the filaments receive abuse matic rheostats showed that the tubes supplied by tile local battery. For this which in the co urse of time will make a were held at the proper voltage through reason the amplification of the tube is in marked reduction in their life. Aga in , a wide range of battery charge conditions, rough proportion to the quantity of elec­ we frequently find that the rheostats have and that all of the tubes in the bank were trons emitted by the frlament, and as the been unintentionally turned full on by in­ delivering their maximum output. As an emissio:1 is roughly proportional to the quisitive persons monkeying with the sets, 8dditional advantage, there were no am­ filament temperature it is evident that the and again the tubes receive a jolt when pli fie r rheostat knobs on the panel and the filament current control is of vital im­ the switch is snapped on. wiring was very much simplified. Instead portance. Every tube develops its maxi­ Probably the most noteworthy attempt of fussing around with the rheostat knobs mum economical electron emission at a at automatic filament control for amplifier and lifting the cover of the cabinet to giyen voltage across the filament circuit. tubes is met with in the "Amperites" watch the filaments, one can confine their If this voltage is much exceeded, then wanufactured by the Radia!l Company. attention to the tuning controls. the filament current will cause some ad­ ditional amplification but at the cost of a marked reduction in the use ful life of the tube. With a voltage lower than normal, the emission will be reduced and the amplification will suffe r to a corre­ sponding degree. Unless a voltmeter is attached to each receiving set, as is very frequently done with the large and expensive Super-Hetero­ dynes, it is almost certain that voltage control will be uncertain and that either the life of the tubes or the amplification will be reduced below the normal mark set by the maker of the tubes. Unguided hand control is both wasteful and annoy­ ing in the operation of amplifier tubes. The ideal condition for the operation of amplifier tubes is met with in an automatic device which will maintain the constant rated voltage across the filament regard­ less of fluctuations in the battery voltage, all without the attention of the operator. With the large multi-tube receiving sets of the present day, such as the neutrodyne and Super-Heterodyne, the control of from four to six amplifying tubes is quite a problem. All of the tubes connected in one series must give equal electron emission for maximum amplification and this is hardly possible when the tubes are controlled separately by manually oper­ ated rheostats or even when the bank cf tubes is operated from a single rheostat. Individual regulation depending upon the judgment of the operator is the height of uncertainty. With the tubes operated from a common rheostat, there will be a difference in potential across the filament OFTEN HEARD BUT SELDOM SEEN ".v of each tube due to the voltage drop in These are the "faces that go with the voices" from Station V:/GY, the Schenec- the line, the voltage being lower at the tady station of the General Electric ComP:=tny. The.se popular a!lnouncers are, tube farthest from the rheostat than at from left to right, front row: Robert Weldaw, Kohn Hager, chIef ann0l!ncer; the tube next to the variable resista!1ce. Carl Jester; back row, William Fay, Asa O. Coggeshall and Edward H. SmIth. RADIO AGE for June, 1924 The Jlvfa ga:; ine of the Hour 9 A Universal Atnplifier By FELIX ANDERSON

:I .I t L \) () () () 2 z e: 9 ~'G CI~()(J() e e~ aaaoa (:) () ~ () a ,(>//£0 TAT ~ RHEOSTAT

Figure 3. An isometric sketch of the improved amplifier with wires numbered to correspond with the circuit diagram of Figure 4.

ECENTLY the writer has noted a homes these small compact portable re­ amplifying circuit more commonly known tremendous demand for receivers ceivers will lose their usefulness inasmuch as push-pull amplification. R of the improved type. Readers as their signals are not loud enough to be The merits of using the balanced am­ have repeatedly sent in requests asking used to entertain a large gathering. plifier for a third stage were discussed in how their one-tube receivers may be im­ The writer decided, therefore, that it detail in the January, 1924, number, where proved. In their questions they request would be a good idea to show readers how the separate unit 'of this type was de­ us to specify whether radio frequency or to construct a unit that could be con­ scribed. Briefly, its advantage lies in the audio frequency shall be used, and in nected to either a portable or a home re­ fact that the two tubes are practically some cases both are advised; some only ceiver; and which would produce signals used to do the work of one, which results audio or radio, and some neither. This de­ of sufficient intensity to be used on the in more efficient action on the part of the pends entirely upon the type of circuit same basis as the phonograph; for dancing valves and transformers and produces a used. and general entertainment. signal of great audibility without the cu s­ With the idea in mind of designing a Returning to our original subject, the t omary squeals, distortions and noises unit that could be used effectively on any demand for improvements on receivers which accompany amplifiers in the third type of receiver, the writer decided that has been very great and we therefore rec­ stage when connected in cascade. the majority of the simple circuits would ommend that experimenters who care to The expense involved in such a unit is not profit by a radio frequency amplify­ improve their present sets consider the not very great when one considers the ing unit, and therefore devoted his atten­ construction of a unit of this type. quality, amount, and nature of the signals tion toward designing a unit that would The improved Cockaday is probably produced. be compact, inexpensive, efficient, and the most convinCing argument in this be­ Construction which could be used to advantage with half. The Unit First of all, the parts required for the practically any type of receiver. unit are as follows: The unit which I am about to describe Portables for Vacations consists of two stages of cascade audio panel, 7x14 inches. With the advent of Summer, one also frequency amplification which uses the cabinet, 7x14 inches. has · to consider that there will be many tubes in the ordinary manner of connect­ mounting board. portable sets constructed which will be ing up the two-stage amplifier . .. The re­ taken on vacation journeys and jaunts. maining tubes are used as a third stage (Continued on page 16.) On returning to the summer cottages or of amplification employing the balanced (Diagram s on next page.) 10 RADIO AGE for June, 1924 The lIfagazine of the flour Atnplifying Unit for Any Type of Receiver (C olltinued fro11l precedillg pa ge.)

C,qL , Pr'z ,7 L .z F ,$ , $ '" n.t IJ.Jpur I~ III

7 ~ Ek'6 '8

1Z %1 g ., 12

I~ PP,? 11 IS- .. I, ,S" //, 16

1$ ft ZJ iJ '9 Z:I 23 fz 23 tJ Z3 ZiI I') g ., ltJ'2l ' 8 '", '9 ~ A+ A- t' ? ~ :J ,"1 Z3 INwr Il/I 11 + C 11 21 -;;1 - Figure 4. COJl nections on the above cut correspond with the numbering on Figure J.

VS

Figure 5. A back view of the amplifier described in the text 011 pages 9, 10 and 16. The lettering refers to the followillg parts: PPI and PP2 the push-pull transformers, S 1, 2, 3 and 4 the tube sockets, ] 2 the jack for the cascade amplifiers, CA 1 and 2 the cascade transformers, and the bill ding posts which are marked accordillg to their respective polarities. This unit can be used effectively with any type of receiver, and will deliver signals of great intensity when properly constructed alld operated. Two sets of input binding posts are used, making it possible to use the unit with either right or left handed receivers. (This article continued on page 16.) RADIO AGE for June, 1924 The J.lIagaziile of the 11();.r 11 All Together for a Radio SutnITler 1924 to Be Most Popular Season HE Summer of 1924 is destined to the thunder of applause for popular can­ in popularity radio will enjoy this Sum­ be the greatest "radio Summer" didates-the music, the clamor and the mer. T since broadcasting was begun, as a excitement of the impromptu parades Manufacturers of radio products point result of extensive plans and programs which will spring up from time to time out that because of the vast improvement just completed by leading broadcasting on the convention floors. Elaborate ar­ in radio apparatus during the past year, stations throughout the country, as well rangements are being made so that the the varied programs from many broad­ as manufacturers of radio apparatus. largest possible radio audience may be casting centers will be received with great A nation-wide survey has disclosed that able to listen in on these conventions. satisfaction by millions of radio "fans" at no previous time has the radio industry Immediately after the conventions will throughout the country. been so geared to give a higher standard come the Presidential election campaigns, With 591 broadcasting stations to select of service to the radio public. Reports in which radio again will play an epochal from this Summer, no town or hamlet in from manufacturers, distributors, ama­ part, for nearly every candidate intends to the country will be without a suitable pro­ teurs' organizations and other factors in broadcast his appeal to the electorate gram during the sultry days. Changes in the industry indicate a general movement through the air. antenna and aerial systems have increased to bring radio out into the sunshine during the radiation efficiency of many stations. the Summer months. Increase In "B" Stations Because there are more Class B high­ Broadcasters to Join Conventions "On Air" powered broadcasting stations in opera­ Probably the great Summer-time event tion this year than during 1923, reception The broadcasters especially are doing on the season's schedule is the Democratic during the hottest Summer months will their "bit" to make 1924 a successful radio national conventi0n in New York City this be vastly better than ever before. The Summer. Inter-connecting systems of month and the Republican national con­ new allocation of wave lengths, especially radio broadcasting, whereby important vention in Cleveland. These great gather­ among the higher powered stations. is ex­ stations will join for the simultaneous ings will put the "fan" in the thick of the pected to eliminate much of the interfer­ broadcasting of outstanding events, will pre-election campaign and for the nrst ence resulting from conflicting wave insure the clear and adequate reception time in history millions of people will be lengths. of the many messages of national import­ able to "attend" the national conventions. Most of the great sporting classics and ance now being planned. The listeners-in will be able to follow outdoor events scheduled for 1924 will be The uses of radio during Summer-time each political issue as it -is fought out on held during day-time, thus assuring clarity are unlimited. Besides being a fascinating the convention floor; they will hear. the of reception. Also, such events offer an­ pastime during the long Winter months, nomination speeches of "favorite sons"; other reason for the anticipated increase radio reception will be a boon to those

Kadel & H erbert Photo. NOW A FLAT TIRE IS A PLEASURE For while she's waiting for someone to come along and ch ange the tire, our lady vacationist can tune in on her faithful set and be entertained from distant cities. Radio has become so popular that vacationists and tourists this year are plan­ ning to take their sets along to help idle away the Summer hours. The scene above was snapped in the vicinity of Wash­ ington, D. C., and shows a radio enthusiast experimenting wit h a super-heterodyne with which no aerial or ground is needed. 12 RADIO AGEJor June, 1924 The Magazine oj the Hour who have vacation thoughts for Summer. Radio Conference Planned although wave lengths available for this Radio can be quickly made a permanent use are practically exhausted and stations part of every seashore home ; the moun­ Secretary of Commerce Hoover will call are doubling up. Even time allotments tain home or lodge; the camp; the auto­ a general radio conference in \Vashington in congested sections are becoming diffi­ mobile on tour ; the farm catering to soon after the adjournment of Congress cult to make. Summer boarders and the motor boat or in an effort to secure co-operation of all Secretary Hoover believes congested canoe with fa cilities for a portable receiv­ radio interests in clearing up the 'ether conditions and interference are not im­ ing set. and solving the problem of distributing proving. Any of these places can easily be wave lengths. A conference will be called If the White bill is enacted, Secretary equipped with a radio set, for they are whether or not new legislation is enacted. Hoover pointed out, new regulations and never so far away from the nearest broad­ The conference will be similar to those probably re-allocations of wave lengths casting station that good results cannot be in the Springs of 1922 and 1923 , at which will have to be made, and if no legislatioil obtained. Portable sets, which can be representatives of the manufacturers, is passed this will still be the case; other­ transported from place to place and set broadcasters, engineers, amateurs, com­ wise a c'ondition such as prevailed two up in a few moments, are expected to be mercial operators, and broadcast listeners years ago would confront the radio public. extraordinarily popular this Summer. aided in drawing up voluntary regulations under which radio has been supervised Thousands in "Radio Church" Radio Everywhere ever since. It was in this manner that Summer resorts already are adve rtising The voices of clergymen in Schenectady, the distribution of wave lengths for broad­ X. Y., which for years have been limited radio as one of their special advantages casters and other interests was developed. for the vacation months. All this fore­ to the confines of their churches, are now Present indications are that broadcast­ cast of expected conditions indicates that carried to all parts of the North Ameri­ ing stations will continue to increase. no matter where a " fan" travels this year, can continent by radio. he can always have his faithful friend, radio, within easy reach. The baseball fan will be able to follow his favorite team no matter where he goes. Every station of importance is arranging to broadcast the baseball scores in all the leagues. Several boxing events, ending with a championship bout between Jack Dempsey and Harry Wills in the late Sum­ mer, will be carried through the ether to millions of eager listeners. A comprehensive list of suggestions for the summer-time radio fan, with latest pictures and diagrams, will be published in the RADIO AGE for July. Watch for it.

Every Sunday the services of the many churches in Schenectady are attended by two congregations; one visible to the pas­ tor and the other that unseen but apprecia­ tive audience of radio devotees. Sermons Go Everywhere Religious services have been a regular part of \YGY's programs for several months, in co-operation with the Sche­ nectady Ministerial Association. The messages of the clergy have reached espe­ cially to the thinly populated districts of Northern New York, New Hampshire, Vermont and Canada. Kadel & Herbert Pho to, All of the ministers report the daily BROADCASTING FROM THE CLOUDS receipt of letters of appreciation from the listeners. Frequently they contain sums The newest feature of broadcasting has been adopted by army fliers. Under of money" which in many cases are set the direction of Major George Vaughn, 27th Air Service of the New York National aside as mission funds. The most en­ Guard, former aces are now piloting airplanes and broadcasting interesting talks on army life while their machines speed through the sky. Each radio plane covers thusiastic praise has been received from a specified territory and is equipped with a five-tube army transmitting set, which woodsmen, farmers, forest rangers, keep­ makes the new innovation possible. The picture shows Captain Brower. former war ers of light Ehips and others in isolated ace, piloting a Curtis plane while a radio engineer is talking into the transmitter. regions. RADIO AGEjor June, 1924 The Magazine oj the Hour 13 A Sure Fire Reflex Set By R. J. ROBBINS

T HAS been my sad experience · that The same procedure is carried out in mounted by means of long 8-32 flathead there are many so-called reflex hook­ regard to the shelf, which is shown in brass machine screws and check nuts in I ups printed for which great claims Fig. 4. If other parts than those specified such manner that it is s;:,-aced back from were made. The ones which intrigued my are to be substituted some of these figures the panel about 0 inch. If this combina­ interest mostly, however, were the one­ wili probably have to be altered, but this tion is used a very efficient tuning unit is tube sets which were widely advertised is left to the individual who builds the assured and the front appearance will be to wor~ a loud speaker, but which I, set. In the case of the Acme R. F. trans­ found to be quite effective. It will be frankly, have not been able to duplicate in former substitution is not advised, as a noted that the edge of dial comes directly practice. At the beginning of this descrip­ great .leal of the success of the set will in line with one of the mounting screws tion of my latest pet circuit I will be par­ depend on this feature alone. . which support the shelf. This was inten­ doned if I remark that this set will not tional design and offers a very handy index work a loud speaker in my town on any­ Assembly of the Set f or the dial if the slot in the screw is left thing except the local broadcaster. N ever­ The use of the neutroformer provides in a vertical position to line up properly the!ess, it will satisfy the most hardened a novel tuner which has thus far proved with the dial divisions. BCL for tone quality, distance and vol­ very satisfactory. The aperiodic primary The rheostat, potentiometer, jack, an­ ume. The circuit used is an old standby winding eliminates the necessity for tenna and ground binding posts are now that is known to every BCL or Ham and switches and taps in the antenna circuit, put in place, particular care being taken was selected from several as the most thereby boiling down the total adjustments in the case of the first two named that promising of all. The general layout and of the set to four-if the crystal detector binding posts face upward. The potenti­ method of tuning may be of interest, and may be classed thus. ometer should be on the side facing the it is hoped that a few of the DT's will The shelf is first mounted in place by ground lead, thus insuring short connec­ try it out. I can promise entire satisfac· means of the 7-inch length of angle brass tions. The crystal detector occupies the tion if all instructions are faithfully car· drilled oif as shown in FiJi.. 5 and held to space to the right of the dial in the two ried out. the front panel and shelf by means of holes provided for it. This completes flathead brass 8-32 machine screws and the assembly of the panel. Materials Needed nuts. The balance of the work is soon accom­ panel condensite celoron or radion, The neutroformer comes next. being plished. The socket is mounted in the lOxlOx~6 inches. panel for shelf celoron or radion, 8xS 0X~6 inches. 1 potentiometer, 400 ohms. 1 rheostat, 30 ohms. 1 good socket (do not substitute). 1 neutroformer. 1 4-inch dial. 1 piece angle brass, 0x0 x7 inches. 1 jack (double circuit if audio am- plifier to be used. 1 crystal detector. 1 audio transformer. 1 Acme R-2 R. F. transformer. 4 binding posts. 3 mica fixed condensers, .002, .006, .001 M. F. Layout of the Panel and Shelf The dimensions given for the panel and shelf are not in conformity with the standard sizes now furnished by most manufacturers, although the writer knows of at least one who carried the lOxIO-inch size fairly recently. The layout for the panel with all nece:>sary dimensions and indications of operations to be performed is shown in Fig. 3, while Figs. 1 and 2 rep­ resent the front and rear views, respec­ tively, of the assembled set. The various holes are first laid out care­ fully. The only part of the work which should present any difficulty will be the sight holes for the bulb and the mounting screws for the neutroformer. The centers for all of these holes should all be located carefully by means of the compasses and all intersections of lines at correct points should then be deeply punched to center the drill. Figure 1. A jront panel elevation oj the Simple Sure Fire R eflex R eceiver. There All holes should be started with a small are only three major controls, two oj which require but little attention while tUllin g. size drill to insure accuracy. These are The dial in the upper lejt-hand comer is the potentiometer, immediately to the right then "chased" with increasingly larger are the peep .':oles jor the tube, and next is the rheostat. Directly below the poten­ sizes until all are of the sizes specified in tiometer is the tuning condenser and to the right is the crystal detector. A phone plan. jack is shown directly to the right and above the crystal detector. 14 RADIO AGE for June, 1924 The ~Magazille of the !Iour

center of the shelf in the position shown. Care should be taken that the posts marked G and P be left facing the rear, which will make for the shortest possible leads. The R. F. transformer is then put in place to the left of the socket and the audio transformer to the right. This places it close to the grid, which is de­ sirable, while the plate leads are equally short to the R. F. transformer and B battery posts. The binding posts are the last to be put in place. This completes the assembly work on the set, and we are ready to commence the last stage of the work, namely, the wiring. To some this work is the bugaboo of making a set, but there are compara­ tively few wires in this set, and this should present little difficulty even to an inex­ perienced worker.

Wiring of the Reflex The writer may horrify certain of the radio fraternity who have fixed ideas as regards methods of wiring and soldering connections. The first blow will be dealt to those who use rosin. Manv use this stuff and apparently get away \~ith it, but here is one experienced radio man who says that the stuff is better to oil up fiddle bows with. The tinsmith doubtless will find it very serviceable in his profession, but it is not good for this work. I just had the pleasure of tearing down a per­ fectly nice job which had been done on a five-tube N eutrodyne which refused to utter a whimper. The root of the troub!e proved to be the nOll-corrosive rosin which Figure 2. The back panel layout of the simple Sure Fire Reflex Receiver. occupied every bit of space it could find in the interstices between the soldering lugs and binding posts. This formed a nicely illsulated joint which would not pass storage battery current in some cases. In passing may I mention that I do not use an excessive amount of flux or solder on any joint, yet the above trouble de­ veloped after conside rable precaution had been exercised. The cure was found in the use of muriatic acid cut with zinc and used very sparingly with plenty of heat to each joint. Do not be content until the solder runs bright and flows evenly o\'er the wire. In the case of binding posts it will be found more effective not to use soldering lugs at all, but make connections direct with the wire itself by making neat bends in it with the pliers and gripping with the posts. Do not solder to a post, as this procedure is unnecessary and makes dis­ sembling of the set more difficult if this should prove necessary. Keep all wiring widely spaced and run plate and grid wires at right angles if any come near each other. Try to figure the shortest possible route for each wire to run and keep all lines parallel by making neat bends of 90 degrees whenever a wire has to change direction. After wire is all in place connect in the three fixed condensers at points indicated and set is ready to try out. At this time it would be well to provide a suitable cabinet. This may be of oak, mahogany, birch or any 5" 1" ,.0 ," ,tt wood preferred by the builder and should (3 ---1-8 Z-z Z-z ----'----Z-z be given a good finish, as the set will pre­ Figure 3. Template, drilling and layout instructions for the simple reflex described sent a fine appearance if properly en­ in the accompanying article. closed. RADIO AGE for June, 1924 The Magazine of the Hour 15 Some Hints for Operating -...... ,.-- --...---Z,"------. This set will be found to give best re­ sults with UV20lA tubes, although the UV199's may be used if the proper socket is used originally. Do not use adapters, +-~--~-+--+--- H-- as too much energy is lost in these make­ shift arrangements. Short, direct leads and good connections go far to insure suc­ cess with a reflex set. Insulation is of paramount importance and the writer ad­ +-1.! _i vises against anything but a solid rubber socket or one made entirely of bakelite or similar material. This feature alone ! has spelled doom to success for many. ~~ ~X~. t- +- tt Those with metal ferrules especialiy are to be avoided, as undesirable capacity -.--+ --·~~~-L±=r~----f--, effects are too often introduced in such sockets. Quite often we hear of seme person who has a set employing one or i ".~)~ +-'Ir-~ two stages of R, F. amplification bulb cletector and additional tubes for audio. l DR/II holes fl .R 50Gtet SCRews f I He employs sockets such as were men­ T ' All OHI~S IIsrJ D~i'/. tioned above and very often finds that his bulb detector will rectify perfectly with­ out grid condenser or leak. As a matter _ .-t-- ---+------t--~MIQ) of fact, the poor· insulation between ter­ minals is responsible for these results in a great many cases and his tube is no dif­ I-f--'---I-{ ---t--- /-f' -.,...... -1-1.. J-­ ferent from scores of others which ordi­ ---~--- z- {' ---.L..--- /- {' narily perform in normal style. For a set /-·f-...... --- z-·f of this kind the oft despised porcelain Figure 4. H ow to drill the holes on the tube and transformer shelf. sockets which have been placed on the market by several courageous manufac­ 'turers should yield very good results and .--____ Z;.ill Z-.l 1/ __~-. may be classed favorably with the all-rub­ ber or all-bakelite sockets mentioned be­ fore. When all is ready connect the A and B batteries to the proper binding posts and light the bulb by turning up the rheostat. A pronounced click in the phones should be heard when the plug is pushed into the jack, indicating that the plate circuit has been connected up correctly. If there is no stray leakage at any point no music, signals or noises of any kind should be audible until the catwhisker is placed upon a sensitive point on the crystal. It will Figure 5. The bracket supporting the shelf is drilled in the 111mmer shown here­ be found very simple to locate a good with for the best mounting arrangemellt.

spot, as the crystal is very easy to operate when strong R. F. voltages are applied to it. Any good crystal rectifier such as galena, radiocite, silicon or carborundum will be satisfactory. Their grade of sensi­ tiveness will be about in the order named. When a broadcasting station is tuned in on the dial the potentiometer and rheo­ stat are given further adjustments until the signal is at maximum intensity. It may be well to try for a better point on the crystal also as this will make a marked difference on the strength of the received music. Several bulbs should be tried out until a good one is found, as all 20lA's will not reflex equally well. In the writer's experiments a 5-watt power tube gave surprising results on a 6-volt A battery and 90-volts plate which is far below the rated plate voltage for these tubes. It is suggested that this set by a little alteration in design may be adapted to a portable form including batteries and all by use of the UV199 tubes. I n such case the panel may be made a little smaller. T he rheostat and potentiometer would

Figure 6. A top elevation of the Sure Fire Reflex. (Co1lti1lued 0 11 pa ge 26.) 16 RADIO AGEJor June, 1924 The J1;[agazine oj the Hour

RHEOSTAT RHEOSTAT Figure 2. A top view showing the layout of apparatus and their respective mounting on the panel. Binding posts make connections with the wires going to the batteries through holes drilled in the back of the panel. The cabinet should be one with a hinged top.

A Universal Amplifier they should provide sufficient resistance and 3, double and single circuit jacks re­ for the two tubes when used in parallel. spectively, binding posts being lettered in (Contillued from pa ge 10,) If the type of rheostats shown are used, accordance with their respective values. the connections should be made in accord­ It is a wise plan if the set is found to 2 rheostats, 6: 10 ohms. ance with instructions accompanying be noisy to place a .00025 MF fixed mica 1 5-to-1 amplifying transformer. them. The jack, J1, connects to the plate condenser across the secondary (G and F 1 3-to-1 amplifying transformer. circuit and B battery of the detector, and posts) on the cascade transformers and 1 pair push-pull transformers. provides a means of using the detector across this condenser connect a grid leak 4 tube sockets. alone if so desired. of the pencil mark type. This invariably 2 four-spring jacks. When the plug is inserted in J2 and the reduces noises and clears up reception. 1 2-spring jack. first rheostat is turned on, the cascade 6 Fahnestock binding posts. amplifiers are in use. When the second The signals can be adjusted further by 4 panel mounting binding posts. rheostat is turned on and the phones placing the .low ratio transformer in the· 7 small wood screws. plugged into J3, the balanced amplifier is first cascade amplifi er circuit. and by 20 feet tinned copper busbar. automatically connecLed into the circuit shunting a .001 MF fixed condenser acrOSS 4 UV 201-A tubes. and the entire component is used. the input posts on the paneL 1 nine-volt C battery. The writer is aware of the fact that 2 forty-fi\'e-volt block batteries. there are many receivers built with both right and left hand outputs, and has there­ The panel should be drilled in accord­ fore incorporated the idea of two input ance with Figure 5, which shows the back sets of binding posts on the front of the view of the unit. It is quite necessary to panel. This is a matter left to the judg­ The RADIO AGE data adhere to this method of drilling if the ment of the builder, who can decide which sheets printed on pages layo ut of apparatus shown in Figure 2 is is the most efficient from the construction to be used. of his present set. 3'7 and 39 should be care­ Two Rheostats Used Figures 3 and 4 are the working sketch fully fil ed away as de­ The apparatus should be placed as and wiring diagrams respectively. The scribed in the preceding ~hown in Figure 2. It will be noted that wi res are numbered to correspond to re­ this affords short connections; it places duce the possibility of incorrect connec­ Issue. all transformers with cores at right angles, tions. thereby reducing chance of interstage Figure 5 is another view of the unit, Tn a comparatively short coupling, and yet preserves the symmetry showing how the arrangement looks from t i 111 e these sheets will of the unit so that the tube sockets wi ll a rear elevation. come directly behind the peep holes drilled represent a world of valu­ in the panel. Getting Rid of Noise able information and ref­ Only two rheostats are used, one con­ In all cases the lettering refers to the erence. trolling the cascade amplifiers, and the fo llowing parts. CA 1 is the first cascade remaining one controlling the balanced transformer; CA2 the second; PP1 and Don't fail to save them. amplifier. Rheostats should be from 6 to PP2 are the push-pull transformers; SI, 10 ohms if UV 201-A tubes are used, and 2, 3, and 4, the tubes and sockets; Jl, 2, RADIQ AGE for June, 1924 1 he Magazine of the Hour 17 Broadcaster Wins Copyright Suit

