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July 1, 192415 Cents a Copy

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$eIN THIS ISSUE:

1 iSuppressing the Carrier Waves iUnradiating the Single Circuit

Regeneration and Reflexe

A New System of Audio Frequency

Saving the Storage Battery's Life

Some Live Problems in Radio

YOU WILL UNDERSTAND THISMAGAZINE ---AND WILL LIKE IT

PUBLISHED TWICE A MONTH

42 MAVERICK SQUARE

THE DIAL "DE LUXE"

4 inch DialIn designing the TRU-FIX the manufacturer has goneinto every detail relative to requirements of Dials usedon Radio Instruments, and after many experiments withsprings, etc., adopted the last word in Dials-the spring -less TRU-FIX Dial.

21/2 inch DialTRU-FIX Dials are made of selected sheet brass .023 ofan inch thick. The edge is very thin with a gradualcontour to meet the panel and is finished in bright nickelwith 100 division scale running from left to right, etchedin the surface, inlaid with black enamel, thereby makingTRU-F1X DIAL easily read at all times.The Knob, highly finished, is made of Bakelite 1% incheshigh with bevel edge at base and is attached to dial witha flat spring device made into the dial itself.

EAST BOSTON, MASS.

DISTINCTIVE AND SELECTIVEThe patented spring feature under the knob is one of thesuperior points of this dial. You are always sure of atrue running dial, as it keeps the dial in perfect align-ment-always flush with panel, ensures perfect settingsas the dial is not disturbed by jars or other causes. Thisgives you a dial that is different and one that alwaysinsures a more selective tuning. Perfect control onportable sets. Other dials cannot accomplish this feature.Replaces the Vernier, as it can be moved forward orbackward to within one thousandth of an inch, withoutbacklash, and stays put.

3

Cross Section Tru-Fix Dials

WHY TRU-FIX IS A SUPERIOR DIAL1. Corrects out -of -alignment of shaft with panel byspring feature made into the diaL2. Corrects looseness of end play in any units used, suchas Variocouplers, Condensers, Rheostats, eta, by slightfriction on panel to take up this end play.3. Corrects overbalanced units where there is a loss offriction caused by poor assembly in their manufactureand incorrect balancing of weights and metals.4. Corrects loss of tuning adjustments, such as fading,etc., due to slight jars or vibrations, which allows thecondenser or variocoupler to rotate out of position, there-by losing the station being tuned.5. Corrects body capacity, as the metal of the dial actsas a shield when grounded. This can be done by settinga plug flush with panel and allowing the dial to touch itlightly, having the plug grounded.These Dials, on account of the above listed features, arethe only Dials to use on portable sets.

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CELERUNDUM RADIO PRODUCTS CO.Dept. 522, 170 SUMMER STREET BOSTON, MASS.

RADIO PROGRESSHORACE V. S. TAYLOR, EDITOR

Volume 1 Number 8

Contents for

JULY 1, 1924PAC E

SUPPRESSING THE CARRIER WAVE 5

A NEW SYSTEM OF AUDIO AMPLIFICATIONBOOSTING THE WAVE LENGTHDEVELOPMENT WORK PUSHED BY GENERAL ELECTRIC 9

REGENERATION AND REFLEX 11

COMMON SENSE IN SEVEN CHAPTERS 13

A POPULAR PERFORMER 14UNRADIATING THE SINGLE CIRCUIT 15

SOME SENDING STATION STORIES 18

SAVING THE STORAGE BATTERY'S 19

AMERICAN RADIO RELAY LEAGUE 21

CUTTING DOWN WAITS BETWEEN NUMBERS 23

FONE FUN FOR FANS 24SOME LIVE PROBLEMS IN RADIOEDITOR'S LOUD SPEAKER:

HURRAH FOR THE FOURTH 29DISCUSSING DISTORTION 29

DR. RADIO PRESCRIBES 30BROADCASTING STATIONS BROUGHT UP TO DATE 31

Don't miss the next issue of Radio Progress-Read about a New Method ofDispensing with All Your Batteries, "A," "B" and "C."

RADIO PROGRESS is issued on the 1st and 15th of each month by the Oxford Press at 8 Temple Street,Providence, Rhode Island. John F. O'Hara, Publisher. Yearly subscription in U. S. A., $3.00. OutsideU. S. A., $3.50. Single copies, 15 cents. Entered as second-class matter, April 4, 1924, at the Post Officeat Providence, R. I., under the Act of March 3, 1879. Address all communications to RADIO PROGRESS,8 Temple Street (P. 0. Box 728), Providence, R. I. Title registered at United States Patent Office.

The publishers of this magazine disclaim all responsibility for opinions or statements of contributorswhich may at any time become subjects of controversy.

Don't Miss the SummerFun

Local stations are as goodin summer as in winter.

ICS

If you are located within ten or fifteen miles of agood broadcasting station you might just as well geta crystal set now as wait until the winter. Staticthat bothers tube sets does not affect local broadcast-ing as received on a crystal. The RADICLEARcrystal set has no dials to turn nor slider to shift. Itis an unusually toned set.

Send us check or money order for $2.90 and wewill forward a RADICLEAR postpaid.

TAYLOR ELECTRIC CO.1206 BROAD STREET

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D,;alers, wr. te for Catalogues and Discount Sheets

Radio Dealers !Practically every Radio Fan who comes into your store will subscribeto RADIO PROGRESS, if you will keep a few copies on your counter.Those who won't subscribe will at least buy a single copy.

Why not ring up some of this business on your Cash Register?We will help you and will put you in touch with our distributor inyour territory.

You'll be surprised when you discover how big an item this businesswill amount to in the course of a year. And you take absolutely norisk, nor do you have to invest a single cent of capital.

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RADIO PROGRESS" ALWAYS ABREAST OF THE TIMES "

Vol. I, No. 8 JULY 1, 1924 15c. PER COPY, $3 PER YEAR

Suppressing the Carrier WavesNew Method of CombiningRadio and Audio Frequency

By VANCEONE of the difficulties which the same wave would be assigned to a new

amateur finds when he tries to comer.understand the why of radio is to get Getting the Proper Length

After the wave has been assigned, howa good understanding of the carrier does the station obtain it on their send -wave. The action of this vibration has ing equipment? This is done by meansbeen already explained, but will be of adjustments on their coils and con -briefly reviewed before showing how it densers. The coil, it must be remem-may be omitted. When a new broad- bered, acts like a weight, whereas thecasting station is designed, the owners condenser is a spring and the combina-apply to the radio inspector of their tion of the weight and the spring de -district, and he assigns to them a wave eide how fast the oscillation will be.length and a call signal, which may To get a slow oscillation, which is theconsist of three or four letters. The same as saying a long wave length,letters which he assigns are purely either the weight or the spring, or per -arbitrary. For instance, WBAP is in haps both, must be made large. If theForth Worth, Texas; WCAP in Wash- sending station, after checking up withington, and WDAP in Chicago. It is a wave meter which measures thegenerally understood that these letters length, finds that it is sending at tooare given out in an irregular manner long a wave length, then they remedyand no particular significance is at- the trouble by reducing the number oftached to them by the public. turns in the coil or cutting down on the

But when it comes to the wave length, number of plates in the condenser.then many people think that it has a After they have adjusted the apparatusspecial meaning. In this they are mis- to give the right wave length, the car -taken. There is no more connection be- rier wave is a continuous oscillation uptween wave length and location than and down and looks like Figure 1. Thisthere is between call letters and the wave is Obtained from the oscillationcompanies they represent. To be sure, tube. The height of the curve is deter -certain kinds and sizes of stations are mined by the loudness of the wave. Ifassigned certain bands of wave lengths. the station is a powerful one and usesBy a band of wave length is meant all 'big tubes and a high "B" battery volt -the different figures which lie within that age, then the current flowing into therange. A band from 360 to 400 meters aerial will be large and the height upwould include 365, 370, etc. But the and down will be great. The number ofexact figures of any station are decided waves per second depends only on theby the radio inspector in accordance frequency or wave length, and must con -with the schedule of stations near the form to that given by the government,new one. Of course, if in a certain state as just described.there is another 'station already work- Next the Audio Waveing at 450 meters it is unlikely that the Now suppose that some one starts

singing into the microphone. The vi-bration of the diaphragm in the trans-mitter will be irregular and shaped per-haps as in Figure 2. If you inspect avictrola record under a microscopeit will show a line like this.Here again, the height up and downrepresents the loudness, but the distancebetween peaks, which represents thetime or shows how fast the waves followeach other, is determined by the pitchof the note being sung. The high notescome rapidly, and so the peaks areclose together, but the low notes, sincethey are much slower in following eachother, are spaced a little farther apart.

Like a Soldier's ProcessionIt must not be thought that the

speed referred to means the velocity withwhich the sound travels. High notes

7fiv 'fffiFig. 1. Usual Carrier Wave

and low notes both cover the ground inthe same time. All ufusic will travel afifth of a mile in a second, so that ifyou hear the music from a loud band amile away you know it took five secondsto reach you. The pitch of the notedoes not depend on this speed. It isdetermined by the closeness with whichthe waves come together. It is like aparade of soldiers marching along insingle file. The whole parade moves atthe same speed, which may be threemiles an hour, but up near the head ofthe procession we have a company whichrepresents a high tone. These soldiers

li RADIO PROGRESS JULY 1, 1924

are marching one behind each other sothat they nearly step on each other'sheels. That will represent high C onthe piano. A little later in the line we

Fig. 2. Audio Wave Sung

find a company where the soldiers arespaced five feet apart. They are stillmarching just as fast, that is, threemiles an hour, but they don't pass usin the grandstand nearly as frequently.This corresponds to middle C as shamin Figure 3. Behind them is anotherlot which straggle along ten feet apart.Of course, this will represent the nextoctave lower. This is illustrated inFigure 4. The same thing applies toradio waves. A high frequency stationlike KDKA, which runs at 926,000cycles per second and a low speed stationlike KYW 560,000 cycles, both havewaves that travel seven times completelyaround the earth in a second. But inthe former case their soldiers are spacedclose together, whereas in the latter theyare more widely separated.

Audio on Radio WavesNow let us see what happens when

we impose the audio wave of Figure 2 onthe back of radio wave Figure 1. This isdone by the modulator tube in the send-ing station. The radio frequency comesin spaced just as before, but its loud-ness, as represented by the height upand down, is controlled or modulated bythe audio frequency. Notice that theupper line A is exactly the same as theaudio wave shown in Figure 2 and thatline B is again the same thing, exceptof course, since it is the lower limitof the wave, it is turned upside down.

Ct.osr. S..ocin r. Ton v.

Fig. 3. Soldiers Like Audio

Curves A and B do not appear at allin a real picture of the wave, as sentout from the station. They are shownin our sketch merely to assist the eyein seeing that the peaks of the radiowave form a curve just like that ofFigure 2. To get a true picture of the

radio wave, both A and B must berubbed out.

Like Surf at SeashoreA better picture of what is going on

may be conveyed to the mind if youimagine yourself at Atlantic City aftera big storm. The surf comes poundingin along the beach and in your hotelroom you can hear it thundering on theshore. Now suppose a friend opens andshuts a window. When it is wide openthe sound is loud. As he graduallycloses it, it dies out more and moreuntil when the window is shut tight thebooming of the surf comes in onlysoftly. If this up and down motion ofthe window is represented by the linein Figure 2, then the sound of the surfwill be shown by Figure 5. Here each

W./11 - Low Ton

Fig. 4. Men Have Separated

individual wave of the ocean corres-ponds to one of the radio waves in thesketch, while the general loudness cor-responds to lines A and B.

Like Ordinary StationThis operation, as just described, fits

all the ordinary broadcasting stations.But the University of Illinois, whichruns station WRM, has recently beentrying various experiments with the

1

Fig 5. Like 2 with Carrier

idea of eliminating the continuous car-rier wave illustrated by Figure 1. Itseems a waste of energy, both in the re-ceiving station and in the transmittingradio to have such a carrier going allthe time. They have developed a dif-ferent method of sending. Instead of acarrier like Figure 1, which runs con-tinuously and is cut down from time totime, in accordance with the music,Figure 2, they use a zero carrier, andrather than cutting down, build it up,as determined by the audio wave. Thisis shown by Figure 6.

It will be observed that A and Bare still just the same as shown inFigure 2, also the radio frequency isspaced just as before, that is, it is stillthe same wave length, but instead ofhaving a continuous carrier, which islargely wasted, we have a zero carrier.At point C, where the singer has stopped

A

AfijoymniglIpa

Fig. 6. Carrier Suppressed

for an instant and the audio wavedropped to zero, observe that the radiofrequency has also been reduced tonothing, and the ether is undisturbed.

Detector Separates WavesWhen either of these waves, Figures

5 or 6 is fed to a detector, it skims theaudio wave off the back of the radio bysuppressing the lower half of the radiocurve, as already explained in our June1 issue, "Changing Radio to AudioWaves." But the latter has some ad-vantages. In the first place the tuningis somewhat sharper, since all the en-ergy is used, rather than a fraction ofit. Sharper tuning results in a clearertone for the music you want to hear, andalso in the more perfect cutting out ofinterfering stations. The second ad-vantage is that all the sending stationenergy goes into the waves, which arewanted instead of supplying a lot orunnecessary noise. From this it followsthat the sending range of the station isconsiderably increased.

If this new scheme of transmittingcan be worked out so that it is a com-mercial success without too much ap-paratus, it bids fair to become thestandard method of broadcasting.

BOARD OF TRADE LOSESWDAP

The Drake Hotel of Chicago, has re-cently taken over the management ofWDAP. This is the station which hasbeen run up until now by the ChicagoBoard of Trade. They have been put-ting such excellent concerts on the airthat we are sorry to hear of the change.However, Mr. Jack Nelson, who has beendirector, will still be retained, and thisprobably insures equally good programsin the future.

JULY 1, 1924 RADIO PROGRESS 7

Manted audio -frequency amplification. Infact, many throw together their audioamplifier parts of the circuit, afterspending much time and trouble in per-fecting the radio frequency and theaerial tuning circuits. No matter howsensitive and selective the latter may be,little satisfaction will be had if poorquality results from the neglect of theformer. Recently, however, there hasbeen a marked tendency towards the im-provement of audio -frequency amplifica-tion. This trend is shown by the in-creasing demand for the higher gradeaudio transformers in place of the poorlyconstructed and. designed units sellingfor a lower price.

As an engineering problem the lowerspeed of oscillation presents nearly asserious problems to be mastered as thehigher, but they are of a differentnature. In radio amplification we wantselectivity, but with audio frequency wedo not want selectivity since we wishto amplify equally over the entire audio -frequency band because voice currentsare composed of frequencies from 200 to2,000 oscillations per second, approxi-mately, while music ranges from 30cycles for the deep bass notes of anorgan to 5,000 cycles per second to theextreme high tones of a violin. Theproblem of keeping the oscillationtransformer from being selective andstill making it sensitive over the entireaudible range, which is 30 cycles to 5,000cycles, is indeed difficult and has beenmastered by only a few manufacturers.

Just as there is a marked tendencyfor a radio -frequency circuit to oscillate,there is a similar tendency for the audiocircuit to do it, too. Ofttinies thisvibration takes place at an audiblefrequency, that is below 10,000; it takesthe form of a howl. Then again, theoscillation takes place above the audio

A ew System of Audio AmplificationUse This in Your Two -StepAudio Frequency Receiver

By CHARLES H. M. WHITE, Consulting Engineer

ANY fans do not realize the good range, but it results in distortion. In oscillation. The result is that high qual-results to be obtained by well bal- other words, an audio -frequency circuit ity amplification is obtainable over the

has regenerative principles of feedback entire audio -frequency range without thewhich tend to make it selective, or more tendency towards howling or distortion.sensitive to one frequency than another. This arrangement also has the advan-

tage of cancelling out quite a bit of tubenoise in the same manner as push-pullamplification, and yet, for volume pertube as well as quality of received note,it is, in my opinion, superior.

Since the Twin-Aud is really nothingmore than two well designed audio-fre-

Many radio engineers have tried to curehowling by using a transformer of alower ratio in the second stage, but, per-sonally, I am not in strict accord withsuch practice, since the solution, to mymind lies in the transformer itself andnot in reducing the ratio for the later

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stages. The advantage of high ratiotransformers is the fact that they givemore amplification than those of lowerratio but their main disadvantage is thatthey are more selective and show a ten-dency to oscillate at a certain frequency,generally audible and so produce howl-ing and distortion.

Many radio engineers realized the ben-efits of high ratio and therefore setabout the task of curing its ills. Re-cently, the Peerless "Twin-Aud" bas beendeveloped. A Twin-Aud is two separateaudio -frequency transformers mountedon the same transformer core. Thereis a certain electrical reaction betweenthe magnetism of the two because ofthis style of mounting, which can beused to counteract any tendency towards

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quency transformers mounted togetherso that their magnetic fields exert acorrective effect unobtainable with twoseparately mounted transformers, thehookup is similar to those made withtwo of ordinary type. The arrangementhowever, makes it possible to as-semble the two stages more com-pactly than with the two separate units.As a matter of general practice it is wellto use a "C" battery if more than 45volts of "B" battery are employed. A"C" battery not only clarifies receptionbut also reduces the "B" battery currentwhich makes your batteries last muchlonger. The amount of "C" battery willdepend upon the amount of "B" batteryand the type of vacuum tubes used.

Continued on Page 8

8 RADIO PROGRESS JULY 1, 1924

Boosting the Wave LengthBy E. J. BUSSARD

When The Crosley Radio Corporation's the waveWLW Broadcasting Station began usingtheir new 423 meter wave, it was foundthat many owners of receiving sets didnot know how to adjust their radios totune in on the high wave length. It ap-pears that there are quite a number of

receiving sets on the market, manu-factured one to three years ago, whichwill tune to wave lengths no higher than400 meters. It can be readily seen thata radio of this nature is of no value forhearing programs between 400 and 600meters.

