RADIO BROADCAST ARTHUR H. LYNCH, Editor 1925 WILLIS K. WING, Associate Editor DECEMBER, JOHN B. BRENNAN, Technical Editor Vol. VIII, No. 2

BEHIND THE EDITORIAL SCENES

- new and enlarged RADIO BROADCAST has met with almost Cover From a Painting by Fred J. Edgars Design THEuniversal favor and its reception was even more hearty than the had dared In New York the Radio Enters the Club - publishers hope. City alone, Frontispiece supply of the November number was exhausted four days after How Radio Grew Robert H. Marriott 159 it was placed on sale. Copies of the number are so rare that we Up haven't more than three copies in the editorial offices for our own use. Letters from readers all over the have been most Tubes: Their Uses and Abuses - - Keith Henney 163 * country generous in praising the appearance and contents of the November - - - - number. The March of Radio J- H- Morecro/t 167 H. MARRIOTT, whose article, "How Radio A Five'Tube Receiver of Dual Efficiency ROBERTGrew Up" leads this issue, is one of the old men of wireless Glenn H. Browning 172 in the United States. He was the first president of the Insti- tute of Radio Engineers, was one of the first radio inspectors to be The Listeners' Point of View Kingsley Welles 177 appointed after the radio law of 1912 was passed. For a long time he was expert radio aide at the Bremerton Navy Yard, Short Waves A New Paradise for the DX Fan Washington, and is now a consulting radio engineer in New

York. . . . who writes about short in Edgar H. Felix 182 Edgar Felix, waves this number, was for several years publicity representative of Plans for the Third of the International Radio Broad' station WEAF in New York. Glenn H. Browning, who with his inseparable technical partner, Mr. F. H. Drake, has become cast Tests **.** Arthur H. Lynch 185 nationally known for the Browning-Drake receiver, describes a great improvement over the early model in this number. Both Plate Current Unit An Improved Supply Mr. Browning and Mr. Drake are familiar figures around the Roland F. Beers 186 famous Cruft laboratory at Harvard University, where much of their work has been done. The valuable current periodical As the Broadcaster Sees It - - - - Carl Dreher 191 surveys, made by E. G. Shalkhauser, the first of which appeared in our November issue, are continued in this number. Many The "Aristocrat" Receiver: Resistance'Coupled readers have written us saying that these condensed surveys of the articles in this and in our '*..*' - 196 important appearing magazine Amplification contemporaries are of great value to them. in Receiver How to Use Meters Your James Millen 198 January RADIO BROADCAST will contain an article by THEArthur H. Lynch telling how to build "RADIO BROADCAST'S New Fields For the Home Constructor Universal Receiver." The set he describes is an unusual and Keith Henney 201 very efficient combination of standard parts and it is doubtful if there is any receiver its superior in point of sensitivity and "Now, I Have Found" 206 quality. It is not a "freak" outfit in any sense. Kendall of will have an article about the of Tracing Radio Noises Clough Chicago principles A Ratchet Coil Winder audio amplification which is of particular interest. The author for the Roberts Circuit A Coupling Device weighs and casts aside some of the commonly accepted theories A File for Ideas of amplification. We believe the article will attract a deal Super-He'erodyne Noises great of attention. Wallace Checkii t* up on B-Battery Leakage Mr. John of Evanston, Illinois, will from A Vark meter for the Roberts Set now on write the "Listeners' Point of View." With his central Mr. Wallace is able to hear broadcast How to Eliminate Local Interference - - 212 location, offerings in almost every part of the United States and Canada. Our new broadcast critic is an versatile for he is a writer A List of Australian Stations 224 unusually person, Broadcasting of great charm and not a little wit. as well as an artist of consider- able In his his and humorous The Grid and Answers - - 226 ability. college days, drawings Questions "pieces" appeared in the Cornell Widow. Coil Placement in an R. F. Amplifier Precautions in Antenna Erection r ( T" HE advertising pages of the magazines of the "Quality Measuring the Resistance of Coil Units JL Matching Tubes and R. F. Coils Group," that is, the Atlantic Monthly, Harpers, Review of Reviews, Scribners, and the World's Worf; now contain only the A Key to Recent Radio Articles E. G. Shalkhauser 232 announcements of those radio manufacturers whose products have been tested and approved by the Laboratory of RADIO - - - Is Your Set a Blooper? 238 BROADCAST. Readers of those magazines who are not well versed in matters radio have the privilege of calling on the technical What Our Readers Write Us 244 staff of this magazine for help and advice.

Doubleday, Page Sr Co. Doubltday, Page fir Co. BOOK SHOPS Doubleday, Page & Co. Doubleday, Page & Co. MAGAZINES TAYLOR BOOK OFFICES OFFICERS ("LORD & SHOP COUNTRY LIFE I PENNSYLVANIA TERMINAL GARDEN CITY, N. Y. NEW YORK: (2 Shops) F. N. DOUBLEDAY. President WORLD'S WORK I 38 WALL ST. NEW YORK: 120 WEST 32ND STREET GARDEN & HOME BUILDER (.GRAND CENTRAL TERMINAL A. W. PAGE, Vice-President RADIO BROADCAST NORTH STH STREET BOSTON: PARK SQUARE BUILDING ST. Louis: NELSON DOUBLEDAY, Vice-President SHORT STORIES [2234914 MARYLAND AVENUE CHICAGO: PEOPLES GAS BUILDING EDUCATIONAL REVIEW GRAND AVENUE RUSSELL DOUBLEDAY, KANSASAS CITY,rrrv t 920 SANTA BARBARA, CAL. Secretary LE PETIT JOURNAL j Jo6 WFST 4?TH STREET A. Treasurer EL Eco TOLEDO: LASALLE & KOCH LONDON: WM. HEINEMANN LTD. S. EVERITT, THE FRONTIER CLEVELAND: HIGBEE Co. TORONTO: OXFORD UNIVERSITY PRESS JOHN J. HESSIAN, Asst. Treasurer

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Copyright, 1925, in the United States, 'Newfoundland, Great Britain, Canada, and other countries by Doubleday, Page & Company. AH rights reserved. TERMS: $4.00 a year; single copies 35 cents.

'54 RADIO BROADCAST ADVERTISER 157

// **> V.VG

. oa in

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1925 Jewett Radio & Phonograph Co

Tested and approved by RADIO BROADCAST RADIO ENTERS THE CLUB

The installation at the Cornel! Club in 'Nfw Tor); City. The Western Electric super-heterodyne tfith peanut tubes is shown in the the top view at the left. A four-tube amplifier below intensifies the energy which is supplied to the loud speakers on panelled uialls of the various rooms. Employees of the Club are shown listening to the first test of the equipment. A public address system is also installed. Microphones picf( up the speeches mhich are carried to all parts of the club through the loud speakers RADIO BROADCAST

VOLUME VIII NUMBER 2

DECEMBER, 1925

Grew Up

Many Little Known Facts About Radio Development are Related Here Is the First of a Series of Articles on This Subject Written by a Pioneer in Wireless By ROBERT H. MARRIOTT First President Institute of Radio Engineers

EPEATEDLY during the last one ers have received little compensation for pay. Some of those people need the money, hundred years, radio has been their work in the past and they are not in others do not; some are dead while those referred to as new, which has a position to collect now. The public still alive do not expect to realize anything had the result of making people owes a debt to many people which it cannot on their past labors. come to the conclusion that it must be new. The changes in radio development may This is, of course, very confusing, and is often be traced to unexpected causes. due no doubt to the fact that certain in- For example, the United States Prohibition ventions and inventors have been overrated Act seems to have played a somewhat while others have been forgotten. Human important role in the recent stimulation love of fairy tales makes it easy for a of radio broadcasting. Volstead's man or a corporation with money to unintentional creation of laborious refer to a certain individual as the home brewing and the attendant great one who has done all of the* substitution of inconvenient boot- wonderful things that have been leggers for bar tenders, has appar- done. Money getters, too, take ad- ently been an important step in the vantage of that love of fairy stories development of radio, because it to fill their pockets. suddenly has shut off from the public Haywire, halos, and haymakers a very convenient means of spending have characterized many of the early their money. Now these baffled careers in radio. Inventors and people are looking for other outlets. would-be inventors built haywire Broadcast receiving has supplied apparatus. Promoters built press that demand, and its problems pres- agent halos around the alleged in- ent a new field in which alcohol-free ventors and their haywire products. brains may engage. Some of the hay went to develop Not only is radio history valuable radio and a lot of it went to whoever as a thing of interest, as educational, received the stock jobber's money. and as a precedent for use in plan- Sometimes promotors became so ex- ning the future, but it is valuable in travagant in the claims about an other ways. I was recently examined invention that the inventor himself and cross-examined for three days would be found to disclaim some of about historical radio devices, for the things that he was purported to evidence in a radio suit. I believe have done, and to give the credit to the suit was for several millions of others. Such a procedure was, of dollars. At any rate the amount was course, just what the promoters so interesting that two lawyers and wanted, and they immediately got an expert traveled across the United their press agents and after-dinner States and back to get my testimony. A PORTABLE SET, IQOI MODEL speakers on the job, in order that The lawyers' questions and my Mr. Marriott operating a portable transmitting set. Note they might tell how modest and answers in that took gen- the ground plate on the floor. With an outfit about the same testimony up erous 1 in the inventor was, and thereby size as this, using vacuum tubes as the radio generating device, more words than am using this tremendous stud his halo with the pearls of signals are being sent by amateurs using code, for whole series of articles. The testi- distances. The Laboratory of RADIO BROADCAST recently modesty and generosity. mony was relative to only a few communicated with the U. S. S. Seattle as she was leaving is due to rather historical devices which had their Homage many Tahiti in the Pacific ocean. A five-watt tube was used as a than to a few. Many radio develop- transmitter for this remarkable communication origin from 1899 on, while I am striv- 160 RADIO BROADCAST DECEMBER, 1925

U.S. RADIO DEVELOPMENT CHART DECEMBER, 1925 HOW RADIO GREW UP 161 which, in attempting to obtain a monopoly, set out to ad- vertise to everybody that Marconi was the inventor and that they owned that patent on wireless which entitled them to a monopoly in America and other places. That was not, of course, true, but he did advertise wireless and to him is due the credit for having started the development of radio in many different parts of the world. By 1900 radio had edged itself into the market as a mild public service. It continued as a tonic and stimulant for business, for military purposes, and for life saving. To obtain plenty of radio equipment for recent war pur- poses greater quantities of money and effort were sud- denly put forth. In 1921 a radio by-product called broad- casting began to take on. Now it is a principal product, a product that sold for about $3 50,000,000.00 last year. That is a very brief outline of some of the more important events in the history of radio. Luigi Galvani was an Italian anatomist and he got the kicks from frogs' legs when he put them near an electric INTER.IOR OF THE OLD ANNAPOLIS STATION spark. Nowadays we would call his spark maker a radio transmitter while the detached frogs' legs acted as the radio detector. Therefore he must be credited with having ing another wire from the have been wireless, but not radio. He made a genuine radio experiment one hundred and thirty- sea shore to the electrified specified for the flow of a direct current five years ago. The distance between the spark gap and spot at Mallorca, the com- from one station to the other, rather than legs must have been only a few inches or, at most, a few munication between the two waves composed of combined magnetic are feet, and at that time the whys and wherefores probably charged surfaces would be fields and condenser fields such as were not realized. complete, for the electric radiated from one radio station to another. On December 16, 1795, De Salva, a Spanish physicist, fluid would traverse the sea, However he had the idea of establishing read a paper before the Academy of Sciences at Barcelona which is an excellent con- wireless communication. Therefore the in which he said: "One could, for example, arrange at ductor, and indicate by the idea of wireless communication by elec- Mallorca an area of earth charged with electricity, and at spark the desired signal." trical means must be at least one hundred Alicante a similar space charged with opposite electricity, If Salva's scheme had and thirty years old. with a wire going to, and dipping into, the sea. On lead- worked as he said, it would In 1831, Faraday demonstrated electro-

A GALLERY OF TRANSMITTING APPARATUS

In use between 1899 ar>d '9' 5 set up in the Brooklyn Navy Yard. Mr. Marriott, at the left in the photograph, was the expert witness in a case tried before a United States judge in 1915. In the foreground, to the right, is a ten-inch induction coil, with separate vibrator. This was connected directly to the antenna and was popular until about 1906. Various kinds of glass jar transmitting condensers can be seen. The inductances, of large wire, are "oscillation transformers" and coupled the oscillating circuit, consisting of spark gap and condenser, inductively to the secondary circuit which had taps leading to antenna and ground. This is a most unusual historical photograph 162 RADIO BROADCAST DECEMBER, 1925

magnetic induction. He showed that Stating the Loomis claim briefly and in large circle around him and his receiving making current start and stop in one cir- present day language; if you put up an apparatus. Weather scientists may find cuit would cause currents to flow in a cir- antenna where it will get atmospheric this suggestion useful. cuit parallel to it, although there be no charges, and interrupt the flow of current From observations made with this kind connecting wires between the two circuits. from the antenna to ground, you can of an arrangement, it seems that some of That was a kind of wireless, but it is not send messages. If the atmospheric vol- the interference one hears on a broadcast classed as the kind of wireless we call tage is high enough so that the sparks receiver is probably due to the atmosphere radio. from antenna to ground will jump a gap charging insulated conductors to such a Professor Samuel F. B. Morse, of the of one inch, it would be possible to send high voltage that the charge jumps over United States, telegraphed across narrow messages more than a hundred miles to earth in one spark which produces bodies of water in 1842, by installing a to a present day receiver. However, a click, or many sparks, that produce ground return transmitter circuit along the atmospheric voltage is not reliable grinding, buzzing, or sizzling noises. The one bank and a ground return receiver cir- for telegraphing, because conditions vary conductor in question might be a guy wire, cuit along the other, without any wires widely in different locations and at different fence wire, power wire, or something else. between the sender and receiver. His, times. Unless you use a sensitive galvan- If electric power follows those pilot sparks again, was not radio communication but ometer you might be unable to detect any to earth, you may hear an alternating it was wireless communication. He not voltage on your antenna, the day you read current or commutator hum. Falling rain only had the idea of communicating this. On the other hand, it is not a safe may contribute both voltage and moisture, without using wires between the trans- thing to try, carelessly, because you might causing a power circuit to leak over in- mitter and receiver, but he did actually get too much voltage, especially just before sulators. telegraph with success that way. The a rain storm. I am not an inveterate story reader, but currents between the points at which That arrangement as described by so far as I know, fiction writers have he connected his transmitter are sup- Loomis, has worked for me many times overlooked the possibilities of the Loomis posed to have wandered across the stream in years past and in fact I am experimenting antenna. All their hero or heroine needs and through the wire that connected the with such a device at present. I am using for wireless salvation are the right weather two points of ground or water contact of the system to find out things about the conditions, an elevated conductor and the his receiver. That was a kind of wireless unidentified noises that interfere with radio code. The villain might even grab that worked, and it worked more than radio receiving, and about fading and the conductor and get a static knock-out. eighty years ago. static. The one I am working with now Loomis was away ahead of his time. His The electromagnetic theory, which is is interrupted by a little copper water patent was not only for communicating our present accepted theory of radio wheel. When the voltage is low the without wires, but for taking the electricity wave propagation, is said to have origin- current only discharges from the antenna to do it with from the atmosphere. He ated with William Clerk Maxwell, a noted through the longest paddle of the wheel. apparently did not reason according to the Scotch physicist in about 1867, and it was When the voltage is high it jumps to all radio theory, but the idea he patented published shortly after that time. four. Some of us can hear it click at our certainly works that way. He wanted to receiving stations and get an idea of what make static send messages. He probably LOOMIS UTILIZES STATIC FOR SENDING is happening in the atmosphere. imagined wonderful possibilities "via 3Oth, 1872, patent number 129,971, An observer might record the area static," but I daresay he didn't go so far as JULYwas issued to Mahlon Loomis, dentist, and movement of high to imagine then that the new baby of Washington, District of Columbia. voltage atmosphere by across the street was destined to The following is quoted from the patent. setting up numerous make money from automobiles; move Loomis antennas, with (he might even fly) to Southern' What I claim as my invention or discovery, clock operated spark California to a called Los and desire to secure by Letters Patent, is place and The utilization of natural electricity from gaps having differently Angeles there buy a winter home elevated points by connecting the opposite timed interruptions, in a for a fabulous sum, of the celestial and terrestrial bodies polarity retire and spend his of electricity at different points by suitable time playing Mah conductors, and, for telegraphic purposes, relying upon the disturbance produced in the Jongg or working two electro-opposite bodies (of the earth and cross word puzzles, atmosphere) by an interruption of the continuity and maybe even of one of the conductors from the electrical drinking home brew body being indicated upon its opposite or corres- while to ponding terminus, and thus producing a circuit listening or communication between the two without Washington jazz an artificial battery or further use of wires delivered without or cable to connect the cooperating stations. "wires," in 1925.

HIGH POWERED EQUIPMENT IN 1903 The ten-inch induction coil which was standard during the early years of wireless as the trans- mitter. Nothing was simpler than the circuit used. About twenty volts was supplied to the primary of the coil and some eighty or a hundred thousand volts were produced between the electrodes the operator is adjusting. Ships and shore stations alike used the coils and sharp tuning was unknown. Those were the days when no one knew exactly what wavelength he was using and didn't care. The few wavemeters in existence were objects of curiosity in almost inaccessible laboratories FIG. I to occurs. A collection of modern tubes, nearly all of which are designed for the second audio stage where so much distortion due overloading now and small The power tubes illustrated in this photograph are Western Electric 2i6-A, ux-i 12, ux-2io, ux-iao, uv-2O2, Cleartron, Heliotron. The the Daven "peanut" tube is the Western Electric "N" tube, and in the photograph are two tubes designed for resistance-coupled amplifiers, "MU-2O" and the High Constron. Daven also makes a power tube known as the Daven "MU-6."

Tubes: Their Uses and Abuses

How to Use the Standard and the Latest Tubes to Attain High Quality in the Radio Receiver Some Little Known But Easily Applied Facts of Increasing Importance About Audio Amplification

" KEITH HENNEY < By ; Director, "Radio Broadcast" Laboratory

E of the vacuum tube If a tube know that its char- ditions under which they must be operated to get development you buy 5-volt you has placed in the hands of engineers and acteristics will be such and such within fairly nar- best results. It is the purpose of this article scientists and radio listeners one of row limits. This means that you can interchange to deal with those best operating conditions and the most versatile and useful devices tubes with out "spilling the beans." Some manu- to attempt to point out a few noteworthy ideas that has resulted from man's ingenuity. The facturers of tubes take particular precautions to in the design of radio receiving equipment that central applications of the vacuum tube device are so have their tubes all alike and in RADIO BROAD- utilizes vacuum tubes as the piece of diverse and so important that it is indeed the CAST Laboratory, a consignment of tubes from apparatus. modern "Aladdin's one manufacturer have been tested that were all lamp." HOW THE TUBE OPERATES Vacuum tubes in the early days were not what alike all twelve of them and they were not they are to-day. Any one who remembers trying specially picked, either. TT IS not necessary for the reader to know * to hook up two of the old "tubular" tubes into Tubes in radio communication serve several much of the theory of vacuum tube operation. a two-stage amplifier knows that. Amplifiers special purposes, but to the listener there It is sufficient if he knows that within the glass in those days were practically unknown. Tubes are two services which are of paramount im- tube there are three metallic elements, a filament did nothing but oscillate, and quite often not portance, detection and amplification. And like which lights up when you turn on the A battery, much of that. All receiving was done by all delicate apparatus, there are certain con- a grid which acts as a controlling valve for the "beats." that is with the tube oscil- plate current which flows from the the around lating and the circuit tuned so that ^_^^ia^ third element, plate, a slight difference of frequency ex- through the B battery and back to the filament. isted between the incoming signals the basic patents on the vacuum lube expired some months ago, there and those in the tube it- SINCE The filament emits electrons, generated las been feverish activity among many manufacturers, and many new names to the of the self. Operators read the signals by have appeared on the market. The result is that a goodly number of experi- according language these difference notes. but in terms, menters are a bit at sea.; tubes with capabilities quite beyond any of tbe previous physicist, ordinary Tubes these stones of all matter were not pumped (as well known types are available and many fans are groping for real information building as as are boiled off the metallic highly evacuated) hard they about them. Tbe far sighted manufacturers who brought out the new tubes, the actually are were alike. filament when it is heated to a to-day. No two power type in especial, deserve much praise, for they have added infinitely to the had certain Some grids on the outside of acoustical refinement of radio. This article, we believe, contains some sug- temperature. the These electrons are glass bulb. Often amateurs gestions which will be highly valued by those experimenters who follow them. It negatively used a of and move toward the complicated system per- is a plea, in short, for our audio amplifiers to be properly planned. By far the charged manent with a magnets placed about the greatest number of radio experimenters use every tube they have in the con- positively charged plate certain on tube so that the electrons ventional way: go volts on the plate and the rated filament voltage. Tbe author, velocity depending various controlable factors. would be drawn from the filament who by tbe way, knows a great deal about high quality in audio circuits, shows at a faster All in The is situated between the pace. all, mod- how the amplifier can be correctly planned which appears almost to be a new grid ern radio listeners have a lot to idea. THE EDITOR filament and the plate and is made be thankful for. of a mesh arrangement so that the Tubes to-day are fairly uniform. electrons can go between its meshes 164 RADIO BROADCAST DECEMBER, 1925 on their way toward the plate. If the grid is operator can look for a high negative it repels electrons and less plate current resistance circuit in which the flows; if it is positive, it draws more electrons tuning is broad until much from the filament out into the space of the tube regeneration is added. Then and the plate current increases. In this way it is time to read up on low the grid is essentially a controlling element. loss circuits. The use of low resistance DETECTOR THEORY AND PRACTICE grid leaks, say one half theory of detection is complicated and megohm, will improve the *~pHE^ will not be described here. It is only neces- quality of music received but sary to say that 41 volts on the plate of the de- on the other hand, low valued Hill- tector is about the correct value with modern grid leaks will cause some loss FIG. 5 highly pumped tubes; that the grid return should in volume which maybe Transformers are used to "match" impedances. In the case be connected to the positive side of the filament; made up in the audio amplifier. shown here, for maximum transfer of power from tube to load, that for grid condenser-leak detection, the proper Various methods of obtain- values seem to be about .00025 m fd. capacity and ing regeneration in a detector the turns ratio of the transformer must be /Zp two megohms, although other values may be circuit have been described VzL used; that there is little use in using a C battery (see RADIO BROADCAST for detector unless very powerful signals are to be October) and all produce the same results. In- the tube up to the limit of distortionless am- creased signal strength, increased selectivity, plification. and, if it is pushed too far, decreased quality. Under these conditions the following table gives the power obtainable, AMPLIFIERS: RADIO AND AUDIO

3-VOLT TUBE 5-VOLT TUBE UX 1 12 ""THERE is little that one can do to a detector I .0066 .0135 .0184 Speaker ^ tube or detector circuit beyond what has Thus it is seen that been mentioned above. When it comes to none of the tubes ordinarily used will sufficient to a loud amplifiers, however, there is much to be said, give output operate FIG. 2 at r and false notions to be discussed. speaker the desired level of .06 watts. many from an antenna several The table the obtain- Signals go through There are two kinds of amplifiers in the usual following gives powers electrical devices before able from tubes under conditions of they finally emerge radio receiver, those which are working at very greater from a loud speaker. This illustration shows input and high frequencies, and those which work at low plate voltages. the path of these signals. At the input and audible frequencies, and there is a league and a B-VOLTS J-VOLT UX-I 12 2I6-A output of each amplifier the voltages and half of distance between them. 90 4-5 .0135 power levels differ, increasing as the signal 90 6.0 approaches the loud speaker In the first place there are two things to con- .0328 '35 9 .058 .118 sider, voltage, and power amplification. These .059 '57-5 10.5 .185 are two different things, and until quite recently received, say in the second super-heterodyne de- little attention has been paid to the difference From this table it may be seen that sufficient tector. between them. Now that we have semi-power power is not obtainable for satisfactory reception Often a detector that will not work on 45 or tubes appearing on the market from several tube with a 5-volt tube until 135 volts are used on the even 225 volts B battery will work very well manufacturers, we shall be able to plan our plate and until 9 volts are placed upon the input indeed on 12 or thereabouts. If regeneration amplifiers with a little more engineering and a to the last tube. Under the same conditions, the is not smooth, that i, if advancing the tickler, little less guess work. newer j-volt, one-half ampere filament tubes, or the condenser in capacity feedback sys- Fig. 2 is a diagrammatic method of showing a such as the ux-H2, and similar tubes foi the tems, is accompanied with growls and low fre- receiver with its component parts. We shall same purpose, will deliver nearly twice as much lies in quency clicking noises, the trouble too begin at the loud speaker and work up toward the power as is actually needed, and with 157.5 volts much tickler, wrong grid leaks, or too much B antenna circuit. on the plate and 10.5 volts C bias will have an battery. The tube should slide into operation The speaker requires power and there is a output that is still more favorable. without fuss, and if it does not, something is certain amount of power that is required by These figures mean that it will not be neces- wrong. With low loss receivers, not much tickler every good one to give a good, well-behaved sary to crank up a receiver to the top notch to is needed. The higher the resistance of the coil sound. For example, the Western Electric hear the average level of an orchestra; and to into which regeneration is being introduced, the 2i6-A tube, which until recently was the only endure distortion, or to turn down the set when more tickler will have to be used and the more semi-power tube available, has an output of .06 a player bangs down on his kettle drums un- erratic will be the operation. watts under the proper operating conditions, and expectedly, or when the orchestra rises to a There is one point that may be mentioned if this is placed upon a good speaker, plenty of maximum output level. here. It is a common statement that there is no volume will result. Such volume will not be In other words, a receiver properly operated necessity for low loss circuits in regenerative sufficient for a large auditorium, it will not be with one of these semi-power tubes in the last receivers since the addition of regeneration re- heard a mile or so up the street, nor will it drive duces the resistance of the circuit. Regeneration any one out of the house but who nowadays does reduce the effective resistance, making wants such volume? tuning sharper, and receiving more selective. Let us say, then, that a good signal requires .06 If the receiver suddenly begins to oscillate after watts and since this figure represents power, the the regeneration has been set say when a crash last tube in the receiver should supply power. of static comes along, or some loud signal, the Now there is an expression, due to Van Der Bijl, which amplifier designers seem to have overlooked, that says that the power output of any HI tube will be as follows.