NE of the most important court whether copyrighted or not, without their part of the broadcasters, and the wishes decisions in the history of radio \vas being compelled to pay a special tax to of the society were complied with. Some O handed down in the United States the American Society of Composers, time later the society notified all broad­ District Court at Cincinnati, when Judge Authors and Publishers, of which the casting stations that they must pay a spe­ Smith Hickenlooper ruled that radio is not Remick Company is a member. cial tax to the society be(ore they could a public performance for profit and the The Crosley company's attorneys' sole play copyrighted music. There were a broadcasting of copyrighted music does contention was that the broadcasting of a number of station owners who agreed to not constitute a violation of the copyright song is not a public performance f01" the request of the society and paid this laws. profit. tax, but there were others, including the Accordingly Judge Hickenlooper dis­ Crosley Radio Corporation, who con­ missed a suit filed by Jerome R Remick History of Campaign tended the imposition of this tax was un­ & Company, Inc., New York music pub­ The campaign against broadcasting sta­ constitutional and refused to pay it. A lishers, against the Crosley Radio Cor­ tions was started by certain members of large amount of music was being pub­ poration, in which the plaintiffs attempted the American Society of Song Writers, lished by independent music houses, and to compel the Crosley Corporation to pay Authors and Publishers, about two years distributed among the radio stations by a special tax for permission fo broadcast ago. They began by notifying the studio the National Association of Broadcasters, copyrighted music. directors that they could not play certain and from this the radio stations selected music unless they announced before each their songs. Not For Profit selection that it was being played by per­ The task of eliminating all copyrighted The rendition of a copyright musical mission of the society. music, however, was a fairly large one, composition is not a "public performance" There was no objection to this on the and due to an error a copyrighted selection within the meaning of the music copyright law, the judge explained, because in mak­ ing the copyright statutes Congress in- 1ended that there must be an assemblage of persons congregated at the place of amusement for the purpose of hearing the music. The Remick petition was dismissed on the grounds that the facts stated did not establish just cause for action. The decision will have an important Learing on the radio industry and the de­ velopment of broadcasting, as it literally makes the air free for radio. It gives broadcasters the right to play all music,

was played from W L W. This happened to be a song published by the Remick Company, and so that organization filed the suit. The latest decision regarding broadcast­ ing of copyrighted music wiII be appealed and probably will go to the United States Supreme Court, unless the National As­ sociation of Broadcasters succeeds in hav­ ing the Copyright Act amended. The Association of Broadcasters, how- ;;;;;=;;;;1e ver, h a~ warned its members against using American Society music, on the basis of the decision, because broadcasters must remember that this is a decision io::::;.....J~~~L.!!...... !J merely by a single judge, and that judge himself is of the view that his decision is Photo Topics. Illc contrary to that of another Federal judge. THE LINE FORMS ON THE RIGHT If the highest court reverses this decision, then various penalties for infringement When the New Y ork Police Department placed a ban on loud speakers in front would be enforced. Broadcasters are of stores, the Chamberlain Electric Company showed a bit of enterprise to gain the attention of passers-by, They hitched up a few sets of earphones to a set therefore advised to avoid using any displayed in the window, and offered them to pedestrians who cared to listen in. music except that which is released and The number of persons who stand in front of the window was limited, but the approved by the National Association of "fans" waited in line to get a few bits of a popular concert. Broadcasters. 18 RADIO AGE for June, 1924 The ~Magazine of the Hour Amendment In Senate Whether copyright laws will apply to compositions broadcast in the ether, re­ quiring payments of royalties to the authors, composers and publishers by the broadcasting stations, is now up to the Senate Patent Committee. Considering the mass of testimony, pro and con, given in two days of hearing on the amendment to the Copyright Laws proposed by Sen­ ator c. C. Dill, which would eliminate broadcasters from paying fees to copy­ right holders, it may be some time before the committee can digest the matter and make a report _ "Like free speech, religion and the free­ dom of the press, he wants radio un-han­ dicapped and un-controlled," Senator Dill said. "If moving pictures and automo­ biles took their people out of their homes, radio has a tendency to bring them back. The listener-in should not be taxed, and he is confident that through radio a universal language will develop which will better unite people of all nations, and may pre­ vent future wars." Opposition to his measure, The Dill Bill, S2600, is strong, however, and Se n­ ator Dill's plans may be defeated in com­ mittee or later on the floor. Leading musicians, authors, composers and publishers appeared before the Sen­ ate Committee, in opposition to the Dill Bill. In general they were members of the American Society of Composers, Authors and Publishers, but some inde­ pendents also testified. Those present included Gene Buck, president of the society; Victor Herbert, vice-president; E. C. Mills, chairman of the administrative -committee; Ellis Bar­ ker Butler, president of the Authors' League; John Philip Sousa, Augustus Thomas, and Nathan Burkam, attorney for the Composers' Society. Kadel & H erbert Photo. Mr. Buck said he was appearing in op­ SECRETARY HUGHES OPENS CONVENTION position to the Dill Bill "for the life of song writing," and flatly denied that the Charles Evans Hughes, secretary of state, made an impressive keynote speech Publishers' Association was a monopoly before the Republican State Convention in New York recently; doubly impressive or trust of any kind. Questioned, Mr. because his message was broadcast to eager partisans who could not attend the Buck answered that the association, in convention. Here he is before the microphone, addressing the convention and asking broadcasters to pay for using his ethereal audience. songs, does not differentiate between a station operated by a radio manufacturer songs which they send out. He believes shore lines so they could not be recognized. or one operated by a newspaper. He con­ t hat the music publisher is opposing the Calling his radio compass into service, he tended that when people hea r a song over bill and not the writers and authors. took radio bearings from North Sydney, the radio they do not care to buy it and Magdalen Island, and Canso, with the re­ said that the continual use of a song in Drake Takes Over WDAP sult that he succeeded in locating his posi­ the air made the people "sick of it." Arrangements were completed last week tion. Herbert and Sousa Oppose whereby The Drake Hotel, Chicago, is to Endeavoring to find the proper point assume permanent control of Station at which to land in a fog, Captain Bauge Victor Herbert and John Philip Sousa WDAP, formerly owned by The Chicago and a native fisherman who was on board also opposed the bill, contending that the Board of Trade. While the broadcasting were greatly confused by a mirage which present copyright law should not be of market reports is expected to be con­ changed the appearance of the coast. changed. tinued, the new owners ha\'e announced They knew they were not in front of Charles H. Tuttle, of the National As­ they will reorganize the operation of the Scarati, for a steep cliff could be seen sociation of Broadcasters, stated that station and possibly apply for a new wave behind the lighthouse, obviously not the radio was the greatest blessing that science length. The ca ll letters also may be gentle sloping hill of the Nova Scotia ever had given to man. He accused the changed. Jack Nelson, who has bee n shore, five miles distant from the light­ composers of "passing the buck" to the director of the station for several months, house. listener-in and claimed that the compos­ will continue in that capacity. An exten­ Standing by temporarily until the sun ers wanted the broadcasters to join with sive series of interesting programs is being came out, the skipper took an altitude, them in an agreement to charge the pub­ arranged for June, it was said. which plotted with his radio bearings, in­ lic, in which case it would be one of the tersected in a triangle of error of less than greatest monopolies ever realized. He Radio Helps Solve Mirage three miles on a side. He was east-north­ rip.nied that radio was emptying the mov­ When approaching Sydney, Nova east of Scarati. Soon the lighthouse ap­ ing picture houses. The Composers' As­ Scotia, recently, Captain Bauge of the peared in its natural place. The radio sociation was said to be trying to tax the Hospital Ship St. Joan of Arc, was con­ compass proved correct, he states, despite radio broadcasters and not the individual fronted by a mirage which distorted the the "evidence" of their eyes. RADIO AGEjor June, 1924 Tlze AIaga;:;ine oj the Hour 19 The Why of the Heterodyne By JOHN B. RATHBUN

P TO the present time, nearly every Amplification Wavelength Differs amplification of the waves. With circuits article published on the subject of amplifying at varying broadcasting fre­ U the super-heterodyne has started To begin with we must understand that quencies, it is not likely that we much out in the same way, and after reading our the super-heterodyne is essentially a radio exceed 60 per cent of the full amplifica­ first article on the subject we can gen­ frequency amplification circuit, and in tion capacity of the tubes because of cer­ erally omit the first page and a half of many ways comparable with the standard tain reactions that take' place in both the each succeeding article with perfect safety. R. F. circuits or the well-known neutro­ tubes and the transformers. Possibly this is perfectly correct for arti­ dyne. The incoming waves are first am­ As with all radio frequency circuits we cles dealing with so novel a principle, but plified before the final detection and reduc­ have the regeneration or feed-back to con­ at times it is rather a bore to read the tion to audible waves which affect the tend with that is due to the capacitance constant reiteration on the theory of beat diaphragms of the phones or loud speaker. or condenser effect between the grid and reception or how two superimposed waves The outstanding difference lies in the fact plate of the tube. The grid and the plate of different frequencies lead to a resultant that the radio frequency waves in the (in effect) form the two plates of an elec­ wave of a different frequency or wave heterodyne are amplified at a constant trical condenser and through the capaci­ length. In view of all this repetition on frequency under all conditions and' not at tance of this small condenser, energy is the development of the long wave or beat any old wave length that the set may fed back into the grid circuit from the note, it seems exceedingly strange that all happen to be tuned in on. Both the stand­ plate circuit, thus introducing oscillations of the writers gracefully side step the true ard radio frequency sets and the neutro­ and other reactions which interfere seri­ purpose of all this elaborate preparation dyne carryon amplification at the ously with amplification of the radio fre­ and entirely fail in telling us why amplifi­ broadcasting wave lengths of the various quency circuit. An interchange of electri­ cation at radio frequencies is more efficient stations, but the super-heterodyne am­ cal charges also takes place in the reverse on long wave lengths than at broadcasting plifies at one constant wave length regard­ direction, from the grid to plate, so that frequencies. less of the station wave length. a certain percentage of the grid charges In this little sketch I am going to depart are dissipated to the plate and hence the somewhat from the conventional and at­ Advantages control of the grid over the electron tempt to short description of what takes It has been intimated in the 101 articles stream is reduced. The net result of the place in the intermediate stages after the on the subject already printed that am­ grid-plate capacity is reduced amplifica­ broadcasting waves have passed through plification at a constant long wave length tion and range. the frequency changing stage of the cir­ greatly increases the effectiveness of the In the neutrodyne circuit, the capaci­ cuit. We will therefore assume that the radio frequency amplifying stages. It per­ tance or condenser effect between the grid long wave resultant has already been cre­ mits of a degree of amplification not and plate of the tube is "neutralized" by ated in the oscillator-tuner stage by some approached by the standard radio fre­ the introduction of small condensers means or other, and that the low fre­ quency circuits or by even the neutrodyne. known as "neutrodons" so that there is quency wave has just entered the first The whole circuit, transformers, tubes and little feed-back or regeneration between stage of the radio frequency amplification all, can be adjusted to their most advan­ the radio stages. The reactance of the system, where it is to be amplified before tageous frequency and then afterwards neutrodons opposes the reactance of the entering the second detector tube for re­ operated indefinitely at this optimum wave grid-plate condenser, and hence is a de­ duction to audio frequency. Whether this length. By this means we can more nearly cided step in advance of the standard radio long wave has been created by the super­ approach the full output capacity of the frequency circuit. However, perfect neu­ imposed oscillations of a tube or by those tubes than by any other method yet pro­ tralizing adjustment is seldom attained of a motor-generator is no concern of ours posed, and as we all know, the capacity under practical working conditions, and at the present. of the tubes is the limiting factor in the many of the evils attending amplification

IMPROVED SUPER-HETERODYN~ CIRCUIT

/It-8- +90V /1- /1-/-2'3-4-5-6-7-8 TII/Jf SO{lffTJ.- c-6 01111 RHf05TAT-. it-WIll {tJirO£N-1£H.0005I1t-L -f/LiMfIVT 5W/T{/I f3-h?-.3-4 INTfIlMff)I/lTlIWf()tJfN{Y TlfIJIIJrtJI?I'!fI?5 - J- VIIR (ONDfN5fR.OOll1t-l1-rlX.((W/J. OOINt C -h? /lUf)/O rl?f"OUfN{Y TI?AN5FOl?l1fR5-r -POTfNT/ONflfl?1-00'OIlN- J- PI/O,A/! J//{K-N-rlA. (ONf) 2M! /)- 05(!LLJlTOR (OIL - G- WlI?/JlBLl UIlIf liND (ONIJfN5fR.0002511r. - 1(-LOOP JIJOf - o-nx (OND. 005111: • ©192~ !J.N t.. . ·H!.C. ... :--~YNO' 20 RADIO AGE for June, 1924 The Magazine of the Hour at high broadcasting frequencies still per­ Danger from plate-grid feed back and dyne depends more on the fact that the sist. For the complete elimination of the regeneration ceases at about 1.500 meters transformers are tuned to meet each sep­ grid-plate condenser effect we must take wave length with ordinary commercial arate incoming signal than upon the prin­ up still another method of reducing the tubes having the usual internal capacities. ciple of neutralization itself. This, how­ reaction, and this is to reduce the capaci­ At 2,000 meters there is very little chance ever, requires several variable condensers ' tance by a reduction in the frequency of for free osc illation to develop and there and as many controls as there are stages the input current. is a much less tendency toward picking of amplification which adds to the diffi­ With any condenser the capacity varies up in terference than at the higher wave culty of tuning. with the area of the two metal plates, the lengths. The bes t wave length for the With the heterodyne we gain all of the distance between them, the nature of the radio stages from a practical standpoint advantages of the neutrodyne in having insulation between the plates, and the fre­ is still a matter of much discussion, but it closely tuned transformers, and at the quency of the alternating or oscillating would seem that there is a decided limit same time avoid the many controls since current supplied to the condenser. It is, beyond which it is not practical to go. our transformers are tuned once and for of course, impossible to change the ca­ There are circuits which operate very sat­ all time by means of a fixed condenser set pacity of the tube grid-plate condenser isfactorily at from 1,750 to 3,000 meters f or the constant wave length. In the by varying the area or spacing of these wave length and as a rule these circuits heterodyne we have only two controls, elements since they are sealed within the are not so noisy as those operating on the wave length (tuning) condenser, and tube, and for the same reason it is im- 5,000 to 10,000 meters. An added ad- the oscillator condenser, while in other

W/RI NG D/':\6RAM FOR IMPROVED

at- p .oOOSHI'

/{+ B-

possible to make changes in the nature of vantage attending the use of the shorter radio frequency systems using tuned the matter between the elements. How­ wave lengths lies in the fact that the radio transformers we have as many condenser ever, it is possible to reduce the capacity frequency transformers are simpler. controls as there are radio frequency stages of the grid and plate by reducing the fre­ With wave lengths approximating 2,000 (plus one). quency or wave length of the current in meters we can construct very cheap, sim­ Operating an ordinary radio frequency the plate and grid, and this is exactly what ple transformers of the air core neutro­ set with untuned condensers is much like is done in the super-heterodyne circuit,. dyne type which need only have from 2 SO trying to operate an ordinary receiving set At wave lengths of 3,000 to 10,000 lo 350 turns of wire in the secondary coil. without tuning controls. At all wave meters the capacity of the grid-plate con­ On 10,000 meters we may. require a thou­ lengths, except one, the reception will be denser is very much lower than at the sand or two thousand turns on the sec­ very weak and the selectivity is greatly ordinary broadcasting range of 300 to 600 ondary, thus both increasing the size and reduced. You can hardly imagine a receiv­ meters, and hence there is much less ten­ the cost of construction. Transformers ing set built without a coupler or without dency to feed back or oscillate on the long of the 5,000 to 10,000 meter class are not a tuning condenser, but this is practically wave lengths. Instead of receiving the easily built at home. equivalent to what takes place when un­ high frequency station currents directly in tuned radio frequency transformers are the ampli fying tubes, the frequency is first Heterodyne Transformers used. If you do 'not believe this, just reduced by the oscillator circuit to that A second point in the consideration of connect an ordinary short wave untuned frequency which gives the least tube con­ the superior efficiency of the heterodyne radio transformer in place of your vario­ denser effect. Theoretically this minimum radio frequency circuit is the great ampli­ coupler and see what happens. capacity would be had at wave lengths just ficationpeak possible with the transform­ There is one advantage in the hetero­ above audible frequency, but practically ers when they are operated at a constant dyne circuit which seems to have escaped it is not desirable to use such long waves frequency or wave length. As they work the notice of the transformer manufac­ because of other effects which develop at a single constant wave length they can turer, and that is the possibility of using in the circuit. A wave length of 10,000 be carefully tuned to this point when they high transformer ratios. With the plate­ meters is probably the longest wave in are built, thus obtaining a maximum ratio grid capacity effect reduced to a minimum common use, and this is far above audible without the necessity of repeated retun­ it would !;eem that higher ratios would be frequency. With wave lengths above 5,000 ings every time that the wave of the sta­ possible than are ordinarily used without meters the circuit is likely to suffer from tion is changed. The ordinary type of danger of the tubes breaking down into interference due to long wave length sta­ ~hort wave untuned transformers designed free oscillations. In the majority of cases tions, and it is much more likely to pick to operate on a wide range btween 200 and the present transformer ratios are in the up noises caused by atmospheric disturb­ 600 meters give a very low amplification nature of t\VO to one, with four to one ances or waves emanating from the elec­ except at one or two points in this range. as a maximum. When ratios of flve to trical circuits of industrial plants and elec­ It is very possible that the great superi­ one, and even eleven to one, are used in tric railway systems. ority of the average home-built neutro- (Continued on page 56.) RADIO AGE for June, 1924 The Magazine of the HollY 21

Adding Radio and Audio to Baby Heterodyne By JOHN B. RATHBUN

N RESPONSE to the many inquiries As shown in the diagram, two air core should preferably be a vernier rheostat. for the addition of radio and audio transformers of the neutrodyne type are As before, (L) is a 50 turn honeycomb I . frequency stages to the baby hetero­ shown at (RFT-l) and (RFT-2), the sec­ coil and (C4) is the condenser controll­ dyne, the following circuit has been de­ ondaries (K) of these transformers being ing regeneration and frequency. vised which gives two stages of radio tuned by the 17 plate (0.00035 mf) con­ This brings us to the audio frequency frequency amplification, detector, and two densers marked (C2) and (C3). The tubes (4) and (5) which are controlled by stages of audio frequency amplification. sec ondary coils (K) are wound with 66 the single rheostat (R3). The iron core This five tube set requires the usual pre­ turns of No. 24 D.C.C. wire, while the radio frequency transformers (AT-I) and cautions against setting up free oscilla­ primary coils (J) have only eight turns (AT-2) can be any good make, preferably tions in the tubes and feed-backs that of the same wire, this giving a transformer with a ratio of five to one, although other must be taken with all radio frequency ratio of over eight to one. These can be ratios can also be used. For maximum sets, but when everything is adjusted it made at home, winding the coils on 3-inch amplification (AT-I) can have a ten to will pull in distance with probably twice paper or bakelite tubes, but it is easier one ratio, but for clear undistorted speech the range of the detector alone. The and cheaper to buy standard neutrodyne a five to one ratio is best. You will note audio stages of course permit of loud coils for this purpose. If the coils are that the four terminals of these transform­ speaker operation upon fairly distant sta­ wound at home, care must be taken to ers are marked (P), (G), (*B) and (-F) tions. wind the small coil (J) at one end of the as usually found on the posts of such The basis of this circuit is the single tube so that it is separated by a short deviCes. tube heterodyne which occupies the po­ distance from the coil (K). For maximum amplification, reduced sition in the circuit marked "detector," The use of the above transformers, distortion, and minimum " B" battery cur­ and this will be quickly recognized by while giving the maximum results, gives rent, a small bias ing battery marked "C" those who have read or used the article in us a great many controls to handle, or is used with its negative pole connected to the February issue of Radio Age. The in fact we have four tuning controls which the (-F) posts of both audio transform­ two coilers marked (M-N) correspond to are quite critical. While this gives almost ers as shown. This is simply a small the coils (M-N) in the February issue 100 percent selec tivity, yet it is tedious three cell fla shlight battery giving a po­ and are almost historic by this time. It and decidedly bothersome for the begin­ tential of about 4.5 volts, and is con­ should be particularly noted that the de­ ner. The use of ordinary untuned radio nected directly into the circuit as there tector circuit is supplied with plate cur­ frequency transformers at these points, is no flow of current when the set is idle. rent by a separate "B" battery (-B2, * such as the Erla, Acme, RasIa, and others, The output of the set is at the extreme B2) which is necessary for proper oper­ does away with the necessity of the con­ right, and no jacks are provided since in ation. The first " B" battery supplies de nsers (C2) and (C3), and thus reduces a circuit of this sort it is not advisable both the radio and audio frequency cir­ the controls to two units. The volume to introduce any more capacity than is cuits in the usual manner. and distance will suffer accordingly but absolutely necessary. The first change necessary is the re­ this sacrifice is sometimes advisable in For the radio and audio stages, as well moval of the old fixed coupler from the view of the difficulties just mentioned. as for the detector circuit itself, about simple detector circuit. This is removed The two radio frequency tubes (1) and 67 volts of "B" battery will give the best and used as the first tuning inductance (2) are controlled by a single rheostat results. For economy, we can use 45 volts at (FC) at the extreme left where the (Rl ), and the grid potential is regulated at (B2), but a higher voltage will give primary and secondary coils are marked by the 200 ohm potentiometer (PO) . The better results. It goes without saying (P) and (S) respectively. In the de­ latter is pecessary to prevent oscillations that all of the tubes, detector tube (3) tector circuit, the tuning unit is replaced in these tubes but is not critical. The included, must be hard amplifying tubes, by the ordinary neutrodyne transformer detector tube (3) is contained in the cir­ such as the UV-201A, C-301 A and UV-199 (RFT-2) or by another radio frequency cuit already familiar to our readers and or C-299. A soft tube like the UV-200 transformer as will be described later. is controlled by the rheostat (R2). This will not work at the high plate voltages

SINGLE TUBE HETERODYNE WITH TWO RADIO AND TWO AUDIO 5TAGES (SEE RADIO AGE ,FEBRUARY, 1924)

1------RADIO FREe;>. STAGE'S ----_Tr- --- DETECTOR-----t"---~-A UpIO AMPLI J=;F.,---...-jl OUTPUT Fe

+o---O------~--~~~------~~~----_O~------~------6_------~

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J.B.R. 22 kADIO AGEjor June, 1924 The .L1Iagazille oj the floll r

given. Please, please, please do not use nai" is a se ries of very long da~hes with nals from the Bureau of Standards is as either the WD-11 or WD-12 tubes in a the call lette,s W\VV intervening. fo llows : circuit like this, and then write in and This signal continues fo r about four ask why you are not getting results. If Easter n S tandard minutes. The " announcements" are on Time June 5 June 20 July 7 I had my way about it I would pass a the same frequency as the "standard fre­ 11:00 to 11-08 P. M ...... lOO SSO 1363 (1000) (545) (220, law against the use of WD-11 's in every­ quency signal" just transmitted, and con­ II :12 to 11.20 P. !II .. ..•. .11 '; 6~n 14.10 (952) 14611 (210, thing except Ultra-Audions and similar tain a statement of the measured fre­ II :24 10 11 :32 P. M ...... 145 750 I~ r.o (8691 (400, (200, single circuit sets. quency. An announcement of the next II ;.16 to 11 :44 1'. M " .... 375 SJ3 1600 frequency to be transmitted is then given. (8001 (.160) (l S71 X ow returning to the front end of the 11 :48 to 11 :56 I'. 111., .... 42~ 940 1'00 There is then a four-minute inter\'al while (705 ) (.1161 (] 761 cingus at the left, we see our old f rier.d 12 .00 10 12:0~ A , 111. . ., .. sao 1050 1800 the transmitting set is adjusted for the 11>1)0) (21;51 (1671 the fixed coupler (FC), alias the ·',,'izard" 12:12 10 12:20 A 1\1...... wo 1150 IQOO coil, alias several other names. This con­ next frequency. lSO;1) (2611 (] ;;8) The schedule of standard h:quency sig- 12 .24 to 12 :.12 A , M ..... (i47 11 so 20.JO tail's n turns in the primary (p) and 60 (~~50) (240) (ISO) turns in the secondary (S), all wound on a three inch tube with No. 24 D.C.C. or ~ o. 26 D.C.C. wire. Full details were given for the construction of this coil. Yes. vou can also use a four inch tube or a fiYe- inch tube, providing that you reduce the number of turns in proportion. The tuner coil (FC) has its secondary coil tuned by the same old 23 plate (0.0005) condenser that we used in the old detector circuit, and is indicated by (C1). This will require a 7x26-inch or a 7x28-inch panel, the latter preferred if neutrodyne type coils are used for radio frequency transformers. With these trans­ fonners, d-o not have the coils closer than 5.5-inch centers, and turn them at an angle of 45 degrees so that the bores of the tubes will not be in line. If each trans­ former (RFT -1, RFT-2) is turned at an angle of -1-5 degrees with the horizontal and vertical, then there will be no " feed­ back" nor regeneration between the radio frequency stages, but if all the trans­ formers are in line, then you will get no results whatever for the energy will be short circuited between the transformers and the radio tubes will not amplify. Latest Radio Frequency Transmissions The Bureau of Standards is transmit­ ting special signals of standard frequency about twice a month. The next schedule is announced below. The signals can be heard and utilized in general east of the I\Iississippi River. These special signals of standard fre­ quency are of use to testing laboratories, transmitting s tat ion s, operators, and olhers in standardizing wave meters and adjusting transmitting and receiving ap­ paratus. The transmissions on June 5 will be of special interest to ship operators, tho~e on July 7 to amateurs, and those on June 20 to broadcasting station oper­ ators. The accuracy of these signals is better than three-tenths of one per cent. Information on how to use them was given in the February, 1923, issue of the Radio Service Bulletin. More detailed in­ formation is given in Bureau of Standards Letter Circular 1'\0. 92, which may be ob­ tained, on application from the Bureau of Standards, \Vashington, D. C. ,\1\ transmissions are by unmodulated continuous-wa\'e telegraphy. A complete frequency transmission inclUdes a " gen­ eral call," a "standard frequency signal." Kadel & Herbert Photo. and "announcements." The "general call " AND THE AIR WAS FILLED WITH ELOQUENCE is gi\'en at the beginning of the eight-m in­ Leave that to William Jennings Bryan. F or the first time the famous publicist delivered an addres s recently on "The E lection of 1924." Here he i.s shown before ute period and continues for about two the microphone of WJZ at the Hotel Commodore, N ew York City. By !l1eal!-s minutes. This includes a statement of the of radio millions were able to hear M r. B ryan's fiery address for the first tIme in frequency, The "standard frequency sig- their lives. RADIO AGE for June, 1924 The Magazine of the Hour 23

ate

Schenectady Announcers Radio, the newest industry and science, now claims the labor of 250,000 people and the leisure and rest of countless more. In the broadcasting branch of the science a new vocation has developed, that of the radio announcer. To be a successful announcer something more than a pleasing voice and clear enun­ ciation are required. The ideal announcer i!' a musician with a knowledge of com­ posers and their work; he shQuld be a linguist familiar with French, Italian and Gennan; he should be able in an emer­ gency to make an announcement in Eng­ lishwithout confusion and free from gram­ matical errors. He must be tactful in re­ ceiving artists and instructing them in proper position before the microphone, Singers and speakers accustomed to public appearance very often develop microphone fright, not because the studio surroundings are overpowering but be­ cause they miss the stimulating presence of an audience; it is difficult to visualize the vast radio audience, headphones on head or grouped about loud speakers. The announcer's duties are not limited to his appearance before the microphone At WGY, the popular station of the Gen­ eral Electric Company at Schenectady, rehearsals are conducted by one of the group of six announcers at WGY By means of the try-out poor singers are saved the embarrassment of failure before the' microphone. The rehearsal also serves to demonstrate that certain voices have not the quality for radio transmis sion. Sometimes the finished and success­ ful singer is found to have a voice Kadel & Herbert Photo unsuited for radio transmission and on the THE THREE MUSKETEERS OF WLS other hand a singer whose voice is too These jolly chaps keep their ethereal customers smiling from WLS, the Sears­ weak for public hall or theatre, sometimes Roebuck Agricultural Foundation Station at Chicago. From left to right they are possesses quality and tone which win in­ George D. Hay, the "solemn owl of Memphis," and chief announcer of WLS; stantaneous popularity with the radio Ford Rush, director of music and Robert Northrup, assistant announcer and enter­ audience. tainer. Mr. Hay is shown with the locomotive whistle that made him famous Four of the six announcers at WGY among the fans down in Dixie. are vocal soloists and may, in the event of an emergency, such as the failure of announcer, is director of a boy choir in an scheduled artists to arrive, step before the Amsterdam, N. Y., church. William Fay, WANTED: Contributions to the micmphone and give a creditable per­ the last to join the announcer force at Pick-ups Page. Lists of stations formance. Kolin Hager, the chief an­ WGY, is a baritone, and his voice has heard; see February 1924 issue of nouncer, has been associated with WGY brought him many fan letters. RADIO AGE for particulars. Short since the station opened, He is a trained The other announcers at Schenectady stories under 250 words in length; musician, linguist and public speaker. station are Robert Weidaw, who gives jokes and anecdotes; brief sketches When a boy he was soprano soloist in an much of his time to the executive work of of humorous incidents in radio build­ Albany Cathedral and is now baritone the studio, and Edward H. Smith, who is ing; summaries of experiments with soloist in a Schenectady church. Carl director and leading man of the players, receiving sets; listening experiences; Jester is a tenor with a thorough musical and assists in planning feature programs photographs, wiring diagrams; also education, and for the past year he has such as Uncle Josh's golden wedding, and any other interesting items. Ad­ di::ected the WGY Light Opera Company minstrel shows. An entire evening's pro­ dress: RADIO AGE, Box PP, 500 in its various appearances. gram may be put on by the announcers N. Dearborn St., Chicago, Ill. Asa O. Coggeshall, also a tenor, a third without the aid of outside talent. 24 RADIO AGE for June, 1924 The Magazine of the Hour

Kadel & HCl'lIert Photo. A NEW ERA IN NEWSPAPER PUBLISHING A group of astonished newspaper editors, electrical and radio engineers at the American Newspaper Publishers' Conven­ tion in New York watched a radio typewriter being operated by a person who was sitting in an experimental la,boratory more than two miles away. The "copy" was received and typed at a rate 'of sixty-five words a minute and with an accuracy of 99% per cent. The machine operates on a short wave tuner ranging from 60 to 150 meters, with detector and amplifier. The new device is expected to revolutionize transmission of newspaper messages.

First to Hear McMillan Gets $100 Phonograph Broadcast Succeeds WTAM: "Takes the Cake" The first amateur who succeeds in pick­ Successful broadcasting and re-record­ George A. Rudd, a Cleveland confec­ ing up the Donald B. McMillan station, ing of phonograph records have been ac­ tionery manufacturer, enjoyed the special WJ:\P, on the Schooner Bowdoin, now complished by experimenters at WGN, Easter concert from WTAM so well that frozen in 'within eleven degrees of the the Chicago Tdbune-Zenith station at he bought a gaily decorated cake and sent North Pole, will be awarded $100.00 in Chicago. it to the radio artists as an appreciation. gold by U. ]. Herrman. managing director The cake measured eighteen inches in When \\'GN went on the air \'lith its of the Radio Manufacturers' Show As ­ diameter and was six inches high. The inaugural program Saturday, March 29, sociation, which will hold radio shows in decorations were in all co lors of the rain­ Kew York and Chicago this Autumn. Frank Hoyt. inventor of a new method of bow. The pastry donation was heartily rt'c ording broadcast reception, tuned in at To the next amateur who reports a con­ received by the radio artists, and Art his laboratories in New York City and firmed reception of the McMillan expedi­ Herske, the announcer, became so en­ recorded his reception of the program on tion's t ransmission, E. F. McDonald Jr., thused over it that he forgot to sign off. president of the Zenith Radio Corpora­ aluminum disks. tion, will award a Zenith receiving set­ He succeeded in reco;-ding virtually all an . exact duplicate of the one in use on the Bowdoin. of the program, which continued from 6 Girl Wins Radio Drama Prize p. m. Saturday to 6 a. m. Sunday. Some The offe rs are made to stimulate watch­ of the records were brought to Chicago "A Million Casks of Pronto," a6(omedy ful ness on the part of amateurs who can and under 1\1r. Hoyt's supervision they drama of business li fe , WOn first prize in leceive code messages from \YJ:\P. Noth­ were broadcast as a part of WGN's regular the radio drama competition conducted ing has been heard from the McMillan by WGY, the Genend Electric ~tatio, at party since l\Iay 10. Amateurs who pick program for Donald B. McMillan, whose ship is frozen in cleven degrees from the Schenectady. Miss Agnes l\liller, of 150 up messages sent from WN P are asked to East Seventy-second Street, New York, telegraph to Mr. H errman, at 12 7 North ~o r th Pole. wrote the play, whi ch will bring her a cash Dearborn Street, Chicago. or to ~Ir l\Ic­ This broadcast of a previous recording Donald at 332 South l\Iichigan Avenue, prize of $500.00. The object of the com­ was received in Chicago and New York, petition was to develop a type of play Chicago, care the Zenith Radio Corpora­ and the broadcasts were received with especially adapted to radio presell~:\tion, tion. sufficient clarity and volume to be re­ and which tells its story through ait :J.p.oeal T o the sender of the first telegram con­ corded again. This is said to be the first taining a message fro m the l\Ici\lillan tim e such an experiment has succes;;flllly to the ear and imagination instead of to party, which it is poss ible to confum, bee n carried out on a large scale. accord­ the eye. The winning play will be pre­ SlOO.OO in gold will be awarded. ing to Ben Garetson, director of WGN. sented by the WGY Players soon. RADIO AGE for June, 1924 The Magazine of the Hour 25

HE NEXT member of Congress who tries to put an N AGITATOR has appeared in the East who con­ obstacle in the way of radio's progress will know he A tends that the government should force broadcasting .T has a fight ahead of him. The recent victory of stations to give both sides of every political question an radio's friends in the United States Senate and the defeat equal opportunity to use their microphones for the pur­ of the proposal to inflict a tax of 10 per cent On all radio products proves that. pose of haranguing the public. \ Vith equal justice the government could force the newspapers to publish two For some reason a Senate commlttee had fi gured it editorial pages-one Republican and the other Demo­ would be a smart bit of legislation to place a burden on cratic. the infant industry. There were senators who insisted

they saw nothing illogical in forcing a fee from the [J schoolboy who undertook to build a receiving set-after [J' ''' , . [J EJ ii' ',ill! ,,,II' [J being taught how to build it in a public school. Let the EJ taxpayers finance the technical education of a radio-Iovin e­ boy in a public school and then let the government in;~ ECRET ARY HOOVER, of the Department of Com­ pose a tax on what the boy makes. S merce, is to call another national con ference for the discussion of radio problems. H e says the most serious That is not an exaggerated statement of the attitude of menace to the proper enjoyment of radio broadcasting at the pro-tax senators. Abandon this tax plan and give radio a full and free chance to show that it is a necessity, this time is interference. Wave lengths of stations in the rather than a luxury? No, S-I-R! The senators wanted same community are within too narrow a band. More $10,000,000 and they were going to raise it in radio le\'ies. power to the Hoover elbow!