In the majority of cases, these re-ceivers are of the single circuit type. Itis easy to correct this type of set to re-ceive higher wave lengths. The mostcommon method is to insert a smallloading coil (explained below) in theantenna circuit. In quite a few cases,however, it is only necessary to increasethe length of the receiving antenna byadding, say 50 feet of wire. Anothercommon method is to remove the ad-justable condenser from the series con-nection with antenna circuit and placeit in parallel with the variocoupler coilof the receiver.

Making a Loading Coil

A few words of explanation of thevarious methods may be interesting. Bya loading coil is meant an inductancecoil; usually only a few turns of wireare necessary, placed in the antennalead, one side of the coil being connectedto the antenna lead-in and the other tothe aerial binding post. This method isespecially adapted to sets having only aninductance coil or variocoupler for tun-ing. To construct a loading coil, take atube three to three and a half inchesin diameter and wind it with 20 to 40turns of No. 24 or No- 26 gage D. C. C.(double cotton covered) wire. This tubeshould be of insulating material such asformica, hard rubber, etc., although card-board tubes are often used with success.The size of this coil will be determinedby the size of the inductance already inthe receiver. For instance, if the tunerwill receive stations broadcasting on 400meters at its highest setting, only 8 to12 turns of wire will be required to raise

length to 430 meters. How-ever, should 360 meters be the maxi-mum, then 20 to 25 turns would be re-quired. If there is only an inductancecoil in the receiver for tuning, then asmall fixed condenser of approximately.00025 Mfd. capacity, connected one ter-minal to the antenna binding post andthe other to the ground binding post,will be very satisfactory. If the circuitis tuned by a condenser used in serieswith a variocoupler, the wave lengthrange may be increased enough by con-necting it in parallel with the stator.

The Variometer SetA few complaints have been received

from people using three -circuit tuners.Undoubtedly the difficulty here lies inthe type of variometers used and it will,in the majority of cases, be necessary tosubstitute variometers having the propercharacteristics for tuning between 200and 600 meters. In a few cases, it maybe possible to wind a few turns of wireon the variometer and correct this de-fect to some extent, but the novice willfind no little difficulty in doing this.

KDKA'S NEW STUDIOWhen changes, now under way, are

made in the Pittsburgh Post studio ofthe world's pioneer broadcaster, KDKA,the famous Westinghouse station willhave a pickup studio perhaps better thananything of its kind in the world.

The new Pittsburgh Post studio isnow being installed in a separate operat-ing room, built-in to the main one, inwhich will be installed all apparatusnecessary for the operator to changeover microphones or make adjustmentsto the amplifying apparatus.

The new operating room is noise -proof and will have a two-way connec-tion with the transmitting station lo-cated in East Pittsburgh 14 miles away,so that changes made during the opera-tion of the station will be instantaneous.

Window for BoothIn this operating booth will be located

all the amplifying apparatus and thevarious switches which are usually seenin the ordinary studio. In order that theoperator can see what is going on, awindow has been built in the side of the

operating room. This window can beclosed when the station is working topermit conversation between the trans-mitting station operators without itsbeing broadcast.

This change is one of numerous onesthat have been made in the PittsburghPost pickup station of KDKA, its firstsince they began broadcasting fromdowntown Pittsburgh.

It is not generally known that EastPittsburgh, where the sending aerial islocated, is 14 miles east of Pittsburghand that most of KDKA's broadcastingis done from outside points, or pick-upstations as they are called. In broad-casting events from Pittsburgh and thesurrounding district KDKA uses 34pick-up points.

CAN YOU TALK ILO?

It is the Popular Radio LanguageThe Spanish and French lessons

taught by radio from the WLW Broad-casting studio of The Crosley RadioCorporation met with such hearty re-sponses from the listener -pupils, that anew language will be added in Septem-ber. Ilo, "La Internaciona Linguo,"will enable listeners in other countriesto enjoy more fully the numbers an-nounced from the Crosley station, forplans now being formulated will includethe studio director's announcements inseveral languages. In addition to theannouncements, students will be taughtthe Ilo language in the regular CrosleyRadio University classes. Fred Smith,who spent many years in Europe, isstudio director of the WLW station andwill supervise the classes.

NEW SYSTEM OF AUDIOContinued from Page 7

If any radio fans are interested in thefurther construction and characteristicsof this circuit as shown in the diagram,I shall be pleased to put them on theright path if they will only address mein care of Radio Progress enclosing aself-addressed envelope. If you are nowgetting imperfect audio -amplification youwill do well to give this new system atrial before you make changes in yourcircuit. A receiver is no better than itsaudio amplifier.

ti

4


Development Work Pushed by G. E.Latest Device Prevents Interfer-ence from Lighthouse Signals

NONE of the big radio companies aresatisfied with the present state

of the art, although every one will admitthat wonderful progress is being made.The thousands of experimenters who aretrying out new hook-ups all the timehave accomplished a great deal in de-veloping radio, but the time has comewhen more laboratory work is neededto make much further advance. For thismason a large experimental radio sta-tion will shortly be built by the GeneralElectric Company for a more completeinvestigation of radio phenomena andbroadcasting. It is understood that thecost of the experimental station will beapproximately $150,000, and that it willbe located on land recently acquired bythe company in Schenectady.

While no plans have been drawn forthe new station it is understood thatthe General Electric Company will builda power house capable of delivering, highpower at various frequencies, and an-tenna structures will be erected for a.

wide range of wave lengths so that sys-tematic investigation can be made ofthe advantages of various frequenciesin solving the many problems withwhich radio now has to deal.

Interferes with CodeAt present the ordinary wave length

used ranges from about 250 up to 550 me-ters for ordinary broadcasting. If eitherhigher or lower lengths are used, inter-ference is found from the code of ama-teurs or commercial ship stations. Butin addition to this band of frequenciesseveral of the big stations have beentied together by wave lengths of around100 meters. This is low enough so that itavoids trouble from the 150 to 200 meterband of the amateur practicing code. Bythe word "band" is meant all the dif-ferent speeds of vibration which givewave lengths within these limits. Thatis, it would take in frequencies from151, 152, 153, etc., up to 200 meters.

The requirements of the present-day

reports at noon, an afternoon concertfor those at home, evening stock andmarket quotations, weather reports,musical program's, plays and religiousservices, have filled up the availabletime. It has also been found that thespace available in the power house andoperating section of the big broadcastingstation is not sufficient to permit ex-perimental work without interferingwith the regular programs. On thisaccount a new station was considerednecessary for intensive experimentalwork.

2XI Equals WGYThe broadcasting station now known

the world over as WGY was originallybuilt, several years ago, for experimentalpurposes. Operating under the experi-mental license 2XI, it has conductedvarious radio experiments, and addedmaterially to the fund of availableknowledge.

Even now you will sometimes hearthe call 2XI late at night and sometimes the music will come through even

.101DASH Der Der

Fig. 1. Old Lighthouse Waves

better than from WGY, while again itmay be somewhat inferior. This isowing to the fact that new stunts areconstantly being tried, and if they seempromising are worked out at greaterlength in the laboratory. But suchexperiments take considerable time andlots of space for the set-up.

Two Wave Lengths TogetherIt is well known by advanced radio

fans and those familiar with the work-ings of this station that the regular pro-grams have been broadcast for manymonths at two wave lengths-the reg-ular one of 380 meters available

broadcasting program, including stock to those using standard receiving outfits

and also a lower wave length of 107meters which has been found particu-larly well adapted to long distancetransmission for re -broadcasting. Onseveral occasions during the early spring,WGY's programs have been re -broadcastby the British Broadcasting Company inLondon and thus made available to theBritish Isles as well as to France andother continental countries. This isonly one of the experimental develop-ments to which WGY has contributed.

Why You Don't Get 107The reason the average radio has not

been able to pick up this 107 meterwave is because the lowest wave lengthwhich most sets can get is around 250or 275 meters. In order to build over a setto receive this short wave length, whichruns at a much higher frequency orspeed of vibration, it is necessary toredesign the coils and condensers sothat they are considerably smaller thanwhat is used at present. Even whenthe variable condensers are turned sothat they read zero on the dial it mustbe 'remembered that there is still quitea bit of leakage capacity, even in thebest instruments. To this must beadded the leakage capacity 'betweenthe various wires in the set. When allthese facts are thought of it is not sur-prising that the ordinary radio can notbe made to oscillate at the tremendousfrequency of three million times a sec-ond, which is the equivalent of a 100 -

meter wave.

Blazing the TrailNo one believes that radio and radio

broadcasting will remain stationary. Theremarkable advances which have beenmade in the last few years indicate acontinued rapid development. The Gen-eral Electric Company aims to perfectbroadcasting so that it may becomeeven more reliable and satisfactory. Theservice which radio now renders to thefarmer and to all that large proportionof the population in outlying districts is

10 RADIO PROGRESS JULY 1, 19'24

invaluable, but it can be made an evengreater factor by further perfecting.

Light Ship RadioAn illustration of one of the de-

vices just put out from their laboratorywhich may be mentioned is an improvedsending apparatus for fog signals.

Marked improvement in the sendingof signals from lightships and light-houses has been achieved through thedevelopment by radio engineers of theGeneral Electric Company of a vacuumtube radio transmitter expressly de-signed for this sort of work. In testswhich have just been completed on

Lightship 108, at Staten Island, the newtube set showed superior efficiency ascompared with a typical spark set, ofthe type which has been used for a num-ber of years by the United States Bu-reau of Lighthouses.

The diagrams explain this action morefully. They show how the waves lookfor sending the letter D in code. D ismade by sending a dash and two dots.Figure 1 shows the wave form under theold scheme. It will be seen that dashconsists of several series of impulses,each one starting strong and then dyingaway. These individual impulses are

JlCAMDerFig. 2. Letter "D." New Style

is considerable longer. It is easy to seethat the second style of sending will bemuch more efficient than the first. Thereis the same difference between a lot ofjerks and a steady pull.

During the tests, both of the fog sig-nal radio transmitters were adjusted togive about ten amperes in the aerial. Itwas found that the total power con-sumed by the spark set averaged around2300 watts, which was nearly 50 percent. greater than the power consump-tion of the tube set, the latter beingabout 1650 watts.

Saves 26 Bulbs BurningThe watts are a measure of the power

used, or expressed in another way, ofthe fuel consumed per hour in runningthe station. One of the most popularsize of incandescent lamps which youuse for lighting your kitchen is the 25 -watt bulb. In cutting the power as justmentioned, there is a saving of 650 wattswhich would keep 26 ordinary electriclights burning continuously. This, yousee, is quite a worth while result.

This will have a direct bearing onthe question of fuel supply to light-ships and lighthouses, since the powerfor these sets is supplied by gas enginedriven generators, in which kerosene isusually burned. If the lightship orlighthouse is in an inaccessible location,as is often the ease, a considerable sav-ing in fuel and other expenses can be

caused by the spark breaking across the effected if fuel ships are not required tospark gap. Each time a spark occurs, a make the trip as frequently as at pres-train of waves is sent out. Of course, ent.this wave train gradually fades out, be- The tube set was shown to be safercause of the resistance in the circuit. Itis very much like a piano. When apiano key is struck the note starts quiteloud and then gradually dies away. Ifthe same note is struck in rapid suc-cession, then the tone will be sustained,but the ear will be able to catch the dif-ferent individual impulses and a pictureof the note will look just like Figure LThe dots are made in the same way asthe dashes, except they are not pro-longed for the same length of time.

Does Not Waste EnergyFigure 2 shows the new scheme of

sending out the waves. Here the tubeset gives an oscillation which does notdie down at all. This is known as asustained wave. Here again the dashand dot are alike except that the dash

lo operate and much more simple thanthe spark sets heretofore in use. Theefficiency of the set is due to the useof the latest type of sending tube, calledthe XL.

Won't Knock Out MusicThis set, the development of which

has now been completed by the GeneralElectric Company, was particularly wel-comed because of its non-interferencecharacteristics. The spark sets hereto-fore used have been the cause of manycomplaints from listeners to broadcast-ing stations, who have' been annoyed byinterference originating with these sets.This condition will be remedied by theuse of the tube sets.

This is because the new sets send outa very smooth wave at an exact and

unvarying wave length, and only radiostuned to this particular speed will pickthem up. The older sets were adjustedto give this same length, as closely aspossible, but they did not send out apure wave. Various harmonics or higherfrequencies (shorter wave lengths) wereradiated at the same time and it wasthese extra and unwanted vibrationswhich caused all the trouble to neighbor-ing broadcast listeners.

Lighthouse Bureau TestsThe outcome of the tests with the

new set was a recommendation by Super-intendent of Lighthouses of the ThirdDistrict, J. T. Yates, to the Bureau ofLighthouses in Washington, that thesetube sets 'be generally adopted for thebureau's radio beacon stations.

The radio signals sent out during foghave played no small part in the safeguiding of vessels and the saving of life.The signals are transmitted at 1000

meters in combinations of dots anddashes which enable pilots of vesselswithin range to determine, from thecombination, what station is sendingand its direction from the ship. Eachstation sends in regular repetition.

Got Your License?The American Telephone and Tele-

gra,ph Company stated recently thatmore than forty broadcasting stationsthroughout the United States that wereformally infringing their patents badtaken licenses. Inquiries in regard tolicenses and applications for licenses arebeing received in considerable numbers.Permits under the patents of the Ameri-can Telephone and 'Telegraph Companyare being granted to broadcasting sta-tions now infringing under conditionswhich have been generally accepted asfair and reasonable.

PRIZES FORSUBSCRIPTIONS

Head Phonesor

TransformersFREE if you sec-re two subscriptionsfor RADIO PROGRESS for oneyear- your own and that of a friend.

JULY 1, 1924. RADIO PROGRESS 11

Regeneration and ReflexHook-up of Trirdyn ShowsAn Unusual Combination

HERE has been considerable in-

quiry recently about the Trirdynset. This word (pronounced Try -Are -Dine) is made up of the numerals 3R3,combined with the popular ending

"idyn," which comes from the Greek

word meaning powerful. These threeR's stand for regeneration, reflex andradio frequency.

What the Three R's MeanIn this connection it might be well

to explain the meaning of these threeterms. Regeneration is used in the

same sense as with the ordinary set.

This signifies that there is a ticklercoil connected in series with the plateor output circuit, which feeds energy

in the customarymanner. This is the same action, whichis the subject of the patent litigation be-tween Major Armstrong and DeForest,which, up until recently, has been calledthe Armstrong Patent, but has only justbeen awarded by the courts to Lee De -Forest.

Radio frequency amplification is madeuse of in the first tube. This increasesthe volume of the incoming carrierwave and so extends the range con-siderably. The reflex action takes placeby using this same first tube, whichalready has been used as a radio ampli-fier, in the further capacity of an audiofrequency amplifier. It is in thismanner that we get the three R's re-ferred to above.

Use of the Third TubeSo far we have employed only two

tubes. The waves coming in throughthe first are amplified and passed to thesecond as a detector. From there theyare looped back through the first again,rad amplified at audio frequency, thusincreasing the loudness of the signal, aswell as the range. The jack, which ap-pears on the front of the panel is con-nected at this point, and when phones

re inserted, only these two tubes areconnected, but if it is desired to use aloud speaker, then the phone plug is

withdrawn and this connects in thethird tube, which acts as a second stepof audio. This makes the music loudenough to be heard on any loud speaker.

Figure 1 shows the appearance of thisset with the cover closed. The numeralsin circles referring to the different partsare the same throughout all the dia-grams. Aside from the two rheostats,Nos. 4 and 5, the panel has only threecontrols. Dials 1 and 2 adjust the

Fig. 1. Outside

capacity of the grid circuits of the radioamplifier and the detector. This is whatfurnishes the sharp tuning of the set.Handle 3 controls the amount of feed-back. But instead of turning it, it is

pushed in and pulled out in the usual'Grosley manner. When it is pulled outit brings the movable coil (connectedin the plate circuit) up close to thestationery coil (detector grid circuit).This gives close coupling and a largeamount of feedback. Pushing on theknob, thus separating the coils, producesthe action between them, and so cutsdown on the regeneration. With aver-age operating conditions the normal

position of the handle is about one-halfway out.

Figure 2 shows a rear view of thepanel. Of course, the set is turned theother way around so that the right handside of the set viewed from the front isnow shown at the left. An explanationof the figures shows:

1-This is the variable condenser, tun-ing the grid circuit of the radio ampli-fier.

2-The same thing in the detector cir-cuit.

3-Is the movable coil governing the

10

View cf Trirdyn

feedback. It corresponds to rotor of avariocoupler, and is adjustable by push-ing in and out.

4-The rheostat controlling the fila-ment current of both radio and audioamplifiers.

5-The same for the detector.6-First stage audio transformer.7-Second stage ditto.8-Antenna coupler. This consists of

a primary in series with an aerial anda secondary connected to the grid.

9-The radio frequency transformer.It is also the stator of the variocouplerfor introducing regeneration to the de-tector. Primary and secondary coils are

12 11.1. DIO PROGRESS JULY 1, 19:24

both wound on this stator in regularspider web construction.

10-Phone jack for use with first audiostep only.

11-By-pass or stopping condenser indetector plate circuit.

12-Main switch for shutting off en-tire set.

Hook-up is ShownFigure 3 shows a simplified hook-up

of the set, leaving out the filament con-nections, which are standard. Figure 4shows the same hook-up in the pictorialstyle. The way the circuit works is

this. The radio waves come from theaerial to the adjustable loading coil L

<90.40000000,000.000

Fig. 2. Various Parts Shown from Rear

13-First tube, both radio and audioamplifier.

14-Second tube detector.15-Third tube. Second stage of

audio amplification.16-Grid condenser .00025 nifd. and

grid leak 1 to 4 megohms dependingon tube used for detector.