2 (mu X input voltage) FIG. 4 power = The last tube in a receiver must deliver power 8 X plate impedance to the load which is usually a loud speaker. If

the of the tube, Z . and the load, ZL Now, using this formula, let impedances p are alike, maximum power will be delivered us figure out the maximum power obtainable from several FIG. 3 tubes under the usual operat- stage may always be somewhere short of the A two-stage audio amplifier and the that must voltages appear ing conditions, namely, 90 volts overloading point, and the range in volume, with- at various points along the circuit if the full output of the last B battery, minus 4.5 volts C out the distortion due to overloading, will be tube is to be delivered to the loud speaker. If lower voltages and that the much For the first time in are delivered the volume will be "down." If more than nine battery, assuming greater. practically is radio it is to volts peak are applied to the grid of the last tube, overloading input voltage peak just equal broadcasting reception possible to the In avoid distortion to the will occur and a cone type loud speaker will, in popular par- C battery voltage. overloading without going lance sound, "awful" other words we are working bother of installing power tubes and high voltage DECEMBER, 1925 TUBES: THEIR USES AND ABUSES 165

TABLE I 166 RADIO BROADCAST DECEMBER, 1925

amplifier overloads. Laboratory of RADIO BROADCAST which may be From the standpoint of recommended. These are made by Daven and quality, however, the by Cleartron. The former are known as "MU- prevailing system of 20" tubes and the latter as the "High Constron." having high ratio trans- Both have an amplification constant of 20, have formers first and low proven to be very uniform, and have a plate ratios second is wrong. impedance at 90 volts B of about 30,000 ohms. High ratio transformers Daven tubes are designed to operate on 6 volts will probably have a without the use of rheostats. Since storage lower primary imped- batteries retain their voltage output until nearly ance than will low ratio discharged, the full 6 volts is obtainable. instruments. A detec- These high impedance tubes cannot be used tor has a high plate with profit, in a radio frequency stage of presen impedance while an am- receivers. Their field is in the usage discussec plifying tube has a much above, and Mr. Browning's curves show con lower impedance. If clusively that they are of great value in thi these impedances are to connection. be matched at the all, OTHER POWER TUBES higher impedance trans- former (low ratio) should 'IP HE ux-i2o, a dry cell tube to be used to feec come next to the de- into loud speakers, has an amplification tector. factor of 3.3, a plate impedance of 6600 ohms and should be used with a plate voltage of 135 RADIO-FREQUENCY AM- and a negative C bias of 225 volts. The powe PLIFIERS output under these conditions should be .1 wat IT IS probable that the which is sufficient for high quality high volum ' standard practice of operation, but owing to the curved characteristic using 90 volts B bat- of this tube it is doubtful of this power output be This will be an excellent FIG. 7 tery and negative 4.5 may approached. volts C is about tube for use in which at Curves showing the relation between grid volts and plate current of three battery super-heterodynes use the tube which has power tubes. These curves were made at a plate voltage of 120, and correct for radio fre- present ordinary 3-volt show that a C bias of about 73 could be used on the Daven Mu-6 and quency amplifiers. It not the output required. the 2i6-A while for the Cleartron, and the u\-U2, a bias of about is true that somewhat The ux-2io tube is essentially a power tube 6 would be at 120 volts of B required battery greater amplification and should be operated from a source of alter- will result from the use nating current by means of a step down trans- without forcing. Goodness knows what the of higher plate voltages, but at the same time it former, as was described in November RADIO impedance of loud speakers now on the market is more difficult to control such an amplifier. BROADCAST by James Millen. Only where may be. There is no standard, for there has As a matter of fact, a five-tube set, with two considerable power is desired should this tube been no standard in tubes. Many people try stages of radio-frequency amplification which are be necessary. In the Laboratory it has proved to work cone type speakers on j-volt tubes, and working properly will have all the voltage to be an excellent transmitting tube, and more it cannot successfully be done without some dis- amplification that can be handled. If a potentio- than 30 watts have been applied to it without tortion. Manufacturers of speakers should set meter controlled amplifier is used, and many of difficulty. upon some value of nominal impedance, say the tuned "r. f." sets use this means of stabiliz- At the present time, the proper arrangement 5000 ohms and stick to it. Otherwise some care- ing, a large B battery current will be drawn when of tubes in a five-tube set seems to be as follows, ful designer should bring out an output trans- the potentiometer is swung to the positive side. 3- or j-volt tubes for everything but the last former which will connect a high impedance loud There is no remedy for this, since such sets cannot where a ux-i2o, a ux-ii2, Daven Mu-6, Clear- speaker with a low impedance tube, and a low under existing patent arrangements use C tron 112, Heliotron power tube, WE 2i6-A, Sea- impedance speaker with a high impedance tube. batteries and cannot be neutralized. gull type t, or Goldentone, should be used. At the present time, the best combination If more power is desired, two tubes may be RESISTANCE-COUPLED AMPLIFIERS for a transformer-coupled amplifier seems used in parallel, two may be used in a push- to be a standard 3- or j-volt tube for the A S LONG as radio constructors were limited pull arrangement, or the ux-2io type may be first audio amplifier, and a semi-power tube to the usual 3- and 5-volt tubes, resistance- used. in the last amplifier. Since the amplification and impedance-coupled amplifiers were not to In a future article the new Radio Coporation of 5-volt tubes is considerably above that of be advised. Due to the high resistances used as ballast and rectifying tubes will be described. dry cell tubes, those who wish the best in quality coupling devices, the voltage actually on the The data given in the table in this article must and volume should use the larger tubes. As a plates of tubes is very low, and no amplifier tube not be misunderstood. It gives the maximum final tube, the v\-\\2, the 2i6-A, the Daven will work satisfactorily unless a certain voltage is undistorted power in watts that certain tubes MU-6, the Cleartron semi-power tube, the maintained on the plate. This meant that at least will deliver under certain conditions, those con- Heliotron power tube all are excellent choices double the ordinary B voltages must be used. ditions having to do with the plate voltage used for that last audio stage. And of course for good High "Mu" tubes, however, are a distinct and the variation in grid volts being applied to quality, good transformers must be used. boon to resistance- and impedance-coupled ampli- the tube. If these grid volts are not applied, fiers. Curves taken Mr. G. H. Browning less power will be delivered. TRANSFORMER RATIOS by are illustrative of the effect of using these new For instance, there is an idea prevalent, since ""THERE are several strange ideas prevalent tubes and may be seen in his article on the the appearance of semi-power tubes, that the ^ regarding the ratios of transformers. There Browning-Drake receiver in this number of substitution of such tubes for standard 3- or is no reason why good transformers must be RADIO BROADCAST. 5-volt tubes will result in a marvelous increase low ratio affairs. In fact one of the best trans- Owing to the very high plate impedance of in volume. Such is not the case although some formers on the market has a comparatively high these tubes, they will not act as power amplifiers increase will be noted due to the lower output ratio and for several years before the present at all, and in the third stage of a resistance- or impedance of these tubes over these in standard broadcasting era, the telephone industry had a impedance-coupled audio amplifier a semi-power use. Under the same operating conditions, a high ratio transformer with an essentially flat tube should be used. To get the same amplifi- standard tube and a semi-power tube will de- characteristic. cation and the same power into a speaker liver about the same power. The great advan- The difficulty is expense, and until people will from such an amplifier as is obtainable from a tage of the newer type of tube is that it will pay for high ratio, [high quality transformers good two-stage transformer-coupled amplifier, at handle more power, that is, a greater input volt- they will have to be content with low ratio least three stages must be used, the last of which age and corresponding greater output, than the high quality ones. should be a semi-power tube as indicated before. 3- or 5-volt type. In other words, the substitu- With regard to the overloading of tubes, there Unless large capacities are used as the coupling tion of a 112 type or 210 type tube will enable is no difference whether a high ratio transformer units, at least o. i-mfd., the low frequencies will the user to use greater voltage amplification up comes before a low ratio instrument or not. It be dropped out and the user is no better off than to the last stage and by the proper use of C, and is overall amplification that causes overloading, if he had used transformers. B batteries, distortion due to overloading will and it is seldom indeed that the first audio Two "high Mu" tubes have come to the be less likely to result. OF RADIO ?

Past President, Institute of Radio Engineers

What Is the Matter With the Naval Radio Service?

NLY a short time ago radio had confidently assumed that the operators of compass bearings indicating that the PN-g one of the best opportunities these seaplanes couldn't help knowing ex- No. i was south of the Aroostook, her in its history to prove its worth actly where they were, and could keep in commander flew north until his gasoline o to the mariner in distress and constant communication with the marking supply gave out and he had to drop to failed. It is not in a spirit of vessels. The radio signals were to be used the ocean. The plane's position was then cynical criticism that we bring up this in- for compass bearings as is the case every calculated by her commander as fifty cident but rather with the purpose of in- day with hundreds of ocean-going ships, miles north of the Aroostook. quiring whether something cannot be done and altogether the planes were considered Having thus failed in its important work to prevent similar occurrences in the as safe as though they were close to their of keeping the plane on her course, the future. own home port. Naval radio now scored an even worse The whole country was enthusiastic One of the planes had mishaps and had failure. With no gasoline to run her en- several months ago over the idea of our to give up the trip after covering a short gines, the only thing the Commander of naval aviators hopping from California distance, another never even started. The PN-c) No. i could logically do was to call to Hawaii. Three of the planes were to third flying boat however, PN-g No. i, for help and supplies. It is exactly in go, but due to mishaps only one made a in charge of Commander Rodgers, got well emergencies of this kind that radio is sup- serious attempt at the long flight. This away and picked up the first of the mark- posed to be the mariner's most useful trip had been planned very carefully and it ing ships almost on schedule. The wind agency, but this failure was nothing short seemed as if nothing could happen to pre- was not quite as favorable as had been of dismal. Only fifty miles from the wait- vent the goal being reached. Destroyers hoped, so that the speed was considerably ing patrol ship, the PN-g No. i was for were used to mark the course and were less than that reckoned on. Thus the some inexplicable reason helpless as far ready to render assistance should the gasoline supply was not quite sufficient as radio communication was concerned. planes come to grief; every two hundred to cover the two thousand miles and Com- And to add, to its ignominious failure, miles along the two-thousand mile course mander Rodgers decided to come down radio served to agonize the souls of the a destroyer or a supply ship was stationed near the Aroostook, two hundred miles crew by letting them hear all of the radio to give the planes the proper direction and from the end of his trip, to renew his gaso- messages with which the air was filled. to record their progress. line supply. Gradually, their receiving set told them, The radio equipment of these planes And now, probably the only time during the searchers were giving up hope of finding was supposed to be of the very best. With his trip that the radio channel was really them; each succeeding day their would-be a sending radius assumed to be in the needed, it failed. The radio compass rescuers were becoming more discouraged hundreds of miles, and reliability of opera- bearings should have enabled the PN-g and evidently soon would give up the tion never before attained (as the descrip- No. i to proceed at once to her supply ship, search. And all this time their rescuers

tion of the radio outfits specified), it was but the plane missed her completely. The were only a couple of hundred miles away ! 168 RADIO BROADCAST DECEMBER, 1925

Commander Rodgers is, and we can say frankly that there was a failure, one of the worst that radio has scored. Some ex- planation should be forthcoming from those responsible in the Naval Radio Service for this blot on their reputation. It transpired in the hearing which fol- lowed the disaster several years ago, when six Naval destroyers were wrecked off Point Arguello, that the compass bearings given to the leading destroyer by the Naval radio station were incorrect. The radio RADIO PICTURES OF THE CALIFORNIA- weather intelligence furnished the Sloenan- HONOLULU AIR FLIGHT doab on her recent disastrous trip was or to which Sent from Honolulu to New York on Sunday, September incomplete entirely lacking 13, by the Ranger photoradiogram system. The dis- one might lay a large share of the blame tance is 5116 miles. Left: Commander John Rodgers for the failure of her navigating officers of the PN-Q No. i as he looked when he landed at to avoid the storm which destroyed the Liuhui, Kauai Island, after his rescue from the disabled Listeners who have heard the plane shown in the view above. The ship was adrift ship. way for nine days, owing tofailureof radio compass bearings in which sos traffic has been handled re- when the was about 200 miles from her ship only goal. cently around the New York territory When she landed on the there was no sea, emergency have observed that the Naval stations have the There is no reason a transmitter to signal rescue vessels. The operator good why handled that traffic in a of the plane was forced to hear all the conversations singularly inexpert single circuit regenerating receiver relating to the rescue work fashion. Taken all in all, there are un- could not have been used as a trans- mistakable signs that there is something mitter for the short distance to be radically wrong with the Naval Radio covered, if no other means were at hand. Favorable weather and fortunate winds Service. Who is to blame? But why wasn't there a transmitter which enabled these trans-air travellers finally to of hazardous would work if the plane was forced down? reach land after nine days National Association of Broad- to the a in their craft. And with that According plane's commander, per- drifting tiny casters fect landing on the ocean was made and loyalty to the service which the Navy nothing happened to interfere with the officer feels to be his first duty, Commander THOUGH the average broadcast radio apparatus performing as it was in- Rodgers stated that "there was no failure listener probably knows nothing it of at in air or the A about their of enter- tended to do. Why didn't perform? material any time the it, purveyors Was there no emergency apparatus able to water." tainment have been organized for some operate if the plane was forced down? We are not under the restraint that time. The National Association of Broad-

THE NEW MARCONI DIRECTIONAL BEAM STATION AT DORCHESTER About 120 miles from London. This is a new and exclusive photograph published for the first time in the United States. The picture shows five of the masts which are 277 feet high, and 750 feet apart. The masts are at right angles to the direction in which communication is to be established. The cross arm at the top is 90 feet across. The antenna wires, which are not yet in place, will be attached to triatics at one end of the cross arm and the reflector wires to the other. The distance between the antenna wires, reflector wires, and the number and distance apart of the separate wires making the antenna and reflector will depend on the transmitting frequency used. The installation shown is expected to communicate with New York. Others ow in process of construction and test will connect England with Australia and the Dominions. On a recent four-day test, Senator Marconi announced that he had been in uninterrupted communication with Australia, using the beam system i DECEMBER, 1925 GOOD WORK BY THE ORGANIZED BROADCASTERS 169

Be It Resolved that, it is the sense of this meeting that any agency of program censorship other than public opinion is not necessary and would be detrimental to the advancement of the art."

More Information on Super Power

i THE first experiments on higher broadcasting A power continue, the public is beginning to see that those engineers who advised caution in drawing conclusions as to what effect this increased power would have were wise. Many were the broadcast listeners who said 50 kw. for one station would blanket all that part

DETAILS OF THE RADIO "BEAM" LIGHTHOUSE AT SOUTH FORELAND, ENGLAND Senator Marconi recently conducted tests with this installa- tion from his yacht Eletlra. The beam flashes signals ac-

- _,. .. -

cording to a schedule from all points of the compass. The loud speaker announced a letter at intervals, and the position of the ship was determined according to 'the letter heard. By means of a chart, it was possible to tell just where the ship was. The frequency was 49,970 kc. (6 meters). The heading for this department this month shows the lighthouse and the re- volving antenna and this view shows the details of the antenna casters had its annual meeting this month viso for such an exigency). Now this of the broadcast range, that it would be and its transactions are indirectly of in- association has changed its point of impossible to receive other stations which terest to us all. The object of the society view. Among other resolutions passed was sent signals of anywhere near the same is to promote generally the welfare of our one which would put the broadcasting of frequency. Some months ago we got sev- broadcasting stations through various co- copyrighted material on the same basis eral petitions (with requests to sign) directed operative arrangements. as the mechanical reproduction of such to Mr. Hoover, requesting that he prohibit It was started by a small but active pieces (by player piano and phonograph) broadcasting stations using a greater power group in the Middle West, with the able in so far as royalties are concerned. than 5 kw. The petitions stated what Mr. Paul B. Klugh as Executive Chairman. Another matter which received consider- troubles were to be encountered if the Its activities proved so worth while that ation was that of the method of introducing Department did not block this anticipated the membership rapidly increased and now the paid features of the program. One of move by the "Trusts." it bids fair to justify its name. our congressmen has advocated the com- Schenectady has carried on many tests Among the members elected at this meet- plete separation of paid channels from the with a 50 kw. outfit, and at the time this ing was WEAF, representing the American others. That attitude seems unnecessary is written, very few complaints have been Telephone and Telegraph Company. When and inadvisable. The broadcasters took this received. Many replies have been re- this company goes into an association of view of the matter and decided that paid ceived to questionnaires sent out, and they this kind it is undoubtedly a sign of its programs could be "gently" introduced. are still being classified and compiled. promised or accomplished success. On the question of censorship, the society It is interesting to note that the public The question of broadcasting copy- declares that "Whereas it is universally must be depended upon to answer the righted material has been more troublesome agreed that the success of radio broad- question as to how much power the broad- to the National Association of Broadcast- casting is founded upon the maintenance casting agencies should use. All question- ers than any other problem in their opera- of public good will and that no broadcast- naires received should be carefully an- tions. At first the organization was averse ing station can operate successfully without swered, for it is the facts in the compila- to paying royalties for the privilege of an appreciative audience, and Whereas the tion of these answers that Mr. Hoover will putting music and songs on the air (the public is quick to express its approval or depend on to determine his future policy copyright law, of course, contains no pro- disapproval of broadcast programs regarding high power stations. 170 RADIO BROADCAST DECEMBER, 1925

of the Although many letters received quality reception for the most listeners is The Facts About the Farmer and WGY are by contradictory, the average what radio must eventually supply and Radio listener seems to think that a 50 kw. signal increased power, properly controlled, will is two or three times as loud as a 25 help in the solution of this problem. benefits which radio confers kw. signal. In the recent tests, the two THEon the farmer have been repre- powers were alternated so that repeated Canada as Our Instructor sented to him repeatedly, but it is comparisons could be made and but few a fact that no one has really known whether of the reports say that one signal is more MUST congratulate our Cana- the average farmer profited by broadcast- than ten or the De- times as strong as another. As dian friends on the way their gov- ing not. A recent survey by a matter of fact, theory would indicate WEernmental radio activities are partment of Agriculture among the coun- that the 50 kw. signal is twenty times as conducted. It has been noted before in try's farms yields the information that there as strong as a 2^ kw. signal, yet most of the these columns that many radio questions are 553,003 sets on farms, not listeners it is as This say about twice as strong. were tackled in an intelligent and reason- many we had expected. repre- sents of the Probably the signal is actually twenty able manner by our northern neighbors, only 85 per cent, country's as so there is still a market times strong and the factor ten by which even though some of their procedure (such farms, large virgin the for average listener misses the truth is as the licensing of receiving sets at one the active radio manufacturer. due to his lack of skill in comparing noises dollar a year) may not meet with our A questionnaire was sent out and the of different strengths. approval. returns for the State of Pennsylvania The have been sent us Mr. F. unexpected absence of complaint There has just come to hand a pamphlet by George regarding interference by the high power put out by the Radio Branch, Department Johnson of the Department of Agriculture channel has encouraged the General Elec- of Marine and Fisheries, Ottawa, which at Harrisburg. Of 343 answers received, tric engineers to continue their tests and takes up the question of regenerative re- two thirds used tube sets with loud speak- the Department of Commerce has given ceivers. It is a circular letter addressed ers. To the question "Have market re- WGY permission to use 50 kw. regularly on to all broadcast listeners and is written in ports ever made or saved you money?" and half "Yes." and half Saturday Sunday evenings. If this a manner which will appeal to the average exactly answered much power is found to give to the broad- non-technical man. The letter starts with "No." We hasten to encourage the pro- cast listeners more trouble than benefit the paragraph "When using a receiver of moter of "radio for farmers" after this it will be it first as discontinued, but it is almost sure the regenerative type for the reception of answer, because while looks at radio that such will not be the case. A few radio telephone programs, please avoid in- though was not functioning very well listeners near the station who want to hear creasing regeneration to the point at which here; that is really not the significance of other stations thousands of miles away, the receiver begins to oscillate, otherwise the return. That fifty per cent, of the is farmers saved the information whose frequency nearly the same as you will cause interference with neighbor- money from Schenectady's, will of course report inter- ing receiving equipment." Are you doine conveyed over the radio channel is in- ference. This can be predicted without any your best to observe this? controvertible evidence of its utility. further tests. But as radio broadcasting de- The letter then proceeds to give an the of the velops complaints distance hound elementary, but clear and correct analysis will fall less upon sympathetic ears. High of what regeneration is and why it causes The Month in Radio interference, ending with easily followed instructions as to how employment agencies are to avoid spoiling ENGLISHfinding that domestic help appre- neighbors' reception. ciates radio possibly even more With the govern- than does the mistress of the house. Bast- ment list of listeners ing the roast beef in tune with the wedding available, as a result marches, or washing dishes to the time of of the licensing fea- modern jazz proves to be so appealing that ture of radio recep- the agencies are said to be actually classify- tion in Canada, this ing the vacant positions as radio and non- circular should reach radio, much to the detriment of the latter. the owners of nearly all the radio sets in first attempts experimentally to that country and THEdetermine the proper allocation of should do a deal of frequencies to the various European sta- good. tions resulted in ethereal pandemonium,

HOW THE CANADIAN RADIO SERVICE HELPS THE LISTENER The "Inductive Interference" car maintained by the Radio Service of the Canadian Government. The annual license fee of one dollar, paid by every Canadian listener is used to maintain a corps of inspectors. A specially trained "induction squad" operates with this car to locate interference hard to detect by the ordinary methods. The car is especi- ally made for this purpose, with a body of insulating material and care- fully screened ignition system. Two special super-heterodynes, several portable receivers, a sledge hammer, condensers, jand chokes form the equipment of the trouble car. The chokes and condensers are applied to cure trouble when found. The sledge hammer is often used to tap electric light poles in a suspected territory, and the trouble is quickly located by a listening inspector DECEMBER, 1925 WHAT PEOPLE SAY ABOUT RADIO 171

thorium diffusing to the surface from in- side the filament. Now, it is announced, solid thorium fila- ments will soon be available. This is a real advance because the possibility of the dis- appearance of the thorium atom-deep layer no longer threatens. The new tubes will very likely have much longer life than the present ones and not be so sensitive to improper adjustments.

A RECENT discussion in the semi- '* popular press, having to do with the use of super-power, ventured the statement

that if a 5 kw. station was audible on a crystal set at twenty-five miles distance, the 50 kw. station would be audible on the same crystal set for a distance of "several hundred miles." It seems that if we interpret "several hundred" as five hun-

dred miles, the power of the 5 kw. station Harris & Ewing would have to be increased to at least 250 SENATOR C. C. DILL kw. to increase the crystal set range as CARDINAL HAYES ^Washington; United States Senator' much as the writer suggested and then New York; Speaking at the opening , for Washington of it would probably fall short. Schenectady's station WLWL: " The organisation a Government Com- tests should soon give us some reliable of "Among the most recent and wonderful mission on Communications to act the information on this for point. gifts of science comes the radio. As Cardinal telephone, telegraph, and radio, such as has Archbishop of New York, I congratulate the been proposed, would probably end in disaster ACCORDING to the of Paulist Fathers upon the great work they for broadcasting.. It would be the beginning Department * have undertaken in opening up station WLWL. of the end of freedom of action in the radio Commerce, Japan's long distance / congratulate also the people of this immense business. I also wish to emphasise the neces- radio stations are to from telegraph pass city and of this whole country of ours upon sity of immediate action on the part of the the control of the government into the the inauguration of an enterprise so admir- United States Supreme Court to arrive at a hands of a which able. May I add that in the building of this decision the private company expects regarding broadcasting of copy- station, the Paulists have shown themselves righted musical numbers. If it is decided to erect two new stations in addition to worthy sons of their founder, for nothing was that such broadcasting is done for profit, the two now in and that when operation more characteristic of the first Paulist, Isaac and therefore a fee is due to the publishers of their four stations are in operation the com- Hecker, than this readiness to every the music, I intend to introduce a bill to utilise will communicate with the new instrument of good. How his noble regulate the payments, so that radio broad- pany directly soul would rejoice to witness this scene, the casting will not be at the mercy of any one United States, Germany, and France. With dedication of the twin towers of steel that over- group of men." the kw. of which the new stations 50 power look the Paulist Church here at Fifty-ninth are to have it seems very unlikely that Street, as an agency for the spread of truth and wisdom. We who radio are signals can be sent directly to Europe employ responsible for our use of it. We must take to a from except under most favorable conditions. according dispatch London. care that we use it not for harm. But, further, Most of the time one or two stations About sixty stations going at once in an relay we are strictly bound to use it for good, will be if relia- to make it Whoever would be expanse of territory perhaps less than a undoubtedly required any fruitful. great, is to be obtained. must serve. He who has power must turn it quarter the area of our country proved too bility to the welfare of his fellows." much. The interference was truly inter- national. Newcastle, England, heterodyn- with Gratz, Austria, and sta- ing Norway Interesting Things ness of this situation, playing a gambling game tions with some in Ger- in which no limits beating England, Said are set where the more he many and France, show us what a difficult Interestingly pays the more he will have to pay and you will question the Europeans have compared to appreciate how serious the situation is." ours. The radiophone center in Geneva DOWEL CROSLEY, Jr. (Cincinnati; presi- ALFRED E. SMITH (Albany, was notified of all the interference and in ^-*GOVERNOR dent Crosley Radio Corporation): "Very New York): "Radio broadcasting has the next test will be made period changes few broadcasting stations are operating with revolutionized political campaigning. It makes to the stations farther keep interfering any direct profit. No broadcasting station in it possible for a candidate to reach the by-ways in apart frequency. the country is making money to-day. Some of politics. The stay-at-home gets your message handle indirect advertising with some source as clearly and intelligently as the man who is of revenue; so far, I believe, no stations have able to come out to the A ""PHE research laboratory of the West- meetings. great * been able to meet expenses with this income. event can be recorded at the fireside. The inghouse Company announces that the Our own revenue at WLW from this source would opening of the extraordinary session of the metal, thorium, is now available in such not pay for the direction of the studio. We have New York State Legislature this year is an quantities that the filaments of vacuum a large investment in broadcasting equipment example. It brought to the people young and tubes be made of thorium instead may pure whether it is profitable for us to broadcast is a old an important lesson in civics and gave them of thoriated tungsten as is now the practise. question; whether the good will created by a exactly the procedure which occurs when a The present tubes have a layer of thorium broadcasting station justifies its continued session of the Legislature is opened. Radio on the surface of tungsten filament, the existence is merely a matter of opinion. No one gives you the widest possible audience and also can check the results. If all the benefit of I have had oc- layer being only about one atom deep. broadcasting public opinion. stations face an additional expenditure of from casion to use the radio on If the filament is improperly used, this many important $5,000. to $50,000. per year, due to the royal- occasions including my inauguration as Governor thin layer of thorium disappears and the ties imposed by the Society of Composers, and in making an appeal for public support electron emission practically stops, the Authors and Publishers, and perhaps more, be- of important and vital policies. Just as it has tube is useless. overheat- By considerably cause no limit has yet been set how many of served my needs and opened up a tremendous ing the filament, without B batteries, a new these stations will continue? Imagine the avenue for political education, I am glad to have of thorium will layer appear, this new feelings of a man who appreciates the serious- the opportunity to say so to the radio public." A Five-Tube Receiver of Dual Efficiency

A Late Development of the Famous Browning-Drake Receiver Employing Impedance- Coupled Audio Amplification Producing the Highest Quality Some Valuable New Data on Radio-Frequency Transformers and a New Method of Balancing Them By GLENN H. BROWNING

UESTIONS are frequently being and laboratory work by Mr. F. H. Drake regeneration is present in any radio- asked concerning the necessary and the writer, with a result that a piece of frequency amplifier to a greater or less requirements of the ideal radio apparatus was designed, which gave almost extent, and the necessity of providing a receiver. The answer pictures a 90 per cent, of the amplification predicted method of controlling it arises sooner or set which is sensitive enough to by mathematical calculations. later. A little experimenting showed that receive great distance, gives perfect repro- Several interesting discoveries were made greater signal strength could be obtained duction of the program being broadcast, during this time, among which was the by balancing the radio tube and regenera- tunes sufficiently sharp to separate trans- fact that the "turn ratio" of a tuned ting on the secondary of the radio frequency mitting stations, does away with interfer- radio-frequency transformer was not so transformer, rather than regenerating di- ence, and accomplishes all rectly on the antenna tuning this without batteries, _ The former course, tubes, ^ javj system. or other trouble making de- besides giving greater signal vices. At the has the ad- present time, A L THOUGH Mr. Browning lias made Jew fundamental changes in the origi- strength, added * ^ our ideal seems far from the nal design of the justly famous Browning-Drake receiver which was originally vantage that it does away realm of realization, but at described in RADIO BROADCAST for December, 1924, the reader will find that the re- with any radiation tendencies ceiver described here contains some distinct which this model in least we may take a step in improvements place the receiver might otherwise the current receiver The are in the audio circuit, the right direction, by scien- vanguard of design. improvements have. and impedance-coupled amplification has been chosen. The four-tube model of the tifically investigating radio Browning-Drake receiver does frequently overload, but the set described below is and audio frequency ampli- SELECTING THE AUDIO almost free from that disadvantage. In this article, the author presents some inter- fication. esting data on comparison between transformer-, resistance-, and impedance-coupled AMPLIFIER The receiver to be de- amplification, and suggests a new method of balancing the radio-frequency trans- scribed, which consists of one former. It should be read with much interest. THE EDITOR. TN CHOOSING an audio 1 stage of balanced, tuned radio amplifier for the circuit, frequency amplification, re- tstf some experimenting was generative detector, and three necessary, as one can use stages of impedance-coupled. audio ampli- important as the resistance of the secondary transformer, resistance-, or impedance- fication, is still far from perfect, but it is circuit, and the relation between primary coupled systems with varying results. Two sensitive enough to do DX work, selective and secondary. It was also found that stages of, say, 4 to i transformers will un- enough to cut through locals, is properly any capacity between these two windings doubtedly give sufficient volume, but the designed for good quality reception, and tended to decrease the efficiency, so that quality or naturalness of the received pro- does not radiate. the final design consisted of a "bunched" gram must, in some measure, be sacrificed. Let us consider the component parts primary winding coupled closely to a Three stages of impedance-coupled am- separately. The tuned radio-frequency low resistance secondary coil. Having de- plification has as good quality as resistance, transformer is probably the most important signed the radio frequency part of the cir- and, if properly built and operated, gives part of the receiver, for into its develop- cuit, the question of regeneration was then greater volume and does not require an ment went almost a year of theoretical encountered. As most radio fans know, abnormal B battery voltage. It was con-

OltolOmfd. O.ltol.Omfd. O.ltol.Omfd. DAVENTUBE ., DAVENTUBE II DAVENTUBE

67!sV.or90V.

FIG I [] 'i Amp. Ballast for 5VoltTubes ti % Amp. Ballast for Power 5 VoltTubes

The schematic diagram of the circuit employed in the receiver. The several battery terminals of similar markings are paralleled and connected to the terminal of the indicated polarity of the battery in question. For instance, there are four minus A posts. This group is connected together as one terminal, thence connecting to the proper battery. The same holds true of the two plus B 45-volt terminals, and the three plus B 6yj-volt or go-volt terminals. However, in the case of the minus C battery terminals, the last audio stage will require more voltage than the first two DECEMBER, 1925 A FIVE-TUBE RECEIVER OF DUAL EFFICIENCY 173

sequently chosen for the receiver to be x Shaft Threaded with described. 10-32 Die in For those who are interested labora- Split and Tapped tory measurements, a comparison between For 10-32 Thread the three systems is shown in the accom- panying chart, where signal strength is plotted for frequencies ranging from 100 to 10,000 cycles per second. It will be seen that the more constant the amplifica- Brass Bushing ,-'' Thread tion for the frequencies shown, the better 10-32 FIG. 3 is the quality of the received signals. mechanical of the bal- The conclusion to be drawn from this Shows the arrangement ancing condenser plate and mount. It is to data has lead us to choose three-stage be mounted on the sub- panel in the rear of the impedance-coupled amplification with high- radio frequency secondary coil Mu tubes. The parts listed below were used in build- One 18 x inches. FIG. 2 sub-panel (bakelite) 7 ing the set. Whether or not the builder One National Kit (containing the two variable Details of the winding of the radio frequency follows the exact list given, he will need the condensers and Browning-Drake coils.) i coupler. L} is the primary; La the secondary, listed below or their Five Na-ald sockets (2 and 3 uv-2oi A). and Lp the variable tickler coil. The actual parts equivalent. uv-igo, One Daven Leakandenser (the leak shot) Id winding specifications are contained in the ac- companying article One panel 21 x 7 inches. have a resistance of 6 to 8 megs.)