But they did not. Radio interests combined to make [J the voice of radio heard down in \Vashington. It was a al ii! """,,, , , !I[J [JiI 'l! ',"ii"" ','S giant voice when it spoke. Manufacturers of radio sets S and equipment used the newspapers. the direct mail cam­ paigns and the broadcasting stations to in form the radio HEN the S.S. " Columbus," a new ocean grey­ public of what was going forward. T he users and pro­ W hound, arrived in New York recently, there was spective users of radio equipment were assured that they considerable interest in two lifeboats ca rried by the liner. would ultimately pay the tax. These had been equipped with both transmitting and re­ The country was astonished when the word was passed ceiving apparatus. Once launched they readily could be on to the big cities and the cross-road hamlets. T ax transformed into sending or receiving stations. T he vast radio? Put a brake on an art in which the United States possibilities of this development of radio are apparent at had just fairly shown that this country led the world in a glance. E ngineers have devised methods of using radio development of that art? Burden a science that was just to locate without loss of time miners who may be im­ beginning to show its tremendous value in the dissemina­ prisoned by explosions or other accidents under ground. tion of information and entertainment ? Interfere with O ne railroad has its own broadcasting station with a sys­ the development of a science that had become an indis­ tem of minor transmitting and receiving stations. Chi­ pensable aid to the mariner and to commerce and world communication? Put a brake on a device that was knit­ cago has a broadcasting station specially devoted to the ting the peoples of all sections into a closer relationship interests of the farmer. Radi o gives shi ps their bearings and bringing the university course and the musical college on .storm-swept coasts. Radio has taken the place of the to humble homes of millions? Put a tax on time signals, time regulator in the watchmaker's shop window ; Amer­ weather reports, United States agricultural reports, news ica is setting its clock by the signal from the broadcasting bulletins, market quotations? T ax a science that is and station. Radio is fi nding lost persons and lost property. will be a vital part of the army and navy in peace and Radio is helping to run dowil fugitive criminals. Radio war? is the li vest thing in the United States. It is the only Well, the plq.n was fortunate in enjoying a painless buoyantly ali ve industry in the country at this time. And death. The radio public was asked to tell Congress what yet the things that radio has accomplished and is accom­ it thought. The result was a protest that left nothing to plishing are onl y a begin ning. T he new season is to see be desired in the way of volume. Letters and telegram s radio step fo rth as a real giant, SlIre of its strength at last. swept in upon Washington. Politicians suddenly founeI themselves blinking into a calcium light. T hey di scovered r:::J D i i , i '"'''' i [J [J i " ""'" i [J that this is a radio republic. The tax amendment came [J !I ,,, "'" up in a session of the Senate and was voted down and out. It was beaten at a moment when the fans thought they were making only the preliminary moves to defeat it. GOVERN MENT radio expert predicts that A before 1924 is over t he et her w ill bc cntirely We would suggest that the next senator who wants to free of all interference. I f we ever reach such a stage ease the burden on some private interest by tightening up on radio should go about it onl y after taking an aeroplane of radi o bliss, tuning in 0 11 your favorite station w ill voyage over our little old country and c0U19ting the radio be just like turning on a phonograph. P lease, Mr. aerials on American roofs. Expert, lca\'e us a little interference just for fun. 26 RADIO AGE for June, 1924 The Magazine of the Holtr Radio Does Not Electrocute

ASHINGTON, D. C.-Radio, un­ Antennas Necessary ulations and precautions for the erectilon fortunately and un jus t I y, fre­ Some sort of an aerial is necessary to and use of aerials, and will report suon. W quently gets a "black eye" through every receiving set, and it is well known Concerning antennas in general, Doctor improper headlines and sometimes badly that an outside aerial is better than an Dellenge r pointed out that there is nothing written stories in the daily press. The inside one or a loop, except in specially about them to justify the large amount of headline, "Electrocuted by Radio," which constructed high power tube receivers. worry and uncertainty they seem to give According to Dr. J. H. Dellenger, chief many uninitiated fans. An antenna he · recently appeared in a local paper, was explained, is the "harness" that con ~e rt s not only misleading, but wrong according of the Radio Laboratory of the Bureau of Standards, a fairly long and high an­ the radio wave motions into currents to the brief story itself. In the first place, tenna is the cheapest way to get loud which operate the receivjng set. Almost radio itself cannot electrocute anyone, ex­ signals with the simplest receiving sets. any sort will work for a broadcast receiv­ cept in cas e of transmitting stations "To get the best results, an outdoor an­ ing set, he said, adding that fans do not where high-power supply is used. At the tenna, used for great distances or for need to imitate the amateur transmitters radio receiving end, radio is not dan­ crystal sets, one should use a single, con­ and erect elaborate antennas of several gerous. tinuous copper wire, SO to 150 feet long, wires. direct from the set to the highest point It is even doubtful if the high-frequency Single Wire Best power put into transmitting antenna at b.ig available at the far end, supported by good insulators, such as porcelain or glass, A general antenna for reception should commercial stations could kill, although it and kept well away from trees and build­ he a single wire running from the set, is admittedly dangerous to touch bare ings. "Keep the antenna away from pos­ direct if possible to a convelliently high wire, the motor-generator, bus-bars, or sible accidental con t act with electric point at the far end. It does not have to the transmitting circuits, as a shock or wires," he admonishes. he horizontal, a slight angle is sometimes burn might result. Only at high-powered, advantageous, and it does not matter in low frequency stations could serious re­ Are Antennas Dangerous? what direction the antenna points. Little sults occur. Receiving sets are not dan­ Replying to the query: "Are antennas directional difference is noted in reception, gerous, according to all well-informed dangerous?". Doctor Dellenger said: except in special and long antennas. "The lightning hazard is practically nil. "Antenna length," he sums up, "is a experts, unless of course they are charged Only for outside antennas need lightning compromise between loudness of signals by outside electric power. protection be considered at all, it is very and freedom from interference." Referring again to the headline and the simple. A small and cheap device called The public trend is no longer for dis­ story of the unfortunate lad, who, it de­ a lightning arrester should be connected tance, but quality of reception, he be­ veloped, let his antenna come into con­ between the antenna and the ground wire lieves. If, however, one wants to astonish tact with an electric wire charged with on receiving sets. An antenna is no more his friends with a long distance record.. he 2,3 00 volts, it is readily seen that he was likely to bring lightning into a house or explains, let him erect a "whale of a long not electrocuted by radio but by an elec­ apartment than are overhead telephones antenna," or, use a very sensitive, many­ tric power line. It would have been the or electric light wires. The principal haz­ tube receiving set, or both, and pile up a same had he been stringing a wire clothes­ ard from antennas is from stringing out­ record. Receiving sets using electron line, although his death would not have door antennas over or near electric light tubes work well with indoor antennas or been charged to a clothes-line. An autoist wires. A number of persons have met loops, the latter aiding in directional who stalls his machine on a railway track death. by electrocution from this cause." effects, but these antennas are relatively and is killed by an express train is not said A special committee on the National Elec­ weak and therefore the signals must be to have been killed by an automobile. trical Safety Code is now drawing up reg- amplified, he explained.

A Sure-Fire Reflex (Continued from page 15.) ff~CRY~T4L~~TEC1VI? then be replaced by smaller sized instru­ AUDIO ,..... ments. The neutroformer would be dis­ 7',QANS R,40/0~ sembled and the condenser mounted in nc>AI\fS. the same place. The transformer coils, however, would be mounted in the space di rectly back of the crystal detector to conserve space. This would make room for the A and B batteries in the bottom of the cabinet. The A battery in such _____-1. 5' case would, of course, be made up of flash­ 0002 light batteries. Such a set may be taken to the summer camp and will provide plenty of enter­ tainment on the hike or at the fireside. A portable wire wound on a good sized spool with a couple insulators will be ahout all that is necessary for an antenna. ZOO -4(1() w The writer would be pleased to hear per­ sonally from anyone who builds this set and offers to answer any questions relative to troubles encountered in getting it into operation. Figure 7. The wiring diagram of the Sure Fire Refl ex Receiver. RADIO AGE for June, 1924 The Magazine of lh Hour 27

HE business of choosing the letter" to be used for publication in the CONTRIBUTORS T Pickups Pages is getting to be quite a problem. It is a wonderful sight to see C. A. Wiriams J. J. Drey C. R. Williams all the letters sent in by fellow fans offer­ ing suggestions and contributing hints, DIAL TWISTERS lists, stories and other matter, nearly all of which say in the last line of their let­ Name Address Circuit S. J. Craig ...... 1390 12 th Ave., New W estminster, B. c., Can ...... Honeycomb ters, I hope I may be able to see in print H. K. Hathaway ...... A41 Brunswick St., Halifax, N. 5., Can ...... Honeycomb in your next issue. John Sabiston ...... Bay Sbore, L. I., New york ...... Atwater K en t George A. Holly ...... 10214 Adams Ave., Cleveland, 0 ...... Erla Triplex As much as we'd like to, we can't print Mr. "A. CHart ...... 2336 Lawrence Ave., Chicago, III ...... First Tube T. W. RobinsoOl ...... Britton, Okla ...... Three Circuit all of them. Sometimes it is hard to have C. W. Nestler ...... Flaxton, N. Oak ...... Single Circuit to turn down a nicely arranged list, or a J. P. Cooper ...... c/ 'J Southland Cotton Co., ME.mphis , Tenn ...... Cockaday Ray EIJis ...... Durant, Ia. (Cedar County) ...... Rdnartz little suggestion that, while it may be John Escher ...... Spring Lane, Englewood, N. J ...... Single Circuit trivial in nature, carries with it a good A. P. Smith ...... RFD No.8, Bangor, Me ...... Ultra Audion Richard H. Starkie ...... 950 St. Marks Ave., Brooklyn, N. Y ...... R eflex 1 Tube idea. C. B. Gcmnon ...... 1731 Ensor St., Baltimore, Md ...... Reinartz Rege nerator Kenneth B. Glass ...... 144 S. Mt. Vernon Ave., Uniontown, Pa ...... Reinartz Regenerator So if you meet a fellow wearing a little E.· Brand Boylan ...... 1106 West 8th St., Wilmington, Del...... Single Circuit button about 0/16 of an inch wide, with the Clarence Easton ...... 35 S. Raymond, Rm.320, Bradley Bldg., P asadena, Calif. . Rosenblo()m B. Drum ...... 99 S. Main St., Asbury Pk, N. J ...... Three Circiut following appearance: E. L. Blass ...... 716 Oakluna Blvd., Fort Smith, A r k ...... Neutrodyne M. S. Miller ...... 1506 Jones St., Souix City, l a ...... Single Circuit Eden W. Hollon ...... 3096 Coplin Ave., Detroit, Mich ...... Neutrodyne Francls E. Chrestien ...... 416 W. Embargo St., Rome, N. Y ...... Single Circuit W. Eichler ...... 4438 N. Artesian Ave., Chicago-, m ...... Single Circuit August Strom ...... Miller, Ind ...... Single Circuit E. L. Ludell ...... Shelbyville, III ...... Long 45 Edward S agle ...... 2509 N. Bouvier St., Philadelphia, P .o ...... Three Circuit Joseph Ross ...... 1056 Greene Ave., Brooklyn, N. Y ...... Honeycomb Robert E. Boyle ...... 133 West Div. St., Fond du Lac, W is ...... Westinghouse DA A. M. Boyenga ...... Greene, la ...... Single. Circuit

This is the emblem which says that a fellow has contributed something to the While they're laughing up their attribute the remarkable results that common good of the Dial Twisters. Do sleeves, I laugh up my vest-and last this fateful Reinartz accomplishes. you want one? Does your record entitle laughs best because they all respect Since your publication I am flooded you to one? my ideas as to radio construction, and with inquiries as to my hookup. My I am very sure that one of them is business duties throughout the day secretly developing some idea of his occupy the greater portion of my you will know that he has contributed a in an effort to be recognized as I am. time, leaving me very little time for list of stations that was meritorious; that private correspondence. I greatly ap­ he submitted a good suggestion that we Incidentally, the department editor preciate the enthusiasm displayed by h D. ve on file to refer to some fan that wants to say that the response to the re­ so many of my brother fans. For needs it, or that he has done other good quest for information on the part of read­ their convenience I am submitting a work for his brother Dial Twisters. ers who have Super-Heterodyne receivers diagram of my hookup, as I have As a matter of form, the f~llow s who (the request was published in the March found it through various experiments get their names and contributions in print issue) has been very small indeed. We and finally di scovered that the hook­ will be given a button as well, they hav­ got an offer from one fellow who has a up in this form is terrifically loud and ing contributed something of value. super lonstructed after the November clear in volume and exceptionally sen­ We sent out a few dozen of these little issue, which was never fulfilled. Where sitive to distance. I have received buttons as an experiment to various have the rest of you been since 1898? stations everywhere in the U. S. and "fans" who sent in lists and got some of Let's have some response! many portions of Canada, all on loud the following replies: Before you start reading the rest of the speaker. I do not use ear phones department matter, don't forget to look at all. Received your emblem this morn­ over that Static Puncturing Contest. We In this diagram you will note the ing and I felt prouder than the town hope to get some nice lists. specifications for the winding of the constable when the office force asked THE PICKUPS EDITOR. coil, which I have found in this form me what I got it for. covers broadcasting stations with Everybody wants to know how to "Let our hookups be your guide" is the wave lengths from 150 to 600 meters. get one. motto of Mr. J. J. Drey, who contributes I have also discovered that the single . . the suggestion which I sent the following letter, which we think is very cotton-covered wire gives louder and you some time ago with reference to interesting and highly instructive: clearer signals. The coil can be the mounting of homemade spider­ wound on any ordinary spider frame web coils, which was acknowledged RADIO AGE, that can be purchased at any radio with your little button, certainly Gentlemen: shop. It is also important that the makes me very happy. I showed the In the April issue of your valuable plate coil and the grid coil should idea to several of my radio friends, magazine you published the excep­ both be wound in the same direction, who scoffed and laughed until you tional good results I am experi­ clockwise. It is necessary for clear, told me that the idea was a good one encing with the Reinartz hookup, in sharp tuning that the filament lead on and gave me the button to show your which through experiments I discov­ the secondary radio frequency trans­ appreciation. ered a few valuable leads, to which I former should lead to the s lidjn~ or 28 RADIO AGE for June, 1924 The Magazine of the Hour

;4UO/O-v PMGL 5:.1 / TRANS.~ 5::1 P ~ P G

/6fZ

"----N-:-:-iI! IIIII [l lllllll--::::p :----1-----..J bO-~OV Fif!.ure 3. A diagram of the receiver described by Mr. J. J. Drey. Note especially the winding of the coils.

third arm of the potentiometer. I tions change daily. Varying the grid This set has been constructed as have also discovered that by putting clears the distant stations up remark­ indicated and vIi'orks wonderfully in a micafix condenser from the plate ably. I have found it very important my home. of the detector tube to the negative and I fully realize that ev~ry radio Very trury yours, B battery lead will prevent radiation fan wants to reach distance. As I M. C. WILLIAMS. and the stations just simply walk in. have stated before, I have heard prac­ Box 353, Rantoul, Ill. Tuning must be done slowly. tically every leading broadcasting sta­ In using the 6-volt storage battery, tion in the U. S., and this I know COIL DATA: Secondary or stator wherein the UV200 tube for the de­ every fan desires. should be 4 inches in diameter, simi­ tector and UV201A's for amplifiers I am at present experimenting with lar in design to coils sold in Kre~ge's are used, the C battery is not neces­ numerous new hookups, as experi­ stores. Wound with 25 turns of No. sary because of the placing of the menting seems to be my favorite pas­ 22 D. S. C. wire. commencing about micafix condenser across the primary time. But the fateful Reinartz is not o inch (one-half inch) from Totor of the first audio frequency trans­ touched. It brings in the stations shaft and top edge of tube. former. The condenser from the clear and loud every night. ROTOR OR TICKLER: Similar in de­ plate of the detector tube connected In conclusion I can say that any of sign to those sold in Kresge's stores. to the negative B batterv makes the my radio fan brothers who want a Wound with 18 turns of No. 22 D. S. grid circuit very quiet and clear. But clear, loud, far-reaching set should C. wire, commencing at outer edges where the dry cell tubes are used, it is follow these instructions and he will and winding towards center, leaving advisable to insert a C battery of write RADIO AGE a long letter of a space in center. approximately 10 to 4 % volts. This thanks, because I have discovered PL-HE REACTANCE COIT.: Similar depends according to the wiring. It that the hookups in RADIO AGE are in design and size as the above rotor. is also important that a vernier or car­ something to be proud of. Wound with 30 turns of D. S. C. bon rheostat be used with the detector I remain, wire, commencing about ~ inch from tube. because this circuit tunes excep­ Yours sincerely. top and rotor shaft hole. tionally sharp and is very selective. I ]. ]. DREY. GRID· AND PLATE CO NDENSERS: also recommended the shielding of the Iron River. Mich. .00055. panel · with a sheet of aluminum or Loop: Very good results should he thin copper sheet. covering the por­ The Reinartz bugs will no doubt oscil­ obtained by connecting the loop to tions of the two condensers. Also. late and radiate nothing but pure delight the aerial and ground binding posts the plate should be attached to the and gratitude for this generous letter of through a small fixed condenser. ground connection, to prevent body Mr. Drey's, and the department editor Better results, however, may be ob­ capacity. In fact, my machine is so wants to say that we hope Mr. Drey will tained by grounding the negative side well balanced that body capacity is let us have the benefit of his later ideas of the filament and connecting a small not known. \Vhen the condensers are and experiments. aerial strung across the room to the attached to the panel it is important stationary plates of the first variable that a thin sheet of medium weight We present herewith some data which condenser. oiled paper be inserted between the should be. of interest to those experiment­ TUBE ARRANGEMENT: Tubes may shielding plate and the end of the con­ ing with the Superdyne receiver. Mr. M. be arranged in any manner to suit denser so that stator screws of the C. Williams is connected with the Air the fancy of the builder, but remem­ condenser will not come in metallic Service Technical School at Rantoul, Ill., ber that the leads which carry radio contact to the shielding plate. and has submitted some most interesting frequency current must be very short I have found through various ex­ and enlightening data on the construction and direct. periments that the proper ratio audio and choice of apparatus for this receiver. WIRING: The wiring of t he fila­ transformers to be used in the first ment and other parts at more or less stage should be either a 5 to 1 or RADIO AGE, ground potential should run near the 6 to 1; not higher. The second audio Gentlemen: front of the panel and the rotary transformer should be a 3 or 3 ~ to l. Attached herewith find print and plates of the variable condensers The grid leak should be variable from "writeup" on the Superdyne, which should be as near to ground potential 1 to 5 megs. This I have found to I am submitting to your magazine, in as possible to reduce stray capacity assist greatly in receiving stations on which I am intensely interested, and from the hands of the operator. All long distances. when climatic condi- of which I never fail to get a copy. wires from the grid and plate circuits RADIO AGEJor June, 1924 The Magazine oj the Hour 29 should be far back from the panel and separated f rom themselves and everything else as far as possible. RADIO FREQUENCY STAGE: A great deal depends on the construction of this stage whether it really beats a regenerative detector and two-stage audio, or not. The main thing to re­ member is to hold the rad-io fre­ quency tube from oscillating when both tuned circuits are brought to absolute resonance. With the tickler winding on the rotor described above both halves are connected in series so that the windings are in the same direction on the halves. It does not really matter which direction the rotor or stator is wound as they can be shifted by turning rotor over. By reversing the coil in the plate cir­ cuit will change audibility of signals sometimes. OPERATION: The operation is apt to be a bit puzzling at first. With the aerial connected, also ground, etc., set the resonator dial (condenser) to the left and the wave length dial to the right, say at about 20, and ad­ vance the stabilizer from the "zero " or full reversed position until a click is heard in the phones or loud speak­ er; this denotes oscillation. Work slowly on the edge of this point, com­ ing forward with the resonator and wave length dials until the old fa­ miliar squeal of a station is heard. Tune this in at the loudest and then reduce the stabilizer little by little and follow up with the resonator keeping the squeal at a low tone until finally the squeal is entirely lost and speech comes in clear. Then try the wave length dial for micrometer ad­ justment to reh:.e the music or speech. Experience alone is the best teacher with this sensitive receiver. PARTS USED: 1 special coupler, stator and rotor; 1 plate inductance ; 5 rheostats; 5 freshman condensers; inch; 1 panel, 7-inch by 26-inch ; 2 6 sockets ; 1 cabinet, 7-inch by 26- variable condensers, .00055; 2 trans­ formers, first and second stage; 3 3-inch white dials; 7 binding posts ; 1 input push and pull modern tran5- former; 1 output push and pull mod­ ern transformer; necessary bus-bar and spaghetti. Total cost, about $60.00. RANGE : Unlimited. Easy 10 tune western stations as Los Angeles, etc. (Chicago with loud speaker without resorting to the usual head phones first); volume from KFI resembles a phonograph. Most sensitive set known for the number of tubes used, outside, of the super-heterodyne. GRID LEAK: Some tube!l have a tendency to block or choke when resonance is passcd. This condition may be removed by touching the moistened finger tip to the grid ter­ minal on the socket of the detector tube. However, if this becomes an­ noying it may be further remedied by using a better grid condenser or using a grid leak. One very impor­ tant thing to remember is never conned a grid leak across the grid 30 RADIO AGE f or June, 1924 The Magazine of the Hour

insulating condenser. If a grid leak 84TSWJlT:1I is needed it should be connected from the grid terminal of the detector socket to the positive terminal of the same socket. From two to three megohms are used with hard tubes while it is not necessary with soft tubes. The grid condenser should be a bout .0002 5 and well insula ted.

L EGEND OF FIGURE 1 AA-Antenna wave length condenser for balancing. After once adjusted fo r the particular type of antenna need not be touched again. Many use the small fixed condensers after the one best suited has been tried out. B- Special coupler, stator has 25 turns No. 22 D. S. C. wire, 0 inch from top edge and rotor shaft. Tube 4 inches in diameter. A-Variable condenser .00055 for wave length of station to be tuned in. C-Rotor, feed-back stabilizer, 18 turns on each side No. 22 D. S. C. Figure lb. The layout of the SuperdY1le receiver. wire, connected on inside in series, leaving space on outside between windings. 5-Bradleystat for amplifier tube. best aerial is a single wire about F-Plate inductance, 4-inch tube, 6-Bradleystat for detector tube. seventy feet in length. wound with 30 turns No. 22 D. S. 7- First audio transformer. Do not touch the wave length con­ C. wire, Yz inch from top edge and 8- Rheostat, first audio tube. denser after it has once been tuned rotor holes, if an old variocoupler 9- Rheostat, second audio tube. or balanced with the aerial, for this stator is used. 10- Second audio transformer. will throw the entire set out of tune. E-Rheostats. II- Rheostat for two push and pull Stations one thousand miles can be D-Rheostats. tubes. heard at any time through any inter­ G-Variable grid leak. 12-Radio amplifier tube. ference and loud enough to be heard H-Fixed condenser, .00025. 13-Detector tube. on a Brandes Table Talker one city I- Fixed condensers, .002. 14-First audio tube. block. J-Sheltran transformers, same ratio, IS-Second audio tube. Very much care, indeed, must be 9 to 1. 16 and 17-Push and pull tubes. taken in the wiring and in the selec­ K-Modern push and pull transform­ 18 and 19-Push and pull trans- tion of instruments. It is always bet­ ers. formers. ter to select the very best instru­ 20-"C" battery binding posts. ments and save the later purchase, LEGEN D OF FIGURE 2 21-"A" battery binding posts. for eventually better grades must be Resonator-Condenser .00055. 22-"B" battery binding posts. installed. Stabilizer-Special coupler with sta­ 23- Jack for first audio stage. bilizing rotor. 24-Loud speaker jack. If we were to judge from the corre­ Wave Length-Condenser .00055. spondence of the technical department Rheostats - For amplifier and de­ NOTES with reference to the Super dyne circuit, tector tubes. 3 and 4 rheostats for With the old-fashioned VT1 tubes we would like to say that Mr. Williams' two audio tubes. 5 for the two as detector and all stages of ampli­ data is most welcome. Many fans have P. and P. tubes. fication this is the most sensitive set been asking for more detail with regard obtainable which will work under the to amplification and panel layout, together L EGEND OF FIGURE 3 existing circumstances. with a complete list of parts-and here it I-R esonator condenser. Twenty feet of wire strung around is. Mr. Williams enclosed a well designed 2-Special coupler and stabilizer. the room under molding or around blueprint of the circuit (Figure 3), with 3-Wave length condenser. picture, or straight run through attic, instructions as to the layout of the re­ 4-Plate resonance coil. makes a very good aerial. But the ceiver, and we are sure that he will be amply rewarded for his troubles in the grateful thanks of many DT'S. RADIO AGE, Gentlemen: Since publication of my letter in the April issue I have received a num­ ber of letters from fans asking for th~ circuit diagram, etc. I am therefore sending it to you herewith. Sincerely, CLAREKCE R . WILLIAMS. 7 East St. S., Janesville, Wis.

Mr. Williams' contribution incorporates some very good ideas on a simple, efficient receiver, and the Technical Editor thinks AfA very highly of his letter. We hope the fans will appreciate his efforts in their Figure l c. Arrangeme1lt of the coupler Q1ld plate coils. behalf. RADIO AGE for June, 1924 The Magazine of the Hour 31 RADIO AGE; PWX, WHAM, W]Z, WLAG, me, as I have received about one hun­ Gentlemen: WMAQ. These stations come in real dred more stations since I last wrote Your issue of April, 1924, contains good. I have heard four amateur you. This list may put me on the picture of Thomas ]. Kennedy's set stations this week from th·e states familiar list known as the Dial Twist­ of three-circuit, honey-comb coils. who use microphones. ers. There certainly are some great I use the same circuit and appara­ We had a big storm here a week records on your lists. I have been tus as Mr. Kennedy (detector and ago, and my aerial wire broke into two trying to beat two great rivals of two stages) constructed along similar pieces. I tuned in and heard the fol­ mine, and I am getting closer to them lines, but not the honey-comb coils. lowing stations with the antenna all the time, but they are still far I find that ordinary coils absorb a down: WBZ, WGY, KDKA, W]AR, away. I am not discouraged yet and great deal of moisture from the air. I WHN, which came in with good vol­ expect to beat them if it takes me a would like to suggest that I prove this ume. Freak, wasn't it? year to do it. They are Kenneth by saying that probably the most I am on my set nearly every night Fisher and Curtis Springer of In­ effective test is to place them in an till late, as we are one or two hours dianapolis. I imagine you know them oven for about 15 minutes, letting ahead of you fellows. well, as I saw their wonderful list in them dry thoroughly, and then notice I must say I got my best results one of your issues. My last issue the greater pep they give. ~ out of your wonderful book, which expired with the April number, hut I Winding three on wooden forms usually is a little late, but always is am renew ing my subscription at the 20 inches in diameter and with 35 appreciated. same time I am sending you this. pegs evenly spaced for primary 38 I hope Mr. Kennedy can log the RADIO AGE certainly is a wonderful turns 22; secondary 50 turns, and only two Halifax stations, CHAR and magazine. I like~ it better than any tickler 75 turns evenly spaced, wind­ CHAC o The old DX getter and the of them. ing in one direction every two pegs, RADIO AGE are my standbys. You will notice that I received and hooking them up the same as Wishing your magazine every success, 2KW, E ngland; this being on the honey-combs, has the honey-combs I remain, night of Sunday, March 16, from cheated a thousand different ways, Yours very truly, 12 : 30 p. m. to 12: 50. I received and costs only 35 cents to construct. H . K. HATHAWAY. England weak, but I couldn't get the Mr. Kennedy no doubt has some 441 Brunswic St., name of the station calling them. All remarkable record, but just look at Halifax. N. S. I got was "The Voice of CAPE a few of my long-distance ones on my COD." What station is that; co uld 35 center situated amongst a bunch of By the way, it might be of interest to you tell me? They played the "Pa­ sparks, CW squeaks, howls and street you fans to know that a diagram of the rade of the Wooden Soldiers" and a cars. And I find no diffi culty in bring­ receiver as used by Mr. Kennedy is printed numb@[" of others. I heard the an­ ing them in. i ~ the troubleshooter section. Nuff sed! nouncement and it sounded to me KGO, KGW, KPO, KZN, KFI, something like l XAL. I will give you KH], are the distant ones. My list is RADIO AGE, my list and show some of these too long if I were to put down the Gentlemen: Reinartz and single circuit fans a real nearer distances, and it gets worse A few months ago I sent you a list list to think about. My set is an and worse with respect to length when of stations I had received up to D e­ Atwater-Kent detector and two step. I start to consider local DX. (Local cember 31. Now I will give you a My aerial is one hundred feet long DX is reception of about 200 miles real list that I have received since with a fi fty-foot lead-in. or less.-Dept. Ed~) January 1, 1924. The last fou r I have proof of every station in However, here are some of the sta­ months has been unusually good for case there is any doubt about them. tions I get with great volume regu­ larly: WGR, KDKA, CFCA, CFCF, WLW, WEAF, WHB, WDAP, PWX. I sincerely hope that my list and suggestions will be of value. Yours very truly, S. ]. CRAIG. T 1390 Twelfth Ave., New Westminster, B. C., Canada.