17-"B" plus terminal for detector.18-Aerial connection, giving sharp

tuning.19-Aerial connection, giving louder

results, but not sharp as 18.20-"A" plus battery terminal.21-"B" minus battery terminal.22-Ground.23-"A" minus battery terminal.24-"C" minus battery terminal "C"

battery is not needed if only 45 volts of"B" battery are used on the amplifiers.In that case, posts 23 and 24 are to beconnected together by a short piece ofwire, but where a higher voltage is usedon the amplifiers, then it is desirable toconnect a "C" battery. Its voltageshould depend upon the amount of "B"battery used in accordance with thetable on the direction sheets, which ac-companies every amplifier tube.

25-"B" plus battery 45 to 90 volts.26-Loud speaker terminals.

22+)

hocn in the upper left hand corner offigure 4. This coil is actually mountedon the inside wall of the cabinet.

This loading coil is used only to com-pensate for different lengths of aerial.With a short one, 25 feet or so, the en -

4 -

one of these two terminals. These arethe leads of the primary coil. No. 18has only a few turns, and so gives veryloose coupling, resulting in sharp tuning.No. 19 has more turns, and so thetighter coupling gives less selectivity,but increased volume. The secondary ofthis coil, wound on the same spider web,runs to the grid of the first tube. It istuned by condenser 1.

Output to TransformerThe output from the plate runs

through primary of radio transformerR, back through condenser C to the fila-ment. The secondary of this transformerruns through grid condenser and leak tothe grid of the detector tube. It is

tuned by variable condenser 2. The platecircuit of the detector passes throughthe adjustable tickler 3, and then theprimary of the first audio transformer,Al.

The secondary of the audio trans-former impresses the audio frequency.on the grid by running through the sec-ondary of coil 18. Since this lat-ter is a radio frequency coil, and has onlya few turns, it does not affect audio fre-quency at all. The audio output from theplate after going through the primary ofradio transformer R, (which again doesnot affect it, owing to its few turns),reaches the jack. If the phones are

B2..+Fig. 3. Hookup. Numbers a,s in Fig 2

tire coil is used. A 100 -foot antenna willneed not more than the first tap in se-ries, and if it is as long as 150 feet, thenthe entire loading coil is disconnectedand out of use. The other terminal ofcoil L is connected to binding post Alor A2, or, as just mentioned, with a longaerial the lead-in is connected direct to

FLOUD

SPEAKER

Aa

plugged in, the signals are heard withone radio and one audio amplification,as just described. But if the phone plugis pulled out of the jack, then the pri-mary of audio transformer A2 is in-serted in series. The secondary of A2goes to the grid of the third tube and

Continued on Page 13.

CLIC 1, 1924 RADIO PROGRESS

Common Sense in Seven Chapters1. Night Range Versus Day RangeThe night ranges of sending and re-

ceiving stations is much greater thanthe day range. Do not expect tohear stations a great distance away inthe daytime. There are nights, rare inwinter, and common in the summer,when it is impossible to bring in dis-tant stations. This is due to atmosphericconditions beyond human control. Thiscondition should be met philosophicallyas something that cannot be avoided,and not used as the basis of a complaintto the radio dealer who sold you yourset.

2. Batteries Are the FuelA radio set will not work satisfac-

torily when the batteries are run downor nearly so. Keep your storage batterywell charged, or if you use dry cells, al-ways use some that are in good condi-tion. Test your B batteries with a volt-meter occasionally and renew them whenthe voltage is 1/3 below normal. This is15 on 22 volt block or 30 on a 45 block.

3. Watch the DetailsDon't talk about the wonders and

mysteries of radio, and the scientific anddelicate sets that have made it possible,and then condemn the dealer or manu-

facturer when your set won't work withthe aerial disconnected, the vacuumtubes burned out, or the batteries con-nected with the wrong polarity. A sci-entific instrument, even so popular a oneas a radio set, must be treated in an in-telligent manner.

4. Learn the Art of TuningIf you have not learned to tune prop-

erly, but manage to tune in one longdistance station, don't condemn your setbecause you do not hear them all. Thefact that you heard one distant stationshows that the set is all right; all youneed is patience and practice, and youwill be able to get the same far awaystations as your neighbors.5. Brighter Tubes Means Less Life

Don't expect to get louder or clearermusic when your vacuum tubes areturned up brighter than normal. Ifanything, the reception you receive willbe less loud and there will be unpleasantnoises introduced. Remember, also, thata slight overload on the tubes will makethem burn out in a fraction of theirnormal life.

6. Don't Miss To -day's PrograxnRadio does not change overnight any

13

more than doe, the automobile, thephonograph or the sewing machine. Theset that you buy to -day will be good ayear from to -day, and probably for manymore years. The long-distance receivingsets in thousands of homes at presentare practically identical, except for somerefinements, with the sets that were usedby radio -telegraph enthusiasts five yearsago. If you have postponed getting agood set because you are waitingfor a radical change in radio, you aremissing more enjoyment than the indi-vidual who puts off buying an automo-bile for the same reason.

7. Lightning Protection SimpleWith a loop or an indoor aerial there

is of course no need for antenna protec-tors. In the case of the outdoor aerial,the condition is somewhat different.During a storm the aerial may pick upsome static electricity, which should beprovided with an easy path to theground, in order to protect the receivinginstruments. The danger is not that theaerial will be struck, but that the staticcharges are likely to overload your re-ceiver if not provided for by an ap-proved lightning arrester.

attki-YTRIRDYN

3R3

DW. 0,1V1

Fig. 4. Pictorial Hookup of Trirdyn

REGENERATION AND REFLEXContinued from Page 12.

the output from the plate runs throughthe loud speaker in the usual manner.

Advantages of the TrirdynIt will be seen that this set will not

radiate and cause trouble to the neigh-bors, even though it employs a feedbackcontrol. If this regeneration is turnedtoo high so that the detector oscillates,it will not squeal into the air as manyother receivers do, since the radio fre-quency tube is inserted between it andthe detector. This tube does not oscil-late. Furthermore, the loose couplingbetween the primary and secondary of8, the antenna coupler, would stop anyradiation originating in the set fromgetting out into the air.

Another advantage is the sharpness oftuning. It has been found that two sta-tions differing by only a few meters inwave lengths can easily be separated.Any kind of tubes can be used, butUV -200 and 201-A are usually recom-mended for this outfit.

RADIO PROGRESS JULY 1, 1924

Picture of a Popular Performer

Mr. Edwin F. Goldman

THEIR DANCE MUSIC IS GOODMr. Edwin F. Goldman, is shown here.

He is the conductor of the famous Gold-man Band. Indeed, it was his abilitywhich founded and has kept up this wellknown group of musicians. WJY, NewYork, (405 meters) are fortunate to be.able to broadcast such good music asthis aggregation of players is producing.If you want some good, lively dance

music, tune into them some evening;and you will be delighted.

The programs, arranged and directedby Edwin Franko Goldman, are noted asbeing the most unique and most ambi-tious band concert programs attemptedby any organization in the country, andthe fact that the Goldman Band is theonly organization to have given sevenconsecutive New York seasons is proofenough of the exceptional success of theattempts.

PUTTING MADISON SQUAREON THE AIR

In bringing signals of adequate volumefrom the Democratic National Conven-tion at Madison Square Garden, NewYork, to the antenna of WGY, at Sche-nectady, N. Y., the sound energy pickedup by the microphones in New York wasamplified at six different points on thejourney.

As the voice or sound was picked upby the microphones in Madison SquareGarden and converted into electrical vi-brations, an amplifying unit built upthe energy to counteract the loss sus-tained in transmission over wires to -thestudio of WJZ at Aeolian Hall on 42ndstreet, New York. At the control roomof WJZ the signal was amplified forfeeding to the air and part of the ener-gy, normally sent to the station was di-verted by wire to the Walker StreetTerminal of the Western Union. Herethe signal was boosted or amplified forthe third time and sped on its waySchenectady -ward. At Sedgwick ave-nue, where the control wire leaves theNew York city cable and goes into anopen wire, strung on poles, a fourth am-plification took place. This fourth stagegave the signal sufficient strength toreach the control room of WGY in Sche-nectady. There a fifth stage of amplifi-cation was applied to the message toovercome line loss over the quarter -mileof wire between the control room andpower station. The last power amplifi-cation took place at the power stationand the signal was then impressed onthe radio apparatus and given to thelistening fans tuned in on 380 meters.The journey of an electrical vibrationfrom Madison Square Garden to the eartuned in to WGY is made with the speedof light.

To assure good service to its follow-ers WGY had nine operators along thecircuit. The men were apportioned asfollows: At Madison Square Garden, oneman; WJZ control room, one man;Walker Street terminal, one man; Sedge -wick avenue, two men; WGY controlroom, two operators; WGY power sta-tion, two men.


Unradiating the Single CircuitThis Will Also Increase theSelectivity of Your Receiver

THE single -circuit regenerative re-

ceiver is probably more used in theUnited States to -day than all other cir-cuits combined. Among the obvious rea-sons for its popularity are its simplecontrols, low cost, and good results forsmall investment. It is the radio "Ford."But the single circuit is losing its popu-larity in favor of more expensive and

By HARRY A. NICKERSONelaborate sets for two reasons :-it isnot sufficiently selective, and it radiateswhen improperly operated.

Because of its many good features, itis unfortunate that it should be the tar-get for so much abuse. When the ownerof the expensive set begins to comparehis "stations heard" and "distance" rec-ords, he often finds his single -circuitneighbor has him badly beaten.

Mr. William Van Hoogstraten

Ten Feet of Wire Does ItThis article is not intended to de-

scribe a "cure-all" for the two great de-fects of the single -circuit, but it doestell how, by the mere addition of tenfeet or so of wire, the single circuit willgain marked selectivity and give less of-fence as a re -radiator. The idea may beadapted to other forms of single -circuitthan that most commonly used, but thedirections apply specifically to the single -circuit described as "a variocoupler set,using the tickler coil for producing re-generation" or as "the standard single -circuit regenerative set" or, sometimes.as "the Armstrong hook-up."

Fig. 1 illustrates the "standardsingle -circuit;" "S" is the stator of thevariocoupler, which usually has from 60to 80 turns of No. 22 or No. 23 wire."R" is the rotor of the coupler. Thearrow T pointing toward the stator isthe tap switch; the dots representfour switch points or taps on the stator.If taps are taken from the coil to twosets of switch points, it is suggestedthat the set which is fine tapped (onlyone turn per tap) be eliminated and thetaps used be four at most, connected asshown in the figure. It has been foundthat two or three taps in the standardsingle -circuit will give all the fineness ofcontrol desired, since the condenser isused for the fine tuning.

Note that the grid return is connectedto the "A" Battery Plus, not to "A"Minus. This connection is recommended

Continued on Page 16

PHILHARMONIC ORCHESTRAThe New York Philharmonic Orchestra

is one of the most popular musical organizations in the East. Our photograph

shows William Van Hoogstraten, its

conductor. Radio fans, who tune to 455

meters, will be able to pick up the

Stadium Concerts of this orchestra fromstation WJZ three times a week.


with all detector tubes, although the re-turn to Minus "A" is better with ampli-fier tubes. The "A" Plus connection isstandard practice nowadays for detec-tors.

High and Low DivideIn operation, the radio frequency

comes in from the aerial through con-denser C, which is adjusted for fine tun-ing, then through coil S, and out the tapswitch T, which gives coarse tuning, toground. The secondary, or grid circuit,is hooked up to the grid, through gridcondenser and leak and to coil S, throughtap switch T to the filament. The out-put starts at plate T, then to the rotorR of the variocoupler to the point X,where the radio and audio frequencydivide. The radio, or high frequency,goes through the by-pass condenser Oband back to the filament, but the low oraudio frequency goes from X throughthe phones and B battery to the filament.

Fig. 2 shows the same single circuitwith the changes made for its improve-ment. It has become a set with an un-tuned primary P, which is inductivelycoupled to the secondary formed bystator of the variocoupler.

is connected across the original couplerstator winding. No changes are madein the grid condenser or in the ticklerconnections, or in the battery hook-up.The real change is in the winding of theuntuned primary outside the usualstator coil. The correct position of thiswinding and the number of turns in itare both a matter of experiment, butvery excellent results may be had with-out the necessity for experimenting, pro-viding the general directions given arefollowed.

Primary Not TunedThe action in this case is asfollows:

The radio waves come down the aerialthrough coil P to ground. This primarydoes not need to have an adjustable tun-er, as it will respond to all wavelengths. The secondary coil S, which isthe stator of the variocoupler, is con-

nected to the grid through the grid leakand condenser as before. The other endof the secondary runs to ground throughthe tap switch T, which gives coarse tun-ing. Fine tuning is accomplished by theadjustable condenser C, which you willnotice is in parallel with the secondary.

&Ill 0 RE.TuRryGROUND

Fig. 1. Typical Single Circuit Radio

By "inductively coupled" is meant theaction which occurs when two coils arespaced close together and one of themcarries an alternating current. In sucha case, a corresponding voltage is in-duced or generated in the other coil.

Such a set has a good reputation, notonly for selectivity, but because it re -radiates but little. The variable con-denser is removed from the aerial, and

The operation of the output circuit isjust the same as before.

First, as to the exact number of turnsin this outer or "untuned" circuit. Ifwound directly over the original statorwinding, where selectivity is desired es-pecially, the number may be reduced toas low as three. This works well witha long antenna, say 150 feet, and shortwave lengths, below 400 meters.

For short antennas, the number maybe from 4 to as many as 15, but notmore than ten seems to give better re-sults than the larger number. The num-ber 7 was selected, as it seemed to aver-age best in tests made by the writer.

While this is not shown in the dia-gram, it is evident that if desired, theouter coil might be tapped, say at 2, 4,7, 10 and 15 turns, so that trial mightbe had of the various numbers to seewhich would give the best results. Ifthe original single circuit has two switchlevers with their separate sets of switchpoints, use could be made of the pointsconnected to the fine taps, by discon-necting these from the stator coil andusing them on the outer coil winding,to vary it. In this case, the switchlever used with the fine taps would beconnected to the ground.

Use of Sealing WaxThis outer winding should be of double

cotton or silk covered wire, of gauge No.18 to No. 24. The writer used No. 22D. S. C. (double silk covered). If thereis any doubt as to the quality of the in-sulation, a strip of paper may be woundon the stator and the outer windingwound over this. If care is used, a dropof sealing wax will hold the ends of theouter coil firmly enough in place, or col-lodion may be used as a binder, plus thedrop of wax.

The length of wire necessary to windthe outer coil may be computed byfiguring each full turn to be 3 1/7 timesthe diameter, plus a foot or two extrafor connections.

To avoid undesirable hand -capacity,the rotor of the condenser must be con-nected to the ground as shown. This isabsolutely essential. The condensershould be shielded with a strip of copperor tinfoil on the back of the panel. Thisalso is grounded.

The winding of the 7 -turn coil must becarefully done. The 7 turns may bewound closely together or spaced. Theymay be placed at either end of the statoror in the middle, or be wound so as tocover the whole length of the stator,spaced.

Winding the PrimaryIf the coupler stator is wound half on

one end of the tube and half on the otherend with shaft between, and consists of80 or more turns, it is suggested thatby all means, the 7 turns be wound just


above the middle of the stator winding metres is reached with maximum settingon the half of the stator coil that is con-nected tc the grid of the tube, at its endaway from the middle of the winding. If,on the other hand, the stator winding iscontinuous, the 7 -turn outer windingmay best be wound at the end of thestator winding, or near its middle,toward the "filament" end of the statorwinding rather than toward the "grid"end.

Care should be taken that the 7 -turncoil be wound over some part of thestator that is sure to be used when tun-

AR/.41-

of the variable condenser.It will probably be found that 45 to

65 turns of the stator coil may be usedwith a 23 -plate variable condenser inshunt with it, to cover nicely the broad-cast band of wave -lengths. The numberof turns used will, of course, depend onthe closeness of winding of the turns andthe diameter of the stator winding form.If an 11 or 13 -plate condenser is used,probably at least 65 turns will be neededto reach 550 metres.

Do not expect to hear distant stations

C b

RoroR

GvIc RP2Turify.CrRoUIVO

Fig. 2. Squeals Have Been Extracted from Fig. 1.

ing. For example, if it were wound onthe lower half of the stator in Fig.then when the switch lever was set onthe highest tap, the 7 turns would per-haps be too far away from the statorcoil in use to give the necessary energytransfer required for proper operation ofthe set.

In case it is found that the variablecondenser "C" will not tune down to,say, 250 metres, without setting thevariable condenser "C" at practically itsminimum capacity, it will be found thattuning will be improved by taking offanother tap in the stator coil, so a lessnumber of its turns may be used.

If, on the other hand, when using thehighest number of turns of the stator,it is found that considerably higher than550 metres is reached, a part of the endof the stator coil winding (not from thegrid end of the stator, of course) shouldbe removed until a little more than 550

2,

kr)

z

0.

with this changed single -circuit unlessthe tickler connections, in the originalcircuit are so made that regeneration isobtainable over the broadcast band. Ifthe set refuses to make a rushing orclicking (sometimes a violent squawk) inthe phones when the tickler dial ismoved through its circle of revolution,the leads to the tickler (rotor) shouldbe reversed. If regeneration is still lack-ing, a larger phone condenser, a newtube, an antenna -ground system withlower resistance, higher filament current,a higher or lower "B" voltage or newB battery, change in value of grid -leak.a new grid condenser, or the attentionof some radio expert, may be requiredto remedy the lack of regeneration. Aregenerative set that won't regeneratewon't give better results if the changessuggested in this article are made. Buta good single -circuit may be improvedin 'selectivity and in lessened tendencyto re -radiate when improperly operatedby making the hook-up that of Fig. 2.