Use No. 19 Drill for Holes not Specified

_._,_*.-.

y_

" -- 10 V 2 -\ 21' H FIG. 4 The panel layout. There is room enough between the two tuning condensers to include a filament voltmeter which would not only add to the appearance of the receiver, but prove exceptionally advantageous in knowing the value of voltage delivered to the tubes

RADIO BROADCAST Photograph

FIG. 5 Looking down on the sub-panel, the position of the balancing condenser may be observed. Much of the wiring is below the sub-panel 1925 174 RADIO BROADCAST DECEMBER,

RADIO BROADCAST Photograph FIG. 6

The simplicity of assembly is evident from this view. Note that the two coil units are at right angles to each other and on the same plane. This is necessary to prevent uncontrolled oscillation

Three Daven .1 wire on a three-inch megohm grid leaks, bakelite tube. As and mounts. has been mentioned Three loo-henry before, the resis-

National chokes. . tance in this circuit One Yaxley filament is and a - * , important, control jack. 1 of One .001 mfd. fixed great quantity data has been col- by-pass condenser. One .0001 mfd. fixed lected which would condenser. indicate that the re- One balancing de- sistance of a single- vice. layer solenoid is Nine binding posts. RADIO BROADCAST Photograph somewhat lower FIG. 8 than those wound in The panel appearance of the completed receiver: simplicity itself Fig. i shows the a so-called "low schematic diagram loss" manner. The of the circuit used. The antenna tuning coil construction are given in Fig. 2. The rotor coil Lp is made up of 20 turns of No. Li consists of 46 turns of No. 20 d.s.c. wire primary, L3, consists of 24 turns of No. 28 28 d.s.c. on a 2|-inch form and so mounted on a three-inch bakelite form with a center or 30 d.c.c. wire, wound in a groove and that it may be rotated with respect to the tap taken off. The radio-frequency trans- placed at the low potential end of the secondary of the tuned radio-frequency former, commercially familiar as the secondary coil (under the first few turns of transformer. The condensers chosen to " regenaformer," consists of three windings, the secondary at the filament end). The tune the two circuits are of such construc- a primary, a low resistance secondary, and secondary, L2, is a single-layer solenoid tion as to separate the high frequency a rotor coil. The details of its mechanical made by winding 75 turns of No. 20 d.s.c. (short wavelength) stations considerably

RADIO BROADCAST Photograph FIG. 7 An under-view of the sub-panel where most of the wiring is placed. Convenient holes in the sub-panel allow the passage of wires connecting parts above the sub-panel with those below it DECEMBER, 1925 A FIVE-TUBE RECEIVER OF DUAL EFFICIENCY 175

700 more than the ordinary condenser, and for good quality recep- their sizes are such as to cover a frequency tion. spectrum from 600 kilocycles to 545 kilo- Forty-five volts is rec- 600 the cycles (200 to 550 meters). ommended on both of choke coils is The construction the radio-frequency ampli- 500 of the of fier and as this z not described because difficulty detector, o making them at home. The National 100- voltage has been found < henry choke was used in "the model de- more efficient on the de- scribed. However, any standard choke tector and sufficient for coil for audio frequency work may be em- the radio frequency tube. ployed, such as those made by Acme, the With 45 volts on a radio- General Radio Company, AmerTran, and frequency amplifier, no Thordarson. C battery is needed and the grid return is run CHOICE OF TUBES directly to the negative IN EXPERIMENTING with the re- side of the filament. 1 ceiver, it was found that a uv-igg was In laying out the ap- much easier to balance than the larger paratus so that the set tubes, and was consequently used as the would be compact, the radio-frequency amplifier tube. As most tuning condensers are fans know, a uv-igg is also a good detector, placed symmetrically on so at the suggestion of Mr. Arthur Lynch, the panel with the tube the two uv-igg tubes were put in series sockets arranged as and three Daven six-volt tubes employed shown in the photo- so that the set operates directly from a graph, the radio fre- six-volt storage battery without the use of quency tube being the rheostats. Two Daven MU-2O tubes may one on the extreme left be used in the first two stages of impedance with the detector on the with a Mu-6 in the last stage. The con- extreme right, and the structor may use other tubes by placing the audio tubes between the correct filament ballast such as Amperite, two. Brach, or Daven type in the battery leads CONSTRUCTION DETAILS of the respective tubes. A five-volt, J- ampere tube would take a j-ampere ballast, and a five-volt, ^-ampere tube would take a ^-ampere ballast, etc. The new power tube, ux-i 12, may be used in the last audio stage with about 1 3 5 volts on the plate and g volts C battery. A separate C battery binding post is provided so the last audio tube may have an independent bias battery. When the Mu-2o tubes are employed in the two intermediate stages of audio, little or no bias is needed with go volts plate battery, but when higher voltages are used a C battery of 15 to 3 volts should be employed 176 RADIO BROADCAST DECEMBER, 1925

stations on the head- A few notes on tuning may be helpful, phones, is absent with though actually operating the set is the the impedance ampli- only way one can acquire the knack of

- fier. Instead of us- DX work. If the set is . I Calculated Radio Amplification doing performing - the can II Measured Radio Amplification ing a filament switch, normally, volume coil, Lp, be turned

Ill-Measured RadioAmplification the is made to do to such a that a on g jack position placing finger of Transformer with 8 Turn Primary double duty, so that the stator plates of the .00025 mfd. con- the in in 5 placing plug denser gives a "pluck" the receivers. the jack lights the This means circuit L,, Q, is oscillating. tubes. With the volume coil in that position, turn the dial of the .00025 mfd. condenser BALANCING AND until this whistle is loudest and adjust the OPERATING THE volume coil until the whistle disappears, RECEIVER and by slightly retuning, the station 400 should come in. If the detector tube has first thing to a to into oscillation THEdo after the re- tendency "snap" in- FIG. I I stead of in the ceiver has been con- going gradually, resistance Three curves which are both interesting and instructive. Note how of the grid leak should be increased. structed as shown, is approximately correct in comparison is the calculated and measured The receiver described is capable of radio frequency amplification while manifestly the 8-turn primary to balance the first for not is it a is not as good tube so that no radi- extraordinary results, only fine distance but of the re- ation will occur, and getter, quality ceived concerts is almost above reproach. also be kept well away from other con- in such a way that greatest signal strength Combined with this is its non-radiating nections. A center tap is provided on the will be obtained property, and the fact that an extremely first coil, L,, to be used with a long antenna Connect batteries, phones, and ground to short antenna of only ten or twelve feet of of loo feet or over, but as some antennas, the set, but do not connect the antenna. wire may be used with satisfaction. which are even much shorter than this, Turn the rotor or tickler coil to a point have a large amount of capacity, it is well to where placing a finger on the stator plates make the connection from the .0001 mfd. of the condenser, a loud Q, gives "pluck" -tev condenser to the point of the coil which in the phone. This shows the secondary makes the two dial settings most nearly of the radio-frequency transformer is Concerning the Receiver Which coincide at mid-scale. Only one is oscillating. Now rotate the coil until jack Are used, as most radio enthusiasts use a loud oscillations cease, as determined by the Commonly Asl^ed speaker except when tuning for extremely finger test. The first condenser should Q. What is the trouble if the receiver tunes distant stations, and then it has been then be turned through its range, and if, broadly? found that three of at of this the secon- stages impedance- any setting condenser, The .0001 mfd. condenser in series with the the transformer coupled amplification can be used conve- dary of radio-frequency antenna may be of incorrect value or an niently with head phones. This is due to oscillates, the balancing device should be excessive amount of loss would give this the fact that the noise which is apparent adjusted until this test is satisfactory, and effect. The blame might also be laid to with transformer coupling, and which tends the two tuning circuits are entirely inde- poorly soldered connections to the two coils, Li and La. to draw comfortable reception of distant pendent of each other. Q. What makes the detector tube go into oscillation with a "snap" instead of going in gradually? A. The grid leak is not the correct size. Try one whose resistance is higher. The grid condenser might be larger than .00025 mfd. (It is much better to use a condenser smaller than .00025 mfd- rather than one larger). Q. What length and type of antenna works best with the receiver? A 50 to yo-foot antenna is usually ample with as much of this vertical as possible. Very good results have been obtained with a piece of wire about 30 feet long extending from a pine tree down vertically to the receiver. Will the set work with a loop? Yes: but even an antenna of fifteen feet located in the same room as the receiver has been found to give better results, and is easier to erect.

FIG. RADIO BROADCAST Photograph

A compactly built modification of the Browning receiver, which could be made to fit in a phonograph cabinet as described in this magazine for June, July, and August 1925. This one employs re- sistance-coupled audio amplification. The amplifier units are situated below the sub-panel Point or Vieuu- KJndsleu tHcllcs ondiuFted by o *

Is the Popularity of Jazz Music Waning?

" "HEN radio broadcasting was 1 believe," writes D. M. Craig, of La- dance orchestras, or to soloists who ha< a novelty and one called in mar, Missouri, "that the universal con- nothing on their repertoire but whateve the neighbors to hear the demnation of jazz is contrary to the true numbers were being sold in the musii voices coming in "right out of feeling of a majority of radio listeners, if shops as "the latest thing" or, worse, t< wi " " the air," little or no attention was paid to all music is classified as jazz. Would these song pluggers in the employ of the musi what the voices were saying. "Radio is a objectors want to stop the broadcasting of publishers. This practise of the broad marvellous instrument, a tremendously such organizations as those of Paul Whit- casters, we firmly believe, has shortene< potential medium, but what difference does man, Vincent Lopez, Jean Goldkette, and the life of many moderately good popula it make if it is being used to give currency many others?" Decidedly not. While numbers, which otherwise might have re to worse than second-rate stuff," is about there are those who are utterly opposed to tained popularity for a considerably longe the gist of the very vocal objections made jazz whatever its origin, the more liberal time. by these observers. George Jean Nathan, among us recognize that jazz music has a Mr. Frank McEniry, of station KOA a the rapier-worded dramatic critic of The very strong hold on a large percentage of Denver, in answering a recent inquiry o American Mercury said in a recent issue of the public of several continents, that it is ours about this subject replied: that green-jacketed organ of dissent: not wholly as bad as it is pictured, and that, On the whole, 1 believe listeners tire of jaz in moderation, jazz is excellent entertain- Nightly the front parlors of the proletariat re- much more quickly than they do of the classics sound to strains of ment. the alley jazz pounded out by or semi-classical presentations. This belief i bad hotel orchestras, to lectures on Sweden- The trouble with broadcasting programs, of course, wholly a personal one, but it is base< borgianism by ex-veterinary surgeons, to songs and up to the past six months this has on a daily study of mail from our listeners. Her ibout red hot mammas, and Beale street melan- been true of almost every American sta- is an excerpt from the letter of a Western listene cholias vaudeville . . which seems of a mass of mail w by hard-up performers. tion, is that they have been too heavily typical great are on the "One cannot b Now all the criticism of radio programs loaded with this orchestra and that, play- receiving subject: unmindful of the lovely entertainment last even made along these lines is true in that it is ing the currently popular tunes. Too ing; especially beautiful was the Floradora Sex possible to hear the thing described from much of the program has been devoted to let by the Municipal Band. Likewise, the sam some radio station or other at one time or selection with the lullaby on the saxophone. I another. We should not broadcast- judge was such a relief from the slap-stick stuff one get ing by that method any more than we from many stations." That letter was fror should judge the thinking processes of the Charles G. Hickman of Forsyth, Montana. ' American citizenry by what we hear a And here is another from Mrs. Walter Burk chance street orator mouth. Broadcasting of New Plymouth, Idaho: "Almost without ex we like the better class of music. is not nearly as badly off as its hostile critics ception, Jaz ceases to have after the first two o would have you think, and the aerial any appeal three selections it is all alike. . . -." offerings of the radio season now upon us are daily justifying that belief. are some a " They doing good things If it for weren't the constant stream of KOA, and by the time this magazine is ii jazz flowing from nearly every broadcast- the hands of the reader, the competitivi ing antenna," remarked a listener to us the of classical music as t< " program opposed other day, I would enjoy radio a lot more. jazz music will have been given from tha These orchestras jazz from every, station station. All the listeners will have ; in the country, all practically banging away chance to express their opinion and a com at the same piece at practically the same plete record will be made of the results time are much more than annoying." The We hope to announce the findings in ai trouble a with criticism such as this is that early number. There should be some in it groups all dance music ,as jazz, which is teresting letters after this contest. only true because we have no term which Mr. Freeman H. Talbot, that abli allows us to distinguish between the grades musician responsible for the programs o of jazz. We use the same term to describe KOA set down some of his thoughts aboui the FRANK \V. ELLIOTT soft symphonic effects of Art Hickman, the subject of jazz especially for this de Ben and The new president of the National Association Bernie, Vincent Lopez as we use partment. "For many years," he says of Broadcasters, who succeeds Eugene F. for the fifth rate Five of music critics have been an- Melody Kings McDonald, of Chicago. Mr. Elliott is business periodically Four Corners, Oklahoma. manager of station woe at Davenport nouncing the death of jazz. Probably th( 178 RADIO BROADCAST DECEMBER, 1925

so-called music of jazz is largely responsible which has brought improvement in its the taste of the radio public is changing, for the belief that it is moribund. To tone, consider some of the "indirect adver- and for the better. those who would shed no tears over its tising" programs put on through the WEAF a most chain of stations. Here is what the direc- demise, jazz displays disheartening A New Note in Broadcasting: it arises fresh after tor of for that station, Mr. vitality. Phoenixlike, broadcasting Cooperation each reputed annihilation." Mr. Talbot J. A. Holman, says about them: "Pro- continues: grams have been presented of a type that O MOST listeners in this country previously would have been considered im- east of the Mississippi River who Jazz has been called primitive, uncouth, banal. possible by radio impossible in the sense T;heard the of the radio It has been charged with disrupting homes, broadcasting that they assumed too high a degree industries dinner from the Commodore weakening Church ties, and undermining the of musical and culture on the morals of the nation. Personally, 1 feel that jazz general Hotel not so long ago, it probably seemed The' is not all bad it is not clever enough for that. part of the radio audience. public as if very little was occurring except the It it is at their real value and en- may be banal, and at times discouragingly accepted them presentation of an exceptionally fine purely stupid, but it is not essentially bad. Lately, thusiastically availed itself of their educa- entertainment program announced by the has to itself some notable defend- jazz gathered tional activities. . . . No music was active Major J. Andrew White. A good ers among the musically correct. Serious too For "highbrow." example, George program it was, too, with some of the Capi- minded musicians have perceived under the bat- Orchestra Barrere's Little Symphony pre- tol radio family, the Happiness Boys, the tered and tattered appearance of jazz, evidence sented a series of chamber music recitals, Will he of a new vitality in music, a struggle after a new shy Rogers, busy explaining why which while beautiful and perfect gems of was not Vincent form of expression, crude as the hieroglyphics of there, Rudy Weidoeft, instrumental music, are con- Cubism, but genuine art, nevertheless. generally Lopez and his Orchestra, and several sidered above the and The moans, shrieks, cat calls and sobs of jazz understanding ap- speakers, including Senator Dill. The of music lover. will eventually disappear, but the vibrancy of its preciation the average radio lambs and lions, however, were lying will remain to be fact is that the American stimulating rhythms caught The interesting down together and at executive sessions some time a master on a new work by composer public welcomed the innovation. . . ." before and after the dinner, various as- series caco- or of works as revolutionary as the The radio audience is not to listen required sociated organizations arrived at some phonies of Wagner. to the sad stuff outlined Mr. altogether by decisions whose effect may be far reaching. Nathan. The are unmistakable that How do all these remarks apply to pre- signs The National Association of Broadcast- sent programs? Well, they are some of the ers, whose member-stations include a good signs if indeed any are needed which proportion of the broadcasters of the show that the old preponderance of jazz country, elected Dr. Frank Elliott of station on programs is greatly lessening. For some woe at Davenport, president, succeeding time, one of the two outstanding stations E. F. McDonald, Jr., of station WJAZ. in New York City has had a rule, somewhat And among other applicants, station flexible, it is true, that no dance music can WEAF, New York, was admitted to mem- be broadcast until after ten thirty in the bership. This is somewhat important, be- evening. Mr. Carl Dreher discusses this cause thus far, WEAF has played a lone matter more fully on another page of this hand in broadcasting. It probably means number. The fact that the musical parts that broadcasters are going to cooperate of programs are being more devoted to more to a greater degree than ever before, with serious efforts by stations in nearly every inevitable benefit to the listener. part of the country except Chicago, simply Ever since the first broadcaster was li- means that there is less time left for jazz. censed, there has been a quarrel on be- To mention a specific type of program tween the owners of the radio stations and

REINALD WERRENRATH, MME. LOUISE HOMER, TOSCHA SEIDEL, AND A. ATWATER KENT The Atwater-Kent Manufacturing Company has arranged a series of Sunday evening concerts given at 9:15, Eastern Standard time through WEAF, WCAP, WJAR, WEEI, WCAE, wsAi, wwj, woo, wcco, WGR, woo, Kso, and WTAG. The series presents some of the best-known artists familiar to concert- goers and is regarded by radio listeners as one of the real treats of the Fall and Winter radio season. There will be thirty concerts and the last will be given some time in May, 1926. Mr. Werrenrath, baritone, gave the first concert on October 4th, and was followed by Mr. Seidel, the well known Rus- sian violinist. Mme Homer, the contralto of the Chicago Civic Opera Company, presented a popular program as the third concert of the series. Mr. Kent is shown in the photograph at the top DECEMBER, 1925 179

JEAN GOLDKETTE AND HIS LITTLE SYMPHONY ORCHESTRA AT WJR

The photograph at the left shows one of the orchestras heard regularly from station WJR. Left to right: J. Schwatzman, celle; Gaston Brohan, bass; M. Shapiro, violin; Victor Poland, violin; Jean Goldkette, pianist and conductor; Joseph Corner, violin. The Book-Cadillac Hotel is shown at the right and houses the Detroit studios of WJR-WCX. The transmitting apparatus of the two stations operating on 580 kc. (517 meters) is located at Pontiac, Michigan the organization which claims to have con- Radio Plums for the Present Paul Althouse, Arthur Middleton, May trol of most of the copyrighted musical Season Peterson, Paul Kochanski, Mischa Levit- numbers, both popular and more classical ski, and Hulda Lashanska. the American Society of Authors, Compos- the optimistic estimate of Then there are the concerts of the Victor ers, and Publishers. This Society to the Mr. W. E. Harknessof the Ameri- and Brunswick Phonograph Companies outsider appears to have what amounts WHILEcan Telephone and Telegraph which will be heard from the Radio Cor- to a monopoly in the control of the per- Company that the largest of the WEAK poration group of stations, which will pre- formance of copyrighted music. And also wire tie-ups reached sixty-five per cent, of sent other opera stars. It looks like an to the outsider they seem to have exercised the listeners of the United States may be embarrassment of riches for the radio audi- that control in a most arbitrary fashion. viewed with the raising of an slightly ence. Whatever the internal politics Whatever the merits of the disputes be- doubting eyebrow, it is certainly true that among the broadcasters and however tween the two opposed parties may be, the new concerts of the Atwater Kent strong the grimly competitive spirit, the the situation now seems to be that the Company which began on October fourth listener is sure to benefit. broadcasters are unwilling to pay for a have jumped into immediate popularity license from the for the with a number of listeners. When the yearly Society great Learning, Via the Loud Speaker simple reason that they have no assurance Victor and Brunswick Companies broad- that they will be fairly treated from year cast their concerts last year, the radio who have a burning desire to to year. The broadcasters have taken the audience sat up before its assorted loud THOSEincrease their store of knowledge can sensible position (to use their own phrase- speakers and wondered if something new accomplish a good part of that end ology): "we desire to see that the writer hadn't happened in broadcasting. It had. by radio if they are so minded during the of the songs as well as their assignees The tone of all broadcasting was raised radio season now upon us. During the

shall be paid a fair sum. . . . Re- and it is our belief that it will never be last two years, many radio "extension solved, that the principle involved in the lowered. The first concert of the Atwater courses" have been offered over the air, reproduction of music by mechanical means Kent series with Reinald Werrenrath, one and the State University of Iowa was prob- now embodied in the present copyright of the best of American baritones, set ably the first higher educational institution law be extended to the reproduction of the pace for the rest of the series. Other to offer a regular air course, which was be-

music by radio. . . ." artists who will be heard in the thirty gun last year. Station wsui, 620 kc. (484 This means, simply put, that the listen- concerts, which begin at 9:15 p. M. Eastern meters) is broadcasting a course of lectures ers will benefit, for after the smoke of legal Standard time, on Sunday evenings, are on Monday and Wednesday from seven battle clears away, it will undoubtedly be among the foremost opera and music thirty to eight fifty P. M., Central Standard possible for more stations to broadcast stars of the world: Louise Homer, Edward time. On Mondays lectures on "Early much good music which is barred to them Johnson, Mabel Garrison, Maria Kurenko, Iowa History," "American Literature," now by the provisions of the copyright. It Salvatore de Stefano, Alexander Brai- "Iowa Flora" and "Population Problems" also means that radio is advancing toward lowsky, Leo Luboshutz, Charles Hackett, On Wednesdays wsui offers lectures on a firmer and sounder basis, for there is no Florence Austral, Albert Spalding, Benno "The Teaching of English," "Political doubt that the dispute over payment and Moiseiwitch, Toscha Seidel, Felix Salmond, Parties in the United States", and "Ele- copyright has hampered the arrangement Vincente Ballester, John Powell, Eva mentary Psychology." Actual university and presentation of programs. Gauthier, Anna Case, Freida Hempel, credit is offered to those radio listeners 180 RADIO BROADCAST DECEMBER, 1925

who complete the requirements of the course. Full information can be secured from Edward H. Lauer, director, extension Division, State University of Iowa, Iowa City. In Pittsburgh, station KDKA will resume its extension courses in cooperation with the University of Pittsburgh and the Pennsylvania State College. In Spring- field, WBZ is laying plans for another ex- cellent series of extension lectures. In Oakland, KGO, is broadcasting regularly to the grade schools of the city according to a very well worked out and ambitious plan. Throughout the country, educa- tional programs, most of them well planned out and presented can be regularly heard with little more trouble than a reference to the newspaper programs and the effort of revolving a dial.

Why the Farmer Likes Radio

early in its experience with radio in the of eco- broadcasting THE AIR COLLEGE FACULTY AT WSUI VERYnomic information, the Depart- At the State University of Iowa, Iowa City. A series of lecture courses, of college standard are ment of Agriculture proceeded on the broadcast from wsui throughout the winter, and college credit is given to those who comply with the that radio when es- theory broadcasting, requirements. Left to right: Edward B. Reuter, Frank Luther Mott, Bruce E. Mahan, Christian tablished as a regular part of the machin- A. Ruckmick, Helen Williams, M. F. Carpenter, Kirk H. Porter, Bohumil Shimek, and Edward H. Lauer ery of our present day living, would render a greater measure of service to the farmers than any other group or section of society," Department is firm in its belief that radio The experts of the Department estimate writes J. C. Gilbert, the Marketing Special- is a permanent fixture on the farm, as that there are 553,003 radio sets in use ist of the Department of Agriculture. "The strongly entrenched, perhaps, as the Ford. on the farms of this country, as against an estimated total of 364,800 re- ceivers in use in 1924. While most of us depend on radio broadcasting for entertainment and perhaps a bit of news, the farmer is growing to think of his radio set as a source not only of pleasure but of genuine profit. of the most interesting letters among a large number written by (Onethe farmers to show just what radio is doing for this interested class of listener was written by Fred Bu- chanan of Granger, Iowa who said:

As early as 8:30 in the morning we get livestock market report and from 10 o'clock on, grain reports. The market reports will revolutionize the farming business. The farmer gets the news about markets right off the bat he does not have to take the buyer's word for anything, and knows as much about them as the man at the principal market points. ... If everything in broadcasting is cut out, save the market reports, for they are bread and butter to us out here.

The increasing number of radio sets on farms, suggests the De- WEAF AND TWELVE OTHER STATIONS. partment of Agriculture, places a those who con- The "speech input equipment" of the Bell System at 195 Broadway, New York where the program, originat- responsibility upon ing at the WEAF studio is sent to the stations connected to it by wire. On some programs as many as duct broadcasting stations and thirteen stations as far west as Davenport and St. Louis are connected. At the control board shown, those who have information to dis- much of the wire is done. The second from the left contains the board on which the "routing" panel pro- tribute. When half a million farm- gram comes from the microphones in the studio. The small hooded lamps are speech amplifier tubes, ers turn a ear toward the which increase the strength of the energy before it is sent out by wire to the distant broadcasting station. listening The three switchboards at the right take the programs for the various wire lines to the Middle West. Two broadcasting stations of the coun- are maintained one wire for called the red and complete "set-ups" always broadcasting, layout, another, try, they expect to hear something the "order wire," so that instructions can go out independently between the control office and the various worth while. They expect the stations. If the broadcasting line should go bad, it is possible to swing in the "order wire" and so the pro- weather market gram continues without interruption. No other traffic goes out over the broadcasting wires contrary reports, reports, to regular long distance telephone practise, some lines carrying many other telephone and telegraph messages agricultural lectures, instruction DECEMBER, 1925 181

these days when spelling books are out of matter of dignity and high quality. The of is watched with some print. work WLWL being interest by listeners in the Eastern part EO FITZPATRICK, the "Merry of the country. Those who can hear the Old Chief" of the Kansas City Star station on its high frequency band are if not hear the station WDAF has left Kansas City and will missing a rare treat they do broadcast now be heard from WJR, Detroit. He was Paulist Choristers, frequently from this which is on the air be- the organizer of the phenomenally popular station, tween 8 and 10 p. Eastern Standard "Nighthawks" whose membership is said M., to reach 200,000. Time, on Sunday, Tuesday, and Friday nights. to WGY, now licensed to use NEXT50,000 watts on Saturday and Sun- broadcasting station is sched- ANEW for St. Louis which will be day nights, KDKA with a license to use as uled much as 10,000 watts is the most powerful sponsored by sixteen firms in that city, broadcaster in the country. There are the St. Louis Globe-Democrat, the Colin ten jooo-watt stations, WSAI, WLW, woe, B. Kennedy Corporation among them. It WCCO, WCBD, WORD, KOA, WOK, WHO, and will be a jooo-watt installation, located, as WEAF. Stations WGY, and WTAM follow is the growing practise, a number of miles with 3500 watts each, and KFI and KGO outside the city. This is the second large each, with 3000 watts are next in power station to be installed by a group of busi- LOUIS WILEY rating. Station WTAS and WJR-WCX use ness interests and operated cooperatively of was Business Manager of the New York Times who 2500 watts. There are now three stations by them. The first station this kind "The recently spoke over WMCA, New York. employing 1500 watts, 25 using 1000, and the excellent wcco, Minneapolis-St. Paul. in on daily newspapers published English seven with 750 watts. Nashville, Tennessee, has a new station, Manhattan Island," said Mr. Wiley, "exclusive WSM, which took the air early in October of trade newspapers, have the astounding total on a of 1060 kc. daily circulation of 4,039,286 copies. The present conductor of this depart- frequency (282.8 meters). twice the number of total is approximately THEment is relinquishing his duties with families in the entire district. metropolitan of RADIO BROADCAST because IS that has not even our this number IT reported Liberty bought There is no other cohesive force, ' of his duties in other the erstwhile WTAS at Illinois schools, which is so important in the life of our heavy departments Elgin, community as the newspaper." of the magazine. His successor, Mr. John and will soon come on the air with its own Wallace, of Chicago, a writer and critic programs. It is to be hoped that the pub- of more than ordinary ability, will continue lishers of Liberty will be enabled to present on various from their subjects agricultural "The Listeners' Point of View" in the programs of a better type than WTAS and stations. The colleges experiment January number. The mental level of WTAS is best indicated Kansas State College at Agricultural by their slogan, "Willie, Tommy, Annie, Manhattan, Kansas, station KSAC, ever new station, WLWL, 1040 kc. (288.3 Sammy." The writer defies any one to in broad- since 1923 has taken the lead is THEmeters) operated by the Paulist Fath- distill sense out of that. Liberty owned casting air courses for rural residents the ers, in New York went on the air with its by the same group which publishes on agriculture, engineering, home econo- first program not so long ago. A frankly Chicago Tribune and the new station, WLIB, mics, and general science. Those who stations in religious station, operated by a branch of will thus join WGN, making two have heard the lectures in these excellent the Catholic Church, its first programs the Chicago area owned by the same in- courses will that are well worth agree they have been all that one could ask for in the terests. an hour's listening.