RADIO AGE, Gentlemen: As an American radio fan, living way down east, I like your wonder­ ful magazine; and as I like your book and your drawings of circuits, which - /6-22~ are so simple and plain to everyone, .00025 accept if you please my sincere com­ VERNIER pliments. If everyone goes by your --N motto, they won't go wrong. Your book has been a wonderful help to me. I am using the three honey-comb coil set using two peanut tubes. My set is on the same pattern of Thomas ]. Kennedy's in your April book, and this circuit is surely a DX getter. This is. my list and hope it will make me a Dial Twister-one from "Way Down East," if you please: KDKA, KGO, WGY, WOO, WOR, Figure 2. A diagram of Mr. Williams' receiver. The primary has 77 turns of WIP, WMAF, WBZ, WNAC, WFI, No. 24 Dee on a 4-inch tube, the secondary 70 turns of the same size wire on the . WTAM, WGI, WEAF, WABL, same tube wound in the same direction with 1-inch coupling ; the winding being split WMAK, WGN, WHAZ, WDAR, in the center to allow for the tickler shaft. The tickler has 50 turns of No. 24 Dee WCAP, CHYC, CKAC, CFCF, wire, 25 turns on each side. The secondary should be tapped at the 22ud and 44th WHN, WLAW, WDAP, WMAH, turn. 32 RADIO AGE for June, 1924 The Magazine of the Hour Half of them I received on a loud write to you and give you a log of esting department in RADIO AGE, speaker. what I have gotten out of my set. I am, Sincerely yours, Before reading Baird's letter I had Respectfully, JOHN SABISTON, JR. not thought very much about the per­ GEORGE A. HOLLY. formance of my set. I was perfectly 10214 Adams Ave., Bay Shore, Long Island, N. Y. satisfied with what it was doing and Cleveland, Ohio. Here's the list: getting a lot of enjoyment out of it. After looking over my log I felt like Mr. Holly's list: KDK~K F K~KOB,KO~KS~KYW, writing to John Sabiston and asking P \VX, W AAF, WAAW, WBAH, WBS, wcx KOP, WSAJ, WJAS, KDK I\, WBAV WBZ, WCAE, WCAD, W CAP , for that extra bakelite crepe. I mean WCAE' WEAO WBAV, WKAR, WSAZ. WCllD: w ex, WDAF, WDAP, WDAR, the one he could not use last month. WGR 'WPAll 'WMAK, WSAI, WL\V , WDA Y, WDT, WEAF, WEAN, WFAA, CFCA WHA~i:, WAllC, WBAK, WKC', WFA Y, WFI, WGI, WGR, WGY, WHA ~ I, I think I could present it to my friend WIAr) WFI, WD.\R, WIP, woo, WRAX, WHAS, WHAZ, WHB, WHN, WIP, Baird. A copy of my log is attached; WDAP WJAZ, WMAQ, WCAP, WRC, ""TAR, WJAX, WJZ, WJY, WKAQ, KYW 'WTA Y, WCBD, WHAS, WT AS, WLAG, WLW, WMAF, WMAQ, WNAC, it shows 94 stations. Each one has WaR' WRl\I, \\,GY, WEAl\I, WAAl\I, was, WOAW, wac, woo, WaR, been heard at least two times. I have WH.( WHN, W]Y, WJZ, WEAF, WPAB, WPAH, WPAD, WRC, WSAD, WHAZ WPAH, WllT, wac, WCAZ, WSB, WTAS, WTAM. WSAI, WWJ, 20 more that have been heard only WBZ, \VHAA, WCK, KSD, CFUC, CHYC. WQAM, \VMAK, W CAL, WSY, WIAD, once so they are not entitled to a CKAC, CFCF, WOAN, WEAN. WJAR, WFAR, WPAll, WCE, WHAA, WTAY, WBBF, WSB, WHAT, WNAC, was, WAllT, WllllR, WOAI, WEAY, WGAY, plac~ on my honor list. Stations ~p WSY WMC, WCAL, WOl, WLAG. WJAN, WRAX, WMC, WRM, WQAN, to 100 miles distant can be brought III WDAF WHB KFLZ, W AA W, WOA \\', WMA Y, \VQAE, K~IO , WDAH, WRA Y, KFKB,' WPAK, CKCR, WFAV, KFKX, WWAD WBlle, KZN, KFAF, WRR, almost at will, provided they are on WKY WFAA, WBAP, WWAC, PWX. KFEX, '\VGAG, WDBC, WBL, KFCH, the air and no other station is work­ KDYL, CHllC, CJCA, KHJ .... KFI, CKCD, WT.r\ W , WRK, \VDK, KFKB, KFI, \VWJ, SllZS, SBRK, DJY, StlMK. WCAH, WSAR, WSAG, IXAL, 2BXL, ing on the exact wave. I have a 9XAT, SST, 9ESI, 6KW, SXS, IXAE. 2XZ, verification of reception from nearly 9B M, N RE, N RG, 2KW, KQV, KFGZ, RADIO AGE, KGW, 9CY, WGN, WBAK, WRW, \VGAZ, every station listed. Gentlemen: WJAS, WRAX, WTAN, WJ\IAV, WOQ, In building my set I used the parts WCBR, WFAT, WABL, WSAC, WCAG, The more I read of your magazine, WIAO, WGAW, CHXC, CFAC, CKY, recommended by the Erla people and the more convinced I become that CKCK, CKCH, CJCN, CFCF, CHYC, followed their blue prints to a hair. CHCB, CKAC, CFCA. you have selected the correct slogan. If this is done I cannot see why any­ "Let Our Hookups Be Your Guide." one had trouble with this circuit, but From your October issue I built One hundred and fifty exactly. Not I know a great many have. so bad for four months. What say? "Your First Tube Set" and was very Antenna consists of 30 feet of solid much pleased with the results ob­ No. 12 wire hung in the attic with tained with it. Everything went along RADIO AGE, lead-in taken out of attic window Gentlemen: nicely until WJAZ broadcasting on and dropped down to window in liv­ 448 was changed to WGN, broadcast­ Your seven pages of "pickups" in ing room (17 feet) ground of.No. 12 the March issue of RADIO AGE have ing on 370. Then my troubles began. wire 18 feet long to a water pIpe. It cut me out of WDAP, and there sure made me a Dial Twister fan. I One hundred and twenty volts on have heretofore skipped this section, are parts of their programs which I the plates supplied by a homemade enjoy very much. thinking it to be of no interest to a Edison element B battery. dried up old man nearing the half­ I began at once to look through I am an Erla fan and have built your magazine for help and found way post, but, oh, boy! it's the meat every circuit they have ever devised of the publication; that is, after one your eliminator in the January num­ and have had wonderful results from ber. I constructed this experiment­ has grown weary of trying to build all of them. every new circuit that comes out and ally, mounting it on a pine board, and I would be glad to pass on to fal­ while I know this is not what would settles down to really enjoy radio re­ tering fans what little I know about ception as brought in by a real outfit be termed proper construction, yet these Erla circuits. I am able to cut WGN entirely out that stands weB up toward the top of I do not expect you to give space in the list of consistent receivers. I and listen to WDAP without interfer­ your publication for this long, ram­ ence. Last night when KYW, WGN, refer to the Erla three-tube reflex bling letter, but if you can spare the circuit. and WDAP were going full blast, I time would like to hear from you as eliminated WGN entirely and brought Reading the letter from G. S. Baird, to what you think of the work the in WDKA without any interference. Suffern, New York. and your com­ Erla Triplex is doing for me. I sincerely appreciate the helps ments on same have prompted me to Thanking you for the !llighty inter- which your magazine rendered. Yours very truly, A. C. HART. 2336 Lawrence Ave., THE RADIO I H C Chicago, Illinois. IHC CLUB RADIO CLUe APPLAUSE CARD RADIO AGE, I S COMPOSED OF EMPLOY· Gentlemen: EI'S OF THE INTERNATION· OKLAHOMA CITY. OKLA. In your November issue you gave ...·L HARVESTER COMPANY instructions for the building of the OF AMERICA AT OKLAHOMA AP~ 2. CITY WHO OWN AND OPER· STATION ItAI)'DA(wE'" 1924 old standby, the three-circuit regen­ ATE ~ECEIVING SETS THESE erative receiver. I just happened to YOUR PROGRAM OF EVERy MOHTW-,-__ BROADCAST LISTENERS get a copy of that issue. WANT TO EXPRESS THEIR APPRECIA1 ION OF WORTH · RECEIVED AN{) APPRECIATED BY ME I knew absolutely nothing about WH ILE PROGRAMS THESE TYPE OF ReCEIVING SET YHf( 3 C.I'{~IIIT radio-had hardly seen a set in my CA R DS WILL BE SENT ONLY life, and had never tuned one. So I TO STATIONS BROADCAST­ RECEPTION WAS ENTf.f"s,A.ST'C. ING OUR CONCEPTIONS OF he sitated considerably before I de­ PLEASE T HANK THE ARTISTS CONTRIBUTING HIGH CLASS PROGRAMS cided to build a set. However, the SUCH AS WE WISH TO EN· REMARKS . y()U~ -D/ACrRAMS AND tfOOI:fl!~.s bug had me-so I followed your ia­ COURAGE. THE FACT THAT structions and built the three-circuit. YOU HAVE RECEIVED THIS ARE Tit E aE_~ T t: VE=.!R.=-______~ __ CARD INDICATES OUR AP It was by this time nearly Christ­ PROVAL AND APPRECIATION mas, and it took me some little time OF YOUR PROGRAM SIGNED ' £A~ __ - to get the set to operate properly­ so that I have not actually been using ADQ.RESS BI'?IT TON, .t2./(LA. it very long. Nevertheless, I ~ave Look what RADIO AGE got! In a little while we'll be considered a regular now heard 139 broadcast statIOns, broadcaster-applause cards 'n everything! and am adding new ones regularly. RADIO AGE Jor J une, 1924 The Magazine of the Hour 33 These 139 stations are located in dent backer of the single circuit which was made by myself and a friend. 34 different states, the District of Co­ set. Please consider the much­ I am 12 and he is 14. lumb:a, Mexico, Cuba, and four prov­ so ught-for record of one who oper­ "J ohnny operates under restrictions. inces in Canada. To go into a little ates an old moth-eaten homemade All stations were received before 9 :30 more detail, they are located as fol­ single circuit. Although I have four P. M., as I am not allowed to stay up lows: 1 in Alabama, 3 in Arkansas, tubes, I used but the detec tor tube later. " California 6, also 6 in Colorado, 1 in when I got the following: What surprises the gentle reader is that Arizona, 1 in Florida, 1 in Georgia, WLAG, WCBD, WDAY, WJAZ, Johnny has a list of 73 stations, including a dozen in Illinois, 1 in Indiana, 7 in WOC, WHB, WCAL, WTAS, KDKA. reception from Unite_d States, Canada and Iowa, 6 in Kansas, 1 in Kentucky, 4 KFI, WDAP, KDZR, KFJR, Cuba. Great! in Louisiana, 10 in Missouri, 6 in \VWAE, CFCN, WFAA, KHJ, KPO, Minnesota, 1 in Maryland, S in Mich­ CJCA, KLZ, KJO, CHCE, WBAP. A. P. Smith of R. F. D. No.8, Bangor, igan, 1 in Massachusetts, 1 in Mis­ I used but four and a half hours Me., sends us a letter enclosing a long sissippi (the only one in this state), and quit at 11 :30. The total mileage list of calls heard and wants to be a Dial 8 in Nebraska, 4 in New York, 2 in was between nineteen and twenty Twister. Surenuff. North Dakota, 2 in New Mexico, 1 in thousand miles. How's that for an North Carolina, 1 in New J ersey, 6 in old detector tube under the ideal con­ Mr. Richard H. Starkie sends in a long my home state of Oklahoma, the same ditions of a noisy generator of the list of stations heard on the loud spea k ~r number in Ohio, 1 in Oregon, 4 in local power plant and several other with a single tube reflex circuit. His list Pennsylvania, . 1 in South Dakota. single circuit users? totals 50 stations form every part of the Texas holding the record with 14, 3 in· country. Tennessee, 2 in Wisconsin, and 1 -in Wyoming. This is all-in the U. S., Clarence B. Gannon of 1731 E nsor except 1 in Washington, D. C. Then Street, Baltimore, Md., and Kenneth Glass my records show 1 in Havana, Cuba, Don't fail to m a k e your ,queries and letters conform of 144 South Mount Vernon Avenue, 2 in Mexico City, 2 in Calgary, 1 in Uniontown, Pa., both send in a list of Winnipeg, 1 in Regina, and 1 in To­ w ith the rules published in the suggestions on the Reinartz ' Audio Re­ ronto, these last five being Canadian May, 1924, Troubleshooter sec­ generator, which we will present in next stations. . tion. There is no excuse for month's Pickup pages. They certainly How's that for a log over the time not complying with rules such are appreciate, but due to the fact that I have been using my set? Oh, by as were found necessary to as­ they came in just as we are about to go the way, I forgot to tell you that I sure all our readers an equal to press with this issue, we could not am a traveling man, and am away chance of this service. print them. from home about half the time. We have a number of ques- I 'I don't claim to be an expert as yet tions on hand at present that E. Brandt Boylan of 1106 West Eighth in the operation of a set, but I'll Street, Wilmington, DeL, "The First City have not been answered be­ of the First State," sends in a list of undertake to tune in anyone of forty cause their writers did not ob­ or fifty of the principal stations in great length compiled from receptions on the country as quickly as anyone. My serve the rules as they were a Bachm an single circuit rece iver. He record. for one evening is forty sta­ specified. Due to the g rea t has several 2.000-mile receptions to his tions, 29 of them less than a thou­ number of questions we re­ credit. FB OM! sand miles di stant- and these over a ceive, ~ his has been found nec­ thousand miles away: WGY, Sche­ essary, in order that justice To conclude this month's Pickup Sec­ nectady, 1,375 miles; PWX, Havana, may be done to all of t~1em. tion, we print this letter from a Califor­ 1,225 mil~s; KDKA, Pittsburgh (no t If you don't know what w e nia fan who must be living near some movie lot where they make comedies. re-broadcast from Hastings), 1,050 are referring to, read the notice miles; KFI, Los Angeles, 1,200 published on page 42, Trouble­ RADIO AGE, miles; KHJ, Los Angeles, i ,200 Gentlemen: miles; KPO, San Francisco, 1,410 shooter section of the May, First of all I want to tell yo u that miles; KGO, Oakland, 1,4 10 mi les; 1924, issue. most radio magazines are NG. Savvy? KLX, Oakland, 1,410 mil es; CFCN, Technical Editor. For instance- a hookup form (name Calgary, 1,375 miles; WCAE, Pitts­ of magazine upon request) knocked burg, 1,050 miles, and KGW, Port­ my tube colder than King Tut's land, 1,5 10 miles. Portland is gen­ grand-dad, and also gave my ears a erally regarded as a "dead spot" here, This all happened on the night of vacation. Another hookup from the very few ever hearing them. I for­ January 20, a Sun day night at that. same magazine made me think my got to try, or I could have added Very truly yours, antenna had fallen on a trolley wire; KFSC; at Los Angeles to the above CARLOS W. NESTLER. in fact, my phones were doing a 1021 list. Flaxton,.N. D. shimmy, and danced around I:ke Does this let me in to the "Dial Indian clubs. Twisters"-or do you want more? Mr. James P. Cooper of Memphis, Yes, ma'am-they sure did have I can very easily better this night's Tenn. , care of Southland Cotton Com­ chills. Tust as I was about to take perf ormance. pany, writes of his experiences with a the axe 'and make my radio set look Sincerely, Cockaday set, and tells how he learned to like the ZR-2 wreck, with the excep­ T. W. ROBINSON. operate the set so as to get a list as lon e: tion of the Japanese earthquake. a Brittol~, Ok'a. as a music roll. He also says he picked thought came to me, saying: "Stuy up 13 stations in 39 minutes, or a station at it ulltil you do get a good set." RADIO AGE, every three minutes. Some speed! All right, I says to myself, I'll do Gentlemen: it! So [ grabbed my hat, and started I am an ard::: nt reader of your Ray Ellis of Durand, Ia., Ccdar County, fo r a magazine and book store, hitting good magazine and am very desirous writes of his success wi th the Rcinartz, on all two; got there in ten minutes, of becoming a Dial Twister. I on­ and states: "The Reinartz hookup means just before closing time, (1 o'clock, ticed th~ t you have published several to the broadcast li stener more volume, and purchased a magazine I had ne\'er records of some fans who operate greater di stance, and wo nderful selec­ heard of before-RADIO AGE! three-tube, three-circuit sets and who tivity." I rushed back home, as I knew it I think ought to be eliminated en­ was silent night for Los Angeles, tire ly because anyone with such a set John Escher of Sprin g Lane. Englewood, hooked up yo ur Roses-in-bloom cir­ ought to consider the records that ]\,". J., says: "I am sending yo u a log of cuit, only to find that my A battery they send in very poor. I am an ar- stat:Ol:s heard on a se t (single circuit) (Collti/wed all pal!,c 53.) 34 RADIO AGE for June, 1924 The Alagazine of the Hour . PMGL By THE TECHNICAL ASSISTANT

EGULAR readers of this magazine, frain from using the oil to wipe the excess cranky as mentioned before. Now take when referring to circuit diagrams, dust off. ' the pencil and draw a firm line between R no doubt have noticed the letters the two edges of pencil mark sticking out­ P MGL next to the zig-zag line denoting Good Contacts Essential side of the tinfoil washer. The action the grid leak, and without question they Drill two holes to fit the type of ma­ of the set will be very much different. wonder what this means. It has probably chine screws you intend to use; the size is Experiment by making the mark a little been given different names to suit the let­ not important. After this has been done, heavier, ahd you will soon find the point tering, but the matter stands that it is take a good soft pencil, a No.2 or B is where the tube settles down to business very important. satisfactory, and make a good heavy and operates at maximum effectiveness. There are, perhaps no other units in the smudge of pencil lead around the hole Too much leak will cause the set to oscil­ receiver that make more trouble, noises made for the machine screw, enough to late too readily, giving the operator the and are given less attention than the grid allow a good margin around a tinfoil impression that it is very sensitive, when leak and condenser. Just because an ex­ washer. Rub the lead good and hard, and it is really dead. In either case, the leak perimenter can wander into most any radio let it be big enough to come out around is adjusted by lowering the resistance or store and purchase something that mas­ the washer a considerable distance- Ys raising it until best action is obtained. querades under the title of grid leak, it inch is not too much. Do this for each Incidentally, some of the C300 or UV200 does not mean that this little unit is not side as illustrated. Now place a soldering tubes often function without a leak at all. important. The sooner the DX "fan" lug and a tinfoil washer on the machine The other high vacuum valves invariably finds out that the grid leak is one of the screw, and insert the screw into the hole. require leaks. factors in the success or failure of his re­ Tighten down the hole unit good, making ceiver to be sensitive, the more distance sure that good contact is made. Adjustable Leaks his set will cover. Connect the wires by soldering them Adjustable leaks are very handy and A good grid leak must have the right to the lugs as furnished. Be careful not convenient if they are so constructed that resistance for the type of tube used, must to let the flux, rosin or whatever agent you they hold their values. If this is not 50, not assume different values with different are using for soldering run on to the the leak will have to be tinkered with con­ weather conditions, and must make good grained strip. Turn on the tubes and plug stantly. Some of these leaks fit the usual contact. So simple that it is considered the phones on the detector stage. The set clips, and others are so designed to mount unimportant. will very likely be cranky and unstable, on a panel. Personally, the writer finds Pmgl will howl and squawk at the least touch, that the panel mounting types nearly always cause trouble in the hands of be­ The pencil mark grid leak is probably and · ,vill give weak and wheezy signals. ginners, because they mount them too the most simple and effective type on the This is, of course, only when the grid wires close to other units, binding posts and market- if it is properly constructed. A are so arranged that they do not touch parts. Also, it is not good design to run leak of this type is illustrated in Figure 1, the panel or mounting board or any part wires of the grid circuit near to the panel, and consists of nothing more than a strip of the cabinet. as hand capacity and critical tuning is of insulating material with a pencil mark One can classify this matter as a sort nearly always the result. The grid leak drawn between two good contacts-hence of unintentional grid leak, and the symp­ in connection with the grid condenser the name " Pencil Mark Grid Leak." toms are that the leak, when connected should be mounted directly on the G post When making a leak of this kind, do not and adjusted, has no effect upon the action of the tube socket, which should be of use a fiber, paper or cardboard strip. of the tube. This means that the tube good hard rubber, porcelain, pyrex or T hese things are useless, because they soak socket is poor, the grid wire is touching other insulator of high dielectric strength. up moisture in wet weather, and every something that is causing the trouble, the panel is bad or that the grid condenser Mouht them as close as you can mechan­ time it gets damp the leak absorbs mois­ ically. The reward comes later in the ture and you have two grid leaks instead is faulty. Be cautious about buying form of steady signals. of one. The moisture furnishes one re­ moulded mud grid leak mountings, as they si~ta n ce, and the pencil mark another, with often are grid leaks in themselves and Noises the result that the set is unstable, finicky, defeat the purpose of the one you are seeking to adjust. Noises in sets can often be traced to and hard to tune, often fails to stop oscil­ , poor contact in grid leaks and grid con­ lating, and many other disagreeable ex­ Adjusting densers. If this happens to a sealed-in periences are encountered. glass tube leak- throw it away, and use a Adjusting the grid leak of the pencil Procure a piec e of hard rubber or a new one. However, before you discard mark type is very simple. The leak is strip of bakelite-dilecto about 1 il4 or 2 the unit make positive that the trouble connected in the regular manner across inches long and 0 to Y

Figure 1. An easily constrllcted vari­ able grid leak that gives good results. The ,q::NCIL 10k is adjusted by making a m ark be­ Bl..08-~~- tween two contacts, the size of the m ark and the heaviness determining the resist­ ance. If the valne is too low, m ore pencil should be applied ,. if it is too high, it can be lowered by erasing it lightly with a pencil eraser. H,4QDRlIBBER De BAkEL-ITe LEAk. NUT lS.- BOLT RADIO AGE for June, 1924 The Afagazine of the H our 35

HereJs the Best Hookup Book Ever Printed!

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R ADIO AC I:: , In c., 500 N. Dearborn St., Chicago, III. Gentle men: Altached find One Dollar ($1) for which Detach this Coupon, fill in, pin kindly forwa rd me hy return mail one copy of RADIO AGE ANNUAL FOR 1924. If not satisfied with it a Dollar Bill to it and mail I will return it lo you within lhree days a nd you will TODAY! refund 11I y mOlley . Name, ......

If Paying by Check Add 5 Cents for Exchange, Address, " .. . , . .. , ......

City , , ...... " . . ... State ...... 36 RADIO AGE f or June, 1924 The Magazine of the Hour

Kadel & Herbert Foto RADIO REPLACES SCHOOL TEACHERS The experiment of teaching school children by means of lectures broadcast has been inaugurated by the London County Council and a loud speaker installed in many schools in London. The first lecture was broadcast by Sir Wal­ ford Davies on "Musical Appreciation." Photo shows pupils at the Hugh Wyddleton School listening to the lecture.

Just because you have a good grid leak, Important Super-Heterodyne the winding space is short. In any case don't think you can use any makeshift for the tap is taken from the center of the a grid condenser-and yet expect the set Factors coil. to work decently. It won't do. Use a (Conti1lued from page 7.) If the tube happens to be 4 inches in good sealed-in mica condenser, tested to diameter, then it may be wound with 36 the capacity you want, and avoiq the use is found in the same way. The highest turns of No. 18, 33 turns of No. 20, or of paper or other contrivance that radio of the normal broadcast waves will not be with 30 turns of No. 22. As mentioned t ngineers classify as "Gyp" stuff. over 600 meters. This will have a fre­ before, the rotor has only '8 turns of No. quency of SOO,OOO cycles. There is a 18 regardless of the size of the tube. General Suggestions difference between this and the 100,000 To wind the tube for a 6,000 meter Don't expect your set to work decently cycles of the intermediate frequency intermediate wave use 42 turns of No. 18 with a thin layer of soldering flux all over cmounting to 400,000 cycles, which is it it is a 3-inch tube, or 39 turns of No. the parts. They are grid leaks and cut equal to a 7 SO meter wave. By this 20, or 33 turns of No. 22. If a 4-inch down your efficiency. Inspect the leak and method, the range required for the oscil­ tube is used, either 29 turns of No. )8, condenser often, because even the best lator is obtained, and in a like manner 26 turns of No. 20, or 23 turns of No. 22. parts go wrong occasionally. Avoid the use the range of the oscillator required for .For use with a 10,000 meter intermediate of carbon paper grid leaks. If you use the other intermediate frequencies is obtained. wave, wind the 3-inch tube with 36 turns cartridge types, get a whole set of them The most simple oscillator for the of No. 18, 34 turns of No. 20, or 30 from .S megohm all the way up to 10 novice to make is that designed by Hart­ turns of No. 22. If the tube has a diam­ megohms. Try them all out on the tube ley, the circuit of which is shown in Fig­ eter of 4 inches, it may be wound with 28 until you find the best one. Some leaks ure 2. It can be made by taking an turns of No. 18, 23 turns of No. 20, or 21 have a metal seal end, with metal dust ordinary vario-coupler and stripping it of turns of No. 22. These specifications will fl ashed on the inside, and then sealed. all the windings. The size of the tube give a fairly wide range of variation to Such leaks are almost always good. The will, however, have much to do with the suit the particular size of coupler used. gl ass sealed type with the carbon paper winding required, so that several specifica­ From the pickup coil, the combination lpak are more apt to be defective, as only tions will have to be given in order that wave is passed on to the grid of the first too often they are carelessly assembled one may adapt·a coupler of any size to the detector tube. This, however, should not and absolutely "N G" for radio work. purpose. The rotor is to be used for the confuse the reader, who will probably Last but not least, after you've found pickup coil, but in any case the winding wonder why it is necessary to use two the right resistance, leave it alone. Don't "ill be the same. Eight turns of No. 18 detector tubes in the super-heterodyne be nervous and continually "hike" the double silk insulated wire should be used. circuit, but the reason for this is that the leak. You will always end up where you For the 3,000 meter intermediate wave, first detector is used in the transforma­ started, and often a good adjustment is the windings should be as follows: If the tion of the frequency while it is still above lost by not refraining from tinkering. tube is 3 inciles in diameter, with plenty audibility, and a second detector is neces­ of winding space, it may be wound with sary to bring it down to audibility. Audio Amplification 49 turns of No. 18 double silk insulated Three stages of resistance-coupled am­ wire. This will require approximately plifi cation should give sli ghtly greater 2o/Ir, inches of winding space and the tap SPECIAL FOR JUNE amplification than a two-stage trans­ is taken out at the 2 Sth turn. It may The Reinartz Radio Booklet, by Frank D. Pearne, fully illustrated, and RADIO AGE, former-coupled amplifie r. The quality, of also be wound with 48 turns of No. 20 for $2.50. Price of booklet alone is SOc. Send course, will be much better. The B bat­ wire, in which case the winding space will check, currency or money order to RADIO tery voltages, except on the detector, have to be 1:r4 inches. It may also be AGE, 500 N. Dearborn Street, Chicago. should be from 90 to 180 volts. wound with 42 turns of No. 22 wire, if ------~------~------~-----

~ o 0 o o V o...... ~ () CONSTRUCTION NOTES (5·30·10) INDUCTANCES (F·2·1) lTJ ~ WIRING AND CONNECTIONS INDUCTANCE AND FREQUENCY "': '--< C ::l I'D "A" BATTERY LINES. The following notes apply to connections made in the filament circuit such WAVE LENGTH AND FREQUENCY. A radio wave travels forward at a velocity of 300.000.000 as connections to filament rheostats, to the "A" battery, sockets, etc. In making these connections care meters per second, or approximately 186.000 miles per ~econd. This velocity of translation is approx­ ;-. should be observed in having the correct polarity at all points. imately the same as for light waves. At the same time, the wave is subjected to a series of vibration so \Q that the intensity of the wave is continually varyil1g during this time. The rate of vibration or oscillation N is determined by the characteristics of the circuit constants of the transmitting station and may range from ~ (1) Rheostat should be in negative line (-A) or (-F) for both detector and amplifier tu?es. 100 to 2.000,000 complete cydes per second in ordinary circuits. The rate of vibration or oscillation is known as the "frequency" of the wave.