WHICH WOULD YOU DO?A thorough plan to adapt radio to the

public school is now being tried out bythe research director of the Oakland,Cal., public schools with the help ofKGO, the Pacific Coast station of theGeneral Electric Company. Tests al-ready made show the boys and girls likeschool a lot better since the radio hasbeen put in.

Dr. Virgil Dickson, research directorof the Oakland schools, reports that thecommittee working on this problem isdivided into two groups which do notagree. One believes that a lesson byradio should be limited to a subject ofspecial importance, broadcasting a goodspeaker who knows more about it thananybody else. This is the lecture typeof lesson and will be limited to special-ists.

Group two thinks that radio should bea means for giving actual classroomlessons. They believe that radio maytake the place of the classroom teacherand give the same kind of lesson; how-ever, the regular teacher will listen in.and point out upon maps, globes orcharts, the topics referred to by theradio instructor. The classroom teacherwill also direct operations of the classand see that pupils make proper notes.

The lecture plan of group one has al-ready been tried out by broadcasting onelesson in music and another on Indiancustoms. Reports from various schoolslistening in prove that both lesons weresuccessful. Opinions of group two havenot yet been proved, as the test lessonson geography, Shakespeare, and commer-cial arithmetic have not yet been fullyreported. Under both systems the radio'teacher was helped by some of her pu-pils speaking into the microphone. Thismade it seem real to the class.

The attention of the children was heldby musical numbers. Plans for theShakespeare lesson included musicplayed for five minutes at the beginning,again in the middle and once more atthe end of the talk. By this means theminds of the students and teachers werefreshened for the attention necessary toarasp the main points in the talk. Thefive minutes of music in the middle of thelesson let slower pupils catch up withtheir note taking. At the end of thelesson the five minutes of music seemedto rest the entire class and put them insmiling humor 'before dismissal.


Some Sending Station StoriesHENRY FORD ON THE RACES

Most of the thirteen million automo-bile owners are interested in the Inter-national 500 -Mile Race at Indianapolis,yet only about one hundred and fiftythousand of them get an opportunity tosee it. But this year, The Prest-O-LiteCompany, whose enormous factory is di-rectly across the road from the Speed-way, broadcast the race through the Chi-cago Tribune Station, WGN, and thespeed fans got a realistic impression ofthe race on their radio. A special wirewas run from a soundproof booth infront of the judge's stand at the Speed-way direct to the broadcasting stationat Chicago.

Arrangements were made to covereverything that was doing at the huge2% -mile brick oval. Telephone linesfrom all important points at the trackled to the sending booth. For instance,experts stationed at the pits told thestory of the pit stops of the cars. Re-porting the standing and the speeds ofthe cars was a job requiring quick think-ing, as the race proved to be the fastestand most bitterly fought in the historyof the classic. Now one driver wasahead, then another.

The broadcasting was very realistic.The roar of the motors, the cheering ofthe crowds, the quick commands of thedrivers as they stopped for supplies andhasty adjustments were so graphicallytransmitted from the pits that listenerssaid. "Everything was there except thesmell of burning rubber." Henry Fordsupplied an unexpected feature by ad-dressing the radio fans on the signifi-cance of the race in relation to the auto-mobile industry. Mr. Ford, who him-self was a builder and pilot of racingcars in the early days of his career, wasreferee of the race.

It is reported that the broadcastingaroused unusual interest. Hundreds ofthousands of sets tuned in and in radiostores, garages and private homes greatcrowds followed the progress of the raceon special charts. Thousands of tele-Pra MS, letters, and applause cards werereceived thanking The Prest-O-Lite Com-pany and the Chicago Tribune for thewonderful program, and congratulatingthem on their success.

ARE YOU A FOREIGNER?Victor Saudek, conductor of the KDKA

Little Symphony Orchestra, is arrang-ing a series of international radio con-certs and musical programs which willbe broadcast from Station KDKA. Aschedule is being prepared in which oneevening will be devoted to each nation,and the concert will be broadcast in thelanguage of that nation as well as inthe English language. Although KDKAhas already broadcast several programsin Spanish for the South American aneLatin countries and other broadcastingstations have transmitted concerts inforeign tongues, this is the first timethat a complete series of internationalconcerts have been arranged. Mr. Saudekis also endeavoring to secure the consulsof the various nations to deliver the welcoming address. The national "dish" ofthe nation whose concert is being broad-cast, which will be served with the re-freshments for the broadcasting artists.will also be an additional feature.

CANOEING BY RADIOHow bmeficial and valuable from ad-

vertising purposes a radio broadcastingstation can be to a municipality was re-cently beautifully illustrated in Spring-field. Mass., in connection with a ship-ment of canoes from Old Town. Me..to a Springfield hardware establishment.The shipping tag bore the name of thehardware store and nothing else but theinseription, "Springfield. the home ofWBZ." With the number of cities andtowns throughout the States with thename Springfield, mail clerks might haveexperienced some difficulty in locatingthe consignee. But the additional ma-terial on the tag referring to the Spring-eld Westinghouse radio station left little

doubt as to where the canoes were going.

HAND ORGANS NOT INCLUDEDA curious fact has been noted by

Station WBZ in comments from radiolisteners regarding organ broadcasts.Very few persons,, prior to radio, everheard an organ other than in a churchor a "movie," and the idea of an or -(ran studio is novel to them. Through

the courtesy of WBZ, fans have

been able to compare two organs,the one in the Steinert Studio wherethe Aeolian organ is played andthe one in the Estey Studio bearingthat name.

ANNOUNCED IN THREELANGUAGES

Fans who receive broadcasts fromCanada's premier radio station CKAC,are familiar with the fact that all an-nouncements have been made in Frenchand English.

Soon, a third language will be added:"La Internaciona Linguo"-ILO, theperfect radio auxiliary internationallanguage-simple, neutral, expressiveand logical.

Jacques N. Cartier, director, and hisstaff of announcers and story -tellers, arestudying Ilo, and find it extremely easyto learn.

By the time the new big plant ofCKAC has been installed, everybody con-nected with the studio expects to be ableto talk Ilo, and then this musical"tongue" will be on the air regularly.

Heretofore, CKAC has found twolanguages enough for its needs, but nowthat constantly increasing numbers ofradio enthusiasts are clamoring for Ilo-"Well, not to advance is to recede," ac-cording to J. N. C., "and in Ilo all fanshave a new standard! There is no otherway possible for us to satisfy everybody.All non-English and French fans, withinour range, advocate Ho."

Mr. Cartier points out that CKACserves a big Italian colony, a Greek vil-lage, a miniature Vaterland, a tinyChinese town, a large Jewish settlementand several other small colonies.

"SLEEPING SICKNESS"A radio fan in Charlottesville, Vir-

ginia, writes that the only trouble withthe Westinghouse Station KDKA is thatthe directors in charge of the stationhave sleeping sickness. The concertsare received very clearly and distinctlyand are enjoyed regularly each eveningaccording to the letter, but this listenerrequests that "KDKA stay up a fewhours later in the evening."

JULY 1, 1924 RADIO PROGRESS

Saving the Storage Battery'sDon't Commit First DegreeMurder on Your Battery

THE storage battery is the most im-portant piece of apparatus used in

radiophone receiving sets to light thevacuum tube filaments, and sometimesto operate the plate circuits; it is oftencalled the heart of radio set equipment.Good signal reception depends to a largeextent upon the care which the batteriesreceive so as to avoid getting hissing,frying and scratching noises (which areoften blamed upon static electricity)along with the signals.

Many persons have an idea that elec-tricity is actually stored in these de-vices, just the same as if a lot of appleswere put away for winter use in a basket.As a matter of fact, it is the energy ofelectricity that is put into the cell, andwithdrawn later with a limited loss.What occurs is, that the energy of thecharging current changes the chemicalsin both positive and negative sets ofplates into a different chemical form.After the charging current is cut off, thebattery is connected to the radio outfit;when its circuit is closed, these chemi-cals are changed back to their originalform, and in doing so, generate electricalenergy.

Acid and Alkaline CellsThere are two types of storage bat-

teries on the market: the first consistsof specially prepared lead plates stand-ing in a solution of sulphuric acid andwater. The other is known as the Edi-son battery; its plates are made ofnickel steel, and contain nickel peroxideand spongy iron immersed in a solutionof caustic potash. Both kinds have theiradvantages and disadvantages, therebeing no perfect storage cells made.Storage battery capacities are rated bytheir manufacturers in ampere -hours.Thus a 60 -ampere hour cell will supply6 amperes of current for 10 hours, 3 am-peres for 20 hours, or 1 ampere for 60hours. That is, the current times thehours equals 60. But it would ruin astorage battery to take 60 amperes outof it in one hour's time; the

By W. S. STANDIF ORD

plates would buckle under such arapid discharge rate. Batteries inradio service, as contrasted with thoseused for automobile lig.hting and self-starting, operate at extremely low dis-charge rates, one, two, or three amperesbeing about an average current; it de-pends upon the number and kind oftubes used.

Radio vs. Auto BatteriesConditions of battery working in the

automotive and radio fields differ con-siderably; the radio field demands asteady current discharge without fre-quent recharging, while the automobileoutfit is constantly being recharged withthe result that the current consumptionis at a minimum. As storage batterieshave, before the advent of radio sets,been used mainly in intermittent Work,their ratings in ampere -hours is basedon this method of operation and will notbe exactly true in continuous use. Inpurchasing and using storage batteries,the above facts should be kept in mind,and cells bought which have a large am-pere hour rating. The radio noviceshould realize, that while a 40 amperehour battery costs less than one of 120ampere hours, the former will become ex-hausted in one-third of the time of thelarger one, thus making it necessary tobother with frequent recharging, whichcosts money and loss of time.

When Is It Charged?For the benefit of those amateurs who

have a recharging outfit and are unableto tell when a storage cell is fully re-charged, the following pointers will beof interest. The completion of chargingis known by several signs. The colorsof both plates are fully restored, thepositive being a rich dark chocolatebrown and the negative a light grayishblue color. The density of the acid isbrought back to its highest value, 1.275to 1.300. The pressure is over two voltsand in some cases may be 2.5 at the endof a recharging period. Copious streams

Life

of gas bubbles are given off from bothplates; oxygen at the positive and hydro-gen at the negative. These bubbles appearat first in small quantities, but they in-crease more plentifully as the plates arecompletely charged. The acid and watermixture at this stage looks quite milky.

STEM MARKEDIN FIGURES

EMPTY

HALF

FULL

_LEVEL OFELECTROLYTE.

FL0AT

CHAMBER

WEIGHT FILLEDWITH LEAD SHOT

Fig. 1. Battery Hydrometer

When nearing completion of the charge,a fine spray is given off from the sur-face of the acid, (called electrolyte).This gas is a mixture of oxygen and hy-drogen and it is very explosive. On thisaccount, the battery ought to be keptaway from all flames.

The acid spray is quite corrosive andit should be kept away from carpets andupholstering. The most used device fortesting whether a storage battery is fully


charged, or otherwise, is called a "hy-drometer" and it can be bought at anyautomobile or electrical supply store for50c to $1.00. The explanation of theworking of this instrument is simple.Sulphuric acid used in battery solutionsand known as "electrolyte" is heavierthan water alone. The hydrometer mere-ly indicates the relative weight of the so-lution as compared with that of purewater. As a charged storage batterydischarges, the sulphuric acid leaves thewater and goes into the plates, forminglead sulphate. When a battery is dis-charged, a large amount of the acid hascombined with the lead compounds inthe plates. Naturally, as the solution isweak in acid, it is lighter, and the floatof hydrometer sinks deep. But when abattery is fully charged and the acid isin the mixture, the latter has becomeheavier, thus forcing the hydrometer toride high.

The same action is noticed in swim-ming. It is much easier to learn in saltwater, than in fresh, because the saltwater, being a lot heavier, buoys a per-son up. It is even more marked for aperson swimming in the great Salt Lake,in Utah. Here the water is so salientthat it is very heavy arid it is impossiblefor a swimmer to sink in it. Going stillfurther, if you take a pan of mercuryand lay a flat iron in it, you will findthat the iron itself will float on the sur-face of the quicksilver. -

In reading a hydrometer the line rightopposite the surface of the liquid isused. Where the water touches the floatthere will be a little curve in the sur-face, but no attention is paid to this.When we say the hydrometer reads1.220, we meant that the lever of theelectrolyte comes opposite that point.This is illustrated in Figure 1. Onlythe float of the hydrometer is shown. Itis ordinarily contained in a glass syr-inge which is used to suck the liquidout of the battery cell. The float con-sists of three parts: the upper part orstem is marked with lines and figuresshowing the condition of the battery;the middle is the float chamber and ishollow to make it light; the lowest partis a weight and is usually filled withlead shot, so that it will sink and holdthe hydrometer right side up. Often-times the lead shot are held from rat-tling by a small amount of sealing wax.

A fully charged battery should readnearly 1.300. A specific gravity of 1.260

indicates a quarter discharged battery.1.225 shows that it has been one-halfused; 1.185, three -fourths gone and1.150 entirely discharged. Under nocircumstances is it advisable to letany battery get more than three-quarters discharged, because the forma-tion of a hard crust of lead sulphate in-creases so rapidly, that it is difficult toreduCe it by recharging. A storage bat-tery should never be left in a dischargedcondition, but should be recharged againwithout delay. Another important pointto remember is that a fully charged bat-tery (even if it is not used) will grad-ually discharge itself through electricalleakage in from 10 to 15 weeks. Or-dinary water from faucets or wellsshould not be used to make electrolyteor refill batteries on account of the ironand other impurities which it contains.Boiling won't help. Use nothing, but dis-tilled water and also chemically pure sul-phuric acid. They can be obtained atany garage.

Hot weather is severe on storage bat-teries, as it causes the water to evapo-rate much faster during this period thanat other times, thus uncovering the topsof the plates, and allowing the actionof the electric current to bend and twistthem until they are no longer useful. Anew battery then is required, which un-fortunately is quite an expensive pieceof equipment. Keep a close watch onthe water, adding to it twice a month.The acid does not evaporate and needsreplacing only if it has been spilled orhas leaked away through a cracked jar.Caution, in making up acid electrolyte;always pour the acid slowly into thewater, stirring it with a glass rod; donot reverse this proceeding or it will flyup into your face.

Overcharging a battery in the slimmertime will also heat the plates and elec-trolyte, causing evaporation from thetops of them and ruining the battery.As a matter of fact, the evaporation ofwater in a battery is continuous in coldas well as hot weather, although it isheavier during the latter months. An-other cause of battery trouble is charg-ing while the level of the electrolyte islower than the tops of the plates. If thesolution covers only one-half of theplates' surface, a normal charging rateacts on the lower half as if a doubleamount of current were being sentinto a battery, with the result thatthe plates not only buckle, but also a

loosening of their active material occurs,which will therefore fall to the bottomof the cell where it is not only useless,but short-circuits the plates if it pileshigh enough. Rapid overheating causesdamage, resulting in considerable ex-pense later.

Inexperience or carelessness in under-charging, if continued for some time,also makes the plates become harder andoffer greater resistance to the chargingcurrent. Should a normal charging cur-rent be sent into a battery in the abovecondition, it will produce enough heat tomake their plates buckle.

Winter weather is also hard on sto-rage batteries; they should not be keptin any place where they will freeze, asonce frozen, a storage battery is totallyand permanently ruined. Freezing causesthe grids in the plates to expand andcrack, thus allowing their "active mate-rial" to soften and drop to the bottomof the container. The greatest damageis done when a battery freezes while itis in a discharged condition. The safestcourse to pursue in the winter time isto keep the battery fully charged,whether it is used for radio work or onyour automobile.

It is a fact, proved by experience, thata fully charged ;battery will stand alower temperature than one that is dis-charged; the contrast between them isvery interesting. Thus one fully chargedwon't freeze until a temperature of 70degrees below zero is reached, while adischarged one freezes at 14 degreesabove zero. A quarter discharged bat-tery congeals at 60 degrees below zero.and if half discharged, at 20 degreesbelow zero. Another point to be re-membered in the winter is that when dis-tilled water is added to the electrolyteto maintain its level above the tops ofthe plates, the water must be thoroughlymixed with the solution before a batteryis exposed to the possibility of freezing.Should the water not be well mixed withthe electrolyte, freezing and damagingof the battery will result, even thoughthe latter be fully charged.

The best way to stir the electrolyteand water is to charge the battery for ashort time after it is full. In this waythe bubbles and gases, which are givenout, will mix up the solution perfectly.In case this is not possible. then by suck -ins the electrolyte up and down with ahydrometer syringe, the same resultsmay be obtained.

ULY 1, 1924 RADIO PROGRESS 21

American RadioDUTCHMAN ARRESTED FOR

SENDINGThe decision that it is not a crime

for an experimental radio amateur ofHolland to communicate with hams inthis country has helped the standing ofamateurs in the Netherlands, accordingto a report received by the AmericanRadio Relay League.

Even after a prominent French tele-graph amateur was decorated with agold medal for the skill with which hetalked across the Atlantic ocean on shortwavelengths, amateurs in Holland wereregarded as something equivalent to theboll weevil. The authorities were in-clined to think they were a menace totheir community.

The science of radio among the youngmen of the country had kept abreastof progress much better than the laws,with the result that H. J. Jesse, Jr., aprominent radio experimenter at Leiden,Holland, was made the defendant thatthe, courts might decide whether it waslawful for a citizen to transmit.

It was charged that Jesse's telegraphand telephone station was not intendedfor public communication and that mes-sages had been exchanged "without au-thority having been obtained from theminister of Wa.terstaat." (That's whatthey call the Radio Inspector.) He hadin fact, taken part in trans -atlanticradio tests and communicated withamateurs in the United States as farwest as Nebraska.

The defense pointed out that regulartelegraphic communication in competi-tion with commercial traffic was not 'in-tended and that the case was in theclass with work concerning laboratories.The clerk of the open ministry con-gratulated the defendant for havingcommunicated with a station in America.It was shown the defendant was notguilty and the case was dismissed.