'Broadcast Jftiscellany

IS sometimes fortunate that the radio ITartists do not hear all the remarks well intentioned enough for the most part made by the radio announcers. It was only the other night that a soloist failed to appear at a certain large station. "However," vocally beamed the announ- " cer, Mr. Edward Gumph, a very depend- able artist, will entertain you." Memo for the desk pad: "Be sure to tune-in radio to-night to hear "dependable artist."

publicity man of WNYC was doing THEhis best to drum up interest on paper about the broadcasting of recent munici- pal election returns from the station. Quoth he, "The first official election figures available will be heard from this station, since it will operate in conjunction with the Police Department. As votes are counted at the poles, each district reports to its

Police precinct. . . ." Italics ours, or THE COON-SANDERS NIGHTHAWKS is it "our'n?" It is so hard to remember Frequently heard from station KYW, playing from the Congress Hotel in Chicago * 76. Salitbury Strtet, Bedford. England Or

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When the Stations Come Rolling In Reception Is Renewed for the Broad paritively Inexpensive Learning the Cut vy 73'f By EDGAR

E twirling dial has captivated the globe! The construction of a simple but radio reception, permitting, as it does, a imagination of the world and the efficient short wave receiver brings the much greater scope for their DX abilities. prophecy of the Arabian Magic whole world within range of the dial. The requirements to admission are few. THCarpet has been more than ful- When the stations come rolling in on The receiver used is of a much less elabor- filled, as we flit from city to city, 7500 kc (40 meters), our magic carpet is ate type than that needed for good broad- by a mere turn of our tuning control. The not delimited in its journeyings to the cast reception. Two tubes at the most are thrill of DX reception is still with us, but confines of a mere continent. We begin usually employed. Tuning is so sharp on its captivating novelty, strangely enough, at the remotest border of our broadcast DX the high frequency (short wave) amateur is already wearing off. range as the appetizer for an international bands, that but one tuning circuit is re- That the popularity of DX broadcast evening. First, it's England, France, Bel- quired. Another control adjusts regener- reception should occupy the center of the gium, Holland, Switzerland, Spain, and ation, which plays an important part in stage for so short a period in the interest Italy. Slowly, we move on as the radio short wave reception. There is nothing of the average broadcast listener is sur- night advances, picking our way through startling in the way of special equipment prising, when we consider the marvel of myriads of American amateurs for the needed. that scientific conquest. But it cannot foreign stations to which our short wave It is needless to describe in detail a suit- be denied that those who have tasted a receiver makes us host. Next, it is Brazil, able receiver, because extensive experi- season or two of DX are to-day concentrating Argentina, Chile, Alaska, Hawaii, as the ments are under way, leading to the de- in the search for better quality of tone shades of radio night advance westward. velopment of short wave receivers for the reproduction so that they may receive the In the early morning hours, New Zealand, needs of new recruits to this new field. local stations with truthful fidelity of re- Australia, the Philippine Islands and Simple receivers and small battery powered creation. The DX hound of yesterday is Japan reward our zealous dial twisting. transmitters will soon be described in the stickler for high quality of to-day. A diet fit for a DX king! RADIO BROADCAST, and these can be built Not that we those mo- at costs from to forget proud WHO "BOILED OWLS" ARE ranging $20 $50, including ments "when the stations come rolling vacuum tubes. These experiments are in," with the aid of a newly built receiver is it unusual, as the first inkling of being conducted at the RADIO BROADCAST when New York, Philadelphia, Pitts- NORfleeting time, to have the bright burg, Cleveland, Chicago, Minneapolis, rising sun break into our international " Atlanta, Hastings, Denver, Los Angeles, reveries and remind us that once more T WAS talking to a chap in Australia last night * Seattle, Oakland, Montreal and Mexico we must resume our daily tasks. For is not an uncommon report from a well equipped amateur radio in these short City were heard all in one evening! But such is the lure of the new DX that its operator days of wave, low The in even such accomplishments may become first tastes have led many a new recruit power transmitting. Navy, 1902 were over a record of established communica- commonplace. to sit attentive before his receiver the gleeful tion from Annapolis, Maryland to a ship off the To him, who would again enjoy these long night through. Such ardent devo- coast, 50 miles away. But to-day, even the thrills, we say, take heart, for short wave tees of the dial are rewarded with the lowliest amateur would consider a ^o-mile trans- amateur transmission and has honored title of "boiled owl" a reception fitting mission as nothing. Of course all this short wave us new fields to brought conquer, more designation for one whose long distance communication is accomplished by radio telegraph fascinating than the old. There is no work has been unexpectedly interrupted and one has to have a working knowledge of the exhausting the novelty of amateur com- by the rising sun. Increasing numbers Continental code in order to share the thrills of this work. But the code is not munication until we have established per- of broadcast listeners are being in- long distance learning sonal friendships in every corner of the trigued into this fascinating field of

HOW SHORT WAVE HIGH POWER A section of of a received at the Broad Street offices of the Radio of America from station at Sweden. tape, part" message Corporation SAQ Gothenburg, The message reads: Favor creditbank Oslo 2." The effects of static can be seen in several places appearing as a sharp .pointed mark much narrower ELL 416 Clcn \,,,,.^

""> ^ R.d,< k , ., \"" M 4J tf N I* r> ' net * ... ' ^ ' - TRANSMITTER v >i IK ij stisr RECtlVER " i i)-K ( 7 KM Cl . ' ' I-BGF i

LOUMS fK \VAiim-K u-i i. *< . "^Tafff- .AT VPU n d 111 SGI V- . .! PL Ot f i ilKKI M . kMP 'A I 1I '..,:,./';(; >*>/.-/,- / *< ai"'' "' ' " f. ; 1.1 ' ;' " DX ^R. S^T > ^'- "' tJch* OCM>UI-^ r fr^rti , ^ , ;. ,_ .--crrr' ^// S/

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Paradise for the DX Fan on Forty Meters the Thrill of Distance cast Listener The Apparatus Is Com- Code Is Necessary But Not Difficult H. FELIX laboratories with the cooperation of the the short wave. Among these stations are ters of amateur short wave history, pro- National Carbon Company. Nauen, Germany, POZ, operating on 15,000 ducing as it did convincing evidence to Amateur transmission is carried on kc. (20 meters); 2YT, Poldhu, England, naval officials of the practicability of ex- largely on a frequency of 7496 kc. (40 me- 12,000 kc. (25 meters); LPZ, Buenos Ayres, tremely long range transmission on low ters). Some stations work on about 60,000 8333 kc. (36 meters); i XAO, Belfast, Ire- power. The experimental station of this kc. (5 meters) and a great many others on land, 4997 kc., (60 meters); SFR, Paris, magazine, 2GY, communicated with NRRL 3750 kc. (80 meters). Another group, France, 4614 kc. (65 meters); WCM, Rocky while she was leaving Tahiti in the South employing radio telephony and continuous Point, Long Island, 4000 kc. (75 meters) and Pacific Ocean. Forty meters and five wave telegraphy, work on 1666 kc. (180 ROW, Moscow, Russia, 3614 kc., (83 meters.) watts of power were used at the Garden meters). A 7496 kc. (40 meter) receiver, Another service, which lends enchant- City end. however, gives ample opportunity for DX ment to the short wave territory, are Two difficulties of broadcast DX are not work because amateurs in all countries of special rebroadcasting links used to inter- encountered to a great degree in short the world where the contagion has spread connect chains of stations or to furnish wave reception. First, interference is min- are permitted entrance to the ether on or programs to permanent stations. The pro- imized because of the very much sharper about this frequency. grams of WGY are broadcast on 8570 kc. tuning on the high frequencies (low wave- KFKX, the of identi- WHO'S WHO ON SHORT WAVES (35 meters); Hastings, Nebraska, lengths.) Second, difficulty 5357 kc. (56 meters) and KDKA, Pitts- fying stations is greatly reduced because THERE are also other ethereal attrac- burgh, 4838 kc. (62 meters.) Oftentimes amateurs sign their call letters frequently tions available to the possessor of the these programs can be heard with great and freely. short wave receiver. Considerable com- volume on the short while wavelengths THE CODE: OPEN SESAME mercial transoceanic communication is the broadcast receiver is incapable of carried on by new experimental short wave picking them up on their regular broad- THE other hand, the broadcast transmitters, which may some day sup- casting channel. ONlistener must spend some patient eve- plant the immense high power, long wave The MacMillan expedition also used nings in learning the code, for amateur com- equipments erected prior to the debut of short wave transmission for code and radio munication is carried out by the dot and telephone communication, during its dash method. Not that this is a tremen- recent exploration voyage. Short wave dous undertaking, although the first few such a chore as it is commonly reported to be, and enthusiasts were privileged to hear the hours of code education are usually quite more than one broadcast li

RADIO MESSAGES ARE RECEIVED than the characters of the code. The Radio maintains Corporation several short wave stations, some operating on frequencies as high as 1 5,000 kc. as an <20 meters), mainly adjunct to their long wavelength stations. German and Argentine stations are also using short waves for telegraphic traffic 184 RADIO BROADCAST DECEMBER, 1925

into a few letters messages of considerable The letter G called in amateur parlance, oceanic radio stations, with their immense import and significance. A few samples the intermediate indicates him to be a and stately towers, overshadowing power of this esoteric language will serve to indi- resident of the British Isles. The prefix houses, and buildings filled with trans- cate the principles upon which it is founded. A indicates an Australian amateur; B, mitting and receiving apparatus, may hesi- Belgian; BZ, Brazilian; c, Canadian; CH, tate to believe that tiny miniatures of these First amateur: Chilian; D, Danish; i, Italian; j, Japanese; imposing equipments have sent their mes- CQ CQ CQ CQ CQ CQ UIAQR U I AQR M, Mexican; o, South African; PI, Philip- sage half way 'round the world. But the UIAQR UIAQR . CQ CQ pine Islander; R, Argentinian; Y, Uru- remarkable feature of short wave trans- CQ CQ UIAQR UIAQR UIAQR and New Zealander. The mission is the fact that minute Second amateur: guayan; z, only very QRA? means, "Where are you located?" power is required to set up ether waves UIAQR UIAQR UIAQR G2BAO G2BAO The answer of the first amateur consists which radiate for thousands of miles. G2BAO G2BAO QRA? of the usual acknowledgement followed by, an amateur in British Columbia First amateur: Recently location is (QRA without question maintained a schedule of trans- G2BAO G2BAO G2BAO UIAQR UIAQR "My regular mark) New Britain, Connecticut. Good mission and for fourteen succes- UIAQR QRA WALTHAM MASS GE OM reception evening, old man (GE OM). You are very sive with a radio-found friend in U VY QSA HR BUT QRM FM u6ciX nights loud here (u VY QSA HR) but I am having Australia, a five-volt WL WK U LATER HV 2 MSGS CUL using only receiving 4 73 from u6cix an American ama- OM interference tube, powered by heavy duty B batteries, teur on the Pacific Coast (BUT QRM FM for use with sets! Think Second amateur: designed receiving u6cix) I will work with you later (WL WK of it, you owners of five-tube sets one R R UR SIGS CD BUT QSS CUL u LATER). I have two messages for you receiving tube, efficiently used, is capable This seemingly cryptic communication (HV 2 MSGS 4 u). I'll see you later (CUL) of transmitting half way round the world. is pregnant with information and good Best wishes, old man (73 OM)." " SIMPLE APPARATUS IS USED manners. CQ is a general invitation to The reply means : I received your mes- communicate. CQD, the predecessor of the sage satisfactorilay. (RR) Your signals circuits used in these diminutive now universally adopted sos distress call, are good (UR SIGS GD) but they fade in and THEtransmitters are very simple. The is derived from CQ, the D being added to out (QSS). I'll see you later (CUL)." all-important thing is the correct arrange- signify "danger." Eavesdropping on short wavelengths ment and placement of high grade com- UIAQR is the first amateur's official call. has its fascination but almost invariably, ponents. In a characteristic way, RADIO The letter prefix designates him as a resi- it serves only as an introduction to the BROADCAST is leading the way to the new dent of the United States. The figure i creation of a "dyed-in-the-wool ham." field, by collecting data and designing indicates his location in the New England The term "ham" is used to describe the transmitters and receivers for the special district. The United States is divided owner of an amateur transmitting outfit. benefit of broadcast listeners. As rapidly into nine districts, each headed by a radio Possessed of a transmitter, amateur radio as the engineers conducting the RADIO inspector. AQR are the letters assigned to becomes a personal and living thing. It BROADCAST-Eveready short wave experi- this particular amateur by the Depart- is no longer an external world which you ments progress with their work, descrip- ment of Commerce. visit as an onlooker. You too can press tive articles will be printed in the maga- The acknowledgement of the second the key and become a part of the inter- zine, giving full details of construction and amateur consists of the first amateur's call, national dot-and-dash whirl. operation. followed by that of the second amateur's. Those of you who have seen giant trans- Although primarily a sport and hobby, there are serious aspects to amateur trans- mission. Feelings of sectionalism and nationalism vanish when personal friend- ships are built up between amateurs in the This is Station four corners of the globe. As the bound- aries of friendship have been extended 2GY through the ages by means of easy com- pnpral Headquarters munication and transportation, from tribe INTERNATIONAL to community, community to state, and RADIOBROADCA-ST TESTS state to nation, we have gradually acquired a unified national consciousness. Tribes no longer fight tribes; rivalries between cities, as that of Carthage and, Rome of old, no longer result in bloody warfare, as the telegraph, telephone, railroad and steamship have cemented friendships and demonstrated powerful common interests. Now we have short wave, low power radio, producing the citizen of the world, with friends whom he calls by name through the radio night, in Melbourne, Paris, Tokio, and Rome! If short wave radio spreads as rapidly as has broadcast- ing during its first five years, international peace will have a recruit and ally of signi- ficant influence. Predictions seem vision- but we need the TWO ESSENTIALS FOR AMATEUR TRANSMITTING ary, contemplate only influence of the telegraph and telephone, The regulations of the Department of Commerce, the Bureau in charge of radio in this country, which has lifted us out of in- are that for a transmitting station capable of sending signals outside of the state in which the set community is located, a license is necessary. The operator of the station must have a license also. The terest to a true national consciousness, to amateur station license is the long one in the center and the operator's license is shown at the right lend the color of realism to the hope that of that. There is no fee for either license and the examination is not difficult. Licenses are the seeds are firmly planted for a new recog- granted to those who can send and receive ten words per minute in the Continental code and who nition of international bond, established can pass a simple theoretical examination, dealing with the theory and operation of amateur apparatus through the agency of short wave radio! Plans for the Third of the International Radio Broadcast Tests

The First Announcement of the Tests Which This Year Will Take Place in January Cooperation in All Branches of the Radio Industry Will Make the Third Yearly Test More Successful Than Ever By ARTHUR H. LYNCH Director, International Radio Broadcast Tests

JOR two years, now, we have, during put in charge of the publicity and other From our experience during the last two the early part of the winter, had matters of a kindred nature. years, we have learned much and hope to an opportunity to listen to foreign Among those whose aid has been se- eliminate some of the difficulties by apply- stations with American broadcast- cured are Mr. F. N. Doubleday, President ing what we have learned. One of our ers off the air. Listeners in the far of Doubleday, Page & Co., who is now in greatest troubles was caused by lack of West have heard programs directly from England, where with the assistance of his accurate knowledge of what was being France, England, Spain, and other coun- friend, Rudyard Kipling, he hopes to ar- broadcast by the foreigners. This year tries. Our European neighbors have lis- range for the King to address a few words we hope to overcome this bothersome ob- tened to our concerts, and many reports to President Coolidge while millions of us stacle by having the foreign programs well have reached us from South America, radio-eavesdrop. in advance so as to be able to send them to Australia and, in fact, almost every nook Our Canadian friends, under the direction the press. We are going to arrange to and corner of the globe. of Jacques Cartier, who is in charge of the have to-night's program appear in to- But every effort which has been made in week for Canada, are also attempting an morrow morning's paper and in this way the past is to be outdone this year. Prep- exchange of greetings between the King make it possible for the listeners in any arations are now being undertaken to as- and his Western Dominion representatives. part of the country to make a check-up sure some very worth while features on the Radio organizations which for the last for themselves, instead of writing to us, programs themselves, as well as for the two years have been tolerant spectators, are or telephoning us from San Francisco or immediate check-up of the origin of certain now enthusiastic supporters of the Interna- Houston, to verify a program, as has been numbers broadcast, which will make it a tional Test idea and many such groups are the case heretofore. simple matter to recognize a station, even taking it upon themselves to see that the In the past, many imaginative listeners when the call letters cannot be understood. entertainment provided for our foreign heard all sorts of things, some of them The great difference between this year's friends will be of a superior nature. based on fact. This year we are going to tests and those we have formerly con- Nor are we forgetting about the folks arrange to mislead the misleaders by in- ducted, however, lies essentially in the at home. Even though the programs serting one or two false numbers in the period we have selected. The matter was are being specially designed for our foreign programs. These numbers will appear in put to a vote at the Associated Manufac- listeners, they will be of such high quality the newspapers, but will not actually be turers of Electrical Supplies Convention at as to meet the demands of the most sophis- played. Thus, when we get a report from Hot Springs several months ago; at the ticated dial twisters. some listener who claims to have heard a Radio Manufacturers Association Conven- The success of the tests this year is made number which we know was not broadcast, tion at Atlantic City; the National Radio doubly secure, because in Europe and we will see that his membership in the Trade Association Convention at New York America there are more high-power broad- Ananias Club be entered at once. in September; and a referendum was re- casters than heretofore, and there will be, For the serious listener, however, who cently taken by mail. In every instance by the time the tests are under way, a wants to enjoy the thrill of personal con- a the majority was in favor of the lat- direct short wave tie-up between our head- tact with many foreign nations within ter part of January, when receiving condi- quarters at Garden City and most of the single short hour, or the scientist who, by various tions would be better than at any other countries taking part. properly co-relating data from time during the year. sections of the world, Many of the trade taken during the associations have al- tests, a golden oppor- ready signified their tunity will be pro- intention of cooperat- vided. ing, and during the Months of prepar- annual meeting of the ation will result, this National Radio Trade year, we feel certain, Association, a fund of in European and other several thousand dol- foreign stations being lars was raised to heard in every corner assist in letting the of our country and public know about vice versa. Every International Radio listener in America is Week. Powel Cros- invited to take part in ley was re-elected THE COMMITTEE IN CHARGE OF THE TESTS these tests and assist

Chairman of Inter- Powel Crosley Jr., is at the head of the table; at his left is Arthur H. Lynch; others in the group in making them the include L. A. Nixon, second from Mr. R. W. Demott of Radio News, third from national Radio Week Crosley's right, greatest we have had Mr. Crosley's left; H. S. Fraine, of RADIO BROADCAST next to Mr. Demott on his left. Mr. and L. A. Nixon was thus far. George Furness of the National Carbon Company is in the right foreground An Improved Plate Current Supply Unit

How to Build a Universal B Battery Substitute Which Is Highly Satisfactory in Operation and Low in Cost The Parts Are Readily Obtainable A Description of the New Raytheon Rectifier Tube Which is the Essential Feature of This Device By ROLAND R BEERS

MUCH has been in |O published underlying the design of eliminators that unit using them will certainly surpass that the last six months with to regard are appearing this fall have brought forth of the home-made model. The photo- substitutes that the aver- B-battery new facts which are extremely important graphs, Figs. 4 and 6, show the construction broadcast listener is in doubt for the attainment of age high quality perform- of models employing factory parts. as to what type will give him the ance. Many weaknesses were present in THE RAYTHEON TUBE most satisfaction. It is natural that cer- the designs of last year's models: but the tain of eliminators will be of prevailing types research the last twelve months has 'T'HE very heart of this device is the suited for of * particular types receivers, succeeded in building up units of recog- new Raytheon rectifier tube, which while are unsuitable for nized and they entirely quality dependability. has been developed for this specific purpose. use on others. In order to make an in- The characteristics of this tube are quite choice these telligent between various de- revolutionary in their nature. the broadcast listener to signs, has had try In the construction of this tube, two out one after another until he has 30 Henries obtained anodes are provided, so that the tube satisfaction. Even after a comparatively rectifies both halves of the alternating he find thorough test, may that the short current wave. This feature is of first im- life of the rectifier elements will cause an 2-4 mfd 2-4 mfd. portance because it greatly simplifies the to that of B expense equal maintaining problem of filtering to obtain a pure d.c. batteries. supply. An additional feature made pos- It is the of this article to describe purpose sible by the small anode area is that it and construction of a FIG. I A the theory universal permits but a minute fraction of the current substitute excellent B-battery having oper- to flow during the reversed voltage period ating characteristics on all of re- of the types In the discussion given below, the reader current-flow cycle. Many rectifiers and an life. The ceivers, unusually long will find complete instructions and draw- operating on the gaseous conduction cost of construction will not exceed twenty- ings for making a B battery substitute. The principle give forth an extraordinarily general design is similar to that developed high "back current", as it is called, which by several manufacturers of new B battery substitutes that will be marketed this fall. 30 Henries Complete dimensions, list of materials, size and turns of wire, etc., are given for those who want to make up a complete unit 28 mfd. 28 mfd. at home. This construction can be very easily accomplished, but for the conven- ience of those who prefer to use factory- made transformers and choke coils, units FIG, I are described wherein use is made of these Two types of filter circuits. That shown in parts manufactured by the Acme Appara- Fig. i A is the "smoothing" filter popular in 1924 while the circuit, shown directly above, tus Company, General Radio Company, is the "brute force" or reservoir type so Dongan Electric Manufacturing Company, highly efficient and Jefferson Electric Manufacturing Com- pany. On 6o-cycle supply, any of these five dollars, and, as all parts are readily manufactured parts may be employed with available, the entire unit may be con- excellent results, and the appearance of the structed at home. Several ad- vanced features are present in *3M the design described below. O INCE our September, 1924, number RADIO BROADCAST has printed the Battery eliminators gener- *J best and almost without exception the only material on chemical and tube- ally consist of three major ele- rectified plate supply units. The present article invokes nothing startlingly ments: A Transformer to con- new, but it does describe a new rectifier lube which should have a very wide appli- vert the 1 10 volt a.c. to supply cation and popularity for this type of service. The Raytheon tube, whose use is the a required voltages; rectifier described here, has no filament. This simplifies the step-up transformer wind- which converts the a.c. into ing, since no extra tap-off from that winding is necessary to supply current for a This unit is also a pulsating d.c. and a filter cir- filament. full-wave rectifier which produces a much smoother cuit which smooths out the potential supply than the other types and simplifies the problem of filtering the One the construction the in this unit is a irregularities of the rectified output. of features of of transformer the shield around primary of the transformer which effectively prevents any stray voltage into a uniform d.c. noises present in the power line from reaching the secondary and being com- Most of our readers are al- municated to the rest of the radio circuit. Such a device has never been described ready familiar with these ele- before. The problems of construction and assembly are unusually few. ments from previous articles THE EDITOR. in this magazine. However, the study and development DECEMBER, 1925 AN IMPROVED PLATE CURRENT SUPPLY UNIT 187 have been on test at maximum Another 'important feature Curve of B- Eliminator for more than hours, Regulation presented by the Raytheon rec- output 4000 Using Raytheon Rectifier and have not yet shown signs tifier is that it requires no power of deterioration. It is doubtful for lighting a filament. This 150 if the maximum life of these power very often demands a tubes can be determined at large transformer supply, the intermittent operating periods cost of which is an item of great such as they would receive in importance. With the use of the the ordinary operation of a cur- Raytheon tube, a complete B- rent tap. If they were not substitute can be made up in a or continued no than a abused by overload Dashed Straight Line Shows space larger heavy last Equivalent Regulation Without short-circuit, they should 50 duty B-battery. Decrease of Impedance in Tube for After a consideration of the years. Which Occurs with Increasing Load The operation of the Raytheon foregoing remarks, we may write tube in a B-substitute is unusu- a set of specifications for the ideal ally quiet. The reason for this is B battery eliminator of to-day: 10 20 30 40 50 60 that the gaseous discharge is en- OUTPUT CURRENT IN MILLIAMPERES HOW TO BUILD THE APPARATUS tirely enclosed. There cannot FIG. be any sputtering of the dis- 3 E WILL now proceed with charge which might occur if the w:the building of the elim- elements were exposed to the glass tube or this value is more than sufficient for the inator. Figs. 4 and 6 show the arrange- insulators. This act conserves the helium demands of most receivers. ments of the parts when the unit is assem- gas with which the tube is filled, and greatly The filtering problem in plate current bled from factory models. The basis of prolongs the tube life. supply units is usually one of high cost these models lies in the circuit diagram, a The operation of a properly designed and considerable difficulty. When the schematic drawing of which is shown in current tap employing the Raytheon Raytheon tube is employed, as it gives Fig. 7. The values of capacity, inductance, rectifier tube has unusually good charac- rectification of both halves of the a.c. wave, and resistance shown in this diagram have teristics. Some of these will be pointed the filtering requirements are much simpler. been determined after considerable inves- out in connection with tigation, and the builder will points previously explained. do well to adhere to these First of all, we have excep- LIST OF RAW MATERIALS REQUIRED quantities as strictly as pos- tionally good "regulation." sible. These instructions 6 Ibs. Silicon Steel 1.20 The impedance of the Ray- ? also apply to the construc- 28075. No. 31 d.c.c. wire 2.19 theon tube increases with tion of the home-made 12 ozs. No. 32 d.c.c. wire .94 load, causing an upward y-2-Mfd. Condensers 12.25 transformer and chokers curve in the load character- 1-0.5 Mfd. Condensers .90 described below. 2-0.1 Mfd. Condensers istic, in distinction to the 1.40 Dimensions for the trans- i Bradleyohm No. 10 2.00 usual straight line falling former used in this elimina- i Raytheon tube 6.00 curve that low volt- tor are shown in 8. The gives i Standard socket .25 Fig. age at full load current. i-io,ooo-ohm resistance i.oo reader will do well to refer The fact that the to pages of the Sep- output I28..3 640-650 voltage does not fall off as tember RADIO BROADCAST rapidly as usual obviates The prices quoted above are maximum retail prices. In some cases sub- for a general discussion on stantial reductions can be obtained from the costs the necessity of providing given. the proper method of wind- an excessively high trans- ing and assembling trans- former secondary voltage. formers. For the benefit of The lowered a.c. voltage is an important Here one tube does the work of two at a those who cannot secure copies of this contribution to the safety of operation of great saving in cost, and at a higher number, a brief discussion of the general the device. efficiency. As indicated previously, there procedure will be helpful. The current and power capacity of the is no back-current perceptible. Back- The transformer is made up of three coils Raytheon tube are sufficient to supply the current is a bad feature from a filtering of insulated copper wire wound over a greater majority of radio receivers. The standpoint, as it complicates the filtering core composed of a large number of strips current output is rated at 60 milliamperes problem, and heats up the choke coil wind- of No. 29 gauge Apollo special electrical at 1 50 volts and it has been found from ings often to an injurious degree. steel. These strips are carefully cut by measurements of the plate current con- hand from an old power transformer or sumption of large numbers of receivers that

RADIO BROADCAST Photograph FIG. 4 A compact model of the battery eliminator described here. Note the large con- densers which are employed in the filter circuit to insure a smooth d. c. output 188 RADIO BROADCAST DECEMBER, 1925

cnoKe j

Transformer

10,000 Bradleyohm t to _,- ^~ 100,000 ~v' //' ' H ^ Dhm I . VJY"^ ~^P^ 1 i-cl "^ ' mfd i^ 1 ! K 4i* i-* 'vn r" 4=^ K

i 2 mfd. i j 110 Condenser Volts A.C. r.j DC eter- ~"S J

Sjjl | c%^.-:rzrz^p ' ' " i " Ci J v Li'-Crj "---CU C3Si Bradley unit High Low 15,000 Ohms Switch"'

FIG. 5 A picture diagram and wiring layout of the eliminator whcse circuit is embodied in the diagram Fig. 7

from sheets of the proper material, and applied first over the entire length of the ends of the windings for terminals, before shaped into the forms shown in Fig. 8. winding form, and consists of 1250 turns the ends are brought out from the winding. Enough pieces are cut out to make up a of No. 31 enameled copper wire, with a Each terminal is tied in place in order to complete core of the dimensions given in tap taken out and insulated at the loooth prevent its being ripped from the coil by Fig. 8, when they are assembled and turn. Two layers of Empire cloth are accident. If it is necessary, thin strips clamped together in a vise to determine placed over the primary winding, then the of paper may be laid over each layer of if the required amount of steel has been two separate secondary windings are wire as it is completed, in order to insure prepared. All rough edges must be re- wound, each of which consists of 2900 turns smooth layers in the winding. When the moved, and the dimensions shown must of No. 32 enameled copper wire, These coils are completed, the outside is wrapped be uniformly attained. two secondary windings are insulated from with two layers of Empire cloth or heavy There are three windings on the trans- each other at the middle of the winding manila paper as a protection and an insula- former which are wound in place on the form by means of a rectangular separator tor. winding form illustrated in Fig. 9. The of .oio-inch fiber. This separator is cut The steel laminations are now inserted winding spool may be assembled on a long out after the primary insulation has been one by one in the completed winding, as stove bolt with nut and clamped in a hand applied, and is put in place by means of a shown in Fig. 8 and the transformer is drill, carpenter's brace, or in the chuck of a slot cut in one face of the separator. See bolted together. If it is not convenient lathe for convenience in winding the coils. Fig. 9. to drill holes in the laminations for the Some means should be provided for count- While the first secondary is being wound, clamping bolts, the builder may cut out ing the turns exactly as they are applied. the remaining winding space is tightly clamping plates from hard wood or angle If the ratio of turns of the hand drill is filled up with a number of strips of cotton iron. In such case, the bolts will pass known for one turn of the handle, it is a muslin or cotton tape, in order to prevent through the ends of the clamping plates very simple matter to use this factor in the wire from crowding the winding separa- at the ends of the core, instead of through counting the turns as they are applied. tor out of place. In all cases, insulated the holes therein. Fig. 1 2 shows the method Care should be used to obtain within one leads 8 inches long, of flexible stranded of clamping adopted by the author in pref- per cent, of the specified number of turns wire (six No. 30 d.c.c. wires twisted to- erence to drilling holes in the core. If the on each winding. The primary winding is gether are satisfactory) are soldered to the builder desires, he may put mounting

FIG. 6

A different view of the eliminator employing manufactured parts DECEMBER, 1925 AN IMPROVED PLATE CURRENT SUPPLY UNIT 189

Ll sary under the operating conditions. When 5 this has been accomplished, the clamping plates are secured as described above. The filter condensers, shown in Figs. 4 and 6 were procured from Tobe Deutschmann, 2 mfd 8 to 10 mid Cornhill, Boston, Massachusetts, and have -Ol passed themost severe operating conditions.