(2) While the polarity of the two posts marked (+F) and (-F) on the sockets is not of actual im- " portance, yet the connections should be made to the posts with the proper polarity in order to have a system­ In one second the wave travels a distance of 300.000.000 meters, and if the complete number 01 out and atic arrangement if nothing else. back oscillations (cycles) during this time are 300.000, then the distance between the centers of the peaks of the waves will be equal to the total dista nce divided by the number of double vibrations. This cPnter to center distance between waves of like direction is called the " \Vavelength" of the system and is totally (3) Be sure that the rheostat has the proper resistance for the tube used. If the resistance is too dependent upon the frequency. Thus. high or too low, then the proper filament control will not be had. 300.000.000 WAVE LENGTH IN i'.IETERS=-----=1.000meters. (4) At points where the ( -A) and (-B) connections come on one post or on two directly connected 300.000 binding posts, place the b3.tlery cutout switch in the (-A -B) lead rather than in the positive "A" (+A) In the "iorm of a general rule for any frequency, this can b.' :l tated as follows: line. If this is done, then both the "A" battery and "B" battery will be cut out when the switch is opened a nd the le3.k3.ge of "B" battery current will thus be avoided when the line is idlt'. 300.000,000 WAVE LENGTH IN METERS = ----­ Cyries pe r Sec. (5) Be sure that the rheostat binding posts are tight and are making good CO'ltact with the coil Or in the reverse sense we can obtain (he frequency from the wave length by; before making connections to the rheostats. Also make sure that the binding POStS on the socket are tight and that the spring clips in the socket a re not loose. 300.000.000 CYCLES PER SECOND =----­ \Vave Lgth. (6) Adjust contact fingers of rheostats and potentiometers to the proper tension before wiring, and see tha t the contact finger makes proper contact with the coil in all positions. Adjustment of this part is difficult after the set is wired up. It is profitable to note that the product of the wave length in meters by the frequency in cyclt's per second is always equal to 300.000,000. This fact gives us a check on our calculations. KILOCYCLES. As the usual broadcasting wave lengths are in the nature of 500.000 to 1.000.000 (7) As the rheostats and "A" battery lines are generally inaccessible on most sets after wiring, these cycles per second, the term "cycle" is too small to be handled convenie!,tly, hence we frequently see the parts should be mounted on the panel and completely wired before tht' other parts a re installed. . term "Kilocycle" used. A kilocycle =1.000 cycles per second, hence the term 600 kilocycles means the same thing as 600.000 cycles per second. "3 ~ (8) Tube sockets should be mounted on rubber or felt cllshions before wiring so that vibration will ~ not cause the ringing bell like noises known as "microphonic noises." Particular c.ue should be taken with WAVE LENGTH AND INDUCTANCE. The use of inductances, or combinations of inductances dry cell tubes as these are generally strongly microphonic. and condensers. gives us a means of bringing our receiving sets into resonance or into step with a trans­ mitting station. or'a means of rejecting certain stations which we do not care to hear. At the transmitting ~ station. the use of inductances a nd condensers allows the station to send out waves of a given frequency. ,,<:> (9) Use only heavy bus wire lor tne fila ment or "A" battery wiring since these lines carry com­ paratively heavy currents. No. 14 bare tinned copper bus wire Is the smallest that should be used. .,..~ . Each inductance has a natural wave length or natural period of oscillation which may be increased ;:: or decreased by adding or subtracting turns of wire or by the use of condensers applied in parallel or in C'> (10) \Vherever possible use solder lugs at the points of connection and solder the wires firmly to the series with tht' inducta nces. The maximum flow of current through an inductance takes place when the lugs. \Vires fastened only under binding screws are likely to loosen or corrode. - ~ inductance is so adjusted that it is in resonance or in step with the incoming radio impulses. This adjust­ .,." ment is commonly known a s "tuning" and affords a means of receiving or rejecting stations operating ~ (11) \Vires should be well supported so that they cannot sag and come into contact with one another, at various wave lengths or frequencies. CI> thus forming short circuits. In the calculation of inductances which are to cover a certain band of wave lengths. it is more con­ ~ (12 ) Use spa~hetti on the " A " battery wiring where considt'red necessary as a protection against venient to use the frequency in terms of cycles per second than to use the wa\'€' length in meters. For this ~ short circuits, but leave it off on the lines which carry radio frequency currents as the spaghetti increases reason. when the frequency is given in meters of wave length. we must convert the wave length into terms "': the distributed capacity. of cycles per second by the above formula before proceeding with the calculation of the inductance.

CN COPYRIGHT 1924 CO:\IPILED BY COPYRIGHT 1914 COMPILED BY "-l RADIO AGE J. B. RA.THBUN S-30-10 RADIO AGE J. B. RATHBUN F-2-1

,! 38 RADIO AGE for June, 1924 The jl,Iagazine of the HOllr Radio Will Not Be Taxed Storm of Protest Defeats Senate Radio Tax

ADIO is tax-free! The first at­ 10. Radio receiving sets, 10 per A fund to help fight the tax was sub­ tempt to place a federal tax on cent. scribed to liberally by the radio jobbers. R radio, which originated in the 11. Parts and access ories for radio The Radio Deals Inc., an organization United States Senate with the proposal receiving sets, sold, or leased to any with more than 100 members among the that a 10 per cent excise tax be levied on person other than a manufacturer or trade, went on record as opposed to the radio sets, parts and accessories, has been producer of such sets, 10 per cent. tax. The Radio Trade Association, the defeated after the greatest storm of public Radio Chamber of Commerce, the Radio protest America has ever known. As soon as the proposal was made pub- :Manufact urers of New Jersey, the Cleve­ The amateur radio " fan" was sponsored lic, public sentiment rose immediately and land Radio Dealers' Association, the Pa­ by virtually every force in the radio in­ set out to kill the radio clause in the rev­ cific Radio Trade Association, the Atlanta dustry in his fight to make radio goods enue bill. Senator C. C. Dill championed Radio Trade Association and the Ken­ free from taxation of any kind. The the fans ' cause in the Senate and ar­ tucky Radio Trade Association are but a United States Senate was literally flooded ranged for the various petitioners to ap­ few of the jobbers' and manufacturers' with literature and delegations protesting pear before the upper house of Congress organizations who made their influence against the suggested "harnessing of to present their arguments. felt in Washington. American inventive genius." The press, radio publications as well More than 50,000 circulars were dis­ as newspapers, combined with the broad­ tributed to dealers and jobbers by the Starts In Senate casters and manufacturers to fight the Radio Trade Association of New York. The proposed tax on radio was not radio tax. Members of the House of Rep­ A steady stream of telegrams from fans contained in the revenue bill as it came resentatives asserted they would do all in throughout the country pledged support from the House of Representatives, but their power to kill the proposal in the to the campaign. was inserted by the Senate committee on event it was passed by the Senate. The Talking Machine and Radio Men, finance. The principal clause was Section Inc., an organization of music producers 700 of "Excise Taxes," which read: Public Sentiment Wins and manufacturers, went on record against Public opinion was so strong, however, the tax. The National Association of SEC. 700. On and after the expira­ that the radio excise tax died in the Sen­ Broadcasters helped to furnish the public tion of thirty days after enactment of ate itself, thus assuring radio from federal and the newspapers with the fans' and t his Act there shall be levied, as­ levy f.or at least two years. broadcasters' reasons for opposing the tax. sessed, collected and paid upon the The entire radio field stood solidly be­ following articles sold or leased by the hind the amateur radio owner in his fight Dill Boosts Cause manufacturer, producer or importer, against the tax. At a meeting of metro­ Senator Dill. after furnishing the Senate a tax equivalent to the following per­ politan jobbers of radio products, held in finance committee with the public's peti­ centage of the price for which so sold New York, more than thirty jobbers tions, introduced an amendment to the or leased. pledged their support to the campaign. (Col1til1ued on page 40)

THE " LEVIATHAN OF RADIO" Charles Caesar Ritz, of Forest Hills, Long Island, receives San Francisco and other California stations on the loud speaker of his four stage tuned radio frequency set with amazing clearness. Mr. Ritz, who is the son of Caesar Ritz, founder of the chain of Ritz-Carlton Hotels, builds all of his own equipment. The set shown in the photo is radically different in design and can be operated entirely as a four stage neutrodyne set or four staged tuned radio frequency set. This is quite an achievement, as it is considered virtually impossible to use more than two stages in a neutrodyne type receiver. Mr. Ritz has found that when he uses the set as straight tuned radio tuned frequency it is more selective and sensitive than when it is used as a neutrodyne. Eight tubes in all are used; four for radio frequency, one for detector and three for push-pull power amplifier. ---____ ~_~~· __ ~~ ______c ______~ __ ~ ______- ______~~~ _____ cm._= __ =~_.~ __ ~ ___ .= __ •• ______._ ••• __ _

>~ o o o o .....tJ '.,I""' >­ CJ VACUUM TUBES (JJ·9·27) VACUUM TUBES (JJ·9·30) ~ ~ OPERATING CHARACTERISTICS OPERATING CHARACTERISTICS ~ c­ C ::l .!1> AUDIO BIASING VOLTAGES. In the following table are shown the proper negative biasing BIASING AND PLATE CURRENT. The plate current taken by the various tubes depends upon voltages for audio amplification for a given plate or " B" battery voltage. The biasing voltage is th ~ voltage the plate voltage and the degree of bias placed on the grids. and whether this bias is of a positive g r negative \0 of the "C" battery in the grid circuit. and the values shown produce maximum amplification with a minimum potential. A positive (+) bias is ordinarily necessary with a detector tube and causes a considerable N -,j::o. of distortion for the various classes of tubes listed. current to flow. b ut in a udio amplification circuits. super-regenerative circuits and a few other types. the use of a negative bias will greatly reduce the flow of plate current and will therefore greatly increase the life of the "B" battery. BIASING VOLTAGES FOR AUDIO AMPLIFICATION In the following table. we have figures that apply to tubes operating u'nder different degrees of bias. PLATE BIAS OR NO. OF The flow of plate current is given in terms of "milliamperes" 01' thousandths of an ampere. TYPE OF TUBE VOLTS "C" VOLTS DRY CELLS U\,-20IA. C·301.o\ ...... 40 ...... 0.5-0.75 ...... DETECTOR TUBE PLATE CURRENT ...... 45 0.7-0.9 FILAMENT TUBE "H" VOLTS "C" VOLTS PLATE CURRENT CURRENT 50 1.0-1.5 NAME (PLATE) (BIAS) MILLIAMPERES (A MPERES) 60 ...... 1.5-2.0 I' UV-199 ...... 22.5 ...... + 1 ...... 0.60 ...... "., .0.06 67.5 ...... 2.0-3.0 1 to 2 C-299 ...... : ...... 45 ...... + 1 ...... 1.65 ...... 0.06 ...... 75 3.0-4.0 2 to :3 g~~OO? .. :::::::::::::::: ~~:t: :: ::: :::::: : tt :::::::::::::: g:n :: ::::::::::: ~:::: ~:gg 80 4.0-4.5 3 UV-201...... 22.5 ...... + 1 ...... 0.60 ...... 1.00 ...... 90 4.5-5 .0 3 to 4 C-301...... , 45 ...... +1 ...... 1.80 ...... 1.00 5.0.6.0 UV-20IA ...... 22 .5 ...... + 1 ...... 0.50 ...... 0.25 ...... " ...... , ..... 100 3 to 4 C-301A ...... 45 ...... + 1 ...... 2.00 ...... 0.25 ...... 11 2.5 ...... , 6.0-7.5 4 to 5 WO-11 ...... 22.5 ...... +1 ...... 0.70 ...... 0.2-" ...... 120 6.0-9.0 ...... 4 to 6 \¥0-12 ...... 45 ...... +1 ...... 1.75 ...... 0.25 UV-1 99. C-299 ...... 40 0 . .1-0.75 ...... •...... 1 .... '" ...... , ...... 45 0.7-0.9 ... , ...... 1 AUDIO AMPLIFIER PLATE CURRENT •••••.••••...•••.•..•••.•• SO 1.0-1.5 UV-199 ...... 45 .0 ...... 0 1.40 1.5-2.0 C-299 ...... , 67.5 ...... 0 ...... 2.40 60 ...... 67.5 ...... -3 ...... I.RO · ...... 6·7.5 ...... 2.0- ~.O ...... 90.0...... 0 ...... 4.00 · ...... 75 ...... 3.0-4.0 2 to 3 ... , ...... 90.0 ...... -4.5 ...... 2.25 · ...... 80 ...... 4.0-4.5 UV-201 ...... 45.0...... 0.0...... 1.50 3 C-301 ...... , ... 67.5 ...... 0.0 ...... 2.50 ...... 90 ...... 4.:;-5.0 3 to 4 ~ · ...... 100 ...... 5.0·6.0 4 .. :: : : : :: : : : : : : : : :: : :: g~t :::::::::::: : -gt :: : : : : : : : : : :: t~g C\) WO-l1. WO-12. C-11. C-12 ...... 45 ...... 0.0-0.0 None ...... 90.0 ...... -4.5 ...... 2. 10 UV-201:\ ...... 45.0 ., ...... 0.0 ...... 1.50 50 ...... 0.5·0.8 1 C-30IA ...... 45.0 ...... -1.5 ...... 1.10 · ...... 60 ...... 1.0-1.5 · ...... " 67.5...... 0.0...... 3.50 Irq~ ...... 67.5 ...... -3.0 ...... 1.90 >:l · ...... 67.5 ...... 1.5-2.0 I to 2 i>'l · ...... 80 ...... 2.0-3.0 2 · ...... , 90.0 ...... 0.0...... 6.00 ... · ...... 90.0 ...... -4.5 ...... 2.00 ~ ...... 90 ...... 3.0 2 WD- ll ...... 45.0...... 0.0 ...... 1.50 (';, \VE 216-:\ ...... , ...... 45 ...... 1.0-1.5 WD-12 ...... 45.0 ...... -1.5 ...... 1.10 ...... " .. , 67.5 ...... 3.0-3.5 2 to 3 ...... 67.5 ...... 0.0 ...... 2.50 ~ ...... 90 ...... 4 ..'i-6.0 3 to 4 .. .' ...... 67 .S ...... -3.0 ...... 1.60 ;:;;:...... 112.5 ...... '" ...... 6.0-7.5 4 to 5 · ...... " 90.0...... 0.0...... 4.50 ~ · ...... 90.0 ...... : -4.5 ...... 2.50 ...... 150 ...... 12 .0 8 216-A ...... 120.0 ...... 0.0 ...... 13.80 Q:: \VE-VT-2 ...... , ., ., ...... '" 90 ...... 4.5-6.0 ...... 3 to 4 ...... 120.0 ...... -9.0 ...... 7.50 ~ " ...... 150 ...... 12.0 ...... 8 <:: ...... , .... , .. , .. 200 ...... 22.5 ...... 15 The effpct of a ne!{ative bias on the UV-201A or C-301A is ver}' pronounced, as with a bias of -4.5 ~ . ..•.•...... ' .' .350 ...... 40.0 ...... 28 volts, the tube only takes one-third the plate current taken with zero bias •

COPYRIGHT 1924 COMPILED BY COPYRIGHT 1924 COMPILED BY W RADIO AGE J. B. RATHBUN J J-9-27 RADIO AGE J. B. RATHBUN JJ-9-30 IQ 40 RADIO AGE for June, 1924 The Magazine of the Hour

( Contillued from page 38) Emergency Radio Tax Committee of New radio business," he said. I consider radio re\,enue bill cancelling the 10 per cent tax. York, reported that "immediate, spontane­ the greatest discovery of the age and one This amendment prevented a summary ous hostility to the public has been ex­ which is bringing pleasure to untold mil­ approval by the Senate and caused the pressed by letters, telegrams and editorials lions of people." radio provision to be subjected to open throughout the country. There has been debate. no favorable expression of opinion regard­ World Metric Standards A nation-wide appeal to amateurs inter­ ing the radio tax. The only argument Adoption of metric units of weights ested in radio to join the fight on the tax advanced for the tax is that the money and measures in merchandising will be a was sent out by the American Radio Re­ must be raised somehow. timely topic of discussion before the great lay League through Hiram Percy Maxim, "Against this, criticism is expressed convention of the Chamber of Commerce president of the organization. everywhere against imposing this tax on of the United States, to be held at Cleve­ The American Radio Relay League has an industry just struggling to its feet, with land in May. On May 5th the metric a membership of 16,000 amateurs through­ an enormous amount of development and issue will be prominent, the national coun­ out the country. These amateurs own standardization confronting it and no so­ cil being called upon to advise whether low power transmission and receiving sets lution yet offered for the great problem the pending Metric Referendum shall be which they use to pick up and relay non­ of broadcasting. submitted to nationwide vote of American commercial messages. Tax Would Raise Prices business organizations. "A proposal to tax radio is an effort A year of study and conference was to levy a financial burden on the amateur "Such a tax would have an adverse devoted to world standardization by the inventive genius of this country," Mr. effect on the tendency to improve product Metric Committee of the Chamber of Maxim asserted. "Radio owes much of and reduce prices; a most deplorable con­ Commerce of the United States, and the its development to the research work that dition, especially because the manufac­ report of this group will be the basis of has been done by the young men of the turers could not absorb the taxes, which the vote. Already the national council is nation. Radio has probably done more would then have to be passed on to the on record in favor of sympathetic con­ than any other agency for keeping boys consumer with all the intermediate in­ sideration of the metric advance, and it at home. It has stimulated imagination, creases inevitable in such a process. is believed that the Referendum will be tbought and scientific effort. "There is also a general impression called forthwith. that by resisting this new nuisance tax A Needless Tax the people will hasten the final elimination Wendell Hall on Mardi Gras "Why should we needlessly cripple it? of existing nuisance taxes. Radio has been From WLS The Radio Relay League does not believe developed and perfected largely by the in­ Wendell Hall, the traveling radio trou­ that any such se rvice should be taxed ventions of amateurs. badour, and the Cambridge Sisters, the without need. The educational opportuni­ " By placing burdens on these amateurs, divine trio of harmony, featured the Her­ ties of radio should be stimulated instead the government will actually be taxing ald and Examiner's Midnight Mardi Gras of handicapped. We don't tax schools American inventive genius." from WLS recently. Hall, the famous and colleges in this fashion, so why should Senator William S. McKinley from Illi­ "red-headed musicmaker," sang, among we tax this newest and greatest of educa­ nois oppose d the tax in a statement to the others, his own "Dear Heart of Mine," tional agencies?" Radio Trade Association: "Shattered Dreams" and "If I Only William P. Davis, chairman of the "I am opposed to the taxation of the Knew. " GENUINE, STANDARD, SEND NO MONEY SYNCHRONIZED WE SHIP C. O. D. LICENSED HAZELTINE

BUILD WRITTEN THIS MONEY -BACK GUARANTEE FAMOUS 5 TUBE KIT Complete Quick Assembly Outfit of Synchro­ n ized Receiving Set to Reach From Coast to Coast With Amazing Selectivity and Clarity Read These Letters From Enthusiastic Fans WRITTEN Money-Back Guarantee. This is the amazing set selling hy thou sands all over Am e rica. No radio knowledge needed. no skiIJ w ith tool s. no experience. Everyone instantly nnde r­ ~ta nds ou r extra complete ip. 5tru (. tion s and s imple. clear blueprint -.-,,, LOOK AT THIS diagram. Tust 2 or 3 hours fa scina ting fun builds your set. You ~MAP SENT IN can' t go w rong. You get the big broadca , ting statIOn s. Extraor­ dinary long di st a nce from Coast to Coast is easy. Only the best "From Clawson. I\1:ichigan, ; n this set- ALL genu ine STAN DARD N EUT RODYNE pa rts I get from Coa st t o Coast on LICENSE D under the original HAZELTI NE paten ts a nd guaran- m y horn. including HONO­ L ULU. HAWAII. on the night K\ :~T~H~De roerrft~ta ~;i~~ \t sa ~gga rsaa~~~ ~ ac ¥~~. f ~~tO ;"sll t~~ rt~a ~d: of March 21. a t 2:05 A. 1\1." somest ever made, reproducing fine mahogany, with ever y mark­ -Da le Jenkins . Clawson. Mich. ing eng ra ved in GOLD. A magnificent ornam ent. A pe r f~ct . highest g racle. efficient. powerful inst rument tha t you ca nnot "I cong ratulate you on giv­ dupilca te for THREE T J]\IES THE P RICE . ing the radio fans these won­ derful hargains." WHAT THIS GENUINE STANDARD SET CONSISTS OF- - A. J. T oll. 742 Nelson St .• 1 Drilled R adion Mahoga nit e Panel. like mahogany. engraved in London. Ont.. Can. gold: 3 4-inch Radion Mahoga nit e Dial s. gold engraved; 2 gold­ plated J ack s : 3 genuine H azeltine N eu t ro formers mounted on "I would have had to pay the fa mous Com sco Ba kelite E nd Co ndensers (positively the three times your price out only Neutrodyne Kit including these fa mous Com sco Condens­ here for the same parts I er s); 2 n azeltine N eutrodons : 5 Bak eli te Sock et s : 1 6-ohm bought so low fr om you." Rheostat a nd I 30-ohm R heostat with gold-pla t ed k nohs to - Stephen Vandrey. 52C 16th m a tch panel; 2 genuine Killa rk completely s hielded Audio Ave. N .• Nampa. Idaho. Tra ns form ers : I Baseboard; 20 feet T inned Bus-Bar; I .00025 F resh man Grid Condenser ; I Tubula r Gla ss Grid Leak: I Set Enl( raved B inding Pos t ~; 1 .002 Micon Conde nser; I .006 Mi.con Condenser: Exact Size Special Panel i I nstructions a nd Blue P rmt; "Enclosed lind m ao 1 made lor yOU in aPllrecia tion of your De LUl( C a ll packed in la r~e ha nd,ome pa rtItioned box. $34.49 com plete. Neutrodyne. This ma ll shows r esults I ohtained on Thursday eve!l\ng. ACCESSORIES TO PUT SET IN OPERATION March 27. 1924-a total of 35 statio ns from Ca nada to T exas and F londa . E ve rything nE eded t 'l opera te s et after huildin g- 5 T ested Tubes a nd from Massach usetts t o California . all in 5 hou rs- as far north a~ (Type 2OJA). $19.50: 2 45-volt extra large Va ria ble " 13" Batteries T oronto. a nd south to 1I1iami a nd Dallas. T o date I have lis teped t o a fo r Neu trodyne. $6.50; 1 60-ampere n our Storage Ba ttery (guar­ grand tot al of 57 s tations- 8 in New York ; 4 in .Newa rk; 3 in C.hlcago a n.d a nteed 2 year s). $11.25: I pair 3.000-ohm Phones. $3.75 ; Douhle Philadelphia: 2 in Pittsburg h. Davenport. H astlllgs. Kansas . Cltr . P rovI­ P lug. 90c: I A ntenna Equipment. $1. 50' C01\I PLETE OUTFIT. dence. Oma ha . Cincinnati and Los Angeles : a nd 1 each 1n Columhus. $43.40. (Accessories a! so sold separa tely. ) If you or~er . Build­ Toronto \ Vash in gt on. Z ion City. P la infield. Sche nect ady. R ochest er. ing Outfi t and Opera ting Out fit both t ogether we WIll m clude fi ne :Mahogany Fini sh D~b;~ ;:' ~1 ~~;~;O i s ~tn ¥1~~I; ~~w~ c \!I~i~. ~~'i(t o l~ ar~~ II~'ie v!fa~~: soAtlf~g: CABINET FREE Oakla nd a nd Mi a~l." H. Roberts. 2036 Woolworth Bldg .• New York City. SEND NO MONEY. We ship C. O. D. P a y your postman. The n ( These are from hundreda of lette .. con"an", coming in with hillh praioo.) build and enjoy your . et unde r our \ VR ITTEN ;\Oloney- Back Gua r­ antee sent with equipmen t . We acknowledge a ll o rders hy return mail. Ship same or following day. \\'e a nswer every letter we ~et on same da y. The R a dio Shack a re the largest R adio D ~a l e rs '" America. No in ferior goods. Only the best a nd most rellahle. You buy in safe ty. Send your C. O. D. orde r today. T his present low pr ice cannot cont inue. Act NOW. Cir cular FREE. ·,· it!1 Bro:H! ca~ t Li c;: t a nd -:\'C a p. RAG. 55 Vesey Street. THE RADIO SHACK Dept. New York, N Y. Always Mention RADIO AGE Wh en Writing to Advertisl!TS - RADIO AGE for June, 1924 The Magazi,,;e of the Hour 41 A Chat With the Big Fatnily

ADIO AGE has undergone a proc­ sent out. We would advise our subscrib­ will be necessary. The radiating effect ess of enlargement and extensive ers to be careful about permitting their may be partially reduced by connecting a R. changes have been made in all de­ mail to lie in hallways or on porches, as potentiometer in the aerial circuit. This partments. The magazine has moved into it has often come to our notice that maga­ is done by connecting the middle arm, or more roomy offices, the second move zines have been appropriated by people lever, of the potentiometer to the aerial which has been forced by increasing busi­ other than to whom they are directed, binding post on the set, and either one of ness within the year. after delivery by the mail carriers. the other terminals to the aerial. The radio public has been kind enough Another thing 'which saves time and This may sound peculiar, as it increases to put its stamp of approval on our peri­ gets your order out is to list all your the resistance of the aerial circuit, but, odical and as a result the task of making orders and subscriptions on a separate curiously enough, it does not seem to in­ good our slogan "Service to Readers sheet other than that of your pickups, rec­ terfere with the reception. First" has become more complicated and ords or questions. difficult. Correspondence is enormous and this chat with readers is for the purpose Technical Questions RADIO AGE and of suggesting ways and means of more Whenever your letter contains a request RADIO AGE ANNUAL effective cooperation between reader and for technical information, it is a good and A year's subscription to this magazin(' a nd a publisher. effective plan to list your questions on a copy of the famous handbook of drawings and We want to discuss details which, when separate sheet, which can be easily turned instructions on how to make s tandard receiving taken individually, are trifles, but which over to the service department for atten­ sets. 112 pages. become vastly important in the mainte tion without first waiting for your order nance of a smoothly functioning, exten to be listed, the subscription entered and All for $3.00 sive service system. RADIO AGE has a your instructions noted. . Send today by check, registered mail or m oney technical service department, the value of Subscribers are requested to enclose a order to which is known only to those who use it. stamped, addressed envelope if they de­ RADIO AGE, Inc. In order to make that department more sire an answer. No answers will be mailed 500 N. Dearborn St. Chicago, Ill. useful we are asking readers to keep in unless this detail is observed. mind the following details: Address your questions with regard to technical difficulties to RADIO AGE, Inc., Remittances Technical Office, 500 N orth Dearborn BREMER ~ TULLY Occasionally, one of our readers will Street, Chicago, Illinois, if you desire the $500 Nameless Circuit find it necessary to place an order for a promptest of service. back number; a copy of the Reinartz In closing this little get-to-together talk, B T 3 Circuit R. F. Trans formers and the $500 Nameless Circuit have solved the problem Book; or perhaps desires a copy of the we wish to advise the usual, old, and stere­ of Radio Frequency Amplification-Nothing new book just off the press, the RADIO otyped phrase, "Put the return address on to equal it for strength of signals. Orders are far in excess of production. Place your AGE ANNUAL. This involves the han­ all your correspondence." Write legibly, order with your dealer at onee for future dling of money, stamps or currency or and don't take chances in sending coins in delivery. Illustrated folder of Diagrams, etc., other form of exchange, as the case plain envelopes. on request. may be. BREMER .. TULLY In remitting by check, stamps or cur­ To Avoid Radiation rency, you run little or no risk in sending The fact that many receiving sets are Manufacturing Company the order by first class mail-but don't so constructed that they radiate an oscil­ 532 S. Canal St. Chicago Ill. you think that it would be more sure if lating wave from the aerial has been a you took the time to register your letter? source of constant interference which is In event that we fail to receive your letter, 378 DX STATIONS growing daily. As a result of an article DX Fans. If you have not logged 300 stations the matter could so much more easily be on 'this subject published a short time in past six months you need a Kennedy Three cleared up if the letter were properly Circuit Tuner. The Kennedy Tuner logged 378 ago, many letters have been received ask­ stations from September 15th to March 15th, in­ safeguarded. ing how this may be prevented, which cluding 2LO, London; 5WA, Cardiff, Wales; Copies of the RADIO AGE ANNUAL CFCN, Calgary, Alberta, Canada; KGW, Port­ shows conclusively that some of the fans, land, Oregon; KFI and KHJ, Los Angeles, Cali­ are sent to purchasers by parcel post. To at least, take this matter seriously and fornia; KPO, San Francisco, California; KGO and KLX, Oakland, California. assure our patrons of the promptest deliv­ want to do their part in the elimination ery, and to further insure their safe deliv­ Kennedy Tuner Takes the Place of of this nuisance. 3 H oneycomb Coils at $1.40 ...... $ 4.20 ery, they are listed at the Post Office. In 1 H oneycomh Coil Mounting...... 5.00 In the case of a regenerative set one I 23-Plate Vernier Condenser...... 5.00 event that any of our patrons fail to re­ can do much in the way of clearing up ceive their orders, we suggest that they INCLUDING GLOBE $5 00 $14.20 the air by learning to tune properly. Any TROTTER DIAGRAM • inform us promptly, in order that investi­ set in which the plate is connected to the T. J. KENNEDY gation may be made, and the trouble aerial will be one of the worst offenders. Radio Globe Trotter located without undue delay. In the operation of this kind of a set 470 W. 159th Street, New York, N. Y. GUARANTEE: If not satisfied after 30 days Subscribers some other method besides careful tuning will cheerfully return your money. Occasionally we are informed by our subscribers that they fail to receive their magazi~les , and we would like to advise that they notify the Subscription Service Department immediately, in order that the trouble may be located, and the cor­ No soldering outfit is complete without a good brush rection be made. Should subscribers change address or move, we earnestly re­ for applying the soldering acid. Every radio dealer quest that they inform us. Failure to do should carry these in stock. Put up, 1 gross to the so leaves a magazine without a recipient. package. Send for prices and samples. Incidentally, we wish to tell our read­ ers that we cannot assume the responsi­ bility for the loss of money in the mails or in transit, nor can we assume the loss The Specialty Mfg. Cotnpany of any orders shipped, when our records show that the order has been filled and 11400 Madison Ave., Cleveland, Ohio 42 RADIO AG~ for June, 1924 The .Magazine of Ihe Holtr

M. O. B., San Francisco, Cal. The gap between the electrodes was Don't fail to m a k e your about one-half inch, and during the storm, Qll estion: I have had quite an argu­ queries and letters conform ment with my landlord with respect to the heavy sparks jumped the gap, surprising danger of lightning striking an antenna, with the rules published in the everyone who saw the display. Another and I would like to have your opinion on May, 1924, Troubleshooter sec­ time, using an antenna during dry weather the subject. He says that it is very dan­ tion. There is no excuse for when a lot of static was in the air, I gerous, that it attracts bolts toward the not complying with rules such found that my antenna accumulated aerial wire, and consequently exposes one as were found necessary to as­ strong enough charges to jump the plates to the dangers of an electrical discharge sure all our readers an equal of a variable condenser which I had con­ of this nature. What is your opinion on chance of this service. nected in the antenna lead of the receiver. the subject? It is herein that the danger lies, and not . We have a number of ques­ if! the actual striking of the bolt. Answer: Funny as it may seem, some tions on hand at present that people persist in believing that radio an­ have not been answered be­ R. N., New York City cause their writers did not ob­ tennas "draw" lightning during an elec­ Question: Kindly give a diagram of the trical storm, and I want to say right now serve the rules as they were Low Loss Receiver described in your that this opinion is all wrong and should specified. Due to the g rea t March number in connection with a two­ be discouraged. In the first place, a bolt number of questions we re­ stage amplifier. I have constructed this has about as much chance of attacking ceive, this has been found nec­ set, and find it does everything you say it your antenna system, as it has of strik­ essary, in order that justice does. Tuning is very sharp, and stations ing your wife's clothes iine. may be done to all of them. come in with great intensity. The set is a Tell your friend that if your antenna very convincing argument for good con­ is properly protected by an approved If you don't know what we are referring to, read the notice densers, and has taught me a good lesson lightning arrester, w h i chis properly about choice of apparatus. grounded, the system becomes a protector published on page 42, Trouble­ of property instead of a hazard. How­ shooter section of the May, Answer : We are printing in Figure 1 a ever, a well constructed non-grounded an­ 1924, issue. diagram of the circuit you desire. Reports tenna has the properties of accumulating Technical Editor. on this receiver indicate that it is a very a strong charge of electricity during a popular one among broadcast listeners, storm of any great electrical violence, and Some time ago, I carried on a test to see due to the fact that it is easy to con­ if the antenna is not grounded properly. how much of this theory was true, and struct, easy to operate, and tunes very this charge can jump a good distance from leaving my experimental antenna, which sharply. C batteries should be inserted the lead-in end of the system into various happens to be very well insulated and un­ in the leads marked X if a high pi ate volt­ grounded objects. If the cbject happens grounded, I inserted a small air gap, one age is used. This will conserve your B to be inflammable, it can cause a fire , but side of which was connected to a good battery by keeping the drain on that part this is about the only danger which exists. ground. of the set as low as possible.