AIRSHIP GOES "ON THE AIR"Rochester, N. Y., recently showed

that radio messages can come from apoint high up in the air as well as"through it." The radio operator onthe Navy's big airship Shenandoahgossiped for a while with radio ama-teurs below.

Relay League"To the Rochester amateurs," read

one message in code. "You are the firstbunch that have waked up to -day. Bestregards."

This was not a casual greeting, at-tempted as a pastime for the Shenan-doah's crew, but part of a systematicprogram for testing out the possibilitiesof short wave amateur communication.Some time ago the American RadioRelay League learned from the NavyDepartment that a short wave trans-mitter was being installed on the air -'ship for the express purpose of enablingits operator to communicate with ama-teurs should it be needed in emergencyduring flights.

The radio outfit on the Shenandoahis now regarded as the most completeof any ever installed on an aircraft; ithas facilities that allow ' the use ofpractically all wave lengths from 100meters to the long waves commonlyused by big commercial stations. Theadvantage of the complete equipment isto give the crew of the airship a chanceto avail itself of assistance, for direc-tion finding and other purposes, of allclasses of radio stations which would beuseful in time of emergency.

Even the broadcast band has not beenexcluded from this 'arrangement, for theShenandoah's operator, after sendingthe foregoing message to amateurs,shifted over from code to voice andgave the 'following message to stationWHAM:

"We have been hearing your broad-cast station WHAM, at Rochester, andit is coming in fine. If WHAM caresto, they might report our position tothe Naval Air Station at Lakehurst."

The operators at WHAM immediatelyforwarded the telegram to Lakehurstand then turned on the transmitter andinformed the Shenandoah they hadcomplied with the request.

LISTEN FOR "ARCTIC" ON 120METERS

William Choat, radio operator for theCanadian Government Steamer "Arctic,"which is leaving Quebec the first of Julyon her annual trip to Baffin Bay, maybe the first amateur operator to relayback to Canada and the United States

the complete details of the winter ex-periences and home -coming arrange-ments, of Captain Donald B. MacMillan,Arctic explorer.

The departure of the "Arctic," underthe Northwest Territories Branch of theCanadian Department of the Interior,comes at a time when the arrival of day-light in the Far North is beginning toshut off the radio contact between Mac-Millan and radio amateurs of the Ameri-can Radio Relay League in Canada andthe United States.

The radio messages that have comefrom Donald Mix, the explorer's radiooperator last fall and winter, have 'be-come gradually less frequent as darknessbegan to leave the polar regions. Oflate there have been only a few weakmessages that have sufficed to show the"Bowdoin's" crew have come throughwithout hardship. The last one told ofthe explorer's plan to start for homesoon.

This year the "Arctic" will carry ashort wave I. C. W. (interrupted con-tinuous wave) outfit which will enableits operator to transmit on the amateurwavelengths between 100 and 150 meters.This equipment is in addition to hertwo regular sets, consisting of a stand-ard 600 -meter 2 -kw. spark transmitterand a continuous wave transmitter work-ing on a 2,100 -meter wavelength.

The Radio Branch of the Departmentof Marine, which looks after the radioequipment on the "Arctic," wants tocarry on tests with amateurs of theAMerican Radio Relay League in Can-ada and the United States, and had thespecial short wave equipment installedfor this purpose.

The call which has 'been assigned tothe "Arctic" is VDM, while that of Mac-Millan's ship is WNP. Special permis-sion has been granted for all Canadianlicensed amateur stations to use thewavelength of 120 meters during speci-fied hours, although transmission on thiswave will not be permitted for any othercommunication.

In order that amateurs will knowwhen to be at their stations for com-munication with the expedition, a defi-nite schedule has been arranged during


which Mr. Choat will listen for signals.He will stand watch on the short wave-length daily, except Wednesday and Sat-urdays from 11 p. m. to midnight, East-ern Standard Time. Saturday, however,the hours will be extended from 11 p. m.to 3 a. m.

The "Arctic" is a wooden ship of 762tons gross and carries sails in additionto her engines. As it is impossible toinsulate the heavy guys which hold thethree 80 -foot masts, the ship is not re-garded as ideal for radio work, althoughit is expected that this handicap can beovercome by the use of high power.

The ground for the radio equipmentis provided for in the form of a copperplate secured to the side of the ship. Ifthis should be torn off when the vesselencounters ice floes, it will become nec-essary to utilize the engine propeller.

NOW SAY DOCTOR MAXIMHiram P. Maxim, the inventor, upon

whom the honorary degree of Doctor ofScience was just conferred by ColgateUniversity at its 106th commencement,has been president of the American

Radio Relay League from its beginning.In fact, it was Dr. Maxim who firstthought of organizing a non-commercialassociation of radio amateurs, and fromthat time to this, he has championedthe cause of the transmitting amateursof the country.

This new honor comes at a time whenDr. Maxim's work in behalf of amateurradio is beginning to secure recognitionfrom radio experimenters in all parts ofthe world. In recent years long distancetests of the A. R. R. L. with amateursin Europe, Australia, New Zealand andSouth America have brought the ama-teurs of this country into world-wideprominence, which gave rise to Dr.

Maxim's election as president of theTemporary Committee of Organizationof the International Amateur Radio

Union.This committee is designed to knit to-

gether the radio societies of the worldin the same way that the AmericanRadio Relay League has done with thosein the United States and Canada. In-terest in amateur radio in foreign coun-tries is increasing fast, and the proposed

international association will be a pow-erful influence in world affairs.

The international union of amateurswill bring to the experimenters of for-eign nations many of the privileges en-joyed by telegraph operators in NorthAmerica, as well as recognition of theirvalue in times of emergency. The ama-teurs of the United States have fre-quently been a wonderful help in areasaffected by storms and other disasters.Their merits have been recognized by therailroads and the government.

A WIRELESS QUESTIONNAIREA check-up of amateur radio condi-

tions in all foreign countries is beingmade by the American Radio RelayLeague to learn the amateur progressthroughout the world. In recent monthssending operators have been at work incountries where it did not seem possiblethere could be the slightest interest inradio.

Apparently there are few places whereexperimenters cannot obtain equipmentfor building radio sets if they persist.In countries where their existence hasnot been recognized, they are called"bootleg" operators. The radio laws inmost countries are poor.

With these conditions in mind, CharlesA. Service, assistant secretary of theA. R. R. L., has sent this questionnaireto radio societies in about twenty coun-tries:

"Digest of government radio laws nowin force or pending, relative to amateurradio, both receiving and transmitting.

"System of call letters used? Nu-merals, letters or combinations? Arethey assigned by the government or in-dividuals? Is the call list publishedand by whom? Cost?

"What is the name, title and addressof the government department or officialin charge of radio activities in yourcountry?

NEW HIGH POWER STATIONSSTARTING

The Class B stations are the powerfulbroadcasters, which can be heard over alarge part of the United States. TheUnited States Department of Commercelists 49 Class B stations at present, and14 more are being built. Some of thesehave not been revealed to the public asyet, but bigger stations are alreadyplanned for Chicago, Cincinnati, Denver,Hartford, Hot Springs, Huston, NewOrleans, and New York.

Broadcast Bill delights in golf,And will improve his play,

By following the golfing "pro"Who broadcasts every day.

At home last night he took a ballAnd placed it on a "tee."

He swung,-and tho he missed the ball.He made a "hit," you see.

-By Del.


NOVEL TOOLS FOR THE FANTwo rather interesting tools have just

been put on the market by Stevens &Company. One of them is a Spintitewrench for turning round thumb screwsor nuts. Such nuts are used for thefour terminals of vacuum tube sockets,as well as on many other places in theradio. It has always been rather awk-ward to tighten these with pliers, es-

pecially in a compact set. This tool, asshown in our picture, has a large num-ber of sharp teeth on the inside of a

Fig. 1. Wrench for Round Nuts

tube, which fits tightly over the nut.This tube has a hole which is bell -

mouthed at the end. This allows it tofit tight on a nut, even though it mayvary a bit from standard size. By push-ing this wrench down over the head ofthe nut a good grip is obtained and it iseasy to turn it down tight enough sothere is no danger of a loose contact.

Vise Will Not Mar Threads

Another new tool made by the samecompany is a Screw Clamp. This is asort of vice, but as shown in Figure 2,it has three holes tapped in the jaws.These take numbers 6, 8, and 10, screws,which are the only sizes used in mostsets. By clamping a screw in one ofthese holes, it can be held securely whileit is cut to the right length, or filed asdesired. In this way there is no dangerof marring the thread. This will be ap-prociated by those who have found theend of a screw so badly damaged that-7J iq next to impossible to start the nuton it.

Cutting DownOftentimes you have heard the an-

nouncer say, "One minute, please," andthen after waiting five minutes by yourwatch have wondered haw he gets thatway. Of course, it is not the director'sfault, as it takes considerable time toget the artists in place, and being some-what temperamental, they have to betreated in a leisurely fashion.

But station WTAM, Cleveland, theradio station of the Willard StorageBattery Company, has recently tried anexperiment in reducing this waiting timeby broadcasting alternately between twostudios. On the night of May 28 theymade a record for a new type of broad-casting.

An average of three seconds was main-tained between numbers on the programin spite of the fact that alternate se-lections were rendered at two points,seven miles apart.

The stunt was worked between theCleveland Plain Dealer studio and theWillard station of WTAM. Half of theartists were at one place and the restat the other. All the announcing wasfrom the Plain Dealer studio.

Especially interesting is the fact thatthe switch over from one point to theother was accomplished without the aidof any signal or communication otherthan the radio itself. This was doneby use of a code word spoken so thatlisteners were unaware that a code sig-nal for the switch over was being given.

Both studios were equipped with re-ceiving sets tuned to the station's wave.The Plain Dealer station led off and thefirst number was followed by the an-nouncer explaining what was being done.He ended his announcement with the--ord "studio" which was the code sig-

Fig.

k1/4Vi A

2. Screw Clamp

Waiting Timenal for the operator in the transmittingroom to cut in, and to the artist at theWillard 'studio to start broadcasting.

As the music stopped at the Willardstudio, the operator threw his switch,cutting back to the Plain Dealer stationwhere the announcer had been listeningon a receiving set. Allowing three sec-onds to make the change in connections,the announcer started his statement ofLille next number.

"Studio" being the last word of everyannouncement, was the signal for theoperator. to throw his switch from onestudio to the other but to the listeningradio fans it was just part of the an-nouncement.

While one station was broadcasting,artists at the other were taking theirplaces, to be in readiness to follow. Inthis way shorter intervals elapsed be-tween numbers than could have beenpossible if all the broadcasting had beendone from one place.

REINARTZ RECEIVES REWARDJohn L. Reinartz, famed radio experi-

menter of South Manchester, Conn., washonored at a special meeting at theSeaman's Church Institute in New

York recently when he was presentedwith a cup by the special committee ofthe Executive Radio Council of the Sec-ond District. The cup is 'to be offeredannually to the amateur who contri-butes the greatest advancement in radiocommunication for the year.

This is the first time this cup has beenawarded, and Reinartz has thus beensignally honored by the amateurs of thesecond district for his accomplishmentsin the development of receiving andtransmitting circuits, which made re-cent transatlantic' amateur work pos--ale. The cup will be awarded on thesame basis as the Institute of RadioEngineer's "Liebmann Pr i z e,"-f ormerit only.

DISCARD ALL YOUR BATTERIESDon't miss the next issue of RADIO

PROGRESS, as you will find a de-

scription of a new method of dispensingwith all your batteries, "A," "B" and"C."

y RADIO PROGRESS JULY 1, 1924

Fone Fun For FansHe Didn't Shake-Much

Sam had passed through a harrowingexperience. He had seen a ghost.

"Ah jes' come out of de cowshed," hesaid, "an' ah had a pail of milk in mahhand. Den ah hears a noise by de sideof de road an' de ghost rushes out."

"Did you shake with fright, Sam?"asked one of his dusky audience.

"Ah don't know what ah shook wid.Ah hain't sayin' suttin ah shook at all.But when ah got home ah found all demilk gone, an' two pounds o''butta in depail."-Progressive Grocer.

Professor (in engineering class)-What's a drydock?

Stude-A physician who won't giveout prescriptions.-Crosley Radio Week-ly.

He Gets a, DateShe-Isn't the sunset beautiful?He-Yes, but what chance has it with

your face around ?-Tennessee Tar.

A Case in the Short Circuit CourtA chap for assault and

battery and brought before the judge.Judge (to prisoner): "What is your

name, your occupation, and what areyou charged with?"

Prisoner: "My name is Sparks, I aman electrician, and I am charged withbattery."

Judge: "Officer, put this guy in adry cell."-The Inland Merchant.

The Goodnight MessageThe patter of tiny feet was heard on

the stairs and Mrs. Blank raised her

hand for stillness among the membersof her bridge club.

"The babies are going to give me theirgoodnight message," she whispered."Listen, it always gives me a feeling ofreverence."

The silence was intense as the womenlistened: "Mama," came the shrill whis-per, "Willie found a bug."-CrosleyRadio Weekly.

ForetasteLittle Bob: (about to go out with

mother)-4Mama, you must take somemoney with you."

Mother-No, Bob, I'm not going to useany.

Little Bob-Yes, you must have moneyfor chocolate; I might start crying onthe street, you know.-Detroit News.

Blame Father"How'd you get so bowlegged?"

asked one corner ornament of the otherin the neighborhood of Pike and Madisonstreets on the lower East Side. "Didthey let you walk too soon ?"

"Naw," growled the bow -shinned one;"my old man used to swat flies on myhead, an' he swatted me so hard he bentmy pins."-Radio Merchandise.

He-If you hadn't taken so long get-ting ready, we should have caught thattrain!

She-Yes, and if you hadn't hurriedme so, we shouldn't have had so long towait for the next one!-Crosley RadioWeekly.

THIS BEATS 'THE AIRPLANEThe fact that radio waves can be made

to go "there and back in nothing flat"was demonstrated at WTAM, radio sta-tion of the Willard Storage BatteryCompany, broadcasting from the Cleve-land Plain Dealer studio.

A late dance concert of request num-bers was being put on the air when afan called the studio by long distancetelephone from St. Thomas, Ontario,placed his loud speaker to the telephoneand sent back over the wire the samemusic that was being sent out by radiofifteen feet away.

The speed of the round trip of the sig-

nals was so great that the music cameback from Canada at the same instantthat it was going into the microphone inthe next room.

Here is the circuit of the music; tele-phone wires carried the signals from thestudio to the transmitting set, sevenmiles away. From there the ether car-ried them to St. Thomas, about 100

miles, straight across Lake Erie. FromSt. Thomas they were put on the wireagain, going about 400 miles around thelake to get back to the studio. And thereturn was instantaneous with the start.

Some one has suggested that if the(speed could be increased just a little

more so that the music returned to thesending just an instant before it left, itwould save an immense amount oftrouble, as the artists could be dispensedwith entirely, by hooking the receiverup to the sending station. This wouldresult in a sort of perpetual motion.

DEAD END TURNS ARE BADSMost radio sets contain a tap switch,

working on switch points, which are con-nected to taps on a coil. This may bea variocoupler, or perhaps a spider webcoil and the taps are often locatedfrom one to ten turns apart. These coilsare usually made too big. This isnecessary, since the manufacturer doesnot know what wave lengths you aretrying to get, nor can he tell how shortan aerial you are going to use. Thelength of the coil is governed verylargely by these two considerations-the longer the wave length, the morewire you need in the coil and antenna.But for a given wave length, the longer,the aerial, the shorter must be the coil,since it is the sum of the two work-ing together that picks out the sta-tion you want. If the manufacturers ofyour radio knew you were going to usean aerial of exactly 100 feet they couldcut down the wire in your coil so thatthe longest wave length would be re-ceivd on the last tap.

But after you have installed your set,you will find that most of your work isdone on only a few buttons of the in-ductance switch. Say there are tenswitch points and you use only Nos. 4,5, 6 and 7. Then the extra turns beyondthe seventh are not doing you any good.On the contrary, they are really causingharm. This is for two reasons. First,the extra wire reduces the sharpness oftuning somewhat as it tries to vibrateat its own particular wave length. Be-sides that, additional and unnecessarylasses will be created in this superfluouswire. To avoid these two troubles, itis well to unwind and discard the extraunnecessary turns. By doing this youhave increased both the selectivity andalso the loudness of your set.

In this illustration Taps No. 1, 2 and3 were not used either, but of course,the wire to which they are connectedcannot be discarded as it Is in circuit,since the electricity flows through it be-fore getting to taps 4 to 7. The pres-ence of these switch points, while useless,is not detrimental.

JULY 1, 1924 RADIO PROGRESS .45

Some Live Problems in RadioStatic Hardly Bothers theCommercial Station Now

By E. F. W. ALEXANDERSON, Consulting Engineer General Electric Co.

Fr HE real romance in research lies in precedents; practically every problemthe early stages. When long distance was a new one and had to be solved by

radio was first put to important use, new means. In addition to this elementduring the war period, many thrilling of newness, there was the additionalepisodes occurred.

One of these took place in a stationthat had been hastily reconstructed andforced) into the service of maintainingcommunication with France while wewere yet building and experimenting inradio. Originally the station had beenof the Marconi type, but had become ob-solete, and its reconstruction consistedin setting up a high -frequency alternatorand building a primitive transmittingplant around it. Trouble soon developedin the antenna insulation. Often an in-sulator would blow up with an explosion,but sometimes it would give a warningby a flickering light.

Spy is DiscoveredThe station was strongly guarded by

marines who were quick on the trigger,and one dark night the guard saw aflickering light in one of the woodenshacks which was used to house the out-door tuning coils. He thought it was anenemy spy and would not take anychances, so he peppered the shack withhis automatic rifle. After a little whilethe insulator exploded and the stationwent dead. This gave the marine con-vincing proof that somebody had planteda bomb.