Resistances Rj& R2-15,OOOOhms They were subjected to repeated charging Reactance Coils Li 4 L 2 R -NolOBradleyohm 1 and at volts and TRANSFORMER Condenser C-0.5uld. discharging 700 d.c., FIG. 7 The circuit diagram of the entire eliminator unit. The trans- former at the left steps up the line voltage, passes it to the double-wave tube which rectifies both halves of the cycle. Thence it is passes to the filter where it is smoothed out into pure d. c. The resistances permit the tap-off of the desired voltages necessary to the operation of the receiver

brackets on the base of the transformer to aid in se- curing the instrument to the base board. NEXT, THE CHOKE COILS

choke coils, shown at L, and U, Fig. 7 are THEconstructed in a manner similar to that employed in the making of the transformer. Each of these coils will have an inductance of approximately 20 henries if care is taken in constructing and assembling the cores. All rough edges should be removed and the cores should be assembled in an orderly manner. The winding on each choke coil consists of 5000 turns of No. 3 1 enameled copper wire, wound in smooth layers with the necessary interleaving papers. The out- side of the completed coil is wrapped with one layer of heavy manila paper as a protection. The laminations shown in Fig. 10 are inserted in the completed wind- ings, and the entire coil is assembled in accordance with the description of the power transformer above. A piece of .ooj-inch paper is inserted in the air gaps of the choke coil cores, to insure the magnetic stability neces-

, Mounting Holes to Pass y,J Bolt-,

6 190 RADIO BROADCAST DECEMBER, 1925

3

, /ie ,- FIG. IO

Here are given all the specifications Material: No 29 g. necessary for the construction and Electrical Apollo Special assembly of the choke coil cores Steel. Required:Approx. 48 Pieces each Type Copper 10 oz. Steel 1!< U)S

2 9" _ %2 R.H. Iron Mach. Screws 4-RI- Required with Hex. Nuts Separate Spool Heads 0.45" - -H* +' -4 0.45" O.OlORed Fibre Strip 55 ,' 29" T- T 0.9"x 0.45

0.45 LAMINATION FOR TYPE B REACTANCE COIL

0.45"

ASSEMBLED REACTANCE COIL TYPE B

is controlled age by means of the switch shown at S, Fig. 7. The blade of this single pole, double throw switch is connected to one side of the 1 10 volt a.c. line; one lug goes to the loooth turn tap on the primary, the other lug goes to the full secondary terminal at 1250 turns. When the switch is thrown to the loooturn tap, the output voltage will be from to 30 50 volts higher than on the 1250 tap, depending upon the connected load. The Raytheon rectifier tube will ordinarily run at a tem- perature in the neighborhood of 200 degrees F. In case the cup should become red hot, there is evidence that the circuit is being overloaded. Although no permanent dam- age will be done, it is not advisable to continue this load for more a than few minutes. Continued overloading will soon saturate the cores of the choke coils and render them useless as filter chokes. In order to prevent the transmission of power line noises the through eliminator circuit, a coppershield has been placed between the primary and secondary windings, and thoroughly insulated therefrom. This consists of a strip of .oo5-inch cop- per carefully wrapped over the Empire cloth insulation, and extending within \ inch of the entire periphery of the primary winding. A flexible lead is soldered to the shield, brought out from the winding, and later connected to the ground ter- minal of the eliminator. All cores of the instrument should be connected together and to the ground terminal. The homemade unit should be placed in an iron or steel case which encloses completely the unit. In the case of the factory each units, part has been placed in an iron magnetic shield, and this is connected to ground to prevent induction of hum in the receiver. Another means for preventing the transmis- sion of line noises through the eliminator is the use of the buffer condensers, shown shunted across the mid-tap and outer leads of the of the secondary transformer, Fig. 7. These AS THE BROADCASTER SEES IT

CARL DREHER^,

Drawings by Fran\lyn F. Stratford

In Defense of Broadcasting

THE September issue of the American enlightenment. If you were the editor of a like George Moore, who used to say, according Mercury, under the rubric of his monthly tabloid newspaper, how would you like this to Frank Harris: "Attack me as you please; department, "The Theatre," Mr. George projectile: "A tabloid newspaper, you need slang me, but write about me. I'd rather INJean Nathan pays his respects to broad- not be told, is a newspaper reduced in size, have a libelous article than silence; indeed, casting in terms which will descend sense, taste, and decency." Mr. Nathan lets I think slander more effective than eulogy. If harshly on the ears of radio impresarios who radio off easy, comparatively speaking. you hate my books, say so, please, at length; were beginning to believe what their own Many broadcasters, unused to criticism that will get me readers." will publicity representatives write about them. along old fashioned football lines, roar As for me, I can discuss this subject in a let it at that. indignantly and go That serene and unprejudiced spirit. While I am nor Supporting the cheap magazines and moving attitude possesses neither maturity good a professional broadcaster and derive most pictures in their campaign to moronize the sense. If the critic has no case, what he says of my income from radio, my responsibilities writes Mr. we now have the will in like country, Nathan, time dissipate itself, gasolene are purely technical. I am an engineer and radio. The roofs of houses from the Atlantic vapor on a boulevard, and there is no need to I put out on the air what is given to me, just to the Pacific take on the aspect presently get het up about it. If what he says is true, as a telephone installation man wires up of so many sailless schooners. And nightly wholly or partially, we might as well let him equipment indiscriminately for crooks, phil- the front parlors of the proletariat resound rub our noses in it and then see what we can anthropists, theatrical ladies who drive to the strains of alley jazz pounded out by bad do about it. And criticism is adver- hotel orchestras, to lectures on Swedenborgian- then, Minerva cars on an apparent income of $35. ism by ex-veterinary surgeons, to songs about tising, and no one can tell me that broad- per week, and gentlemen of the cloth. The red hot mammas and Beale Street melancholias casters don't like advertising. In this they are gentle rain falls alike on the just and the un- vaudeville and to the by hard-up performers just, and I don't care what I broadcast. names of the notables who have just come It's no skin off back if the programs are into Reuben's delicatessen restaurant. my rotten. As long as the transmission is Where a few years ago, a family living in good, I check and the V.P. & G. M. the hinterland occasionally after dinner read get my smiles on me. for the benefit of a book or at least looked through an album So much of "Famous Masterpieces of Painting," it those spectators who might imagine that I presently glues receivers to its ears and is am moved in my defense of broadcasting into wild thrown aesthetic transports by to the extent that I feel called on to defend some Harlem coon's recitative on his Heimweh it by my need for Hungarian goulash and for Alabamy or some two-a-day De Pach- French pastry. mann's interpretation of Mozart on a saw. Mr. Nathan's indictment is true There are two radio broadcasting stations, enough, it he has one in New York and one in Philadelphia, alas, but should be added that that have made an effort periodically to give selected the holes in the cheese for his dis- their customers something better in the way cussion. There is considerable nourishment of music than that for its finest which, effect, in the solid portions. Among some 600 must be played on kitchen utensils and cow- broadcasting stations in operation in the bells and something better in the way of United States, at any given time, some will educational talks than lectures on hygiene be radiating respectable stuff, others will by press agents for new mouth-washes, but be a load of and I understand that they have found the going carrying aspiring sopranos rough and, in self-preservation, have been so-so material, still others will be engaged forced to fall back more and more on the in purveying aerial garbage for the listeners gibberish and caterwauling that the aerial who like that sort of thing. A cross- connoisseurs admire. sectional view of the burden of the ether Readers who have never before encoun- waves would show as great a variety in tered Mr. Nathan's mode of expression will quality as the same process applied to peri- observe that he does not deal in weasel odical publishing, say. If one. walked words. He makes it plain that no high- blindfolded up to the newsstand at the pressure salesman is going to sell him a corner of Sixth Avenue and Forty-Second 1575. radio set. Not that Mr. Nathan has Street in New York, picked out a magazine, anything against broadcasting in partic- opened it at random, and analyzed the pages ular. In the article from which 1 have exposed for ideas, the percentage revealed quoted he rends and tramples on the twenty would probably run even with the birth rate cent magazines, the movies, tabloid news- WHEN IN DOUBT, THEY WIELD THE BLUE among mules. And that newsstand, be it papers, and other such agencies of popular PENCIL noted, carries all the respectable magazines 192 RADIO BROADCAST DECEMBER, 1925

as well as the cash girl trade; at most magazine good taste than the average printed book over the radio, and at one point he remarked " stores the chances of lighting on something in or magazine, not half as disturbing to the same extemporaneously, For all 1 know a lot of the cultural Class A would be even less. If as the average city newspaper, and not one Polacks are listening to me." The comedian, you are after intellect and good taste, you quarter as flagrant as the average big time of course, had no offensive intention, but during must pick it out from amid the rubbish. vaudeville show or moving picture. As for the next few days he received twenty protests Likewise in radio. If you want jazz issuing the tabloid newspapers and other such dung- from Polish listeners, including a formal de- from your loud speaker, there are certain hill enterprises, broadcasting, with all its nunciation from a society. If I wrote a story wavelengths in every radio locality where you glaring faults, is positively a civilizing influ- containing some reference to an elderly Jew in a can get it at any time. If you want something ence; by contrast, its entrepreneurs and green sport suit, and there was nothing else the better, you may be able to get it if you have managers become so many Schopenhauers, matter with it, there would be no difficulty in learned to discriminate between stations. and Sidney Laniers. getting it published and receiving payment for You may not be able to get it just when you It is true that a great many silly and obvious it. But broadcasting that phrase, at the present want it. But there is just as wide a range talks get a hearing via radio, and that not a stage, would be out of the question. No pro- between the best and the worst broadcasters few of the lectures have an unpleasantly gram manager would touch it. In his audience as that between the most estimable and the sanctimonious and oily tone. The second of several hundred thousand there must be most trashy books or magazines. And, owing fault is caused partly by the influx of people several elderly Jewish gentlemen who wear to the vast and, perhaps, excessive amount quite without qualifications for radio lecturing, green sport suits, and he wouldn't make them of broadcasting, there is also a great variation who try to compensate for their deficiencies sore for the world. No one must be offended, with respect to time in the case of any given by slobbering over the listeners. On the other no one's morals must be impaired, a thousand station. In order to arrive at a fair judgment, hand, one hears more than a few people on the dignities must be tenderly preserved, the lecture one would have to assess a lot of broadcast air whose natural frankness and sincerity must be fit for everyone between the ages of material and to do far more listening than manages to get through to the orifices of the eight and eighty. If, under these conditions, the Mr. Nathan has either the time or the loudspeakers. Dr. John H. Finley is one content of the talk is also to be mature and inclination for, in all probability. As one of such engaging speaker; even if one does not significant, you have a large order. his customers in his present vocation, I agree with what he says it is pleasant to listen Even controversy is often frowned upon. should lament his engaging in any such to him. As for the content of the talks, it Admiral William Ledyard Rodgers and General

I a Augean task. But I, perforce, have done varies all over the map. have heard every- Tasker Howard Bliss recently broadcast debate something of the sort. In the last two and thing from an inspirational speaker (he broad- on "Shall America Arm for War?" under the one half years, equipped, gratis, with a very cast in a frock coat, incidentally) declaring, auspices of the Forum. The debaters did not fine receiving set, I have put in some 3000 "All the evils of the world are due to incorrect come to blows, no riots were reported, and the hours listening to my own stations and others. thinking," to a lecture on Whitman by such more thoughtful among the listeners spent a Some of the stuff was not fit to inflict on an a recognized authority as Prof. Emory Hol- profitable half-hour. The magazine next wanted ursine howler. Most of it, culturally, was loway, the reading of a story by Sherwood to put on the air a debate between Professor neither here nor there, like the columns of a Anderson, and performances of one act Osborn and Mr. Bryan on the subject of Evo- newspaper or the counters of a five-and-ten- Provincetown plays. lution. But this was declared to be "too cent store, it had nothing to do with learning The trouble with radio talks is mainly that the controversial" by all the station managers the arts, or civilized taste. It neither assisted owners and program managers of the stations interviewed. So it was not broadcast. nor came into conflict with these things. feel it incumbent on them not to offend anyone. Mr. Nathan's conclusion that jazz is the staple Some of it, the cream, required no apologies They are in a constant stew about "adverse radio musical diet does not jibe with my ob- to any one. For three summers, now, any one publicity." A few letters from irate listeners servations. There is a great deal of jazz on the who cared to tune to 600 kc. (455 meters) could give them the horrors. They run their stations air, and a few stations emit almost nothing else, hear the New York Philharmonic on the air two for advertising or good will, and as soon as but they are decidedly atypical. The average or three nights a week, absolutely "without any one looks at them cross-eyed their knees musical radio offering is rather something on concessions", as the management puts it, shake. When in doubt, they wield the blue the order of the Silvestri-Toselli "Rimpianto" to the popular taste for operatic selections, pencil, and any one who tries to please the whole serenade pretty and obvious. In short, the easy overtures, and the like. Having thus world is in doubt most of the time. In such sort of thing all dining room orchestras in big thoroughly sampled the etherial waves, and large audiences as those they figure they are hotels turn out. Some of the hotel "ensembles" emerged sound and articulate, I depose and catering to, there are thousands of inferiority are very good, incidentally. They broadcast " say that the average metropolitan broad- complexes ready to be triggered off. Eddie popular classics. If 1 have heard Mon coeur casting performance is no more offensive to Cantor once delivered a first-rate humorous talk s'ouvre a ta voix" once, I have heard it a hun- dred times. There is a lot of Old Black Joe-ing and Silver Threads Among the Gold on the air, but, after all, these are decent folk songs, ob- jectionable only when overdone. Down another " pegare college things like Rolling Down to Rio," and the bombastic "Invictus." Not over a

third of the total is jazz, and on top you have beautiful Lieder, the best symphonies, including all the Brahms, the tone poems (I have heard Don Juan on the air in its entirety seven times) and the Strauss waltzes. At one station in New York, for example, absolutely no dance music is allowed on the air until after 10.30 in the evening. All in all, not so bad. Such inventions as the motion picture and the radio telephone have cultural and artistic possibilities, which are rarely realized because, with a large initial investment and heavy oper- ating expenses, the only way to get a return on the money is to produce something attractive to the masses. The result is what we know. Only two copies of Thomas Hardy were sold in Boston in the six months from January i to July i, Mr. Nathan points out. Still, the movies could do something even for Hardy's art. Need-

less to say, I don't mean any such shameful bur- lesque as the movie version of Tess of the d'Urber- villes which appeared a while ago. But if I had a few million dollars, I'd make a moving picture of Hardy's The Dynasts and perform RADIO IS TRYING TO PLEASE ALL BETWEEN EIGHT AND EIGHTY it, serial fashion, a competent actor, to be DECEMBER, 1925 HOW OUTSIDE PROGRAMS ARE PICKED UP 193

selected by Mr. Nathan, intoning the lines, wire company then runs a twisted pair from a or grounded, a roar of noise would probably to the accompaniment of a first class symphony convenient terminal box on the nearest trunk, come in, although in the balanced condition the orchestra. 1 should do this, not to improve over housetops and streets, to the theatre in circuit might be perfectly quiet. But it is not the movies, which can go straight into the sewer question. This lead is called a "lateral." If sufficient to have the two sides of the line equal for all I care, but purely for the benefit of the the broadcasting company is leasing an adequate in insulation resistance. It is also necessary few who care for that sort of thing. The Na- wire system these laterals are normally only a to transpose or interchange the two wires fre- poleonic wars forming the background of Hardy's few blocks long. The expense of work and quently, so that induction picked up in one great epic, the transparent tentacles of the material is charged to the broadcasting company, stretch is neutralized in the next stretch of equal Immanent Will, moving irresistibly those great so it is wise for the latter to balance trunk costs length. On an open wire line running on cross- columns of soldiers wearing the expression against additional construction in order to get a arms fastened to poles, each pair of wires will of men in a dream, could only be portrayed in minimum total for the two. When the wire be transposed at, say, every tenth pole. Like- the medium of the cinema. is placed in the theatre, with a long lead left wise, in a cable, the various wires must be Similarly, some day, somewhere, a millionaire in a coil so that the broadcasting operators can "paired." "Twisted pair" is used, never with American Mercury tastes may endow a radio set up at a convenient point in the house, the simply a pair of wires lying side by side. In broadcasting station to disseminate material telephone or wire company's lineman calls a properly paired cable several miles long, a few which is agreeable to him. If so, I shall be up the station, using an ordinary portable hundred feet of "straight-laid" conductor will pleased to oil the generators for same, and telephone, and tests through. He rings the ruin the entire circuit for broadcasting purposes, to be counted among its listeners. Mr. Nathan station with a magneto, causing a telephone because of the excessive noise picked up. The might buy an eight-tube "super" on that remote relay to release a drop on the station switch telephone engineers put it this way: "A tele- to-morrow. In the meantime, radio is neither board, and says to the control operator who phone circuit balanced in all respects, including " as good as the publicity artists would have us answers. This is at the Criterion Theatre. balance to other circuits, is immune to inductive believe, nor as bad as Mr. Nathan has painted it. Will you test this loop?" The operator then interference." puts no volts on each side of the line through When trouble is encountered on wire circuits, a voltmeter to If the is it is hunted down the of Technical Routine in Broadcasting ground. loop properly by process "localizing." insulated the meter will read only a few volts, the On long lines it is necessary to use special tests Stations resistance in series with it being of the order of which show the distance of the fault from the The ends of the are then but on short local circuits the i. Wire Lines many megohms. pair testing point, short-circuited at the theatre and a continuity lineman simply cuts out a section and by pro- AST month, in our discussion of "Per- test is made to locate high resistance joints and ceeding in this way sooner or later reduces the sonnel and Organization in Broadcast- the like. If the line is in good shape, the meter trouble to one section. He usually knows the 1 ' ing," we took up in some detail the will read practically full voltage, the line resis- weak spots in each section here the wire runs responsibilities and functions of the various tance being negligible compared to the resistance through a damp cellar, and there it rubs against employees, program and technical. However, of the voltmeter. So far we have merely the a roof coping, and so on; and sooner or later he the bulk of the discussion was on the problem standard procedure which thousands of wire finds the particular spot which is causing the of securing programs, rather than broadcasting chiefs go through every day on telephone and trouble. them. In this issue we shall get down to the telegraph lines. However, a further test is now Of course no circuit of any length is ever actual business of putting the program material made in which radio standards are rather more exactly balanced, in practice, and in the presence out on the air. with all the technical preliminaries critical than those of the older services. The of very powerful inductive fields noise will involved. men on the line listen for noise. If they can inevitably be picked up. For example, nearby The technical staff, as we have seen, is divided hear any noise at all with an ordinary pair of lightning will register on the best lines; high into transmitter, control, and field divisions, telephones bridged across the line, they are apt tension leaks, power plant troubles, certain all reporting to an engineer-in-charge or chief to run into trouble during quiet intervals in the types of automatic and multiplex telegraph technician of some sort. These men work with broadcasting. circuits, will interfere on almost any loop near the announcers and the studio manager during Noise comes in from various sources, such as them. Even if a man has armor on, you can the actual broadcasting. First, however, we shall stock-tickers, parallel Morse circuits, elevator probably kill him with a sledge-hammer or an take up the technical routine which precedes it. motors, etc. Each of these machines has a elephant rifle. The only answer is to keep This technical routine, in many respects, is characteristic sound, and men who work on away from trouble-making types of service as not radio at all. For example, the testing of lines become familiar with the various types. much as possible. However, various devices, wirelines is no more characteristic of broadcasting Usually noise interference is due to some un- such as shielded, paired cables; anti-noise sets, than of wire telephony, but it is equally import- balance of the line. It is necessary to have which slow down electrical impulses to a point ant in both. Practically every large broadcast- the circuit accurately symmetrical, electrically, where they no longer interfere, have been used ing station finds it necessary to go after its about an imaginary reference line in the middle. with considerable success. Again, some types programs by means of telephone lines. These Fig. i shows this condition, the line terminating of interference clear themselves through the lines are in a few cases owned outright by the at either end in repeating coils, or 1:1 trans- cessation of business activity in the early evening. broadcasting company, but as a rule they are formers, with grounded midpoints. Each side Ticker noise encountered on a morning test leased from some pre-existing telephone or is assumed to measure 60 megohms to ground. of a certain circuit, which is to be used in the telegraph company. Lines are costly and one If, now, one side of the line should be opened evening for broadcasting, may be ignored if it does not generally buy them out- right, any more than one buys a railroad in order to commute. When the lines are leased from some public service corporation, they are usually maintained by the O ol owners. Such a system will con- O 60 tn^ohnw To Reid sist of certain trunks running O Mid-point Mid-point To through the principal part of the Ground (ground TrABsmiHer .Amplifier \ ^. town, possibly in the form of a ten-pair cable devoted exclusively O to radio, for it is important that these wires should not be subject 3 to inductive disturbances and that Repeating' should not in they interfere, turn, Coil Coil with other public services. A week or more before the time scheduled for broadcasting, the program department sends a list of projected field events to the line company. On a certain day, FIG. for example, a musical comedy is to Electrically symmetrical lines are necessary in outside "pick-ups." The diagram shows the cir- be broadcast from a theatre. The cuit used. The field amplifier is controlled by an operator at the actual point of broadcasting 194 RADIO BROADCAST DECEMBER, 1925 is known to come from certain financial houses or telegraph offices which close down at 4 p. m. In case of emer- the utmost care gency, it is sometimes possible to shut down must be taken to parallel, interfering circuits during the period avoid interference of broadcasting. by employees who Broadcast operators and the lineman who don't know what is work with them know all these kinks and utilize going on. The broad- them in their work. The organization chart casting lines should shown last month did not include a lineman be red-tagged and a among the technical employees, but as a matter special notice sent of fact, although this man is usually not on the around cautioning broadcasting station's payroll, he works in the all unauthorized peo- closest cooperation with the station staff and ple to keep away. is to all intents and purposes a member of it, and, Most telegraph and if he knows his business, no mean asset. telephone men have Regardless of previous tests, it is important little notion of what that every wire circuit which is to be used on a broadcasting quality certain day for broadcasting, should be tested is and they will some- on that day some hours before the event is times innocently scheduled. Accidents often happen at the last break up a circuit in minute. If the event is a very important one, order to get a little such as a presidential broadcast, or a major amusement during prizefight, if may even pay to have the lineman idle periods. At one around till the job is done on the air. For these station it was noticed occasions, also, it is quite necessary to have two that music coming or three pairs, one for broadcasting, one as a over a long line (some breakdown pair, and one for an "order wire." five miles) was curi- For ordinary jobs a single pair is generally ously tinny lacking THE WIRE CHIEF WENT UP IN THE AIR sufficient. The operators talk over it until it is in the lower fre- time to take the air, and use it for post-mortems quencies. This was is or afterward. Sometimes the wire simplexed just the opposite of what one would expect the body, and the way in which people talk about used for telegraph conversation during the suppression of the higher frequencies by the line them, all change with time. Not only do they broadcasting without interference between the capacity. The engineers were somewhat puzzled change, but they show a tendency toward poetic two functions. This is not very common in until one day one of them happened to be at the figures of speech, and many terms which we use local work, but it is the usual thing on long main telegraph office in the city in question daily in the most matter of fact way, if we stop out-of-town circuits, where the cost of the line and saw an idle operator plug a 6o-ohm telephone to examine them, show an interesting technical is so great that all its potentialities must be into the jack panel of the broadcasting station, and literary history. This is particularly the utilized. in order to listen to the music. The circuit case with radio terms, and I purpose to classify to one's Wire tests must not be left any mem- was one terminating in joo-ohm impedances, so and discuss some of these| now popular expres- ory, but a log book, as shown in Fig. 2, is kept, this low inductance was effectively by-passing sions in the light of their origin and history. showing the condition of the circuit at the time all the lower frequencies. The engineer sent Radio, contrary to the notion of many of its obser- tested, and who is responsible for. the a 2OOO-ohm headset down to the telegraph devotees, did not start in 1920. It had its period vations. office with a polite note to the wire chief suggest- of development in the minds of men like Maxwell, It is possible to have one control operator in ing that if the operators wanted to listen in they Henry, Heaviside, and Hertz, it was born three wire the station who is exclusively detailed for could use the high impedance telephones without decades ago, and it is now past its infancy. It line work, but the usual procedure is to have ruining quality on the air. But the wire chief, has borrowed from all the older engineering so that takes a turn at the men rotate, everyone receiving this epistle, flew high up in the air, arts both words and ideas. If, as someone has it. Often the station is on the air in the morning returned the 2OOO-ohm phones with thanks and asserted, one can understand a thing only by the runs the control room and operator who apologies, and posted a notice informing his understanding how it became what it is, an at that time also takes care of the wire line staff that any one who plugged anything into examination of the technical jargon of radio tests for the day, since as a rule the observations those circuits without authority would be sum- should be as instructive as an article on hook-ups intervals are quickly made, and there are long marily fired. Then there was peace. and super-circuits and a little more out of the between tests while the lineman goes from one ordinary. In a station remote point to another. large Radio Lingo, Past and Present one operator may be "on the channel," as Physical Characteristics the saying is watching what goes out on the air in his writings or conver- and making necessary adjustments while an- sations Anatole France compares a syn- As in every field, the obvious physical char- other man handles the wire tests and does SOMEWHEREthetic language to a doll, while a natural acteristics of objects suggest suitable names. maintenance work in the intervals. language, with its centuries of use, growth, and We speak of cat-whisker detectors, bulbs, tubes, One point that should not be neglected is the development, he likens to a living woman. On condenser plates, plugs, knobs, etc. Position removal of all laterals not in use on any given a more modest scale, the technical terminology in space acts in the same way; aerial is the most trunk. Otherwise the laterals pile up, increasing of an art or science, as it reflects the achieve- prominent instance. The types of aerials are all the capacity of the line to the point where the ments and changes of years of effort on the part named in the same way: umbrella, harp, fan, higher frequencies are lost and quality of trans- of many men, takes on an almost organic mean- V, inverted-V, flat-top, inverted-L, and T. mission is adversely affected. These sections ing and color. We usually think of objects like In these cases the name, or the figure of speech, hanging on uselessly may also bring in noise. antennas and microphones as purely inanimate was suggested by the physical appearance. In a properly maintained wire system the trunks and lifeless, forgetting that they are the tools of Somewhat the same process occurs with in- are stripped of laterals at frequent intervals human aspirations and carry with them an eman- ductance coils. We refer to inductance spirals and that does not mean every few weeks. ation of human emotions. The names of these and helices, and to honeycomb, latticework, If the lines pass through telephone exchanges tools, and of the scientific ideas which they em- basket-wound or cellular coils where the criss-

FIG. 2

A typical test report made by broadcast operators on the condition of an outside wire used for picking up programs

LOOP NUMBER DECEMBER, 1925 EARLY TRIUMPHS OF "WIRELESS" 195

crossing of the turns results in a cellular struct- in which every ship has all it can do to take care to stay afloat six or eight hours almost everyone ure. This is the simplest and least imaginative of itself, but at least one has the consolation of might have been saved. The nearest ship was portion of radio philology. knowing that what man can do was done. the Carpatbia and it was she who sped 58 miles, Before radio got into the picture, a vessel could under forced draught, in three and one half Figurative Expressions burn up or founder with hundreds of people on hours, arriving at the scene of the disaster If to call an aerial by that name is an obvious board, and another ship near by might go on its at 4. 10 in the morning, to find lifeboats filled with procedure as well as a trifle out of date in those way oblivious of what was happening. There survivors dotting the icy sea. The dead num- instances aerial in where the has been taken out is no tragedy like an avoidable tragedy. bered 1635, among them Jack Phillips, the of the wet to share the rarified atmosphere It was in 1909 that through the intervention senior wireless operator, to whom the surviving with the vases and porcelain dogs on the Dutch of radio such a tragedy was averted. The 700 owed their lives, for it was his CQD and sos shelf of the living room the term antenna is White Star passenger steamship Republic collided calls that summoned the Carpatbia to the a step higher in the literary if not in the physical near Nantucket Light with the freighter Florida rescue. Other vessels, the Olympic, the Birma, sense. This was originally a zoological name, and sank some hours later. But before she went the Virginian, and the Baltic, were on their applied to the organs of feeling with which down she called for help on her wireless set, way, but turned around on hearing that the lobsters, cockroaches, and other noble animals operated by Jack Binns. That call, picked Carpatbia had already done all that human poke their way. No one who has seen an insect up at Siasconsett, Massachusetts and by various sailors in iron ships could do. waving his antennae around when in an un- other coast and ship stations, resulted in all the Great as the service of radio proved on this certain situation, confronted, for example, by passengers and crew being taken off the Re- occasion, luck and uncertainty played too great an angry housewife with a mop, could have public before she sank, and what would probably a part in what followed the collision of the ship overlooked the analogy with a crystal set owner have amounted to a loss of hundreds of lives and the iceberg. The Titanic carried an ade- striving to receive Los Angeles from the Eastern was limited to the six casualties which had quate transmitting set, with a day range of more coast. A radio antenna is, in fact, an artificial occurred during the actual collision. The than 400 miles and a night range which carried her feeler or organ of sensation. world sat up and took notice. Mafiy people cry of distress far over the sea, and yet she might or We speak of a "phantom" "dummy" who had thought of the wireless telegraph as easily have missed altogether the Carpathia, antenna, as used for testing purposes where merely an interesting scientific toy, changed the one ship near enough to give quick assistance. radiation must be suppressed. Another figu- their minds overnight. Some of them bought It was also rumored at the time that one rative expression in connection with antennas stock in radio companies, not all of it good. freighter, unequipped with radio, was even is "counterpoise" literally a counterweight Three years passed, with the number of wire- closer and might have taken off passengers applied to a network of wires beneath an an- less stations and activities in general increasing who could not find a place in the lifeboats and tenna, the purpose being to keep the electric rapidly. Then, once more, the aerial telegraph whose lives ended shortly in the cold water. field away from poor conducting materials, such played its part, effectively enough, and yet it was The fact was that the Carpathia's one operator, as dry earth, and thereby to reduce the losses not sufficient to obviate a great loss of life when H. T. Cottam, was going to bed before the of the transmitting system. It might really the S. S. Titanic, then the largest ship in the Titanic smashed her nose on the iceberg, and be called a "counter-capacity." world, sank 800 miles off the Grand Banks of it was only by chance, or, if you please, the Newfoundland, at 2 a.m., April 15, 1912, after intervention of Providence, that he stayed up The Memoirs of a Radio Engineer striking an iceberg. The Titanic was driving a little longer to get off some messages, and through the night on her maiden trip, trying to heard the Titanic's CQD into his head- VII buzzing make a record for the crossing (Those were the phones, at 12:35 in the morning. Cottam days of rivalry between British and German already had his coat off. Had he taken off radio gets the bulk of its shipping interests) when her nose crashed into a the phones and grounded his antenna a few publicity through broadcasting. Some "growler" of moderate size, but large enough minutes earlier, the Carpatbia would have NOWADAYSfamous opera singer performs for the to open the liner's compartments, so that she continued tranquilly on her course while 2000 radio, or the President delivers a speech, and the sank only a few hours later. Although the people were perishing 60 miles away. The headline writers get busy. In the pre-broad- accident occurred in midocean, many vessels necessity of a continuous watch by two or more casting era, maritime disasters in which radio were near, and if the Titanic could have managed operators was impressed on everyone played a part were the principal source of pub- ( To be continued) licity for the art. Of course, at that time there was a novelty about the whole business which has largely disappeared since, so that incidents like two stations exchanging messages over a distance of a few thousand miles, would get into the newspapers, while now no one pays any attention to them. But anything that saves human lives interests everybody, and it was in connection with accidents at sea that many people first heard of radio or had it called strik- ingly, often unforgettably, to their attention. It must be remembered that at this time, around 1910, communication with a vessel at sea was still a novelty. The act requiring passenger-carrying vessels making sea voyages more than 100 miles in length to be equipped with "wireless" was passed by the United States Congress in that year. 1 1 was not much more than ten years before that the first radio set had been installed on a ship. Along in the early part of the first decade of the Twentieth Century, it was still the usual thing for vessels carrying hundreds of passengers to leave land and not be heard from again till they reached their destination, or, in some instances, not to be heard from again at all. The sea swallowed them up, and that was all. After radio was introduced, such episodes became rare. Radio cannot prevent shipwrecks altogether, but a great percentage of them may be avoided by its use, and practi- cally always help can be summoned when needed. That help may be only partially effective, or it may arrive too late, for, unfortunately, men and ships cannot be transported with the speed of the ether waves, and there are storms and situations MARINE RADIO GAVE THE ART ITS FIRST PUBLICITY "ARL