TICKLER C AVDIO ...... AMPI-/FIER

P ------.,6-

A B

Figure 1. A dia gram of the Low Loss receiver showing the addition of two stages of audio frequency amplification. C batteries cm: be added at the paillts l/I arkr- d X. RADIO AGE for June, 1924 The Magazine of the Hour 43 R. T. C., Chicago, 111. HOWARD PARTS Question: I have a single circuit re­ 3-lrt-l UNIT No. 1001 Rheostat, $1.10 No. 1003 PotentiolTleter, $1.50 ceiver, which I am told oscillates and No. 1002 MicrolTleter. $1.50 sends out carrier waves into the air which Audio A1l1PlifiEI' At All Dealer•. spoil my neighbors' reception. I am told that it does this only when the set is in the oscillating stage, and when it is doing so, I am not getting maximum ef(Iciency out of it. Is there any instrument that I could put in the circuit that would tell me when the set is transmitting energy? How can I stop it?

Answer: It is pretty hard for the aver­ 4248 N. Western Ave. age fan to tell when his set is in the oscil­ lating condition except by noting the noises which the set emits while tuning. When you tune across the wave of a broadcasting station, and the set gives This highly efficient unit consists of RHEO­ a whistle which varies as you move any STA T, SOC K E T and TRANSFORMER of the knobs, it is an infallible sign that adapted for any set where a mplification is desired. Will amplify your CRYSTAL SET the set is oscillating and transmitting fo·r loud speaker use. Audio energy. Due to its compactness it is ideal for use in Frequency Another test possible is to touch th~ making a portable set. Every 3-in-1 unit fully set in any part in the grid circuit or an­ tested a nd guaranteed. Specially wired unit for reflex w~rk. TRANSFORMER tenna circuit. If you have taps in the Bellt for Portable Set,. antenna circuit, you can try lifting the \VELTY'S Loud Speaker ...... $25.00 ~h~tw~~:b:!Z~~~i: a~~r;:~8~e~~I~~~a~~de i:'~;~= WELTY'S Loud Speaker Unit ...... 9.00 formaIlee. &atio 1 to 3,1 to 4. 1 to 5. $3.60.1 to 10. $4.60. ~witch lever. If the set is oscillating, a Ask your dealer for this "Little Wonder" pronounced "thud" or "thuop" will be STRICTLY HIGH GRADE. heard in the phones. If not, a light click Mail orders proTTtptly filled. pr~mi~r £l~dri~ ~OmJ1iln!:f or scratch will be heard. 3803 Ravenswood Avenue CHICAGO \VILLIAM A. \VElTY E.c CO. Another sign of an oscillating receiver 36 So. StatE 51. is a slight whistle or whine with the signal Dealers Correspondence Invited. 1IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIilllllllllllllllllil11 11 11111111 when reception is carried on. You can put a milliameter of about a to 25 milliamps $1 00 STARITE $1 00 maximum in the plate or tickler circuit and watch the meter pointer as it travels THEREST CRYSTAL IN THE WORLD. across the face of the scale. As the set Unconditionally Guaranteed. bursts into oscillation, the meter usually gives a decided swing toward maximum, PRICE, $1.00 and worth it. indicating resonance. This is nearly always He a rranges in orderly fashion the mass and jumble of Broadeasting Stations that are a sign that the set is oscillating. seeking entrance to your set and brings 't;!m STAR CRYSTAL CO. in, one at a time. so you can enjoy them! N ever re .. The best results are obtained when one duces, but nearly always increases volume. Add a 53 W. Jackson Blvd., Chicago, m. Ferbend Wave Trap to your set and '4Police" your tunes just below the regenerating point, reception. Regulate the Traffic! Factory, Detroit, Mich. Guaranteed to tune out nny I nterferlnR' station. The price as the signal will then come in without f s $8.60. Shipmentfs made parcel post C. O. D. plus a f ew 1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111 cents pos tage . If you prefer, send cash In full with order the customary squeals and whistles. To and W~ will ship p ostage prepaid. Send accomplish this, reduce the fi lament cur­ U8 your order today. rent, and the tickler coupling, and if it is FERBE1S'D it:g.::J'c CLASSIFIED ADVERTISEMENTS ()~~ fZU~··:: COMPANY slill difncult to control, adjust your grid WOlVe 16 E. Soutb leak until it does so. It is often neces­ Water St. sary to use a smaller grid condenser to Chlcago,lll. accomplish this purpose. RADIO CIRCUITS However, u n d e r no circumstances should you let your set radiate strongly, If your Neutrodyne won't "Neut" o. k .• send lO e RADIO CABINETS fol' Details of Kladag Coast to Coast circuit. bill of as the use of aperiodic coupling will re­ materials. etc .• to change over your Neut into a set RADIO SETS that will bring them all in from Mexico City to duce this nuisance to a minimum. TtUlucu. Cuba. on a loud speaker. Or send $5.00 for EQUIPPED PANELS all extra parts. blue print, etc., you need to do this. Stamps accepted. Radio list for stamp. SUper Het ~ro­ dyne specifications, 10c. Kladag Radio LaboratorIes, A. M. B., Des Moines, Iowa Ask Us About PHUSIFORMERS Kent, Ohio. Question: I have read with consider­ LAKESIDE SUPPLY CO., Dept. R RADIO EQUIPMENT. able interest the comment on honeycomb 73 West Van BUlen Street Harkness circuit two tubes take place of four or Telephone. Harrison 3840 CHICAGO, ILL. five' Detector 2 R. F., 2 A. F. Complete, genuine receivers, and would like very much to part's including set of Flex-o-formers, Rbeinhold de­ tector a nd 201·A type tubes, $23.50. Range, 1,000 to have you print a diagram of a receiver 1 500 miles on loud speaker. New Catalog 64 on re­ using this circuit. I note in your maga­ q;"est. Royal Manufacturing Co .. 206 Broadway, Dept. 19. J:l/ew York. zine of a month or so ago that you men­ tion the results obtained by T. J. Kennedy, TRANSMITTING SET NEXT TIME INSIST and would like very much to have a dia­ 15·20% DISCOUNT ON ALL STANDARD RECEIV. ON ERS. Fried·Eisemann Neutrodyne . $125.00: New Radi­ gram of a receiver of the type used by olas, etc. Thomas Radio Co .. 111 Dex St .. Muncfe, Ind. him. RADIO BATTERIES Answer: I am printing in Figure 2 a "COMET" Super Radio A and B Circuit Batteries, which brfng in long distance reception. Sold for cash or on payment copy of the diagram used by Mr. Ken­ "B" BATTERIES plan. Write for prices and details. Radi,! Bat~ery Corporation, 501·B Industrial Bank Bldg., Fllltt, Mich. nedy in his record-breaking receptions. The antenna series condenser (which by At all good radio MISCELLANEOUS stores or write the way can be placed in either antenna 158 GENUINE Foreign Stamps. Mexico War Issue •. Venezuela Salvador and India Service. Guatemala, or ground leads) should be a good 23-plate ELECTRICAL MFG. AGENCY China, etc., only 5c. Finest approval sheets 50 to 60% . Agents Wanted. BIll' 72-p. Usts Free. We Buy vernier type and is not very critical in Stamps. Established 20 Years. Hussman Stamp Co., tuning. The other secondary condenser Dept. 152. St. Louis, Mo. across the honeycomb is the tuning unit 44 RADIO AGE for June, 1924 The :Magazine of the Hour and should be of the very hjghest grade for maximum results. The detector rheostat should be of the vernier type to permit close adjustment of U lUll \ ~ the filament current; a factor of great i UUUUIIUIIU importance in any receiver. Mr. Kennedy uses fixed condensers of .00025 MF ca­ pacity with a grid leak shunted across the ...... - G and F posts of the audio transformers (!.,.-l {L-.I-- , t to help eliminate noises in the set, an idea which is very practical. No jacks are \-Q ev- used in the detector or first stage circuits, '<:~~ tti due to the fact that they coritribute to noises in the receiver. ltl~~2nJ mWY~H~ M. T. P., Birmingham, Ala. Q Question: I have a three circuit re­ r~ .!!!!. ceiver, and would appreciate a few instruc­ ~- tions as to the method of tuning a receiver of this kind. I find that it tunes very ~ ~.~~In , ~( ;.iii- closely, but I have much trouble in decid­ Sl S: ing which control I should manipulate to ~ ~ I J\ HH\Ah get the best results. Could you give me II a few pointers? Answer: The matter of tuning any receiver, as I have said before, is a matter f"J ~f...... -'~ ~. ..1 of practice, and the familiarization of "h ---... (~) ~- .~ one's ears to the various noises of the set. ~ ~ l~/ However, I will outline briefly the pro­ ~ ~ C-r- - Wff cedure that i~ usually followed with a ~ ' JIJ ~ standard three circuit tuner using two ~ ~~ variometers and a coupler. Set the grid Yll ~ and plate variometers at zero. Vary the ~ tQQQQQQ~~ - secondary (rotor) of the variocoupler --"iii" until a signal is heard. This signal should -~ be tuned in to maximum intensity. / §[OM!!6: Next, vary the grid variometer until the signal is further increased in strength.

~ ~ The plate variometer is then varied until S ~ 1,~ a point is reached where the familiar c: "thud" or "thump" accompanying regen­ ~ ~ I'll I eration is heard. The filament can then

<{~ '" be turned back until the signal comes in ~ IOIHh ~ clearest, or the plate variometer can be brought back (or both) until a point just ~ ~ ~@ (~ below oscillation is reached, where the ,.\ signal will be loudest. It is customary ~ 11'7- ~ to set the secondary of the coupler first, ~ ~I ij I---. and then vary the grid and plate variom­ ...S eters together until the best effect is ~ 'J I"" AH reached. If difficulty is had in finding ~ this point, the rheostat is resorted to, and ~ ~} ~ ~ the filament should be decreased or in­ ~ creased until the proper value is found. ® I am assuming, of course, that the grid ~ I~ "> leak and other values such as the plate \ -, ~j battery are at maximum effectiveness. If ""11 interference is encountered, the secondary Iq?Qqo~QnJ of the coupler should be turned to de­ crease the coupling between that coil and ~ ~ ~ ,OambOl! ~ <;\ the primary. r;; I~ H~ H~ A. S. M., Toronto, Ont., Canada iQ 'lI to ~ \, ~ Question: I have constructed one of § - ~ ~ fmltM your super-heterodyne receivers as was de­ ~~~ scribed by your Mr. McCullah in the ~ ~ ~ April, 1924, issue. While the set func­ k ~~ ~ 11'5 tions, I find that its range is rather lim­ ~ ~ /[1 Ir-- ited, and I would like very much to know (~ if you could suggest anylhing to improve \ ~ lhe range. I Q : IIII~ I §J; I Answer : In Figure 3, I am printing a ,fJ diagram of the super-heterodyne receiver '"I of the type designed by Mr. McCullah I 1nnnn onO nnnM I with several changes thereon. u.. [~' I The fixed condenser across the primary I>i-=~------,&W1r---""""'-----t~III' of the LWC (long wave coils) is sub- RADIO AGEjor June, 1924 The Magazine oj the Hour 45

L85

_N -6r. -p ~------~------~~L------~------E--~------~~----~

Figure 2. A diagram of the receiver used by T. 1. Kennedy in his record breaking receptions. The secondaries of the audio transformers are shunted by a .00025 MF condenser and a variable pencil mark grid leak. stituted with a .0005 MF variable, which Wallace and Governor Gifford Pinchotof permits the use of different intermediate Pennsylvania were broadcast from thirty waves for amplification. With some minor radio stations during Forest Protection changes in the plate circuit of the. first Week, April 21- 2 7, as a means to spread detector and grid circuit of the oscillator, the doctrine of forest fire prevention. Sev­ the circuit is practically the same. For eral of the messages were broadcast per­ lack of space only 9 tubes are shown, the sonally by Governor Pinchot and Secre­ original circuit using 10. The omitted tary \Vallace from stations in Harrisburg, Quality Not Sacrificed tube is the radio frequency amplifier which Pa., and Washington, D. C. In addition is added in the ordinary manner. to their messages, talks 00 forest fires were made over radio by forestry officials of many states and by members of the Scotch Loop Gets WGY Forest Service. Early reports indicate James Mackintosh of Inverness, Scot­ that the radio appeal for forest protection land, found WGY signals coming in so was so effective it will probably be made a strong that he decided to try a frame regular government policy. . aerial consisting of four turns of bell wire wound on a square frame with four feet sides. "Surprising were the results," CRYSTALS reports Mr. Mackintosh, "the music from A-I GET DISTANCE WGY was distinctly audible and the Ideal for Reflex speech just defined enough to enable the "Have received 30 stations on my Crystal Set using A-I Crystals. including KGO, Oakland, call sign to be obtained." California, 1,525 miles distant." be shipped the day w e receive your order Gilbert Beck. Texas. Express C. O. D .. subject to your examination on arrival. Our A-I CRYSTALS guaran t e e accompanies American Sets Wanted each battery. W e allow 6% Guaranteed Tested discount for cash in full It is only natural that for American with order. ¥ou cannot Sent Postpaid 50c Each lose! Actquick. Send your broadcast reception American-made appa­ Sixty Cents if sent C. O. D. order today-NOW. ratus is sought abroad. and nearly every California Radio Minerals week requests for radio apparatus, data Arrow Battery Co. HARRY GRANT, JR. 1421 South Wabash Ave. and catalogues are received by the De­ 904 Oak Grove Ave. partment of Commerce. Many overseas BURLINGAME CALIFORNIA Dept. 11 Chicago, III. seek to become agents of American manu­ facturing firms and the Department is forced to keep a list of such requests for reference. Just now Italy is seeking re­ ceiving sets suitable for reception on wave lengths trom 400 to 600 and 400 to 4,000 meters, and ranges from 10 to 2,000 miles. Become a big·pay man in tb e greatest industry of time. Q!1~cklY, easily Calls have also been received recently and right at home, you can fit ),ourself for highest salary pO~l1tlOns, or you can cash in on your spare time. The call is urgent for mechaDlcs operators, from Brazil, Portugal, Sweden, New Zeal­ designers, inspectors. Unlimited, fascinating opportunities on lland or sea_ and and Australia for apparatus and bat­ teries. Some countries are already jealous I ;'~~N YOU AT HOME ~~ A RADIO EXPERT Under my practicald~asy to understand, instruction-you qualify in an amaz­ of American sets and have prohibited its ingly short time. !'IO previous experience is necessary. Every branch of importation or imposed high tariffs to pro­ radio becomes an open book to you. You learn how to design, construct, operateirepair, maintain and sell all forms of Radio apparatus. My methods tect home-made sets. are the atest and most modem in existence. Wonderful homeconstruotion tube W,-te Today "RadIo FREE FREE receIving set of tho latest dealsn. I Facts" Radio to Prevent Forest Fires A. G. Radio RADIO ASSOCIATION OF AM ERICA,4513 Ravenswood Ave .. Depl.26.CHICAGO Messages by Secretary of Agriculture 46 RADIO AGEjor June, 1924 The Magazine of the Hour -WITH

New Loud Speaker Electrad Variohm On Market The Inside of a Radio Factory Radio listeners who now demand not Considerable popularity for Electrad's By E. J. Craine only volume and quality of tone, but new "Variohm" has been reported by deal­ The inside of a radio factory is like pleasing appearance, will find in the new ers throughout the country. It is said to nothing else in the world but a gigantic Western Electric No. 14-A Loud Speak­ be the newest thing in variable grid leaks, bee-hive, and one of its chief points of ing Telephone Outfit an efficient cabinet being unusually compact and taking up similarity is the promptness with which type of instrument that makes use of the little room on either panel or inside the drones must be eliminated. latest developments in the electrical com­ set. The same curiosity that makes a small munication art. It is a combined loud boy want to see the inside of a watch speaking telephone and audio-frequency A complete range of resistances in one urges the average " fan " to see the inside amplifier. This outfit, including the horn, unit is afforded, ranging from one-fourth of a radio factory. The results, however, is built into a mahogany cabinet of at­ to ten megohms. The Variohm is non­ are not so disastrous in a radio plant, tractive design, which may be placed on microphonic, moisture proof, saves B although a feeling of awe casts its spell a table. batteries and does away with circuit throughout. The novel feature of this outfit is the noises, according to a circular sent to horn, which, folded into a relatively small dealers by Electrad, Inc., of New .York Visits Freed-Eisemann compass, has yet the properties of a City. Another advantage is the elimina­ It was to Joseph D. R. Freed that I straight horn almost twice as long as the tion of local stations and the opportunity confided my longing to visit the Freed­ cabinet is deep. Despite its small size, it to receive distant stations without inter­ Eisemann organization in Brooklyn. is more effective even than the horn sup­ ference. The first room I entered was filled with plied with the 10-A and 10-D loud speak­ a huge pile of panels, several feet deep and ing telephone outfits. Connected to the still enclosed in their white wrappings. horn is a loud .speaking telephone similar On Freed-Eisemann Force Nearby, workmen were drilling four pan­ to that used on many occasions to project els simultaneously and with the greatest the voices of speakers, notably at the in­ care, with machines that are set with auguration of the late President Harding. Amateurs all mathematical accuracy. Two stages of audio-frequency ampli­ o v e r the United Once drilled, the edges of the panels are fica tion are provided, the last stage using States know Ed­ smoothed, and then, with a ba(tery of ten two tubes connected in "push-pull." This gar K.. James, who huge machines that look like overgrown arrangement gives the maximum output conducted the first drawing toys, the name, "Freed-Eise­ with practically no distortion of the qual­ r a d i 0 show for mann""is engraved, as well as the various ity of the transmission. Volume control amateurs, and as­ names which indicate dial numbers, etc. is effected by turning a knob on the front sisted in the latest Rows and rows of benches where expert of the cabinet; this varies the audio volt­ show held in the ,vorkmen were winding coils were found age applied to the grid of the first tube. Pennsylvania Ho­ in an adjoining room. Other workmen A snap-switch, also controlled from the tel, New York. He varnish the coils with a secret prepara­ front, turns on and off the filament cur­ has always bee n tion, after which they were left to dry. rent. active in amateur Coils and condensers are then attached to The outfit has been designed to operate r a d i 0 and is a the panel, which soon begins to be recog­ with No. 216-A tubes, which are designed m e m b e r of the nizable, with its three coils, four posts, to work on a 6-volt storage battery. Plate Sec 0 n d District and tube shelf. current supply may be secured from any Executive Radio Soldered parts are given the closest battery which will give 22 milliamperes EDGAR K. JAMES Co un c i l. During scrutiny and wiring is tested by experts. at 120 to 135 volts. Six large size 22 0 - the war he was in­ Every speck of dust is blown ou't with a yolt "B" batteries may be used, or a \Vest­ structor at ·McCook's field in Dayton, strong compressed air blower. Not the ern Electric No. 2-A Current Supp'ly Set Ohio, and In 1919 he started the radio de­ smallest detail is left to chance, and each will furnish both filament and ,plate cur­ partment for Stanley & Paterson, iadio step in the work of construction is tested. rent. jobbers. He was with the De Forest If any part falls under perfection, it is Since this outfit can do no more than Company two years, and two years with sent back and often broken up. give an amplified reproduction of the out­ the A. H. Grebe Company in Richmond When a set is still in embryo state it is put of a radio receiver. it is important Hill, L. 1. Now the Freed-Eisemann given a long tag and in the course of com­ that the latter be capable of giving an Radio Corporation have him, and he is pletion each man who contributes to its output of good quality and of sufficient out doing a big job in the Eastern terri­ construction signs his name to the tag; so, volume to be satisfactory to a listener tory. when the set finally stands forth, every using a telephone head set. It should be worker's signature is there. These tags remembered that this outfit is in no sense are filed in order that inferior workman­ a radio receiver or tuning device. Four Brazilian Stations ship can be traced. Permission to establish four r a d i 0 British Interest Grows broadcasting stations has been granted by Tested for Flaws Enthusiasm for radio telephony con­ the Ministry of Public Works of Brazil to In the engineer's department the re­ tinues to grow throughout Great Britain, the Brazilian Radio Telegraph Company ceiver is neutralized and tested again for according to Acting Commercial Attache for the purpose of broadcasting informa­ any possible flaw. When the apparatus is Hugh A. Butler. Up to March 1, 1924, tion, lectures, concerts, etc. The four sta­ finally enclosed in its cabinet it is sent to over 600,000 licenses for receiving sets tions are to be located at Sao Paulo, Bello a "laboratory" where it must run the had been issued. Horizonte, Bahia, and Pernambuco. gauntlet of examination and test. After RADIO AGE for June, 1924 The Afagazine of the HOltr 47 vas sing tnrough the hands of many skilled Chicago Radio Makers Unite workmen it is enclosed in a carton. Now you can Air chambers protect the set perfectly The Associated Radio Manufacturers, in the carton, keeping it absolutely safe an organization of manufacturers who will until it arrives at its destination. produce $150,000,000 worth of radio sets UNDERSTAND The Freed-Eisemann plant occupies during 1924, has been organized in Chi­ about 25,000 square feet. More than 400 cago as a means of maintaining radio RADIO! workmen are employed in the factory. trade relations and increasing the effi­ ciency of radio products. Take the mystery out of it­ Many of the big radio manufacturers build and repair sets-explain Phonograph Dealers Interested in the Chicago district are represented in the vacuum tube-operate a t~e new organization. They place their transmitter-be a r!l.dio expert! Phonograph de a 1 er s recently have 1924 production estimate at a minimum shown considerable interest in radio. The of $150,000,000. More than 2,000,000 increased publicity being devoted to radio transformers alone are expected to be 1 VOLUME is expected to result in more sales for turned out. In the manufacture of radio 514 PAGES phonograph concerns as well as all classes sets the Zenith Radio Corporation has of stores who sell radio. fixed its minimum at $3,500.000 worth of Compil.d b, To "tie in" with this activity, the Man­ sets. HARRY F. DART hattan Electrical Supply Company is With the industry traveling along at E.E. offering for sale a new phonograph attach­ such a lively clip, the manufacturers de­ Formerly with the ment under their trade mark, "Red Seal." cided to get together and enlist their co­ Weatem Eleckie It consists of a special Red Seal receiver operation in a drive to eliminate the evils Co., and U. S. attached to a heavy non-resonant metal of radio reception as well as the evils Army lastrudor base with air chamber and diaphragm offered by those who attempt to foist in­ of Radio. especially designed to operate the large ferior apparatus on the radio public. air column of a reproducing horn. Herbert H. Frost, A. J. Carter, Frank Attachment is made to the tone arm of Reichman, A. A. Howard and E. N. Rau­ Technically Edited by F. H. Doane the phonograph by means of a soft rub­ land were elected as a temporary board 40,000 ALREADY SOLD ber tube. This new attachment is very of directors. sensible to faint signals and re-creates This practical and authoritative Handbook is At the first general organization meet­ considered the biggest dollar's worth in radia musical programs faithfully. ing the following firms were enrolled: to-day. Over 40,000 homes rely on the I. C. S. R a u 1 and Manufacturing Company, Radio Handbook to take the mystery out of radio. Howard Radio Company, Carter Radio Why experiment in the dark when you can New Managers for Goldschmidt Company, Herbert H. Frost, Inc, Belden Quickly learn the things that insure success ~ Hundrec1s of illustrations and diagrams explain Manufacturing Company, Premier Elec­ everything so you can get the most out of what­ John B. Price and Harry Kamen have tric Company, Bremer-Tully Manufac­ been appointed to district managerships ever receiver you build or buy. turing Company. Dudlo Manufacturing I t contains: Electrical terms and cir­ by the Goldschmidt Corporation. Mr. Company, Trimm Radio Manufacturing Price has been chosen New York district cuits, antennas, batteries, generators Company, Runzel-Lenz Electrical Manu­ and motors, electron (vacuum) tubes, manager and will have charge of the facturing Company, Multiple Electric many receiving hook-ups, radio and audio supervision of sales of N & K Imported Products Company, American Art Mache frequency amplification, broadcast and Phones, loud speakers and other products Company, Seaman Paper Company, Elec­ commercial transmHters and receivers, which the Goldschmidt Corporation plans wave meters, super-regeneration, codes, trical Research Laboratories, Walbert license rules. Many other features. to put on the market soon in Northern Manufacturing Company, Winkler-Reich­ New Jersey, greater New York, New York man Company, B Ii e 11 Manufacturing A practical boolc. Written and edited by ex­ State and Long Island, perienced engineers, in plain language. Some­ Company.. F r en c h Battery Company, thing useful on every one of its 514 pages. The Mr. Kamen will have charge of the Zenith Radio Corporation. authority that covers every phase of radio, all New England district and will handle th~ under one cover in one book fot' one dollar. Don't same products as Mr. Price. Mr. Kamen spend another cent for parts, turn a dial 01' touch a tool until you have mailed $1 for this I. C. S. has been connected for twelve years with G. A. Sawin Elected the A. C. Gilbert Company of New Radio Handbook. Haven, Conn., in the electrical speci!'l.lty G. A. Sawin, assistant to manager, Sup­ Send $1 at once and gel Ihis S14'pag" business. ply Sal e s Department, Westinghouse I.C.S. Radio Handbook-Ihe biggest valDe in Electric and Manufacturing Company, rdio lo-day. Money back if nol salislied. has been elected chairman of a new sec­ Cruver Has New Condenser 1_ ----- TEAR OUT HERE ---- ..., tion of the Electric Power Club. The sec­ I INTERNATIONAL CORRESPONDENCE SCHOOLS I The Cruver Manufacturing Company, tion, including instruments and instrument Box 8785, Scranton, Penna. I Chicago, has just put out a new condenser, transformers, was recently organized. I I enclose One Dollar. Please send me-post- invented and designed by G. M. Proud­ Mr. Sawin, who is chairman of the In­ I f~\~~~~~rs ~o~~-rw ;/i CdmS'no~:~tfr e l~aS~I~?SO~~~ I I ~illa~er~~~~l' ::,;h~on~~~k within ave days anll you I foot, their engineer. !The condenser cuts struments and Measurements Committee down the inefficient capacities by means of the American Institute of Electrical I I of mounting the stator plates on two rods Engineers, has also been appointed chair· I :-lame ....., ...... I instead of three, thereby reducing losses man of the Institute's section for revisin g ! I to a negligible quantity. the Institute's stanclardization rules per­ L- ~~e~:..:.:. .. .::..: .~.::;,:~ .. ~.. :.:.:..:::.:.:::::::..:.:. .. =~ .J The 23-plate condenser showed the taining to instrument transformers. to hear programs from stations same rliading at maximum capacity and His wide experience with instruments YOU 400 to 1,000 Miles Away. [ 290 meters as the standard used, which is can show you how to get them and transformers will be of great aid to DON'T NEED on YOUR CRYSTAL SET. said to have a loss of only seven one­ Mr. Sawin in the new duties assigned him. Changes often cost Less Than thousandths of one per cent at a capacity One Dollar. Send self-ad­ dressed envelope for picturc of .001 M. F. The moclel was used in the TUBES of my set. Trans-Atlantic test in the "low loss" tuner Jacquet With National Carbon LEON LAMBERT designed and operatecl by F. J. Marco of 540 So. Volutsia. Wichita, Kansas Experimental Station OXBA, Chicago. Lloyd Jacquet. formerly with the West­ When the group plates are set for the inghouse Electric, has recently been coarse adjustment, the reading shows on placed in charge of the publicity section AUTHENTIC-ACCURA TE the large scale. The knob is then turned of the National Carbon Company's radio RADIO AGE in the opposite direction and the fine ad­ division. Previous to his connection with MONTHLY DATA SHEETS justment is read on the inner scale, thus Westinghouse. Mr. Jacquet was radio ed­ Pages 37 :md 39, This Issue enabling an accurate log to be obtained. itor of the New York Evening Mail. Always Mention RAD IO AGE Wizen Writing to Advertiser; 48 RADIO AGE for June, 1924 The Magazine of the llour Evils of Hotne Broadcasting By L. O. MARSTELLER