Firearms played no part, however, inthe final solution to this problem of in-sulator breakdown. It was technicalknowledge acquired by scientific investi-gation that furnished the means ofeliminating the trouble. This is but onesuch incident.

Not Many Precedents HereThe development of commercial radio

in all its phases has afforded an unusualopportunity for the application of scien-tific engineering methods. In mostother branches of engineering there aremany previous cases to help the engi-neer in his choice of methods. In radiocommunication there were but few such

complication of having to deal withforces of Nature which are not undercontrol and therefore subject to the lawof chance. At the outset these laws ofNature were very little understood andall of them are not yet entirely known.For instance, what are the causes offading and exceptional increase of signalstrength, or periodic fluctuation of sig-nals? It can only be stated that thesephenomena are observed to have some-thing to do with the change from day-light to darkness and that they are morepronounced at the shorter wavelengths.

That great enemy of radio communi-cation, atmospheric disturbance, orstatic, is by this time pretty well un-derstood and under control. It is reallythis fact that makes commercial radiocommunication at all possible.

Making a Business of CodeTo bring about order and reliability

in sending signals, we must take intoaccount the effect of probability andaverages. This can be readily under-stood by radio amateurs or broadcastlisteners. When we receive clear signalsfrom across the continent, we tell theworld about it. Similarly, when thesportsman catches a big trout, he tellshis friends of it as an event. But, pro-fessional fishermen succeed in furnish-ing fish for the market every day. Thusit is the aim of the radio engineer toexplore the sea of the ether, to weatherits storms, and to provide continuousservice day and night.

The transoceanic radio station is apower station. Its input is kilowattsand its output is words. The problemof radio engineering is to fix the relationbetween these two. This relation be-tween kilowatts and words is a chaincomprising four separate links which arebeing studied by specialists in the fol-lowing subjects:

(1) Efficiency and cost of sending.(2) Wave transmission and fading.(3) Static.(4) Speed of sending messages.

Efficiency and Cost of RadiationThe first subject deals with the radio

power station and the aerial. Fourtypes of antennas are used in the sys-tem of the Radio Corporation ofAmerica. Three of these are adapta-tions of old structures, but the fourth,the Radio Central antenna on Long Is-land, is designed from the ground up.

Figure 1 shows two different styles ofaerial. The difference depends entirelywhere the lead-in is attached. If itcomes from the ends of the wire, asshown at L, then from the similaritywith the letter, it is called an "L" type

Fig. 1. L and T Aerials

aerial. But if the lead-in comes fromthe centre, then it makes a "T" antenna.Of course, both lead-ins should never beused together, as shown in the diagram.Either L or T must be omitted. Figure2 shows another well-known type of con-struction. It is called the umbrella.Only one pole is needed, and from itstop the various aerial wires radiate outin all directions. From four to ten ofthese may be used. Part way down aninsulator is inserted and below this thewire acts only as a guy. Figure 3 showsthe Beverage antenna, which will be de-scribed in greater detail a little later.

The radiation efficiency of an aerialdepends upon the effective height, theground resistance and the wavelength.In antennas for long waves most of theenergy is absorbed locally and only asmall proportion is radiated.


The object of modern aerial design hasbeen to get the biggest radiation for agiven antenna cost, as well as the big-gest for the power consumed. These tworequirements are opposed to each other,and, as usual in design, a compromisemust be arrived at. A high radiationefficiency can be had only by the use ofa very expensive antenna. There is athird requirement that the operatingvoltage must be kept within practicallimits. The best compromise betweenthese needs has been obtained in the longmultiple tuned Beverage antenna withmoderately high towers operated at highpotential. The Radio Central antennahas twelve ground connections distri-buted over a distance of three miles, andhas 300 miles of wire buried in theground. Through these devices the

Fig. 2. Umbrella Aerial

ground resistance has been reduced to1/20 ohm. Antennas of types previouslyused had ground resistances of about2 ohms. The losses in the ground havethus been reduced to less than 3 per cent.

The practical measure of the powerof a transmitting station is not theenergy radiated, but the product of theamperes in the aerial, and its effectiveheight. This unit of radiation is calledthe meter -ampere.

Tremendous PowerIf we have an aerial 60 feet high

(equivalent of about 20 meters) and theammeter in the line reads 10 amperes,then the radiation will be 20 x 10 or 200meter -amperes. The radiating powerused in a typical transoceanic telegraphstation is about 50,000 meter -amperes,whereas a representative broadcasting orship station has the power of only a fewhundred meter -amperes. The distancethat can be covered under normal day-light conditions by a transmitting sta-tion is about proportional to the num-ber of meter -amperes used, provided thata wavelength has been selected which issuitable for communication over such adistance.

Wave TransmissionThe second subject is wave propaga-

tion. The longer the wavelength thegreater is the cost of antenna structureand the lower is the radiation efficiency.From this point of view, it would seemthat long waves would be undesirable.If sending were limited to the hours ofdarkness, this would be true, but in com-mercial communication the daylighthours are the most important, and dur-ing those hours the absorption of theshort waves is so great that better andmore economical communication is ob-tained by the long waves. For eachdistance there is a certain wavelengthwhich gives the best compromise betweenabsorption and radiation efficiency.

One Cause of FadingThe absorption of short waves is high

over dry sandy ground. It is also foundthat irregular land and water break upshort waves into several paths whichmeet again in such a way that the oscil-lations combine. The waves will thusunite sometimes in phase (in step) andcause an increase of signal strength, andsometimes out of phase thus causing pe-riodic fading of the signal. Practicalexperience can be summed up in the rulethat the most economical wavelengthsfor reliable daytime communicationover any distance is about 1/500 ofthe distance. It is about 3,000 milesfrom New York to Europe. As there arearound 1,600 meters to the mile, thismakes the distance 4,800,000 metersacross the water. Dividing this by 500as just described, we get the answer ofabout 10,000 meters for the best wavelength for talking to Europe. This isone of the most popular frequencies inuse to -day for this service.Atmospheric Disturbances "Static"The third subject deals with the at-

mospheric disturbances. Our modern re-ceiving systems eliminate about nine -tenths of the static, but the balance leftdetermines the speed of receiving themessage.

We now know enough about these sub-jects to enable new radio circuits to becalculated with the same ease as we de-sign a motor. The engineer starts at thereceiving end and gathers his facts andreasons backward in order to determinewhat power, wavelength, etc., the trans-mitting station must have to serve thepurpose most economically.

This can best be illustrated by an ex-ample. The first step in planning a new

station is to make measurements ofstatic at the places where the signals areto be received. These measurements,hould extend throughout the season ofthe year when conditions are worst.

All disturbances were originally called"static," 'because they were thought to belike static electricity. The idea whichis the basis of modern work is different,however. The ether is imagined to be adisturbed ocean with waves of everylength rolling in from all directions.These waves are of the same nature asthe signal wave. The disturbing waves,which are of different length from oursignals, can be shut out in the same waythat is used for cutting out other sig-nals, that is, by tuning. But disturbingwaves which have the game length asour signal are just like it in every way,and so pass through the tuning systemlike the signal.

Elimination of "Static"This shows that some additional way

must be found if we want to get rid ofthe static which happens to be the samewave length as the station we are lis-tening to.

If a radio set is built to be sensitiveto waves coming from only one direction,then static from any other point can beshut out even if it does have the samewavelength. This is the principle ofdirectional reception, on which the re-ceiving stations of the Radio Corpora-tion are based.

Each improvement in the direction ef-fect of the receiving system has helpedspeed up traffic. The development of the

O. Two OR MORE WAVEL0N4,115 >

0 la

Fig. 3. The Beverage Invention

receiver at Riverhead, Long Islhnd, hasalready reached the point where mes-sages from Europe are received on anaerial 30 miles long and signals fromSouth America on another antenna 20miles long. The aerial consists of twotelegraph wires mounted on woodenpoles.

The Wave AntennaThe basis of this system is the so-

called "wave antenna" invented by Bev-erage. In its simplest form it consists


of a single wire, one wavelength long,mounted on telegraph poles or even laidon the ground. This antenna is sensi-tive to waves from only one direction.The radio wave coming in from theether starts a vibration in the end ofthe wire and travels along this conduc-tor with the velocity of light. In themeantime, energy is continuously addedto the wave in the wire from the etheroscillation which travels alongside it, sothat the wave in the wire keeps buildingup and so is strongest at the far end ofthe conductor, where the receiving set islocated.

o f --->Fig. 4. Theory of

As actually constructed, the aerial isseveral wave lengths long. The oneshown in Figure 3 equals three waves.Notice that the aerial has a ground con-nection through a coil spaced each wavelength apart. The coil is adjusted byexperiment, so that instead of oscillatingas a whole, the antenna is broken upinto several vibrating sections. This islike the clothes line experiment, whichhas been mentioned before. Figure 4shows a clothes line 30 feet long, whichis vibrating in three ten -foot sections.It will be easily appreciated that therewill be a lot more energy in this line,than there would in only a single ten -foot length, but the speed of oscillation,that is the wave length, is the same ineither case.

Won't Work for BroadcastingAnother advantage of this type of con-

struction is that by having severalgrounds in parallel, the resistance is re-duced considerably below that of asingle ground. Of course, such an aerialwill not work for broadcasting. It hasto be tuned to receive only a particularwave length from one certain direction.As an illustration, if you wanted to hearKDKA only, then you could build suchan antenna and the volume of tonewould be deafening, but you could notget another station at all. This is noobjection when considering a trans -At-lantic station, which is built to workwith only one other place in Europe.

Selection of Receiving SiteStatic usually comes from the land

side and so if the signal comes from theocean we can design the receiving systemso that it reduces the static, but not thesignal.

An interesting case was found whichshows this action clearly. It was de-sired to send a message from A to B(Figure 5). But unfortunately, power-ful static was flowing towards B fromthe same point. It would have been im-possible to keep up communication onbad days. This was overcome by build-ing Station C off to the side as shown.

the Wave Antenna

A could send to C without any trouble,because it lay outside the static belt, andC could relay the message on to B be-cause it was nearly right angles to thedirection of the static flow, and so theBeverage antenna would pick up the sig-nal along the line in which it pointed,but did not bring in any static.

Two lines of favorable direction werethus substituted for the one less favor-able; just like a sailboat which re-quires two tacks to arrive at a pointstraight to the windward. This is avery unusual case, but it shows that apractical solution can be found evenunder most unfavorable circumstances.

Speed of Commercial SignallingThe fourth subject deals with the

speed of reception. It has been found inwireless that the quickest signallingspeed depends on the relative loudnessof the signal and the static. Here is thereason:

The shortest part of a code letter is adot. The letter D, for instance, is madeup of a dash followed. by two dots, likethis, -.. and of course the faster thespeed the shorter must be the dot. Soif the loudness is kept constant, then thetotal energy in the dot sign must be in-versely proportional to the speed.

If a dot lasts for say one -fifth of asecond, it has used up a certain amountof energy, but if we let it run for onlya tenth of a second, obviously there willbe one-half as much energy as before.

When the strongest "bang" of static atany time contains as much energy as adot in the telegraphic code, it may bemistaken for a dot, or it may break upa dash into two dots, thus signaling thewrong letter. So it is necessary to sendcode slowly enough so that the totalenergy of a dot is somewhat greater thanthe maximum energy of a single atmo-spheric impulse. Thus if the wave am-plitude (or loudness) is doubled, thelength of the dot may be shortened toone-half. This explains why in practicethe sending speed is proportional to thepower and also why it is inversely pro-portional to the atmospheric disturb-ance.

Measurement of Signal and Static. It can thus be seen that in developingnew stations we must have accurate dataon the intensity of the static. Methodshave been developed for measuring sig-nal strength as well as atmospheric dis-turbances. The unit of measurement ismicrovolts per meter. The meaning ofthis term is "millionth parts of a voltper meter effective height of the receiv-ing antenna."

For instance, suppose we have anaerial thirty feet effective height. Thisis the equivalent of ten meters. Whenwe measure the signal strength, we find

Fig. 5. Outwitting the Static

the pressure is 1,000 microvolts, then thestrength of the signal coming in was1,000 divided by 10, which equals 100microvolts per meter. If the aerial hadbeen twenty meters high the readingwould have been twice as great, or twothousand. Dividing 2,000 by 20 gives us100 again, which is, of course, correct,as the strength of the signal comingthrough the air does not depend on whatkind of aerial it will strike shortly.Static strength is measured in the sameway.

Measuring instruments have been de-veloped by which charts can be made toshow by curves the intensity of the sta-

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tic in all directions. Such charts aremade for every hour of the day.

One of these charts is shown in Figure6. This tells us that most of the staticis coming in from the North, as thedistance from zero in the center out tothe point P is large. To the East andWest the static is not so bad, but thebest direction of all is toward the South,where it will be seen that only a littledisturbance is shown. In other direc-tions, like the northeast for instance, itis possible to find how strong the staticcomes in by drawing the line in that di-rection. Q shows such a line to thenortheast and from it we see that onlya moderate disturbance would bother usfrom there. If the diagrams throughoutthe year resemble the one shown inFigure 6, it proves that the best way dfsetting up an aerial would be to haveit run north and south, with the freeend to the south.

Static ChartsExamination of these charts will show

what portions of the static can be elimi-nated by directional reception and whatthe intensity will be of the static whichcannot be eliminated. Assume that thisinvestigation shows that the total staticfor the afternoon hours of the summeris 500 microvolts per meter. Receptionunder such conditions without the di-rectional receiving system would betotally impossible. Suppose, however,that the polar charts show that only 10per cent. of the static falls within thequadrant from which the signals are to

be received. The portion of the staticwhich cannot be eliminated has then astrength of 50 microvolts per meter(10% of 500). A transmitting stationthat can give a signal of 50 microvoltsper meter could then be expected tohandle traffic at a rate' of 20 words perminute during the worst hours of theday and at a higher rate during the re -

P

Fig. 6. Polar Static Curve

maining hours. If this is not fastenough to handle the expected volumeof traffic, it may be decided to use asignal intensity of 100 microvolts permeter. This would speed up recei,ving toa rate of 40 words per minute duringthe worst hours.

Prediction of Traffic CapacityInformation is now available on trans -

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mission efficiency, from which it can bepredicted what radiating power is neededin the transmitting station in order togive the desired signal strength at thereceiving station. Assume that a signalof 100 microvolts per meter requires atransmitting station of 50,000 meter -amperes. This would be a station of thesize used in transatlantic service. On theother hand, suppose that no attemptswere made to reduce static interferenceby directional reception and that it wasexpected to receive a message by increas-ing the signal strength. This would re-quire a strength ten times as great,which would mean a radiated energy onehundred times as great. Such use ofbrute force would not be practical noreconomically possible. These figures areright for most cases of talking to Eu-rope.

Talk Round the WorldThere is now a chain of American -

built stations around the earth whichare either in operation or in construc-tion. When the chain is completed, itwill be possible to link them together,and send a signal which will automati-cally be relayed from station to stationand circle the earth with the velocity oflight. If it is sent from New York, itcan be relayed over San Francisco, Hono-lulu, Shanghai, Sweden or Poland, andback to New York. It would arrive one -seventh of a second later than the timeit started.

The fact that radio telegraphy hasnow definitely attained the commercialstage does not mean that the end of itsdevelopment has been reached. By thecontinued application of scientific engi-neering principles to the solution of itsproblems, as they arise, radio telegraphservice will grow to fill a greatly ex-tended field of utility. But this is notall. The knowledge which has beengained in making radio telegraphy de-pendable is now available for applicationto broadcasting.' There is reason to be-lieve that the same principles will go along way toward eliminating the uncer-tainty that to -day attends the daily re-ception, over long distances.

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HURRAH FOR THE FOURTHAs you have noticed, we are

very patriotic in this issue, andhave the covers dressed in Red,White and Blue. The next thingto decide is how to celebrate thebig day. The general talk nowis to make the Fourth "Safe andSane." But when you spring thisidea on the boys, they do not taketo it very kindly. How can acompromise be effected betweenthe older folks, who frown ongiant firecrackers, and the young-er ones, who must have some ex-citement?

Radio Reconciles Them

This is where radio comes in.We venture to predict that thereis not a boy or girl in the countrywho would not prefer to have aradio set rather than a lot of fire-crackers. When you realize thata good crystal set, together withphones, can be bought for aroundfive or six dollars, it is hard toturn the youngsters down on thequestion of economy. Of course,this suggestion will not apply tofamilies who live more than 15or 20 miles from a good sizedbroadcasting station, for that isabout the limit which any 'ordi-nary crystal set will pick up. Theoccasional reports of 500 and1,000 miles are either made byunreliable persons, or else the pro-gram was received on the crystalas re -radiated from some nearbyuser of a high-powered vacuumtube radio.

So You Can Hear, TooThere is one further great ad-

vantage about giving the boys aradio set. It is something likepresenting your son with a trainof cars at Christmas time-thatis, he will probably complain be-

cause he does not get much of achance to play with it himself.For this reason, it is perhaps bestto suggest two or three pairs ofphones.

DISCUSSING DISTORTION

We might almost have said,"Disgusting distortion," as nextto the squeals from your neigh-bors' oscillating sets this is prob-ably the worst feature of radioat present. Some people use thisword without a clear understand-ing of just what is meant. Sup-pose you are listening to a concertfrom a distant station and it gets

hardly hear it. That isn't distor-tion. That's fading. Or perhapsin the middle of a song you heara terrible squeal. That is yourneighbor's set being improperlyoperated. Or, again, some onestarts putting in a load of coalnear by. That is static.

Turn Down Tickler

But when you hear a stationpretty well,-a man talking loudenough to be heard easily, but hiswords are very difficult to graspso that you have to put your wholemind on it before you can catchwhat he is saying,-then that isdistortion. It may come from anyone of three places. Perhaps it isin the set. If so, there may beseveral reasons; a tickler coilturned up too far will cause it.So will a tube which is improperlyadjusted. Poor audio transform-ers are also a source of suchtrouble.