A Gallery of Interesting Models of the RADIO BROADCAST "Aristocrat" Receiver, Espe- cially Adapted for the Phonograph Cabinet the High Quality Audio Channel is Assured by Resistance-Coupled Amplification

FIG. 1

One of the Phonograph Receivers described in RADIO BROADCAST for June, July, and August, converted into a RADIO BROADCAST "Aristocrat" by the addition of one tube and by replacing the transformers with Dubilier con denser and resistance units for making a resistance-coupled amplifier

FIG. 2

This is a bottom view of the receiver shown in Figs. 5 and 8. The filament circuit in this receiver has been somewhat altered in that j-ampere ballasts, one each, have been used in the detector and radio-frequency amplifier filament circuits. A half-ampere ballast is used in the first two audio tube circuits and another is used in the output tube circuit. Where six-volt tubes are used instead of the five-volt type, short pieces of bus wire may be employed in place of the ballast resistors as indicated at the left hand side of the illustration, where two such base connections have been made. It will be noted that FIG. 3 " in this receiver Brach resistance coupling units and Brach ballast resistors Another RADIO BROADCAST Phonograph Receiver converted into an Aris* have been used tocrat" by the use of a three-stage Muter resistance-coupled amplifier

FIG. 4

This RADIO BROADCAST "Aristocrat" was made by Radio Research Laboratories, New York, and they have incorporated some slight modifications of their own, which are to be commended. For instance, the General Radio variocoupler used in the antenna circuit makes it possible to compensate for various antennas without tap switch. The voltmeter has a multiplier in series as it is one of the double scale type. Victor coils have been used in the radio frequency unit, and they have been found very satisfactory. Two Pacent lo-ohm rheostats are employed, one in the detector circuit and one in the radio-frequency amplifier circuit. The latter makes a particularly good volume control. The entire assembly is an example of the kind of workmanship that any home constructor may accomplish if he will devote himself sincerely to the job FIG. 5

This is a rear view of the receiver shown in Fig. 8. The simplicity of the It will be noted that layout is brought out thoroughly from this viewpoint. the sockets extend far enough beneath the sub-base to allow wiring to be made at approximately the level of the socket prongs. The manner of fastening the sub-base and binding post strip to the Bruno bracket is very satisfactory FIG. 6 and very substantial A Phonograph Receiver using the National Regenoformer Kit and the Browning-Drake circuit with a Heath resistance coupled amplifier unit. A 199 tube used in the radio frequency part of the circuit to save current and facilitate neutralization

FIG. 8 FIG. 7 Another RADIO BROADCAST "Aristocrat" receiver. The panel itself is but 18 This is the under side of Fig. 6. The small resistance in series with the right inches in and there is of room left at either end. de' hand rheostat is used to reduce the current from the borage battery to a point length plenty Specially of coils for the "Aristocrat" receiver, made the American Mechanical where operation of the 199 tube is possible without overloading. The use signed by entire have been in this model and the movable tickler is a three-Sage resistance-coupled unit in receivers of this kind makes the Laboratories, incorporated a variable resistance. This unit with the and secondary wiring job a simple one. The arrangement illustrated in Figs. 6 and 7 is very replaced by primary radio coils is called a Clarotuner. Bruno brackets have been used neat and the performance of the receiver is such that we do not hesitate to frequency in and the sub-base has been made to our the Osborne of recommend it for those who desire a really good receiver for installation design by Company Massachusetts. their phonographs Boston,

Regeneration may be Obtained Either by Variable 'Tickler or Resistance Shunted Across A Fixed Tickler

Circuit Enclosed Herein Comprises Resistance Coupled f Amplifier which may be Obtained as a Complete Unit

Resistor be in the Audio ~l Separate Units may Employed Amplifier^ ' where the Complete Manufactured Amplifier is not used / **

.002 to .004 Determine by experiment, the necessity for the use of this Condense

FIG. 9 altered. were shown This is the circuit diagram of the RADIO BROADCAST "Aristocrat". Note that the connections of C3 have been They incorrectly for November. .5 mfd. condenser should in the diagram accompanying the constructional article on this circuit on page 30 of RADIO BROADCAST A filament control in each of the tubes be tried across the B battery, which may improve the tone. Amperite ballasts may be used for How to Use Meters in Your Receiver

The Meter is a Comparatively Inexpensive and Valuable Refine' merit How Meters Work and How to Use Them for Best Results By JAMES MILLEN

*OT a few broad- article might have an alternative title, "How to Get More Out of Your used. Should the needle that is what will Mr. Millen's cast listeners have Receiver," for exactly happen if suggestions fluctuate violently in both are It is to tell how a radio receiver is the idea that followed. easy enough for anyone operat- directions, the tube is very but meters are to tell the how the meters in a radio ing acoustically, electrically, required operator much overloaded and both B circuits are functioning. The addition of the proper meters to any set is neither Nif receiver, they are built in at and C voltages must be an inordinately expensive matter nor a very difficult one. The mere assurance all, are there forappearance and materially increased. that one is using his tubes at the proper filament voltage is enough reason for not for any good they may do the meters. the use current milliameler will installing In addition, of a plate MANY USES FOR in the of the METERS enabling operator register instantly the slightest distortion occuring in the audio circuit, after the set to use his receiver more fashion described by Mr. Crom in his article in RADIO BROADCAST for October. are also a number effectively. Of course, every- Mr. Millen's excellent suggestions can aid every home constructor and net a few THEREof other uses for meters body knows that a set will of those who have manufactured sets which they would like to improve. THE EDITOR. work without a meter, but few know how much the proper meters will help in obtaining economy and quality performance. A small voltmeter, connected in the filament circuit enables one quickly to turn the control rheostats to the proper point so that enough current is flowing

I 1

IT (Multiplier)

\*r\ Galvanometer tl * I "*!

FIG. I This diagram shows how a resistance and a current measuring device are employed to determine voltage through the circuit to heat the filament wire to insure emission of electrons in the proper quantity. This is one of the conditions for the production of good quality. At the same time, the fila- ment is not operated above its rated volt- age. This prolongs the life of the tube. When a tube is used with a very slight increase over its rated voltage, its life is greatly reduced. Depleted B batteries are frequently a source of noise and distortion in radio

- Galvanometer t

t DECEMBER, 1925 HOW TO USE METERS IN YOUR RECEIVER 199

RADIO BROADCAST Photographs

FIG. 4 There are a number of different concerns making meters for radio use. The products of Hoyt (Burton and Rogers), Dongan, Jewell, and Cellokay are shown

Another such meter is a wavelength or resistance is equal to the product of resis- that either the o-io, or o-ioo-volt scale frequency meter, but this too may be dis- tance in ohms and the current in amperes, may be referred to depending upon whether pensed with in the modern radio broadcast which, in symbols is E = IR. or not the multiplier is being used. receiver by the simple expedient of cali- Of course, it is not convenient to make Ammeters are also fundamentally galvan- brating the dials on the receiving set. even this simple calculation every time ometers, which would be burned out if a All of the meters referred to above with one wants to know the voltage of his heavy current were to be passed through the exception of the wavemeter are funda- batteries, so the manufacturers put a them. In order that they may be used mentally the same that is, they are special scale on the galvanometer which to measure heavy currents, resistances essentially galvanometers, or devices for reads directly in volts. Then they go are connected across them so as to "by- indicating current flow. If a voltage is to still another step farther and build meters pass" most of the current and thus let be measured, then a high resistance unit, having an inherent resistance of such a only a small fraction of the total current called a multiplier, is connected in series magnitude that, for voltages under say pass through the meter. This "by-pass" re- with a galvanometer and the combination 50 volts, the use of an external resistance sistance is known as a shunt and in the case connected to the source whose voltage is to or multiplier is dispensed with. For higher of the small panel mounting typeof milliam- be measured. This arrangement is shown voltages, such as B battery voltages, it is meters used for radio work, the shunt in Fig. i. A small current will flow generally customary for the meter manu- generally consists of a small piece of resist- through the resistance and galvanometer. facturers to take a lower voltage meter, ance wire contained within the meter case. The galvanometer will indicate the value such as one having of this current. Now, by means of one of a range of 10 volts the fundamental laws of electricity, it is and making a mul- possible to compute the voltage readily tiplier which will across the terminals A, B, Fig. i, as the give a range of value of the resistance, R, and the current 100 volts. The

I, are known. This, known as "Ohm's scale on the meter Law," says that the voltage across a resis- is then frequently tance due to current flowing through the a double one, so

FIG. *, External cased meters may be placed as shown on a previously built set. The voltmeter at the left shows filament volts, and the milliam- meter at the right indicates B battery consumption. Both are Weston meters 200 RADIO BROADCAST DECEMBER, 1925

( Home Constructor

The Second of a Series of Articles Each Complete in Itself Showing the Jaded Home Builder How He Can Use His Present Equipment to Make Valuable and Useful Measurements and Experiments in His Own Home

- By KEITH HENNEY Director, "1(adio Broadcast" Laboratory

IHERE can be little doubt that cated. It is a two-tube oscillator, one of audio oscillator described in the September radio is one of the most attractive the tubes working at broadcasting radio article, is an alternating current of small fields for home experiment that frequencies, and the other at a fixed audio amplitude which cannot magnetize the has ever offered itself to the frequency. Either tube may be used alone, cores of any transformers. Fig. i shows average layman. The ramifica- or the two may be operated together as a the usual method of testing open circuits tions of this specialized part of electrical source of modulated high frequency energy. with battery and headphones, as well as are so and so varied the correct method of the audio engineering many USES OF AN AUDIO OSCILLATOR using that "that tired feeling" of having solved oscillator as a tone tester. The jack in all is always far in the distance, and the example, the audio part of the the oscillator provides an outlet for the home experimenter, with inexpensive and FORoscillator referred to above is used in looo-cycle tone and a plug in this jack not too complicated apparatus, can ap- the Laboratory of RADIO BROADCAST for will have the alternating voltage across proach so closely to actual scientific the following purposes: its terminals. One terminal should go research that he cannot help attaining a to the receivers, and the remaining wires, 1 . Source of tone for testing open circuits. distinct of one from the oscillator and the other from feeling having accomplished 2. Tone for measuring capacity, inductance, something of value at the end of each or resistance. the phones, should go across the sus- the characteristics audio day's experiment. 3. Measuring of pected broken connection. instruments, such as audio-frequency transform- For a long time the Editors have been sure Capacity and inductance, as well as al- ers, loud speakers, etc. that there were many who felt they had ternating current resistance, are measured built enough receivers, but who still had a It is common practice among radio by what is known as an "impedance craving to construct something with their workers to use a battery and a pair of head bridge" which operates from a source of own hands that would work in some useful phones to test open circuits, and at times alternating current. The audio part of way. Tools accumulated through days of a dry-cell operated buzzer is used. For this oscillator is again useful here, and receiver building cannot lay idle; radio example in a receiver which is inoperative Fig. 2 shows how it is used in the Labor- junk collected during those same days, is due to a broken connection, the wiring atory. It is not necessary to have much always too good to throw away; experience may be traced until the break is found. power for work of this kind, and if extrane- in radio matters causes a yearning for more In testing audio frequency circuits in ous noises make it difficult to get proper experience and yet, to build one more which transformers are used, it is extremely balance on the bridge, a one- or two-stage receiver might be the breaking of the bad practice to use direct current for audio amplifier is connected to the bridge proverbial camel's back. What is the home testing. After such a test it may be and thence to the receivers. For example, constructor to do? found that the iron cores are magnetized in the Laboratory, the noise and vibration This series of articles, of which this is with the result that distortion occurs from presses, in action several floors below, the second, has been planned with but one when the amplifier is again placed in makes it difficult to obtain correct mea- object in view, to lead these jaded souls operation. In the laboratories of the surements, without the aid of the amplifier into a field where there is endless variety, telephone companies, where hundreds of shown in Fig. 2. and where each thing accomplished leads telephone transformers are used, it is A simplified form of bridge will be to something else. And for those who strictly against the rules for laboratory described soon in this series and, with the really want to know more about radio, assistants to "buzz" out circuits either aid of the audio oscillator, will enable the who want to find out for themselves what with the phones and dry cell or with a experimenter to measure his own induct- is going on behind laboratory doors, these buzzer. ances and capacities just as is done in articles will be written so that they will be The iooo-cyc!e tone emitted by the any large and well equipped laboratory. in some degree helpful. The This will eliminate much of the home constructor naturally fits (gst ; t&f cut-and-try method that is into the field of radio experi- now in order when the radio CT*O bow the home constructor can on in be has built the ment since he has already SHOW go radio after builder decides to make new * radio sets that to bint are satisfactory, is the purpose of these articles. The tasted the joys of building " " coils, or to try different sizes first What Is to Become of the Home Constructor? appeared in this magazine successful apparatus, and in of condensers to tune to cer- for September and has created a phenomenal amount of interest. Each of these this he has learned the tain frequencies. The way articles really gives a complete set of experiments and useful tests which may be bridge of electrical shown in 2 is made "feeling" equip- made by any experimenter who is properly equipped. The apparatus, most of Fig. by ment it at least, in the form of parts, is in the radio "junk pile" of almost every the General Radio Company. first in constructor. article is in the related The article, the Sep- Each complete itself, experiments are and By varying the tuning con- tember number, described a they have a very definite use in any one of a number of ways. Using the audio denser across the secondary of oscillator to test receivers and the radio oscillator to calibrate ex- simple piece of laboratory them, is, for the oscillator, notes may be use to radio dealers who take in their and service equipment that is efficient ample, of great pride repair secured varying from about departments. The uses of the radio oscillator suggested here are novel and in- enough to grace the best lab- 200 cycles to the natural fre- genious and bound to be helpful. Those who are interested in laying out a oratory, useful enough to make of the transformer modest little "lab." of their own will be interested in the suggestions given at the quency it worth while for one to which is around any end of this article. THE EDITOR. itself, usually build, and at the same time 5000 cycles. These tones inexpensive and not compli- may be amplified if necessary, 202 RADIO BROADCAST DECEMBER, 1925

and used to determine the characteristics manner. The relation between FIG. I of audio-frequency transformers as well frequency and the piano scale A source of pure alter- current is useful as the resonance peaks which exist in will be shown graphically in the nating in audio -fre- loud Methods of RADIO BROADCAST. testing many speakers. testing January quency transformers. instruments will be forks be these low frequency Tuning may pur- There is no danger of described later. Calibrating the oscillator chased from musical supply magnetizing the cores when such a tone source is not difficult provided access is had to a houses and a small set, say, is used. The battery musical instrument that is accurately those of 256, 512, 1024, and 4196 "click" method is dan- tuned. will enable one to cycles, any gerous. An Erla cru- Middle C on a properly tuned piano cor- calibrate an oscillator. ciform audio trans- former is responds to a frequency of 256 cycles per being test- USING THE RADIO OSCILLATOR ed in this view second, and is a good starting point for the calibration of an audio oscillator. The In the Laboratory, the radio tuning condenser should be varied until the sounds emitted by the piano string and the oscillator are the same. Other fre- quencies may be obtained in the same

part of this simple device is used for the following purposes:

1. Calibrate receiving sets. 2. Set receiver for a given frequency. 3. Measure the frequency of incoming signals. 4. As a separate oscillator for super- heterodynes. for 5. Source of radio frequency energy measuring losses in coils, etc. 6. Wavemeter. receivers. 7. Energy for neutralizing

As an example, let us suppose that a new receiver is constructed and we are FIG. 2 desirous of finding out what frequency the oscil- An impedance bridge for measuring induc- band it will cover. We crank up tance or capacity requires a source of alter- lator and tune the receiver to it. Noting current. In this nating laboratory arrange- the dial numbers of the receiver, we change ment, the modulated oscillator furnishes the the of the oscillator and again tone, and a General Radio Inductometer is frequency used as a standard of inductance by which tune the receiver. In this manner we the toroid is being measured. The other ap- paratus is a two-stage audio amplifier and telephone receivers for obtaining an audible balance. The picture diagram above shows how the apparatus is connected

RADIO BROADCAST Photograph DECEMBER, 1925 NEW FIELDS FOR THE HOME CONSTRUCTOR 203

1,500

1,400

1,300

1,200

1,100

1,000

900

800

700

600

500

400 204 RADIO BROADCAST DECEMBER, 1925

.00025 mfd. .00025 mfd. an experiment is completed. Added to the nuisance of such movement there is the likelihood that readings taken on succes- sive days will not check for radio fre- quency circuits are tricky affairs. The tools that are needed are no more than are required for constructing receivers, but, like the electrical equipment, they should be of the best make possible. A good drill, a pair of long nose pliers, a pair of cutters, and a long, narrow screw driver are vitally necessary. Added to these may 1,000^ Output be the usual wood working tools, such as a hammer, a saw, and a plane. FIG. 6 Electrically speaking, the home experi- menter should his collection of A method of tuning begin Output Coil the intermediate cir- apparatus by purchasing a good voltmeter Feeder Wire cuit connecting the and a good milliammeter. The meters oscillator and the may be of the Weston 301 type installed apparatus being measured in student bases, or corresponding meters 'uning Condenser made by Jewell, Roller-Smith, General Radio, etc. The voltmeter should have a

BROADCAST for February, 1925, page 1 101, WHAT SHOULD THE HOME "LAB" BE? range of o to 10 volts and an ammeter the gain of radio-frequency amplifiers may which will be found to have many con- be measured. SEEMS to the writer that there are two venient uses should read from o to 10 IT Many experiments are now being simpli- methods by which the experimenter milliamperes. This will read the plate fied in RADIO BROADCAST Laboratory for may carry out his work. He may have a currents of 5-volt tubes under ordinary inclusion in this series. A simple and regular place for his apparatus and for his conditions, and with some simple acces- fairly accurate impedance bridge will be work, or he may not. Naturally, the sory apparatus will enable the experi- described, methods of measuring the am- laboratory should be a fixed place, where menter to measure the constants of tubes plification of both audio- and radio- apparatus may be set up and not disturbed as well as to check up on the other ex- frequency transformers and the losses in until the experiments in progress are fin- periments that go on. coils will be explained, and among other ished. Such meters can be purchased for about apparatus described there will be a vacuum In this place there should be a work $10 each with base, and are the first equip- tube voltmeter with which many important bench and a laboratory bench, and the ment that the experimenter should possess. experiments can be performed. Wherever latter should be kept free for the actual Additional equipment will be cited in possible references to current literature work at hand. It often happens that a future articles. will be cited as well as to standard texts. certain set-up of apparatus will be used for RADIO BROADCAST Laboratory wishes Readers are invited to write of their ex- some time, for instance where one is meas- success to prospective home laboratory periences or difficulties or to state what uring the gain of radio-frequency amplifiers, owners, and will be glad to hear from particular problems they would like to see and it is a waste of time and energy to tear readers who are interested in the experi- treated in this series. down and set up the equipment each time ments described here.

RADIO BROADCAST Photograph

FIG. 5 A photograph of apparatus actually being used to measure the high frequency resistance of coils. The oscillator supplies the energy, a Weston galvano- meter, Model 425, measures the current flowing, and a Genial Radio Laboratory condenser and resistance box aid in the actual measurement. In this case the intermediate coupling circuit is not tuned, consisting merely of two very small coils, one coupled to the oscillator, one to the coil under test. Later articles will contain descriptions of simple apparatus which is capable of performing similar experiments to those described in this article RADIO BROADCAST ADVERTISER 205

Ozarka Senior Console 197.50

Complete with Tubes, Batteries and Speaker

If Your Radio is Bought Right It will be a Life-Long Pal

A LITTLE more time, a little more care in making the A Few More Men ** selection in the first tends to more place generally are Needed to lasting satisfaction. Sell Out of every 100 Ozarka's sold in speakers retail for $58.00 five tube Ozarka 1922 are not in the with built-in to only eight today speaker $64.00, up In a great many counties we have the hands of the original owners this solid walnut console design, $160.50. man we want. He is rapidly building up a does not include 17 out of each 100 permanent and profitable business of his own because he has an instrument that who have purchased later Ozarka Our nearest representative will will more than meet all competition. More than models in newer cabinets. If set an Ozarka in type gladly up your home, this, he is trained to back up his sales with there is a single Ozarka that is not in without any obligation whatever. He the kind of service that counts. active service today, we have never won't tell you what it will do he will Many well established Ozarka representa- heard of it. let you do all the tuning. With the tives started by giving us only their spare Ozarka must as you satisfy yourself, time their evenings. If your county is open Without the Ozarka Service in to distance, tone, volume, ease of you can do the same. of direct trained charge factory repre- tuning and selectivity. sentatives, such a record would not be The investment in cash is very small. The investment in time necessary for study possible. Ozarka service can be had More than this you will be very is considerable. It requires patience, but in almost Pur- today every country. agreeably surprised at Ozarka prices the results have enabled many men to get chasers in South Swe- out of the and time clock Africa, Alaska, selling as we do, thru our own direct salary class. den, Newfoundland, New Zealand, representatives, our factory selling Any previous sales experience is helpful and all receive the same Japan prac- expense is very low we give Ozarka but not necessary. We can and will teach tical service as those in United how to sell. Canada, purchasers the benefit of it. you States, Mexico and Cuba. Whenever you find the sign of the Ozarka long Where is there a value to compare Send for 84 Page Book distance goose, you'll find a man who with the one shown above - solid "The Ozarka Plan" knows Ozarka instruments perfectly. walnut cabinet (no walnut finish or This book is entirely too expen- veneer), imported English loudspeaker sive to be sent out on postal card If such service added more to your of a marvelous tone, five tube instru- requests. It will be sent FREE to any man who mails the coupon cost it be a matter to con- ment with 75 Exide price might ampere storage below and who is really anxious sider, but it doesn't. Quality for quality battery, 90 volts of Eveready "B" to improve his condition. Tell us about yourself ask for Ozarka you'll find Ozarka prices lower four battery, 5 tubes, aerial equipment all Plan No. I OOand don't fail to give tube Ozarka's with built-in loud erected and the price is only $197.50. the name of your county.

122 Austin Avenue B 122 Austin Avenue B Chirao-o Illinois Chicago, Illinois

Gentlemen: Without obligation send book "Ozarka Instru- Gentlemen: I am greatly interested in the FREE book "The ments No. 200" and name of Ozarka representative. Ozarka PlanNo. 100,"whereby I can sell your radio instruments. Name Name

Address City. Address...... City. Ask the Man County Who ...State. Wears this Button County .State...

Tested and approved by RADIO BROADCAST if 206 RADIO BROADCAST ADVERTISER

There's Economy : Now, I HAVE FOUND and Satisfaction A for the of Ideas and in these Valley units Department Exchange Sugges- tions of Value to the Radio Constructor and You will find both economy and satis- Operator faction in the use of the Valley B' to this department are welcome and those used will be Eliminator and the Valley Battery CONTRIBUTIONSpaid for at the usual rates, that is from two to ten dollars each. A pri^e Charger. of twenty-five dollars is given for the best idea used during each three-month Economy in the B-Eliminator because period. The prizewinner for the last period was announced in the November it stops forever the expense of buy RADIO BROADCAST. All manuscripts intended for this department should not exceed about three hundred words and should be Little consider- ing new B batteries. . . typewritten. ation can be given to manuscripts not typewritten. Envelopes should be Economy in the charger because it addressed to this department, RADIO BROADCAST, Garden City, New York. recharges your own storage battery at home overnight at one-tenth the TRACING RADIO NOISES switch blades to the switch block and was cost of service station charging. . . traced through applying test loads using satisfaction in both And because, by radio listeners have been led heater coils, although arcing was not visible to believe that certain using them, you need never miss a objection- to the eye. Thus, all noises present at this program on account of low or worn- MANYable noises accompanying reception time of day were eliminated. The remainder were out bat' caused by power-line interference, or heard during usual broadcasting hours, other from teries. neighborhood operated devices, such as code, sparking trolley wheels, and the advice, "if the noise ceases when the during heavy rain or snowfall were satis- antenna is disconnected, it is an indication factorily reduced to a minimum by various of outdoor interference," and as such, was methods which have often been described largely beyond the individual efforts of the and which will not be gone into here. set owner to control. This is not always A. H. KLINGBEIL, true. Ashtabula, Ohio A particularly bad case of interference, which had the characteristics of outdoor A RATCHET COIL WINDER interference, was discovered to be coming PREVENTS UNWINDING from the residence main switch and branch

terminal cabinet, which was located four- FTEN1 in the middle of the winding THE VALLEY B 'ELIMINATOR operates teen feet from the receiver, in the same of a coil, the hold will be released from ordinary light socket; provides room. O momentarily to straighten out the a steady, noiseless flow of B current The switch cabinet and receiver were wire, and as a result the carefully arranged installed turns of wire at a constant voltage all the time. on op- may sides of this loosen, and the work With there can never be de' posite it, any room, and the lead- has to be done over crease of or noises due signals frying in wire paralleled again. batteries. Volume is main- to low B the house wiring A method of im- tained. Reception is uniformly good. through the adjoin- proving the usual rear room at a is shown in For receiving sets of from one to ing winder, distance of five the sketch, i, eight tubes. Costs less at the start feet, Fig. for fifteen and an ordi- than wet B batteries. Costs less in feet, involving did not enter nearer nary ratchet type the run than dry cells. Much long to the switch than screw driver, which more sat- - ..., the width of the many radio experi- isfactory , room. menters have in than -' The a their tool receiver, Handle-' equip- both. five-tube neutro- Means for Restraining the ment. As shown, the Wire While -, dyne, with loud Winding handle of the tool is speaker, was ad- gripped in a vise, or justed until noises held stationary by

were loudest. The Wire other means. The time selected for spindle of the winder test was 2 a. m. is fixed to the barrel, when no interference and the ratchet is was encountered set so as to prevent from street cars, unwinding. A rat- regenerative sets, chet type of brace THE VALLEY BATTERY CHARGER is FIG. or neighborhood bit obviously has the only charger needed for all radio electrical devices. the same advan- storage batteries. Its correct 6-am- Disconnecting the antenna produced si- tages for this use, and the spindle is pere charging rate makes overnight lence. Replacing the antenna and oper- gripped in the jaws in the same manner as charging a possibility. ating the room switches, the noise was is the screw driver method. still in full volume. The best method of the wire The Valley Charger also functions present restraining Next, the residence main switch was while winding, may not be available to radio on socket. It takes about any^lamp opened, and the mystery was solved, workers, for which reason the restraining a dime's worth of current for an for the noises could be produced and made reel, shown in the lower section of the in average charge. Quiet operation. to disappear by closing and opening this sketch, will solve their problem. Most radio dealers handle the Valley switch. Make this up of four ordinary spools, B- Eliminator The continuous or used for thread. Mount these on and Valley Charger. "crackling" "frying" spools one of noises, similar to that by bad nails or screws, so that the wire will feed Any them will be glad to produced show tubes, were caused by loose connection through with enough tension to make it you these units and explain screws of the main switch, branch ter- tight when wound on the coil. This reel their advantages. minal fuse blocks, and bad contact of plug will not only restrain the wire, but will also Radio Division VALLEY fuses. take out kinks and make it uniform and ELECTRIC Co. ST. Louis, u. s. A. of Branches in Principal Cities An occasionally loud "zip," or "buzz," even throughout the length the wound similar to nearby code interference, or coil. arcing of defective receiver jacks, was G. A. LUERS, Valley Electric caused by loose rivets fastening the main Washington, District of Columbia.

if Tested and approved by RADIO BROADCAST RADIO BROADCAST ADVERTISER 207

JVo Dials, JVoPanel, Built-in loudspeaker

Designed by R. E. Lacault, E.E., Chief Engineer of this Company, and formerly Radio Research Engi- neer with the French Signal Corps, Radio Research Laboratories. The Quiet Manner and

To protect the public, Mr. Lacault's personal monogram seal (R.E.L.) The Eloquent Tone is placed on the assembly lock bolts of all genuine ULTRADYNE rule of Model L-3 Receivers. All Ultra- UNOBTRUSIVENESS with sufficiency the good taste dyne Receivers are guaranteed as is the distinguishing grace of the ULTRADYNE Model L-3 long as these seals remain un- Radio Receiver. Ushers in a new era of radio reception a new, broken. easier command of the air's treasures. $135.00 A new artistic form of a radio receiver that blends happily with every scheme of interior decoration. Pleases the eye with itscharrning lines, its beautiful two-tone mahogany cabinet, its fine proportions. Has the appearance of a decorative tablepiece. Utter simplicity with superb receptive and reproductive qualities. Your local radio dealer will gladly give you a demonstration of this new modern receiver.