H E trouble caused by an amateur's ously. Now let us consider the proper of the secondary circuit. With this type innocently operating his receiving operation of this set. - of receiver, it is almost impossible to tune T. . set as .a miniature broadcasting sta­ With the tickler set near zero, bring the ~n a station without radiating an interfer· t IOn IS a radIO bug-bear that can easily be tuner control to approximately the setting lllg wave. Every time that the third con­ overcome with a little thought and study where you would expect to find the de­ trol is tuned to the secondary circuit, an on the subject of radio interference. sired signal, and, with the other hand interfering wave will be radiated. Nearly all the sensitive receiving sets bring the tickler control up to the point Can Be Heard Six Blocks in use are capable of broadcasting speech where a sl ight hiss or rustle is heard and and music. This can readily be done by keep the tickler so adjusted as you more How far will anyone or all of these the use of a microphone properly con­ accurately tune in the signal. three types of receivers transmit? Any­ nected to a receiving set. If a slight change of the tuner adjust­ one will cause interference over a distance A microphone is a simple little device, ment causes a squeal or whistle to be of four city blocks and can under most one form of which we use every day ; heard, you should immediately remedy favorable conditions be heard 'six blocks namely, the part of the telephone into matters by dec reasing the tickler until the away. which we talk. Talking into a very sensi­ whistle disappears. If you do not de­ Possibly the evil has bee n rec ognized in the cities where so many receiving sets tive microphone causes the voice to affect crease the tickler setting, your set will the powerfu l radio waves sent out by the must be used within a small area, and, that continue to act as a transmitter and radi­ greater co-operation between neighbors t ransmitter, which is fundamentally a ate an interfering wave. This will cause has necessarily been obtained. large sensitive receiving set having a your neighbors to receive a whistle like microphone connected to it. The tickler noise mixed in with the concert music on the transmitter is necessarily adjusted from the broadcasting station. Many Sophs' Radio Party Spoiled so as to make the circuit oscillate and times music of excellent quality is con­ consequently transmit radio waves just as demned because of the interference caused Troy, N. Y.-When the Class of 1926 your receiving set will do with a similar by the wave sent out from a neighbor's of the Rensselaer Polytechnic Institute tickler adjustment. receiving set. staged its big social event, the Sophomore If I thought that you would use the With a very little practice the single Soiree, the students wanted the whole microphone only to reprimand your neigh­ circuit receiving set can be operated night world to know they were having a good hor, who is causing his receiving set to after night without causing any interfer­ time. t ransmit whistles and squeals, then I cer­ ence. And the world would have known it if tainly would explain how to connect the the envious freshmen hadn't known some- oevice to your set. However, there is The Three Control Type thing about radio. always the poss ibility of the ladies broad­ Another type of receiver which often The sophomores had .persuaded Station casting tea party gossip or the uncanny finds a place in the amateur's home and WHAZ to hook up with the 105th Regi­ East or West wind from aMah Jong sometimes is used for broadcast reception, ment Armory, where the event was being party, so I shall leave the home broad­ has one more control than the single cir- held, and put the syncopated music of casting idea for you to think about. cuit se t, making a total of three controls. Ben Selvin and his Moulin Rouge Orches- The purpose of mentioning the possi­ tra on the air. O ne control tunes the primary or an- bility of using the receiving set as a broad­ tenna circuit and the other tunes tne sec- Wires, microphone pickups and electri­ casting station is to call your attention ondary or tube circuit. The third control fiers were placed in their proper places, to the power you control with the knobs is marked tickler or intensifi er. This re- and on tests held early in the evening a nd dials on yo ur set. ce iver is very selective, but requires con- everything worked perfectly. After lo~al If you do not have a microphone con­ siderable skill and patience in order to broadcasting stations closed for the night nected to your receiving set, you can still tune in weak signals. As this type of the announcement was sent out that transmit, but it will be whistles and receiver has three controls, it is rather WHAZ would broadcast the student affair. squeals which are a source of interference difficult to keep the tickler properly ad- Radio listeners settled back to hear the t o your neighbors. justed as the primary and secondary con- jazz music and gay laughter. troIs are operated. The general tendency But something went wrong. There came Whence That Squeal? is to set the tickler to maximum and then occasional strains of music, interrupted by tune the primary and secondary until the long periods of silence. The radio men Many times during the reception of an whistle like note of a broadcasting station were stumped; they inspected the ap­ interes ting program, one will hear a is heard. paratus, changed the microphone and whistle or squeal causeo by a neighbor who improperly manipulates the controls For people who only have two hands, tested the wires-but still no music came of his set. The fact that 'he can very there is only one way to operate such a forth. although the orchestra was playing easily prevent such interference is an ex­ set and not cause interference: that is. to for all it was worth. cellent reason for paying him a visit and calibrate the secondary circuit by marking It was the first time i);.l two years that explaining the situation. Before paying the proper setting down on a chart. Then the station's program had been spoiled. your neighbor this instructive visit, how­ to tune in a station it is only necessary After several hours' investigation the "ex­ (' ver, it would be well to learn the cause, to set the secondary control to the proper perts" discovered that in an obscure place eff ect and remedy for such interference. point as determined from the calibration ' back of the Sage dining hall the trans­ chart and adjust the tickler to the point mission wires had been tapped in two There are several types of receiving sets where a slight hiss or rustle is heard as places with leads to the ground. whi ch can be made to act as a transmitter. The first of these is the favorite set, a t~ e primary circuit is tuned to the desired After a little sleuthing, the investigators single circuit receiver. There are two signal. ' forced a group of freshmen to confess controls on a single circuit receiver. One There is one other receiver which is they had tapped the wires and inserted a of these controls is known as a tuner commonly used. This receiver causes a microphone intended to broadcast remarks handle or knob. This control makes it great amount of interference, as it has harmful to their hated rivals-the sopho­ possible to tune in one station and elimi­ three tuned circuits. Two of the controls mores. Fortunately the second micro­ nate another. The other control is a are marked primary and secondary and phone did not work, but the frosh took tickler or intensifier. Its purpose is to are manipulated to tune in a signal. The solace in the fact the sophomores' pro­ increase the signal strength. Both tuner third control acts · as a tickler and has a gram was not broadcast to a wondering and tickler should be operated simultane- definite adjustment for each adjustment world. RADIO AGE for June, 1924 The Magazine of the Hour 49

.. ... ' .~ . r ..~ ..""""""' .. . ,.- .. ~~..~ .= ...'~ .r .~.. n ~ . ..~ ~ . .r. ~... ~~':::::: " :J5.r!@" ~~~~~~~~~~~,,~ Radio Age and ((QST"- $4.50 in Subscription Value for Only $3.00

Two yearly subscriptions The two magazines, together, cover for slightly more than the the radio field. regular cost of one. An extraordinary offer for a ".QST" is the official . organ of the limited period. Quick decision will save you American Radio Re ay League. It is from $1. 90 to $2.40. devoted entirely to amateur radio and Radio Age, purchased is a standard publication on technical each month on the news­ facts connected with radio. stand, would cost you $3.00. "QST" would cost Radio Age is in the front rank as a you $2.40. The regular magazine for the set maker and the subscription rate for Radio Age is $2.50. For broadcast listener. It is the hand-book "QST" it is $2.00. of thousands of experimenters in home workshops. Best isometric drawings of standard circuits; clearly written, complete de­ scriptions of construction details; com­ plete corrected list of broadcasting sta­ tions revised each month; news of latest developments in radio; calls heard by amateurs; new designs and equipment; scientific data. All this Mail The Coupon Today! for $3.00 a year.

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Always Mention RADIO AGE When Writing 10 AdvertIsers 50 RADIO AGE for June, 1924 The Magazine of the Hour Corrected List of U. S., Cuban and Canadian Broadcasting Stations Complete Each Issue

H E list of broadcasting stations on these pages is brought up to date each month by additions of new stations and deletion of those which have suspended ope ration. The list is the product of a T vast volume of correspondence a nd its completeness is due in large measure to the assista nce of our special news ser vice in \Vashington, D. C. Suggestions, corrections and additional data will be welcomed from reade rs and broadcasters.

KDK A \Vestinghou se E lectric & Mfg. Co ...... •...... E ast Pittsburgh 326 KFLH 261 K DPM KFLP ~ ~~r~~f; ~ ~ ~~sfe~ · .· .·...... •...... ·.·.·.·.·.~~~}raa; ~~~ : }:\~~ 240 K D P T ~~~~~ ~~o~~:c~ l ~~~ rito~. ~~~ ' . :.~':::::: :: : '. '. '.:'.'. ·. Sa~ l eD1~~~~· co,.7f~ m KFLQ Bizzell R a dio Shop ...... 00 •••••••• • Little Rock. Ark. 261 KDYL KFLR Unive r sity of New M e.led to a t wo-stage a mpli­ tisers are signing up for time fier with advantage. contracts. They know. INTRODUCTORY OFFER Upon receipt of $13.85, we will ship you the Every buyer of Radio Age complete set including: T he nabydyne .. tceiver. Ope g ua ra nteed tube. a ny is a radio fan. The magazine type. One pair of h e~d ph ones. I'or table style B '·attery. 22% volts. One A battery. dry cell. Aerial offers a highly specialized cir­ a nd ground connection. culation. Advertisers reach ex­ Money-back guarantee on any of the a bove a rticles . $50.00 IN CASH \ Ve can supply you w ith s t a ndard type t ubes a t $3.00 actly the circulation they are will be givc n ror thc best acc<,pt.a ble plan o r a each. Write forourdescriptive circula r on ra dio tubes. case t o cncl()se I.he Bab ydync wIth tubes. paying to reach. batterIes a nd headphones. THE "MUST" IN THE CASE: It must be Ug ht. It must be compact. It must be portable style . It must be of fair strength. I~TERNATIONAt Can we send you It must be chea p to cons truct. It must be ingenious in build. SOM EONE or thc Babydyne lliIers wl11 wIn I.Ws prlzo; It m ay be you Ir you send us your a rate card? d iagram and puotograph. BABYQYI MAKE THIS SUMMER DIFFERENT FROM LAST .;; \t mmer hy taking advantage 01 our sr)(!cia l offer. You can never forget the thrills that come in using a Babydyne o n your v.:lcatioll o r o n a motor trip. 1?ADIO RECEIVER RADIO AGE, Inc. (Upon reques t. we will give you free info rma tio n on how to e njoy a concert while a uto riding. ) No TR.ADE. MARK matte r in what part o f the country you may be. we gua ra n tee that the Ih bydylte \I'ill tune in some sta­ Manufactured b y 506 NORTH DEARBORN ST. t ions or others. DO NOT M ISS TIllS OPPOR ­ T UN ITY OF ACQUIRING A RADIO RECEIVER THAT MEETS A I.L DEMANDS. YOU W IL L A. @ T. RADIO COMPANY WONDER AT TIlE MONgY-G IVING VALUE CHICAGO, ILLINOIS BE HIND OUR OFFER! Dept . B. DANVERS, MASS.

Always M ention RADIO AGE W hen W ritillg to Advertisers 52 RADIO AGE for June, 1924 The .J.1iagazine of the Hour Corrected List of U. S., Cuban and Canadian Broadcasting Stations

WABO Lake Avenue Baotist Church ...... R ochester . N. Y. 252 WGAL L a ncaster Electric Supply & Construction Co ...... L a ncaster. Pa. 248 WABP Robert F. \Veinig ...... Dover. Ohio 266 WGAN WABQ H averford College. Radio Club ...... H a verford. Pa. 261 WGAQ 81~~\v~~dL~0Id~;" C·o·;P.·.·(\V : 'G: 'p~it ~ ~ ~'; ';i:::::::::: ~~~:;~g~~·t. ~:: m WA BR Sco~t Hig h School. :-:I. \V. R . F o ley ...... Toledo. Ohio 270 WGAW WABS E s sex l\.l a nufacturing Co ...... Newark, N. J . 244 WGAZ ~~~~~t B~;,dA 1.p~it~~ ~·: : : : : : : : : : : : : : : : : : : : : : : : : : : : s;'~ il; AAt~~~.a·I~3: m WABT H o liday-H a ll, R adio E ngineers ...... \Vashington, Pa. 252 WGI Amencan Radio & Research Corp ...... Medlord Hillside. M ass. 360 WA BU Victor Talking M ac!.ine Co ...... , ...... Camden. N. J. 226 WGL WA BV John H. De Witt. Jr...... Nashville . TenD. 263 WGN 1-~~mCa~ic~g~' Frib~ ~~t':"' Edge;~';te~' B ~~~ h' 8~;,~d~~~i i;,~h~\~~r~~~ia. Pa. 360 WA BW 234 Chicago. Ill. ' 370 WABX ~~~~~e B~f J~~~ s t e ~::: : :'::::::::::::::::::::: :j\ii.· Cfe~oes~ ~ ~.~~~~ 270 WGR WA BY John Maga ldi. Jr...... Philadelphia. Pa. 242 WGV f~~%~;tI "J1~~~~rce &.~~ ~ ~~~~ P~ .C~:'.'.'...... '...... ~e ,~~~~o,;n~'L;;: ' m WA BZ Coliseum Place Baptist Church ...... Ncw Orleans. La. 263 WGY WBAA Purdue Unive rsity ...... ,. .. W est Lafayette. Ind. 360 WHA 3~~;:~~i~le,;t{~iC;~~ ;' ~ ;'; : .'.'.'.'.'.'.'.'.'.- .'.' .'.'.'.'.'.'.'.'.'.- . SchertacJf~t~.Nw~: m WBAH The D ayton Co ...... Minnea polis. Minn. 417 WHAA WBAN Wireless Phone Corp ...... Pater son. N. J. 244 WHAB ~\:~'lc UW~v'¥h~~~~o~O\~~: : : : : : : : : : : : : : : : : : : : : : : : : d~'::s t~~:·.fe"x~ ~ ::~ WBAO James l\.lillikin U niversity ...... Deca tur. Iit 360 WHAD Marquette University ...... M ilwaukee. Wis. 280 WBAP \Vo rtham-Ca rter Publi shing Co. (Star Telegra m ) . ... Fort Worth. Tex. 476 WHAG W BAV 390 WHAH }i~}~~rs~~p~~y CiC~~~~~~i.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.' .'.'.' ? nS~~li~: ~~~ m WBAX .fo"h~rH~S~~~;~~jr~~· :.'.'.'.'.':.'.'.'.'.' .'.'.'.'.'.'.'.':.'.'.' .'.' . \\~I~~:::~~:~e?;~~ 360 WHAK Roberts H a rdwar e Co ...... Clarksburg. \V. Va. 258 WBAY " 'este rn Electric Co...... New York. N. Y. 492 WHAM Univer sity of R ochester (Eastman School of Mus ic) ... R ocheste r. N. Y. 283 WB BA Newark R adio L a bora tories ...... Newark . Ohio 240 WHAP Otta & Kuhns ...... •...... Decatu r. Ill. 360 WBBD 234 WHAR Paramount Radio & E lectric Co. (W. H. A. Pulus) WBBE 246 Atlantic City. N. J. 231 WBBF 270 WHAS Courier-Journal & Louisville Times ...... Louisville. Ky. 400 WBBG ~~f!~~~;Jgt~~~~~~ei;~~ i:~:g/:::::'::::::::::::::::::::::: :·.':··;; :~:t::1~~i~t·~t 240 WHAV Wilmington Electrical Specialty Co ...... \Vilmington. Del. 360 WBBH J. Irvi ng B ell ...... P o rt Huron. Mich. 246 WHAZ Rensselaer Polytechnic Institute ...... •...... Troy. N . Y. 380 WBBJ 258 WHB Sweeney School Co ...... K a n sas City. 1\10. 411 WBBL lj~!~::~~t;~~~~":;e~b:;::i~'; ·Ch~·r ~h·. '. '. '. '. '. '. '. '. ,,:~ s.t . P~r:;h~e;~~: \!!: 283 WHK R adiovox Co. (Warren R. Cox) ...... •.• ...... C leveland. Ohio 360 WBBM Fra nk A tlass Produce Co ...... Lincoln. Ill. 225 WHN George Schubel...... "iew York. N. Y. 360 WBBN Bla ke. A. B ...... Wilmingto n. N. C.' 275 WHO Ba nkers Life Company ...... Des Moines. Iowa 526 W BBO Mich. Limestone & Chemical C o ...... '...... Rogers. Mich. 250 WIAB J oslyn Automobile Co...... Rockford. Ill. 252 WBBQ Fra nk Croo k ...... '...... Pawtucket. R. I. 252 WIAC WBB R P eoples Pulpit Asso ...... Rossville . N. Y. 244 WIAD WBBS Firs t Baptist Church ...... New Orleans. La. 250 WIAF ~~~;~~of·~&i~:i·;,:.·· .··.··.:.··.:.··.:.·· ..· ..·.·· ..·.: ..· ..·.:.:.:.:.:.:.:~:.:.:. :. l~l~t~r~,;~~~r U! WBBT Lloyd Brothers ...... '" . . Philadelphia. Pa. 234 WIAH Continental Radio & Mfg. Co ...... Newton. Iowa 258 WBBU J e nks Motor Sales Co ...... Monmo uth. Ill. 224 WIAI H eey Stores Co ...... Springfield. Mo. 252 WBBV J o hns town Radio Co ...... Johnstown. Pa. 248 WIAJ Fox River Valley Radio Supply Co. (Quinn Bros. ) . .. •.. Neenah. \-Vis. 224 WB BW Ruffne r Junior Hi~h School...... Norfolk. Va. 222 WIAK WBBY \ Vashin gton Lig ht Infa ntry. Co. " B " 11 8th Inf ...... C h a rles ton. S. C. 268 WIAO ~~h~~f~Pl;?~~:;: :,:'ri~ ~'';i Mil~~~';kee: : : : : : : : : : : : : : : . M~,~a~hkaee ~\tr~~: m WB BZ 227 WIAQ WB L ~ o~I'ih~~di~ oC,;,- ...... ' ...... '.'.' ...... ' ...1 .n1~~~~~~~isK~':t~: 261 WIAS ~~~~i~lecrri~liC~i.~~ . :~ ..'.'.'.'.'.' .'.'.'.'.'.'.':: .'.'.'::.'.'.'.'8 ~~~~~:,o:.. I~~~'; ~~: WBR P e nnsylva nia Sta te Police ...... Butler. Pa. 286 WIAT L eon T. Noel...... - ...... •...... T a rkio. Mo. 360 WBS D. \V. M ay. Inc ...... Newark. N. J. 360 WIAU American Trust & S a vings Bank ...... Le Mars. Iowa 360 WBT Southern R adio Corp ...... C ha rlotte. N. C. 360 WIAY WBZ W e'tinghouse E lec. & !'vHg. Co ...... Springfield. M ass. 337 WIK yf.&t,: aE1e~rY2~~~P(H~;b~~t·F: 'Ke i ~o an~i Hu;'ie;Vrl~~h~~~':;)D. c. 273 WCA D St. Lawrence U niversity ; .-...... Canto n. N. Y . 280 M cKeesport. Pa. 234 WCAE 462 WIL Continental E lectric Supply Co ...... Washington. D. C. 360 WCAG lfl~':Iemt.~R!d~fi~~ .~~'.'. '.'. '. ' . ' ...... N~~ tO~ le'1;;. r:: . 268 WIP Gimbel Bro thers ...... Philadelphia. Pa. 509 WCAH Entrekin E lectric Co ...... : . .. Columbus. Ohio 286 WJAD J ack.on·s R adio Engineering Laborato ries ...... , . \Vaco. T exas 360 WCAJ Nebr aska W esleyan Unive r s ity ...... U niversity Place. Nebr. 360 WJAG Norfolk Daily News ...... •...... Norfolk. Nebr. 283 WCAK Alfred P. D a niel...... H ouston. T exas 263 WJAK WCA L St. O laf College ...... Northfield. Minn. 360 WJAM f}.i~~~e~ha:.h.i~~ ...... ·.·.·.·.·.·.·.·.·!·.·c~J;~efu!gid~: I~~'; m WCAM 360 WJAN Peoria Star ...... •.•.•.....•.....•....•...... Peoria. Ill. 280 WCAO ~~l~d~~~a& CS'l!~~~;,' C·o·.:::: ::::::::::::::: ::: :::: :B~m;',,~~:"Jt 360 WJAQ Capper Publications ...... ••.•••.•..•...... Topeka. Kans. 360 WCAP Chesapeake & Potomac T elephone Co ...... Washington. D . C. 469 WJAR The Outle t CO. U. Samuels & Bro.) ...... Providence. R. I. 360 WCAR Alamo Radio E lectric Co ...... San Antonio. Tex. 360 WJAS Pittsburgh Radio Supply House ...... Pittsbur!!h. Pa. 250 WCAS William Hood Dunwoody Industria l Institute .... Minnea polis. Minn. 246 WJAT K elly-Vawte r Jewelry Co...... Mars hall. Mo. 360 WCAT South Dakota Sta te School of Mines ...... Rapid C ity. S. Dak. 240 WJAX Union Trust Co ...... Cleveland. Ohio 390 WCA U Durham & Co ...... Philadelphia. Pa. 286 WJAZ Chicago R adio Laboratory ...... Chicago. Ill. 448 WCAV J. C. Dice E lectric Co ...... Little Rock. Ark. 360 WJD Richard H . Howe ...... Granville. Ohio 229 WCAX Univer sity of Vermont...... Burling ton. Vt. 360 WJX Deforest Radio Telephone & Telegraph Co ...... New York. N. Y. 360 WCAZ Carthage College ...... Carthage. 111. 246 WJY R. C. A ...... New York. N. Y. 405 WC BA Charles W . H eimbach ...... Allentown. Pa. 280 WJZ WCBC Univers ity o f Michi~ a n ...... A nn Arbor. Mich. 280 WKAA ~: ft,;~;.'.'.'::::::::::::::::::::::::::::: ::: :C·e~: ~vR~~~~;.1;,,~~ ~~~ WC BD Wil bu r G . Voliva ...... Zion. 111. 345 WKAD Chas. Looff (Crescent P a rk) ...... •...... East Providence. R. I. 240 WC BE Uhah R adio Co ...... New Orleans. La. 263 WKAF WC BF Paul J . M ill<- r ...... Pittsburgh. Pa. 236 WKAN ~riit~d ~~~:~r;'M'.,r:~ c?Co:: .' .' : .' .' .' :: .':.' : :.' :.'.'.' ~:~~;t:a~:~y::"1~ ~' m WCBG How, rd S. \Villiams (Porta ble) ...... Pascagoula. Miss. 236 WKAP Dutee W . Flint ...... Cranston. R. I. 360 WCBI Nico'}. Dunca n & Rush ...... Bemis, T ennessee 226 WKAQ Radio Corp. of Porto Rico ...... San Juan. P. R. 360 WCBJ J . C. Mans ...... Jennings. Louisiana 244 WKAR Michigan A lgriculture College ...... E ast Lansing. Mich. 280 WCB K E. Rich-. r d Hall ...... St. P ete r sburg. Fla. 266 WKAS L. E. Lines Music Co ...... •...... Springfield. Mo. 360 WCBL 280 WKAV Laconia R adio C lub ...... Laconia. N. H. 254 WCBM ~~~~7:~ ns~~~~~ .~~~'. :~'. '.'. '.'.'.'. '.'. '...... ·.·B :ttY~~~~.' ~d: 229 WKAY B ren a u College ...... Gainesville. Ga. 280 WCB N J ames P. Bola nd ...... Ft. Beni. H a rrison. Ind. 266 WKY WKY Radio Shop ...... Oklahoma. Okla. 360 'WCBO The Radio Shoo. Inc ...... Memphis. Tenn. 250 WLAG Cuttin!! & Washington Radio Corp ...... l\linneapolis. Minn. 417 WCBQ Firs t Baptis t Church ...... Nashville. T enn. 236 WLAH Samuel Woodworth ...... Syracuse. N. Y. 234 wrR R TTniversitv of Mississiopi ...... near Oxford. Miss. 242 WLAJ Waco Electrical Supply Co ...... •...... Waco. Texas 360 WCBR Charles H. Meester (Por table Station) ...... Providence. R. I. 246 WLAK Vermont F a rm M achine Corp ...... •. Bellows Falls. Vt. 360 WC BT C lark Unive rsity. Collegia te Dept...... Worcester. M ass. 238 WLAL Naylor Electrica l Co...... Tulsa. Okla. 360 WC BU Ar ... " ld Wireless SUDply Co ...... A rnold. Pa. 254 WLAP W . V. Jordon ...... •.••...... Louisvllle. Ky. 360 W CBV Tull" homa R adio C l ub ...... Tullahoma. T enn. 252 WLAQ WCBW G eorge P. Rankin. Jr .• and Maitland Soloman ...... Macon. Ga. 226 WLAV ~ r!~t':-fc 1§-ho~~i~l.i~~::.'::::::.'.':::: ::::::::::.-.': ~~~~~~~~ia.M~1~: m W CBY The Forks E lectrical Shop ...... Ruck Hill Falls. Pa. 268 "'LAW Police D ent.. City of New york ...... New York. N. Y . 360 W CBZ Coppotelli Bros. Mus ic H o u se .... , ...... Chicago Heights . Ill. 248 WLAX Putnam Electric Co. (Greencastle Community Broadcasting Station) WCK Stix. Baer & Fulle r Dry Goods Co ...... St. Louis. Mo. 360 G reencastle. Ind. 231 WCM Unive r sity of T exas ...... Austin, T exas 360 WLB University of Minnesota .••...... •••.•...... ·.. Minneaoolis. Minn. 360 wex D etroit Free Press ...... Detroit. Mich. 517 WLS S ears. Roebuck Co ...... • •...... Chicago. Ill. 345 WDAE T a mpa Daily Times ...... Tampa. Fla. 360 WLW C rosley Manufactu ring Co ...... •...... C incinna ti. Ohio 309 WDAF K a n sas City Star...... Kan sas City. Mo. 411 WMAB Radio Supply Co ...... Oklahoma. Okla. 360 WDAG J. L a urence M a rtin ...... Amarillo. Tex. 263 WMAC J. Edw. P age (Olive B . Meredith) ...... Cazenovia. N . Y. 261 WDAH Trinity M ethodis t Church (South) ...... El Paso. Tex. 268 WMAF Round Hills Radio Corp ....•...... •...... Dartmouth. M ass . . 360 WDAK The Cou ra nt ...... •...... H a rtford. Conn. 261 WMAH General Supply Co ...... Linco ln. Nebr. 254 WDAO Automotive E lectric Co...... D a llas. Tex. 360 WMAJ Drovers T elegra m Co...... Kansas C ity. Mo. 275 WDAP B ,ard of Trad e ...... Chicago. Ill. 360 WMAK Norton Laboratories ...... • ...... L ockpo rt. N. Y . 360 WDAR Lit Brothers ...... Philadelphia. Pa. 395 WMAL Trenton H a rdwa re Co...... Trenton. N. J. 256 WDAS Samuel A. Waite ...... •...... Worceste r. Mass. 360 WMAN First Baptist Church ...... Co lumbus. Ohio 286 WDAU S locum Kilburn ...... ;\I'ew Bedford. M ass. 360 WMAP Utility Batte ry Service ...... •...... E aston. Pa. 246 w nAY Radio Equipment Corp ...... Fargo. N. D ak. 244 WMAQ C hicago D a ily News ...... Chicago. Ill. 448 W DBA Fred R ay...... Colum bus. Ga. 236 WMAV Alabama Polytechnic Institute...... Auhurn. Ala. 250 W DBB A. H. White & Co .• Inc ...... _ .. Taunton. Mass. 229 WMAY Kings highway Presbyterian Church ...... St. Louis. M o. 280 w nBC Kirk. J o hnson & Co ...... L a n caster. Pa. 258 WMC "Commercia l Appeal" (Commercia l Publishing Co.) .. Memphis. Tenn. 500 W DBD Herman Edwin Burn' ...... Martinsburs::. W. Va. 268 WMH Precision E Quipment Co ... .•...... •.. Cincinnati~ Ohio ' 248 WDBE Gilham-Schoen E lectric Co ...... •...... A tla nta . Ga. 252 WMU Doubleday-Hill Electric Co ... .••••...•...... Washington. D. C. 261 W DBF 246 WNAC Shepard Stores . ..•...... •...... Boston. M ass. 278 WDBH ~.0~~r§cl?er:.h2~~s. ~ : : : : ~ ~ : : ~ : ~ '. : '. : : : : : : : '. : : : '. : \({r'!,~~~~~~;" 8~~~: 268 WNAD University of Oklahoma ...... • ...... Norman. Okla. 360 WDBI E. Budd Peddicord ...... New Orleans. La. 242 WNAL WDBJ R ichard son W"yhnd E lectr ic Corp ...... Roanoke. Va. 229 WNAM ~eli fg~~~:l~ ~' ·C~.'.·.·.· ...... ·.·E~a~;~iiie.Nf~J: ~:~ W DRL Wisc. D ept. of M a rket s ..•...... Steven s Point. Wisc. 278 WNAN Syracuse Radio T elephone Co ...... Syracuse. N. Y. 286 WDBN Electric Light & Pow<- r Co...... Ba n gor. Me. 252 WNAP Wit tenbe r g College ...... Sprinl(field. Ohio 231 WDM Church of the Covenant ...... , " ...... Washin!!ton. D. C. 234 WNAQ Charleston R adio Electric Co...... Charleston. S. C. 360 WDZ James L. Bush ...... Tuscola. Ill. Star Store Bid!!. 278 WNAR C. C. Rhodes ...... Butle r. Mo. 231 WEAA F. D. Fallain ...... Flint. Mich. 280 WNAS T exas R a dio Corp. & Austin State91l'"n ...... Austin. Texas 360 W EAF American Telephone & Telegraph Co ...... New York. N. Y. 492 WNAT Lennig Brothe r s Co. (Frederick L enni!! ) ...... •.. .. . Philadelphia. Pa. 360 WEAH Wichit" Board of Trade ...... •...... Wichita . Kans. 244 WNAV Peoples T elephone & T elegr aph Co ...... Knoxville. Tenn. 236 WF.AI Cornell Unive r s ity ...... • ••••...... Ithaca. N. Y. 286 WNAW Peninsular Radio Club (Henry Kunzm a nn ) ...... Fort Monroe. Va. 360 WEAJ University of South Dakota ...... Vermilion. S. Dak. 283 WNAX D a kota R adio Apparatus Co...... Yankton. S. Dak. 244 WEAM Borough of North Pla infield (W. Gibson Buttfield) WNJ Sholton R a dio M a nufacturing Co...... Albany. N. Y. 360 North Plainfield. N. J. 252 WOAA WEAN Sl.epard Co ...... Providence. R. I. 273 WOAC R~u~~~JioH'g~:: ...... •.:: .... : ..: . .:: .. :. ~~dri~~: ~~~ m WEAO Ohio State Unive rsity ....••...... •....•...... Columbus. Ohio 360 WOAD Friday B a tte ry & Electric Corp...... •.•.••.. Sigourney. Iowa 360 WE"P Mobile R ad io Co ...... Mobile. A la. 360 WOAE Midland College ...... • . •...... ••.•..... Fremont. Nebr. 360 W EAR The Evening News Publis hing Co ...... Baltimore. Md. 261 WOAF Tyler Com mercia l College .•...... Tyler. T exas 360 W EAU David son Bros. Co ...... S ioux City. Iowa 360 WOAG Apollo Theate r (Belvedere Amusement Co.) ...... Belvedere. Ill. 224 W EAY Iris Thea tre (Will Horowitz. Jr.) ...... H ouston. T exas 360 WOAH Palmetto R a dio Cor p ...... • , ...... Charleston. S. C. 360 WEB Benwood Co ... : ...... •...... St. Louis. Mo. 273 WOAI Southern Equipment Co ...... San Antonio. Texas . 385 WEV Hurlburt-Still Electrical Co ...... Houston. T exas 360 WOAN Vaughn Conservatory of Mu . ic (Jame. D. Vaughn) WEW St. Louis U nive r sity ...... •. . . •...... St. Louis. Mo. 261 . . L awrenceburg. Tenn. 360 WFAA Dallas News & Dallas Journol ...... Dallas. Texas 476 WOAO Lyradion Mf!!. Co ...... Mishawaka. Ind. 360 WFAB Carl F . Woese ...... Syracuse. N. Y. 234 WOAP Kalamazoo College ...... •...... Kalamazoo. Mich. ' 240 WFAF H. C. Spr a tley Radio Co...... Poughkeepsie. N. Y. 360 WOAQ Portsmouth Kiwanis Club ...... ••...... Portsmouth. Va. 360 WFAH E lectric Suoply Co...... Port A rthur• . Texas 236 WOAR WFAJ Hi-Grade \Vireless- Ins trument Co ...... Asheville. N. C. 360 WOAT }t~~JY J.. k~~~~~~":.' :: .. .'::.'.' .. .'.' .. .'.' .. :.'.'.'.'.'.'.'.'.'.' .'\vifn'ir,:':tl~~. l:';~t m W FAM Time. Publi.hing Co ...... St. Cloud. -MInn. 360 WOAV Pennsylvania National Guard. 2d Battalion. 112th Infantry . . Erie. Pa. 242 WFAN Hutchinso n E 1pctric ~f"rvic e Co ...... •...... Hutchinson, Minn. 360 WOAW Woodmen of the W o rld ...... ••... Omaha. Nebr. 526 WFAQ 1\1 issollri \V e ~ l ('vn n College ...... •...... Cam eron~ Mo. 360 WOAX Fra nklyn J. Wolff ...... Trenton. N. J. 240 WFAT -New Columbus Colle!!e ...... Sioux Falls. S. Dak. 258 woe Palmer School of Chiropractic ...... •.••••• •• D a venport. Iowa 484 WFAV Uni_roity of Nebraska. Department of Electrica l Engineerins:: WOI Lincoln. Nebr. 275 WOK ~1~e"B1~aJec~~I~e.~e.':.':.'.'.'.': :.':.' . ·.':.'.'.':.'.':::::.':.'Pi·,;::-'~ff. ~~~ m WFI f'trawbridge & Clothier ...... •••..•...... Philadelpbia. Pa. 395 WOO John Wanamaker...... •...•.•...... •. ..•. , ... Philadelphia. Pa . ••599 RADIO AGE for June, 1924 The Magazine of the Hour 53 Pickups & Hookups A Condenser That Cuts (Continued from page 33.) Losses was so low that I couldn't get any point of regeneration because the last hookup I tried from still another magazine shorted my A battery. I had it charged, and was all ready to try to set Wednesday evening fol­ lowing, and the first station I received was KFKX of Hastings, Neb. Here are the following stations I received from 8:30 P. M. to 1 :30 P. M. of the same evening. Some of these Famous Guaranteed Quality and Service­ stataions were testing, and it is also Backed by Years of Successful Manufacture and known that Pasadena is very hard Thousands of Satisfied Usel·s. on radio reception due to the moun­ Prices That Save and Satisfy tains-but just take a slant at this: Auto Batteries Radio Batteries GoVolI 11 Plat'>. $12.25 ~:~g:::8 :~g~: $1~:~g o KFKX, KDYL, KGG, CYB, 6o J!)lt 13 PI:ite. 14.2S 6-Volt 100 Amps. 12.50 CKCB, CFCN, KFCB, KFAW, lz.volt 7 Plate, 17.00 ~:~g:l i~g ~::::g~: i~:gg Special2-Volt Storage Battery for W.D.ll and 12 tube •. KPO, KFNV, KLX, KGO, KFKB, WilIl'un 200 hours on one char ge. Recha~geabl e. $5_00. Special4-Volt Storage Hatt ery for U .V.199 tube•. Same and all local stations on loud speaker! feature. as 2 Volt. $8.00_ Stationary variocouplers and adjust­ Shipment express C.O_D. s ubj e~t to examinatiotl. 5')'; Di.count for cash in full with order. able bakelite-WOW!! I'll tell the 2.Yr. Guarantee Bond in Writing world RADIO AGE is no joke. I'd G. M. Proudfoot, engineer for the Cru­ With Each World Storage Battery proves satisfactory World performance. Mail this ad like to make a six-stage amplifier ver Manufacturing Company, has de­ with your name and address and we will ship battery day order is received; and gi.,e you a 45 -Volt " B" Bgttery and and yell into the mouthpiece "Three signed a new condenser for the purpose of Hydrometer Free with each battery cheers for RADIO AGE !"-because reducing losses and inefficient capacities. purchased. Write today. I don't think the yell I can emit is World Battery Company The new condenser, s how n above, Dept. 36.1219 S. Wabash Ave. loud enough for a book like that! CHICAGO. ILL. Y ours very truly, achieves its aim by means of stator plates CLARENCE EASTON. mounted on two rods, instead of the tra­ 35 South Raymond, Room 320, ditional three. Bradley Bldg., Pasadena, Calif. This model was used recently in a trans-Atlantic test of a "low-loss" tuner See Page 36 for Special June designed by F. ]. Marco, of station Offer for Reinartz Fans! And while you are still laughing at that A Real Radio Bargain! one, we'll get next month's issue ready. 9X BA, Chicago. The condenser loss was S'long. only 7-1 ,000 of one per cent. ERLA BLUE PRINTS Erla Receivers out-distance other .sets with an almost unbelievable volume and a naturalness that cannot be distinguished from the source of reception. This is the famous Erla Reflex Hook-up. Less than one year old-but has taken the entire nation by storm. Every listener-in raves about it and wants a set of his own immediately. So easy to construct that anyone who can handle a screw driver can build the set complete, in a surprisingly short time-about 1% hours. Everything is so simple and easy. NO SOLDERING WHATEVER-ONLY A SCREW DRIVER NEEDED The results from the Erla 3 tube is naturalness itself and cannot be improved upon. Actual size working diagrams make everything simple and easy. Every piece of apparatus and evet;y wire is pictured in its exact place-every a'rtic1e needed is listed on the diagrams. Diagrams sent same day your order is received. Send P. O. or Express Money Order or Bank draft or Bank Cashier's check. Do not send stamps or personal checks.