Another place where this unde-sirable feature occurs is in theloud speaker. Sometimes a setwill operate very nicely using earphones, but when a loud speaker

is plugged in, the orator seems tobe talking with his mouth full ofmush. In such a case we nat-urally blame the horn. There hasbeen considerable improvement inthe last year or so in the matterof proper designs of this unit.The modern loud speakers are agreat improvement over those ofa year or two ago.

Blame the Station

The third place to look for thedistortion is in the broadcastingitself. When the sending stationhas its pick-up, (the microphonewhere the artist sings), connectedby a short line to the sending ap-paratus and the aerial, then notrouble is experienc=ed. But if, asis occurring more and more fre-quently, the performance is givenin one city and it is connected bylong distance telephone to thebroadcasting studio, 50 to severalhundred miles away, then seriousdistortion may be introduced bythe characteristic of the toll lineitself.

Why the R'sA wire line is quite different

from the ether in this respect.The latter is entirely non -selectivein its effect on sounds. The letterS and the letter T, for instance,are both reduced in loudness bythe same proportion as they aretransmitted through the air. But,unfortunately, this is not true ofa wire telephone line. When talk-ing over the long distance thesounds of some letters will be re-duced to half, while others willbe almost entirely suppressed. Asan example, the sound of R doesnot carry through very well. Thisis why telephone operators whenrepeating the number you have

Continued on Page 30

E5CR/DrSNOTE: In this section the Technical Editor will answer

questions of general interest on any radio matters. Any ofour readers may ask not more than two questions, and ifthe subjects are of importance to most radio fans they willbe answered free of charge in the magazine. If they are

Question. Why does the music stutterwhen the tap switch is moved slightly?

Answer. This shows that there is toomuch looseness in the tap switch, andfor this reason a poor contact is madebetween the switch point and the switcharm. This trouble occurs fairly fre-

quently in the average set. The remedyis simple. Take off the rotating armand bend the spring toward the contacts.When the arm is now replaced the ten-sion between it and the contact pointswill be considerably greater than before,and so the current will have no difficultyin flowing across the break. If the ad-justment is properly made, then no soundwill be heard in the receiver as theswitch handle is oscillated back andforth a small amount.

Question. What is the best way offinding out whether a trouble is in-

side or outside the set?Answer. It is a rather difficult mat-

ter to be sure in which of these placesthe trouble lies if reception is only fair.Of course, if nothing is heard it alwaysindicates that the set is out of order, foreven a poor aerial and ground will bringin some local music. The best way oftesting out the equipment in case localstations are heard, but no distance, is toborrow the aerial and ground of somefriend whose outfit is working well. Thedoubtful set may be transported as awhole with "A" and "B" batteries, un-less it is known by a meter test that thebatteries are in first class shape. If thisis the case, then the neighbor's batteriesmay be borrowed for temporary use tosave transporting this extra weight.Connect your radio to your friend's aerial

of special interest to the questioner alone, or if a personalanswer is desired, a charge of fifty cents will be made foreach answer. This will entitle the questioner to a personalanswer by letter. However, if the question requires consid-erable experimental or development work, higher rates willbe charged, which may be obtained upon application.

and ground. If now the distant stationscome in well it shows that your aerial orground is at fault, but if reception isnot any better on his aerial, which is al-ready known to be good, then the diffi-culty must lie in your set itself.

Question. What kind of rheostat isused in Crosley sets?

Answer. This is a rather specialrheostat, which is designed for use withall the different kinds of vacuum tubes.An ordinary 6 -ohm rheostat is satisfac-tory for WD -11, WD -12 and UV -200, buthas not high enough resistance for a199 or 201A. A rheostat should have aresistance of about 20 ohms to workthese latter tubes. It might be askedwhy a 20 -ohm rheostat wouldn't workwith a UV -200. There are two reasons.In the first place this takes one amperefor the filament current, and that is toomuch to run through a 20 -ohm rheostatwithout overheating it. Even if therheostat handle is turned so that theamount of resistance in the circuit isonly one or two ohms, the condition willnot be helped. These high resistanceunits are wound with fine wire and run-ning one ampere through such a smalldiameter causes too much heat.

A second objection is the fact that atwenty -ohm resistance does not havenearly as sensitive control as when usedwith a UV -200 tube. That is, a verysmall movement of the handle causes toobig a change in the brightness of thefilament. Crosley gets around thistrouble by building half the resistanceof coarse wire and the other half of fine.When a 200 tube is used, only the coarsewire is in circuit, and so the control is

accurate and there is no overheating.When a 201A is substituted, the controlhandle is turned around to the left toinclude some of the fine wire in serieswith the coarse. This is sufficient tobring the total resistance up to 15 or 20ohms as desired.

Question. Will a vernier condenserincrease the selectivity of my set?

Answer. No, a vernier condenser doesnot increase the selectivity or volume ofa radio. It is intended to do only onething, and that is to make it easier toadjust for any given wave length. Onceadjusted, the station is no louder orclearer.

DISCUSSING DISTORTIONContinued from Page 29

called will often say "thrrrrrree,"thrilling the R to make sure thatyou hear it.

Of course, the telephone com-panies have been working on thisproblem for a long time, and theyhave some long distance linesWhich by careful design have beenmade pretty nearly distortionless.Many of their wires are not fixedin this way. This accounts forthe fact that with the same setand loud speaker you will some-times get a speech through veryclearly when relayed from a dis-tant city, and at other times theenunciation will be very poor.This is noticed more with speechthan with music, since we knowwhat the words ought to soundlike, while distorted music may bethe fault of the artist.


UNITED STATES BROADCASTING STATIONSARRANGED ALPHABETICALLY BY

CALL LETTERSAbbreviations: W.L. wave length in meters; K.C., frequencies in

kilocycles; W.P., watt power of station.W.L. K.C. W.P.

KDKA Westinghouse Elec. & Mfg. Co.. East Pittsburgh -326- 920-1000K.131-'31 Westinghouse Elec. & Mtg. Co., Cleveland, 0 270-1110- 250KDPT Southern Electrical Co., San Diego, Cal 244-1230- 100KDYL Salt Lake Telegram, Salt Lake City, Utah 360- 833- 100KJ/1M savoy Theatre, san Diego, Cal 280-1070- 100KDYQ Oregon Institute of Technology, POrtland, Ore 360- 833- 100KDYX Star Bulletin, Honolulu, Hawaii 360- 833- 100KDZB Frank E. Siefert, Bakersfield, Cal 240-1250- 100KDZE The Rhodes Co. Seattle, Wash 270-1110- 100KDLF Auto. Club of so. Cal., Los Angeles, Cal 278-1080- 500KFAD McArthur Bros. Mercantile Co., Phoenix, Ariz 360- 833- 100KFAE State College of Washington, Pullman, Wash 330- 910- 500KFAF Western Radio Corp., Denver, Col 360- 833- 500KFAJ University of Colorado, Boulder, Col 360- 833- 100KFAQ City of San Jose, San Jose, Cal 360- 833- 250KFAR Studio Lighting Service Co., Hollywood, Cal 280-1070- 150KFAU In. Sch'l Dist. of Boise City, B'ise H. S., Boise, Id 270-1110- 150KFBB F. A. Buttrey & Co., Havre, Mont 360- 833- 100KFBK Kimball -Upson Co., Sacramento. Cal 283-1060- 100KFCF Frank A. Moore, Walla Walla, Wash 360- 833- 100KFCM Richmond Radio Shop, Richmond, Cal 360- 833- 100KFCZ Omaha Central High School, Omaha, Neb 259-1160- 100KFDH University of Arizona, Tucson, Ariz 360- 833- 150KFDV Gilbreth & Stinson, Fayetteville, Ark 360- 833- 200KFDX First Baptist Church, Shreveport, La 360- 833- 100KFDY *So. Dakota State College, Brookings, So. Dakota 360- 833- 150KFEL *Winner Radio Corp., Denver, Col 254-1180- 100KFEQ J. L. Scroggin, Oak, Neb 360- 833- 150KFEV Felix Thompson Radio Shop, Casper, Wyo 263-1140- 250KFEX Augsburg Seminary, Minneapolis, Minn 261-1150- 100KFEZ Amer. Society of Mech. Engineers, St. Louis, Mo 360- 833- 250KFFQ *Markehofiel Motor Co., Colorado Springs, Col 286-1050- 100KFFV Graceland College, Lamoni, Iowa 360- 833- 100KFFX McCray Co., Omaha, Neb 278-1080- 100KFFY Pincus & Murphy, Alexandria, La 275-1090- 100KFGC Louisiana State University, Baton Rouge, La 254-1180- 100KFGD Chickasha Rad. & Elec. Co., Chickasha, Okla 248-1210- 200KFGH *Le.and Stanford Jr. Univ., Stanford Univ., Cal 273-1100- 500KFGJ Mo. Natl. Guard, 138th Infantry, St. Louis, Mo 265-1130- 100KFGX First Presbyterian Church, Qrange, Tex 250-1200- SOOKFGZ Emmanuel Missionary Col., Berrien Sprs., Mich 268-1120- 250KFHD Utz Electric Shop, St. Joseph, Mo 225-1330- 100KFHF Central Christian Church, Shreveport, La 265-1130- 150KFHJ Fallon & Co., Santa Barbara, Cal 360- 833- 100KFHX Robert W. Nelson, Hutchinson, Ks 229-1310- 150KFI Earle C. Anthony, Inc., Los Angeles, Cal 469- 640- 500KFIF Bens,n Polytechnic Institute, Portland, Ore 360- 833- 100KFIX R. C. of Jesus Christ of L.D. Sts., Ind'p'nd'n'e, Mo.240-1250- 250KFIZ Daily C'm'nw'lth & O.A.Heulsm'n, Fond d'L'c,Wis.273-1100- 100KFJC Seattle Post Intelligencer, Seattle, Wash 270-1110- 100KFJK Delano Radio and Electric Co., Bristow, Okla 234-1280- 100KFJM University of N. Dakota, Grand Forks, N. Dak 280-1070- 100KFKB Brinkley -Jones Hospital Association, Milford, Ks 286-1050- 500KFKQ Conway Radio Laboratories, Conway, Ark 250-1340- 100KFKX Westinghouse Elec. & Mfg. Co., Hastings, Neb 341- 880-1000KFLR University of N. Mexico, Albuquerque, N. M 254-1180- 100KFLV Rev. A. T. Frykman, Rockford, Ill 229-1310- 100KFMQ University of Arkansas, Fayetteville, Ark 263-1140- 100KFMS Freimuth Dept. Store, Duluth, Minn 275-1090- 100KFMX Carleton College, Northfield, Minn 283-1060- 500KFMZ Roswell Broadcasting Club, Roswell, N. M 250-1200. 100KFNF Henry Field Seed Co. Shenandoah, Iowa 266-1130- 500KFOA The Rhodes Co., Seattle, Wash 454- 660- 500KFPT *The Deseret News, Salt Lake City, Utah 360- 833- 500KFQB *Search Light Publishing Co.. Fort Worth, Tex 254-1180- 100KFQC *Kidd Brothers Radio Shop, Taft, Cal 227-1320- 100KFQD *Chovin Supply Co., Anchorage, Alaska 280-1070- 100KFSG Echo Park Evangelistic Ass'n, Los Angeles, Cal 234-1280- 500KGN Northwestern Radio Mfg. Co., Portland, Ore 360- 833- 100KGO General Electric Co., Oakland, Cal 312- 960-1000KGU Marion A. Mulreny, Honolulu, Hawaii 360- 833- 250KGW Portland Morning Oregonian, Portland, Ore 492- 610- 500K. FTJ Times-Mirror Co., Los Angeles, Cal 395- 760- 500Kr -9 Louis Wasmer, Seattle, Wash 360- 833- 100RJR Northwest Radio Service Co., Seattle, Wash 270-1110- 100KJS Bible Institute of Los Angeles, Los Angeles, Cal 360- 833- 750KT,S Warner Brothers, Oakland, Cal 360- 833- 250KLX Tribune Publishing Co., Oakland, Cal 508- 590- 500KLZ Reynolds Radio Co., Denver, Col 360- 833- 500riNT Grays Harbor Radio Co., Aberdeen, Wash 263-1140- 250KNV Radio Supply Co., Los Angeles. Cal 254-1180- 100KNX Electric Lighting Supply Co., Los Angeles, Cal 360- 833- 100ROB N. M. C. of Agri. & Mech. Arts, State Col., N. M 360- 833- 500ROP Detroit Police Dept., Detroit, Mich 286-1050- 500RPO Hale Bros., San Francisco, Cal 422- 710- 500KQV Doubleday -Hill Electric Co., Pittsburgh, Pa 280-1070- 300RSD Post Dispatch, St. Louis, Mo 545- 550- 500KTW First Presbyterian Church, Seattle, Wash 360- 833- 750KUO Examiner Printing Co., San Francisco, Cal 360- 833- 150RUC City Dye Works & Laundry Co., L. Angeles, Cal 360- 833- 100RWG Portable Wireless Tel. Co., Stockton, Cal 360- 833- 100

W.L. K.C. W.P.

KWH Lus Angeles Examiner, Los Angeles, Cal 360- 833- 500KYQ Electric Shop, Honolulu, Hawaii 288-1040- 100KYW Westinghouse Elec. & Mig. Co., Chicago, Ill 535- 560-1000KZM Preston D. Allen, Oaklane, Cal 360- 833- 100WAAB Vaidemar Jensen, New Orleans, La 268-1120- 100WAAC Tulane University, New Orleans, La 360- 833- 100WAAF Chicago Daily, Drovers Jouinal, Chicago, Ill 286-1050- 200WAAM I R. Nelson Co., Newark, N. J 263-1140- 250WAAW Omaha Grain Exchange, Omaha, Neb 360- 833- 500WAAZ Hollister -Miller Motor Co., Emporia, Ks 360- 833- 100WABA Lake Forest College, Lake Forest, Ill 265-1130- 100WABE Young Men's Christian Assn., Washington, D. C 283-1060- 100WABI Bangor Ry. & Elec. Co., Bangor, Me 240-1250- 100WABL Conn. Agri. College, Storrs, Conn 283-1060- 100WABM F. E. Doherty Auto. & R'dio E. Co., Saginaw, M 254-1180- 100WABN Ott Radio, Inc., La Crosse, Wis 244-1230- 250WABP Robert F. Weinig, Dover, Ohio 265-1130- 100WABT Holliday -Hall, Washington, Pa 252-1190- 100WABU Victor Talking Machine Co., Carnderl, N. J 225-1330- 100WABX Henry B. Joy, Mount Clemens, Mich 270-1110- 150WBAA Purdue University, West Lafayette, Ind 360- 833- 250Wl3AD Sterling Electric Co., Minneapolis, Minn 360- 833- 100WBAH The Dayton Co., Minneapolis, Minn 416- 720- 500WBAK Penn. State Dept. of Police. Harrisburg, Pa 400- 750- 500WBAN Wireless Phone Corp., Paterson, N. J 244-1230- 100WBAP Wortham-Carter Pub. Co., Fort Worth, Tex 476- 630- 750WBAV Erner & Hopkins Co., Columbus, Ohio 389- 770- SOOWBAW Marietta College, Marietta, Ohio 246-1220- 250WBAY American Tel. & Tel. Co., New York, N. Y 492- 610- 500WBBF Georgia School of Technology, Atlanta, Ga 270-1110- 500WBBG *Irving Vermilya, Mattapoisett, Mass 248-1210- 500WBBM Frank Atlass Produce Co., Lincoln, Ill 255-1330- 200WBBO Michigan Limestone & Chem. Co., Rodgers, Mich 250-1200- 500WBBQ Frank Crook, Pawtucket, R. I 252-1190- 100WBBR *Peoples' Pulpit Ass'n, Rossville, N. Y 273-1100- 500WBR Penn State Police, Butler, Pa 286-1050- 250WBT Southern Radio Corp., Charlotte, N. C 360- 833- SOOWWI, City of Chicago, Chicago, Ill 286-1050- 500WBZ Westinghouse Elec. & Mfg. Co., Springfield, Mass 337- 890-1000WCAD St. Lawrence University, Canton, N. Y 280-1070- 250WCAE Kaufmann & Baer Co., Pittsburgh, Pa 461- 650- 500WCAH Entrekin Electric Co., Columbus, 0 286-1050- 100WCAJ Nebraska Wesleyan Univ., Univ. Place, Neb 360- 833- 500WCAL St. Olaf College, Northfield, Minn 360- 833- 500WCAM Villanova College, Villanova, Pa 360- 833- 150WCAI5 Chesapeake & Potomac Tel. Co., Wash'gt'n, D. C 469- 640- 500WCAR Alamo Radio Elec. Co., San Antonio, Texas 360- 833- 100WCAS W. H. Dunwoody Ind. Inst., Minneapolis, Minn 246-1220- 100WCAT S. Dakota State Sch. of Mines, Rapid City, S. D 240-1250- 100WCAU *Durham & Co., Philadelphia, Pa 286-1050- 250WCAY Kerselman-O'Driscoll Co., Milwaukee, Wis 261-1150- 250WCBC Univ. of Michigan, Ann Arbor, Mich 280-1070- 200WCBD Wilbur G. Voliva, Zion, Ill 345- 870- 500WCR Stix, Baer & Fuller Dry Goods Co.. St. Louis, Mo 360- 833- 100WCM University of Texas, Austin, Tex , .360- 833- 500WCX Detroit Free Press, Detroit, Mich 517- 580- 500WDAE Tampa Daily Times, Tampa, Fla 360- 833- 250WDAF Kansas City Star, Kansas City, Mo 411- 730- 500WDAG T. Laurance Martin. Amarillo, Tex 263-1140- 100WDAH Trinity Methodist Church. El Paso, Texas 268-1120- 100WDAK The Courant, Hartford, Conn 261-1150- 100WDAP *Drake Hotel (Whitestone Co.), Chicago, Ill 360- 833-1000WDAR Lit Brothers, Philadelphia, Pa 395- 760- 500WDAU Slocum & Kilburn. New Bedford, Mass 360- 833- 100WDAX First National Bank, Centerville, Iowa 360- 833- 100WDBH *Worcester, Mass. 268-1120- 100WDBK *M. F. Bros. F., H. & Radio Co., Cleveland, 0_248-1210- 1C0WDBR *Tremont Temple Baptist Church. Boston, Mass 256-1170. 100WEAF American Tel & Tel. Co.. New York, N. Y 492- 610- SOOWEAH Wichita Board of Trade, Wichita, Ras 280-1070- 100WEAI Cornell University, Ithaca, N. Y 286-1050- 500WEAJ University of S. Dakota, Verinillion. S. Dak 283-1060- 200WEAM *Borough of N. Plainfield, N. Plainfield, N. J 286-1050- 150WEAN Shepard Co.. Providence, R. I 273-1100- 100WEAO Ohio State University, Columbus, Ohio 360- 833- 500WEAP Mobile Radio Co., Mobile, Ala 360- 833- 100WEAS Hecht Co., Washington, D. C 360- 833- 100WEAU Davidson Bros. Co. Sioux City, Iowa 360- 833- 100WEAY Iris Theatre, Houston, Texas 360- 833- 500WEB *Benwood Co., St. Louis, Mo 273-1100- 500WEBH *Eclgewood Beach Hotel Co., Chicago, Ill ..-....-....WEV Hurlburt-Still Electric Co., Houston, Texas 360- 833- 100WEW St Louis University, St. Louis, Mo 280-1070- 100WFAA Dallas News & Dallas Journal, Dallas, Tex 476- 630- 500WFAB Carl F. Woese, Syracuse, N. Y 234-1280- 100WFAH Electric Supply Co., Port Arthur, Tex 236-1270- 150WFAN Hutchinson Elec. Service Co., Hutchinson, Minn 360- 833- 100WFAV Univ. of Nebraska, Dept. of E. Eng., Lincoln, Neb.275-1090- 500WFBW *Ainsworth -Gates Radio Co., Cincinnati, Ohio 309- 970- 750WFI Strawbridge & Clothier, Philadelphia, Pa 395- 760- 500WGAO Glenwood Radio Corp., Shreveport, La 360- 833- 100WGAW Ernest C. Albright, Altoona, Pa 261-1150- 100WGAV Northwestern Radio Co., Madison, Wis 360- 833- 100WG4Z South Bend Tribune, South Bend, Ind 360- 833. 250WGI Ant. R'dio & Res'ch Corp., Medf'd Hillside, Mass 360- 833- 100WGL Thomas F. J. Rowlett, Philadelphia, Pa 360. 833- 250