The Ultradyne Model L-3 is a six-tube receiver employing the fundamental principles of the best circuits greatly refined and marvelously simplified. No dials no panel; just two inconspic- uous levers, which constitute a station-selector. Volume adjust- ment the only other control.

Write for descriptive folder

MODEL L-3

PHENIX RADIO CORPORATION, ii6-C E 2 sth St., N.Y.

Tested and approved by RADIO BROADCAST 208 RADIO BROADCAST ADVERTISER

A COUPLING DEVICE FOR THE dependable, and ideas that are worth re- ROBERTS CIRCUIT membering are also worthy of preservation. By having a well-organized plan for SIMPLE device for varying the coup- systematically preserving and storing away ling between the tickler and second- the best ideas constantly appearing in the A ary coils is presented here for the ben- pages of magazines one does not have to efit of builders of receiving sets using the depend upon memory, since an idea-file Roberts circuit. This device provides a will always keep them on tap, available at a go-degree coupling, or less, with a 180- moment's notice when you want them. The degree turn of the dial. The rotation may necessity of having to remember where be in either direction to provide the same you last saw such and such an idea, and effect, and the dial may be turned more having to spend a lot of unnecessary than one revolution without altering con- time trying to dig it up is obviated by ditions. the use of a good file. From Fig. 2 B, it may be seen that the The idea-finder saves you this an- noyance and bother. It also saves time and labor, for if you have filed away your material for safe keeping, it is always go- ing to be on hand, right at your finger tips, ready for instant use. Good ideas are always finding their way into print. Plans are Carol being constantly evolved by Dial others and heralded in the pages Far out hill and over valley of magazines. There is always into the homes of rich and a wealth of various kinds of in- poor alike come the waves formation at hand, simply await- that carry the glad tidings of ing collection, coordination, and the Savior's birth. Little does preservation in organized form. such an idea-store- it matter whether the set is By starting house can have within elbow of new and or you mahogany gold reach the most useful data that of humble cardboard coils. can be obtained from literature Tonal in the beauty amplifier of all kinds data which might is the one indispensable need otherwise, for want of assimila- for the real joy ofradio. Happy tion and organization, go to seed, indeed is the owner of be forgotten or neglected. Rauland'Lyric! As you read a magazine you can mark articles of particular interest which suggest fruitful ideas for future application, and index them in synopsis form on a 3x5 inch card, which is filed in a card tray, with alphabetic guide cards. These are arranged according to subjects in which you are vitally interested. Then again, you can clip these FIG. 2 articles and file them away, either in filing folders, or in a whole idea of the device rests in the use of a desk-book file, with pocket pages, an old brass rod bent as shown in Fig. 30, and a time bill file, or a work-organizer. Any of A New Gift slotted fibre block as shown in Fig. 2 E. these simple accessories may be obtained ^ The slot takes all the up-and- from a local sta- for Radio Listener up Every down motion of the bent rod and store at Two Rauland-Lyricsin this beautiful tionery holiday box (fully sufficient for any makes use of the side motion as small cost. radio Sec it at dealer's I Primary-, set). your the rod is rotated. Bending the If you want to rod at an angle of less than 45 de- put yourown ideas grees will produce a coupling of to work immedi- less than 90 degrees. The angle of ately, you scrim- coupling will be twice the angle to mage through which the rod is bent. your file and find The materials used are shown in data already in the sketches, which are self-explan- your idea-store- atory. The same materials and house which en- dimensions need not necessarily be ables you to carry used however. The fibre block is out yourown plans shown with square corners but effectively, and these may be bevelled off so that with greater assur- other positions of the tickler may ance of success. ALL-AMERICAN RADIO CORPORATION be obtained. The center lines of Or, your own ideas 4201 W. Belmont Ave.. Chicago the rod and block must coincide may start you on a to produce smooth operation. scouting expedition Dial CLARENCE J. FRENCK, for similar plans in Wauwatosa, Wisconsin. TOP VIEW the magazines to A which you regular- A FILE FOR IDEAS 4 ly subscribe, and so a new TRANSFORMER 45 open up T DEAS are elusive. They come i subject for further The Choice ofNoted Music Critics and go. investigation and * Some means should be found BRASS ROD Vil DIAM. 3^' LONG data-gathering. D for catching and using them. F. E. KUNKEL, Memory is short-lived, not always FIG. 3 Washington, D. C.

jr Tested and approved by RADIO BROADCAST if RADIO BROADCAST ADVERTISER 209

ZONE-8 wcx fowoc mfherafm ZONE-3 ZONE -7 ZONE-6 WJAR to WNAC WSB to WHAS ZONE-4 WFAAfo WOS WWJ fc> KDKA

ZONE -5 WFI io KGO ZONE-2 WORD to KFVG

ZONE- 1 KFOTfo 200 aw/ere

A Separate Circuit for Each 40 Meter Wavelength Band! WAVE- MASTER Standard Model Kellogg for 28 years makers of precision telephone instruments and of since radio has $125.00 equipment producers quality parts began Kellogg perfected a radio receiver worthy to bear the Kellogg name.

In the illustration we visualize this grees equal to 1/4 times around wonderful engineering achieve' a complete circle over three times ment. the station finding range of any other set. In the new WAVE-MASTER there are nine separate circuits All other radio frequency sets have one for each 40 meter wavelength variable capacity which must be band. Each circuit gives that max- tuned, usually with three different imum efficiency heretofore found dials, to balance with their in- in one short section of the only ductance coils. dials of ordinary radio frequency sets. Each circuit brings within The WAVE-MASTER'S induc- the range of the tuning dial a dif- tance is not fixed but variable and stations. ferent group of is easily and quickly tuned, with the one Station Selector to How wonderfully simple tuning dial, balance the fixed becomes! Merely set the pointer capacities. to the wave zone in which are you Write us for the name of your near- interested and in the desired WAVE- MASTER bring est dealer. We will also send on station with the single Selector dial. Brotvn Walnut Console request, a complete explanation of with inbuilt horn This remarkable tuning dial actu- the WAVE-MASTER circuit. $275.00 ally has a tuning range of 540 de- Ask for Folder No. 5-L.

Kellogg Switchboard & Supply Company 1042 W. Adams St., Chicago, 111.

Radio Dealers and Jobbers The WAVE-MASTER franchise, backed by Kellogg resources and our powerful advertising campaign, is most valuable. Open territory is being closed rapidly. Wire us, or get into Chicago, quick, and tec us.

nnH annrmrprl Kv T? 4nir 210 RADIO BROADCAST ADVERTISER

SUPER-HETERODYNE NOISES and a half hours per day. The trouble in this particular set was traced to a by-pass HAVE been troubled at times with a condenser of .002 mfd. size (of reliable peculiar sort of throbbing, spluttering make, probably damaged by soldering), and I noise which was sometimes accom- replacing it stopped the leakage. Another panied by a low whine which sounded as leak of this sort was located between the if it was under a strain, on my super- windings of one long-wave transformer in a heterodyne. super-heterodyne outfit. I tried almost everything to obviate The measurement by a milliammeter was trouble of this and inquired several radio not necessary to locate the leakage, it was men as to the cause without result, and made merely to show by calculations how was almost baffled. I discovered serious Radian Panels in black and Makoganite finally such troubles might be. Where the come cut in standard sixes all sets. it to for that was due corroded A and B battery B battery life is short in any set, the above terminals. test is certainly advisable. I used battery clips to connect to the CLAUDE SCHUDER, and when the all to Be Sure of battery clips happened Sumner, Illinois bite through the corrosion I did not get Lowest Losses the noise. "How simple!" the reader will probably say, but I will confess that A VARIOMETER TO TUNE ANTENNA it bothered me at times for two months Panels are most ef- CIRCUIT OF THE ROBERTS SET before I ran it down. RADIONfective in reducing surface finally I hope that this may be of benefit to some and noises be- A VARIOMETER can be used to re- leakage leakage other fan. cause are moulded from the /-\ place the two antenna coils, variable they I. T. SUGGS, f condenser, and switch, in the Roberts insulating material made to St. Paul, Minnesota. circuit. It is much to construct order for radio purposes ex- simpler than the standard arrangement, is easier to clusively. tune, as takes less CHECKING UP ON B BATTERY just selective, up space, and makes a neat and LEAKAGE panel appearance, there are fewer possibilities of losses. 1 f you are mechanically inclined, you can easily No. 2 Socket for new UX magazines are advising the use make a variometer. tubes with collar adapter of incandescent in series for old type tubes. No. 4 lamps The sketch, Fig. 5, shows the part of the same as No. without with the B to tube 2, MANY battery protect set that is changed. From the grid of the collars, for new UX tubes filaments, and to lengthen the life of tube and the exclusively. amplifying plus terminal of such to indicate batteries, by lighting up theC battery, the hookup is the same as in shorts. the original circuit diagram. Connect the When such a is used with a multi- lamp stator terminal to the antenna binding post. Tests after tests have proved The rotor goes to the ground post. Some variometers work better with the rotor that Radion insures lowest losses OB + -OB+ may terminal connected to the antenna and highest efficiency. Radion post and stator to the ground. Connect the Sockets, Dials, Insulators and Receiver Receiver terminal of the variometer that is connected Tubing have the same high- to the antenna, to the grid terminal of the resistant characteristics as Ra- amplifier tube as shown. Connect the dion Panels. They embody the -OB- -OB- ground terminal of variometer to the latest Lamp- developments in radio. A negative post on the C battery. A small Ask your dealer to show you the (WRONG) (RIGHT) fixed condenser of about .00025 mfd. will be needed in series complete line of Radion low-loss FIG. 4 probably with the an- tenna as parts. shown, otherwise the average variometer will not reach below 999 kilo- Send 10 cents for booklet, tube set having no by-pass condenser, or "Building Your Own Set" cycles (300 meters) when used this way, else a very small one, oscillations and howl- especially if you have a long antenna. It often result. The effect is the same as AMERICAN HARD RUBBER COMPANY ing is interesting to experiment with a variable using a B battery partly run down it adds Dept.C-12 11 Mercer Street New York City condenser in series with the antenna. resistance to the circuit. Therefore put a There have been Chicago Office: Conway Building many interesting sug- large condenser directly across the B bat- Pacific Coast Agent: Goodyear Rubber Co. gestions on improving the Roberts set and San Francisco Portland tery as shown in Fig. 4 B. If the lamp lights dimly when the set is turned on, of course a short circuit exists in the set and can usually be easily located. .00025 But the fact that the lamp does not light is mfd. no indication there is no B battery leakage in the set a small leak wouldn't pass sufficient current to light the lamp. So it is advisable, before home-made set is New No. 10 4-inch Radion Dial. Nine other any styles in several sizes to meet all requirements. put in use, and after making tests for shorts and remedying any found (a short would ruin the meter in the next test), to connect a high resistance voltmeter in place of the lamp in B. Turn up the rheostats, when a small deflection on the meter should result. ^Ihc Supreme Insulation Then turn the rheostats completely off and FIG. 5 Made to order for radio purposes exclusively the meter should read zero. If it reads even slightly past zero, there is a leak in the set which will run the B batteries down even the variometer will work equally well with AMERICAN HARD RUBBER CO. when the set is not in use. two or four tubes. A set in Washington, C12. 11 Mercer Dept- St. For one set checked this District of four New York City example, way Columbia, using dry cell showed a very small deflection, which, tubes, gave good loud speaker volume on Please send me your booklet for which I en- measured with a amounted to With two was close 10 cents in stamps. milliammeter, KHJ. tubes, KHJ easily only | milliampere. The set seven heard on head I Name required phones. logged seventy- milliamperes in operation, but because such five stations on a loud speaker in one Address a leak goes on whether the set is in use or month. not, this one would cut the B battery life JOHN L. LEE, in half where average use of the set was one Washington, District of Columbia. Tested and approved by RADIO BROADCAST RADIO BROADCAST ADVERTISER

For radio economy EVEREADY HOUR EVEREADY Radio Batteries are noted for their long EVERY TUESDAY AT 9 P. M. service and economical operation. They are made in Eastern Standard Time different sizes and types so that every radio user can For real radio tune in the "Ever- enjoyment, to eady Group," broadcast through stations enjoy the economy and convenience be had by WEAF New York WCAE Pittsburgh the to his receiver. W J A R Providence W S K I Cincinnati fitting exactly right Eveready WEE I Boston WWJ Detroit WTAG Worcester Minneapolis The five dry cell types of Eveready Radio Batteries wcco St. W F I Philadelphia Paul W G R liutTalo WOC Davenport are here illustrated and described to make it easy KSO St. Louis for you to decide just which will give the longest and most economical service on your set. A dealer near you sells Evereadys. Eveready Heavy-duty "B" Battery for four or more tubes

RADIO DRY No. 486. Extra-large Layerbilt. 45 volts. Vertical. Eveready's latest contribution to radio. The new Layerbilt construction which gives much greater service. Same size as No. 770. Price $5.50.

Eveready "B" Battery for one to three tube sets No. 779. Large. 2V/2 volts. Vertical. Especially adapted for Radiola 25, DeForest D-17 and Operadio receivers. Same capacity as No. 766, and suitable wherever variable No. 764 taps are not required. Price $2.00. Portable 22y,-volt Eveready "B" Battery for portable sets Vertical l Price No. 764. Portable. 22 /z volts. Vertical. For portable $1.75 sets where medium weight and size are permissible. Price $1.75. Eveready "A" Battery Eveready Columbia Ignitor Dry Cell Radio "A" Battery for all dry-cell tubes. V/2 volts. The dry battery used by vacuum-tube engineers in developing the dry-cell tube.

Evtready Eveready "C" Battery Columbia. volts. Saves "B" tone. Ignitor No. 771. 4^2 Batteries, improves "A" Price 60 cents. Battery, and the proven Manufactured guaranteed by dry cell jor all NATIONAL CARBON COMPANY, INC. radio dry cell New York San Francisco tubes Canadian National Carbon Co., Limited, Toronto, Ontario volts EVEREADY

No. 779 22'A-volt Radio Batteries Large Vertical - Price they last longer $2.00

Tested and approved by RADIO BROADCAST 212 RADIO BROADCAST ADVERTISER HOW TO ELIMINATE LOCAL for Christmas Part 2 A set of NA-ALD Some Practical Information Based on the Results of Colored Dials an Investigation on Radio Inductive Interference

T month's RADIO AST BROADCAST presented the first of two articles to be to dress radio *-' up your printed herein on the above subject. The information has been taken a little from very excellent pamphlet which has been specially prepared by the Radio Branch the Marine and Fisheries the Dominion Give 'em to and of Department of of of your wife Canada Government, and which is entitled "Radio Inductive Interference, Bulletin Number One." The get the benefit yourself! previous article was devoted chiefly to determining the source various of forms of interference while this concluding part fives much practical information for the elimination of the trouble once it has been found.

TXTHEN" fans first built radio sets, the womenfolk registered silent MEANS OF SUPPRESSING RADIO objection to their ugly appearance but INDUCTIVE INTER- sufficient insulation to withstand the voltage of they endured the clutter because radio FERENCE the line. These installations should be approved was such a and because novelty they by the local electrical inspector to ensure that soon over thought maybe you'd get CASES where electrical apparatus sus- there are no fire or accident hazards introduced the craze. pected of causing interference appears to be by the installation. INin good mechanical and electrical condition, It is important in the of these choke But scon as they saw your craze was a design it is very often possible to supply some means of coils that should have low distributed permanent obsession, they began ask- they electrical in the in order ing for better-looking sets. preventing surges, originating ap- capacity to prevent the electrical surge from paratus, getting out to the power line where passing through the choke coil by means of this The latest, up-to-the-minute advance- they would radiate and cause radio interference. capacity. ment in making a set harmonize with These electrical surges have the property of its is the CHOKE COIL surroundings represented by passing through condensers more readily than New Alden Colored Dials. They will through inductances. The method employed, A TYPE of choke coil recommended for make old set most attractive. To your in * therefore, preventing electrical surges from cases where the current is less than three the new set they will add the pleasing the lines traveling along power and thus causing is constructed to i. It qualities of color and beauty. amperes, according Fig. radio interference, is to provide a path to ground consists of a hundred turns of No. 18 double cot- The colors are Garnet; Malachite ton-covered copper wire in a single like mottled and white Green, green layer, wound on a fiber tube 3 Brilliant that blends marble; Tortoise, inches in diameter, \ inch thick. with color or in every combination; Leads are soldered to each end and beautiful Grained Mahogany. $5.00 a made from No. 14 flexible rubber- set, any color, in hardware, electrical, insulated braid-covered radio or department stores and in gift copper turn shops. wire, making one around the tube then through a hole in Give a set to someone in your family the tube and extending through and then all of you can enjoy their the inside of the tube. The Or here's a stunt. Leave this beauty! burrs are carefully removed from on the room table magazine open living the hole in the fiber tube so as not at this page, with a big pencil check to cut the insulation. End rings mark beside this ad, and see if the fam- or fillers are mounted at the end of ily doesn't take the hint and buy a set for you. If the wife of one of your the winding to build up the same radio fan friends asks you what to give diameter as the outside diameter her husband for Christmas, you might mention Alden Colored Dials.

Mail the coupon below if you'd like some free but worthwhile information on the New Colored Dials. ALDEN MFG. CO. Dept. B13. Springfield, Mass. Alden Processed

RADIO BROADCAST Photograph AN INTERFERENCE FINDER Of typical form. This was made in the RADIO BROADCAST Laboratory. One Duplex variable condenser tunes both loop and the R. F. secondary, which feeds into a crystal detector

ALDEN MFG. CO. in the form of a condenser filter to or drain off of the winding. These may be made of tape Springfield, Mass. Dept. 613. this surge. In order to make this filter more or a suitable size of fiber tube. The whole Please send me "What to Build'* it is often advisable to information together effective, introduce be- coil is then covered with five layers of Empire with on Na-Ald Colored information Dials. tween the line and the source of the disturbance cloth and then taped with black friction tape a which will make the trap, passage of the surge and painted with insulating varnish. Mounting more difficult. This trap preferably takes the lugs made of fiber are then attached to each form of a choke coil which consists of a number end of the coil. of turns of wire of sufficient size to carry the This coil should be mounted on a board required current without overheating, and covered with asbestos i inch thick and the leads Tested and approved by RADIO BROADCAST i RADIO BROADCAST ADVERTISER 221 ATWATER KENT

"But why he go?"

they struck oil on the Indian lands in Oklahoma WHENmany of the Indians became suddenly rich. One of Model R,$IZ them, anxious to begin his life of luxury, went to buy an automobile.

The salesman launched into a description of the car in detail. Technical term followed technical term in a bewildering stream. Finally the salesman thought his work was done. He produced an order blank and paused. "Now," he asked, "is there anything else I can tell you?" The Indian scratched his head. "Urn," he said. "You tell me: He no have horse. Model II, Jll Why he go?" Model M,$z8 We could give you a description of the Atwater Kent Radio Receiving Sets and Speakers that would fill hun- dreds of pages. But what would be the use? You would still judge Model 12 (without lubes), $100 Model 10 an Atwater Kent, as you should, by its performance. (without tubes), $80 We want you to judge it that way, to compare it with any other radio you are considering. By looking at it and listening to it, you will get some of its technical perfection. When you have owned it and Model 20 lived with it, will know how it is. Compact, $80 Model I9,f

Hear the Ativatcr Kent Radio Artists every Sunday evening at 9.15 o'clock (Eastern Standard Time) through stations:

WEAK . Neiv York WEEI .... Boston WCAE . . Pittsburgh WFI ) Philadelphia WGR Buffalo woe . . . Davenport

woo Detroit . . ^ alternating wwj .... WSAI. Cincinnati WJAR . Providence KSD .... St. Louis WTAG . . Worcester Model 24, $100 WCAP . . . Washington wcco . . . Minneapol:s-St.Paul

fricei the Write illustrated booklet Atwater Kent Radio slightly higher from for of Prictt t light fyhightr from th* Rockies and in Canada ivesty ATWATER KENT MANUFACTURING COMPANY Rotkitf wtit, and in Canada A. At-wattr Kent, President 4.726 WIS&AHICKON AVENUE . PHILADELPHIA, PA.

-^ Tested and approved by RADIO BROADCAST ^ RADIO BROADCAST ADVERTISER

soldered and thoroughly taped according to the time of the publication of this bulletin by the standard wiring practice. Another type of Department of Marine and Fisheries of the choke coil which Dominion of Canada Government, special ^^^^MI^^H^^ w '" be found emi- condensers having No. 14 rubber-insulated leads nently satisfactory suitable for installing without metal boxes, were for use in motor obtainable from the Radio Branch of the above lines, telephone Department, at cost. bell-ringing lines, etc., is that de- TREATMENT OF TYPICAL CASES scribed on page 438 IN MANY cases it is to make of September possible slight in the connections of the electrical RADIO BROADCAST, changes the in order to use some in the columns of apparatus causing surge existing apparatus as a choke coil and thus the Grid (and pre- pre- vent the necessity of adding additional choke viously in the May coils to the system. issue of 1924). It A series commutator motor causing a surge was originally de- by at the brushes have its leads scribed by Mr. Van sparking may reversed to reduce the radio interference. Where Dyck in his article For EVERY one wire is grounded, radio interference from entitled "Man- such a motor is sometimes reduced Made Static." by reversing Radio Set the leads supplying the motor, so that one of the brushes is connected to the ground side of the line and the field coil is connected to the live side A stunning piece of furniture that of the line. In this the field coil is used as restores order in the room where case, a choke. It may also be to a you have your Radio! No more necessary place cluttered table-tops, nor litter of , Friction Tape and equipment un- Varnished Cambric der-foot. End Ring -FibreTutw No unsightly RADIO BROADCAST Photograph horn in evidence, A PORTABLE INTERFERENCE FINDER either! This con- Consisting of a stage of radio frequency amplifi- sole has its own cation followed by a crystal detector. A col- lapsible loop will the loudspeaker, in- greatly improve portability possibilities built. It's out of sight, but with Non-Vibrant Ceramic INSTRUCTIONS FOR MOUNTING CONDENSERS very apparent Horn tonal SUperiori- The clearest tone pro- /CONDENSERS which will stand a test ducer on the market. ^-> -ioies. T?/-,-t*or it Uoo of 1000 volts d. c. be con- nas Made of special com- voltage may the highest -de- Position which defeats nected across an alternating current or direct ,- vibration. current circuit of volts or less. On circuits veloped type of 250 which are fuses of not more than unit. With horn built of protected by special FIG. I 15 amperes capacity, no additional fuse is re- non-vibrating,extra-hard,ceramic quired for the condenser. On circuits protected Details for the choke construction. It consists material. Produces clear non-vi- of one hundred turns of No. 18 d. c. c. wire by fuses of greater than 15 amperes capacity, a copper brant tone. on a three-inch tube separated cutout base and small fuse (of ap- not must be There's ample room for every- proved type) exceeding 15 amperes, installed between the condenser and each un- condenser of one or two microfarads capacity thing; space for largest A and B grounded power wire. Where condensers are across the brushes. This is shown in Fig. 3. wet batteries or battery elimi- not installed in metal boxes and are to be placed In cases where neither side of the line is for home natorrequired any set; on wooden surfaces, they should be mounted on grounded, a choke may be inserted on the line and for a too. big charging outfit, pads of asbestos at least \ inch thick, and these connected directly to one of the brushes, while Finished in mahogany, or walnut color. pads should be sufficiently large to extend be- the field coil may act as a choke in the other line. Dainty design of parqueterie on two front yond the clamps used for holding the condenser In this case it is recommended to use two 2- panels. Top, 38 in. x 18 in. Substantially in place. microfarad condensers in series and ground the the of a built; product 40-year-old furni- Where condensers are to be used on 550 volt middle point according to the diagram. ture maker. circuits, two condensers of the approved type In cases where it is not convenient to make The price, forty dollars, is for the complete must be connected in series between the lines connections with the brushes of a motor, the console and includes the loudspeaker horn and the common point may be grounded. In condenser may be placed across the line as near and unit. Thousands of dealers are show- such installations, the condensers are to be pro- the motor as possible, and a choke coil may be this artistic addition to home radio ing tected by 6oo-volt fuses not greater than 10 equipment. amperes in each live line, and both the con- Rear View Set Hooked Ul> densers and fuses are to be enclosed in a grounded metal case. Where the condensers are to be connected to two-phase or three-phase circuits not greater than 600 volts, one condenser may be connected from each live line to ground and installed with fuses in boxes as stated above. As these condensers contain wax, they should not be placed where they may be subjected to excessive heat. Condensers when connected to a circuit as stated above have no objectionable effect on the Prict, tlO circuit of or the operation any electrical appara- RADIO BROADCAST Photograph West of Koch Mis., t42.SO tus and do not consume they any power. FIG. 2 Windsor Furniture Co condenser connection across APPROVED TYPES OF CONDENSERS Showing vibrating contacts of a battery charger are now many condensers on the HpHERE* market suitable for the purposes detailed in inserted in the live line when necessary. See this article. Those chosen must be capable of the instructions above regarding approved con- standing a test voltage of 1000 volts d. c. At densers and the use of fuses.

r Tested and approved by RADIO BROADCAST -J RADIO BROADCAST ADVERTISER

The S. L. F. that doesn't "hog" panel space

For over a decade General Radio parts have been the universal stand- ards of quality. They have been developed by the same engineers who designed the pre- cision apparatus now used as stand- ard equipment in nearly all the lead- ing commercial and technical school laboratories throughout the entire world.