Erla Hook-up Diagram Prices 3 sheets for making 1 tube set 25c 3 sheets for making 2 tube set 3Sc 3 sheets for making 3 tube set SOc Frank D. Pearne Sole Distributor of Erla Diagrams for U. S. and Canada 829 Waveland Avenue, Chicago, Ill. Dealers, Write fo~ Qu ~nt ity Prices Always Melltion RADIO AGE When Writing to Advertisers 54 RADIO AGE for June, 1924 The Magazine of the Hour Corrected List of U. S., Cuban and Canadian Broadcasting Stations

W O Q \Veste rn R a dio Co ...... •...... •.••...... K a n sas City. Mo. 360 WSAD J. A. Foster C o ...... •...... •...... Providence. R. I . 261 W OR 405 WSAG City of St. P e te r s burg (Loren V. Davis ) ...... St. P ete r sburg. Fla. 244 WOS ki i :'~'.':r~es~;~ e &Mc;,~k e ti'; i:' B ·ur·e;'~; . · ...•....•...•.•...... J .., ffe·r~,;:'g~ y. NM~: 441 WSAI United Sta tes Playing C a rds Co ..•...... Cincinna ti. Ohio 309 W PAB 283 WSAJ Grove City C ollege ...... •...... •...... Grove City. Pa. 360 W PAC b~':,~i~~':,':.ni~;Jr~e C~~ ~I ~~~: :: : : : : : : : :::::::: : : : : ~g~ ::n ~~~:.geo ~ ~ : 360 WSAN A llen town R adio C luh ...... •.•.•••.•...... A llentown. P a . 229 WPAJ Doolittle Radio Cor p ...... ; .. •...... New H aven . Conn. 268 WSAP Seventh D ay Ad ventist C hurch .....••.•.•••... . New York. N. Y. 263 W PAK Nor th Dakota Agricultur a l College .... . Agricultural College. N. Dak . 360 WSAR D ou g hty & W elch E lectrical C o ...... •..••...... F a ll Rive r. M a s s. 254 W PAL Superior Radio & Telephone E quip m ent Co ...... Columbus. Ohio 286 WSAT D onohoo· Ware H ardware Co ...... Plainview, T exa ~ 268 W PAM 360 WSAW J o hn J . Lon g. Jr ...... C a n a ndaig u a . N. Y. 275 W PAP *~~~~~;~ f} c;,~IUi~~" : .. : ...... : : .. .. : ...... : .... : .. : .... : \J;~g~~;ter~K~: 360 WSAX C hicago Radio L aborato r y ...... Chicago. III. 268 W PAR Ward Batter y a n d Radio Co ... ••.•••••..••..• . . .•. . .. Beloit. Kan s. 236 WSAY Irving A u stin (Po rt C heste r Cham ber of C o mmprce). P o rt Cheste r . N. Y. 233 W PAT S t. Pat ricks Cathed r al ...... • •••••• • ••••...... E I P aso. Texas 360 WSAZ Chas. E lectric S hop ...... Pomeroy. Ohio 258 W P A U 360 WSB A tla n ta J o urnal...... Atla nta . Ga. 429 W PAZ fo,,~;oR~ i K~~lI er6~:)·.·. ·. ·.·.·:.·. ·.·.·.·.·.·:.·.·.·:::.·:.·. ·.·. ·C~~lers~~~~ · Wr-.:i{}~: 273 WSL J . & M. E lectric Co ...... Utica . N . Y. 273 W QAA 360 WSY Alabam a P ower Co ...... Birmingham. Ala. 360 W QAC ...... ". "...... :.:.: 234 WTAB F a ll Rive r D a ily H e ra ld Publi shing Co ...... Fall River. Mass. 248 W QAD !::~:~6'i~~~:;:~ ! ~~ 0:~$~~~~ r ~~[~~ 242 WTAC P enn Traffic C o ...... J ohnstown. Pa. 360 WQAE M oore R adio News S ta tion (Edmund B. M oore) ..... S p ri n gfi eld. Vt. 275 WTAF L o uis J. Gallo ...... N ew Orleans. L a . 242 W QAF Sandusky Register ...... Sand u sk y. Ohio 240 WTAG K e rn Music C o ...... Providence. R. I. 258 W QAL Coles County Telephon e & Telegraph Co ...... M attoon. III. 258 WTAH Carmen F e rro . ..•...... •.•..••••...... Belvede re. Ill. 236 WQAN Scran ton T imes ...... Scranton, Pa. 280 WTAJ T he R a dio Shop ...... •...... Portla nd. Me. 230 WQAO Calvary Baptist Chur ch ...... • . New York. N. Y. 360 WTAL Toledo R adio & E lectric Co ...... •...•...... Toledo. Ohio 252 W QAQ Abilene Daily R eporte r (West Texas Radio Co.) ..•• . . Abilene . T exas 360 WTAM Willa rd Sto r age B a tte ry C o ...... Cleveland. Ohio 390 WQAS P rince-Walte r Co ...... L owell. M ass. 266 WTAP Cambridge R adio & E lectric Co ...... Cambridge. III. 242 W QAX 360 WTAQ S. H. Van Gor don & S o n ...... •...... Osseo. Wis. 220 WRAA 369 WTAR R elia nce E lectric Co ...... N orfolk. Va. 280 WRAF 224 WTAS Cha rles E. E r bstein ...... •...... Elgin. III. 275 WRAH ~~i~:!§~~;;:\i;~~ :~: .·:.:. :.·:.:.: ..:.·: ..:.·:.:. :.:..:.:.:.:.:.:.: ..:. ·:.·:.: ..: ..;: :1~~1i~~1~~~ 231 WTAT Edison E lectric IJIumina ting Co ...... Boston. Mass. (portable) 244 W RAL Northe rn S ta tes Power Co ...... •...... St. Croix F a lls. Wis. 248 WTAU Ruegg B a tte ry & E lectric Co ...... T ecumseh. N ebr. 360 WRAM L omba rd College ...... ••...... ••...... G alesburg . III. 244 WTAU Ruegg B a tte ry & Eledric Co ...... •...... Tecumseh. Nebr. 242 WRAN B lack H a wk E lectrical Co ...... ••...... W a te rloo. Iowa 236 WTAW Agric ultura l & M echa nical C ollege of T exas ...•.. C olJege Station. Tex. 280 WRAO Radio Service Co ...... St. Loui s M o. 360 WTAX Willia m s H a rdware C o ...... : ... S treator. III. 231 WRAV A ntioch College ...... •..•..... Y ello w S prings. Ohio 242 WTAY loda r-Oa k L eaves Broa d dlstjng Sta tion ...... O a k P a rk. JII. 220 WRAW Aven ue R a dio Shop (Ho r ace D. G ood) ...... Reading. P a . 238 WTAZ Thomas J. M cGuire ...... Lambertville. N. J. 283 WRAX F laxon 's Gar age ...... Glo uceste r City. N. J. 268 WTG K a n sa s Sta te Agricultural College ...... • . M a nhattan. K a ns. 273 WRAY R adio S a les Corp ...... ••...... S c ra nton. P a . 280 WWAB Hoenig . Swern & C o . (John R asmussen ) . ..••...... Trer-ton. N. J. 220 WRAZ R adio Shop of Newar k (He rma n Lubinsky) ...... Newark. N . .T. 233 WWAC Sange r Bros...... Waco. Texas 360 WRBC Ima nuel Lutheran C hurch ...... Va lpa r a iso. Ind. 278 WWAD Wrig ht & Wrig ht (Inc. ) ...... ••...... Philadelphia. P a . 360 WRC R adio Cor por atio n of Am e rica ...... •...... W ashingto n •. D. C. 469 WWAE Ala mo D ance Hall. L. J. Crowley .... • ...... Joliet. I11. 227 WRK Doron B ros. E lect r ic C o ...... H a milto n. Ohio 360 WWAF G a lvin R adio Supply Co ...... Camden. N. J. 230 WRL U nion College ...... S chenectady. N. Y . 360 WWAO Michigan College of Mines ...... •••...... Houghton. Mich. 244 WRM U niver sity of Illinois ...... Urba n a . III. 360 WWI Ford M o to r Co ...... ••...... Dearborn. Mich. 273 WRR C ity of D a llas (police a nd fi re s ig n a l d e pa rtment) ...... D a llas. T exas 360 WWJ D etroit New s (Evening N ew s A ssn.) ...•.•••.•.•.... Detroit. Mich. 517 WRW Tarrytown Radio R esearch L a b o r a to ry (K oenig Bros. ) . T a rrytown. N. Y . 273 WWL 260 WSAB S o utheast M isso uri S ta te T eache r s College .•.... . Cape Gira rdeau. Mo. 360 WYAM ~1~~lr1c aynte~ ~~% ~ .;;". C·~.: : : : : : : : : : : : : : : : : : : : : : ~.e.,,: . ~Ii;~t· Ji:: 283 WSAC C lem son Agric ultura l College ...... Clemson C ollege. S. C. 360 WYAW C a tholic Unive r sity ...... •...•...•••...•.. Washington. D. C. 236 Canadian Stations C FAC Calgar y H e r ald ...... •. . .•...•...... C alga ry. Albe rta 430 CHCE Wes te rn Canada Radio Sup. (Ltd.) ...... Victoria. B. C. 400 CFCA Star P ub. & Prtg. C o ...... T o r onto. Onta rio 400 CHCL Va ncouve r M e rchants Exchange ...... ••.•••...... V a ncouver. B. C. 440 C FCF Mar coni \Vireless T eleg. C o. of C a n a d a ...... M o ntreal. Queb ec 440 CHYC Northern Electric Co ...... M o ntreal. Quebec 410 C FCH Abitib i P ower & P a p e r Co ...... • '" . Iroquois F a ll s. Ont. 400 CJCA Edmonton Journal...... Edmonton. Alberta 450 C FCJ La C ie d e L ·Even em ent...... Quebec. Quebec 410 CJGC L ondo n Free Press Prtg. C o ...... London. Ont. 430 C FCK Radio S up ply Co ...... E dmo nton. Alberta 410 CJCD T . Eaton Co ...... Toronto. Onto 410 C F C L Centennia l Methodis t Church ...... V icto ria. British Co\. 400 CJCE 420 C F C N W . W . G ra nt R a dio (Ltd. ) ...... ••...... C a lgary. A lbe rta 440 CJCI ~:~m~~aRa J};d~o r~~:·. ·.·. ·.·.·. ·. ·. ·.·.·.·.·.·.·.:·. S't : "j '; h.;:'M';\~uBe:~n~\;'i~i~ 400 CFC O Semmemhaack -Dick son (Ltd. ) ...... B ellevue . Quebec 450 CJCN Simo ns Agnew & C o ...... Toronto. Onto 410 C FCQ R a dio Specialties (Ud.) ...... •...•...... Vancouve r. B. C . 450 CJCX P e rcival W esley Sha ckleton .... .••....• ...... Olds. Alberta 400 C F C R Laure ntide Air Ser vice ...... S udbury. Ont. 410 CJSC Evening T elegram ...... Toronto. Ont. 430 C FCW The R a dio S h op ...... •...... L on d on. Ont 420 CKAC L a Presse Puh. C o ...... M ontreal. Quebec 430 C FDC Sparks Co ...... Nan a imo. B. C . 430 C FQC CKCD Vancouver D aily Province ...... Vancouver. B. C. 410 T he E lectric Shop (Ltd.) ...... •...... Saskatoon. S askatchewan 400 450 C FRC Queen s U niversity ...... Kingston. Onta rio 450 CKCE C. a n adian Independ. T elepho ne Co ...... T o ronto. Ont. CF UC U nive r s ity of M ont real. •• ...... Montreal. Q uebec 400 CKCH Can adia n National R a ilways ...... Ottawa 435 C HAC Radio E ngineers ...... • .. Hali fax. Nova Scoti a 400 CKCK L eade r Pub. Co ...... RegIna. Saskatchewa n 420 C H B C A l bertan P ub lishin g Co ...... Calgary. A lberta 410 CKOC Wentworth R adio S upply Co ...... H a milton. Onto 410 C HCD Can adia n W ireless & E lec. Co ...... • ...... Q ueb ec. Q uebec 410 C KY M a nitoba T ele;>hone S ystem ...... •. • •• . .••. .... Winnipeg. M a nitoba 450 Cuban Stations P W X Cuban Telephone Co ...... •...... • ...... H abana 400 2H,) 180 2 DW Pedro Zayas ...... •...... ••...... TI aban a 300 20L b~~ ~ / c~fta:d·~ ::::.·. : : : : : : '.: : : : : : : : : : : : : : : : : : : : : : : : : : : : : :~~g ~~~ 290 2A B Alberto S. de B u stamante ...... •...... Habana 240 2WW A m a d eo Saen z ...... H a bana 210 20K Mario Garcia Velez ...... •• . . ... Haban a 360 5EV 360 2BY 6KW 340 Frederick \V. Borton ...... H aban a 260 6KJ 275 2CX F rederick W. Borton ...... • . . • ...... H abana 320 6CX 170 2EV Wes tinghou se E lec. Co ...... '1aban a 220 6DW 225 2TW Roberto E. Ramires ...... Habana 230 6BY 300 2HC H eraldo de C u ba . ... : ...... •...... H aban a 275 6AZ 200 2L C Luis Casas ...... H aban a 250 6EV 225 2KD E. Sanchez d e Fuentcs ...... • ...... •...... H aban a 350 8AZ m~~~~~;~y ):;/y;V>< ,li[J~~ 240 2MN Fausto S imon ...... H abana 270 8BY Alberto R avelo . .•• ...... S tgo. d e Cuba 250 2M G Manuel G . Salas ...... "! aban a 280 8FU And res Vinnet ...... S tgo. d e Cuba 225 2JD Raul Perez Falcon ...... H aban a 150 8DW P edro C . Anduz ...••...... S tego. de Cuba 275 2Kt' A lvara Daza ...... H a b a na 200 8EV Edua rdo M a teos .•••••...... • , . • . • ....••...... S tego. de Cuba 180

Big Test Station Planned A new experimental radio station for a A REAL RADIO BARGAIN! more complete investigation of radio phe­ R adio Age Annual, the best hookup book. and one year's subscription-$3. If nomena and broadcasting will be opened you want this double bargain sign the coupon and mail at once. Send price by within the next few months by the Gen­ check. currency or money order. If by check add five cents for exchange. eral Electric Company, at an estimated Radio Age. Inc., cost of $150,000. 500 N ort h De:nborn Street The station will be built on land re­ C hicago cently acquired by the company in Sche­ Gentlemen : P lease sen d m e by return mail your illus tra ted Rad io A ge Annual. containing more nectady, N. Y. A power house capable of than 100 big pages of hookups a nd ins truc tio n s and also sen d m e Radio Age. The Magazine of the Hour. for one year. I e n close $3 . This w ill give me a o n e d o llar book and a $2.50 s ubscription at delivering high power at various fre­ Quencies will be erected. The antenna a saving of fifty rents. Please s ta rt my subscr iption with the ...... r. u m ber structures will allow a wide range of wave lengths, so that systematic investigation Nam e ...... _ ...... _ ...... _...... _ ...... can be made of the advantages of various wave lengths in solving the various prob­ Street Add ress...... _...... _ ...... _...... _...... _ ..... _ lems discovered daily in the radio field. • I The General Electric Company decided Ci ty ... _ ...... _ ...... _...... _...... _...... _...... _ ...... to erect an experimental station because the space available in the power house Stat e ... _ ...... _.. ___._ .. _ ... __...... _ ...... _ .. _ ...... _...... _ ...... _ ...... _...... _ ...... _...... _ _ .... . and operating section of WGY, the big If book alon e is desire :!. mar:': cross h ere 0 and e nclose $ 1.0:1 . If s ubsc ription only . mark cross broadcasting station, is not sufficient to h ere 0 a n d e nclose $2.50. permit test work without interfering with the regular programs. RADIO AGE for June, 1924 The Magazine of the Hour 55

~ Ol"!osta~ ,S::,...~~~'" 1'1 fS, ~ _,,' Cell " ,-ell' WORLD·S 00.,000.00 COMPANY GREATEST STANDS SQUARELY BACK OF EVERY HEADSET HEADSET Formerly $6.00, now $2.95, with Notable Improvements VALUE Longer Cord (full 5 feet), Stronger Magnets. Higher Resistance, Increase of Sensitivity, Perfect Tone Mates EVERY SET TESTED BY LICENSED RADIO OPERA TORS Send no money- (9rder on a g>os[,,-Card THE TOWER MFG. CO, : 98T BROOKLINE AVENUE, BOSTON, MASS. {~~ltQ?iljf s~i en~i/ic ~ ~

"GOOD SOLDERING MEANS GOOD RECEPTION"

eff Does the Work of a Torch Twice I yIt~Sizeand Th~ee J T,mes Its PrIce

You can't get real results from high grade parts unless they a re properly soldered. The Jiffy Blow T orch a nd Outfit will give you a red­ hot job and last you a lifetime. The torch is self-blowing and develops a n extreme heat of 2300 degrees F. under prio-electric tests. No pa rts to get out of order . Simply touch a match to the burner coil and the torch operates. IT CANNOT EXPLODE P a tent Applied For The ] iffy Torch and Soldering Outfit consists of Torch, Small Copper Soldering Iron, M etal Sta nd, Bottle of Non-corrosive Flux and String Solder. ASK YOUR DEALER FOR A DEMONSTRATION. Price, $2.50 If your dealer can't supply you, send stamps, cash, money order, or sent C. O. D. Apex StalTIping Co. Dept. AA, Riverdale, III.

Alwa ys mentioll RADIO AGE JVh en JVri ting tJ A dvertisers 56 RADIO AGE for J une, 1924 The Magazine of the 1J our The Why of the Super... Heterodyne ( Continued from page 20.)

the neutrodyne it seems logical that sim­ the writer has not seen any attempt at sirable and are comparatively simple and ilar increases in the ratios of heterodyne this method. This arrangement, of course, inexpensive accessories to the heterodyne transformers would be attended with would not increase the range, but would ci rcuit. equally improved results. With higher only strengthen the signals of the waves Every noise developed in the detectors ratios we would have greater grid poten­ passing through the radio frequency and radio stages is, of course, amplified tials per stage and greater amplification stages, and would probably act as an addi · with the voice and music by the audio for a given number of stages. Whether tional stage of audio amplification. stages, and with two or more audio stages thi s would work out as well in practice as the foreign pulsations become almost un­ on paper remains to be seep. Super-Regeneration bearable unless they are removed or re­ There have been a number of attempts duced by the filt er system. The greater Regeneration at combining the super-regenerative circuit the audio amplification, the greater will As ordinarily built in this country, the and the heterodyne, but so far not much be the necessity for an effective filter. tuning circuit and fi rst detector are of the real progress has been made. Instead of simple non-regenerative type and there­ using the conventional non-regenerative Antenna Insulation fo re contribute li ttle or nothing to the circuit for the fi rst detector tube, a super­ Good insulation is necessary and it rec­ amplification. In the European versions, regenerative circuit has been substituted, ommends that the wire be swung over a however, regeneration is generally used in thus greatly increasing the sensitivity and signal strength of the conventional hetero­ clear space if possible, with at least fi ve the circuit of the fi rst detector tube to feet clearance over all oQjects crossed. ga in increased ra nge and amplification. dyne. With a circuit of this type properly Number 14 solid, bare, copper wire, or T his may be of the sim ple feed-back type worked out we would have the maximum larger sizes, are recommended, since it has wi th an adjustable tickler coil placed in possible in radio reception, but this would low resistance and results in loud signals. inductive relation to the tuning induc­ be at the expense of control complication Stranded wire, though stronger, is not con­ tance, or it may be of the "tuned plate" and tuning diffic ulties. The super-regen­ erative circuit is complicated and critical sidered quite as good as solid wire. Insu­ order in which a variometer is placed in lated wire, he explained, is not especially the plate circui t of the fir st detector tube. alone, but wh en operated in connection with a heterodyne the difficulties of tuning detrimental, but costs more than bare The latter is the simplest and the more wire. From 50 to 150 feet is the usual common method. would make the circuit fit only for the expert operator. length recommended for broadcast recep­ While the addition of regeneration by tion ; longer aerials bring in stronger sig­ tickler or variometer does add consider­ nals, and are more certain to bring in ~b ly to the performance of the set, yet it Audio Amplification distant stations. But they also bring 10 h~s the objec tion of adding a third control. The heterodyne circuit proper ends at more interference, including static. As the controls are fairly simple in the the second detector tube, where the am­ usual circuit (non-regenerative) this addi­ plified radio frequency waves are con­ tional control is not a great objection when verted into audible sound frequenc y For Women Buyers one becomes experi enred in tuning the waves. If increased volume is then re­ The feminIne influence is commencing heterodyne, but still it is on e more control quired for the operation of a loud speaker, to make itself felt in radio. One large just the same. Instead of having two we must add the usual audio ampli fi cation manufacturer of loud speaker horns has controls we now have three, which in any circuit on one or more stages. There is received orders for thorite horns to be event is no worse than with the neutro­ no marked difference in the audio amplifi­ made in nine different pastel shades to dyne. cation system from that ordinarily used harmonize with the color schemes of It is likely that a simple regenerative with the simpler receivers, except that it boudoirs and the complexions of their circuit fo r the fi rst tube (without regen­ is highly desirable to use an independent owners. Dealers report that where a man erative controls) would be satisfactory, "B" battery for the audio stages, and when will insist on purity of tone and volume such as the common Colpitts type of dry cell tubes are used in the set, even a from a loud speaker, the women buyers "Ultra-Audion" or the "Wizard" described separate "A" filament battery is highly will devote just as much attention to the in the April issue of RADIO AGE . In desirable. coloring and design of the outfit. Inci­ such circuits, regeneration in the detec tor With a common "B" battery for both dentally, the loud speaker industry is as­ ci rcuit is controlled largely by the rheo­ the radio and audio amplification stages suming tremendQus proportions, 600,000 stat adjustment and in a se nse adds little there is likely to be much noise and distor­ horns and 90,000 complete thorophone to the complexity of tuning. tion due to the harmonics and minor oscil­ loud speakers being fixed as the 1924 pro­ Regeneration in the fi rst detec tor circuit lations taking place in the fir st part of the duction from one Chicago factory. must not be confused with the undesirable circuit. These undes irable pulsations and regeneration that we have taken so much "bumps" are ca rried directly into the audio pains to avoid in the radio frequency frequency tubes through the common " B" Navy's Radio Progress stages. It is desirable in the detector cir­ battery wires unless a special filter circuit The navy rec ognized the value of radio cui t, but must be avoided at all costs in is interposed. With a se parate "B" bat­ in 1899, when Marconi came to New York the radio frequency circ uit. Regeneration tery for the audio tubes, the bumps can with three radi o sets to aid in reporting in the first detector ci rcuit increases the only be ca rried in by induction and hence the yacht races between the Shamrock output of the first detector tube and in­ are not so noticeable. Direct wire connec­

N EVERY field of endeavor there is always a suprcmacy- t.he Crosley Trirdyn 3R3 and Crosley champion-a man, a product or a thing that takes T rirdyn 3R3 Special. the leadership, not by accident, but because of I actual merit. In the new industry of radio, a T h ese inst.ruments are thc latest radio engineering leader has already arisen-Crosley Radio R eceivcrs. triumphs- three tubc sets giving five tube effi ciency. There is nothing miraculous about the tremendous pop­ They contain the following attractive features : Tuned ularity of Crosley Instruments. They have taken their Radio Frequency Amplification, Regenerative Detector place at the top through proven performance, con­ reflexed back on the first tube, and an additional stage tinually giving perfect satisfaction where, perhaps, of Audio Frequency Amplification. radio disappointment had been purchased at a much They are non-radiating, thus entirely eliminating higher price. neighborhood interfcrcnce. For ease of picking up new and distant stat.ions, pcrfect calibration and cx­ In new inventions, new simplified devices and new treme select.i vit y, the Trirdyn is unexcellcd. ways and means of giving greatcr radio value at a lower price, Crosley has constantly led. As a result, The only differcnce betwccn the two models is in the the purchaser of a Crosley Radio R eceiver, knows that size and st yle of the CaLinets. The Trirdyn 3R3 he is getting the last word in radio perfection. Special is completely self-cont.aining, having places for the nccessary dry battcries, head phoncs and other This is evidenced by the fact that Crosley is building acccssories. more radio receivers than any othcr manufacturer in the world. Ovcr 200 expcrts havc t.horoughly tested the Crosley Trirdyn. T heir opinions are onc ancl thc same. "There Above are illustrated two good reasons for Crosley is no receiver to compare with it at an y price."

Licensed under Armstrong Regenerative Patent No. 1,113,111.9.

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AUDIO-VISUAL CONSERVATION at The LIBRARY of CONGRESS

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