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W.L. B.C. W.P.WGR Federal Tel. & Tele. Co., Buffalo, N. Y 319- 940- 750WGV Interstate Electric Co., New Orleans, La 242-1240- 100WGY General Electric Co., Schenectady, N. Y 380- 790-1000WHA University of Wisconsin, Madison, Wis 360- 833- 500WHAA State University of Iowa. Iowa City, Iowa 484- 620- 500WHAB Clark W. Thompson, Galveston, Tex 360- 833- 200WHAD Marquette University, Milwaukee, Wis 280-1070- 100

-WHAG University of Cincinnati, Ohio 222-1350 200WHAH Rafer Supply Co., Joplin, Mo 283-1060- 250WHAM University of Rochester, Rochester, N. Y 283-1060- 100WHAS Courier -Journal & Louisville Times, Louisville, Ky 400- 750- 500WHAZ Rensselaer Polytechnic Institute, Troy, N. Y 380- 790- 500WHB Sweeney School Co., Kansas City, Mo 411- 730- 500WHK Radiovex Co., Cleveland, Ohio 283-1060- 100WHN George Schubel, New York, N. Y 360- 833- 100WHO *Des Moines, Ia. 526- 570- 500WIAC Galveston Tribune, Galveston, Tex 360- 833- 100WIAD Howard R. Miller, Philadelphia, Pa 254-1180- 100WIAJ Fox River Valley Radio Supply Co., Neenah, Wis 224-1340- 100WIAK *Journal -Stockman Co., Omaha, Neb 278-1080- 250WIAO *School of Eng. of Milwaukee, Milwaukee, Wis 246-1220- 100WIAR Paducah Evening Sun, Paducah, Ky 360- 833- 100WIAS Home Electric Co., Burlington, Iowa..., . 360- 833- 100WIK K. & L. Electric Co., McKeesport, Pa 234-1280- 100WIP Gimbel Brothers, Philadelphia, Pa 508- 590- 500WJAB *American Electric Co., Lincoln, Neb 229-1310- 100WJAD Jackson's Radio Eng. Laboratories, Waco, Tex 360- 833- 150WJAG Norfolk Daily News, Norfolk, Neb 283-1060- 250WJAN Peoria Star, Peoria, III 280-1070- 100WJAQ Capper Publications, Topeka, Ks 360- 833- 100WJAR The Outlet Co., Providence, R. I 360- 833- 500WJAS Pittsburgh Radio Supply House, Pittsburgh, Pa 250-1200. 500WJAX Union Trust Co., Cleveland, Ohio 390- 770- 500WJH Wrn. P. Boyer Co., Washington, D. C 273-1100- 100WJX Deforest Radio Tel. & Tel. Co., N. Y., N. Y 360- 833- SOOWJY R. C. A., New York, N. Y 405- 740- 500WJZ Broadcast Central, New York, N. Y 454- 660- 500WKAA H. F. Paar, Cedar Rapids, Iowa 268-1120- 100WKAF W. S. Radio Supply Co., Wichita Falls, Tex 360- 833- 100WKAP Dutee W. Flint, Cranston, R. I 360- 833- 250WKAQ Radio Corp. of Porto Rico, San Juan, P. It 360- 833- 500WKAR Michigan Agr. College, E. Lansing, Mich 280-1070- 500WRBF *D. W. Flint, Providence, R. I 286- - 5001VKY *WKY Rodin Shoo. Oklahoma, Okla 360- 833- 100WLAG Cutting & Wash. Radio Corp., Minneapolis, Minn 416- 720- SOOWLAH Samuel Woodworth, Syracuse, N. Y 234-1280- 100WLAJ Waco Electrical Supply Co.. Waco. Tex 360- 833- 150WLAK Vermont Farm Machine Corp., Bellows Falls, Vt...360- 833- SOOWLAL Naylor Electrical Co., Tulsa. Okla ' 360- 833- 100WLAN Putnam Hardware Co., Houlton, Me 283-1060- 250WLAW Police Dept. City of N. Y., New York. N. V 360- 833- 500wT,nT. *win -0, -,sin Dent, of Markets. Stevens Pt., Wis. . 278-1040- 500WLW Crosley Mfg. Co., Cincinnati. 0 309- 970. 500WITAB Radio Slimily Co.. Oklahoma, Okla 360- 833- 100WMAC Clive B. Meredith. Cazenovia, N. Y . 261-1150- 200WMAF Round Hills Radio Corp., Dartmouth, Mass 360- 833- 500

r,,:-F-ral Sunolv Co., Lincoln. Neb 254-1140- 100WMAJ Drovers Telegram Co., Kansas City, Mo 275-1090- 250

II

W.L. K.C. W.P.WMAK *Lockport, N. Y 273-1100- 500WMAQ Chicago Daily News, Chicago, Ill 448- 670- 500WMAT Paramount Radio Corp., Duluth, Minn 266-1130- 250WMAV *Alabama Polytechnic Institute, Auburn, Ala 250-1200- 500WMAY Kingshighway Presbyterian Church, St. Louis, Mo 280-1070- 100WMAZ *Mercer University, Macon, Ga 261-1150- 100WMC "Commercial Appeal," Memphis, Tenn 500. 600- 500WMU Doubleday -Hill Elec. Co., Washington, D. C 261-1150- 100WNAC Shepard Stores, Boston, Mass 278-1080- 100WNAD University of Oklahoma, Norman, Okla 360- 833- 100WNAN Syracuse Radio Telephone Co., Syracuse, N. Y 286-1050- 200WNAP Wittenberg College, Springfield, Ohio 231-1300- 100WNAS Tex. Radio Corp. & Austin Statesman, Austin, Tex.360- 833- 100WNAT Lenning Brothers Co., Philadelphia, Pa 360- 833- 250WNAV People's Tel. & Tel. Co., Knoxville, Tenn 236-1270- 500WNAX Dakota Radio Apparatus Co., Yankton, S. D 244-1230- 100WOAC Pagan Organ Co., Lima, Ohio 265-1130- 150WOAG Apollo Theatre, Belvidere, Ill 273-1100- 100WOAH Palmetto Radio Corp. Charleston, S. C 360- 833- 100WOAI Southern Equipment Co., San Antonio, Tea 384- 780- 500WOAL William E. Woods, Webster Groves, Mo 229-1310- 100WOAN Vaughn C'nserv't'ry of Music, Lawrenceb'rg, Tenn 360- 833- 200WOAP Kalamazoo College, Kalamazoo, Mich 283-1160- 100WOAV Penn. Nat'l Guard, 2d Bat, 112th Inf., Erie, Pa 242-I240- 100WOAW Woodmen of the World, Omaha, Neb 526- 570- 500WOAX Franklyn J. Wolff, Trenton, N. J 240-1250- 500WOC Palmer Sch. of Chiropractic, Davenport, Iowa 484- 620- 500WOI Iowa State College, Ames, Iowa 360- 833- 500WOK Pine Bluff Co., Pine Bluff, ArkWOO John Wanamaker, Philadelphia, PaWOQ Western Radio Co., Kansas City, MoWOR L. Bamberger & Co., Newark, N. JWOS Mo. State Marketing Bureau, Jefferson City, MoWPAB Pennsylvania State College, State College, PaWPAC Donaldson Radio Co., Okmulgee, OklaWPAH Wisconsin Dept. of Markets, Waupaca, WisWPAJ *New Haven, ConnWPAK North Dakota Agri. Col., Agri. College, N. DWPAL *Avery & Loeb Elec. Co., Columbus, OhioWPAM Auerbach & Geutell, Topeka, KasWPAZ John R. Koch (Dr.), Charleston, W. VaWQAA Horace A. Beale, Jr., Parkesburg, PaWQAC E. B. Gish, Amarillo, TexWQAM Electrical Equipment Co., Miami, FlaWQAN Scranton Times, Scranton, PaWQAO Calvary Baptist Church, New York. N. YWQAQ Abilene Daily Reporter, Abilene, TexWQAS Prince -Walter Co., Lowell, MassWQAX Radio Equipment Co., Peoria, IllWOJ *Calumet Baking Powder Co., Chicago, IllWRAA Rice Institute, Houston, TexWRBC *Immanuel Lutheran Church, Valparaiso. IndWRK Doren Bros. Electric Co., Hamilton, OhioWRAL No. States Power Co., St. Croix Falls, WisWRAM Lombard College, Galesburg, IllWRAV Antioch College, Yellow Springs, OhioWRAX Flexon's Garage, Gloucester City, N. JWRAY Radio Sales Corp., Scranton, PaWRC Radio Corp. of America, Washington, D. CWRK Doren Bros. Electric Co., Hamilton, OhioWRL Union College, Schenectady, N. YWRM University of Illinois, Urbana. IllWRW Tarrytown Radio Research Lab., Tarrytown, N. YWSAB S. E. Mo. State T'chers' Col., Cape Giradeau, Mo.WSAC Clemson Agri. Col., Clemson College, S. CWSAD J. A. Foster Co.. Providence, R. I\VSAH A. G. Leonard, Jr., Chicago, IllWSAI U. S. Playing Card Co., Cincinnati OhioWSAJ Grove City College, Grove City, PaWSAR *Doughty & Welch Elec. Co., Fall River. MassWSAP Seventh Day Adventist Church, New York, N. YWSAV *Clifford W. Vick Radio Const. Co., Houston, TexWSAW Curtis & McElwee. Canandaigua, N. YWSAX *Chicago Radio Laboratory, Chicago, IllWSAY Irving Austin, Port Chester, N. YWSB Atlanta Journal, Atlanta, GaWSL J. & M. Electric Co., Utica, N. YWSY Alabama Power Co., Birmingham, AlaWTAB *Fall River Daily Herald, Fall River, MassWTAC *Johnstown, PaWTAM The Willard Storage Battery Co., Cleveland, 0WTAN Orndorff Radio Shop, Mattoon, IllWTAQ S. H. Van Gorden & Son, Osseo, WisWTAR Reliance Electric Co.. Norfolk, VaWTAS Charles E. Erbstein, Elgin, Ill., nearWTAT Edison Electric Ilium. Co., Boston, MassWTAW *Co'lege Station, TexasWTAY *Oak Leaves Broadcasting Station, Oak Park, Ill 283-1330- 500WTG Kansas State Agri. Col., Manhattan Ks 360- 833- 500WWAD Wright & Wright, Inc., Philadelphia, Pa 360- 833- 500WWAE Alamo Dance Hall, Joliet, III 227-1320- 500WWAF Galvin Radio Supply Co., Camden, N. J 236-1270- 100WWAO Michigan College of Mines, Houghton, Mich 244-1230- 250WWJ Detroit News. Detroit, Mich 517- 580. 500WVVL Loyola University, New Orleans, La 268-1120- 100

* Alterations and additions.

265-1130- 250508- 590- 500360- 833- 500405- 740- 50(1

.441- 680- 500283-1060- 500360- 333- 200360- 833- 500268-1120- 100360- 833- 250286-1050- 500360- 833- 100273-1100- 100360- 833- 500234-1280- 100283-1060- 100280-1070- 100360- 633- 100360- 333- 100265-1130- 100360- 833- 100448- 670- 500360- 833- 200278-1080- 500360- 833- 200248-121')- 100244-I230- 250242-1240 100268-112(- 100280-1070- 100469- 640- 500360- 833- 200360- 833- 500360- 833- 500

.273-1100- 150

.360- 833- 100360- 833- 500261-1150- 150248-1210- 500309- 970- 500360. 833- 250.254..-....-...263-1140- 250.360- 833- 100275-1190- 100448- 670-1000232-1290- 100428- 700- 500273-1100- 100360- 833- 500248. - -

275-1090- 150.389- 770-1000

240-1250- 100225-1330- 100280-1070- 100286-1050- 500246-1220- 100280-1070- 250

For Summertime Radio by RoadsideStream or Rolling Surf-

Here are the makings for as fine a little portable set asyou will see anywhere this summer. A set you will showwith pride and your friends will listen to with real enjoy-ment. Furthermore, it can be made really portable, justabout camera size. If you can't do the work yourself, letyour radio friend do it for you.

A Coto Compact Portable Set is Easily built.

Two tubes give Loud Speaker Volume on

near Stations. Excellent D. X. on Phones

Superior Audio Amplifi-cation for the

Coto Portable SetThe writer of this advertise-

ment listened last night toChauve Souris from Boston viaWEAN. Two tubes and TableTalker, fine volume and splen-did tone. Never heard betterreception on any set. That isthe kind of radio this 5 to 1

ratio transformer gives everytime.

Type 4000 . . $5.00

0ec).

Don't attemptto substituteparts if youwant best re-sults. Enclosecoupon andmoney orderwith letter giv-ing dealer'sname.

ret4045

AUDIO fREQUENO

nwaoisft.

And a Real Compact Variocouplerin Polished Brown Bakelite

The compactness of the Coto Air Condenser andthis popular variocoupler enables you to build yourset on panel 5 x 10 or even 4 x 8 inches. Size ofvariocoupler is only 31/4 x 3 x 3% inches, yet itoperates perfectly over the whole broadcastingband of wavelengths. Mounts either on base orpaneL

di)

o,tp

We will ship through himthe same day your orderis received.

9000. $5.50Type

4/0 Coto -Coil Co87 Willard Avenue

Providence, R. I.

Sq

Co

..11111111t4L;

.'11

Volume, Sharp Tuningand Lasting

EfficiencyThe electrical characteristics

of this SILVER PLATED Con-denser with Vernier are reallyremarkable. For the .0005 Mfd.Condenser, maximum capacityis .000540, minimum capacity.0000240, power factor .00063.Even if you do not understandthe significance of these figures,the tuning of your Coto set willtell you.

Type 3505.0005 Mfd $5.00

Other capacities are .001 Mfd.$0, and .00025 Mfd. $4.50.

G I LIRADIO APPARATUS

The Giblin Broadcast ReceiverTEIE Giblin Radio Frequency Broadcast

Receiver makes it possible to obtainradio entertainment without the necessityof erecting outside antenna wires or usinga troublesome ground wire. A small, loopaerial placed near the set will pick up sig-nals, which, though they have come longdistances, and are weakened by hills, val-leys, trees and buildings, will be clear andof great volume. Many families, living inapartments where it is undesirable or im-possible to erect antenna wires, can nowhear enjoyable, ever-changing programsthrough the day and evening by "listening -in" with a Giblin Radio Frequency Broad-cast Receiver.

The Giblin Audio -FrequencyAmplifying Transformer

Price $4.50

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DETECTOR "A4WITCHAMPLIFIER

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The set comprises two stages of radio frequency ampli-fication, a detector and 'three stages of audio frequencyamplification. The parts are mounted on a sub -base towhich a Bakelite panel is attached. It is enclosed in ahandsome solid mahogany cabinet.

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The Giblin Radio -FrequencyAmplifying Transformer

Price $5.00

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STANDARD ]RADIO &ELECTRIC CO.PAW TUCKE T. RHODE ISLAND

av§w eg16 - americanradiohistory.com · replaces the vernier, as it can be moved forward or...

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