Since 1915 the General Radio Com- pany has supplied scientific instru- ments in ever increasing quantities to such prominent institutions as the General Electric Company, Westing- house, Bell Telephone System, and The principal objection to many Straight line Frequency con- the Bureau of Standards for use in densers now on the market is that they "hog" too much panel electrical and radio research. space; thus making it necessary to re-arrange other instru- No one company in the history of radio has contributed more in labora- ments on the panel or rebuild the set entirely to allow enough tory equipment than the General room for the scythe-like sweep of the S. L. F. rotor. Radio Company. The new General Radio type 374 S. L. F. condensers eliminate The same outstanding skill, mate- rials, and workmanship are embodied entirely all such difficulties. They occupy the same panel in General Radio parts for use in the space as the well known types 247 and 334 condensers and construction of broadcast receivers. no more. In fact be used with they may interchangeably Through the merits of design, per- those condensers since the mounting holes are the same. formance, and price General Radio instruments for the scientist or set- smaller rotor of correct and double the By using plates shape builder are universally recognized as number of plates General Radio condensers have a straightline the Standards of Excellence. frequency calibration curve without the mechanical disadvan- Every instrument made by the General Radio is tages encountered in the average S. L. F. with fewer plates of Company thorough- ly guaranteed. larger area. The assembly of the type 374 condensers with respect to bearings, soldered-plates, and correct spacings are the same as the types 247 and 334. For further description and prices ask to see them at your local dealer's or write for our latest Bulletin 923-R. GENERAL RADIO COMPANY 30 State St. Cambridge, Mass. GENERALRADIO Behind the panels of Better Built Sets"

Tested and approved by RADIO BROADCAST 224 RADIO BROADCAST ADVERTISER

The live side of a low voltage lighting circuit Internal combustion engine ignition systems may be determined by means of a test lamp con- may cause radio interference, but this is usually nected from ground first to one wire and then to of a very local nature. Such interference may be Cfjrtetma* the other. The lamp will light when connected considerably reduced by making the leads from from the live line to ground. the magneto or spark coil to the engine as short On the Air! Battery charger of the vibrator type may be as possible and running them in a grounded prevented from causing radio interference by shield, such as metal conduit or lead-covered Are Tubes in Your Shape? connecting a condenser of \ microfarad capacity cable. The frame of the engine, magneto, and across the contacts. This is illustrated all should be At Christmas Tide! Listen to sweeter vibrating shields, thoroughly grounded. "Christmas Carols" clearer chimes and in Fig. 2 on the previous page. In the case of Rotary converters sometimes cause radio more celestial music broadcast by the great battery chargers it is useless to put condensers inductive interference by producing a surge cathedral choirs throughout the land. which travels out both on the alternating and direct current lines. In some such cases it A Rhamstine* may be necessary to introduce choke coils into the alternating current lines and put condensers TUBE BOOSTER across the lines between the choke coils and the converter. Before putting these choke coils will renew your old in the alternating current lines, it is recom- tubes with all the mended to try the effect of condensers across the pep and freshness brushes as described for the case of of new ones. Just previously commutator motors. put them in the 2 Mid. Condenser socket and turn on 1000 Volts Electric oionators which are used for purifying the current do it the air in and for FIG. 3 large buildings bleaching pur- once a month it poses in flour mills, sometimes cause radio Method of connecting a large capacity con- will treble the life denser across the brushes of a small motor inductive interference by producing a surge of your tubes and which travels along the primary lines supplying better dis- give you the ozonator. and a tance, volume, across the mains, as it is necessary to make use tone as clear as a belt This interference may easily be eliminated by at all times. It will pay of the choke consisting of the wire and coil within two coils of the for itself in a few connecting choke cylindrical days. the battery charger, to prevent this surge from Works on any alter- type previously described, one in each of the out on the line. current 110-120 getting nating low voltage lines placed as near as possible to the Rhamstine'Ar volts, 50-133 cycles. It Flashing electric signs may usually be prevented matters not, whether ozonator. from causing radio interference by connecting Tube Booster you use 2OI-A or 199 Type Tubes. condensers of from 5 to 2 microfarads capacity

If Motor Fuses are Send no money check across the contacts of the circuit breaker. It is Large/than 1 5 Arnps. the coupon below pay less than 600 Volts - Inserts Only sometimes to add a choke Ampsfuses Here, on delivery. necessary, however, Ungrounded coil at the line side of the circuit breaker and also connect the condenser across the contacts of the

ft /* Eliminates -- 1 *** I circuit breaker. As the radio interference from B" Battery B Rectifier such sources the conditions of the depends upon Dotted Lines Show Addition installation it is necessary to make these few of Condensers Across Motor Generator Brushes experiments, as suggested above, in each case in or 1 order to reduce the radio interference most L ii---. n * effectively. '.' " ".' Sometimes the radio interference from a flash- ing sign installation is caused by sparking at the commutator of the motor which drives the FIG. 4 flasher. This be determined the may readily by Connection for two condensers in series across nature of the sound in the radio receiver and may the brushes of a motor generator. The position described for be remedied by the method dealing for extra fuses, if the motor fuses are larger than with interference from commutator motors. 1 5 amps., is clearly shown

Rhamstine* "B" Rectifier A List of Australian Stations Only Broadcasting Here is a complete list of Australian broadcasting stations now active in that country. It is not gen- (Tube not included) erally known that one of these stations, that at Brisbane, Queensland, can vie with some of the important liminatfS all your "B" Batt*ry troubles such as American stations as far as power is concerned, for they use 5000 watts. As will be seen by the list, recharging, dead cells, and chemical action. A three of the seven other stations use as much as 3000 watts. American stations are often heard in Aus- Rhamstine* "B" Rectifier will more than take the tralia, especially those ;..::aicl on the Pacific Coast. We are indebted io Mr. A. W. Watt, editor of place of a "B" Battery tt will give a continuous and uniform current year in and year out with abso- Australian Wirtless Weekly, for the appended list. lutely no trouble at all. Small, compact, good look- ing, endorsed by the leading radio manufacturers, and reasonably priced. You should have one. CALL WAVELENGTH POWER LOCATION FREQUENCY Send no money just check the coupon. IN KC. IN METERS IN WATTS Tube Boosters are Trade Boosters. DEALERS write for our attractive proposition. Sydney, New South Wales Farmer and Company Ltd. 2FC 26l 30OO New South Wales Ltd. 2BL Mail the Coupon To-day Sydney, Broadcasters, 857 350 5OO Melbourne, Victoria Australian Broadcasting Co. Ltd. 37" J. THOS. RHAMSTINE* (12) 3LO 809 3OOO 506 E. Wood bridge, Detroit, Mich. Melbourne, Victoria Associated Radio Co., Ltd. 3AR 789 380 JOO Please send me Adelaide, South Australia Central Broadcasters Ltd. 5CL 937 320 500 D Rhamstine* Tube Booster at $6 Perth, West Australia West Australian Farmers Rhamstine* "B" Rectifier at D $25 Ltd. 6WF by express C. O. D. subject to inspection. If I am 240 1250 30OO not entirely satisfied with the "B" Rectifier I will re- Hobart, Tasmania Associated Radio Co., Ltd 7ZL 769 390 5OO turn it to you in five days and receive a refund of the Brisbane, Queensland Government Radio Service 4QG 779 385 50OO full purchase price.

Name. . . The broadcasting from the above stations is usually divided into four sessions, morning, afternoon, early evening, and evening. The exact times of these sessions, taking jlo as an example, are as Address . follows: Morning, from 1 1 a.m. to 2 p. m.; afternoon, from ) p.m. to 5.75 p. m.; early evening, from 6 to 7.75 p. m.; evening, from j.i^to up. m., the program always concluding with "Cod Save the King." J. THOS. RHAMSTINE* The difference between New York and Melbourne time is fifteen hours, thus, when it is midday in New Radio and Electrical Products York on a Monday, it is 3 a. m. Tuesday in Melbourne. Appropriate allowances must be made when is made between time and States in west New 506 E. Woodbridge St., Detroit, Mich. comparison being Melbourne United time points of York, and also for Australian points west of Melbourne.

if Tested and approved by RADIO BROADCAST * RADIO BROADCAST ADVERTISER 225

THE PERFECT UNION OF ART ANO SCIENCE

DE FOREST AUDION \B the world standard in tubes. De Forest created the first successful radio tube, and his Invention made broadcasting possible. The De Forest policy o f a specific type tube for each socket Insures finer reception and greater distance. Price. $3.

DE FOREST F-5 AW A compact, powertu 1 set I n polished walnut that will bring joy to many a household. Gives rich volume, and has the capacity to separate stations positively so that you can pick the broadcast gems without Interfer- ence. Extremely easy to operate. Price (minus tubes, loud speaker and batteries) $90.

DE FOREST F-5 M A superfine 5-tube set in two color mahog- built-in loud and any cabinet with speaker ' concealed compartments for "A" and "B* batteries. A great distance-getter, with un- canny power to tune in and out stations at will, and gifted with splendid tonal quali- ties. Extremely simple to operate. No howling or hissing in tuning In. An unsur- DE FOREST W 6 passed value at $110. n F TVA TfifiA KC.E TYPE De Forest Radio Sets can be bought at prices ranging from $85 to $450. De Forest Genius now Humanizes Radio! But Tonal is Not All new and . . . dis- Supremacy CTy^ARVELOUS circuit, just dance, ripple sparkle clearly, . . Those brooding low notes, renowned C_X L perfected, reproduces flawlessly tinctly. musically! Elbert McGran Jackson, sculptor, never in are heard hand- the mellow, sort modulations of caught average reception, architect and painter, put into this distinctly as though from the next room. hand-carved cabinet the of voice and the wrought, spirit the human captures it is not an In the reproduction of orchestral music the radio, in design, in motif adap- hitherto elusive overtones of the of charm- full importance of the De Forest achievement tation of a phonograph. An image with the set- musical register .... tuning sim- stands out. For the first time you get the over- ing individuality, it harmonizes tones as well as the middle tones . . . the ma- ting of any home. plified .... a new ease in opera- roll of the kettle drums, the crooning self-contained not a tion .... all embodied in the new jestic One unit, everything of the bass the strident crash of the . viols, wire in sight, nothing to connect . . and and beautiful De Forest or W6 brasses and the of the cornets and W5 piping heraldry portable; move it any place! Only charm and trombones. A orchestra heard Radiophones. symphony beauty for the eye. over the De Forest or W6 stirs the soul. ^ ^> ^> W5 The artistic conical is an no of reproducer insepa- No incoherence, oscillating jumble its mecha- rable part of the cabinet and tonal The voice of radio is no longer flinty and me- noise in its every instrument, every octave, nism attuned to that of the Weagant tallic, but mellow, human and musical true value. A achievement'. peerlessly ma&ic circuit. There are two controls for thanks to the A. Wea- just tuning, development by Roy To the lover of dance music the De Forest and these operate on one dial, which makes gant, Vice-President and Chief Engineer of W5 or W6 brings more sprightliness, more the task of "tuning in" the De Forest Radio Company, of a new and normally perplexing beauties of syncopation . . . you should hear There are marvelous circuit. extremely simple. special power Vincent Lopez, Joseph Knecht, The Night tubes in the fifth and sixth sockets which can all it This ingenious circuit, and the joy or others over either of these in- if Hawks, any give you volume to flood an auditorium, means to radio lovers, makes its first public struments! the you desire it. And, at your fingers' tips, in the De Forest and W6 Radio- appearance W5 All the tenderness of song, every shading of means to tune in a far-distant station you of cabinet art worthy phones, masterpieces the soprano's voice, all the pathos of the folk want no matter how powerful nearby stations of a scientific development so outstanding. elements so much only song exquisite but elusive may be. So wonderful is the reproduction of tone in desired but lost in all practically present-day See the incomparable De Forest Wj and W6 the De Forest or W6 that only the presence are by these De Forest an in- W5 reception, captured at your De Forest dealer's or write for of the lovely instrument dispels the illusion master- masterpieces. teresting booklet describing these that the living artist is in the rooms. To that is broadcast, the De everything pieces in detail. Piano chords come to you with their full Forest Radiophone gives animation, life and RADIO CO., Jersey City, N. J. rich resonance true piano tone. High notes humanness. DE FOREST

9Ae Qraite& J\famt in'Radio

DEALERS IN ALL CITIES AND RADIO COMMUNITIES THE EPOCH-MAKING ACHIEVEMENT WHICH MAKES ORDINARY RADIO RECEPTION A THING OF VE5TERDA 226 RADIO BROADCAST ADVERTISER THE GRID

A Department Devoted to Solv- ing the Problems of our Readers QUERIES ANSWERED

1. WHAT IS THE PROPER METHOD FOR PLACE- 3. WILL YOU DESCRIBE A METHOD OF MEASUR- MENT OF COILS IN A TUNED RADIO-FRE- ING THE RESISTANCE OF COIL UNITS TUNED QUENCY AMPLIFIER? F. H. J. Houston, TO PREARRANGED FREQUENCIES? B. H. R. Texas. Utica, New York.

2. WHAT ARE THE PRECAUTIONS THAT SHOULD 4. WHEN I REPLACE THE 3-VOLT TUBES IN MY BE OBSERVED IN ERECTING AN ANTENNA SET WITH 5-VOLT TUBES, THE SET OSCIL- NEAR POWER LINES? LATES. WHY? C. A. C Buffalo, New York. T. M. B. Boston, Massachusetts.

COIL PLACEMENT IN AN R. F. AMPLIFIF.R right angle coupling between the coil units be employed. See Fig. 2. A receiver employing one or more stages It is most important that, in the construction of radio-frequency amplification, satisfactory of a radio-frequency amplifier, or a receiver con- INresults depend largely upon whether or not taining one or more stages of radio frequency these amplifiers are properly neutralized. Now, amplification, the tube sockets be so placed BE SAFE- neutralization depends upon several things. that the grid leads are as short as possible. The internal capacity of the amplifier tube must must be such balanced ; the to the tube the Fire Under- be wiring PRECAUTIONS IN ANTENNA ERECTION that no coupling effects are obtained; and the writers Radio Code calls other day a serious accident occurred for the installation of a in Waltham, Massachusetts, caused by THEa young man drawing an antenna wire lightning arrester where- across an electric power line. The fact tha* ever an outside antenna the line was insulated did not matter as his antenna wire soon cut through the insulation, is used. and thus the current was communicated to his Swivel - with Set Screw body. The problem of antenna installation has caused carelessness on the part of a great many FIG. I fans throughout the country, and it has been the cause of many fatalities. The following The Jewell " several radio-frequency transformers should be general Don'ts" relating to antenna erection so placed and located that there is no electro- are given in a paper by Mr. Clarence V. Purcell, Arrester magnetic coupling between them. It is this of the Boston Edison Company, for the benefit last point which we will discuss here. of those who would profit by the example of Most of us have had an to view the others who have been unfortunate to has been opportunity enough approved by inside of a neutrodyne and to observe the pecu- become involved in some needless mishap: the Underwriters (see their liar angle at which the coil units are turned. Don't run an antenna over or under any other At such a there is a minimum of wires an electric current of Certificate No. E-5403) for setting coup- carrying any sort, both indoor and outdoor in- stallations. It is mounted in an attractive brown por- celain case and is easily in- stalled.

Radio Instruments

ask your dealer for a Jewell 15-B Radio Catalog or write to us.

ling between the coils. This placement can be whether these wires be high tension wires, approximated by the home experimenter in his service wires, or telephone lines. own construction. Individual test must be Don't attach an antenna to any pole or tower made to determine the point at which satisfac- to which other wires are attached, or climb or neutralization is obtained in the to climb such or towers for Jewell Electrical Instrument tory regular attempt poles any manner. purpose. Company As an aid in obtaining the desired results, it is Don't run an antenna over or across any suggested that in the construction of a receiver public highway. 1650 Walnut St., Chicago, 111. the coil units be only temporarily fastened to Don't attach an antenna to any electric light, permit ready change and variation in the angle telephone or telegraph pole, even though no at which they are to be set. See Fig. i. If it is other wires are attached thereto. If using an Making Good Instruments not possible to approximate this angle, which outside antenna, always comply with the regula- for 26 Yean is about 55 degrees from the horizontal, or tions governing the installation of an approved if there is plenty of space in which to con- lightning arrester. Such a device is inexpensive struct the amplifier, then it is suggested that a and easily installed.

f Tested and approved by RADIO BROADCAST -f RADIO BROADCAST ADVERTISER 227

Radio Receiver

This new principle of radio is exclusive in the Valleytone

Set the dials of a Valleytone for any station you choose. Bring in the signals strong and clear. Then turn the dials or from the correct Appearance one point beyond back tuning. You merely diminish volume. The quality of the signals re- is mounted in a solid walnut The Valleytone mains the same. There is no incoherent babble of noises. cabinet, finished in two tones with inlaid gold stripes. It may also be procured in Turn the dials two or three points either way from the correct beautiful console models. Special Valley tuning. Your program is gone. tables with built-in loud speaker may be Such is in the It is due to the obtained for the cabinet model. tuning possible only Valleytone. potential balance method of preventing distortion and oscillation. . . a new principle for radio which is exclusive in the Valleytone 5-Tube Radio Receiving Set. The potential balance gives a balanced tone to the Valleytone. The results are an amazing clearness and naturalness of reproduction. If Valleytone Console you have never heard the Valleytone, a new experience in radio Model reception awaits you. The Valley Toroidal Coils make possible a selectivity not previously achieved. Stations four or five meters apart can be brought in clearly and distinctly one after the other whether they are distant or local stations. Before you buy a radio, hear the Valleytone. Judge it by results. Avoid regrets later by listening to the Valleytone now. Any table Valley authorized dealer will be glad to demonstrate the Valleytone for you. with built-in loudspeaker

, Radio Division, ST. Louis,u.s.A.

Branches in Principal Cities Valleytone Valley Valley * Receiving Sets Battery Chargers B-Eliminators Valley Electric TVH>H nnrl annrm R nin Rurn 228 RADIO BROADCAST ADVERTISER

Don't borrow your neighbor's antenna by attaching your lead-in to the far end of his wire. You don't know what he is doing and besides, antenna wire is cheap and serves the purpose far better. Don't attach your antenna to a kite. Don't use your telephone line for an antenna. Connec- tion to an electric light socket is not encouraged or recommended; light socket attachments are approved. WITH ONE OF THESE DIALS 3 MEASURING THE RESISTANCE OF COIL UNITS

is described a method whereby those having the proper facilities may measure HEREthe resistance of coils tuned successively ACCVRATUNE to several prearranged frequencies. M I C & OM ETE.K CO NT R OILS With the aid of a radio oscillator, a thermo- galvanometer and a resistance box, a curve, ACCURATUNE dials plotting resistance against frequency, may be x~V. not only enhance im- measurably the attractive Intermediate Coupling Circuit appearance of your set but they insure clear and pre- cise reception of programs, and with even those stations now so closely grouped on the lower wave lengths easily and readily segregated. This type rec- ommendedfor Neutrodyne FIG. 3 and Radio Frequency sets. Priced at $3.50 made from the several readings obtained. The circuit diagram for the layout is shown in Fig. 3. To measure the resistance of a coil, the pro- cedure is as follows, assuming that readings are A. J. VERNIER to be taken at 1500 kc. (200 meters) 1200 kc. (250 meters) 1000 kc. (300 meters) and so on, for meters T7OR use on every 50 up the scale to 545 kc. (550 Super-Heter- meters.) JT odyne and Regenerative Put the oscillator into operation setting its the A. of- receiving sets, J. frequency control at 1500 kc. (200 meters). fers a degree of tuning Couple the coil to be measured, Li, to the os- efficiency not usually as- cillator output coil \_2. This will cause a sociated with dials that sell deflection of the needle of the thermo-galvano- meter. Now the at this price. Beautifully by varying coupling between constructed of genuine Li and L.2, the galvanometer reading may be varied to one of the numbered markings of the Bakelite, the A. J. possesses meter scale such as etc. a dignity of appearance 20-40-60-70-80, Since the next step requires the addition of that lends an air of rich- resistance to the measured circuit, until the read- ness to receiver. your ing of the meter drops to one-quarter of its ori- Priced at $2.25 ginal value, it is well to vary the coupling to a point where this division will be simple. At an original reading of 60 or 80, it is quite easy to add resistance to the circuit until the reading falls to 15 or 20. Resistance is added to the Recording Dial circuit by means of the controls on the resis- tance box which, until this time, had been set this record- new style at zero. When the one quarter reading is ob- ONing dial, ample space tained, reference is made to the resistance box has been provided to jot and the resistance noted. This constitutes the down call letters, thus in- resistance of the coil and the meter at that par- suring a permanent record ticular frequency. Usually the resistance of the meter is known and its value be deducted of dial settings. The dial may from the reading obtained. itself is beautifully propor- This whole system is repeated for each fre- tioned, made of genuine quency point to be measured. Bakelite with handsome

embellishments on a mat- TUBES AND R.F. COILS: HOW THEY SHOULD BE ted background. Truly a MATCHED IN A RECEIVER product of master crafts- OBTAIN maximum in a men who specialize in the efficiency receiver using radio frequency amplifi- manufacture of dials. TOcation, it is necessary to have transformers Priced at $1.75 designed for the type of tube used in the set. This statement has been amply justified as the result of exhaustive tests made by indepen- MYDAR RADIO CO. dent engineers who were interested in the problem. 3 CAMPBELL ST. If a receiver is the r NEWARK, -N.J. using 0-299 uv-igg type of dry cell tubes, with proper transformers, and is changed over to the C-3OI-A or uv-2oi-A

Tested and approved by RADIO BROADCAST RADIO BROADCAST ADVERTISER 229 DISTANCE THE OBEDIENT SLAVE TO YOUR DESIRES

* APEX mastery over the most advanced radio engineering principles makes distance the obedi- ent slave of your desires and places at your in- stant command the whole continent of radio Upon request, we enjoyment. will gladly mail The infinite care and skill employed in perfect- descriptive folder ing the mechanical construction of APEX Radio Apparatus is radiantly reflected in the rich beauty of design, harmony of proportion and elegance of finish that stamp all APEX sets with an unmistakable mark of master craftsmanship. You are cordially invited to inspect this com- plete showing of Quality Radio Apparatus. Only a dependable merchant is given the APEX dealer franchise. Your APEX dealer will gladly make a personal demonstration of APEX Quality Radio Apparatus. APEX ELECTRIC MFG. CO. 1410 W. 59th St., Dept. 1204 CHICAGO, ILL. Also makers of the famous APEX Vernier Dials and APEX Rheostat Dials which are sold by every good dealer in Radio.

QualityRadioApparatus

Apex Entertainer Price 122.50 Apex Super Five Price $95 without accessorie

Apex Console Entertainer Price $27.50

Prices West of Rockies Slightly Higher Canadian Prices Approximately 40 % Higher

if Tested and approved by RADIO BROADCAST 280 RADIO BROADCAST ADVERTISER

type of tubes, it will be necessary to change the radio-frequency transformers also, if equally efficient results are to be obtained. to Land This is made necessary by the fact that the Helps characteristics of the tubes vary according to their internal construction. In the uv-igo. tube, the elements are very close together, mak- Everything ing it possible and advantageous to use more wire on the primary of the transformer. The You Catch tendency for a vacuum tube having a tuned in- put circuit to oscillate, is proportional to the inductive load or the number of turns on the The "Electrad" Lead-in meets that high of the transformer in the circuit. quality standard set by all "Electrad's" primary plate products. There is a difference. If the tubes were replaced with the C-3OI-A The convenientlead'in. Now you need or uv-2oi-A type, the circuit would become not scar or mar your walls or sash with unstable and oscillate readily, due to the dif- unsightly holes or ugly porcelain tubes. ference in construction of the elements of the This insulated and water- flat, highly latter type of tube. Fewer turns of wire should lead-in fits proofed be used on the of the transformers. under locked win- primary The curve of the transformer will fall off at one dows and doors. end of the scale and result in The windows may poor amplification of either the or low if the be closed tightly high waves, proper there need be no type of tube is not used. This is due to the loss of heat in the capacity of the input circuit of the tube, which room. Pliable, it varies in different tubes. As this is shunted bends into any across the secondary winding, it has sufficient shape meeting tuning effect on that winding to shift the area your every need. Price 40c. of maximum amplification from the desired band. Other Guaranteed Electrad When the tube characteristics are matched Radio Products up with the correct amount of wire on the primary of the transformer, then the circuit which construction, facilitate simplify will cover the whole wave band evenly, with installation and improve reception of radio sets Van- good amplification. In some types the core of ohms, Lamp Socket Antenna, Certified Grid Leaks, the transformer is filled with finely powdered Resistance Coupled Amplifier Kits and many others. iron or iron laminations. The use of iron in the At your dealer's, if he can't supply, write us. core broadens tuning so that the transformer ELECTRAD, Inc. may be used over the entire wave band, without the need of a variable condenser for tuning. 428 Broadway New York City

When Writing to the Grid

TYPEWRITTEN letter, written on one A side of the paper only, is to be preferred.as it aids in the quick formation of a satisfactory reply. Don't fail to send a stamped addressed envel- ope with your inquiry. ELECTRAD" LIGHT- Don't send a second inquiry about the first. NING ARRESTER Don't include questions on subscription orders Price 50c. Indoor type. or for other of "ELECTRAD" AUDIOHM Approved by Under' inquiries departments Doubleday, writers. Should A necessary tone and quality controlling fire Page & Company. device. Placed across of 6rst occur from lightning you secondary In us all the information audio transformer it eliminates distortion will have insurance diffi- asking questions give and transformer noises. Requires no * culties unless you have that will aid in advising you. If the question or tools to attach. Fits an approved arrester. drilling, soldering relates to described in RADIO BROAD- any transformer. $1.50 each. apparatus CAST, give the issue, page number, and figure number of the circuit diagram, etc. Be explicit yet brief.

ELECTRAD GRID BLANK INQUIRY

Editor, The Grid RADIO BROADCAST The "Electrad" Certified Fixed Garden City, J^ew Condenser is a revelation in accuracy and design. Ingenious, rigid binding DEAR SIR, and firm riveting fastens parts securely Please give me the fullest information at Six different points insuring positive on the attached questions. I enclose a electrical contact. Impervious to temp' stamped envelope. erature and climatic variations. Exerts I am a subscriber to RADIO BROADCAST even pressure upon the largest possible EH and therefore will receive this information surface can't work loose. Binding strap free of charge. and soldering lug in one piece. Ac- curacy and quietness assured always. EH I am not a subscriber and enclose $1 Value guaranteed to remain within 10% to cover cost of answers. of calibration. Standard capacities, 3 types. Licensed under Pat. No. 1,181,623 NAME . . . May 2, 1916 and applications pending. The Six Point Price 30c to in sealed dust 75c and mois- ADDRESS . ture Pressure Condenser proof packages. G. D.

Tested and aooroved by RADIO BROADCAST RADIO BROADCAST ADVERTISER 231

What to give the radio fan Give him a two- ampere Tungar if he has a storage bat- tery of any kind. It will charge all his radio batteries and his auto battery, too.

Or, for bigger jobs, give him a five-ampere Tungar built to do the same work but to do it more than twice as fast.

Every man who has a storage battery wants a charger. And every man who wants a charger wants the original General Electric bulb charger the Tungar.

The Tungar is a G-E prod- uct, developed in the Re- search Laboratories of Gen- eral Electric. TunarREG. U.S. OFR The new Tungar charges 5J^^^ any make and size of storage battery: radio "A" and auto IB ATT E RY _CHARG E.R batteries, and "B" batteries as high as 96 volts in series. Tungai a registered trademark is found on]}! Prices on the genuine. Look for it on the name plate. Two ampere size . $18.00 Five ampere size . $28.00 Merchandise Division

60 cycles . . 110 volts General Electric Company, Bridgeport, Connecticut GENERAL ELE

Jr Tested and approved bv RADIO BROADCAST RADIO BROADCAST ADVERTISER A KEY TO RECENT RADIO ARTICLES By E. G. SHAULKHAUSER

is the second instalment of references to THISarticles which have appeared recently in var- ious radio periodicals. Each separate reference should be cut out and pasted on cards for filing, or they may be pasted in a scrap book either alphabetically or numerically. A brief outline of the Dewey Decimal System (employed here) appeared in the November RADIO BROADCAST. B-T "COUNTERPHASE-SIX" (Built from Kit)

R 1 1 3. TRANSMISSION PHENOMENA. TRANSMISSION Radio, PHENOMENA. "Popular Sept. 1925, pp. 199-206. How the Air Affects Radio," E. E. Free. In a simple non-technical way the author tells us how the two theories of wave propagation, the Heaviside Layer Instructions and the affect radio trans- System of theory Gliding Wave theory, may mission. Probably both theories are correct. Apparently the ions and free electrons in the air account for fading, bending, and absorption. Sir Joseph Larmor, on October the 27, 1924, stated that he believes most of the phenomena Simplify Building pertaining to wave reflection occurs about fifty miles above the earth's surface. How free electrons may affect radio r energy distribution is explained in greater detail. Ri 13. TRANSMISSION PHENOMENA. ABSORPTION. Popular Radio. Sept. 1925, pp. 207-21 1. "How Radio Dead-Spots are Found by a Wandering COUNTERPHASE Perrine. Broadcasting Station," J. p. The distribution of radio wave energy about a broad- casting station located in a city, has been determined with the aid of a mobile receiving set. Energy received is com- pared with that given out by a local oscillator, and field B-T is a combination of the best "Counterphase" strength is recorded in microvolts per meter. The area apparatus ever put in a receiver and the exclusive patented about the Washington, District of Columbia station, WCAP, THE within a radius of 50 miles, is shown in diagram with contour B-T method of oscillation control which gives maximum lines. These tests have given very valuable and inter- esting results, showing effect of ground condition, build on all wave efficiency lengths. ings, hills, and various conducting materials found in theth< You can build the "Counterphase" with one, two or three earth, on the direction and intensity of the wave. Ro8o. MISCELLANIES. TABLES stages of R. F. or buy a complete factory built 6-tube receiver. COLLECTIONS, TABLES, Popular Radio, Sept. 1925, pp. 221-226. as as sensible Two tuning controls give the most simple well "Useful Charts for Amateurs," Lieut. C. C. Todd. jr. Simple and valuable information to guide the constructor tuning. in designing coils and determining proper size condensers "Counterphase" kits for the home builder include a complete to cover certain wavebands, is contained in this article. Eight charts show the relation between capacity, induc- set of instructions with progressive circuit charts in nine colors tance, wavelength, and col! turns, to cover both short and The information is well same colors as wires There's no excuse for long wavelengths. very presented (the furnished.) and the diagrams are clear. error. RSoo (530) PHYSICS ATOMS Ask your dealer, he'll tell you about B-T performance. Popular Radio, Sept. 1925, pp. 232-236. "The Atom," Sir William Bragg. Article No. 2 deals with the nature of gases. The ar- rangement of the electrons in various atoms, their number, and how the various combinations account for the different Best Ever Tested" elements, is described. Models illustrate the facts out- "The We lined in a The author relates the very simple way. theory of the electrons and atoms and the part they play in our present day research, in simple language. says a leading laboratory of the B-T "Euphonic" Audio Transformers. R36o. RECEIVING SETS FREED- Popular Radio. Sept. 1925, pp. 244-254. EISEMANN. Listen to a set equipped with "Euphonies" and you'll appreciate "How to Get the Most out of Your Ready-Made Re- the on both and low notes. ceiver," S. G. Taylor. improvement high The new Freed-Eisemann five tube receiver, NR2O, is The B-T "Euphonic" is the discussed, illustrated, and described in great detail, A de- scription of the theory, operation, and equipment, with only transformer designed plenty of photographs and diagrams, give the set owner all the desired information. The B life for this to in such battery set, permit mounting using various sizes of B batteries, is shown in a table, manner that terminals may R 304.1 WAVEMETERS. WAVEMETERS. always be brought where Popular Radio, Sept. 1925 pp. 267-271. Oscillating, "An Oscillating Wavemeter/ S. G. Taylor. they are needed to prevent A description of an oscillating wavemeter, using a vacuum tube in a is Parts crossed a simple oscillating circuit, given. required, wiring, frequent and size of coils to use in order to cover frequencies from cause of and dis- 9091 kc. (33 meters) to 498 kc. (602 meters), are listed. The howling instrument is valuable in measuring capacities and induc- tortion. tances. The circuit diagram shown is the modified Hartley. the tone Compare and you'll R343. ELECTRON TUBE RECEIVING SETS. RECEIVER, use Radio Engineering. Sept. 1925, pp. 433-441. RX-l. only "Euphonies." "How to Build the RX-i." This receiver is one especially developed in the Darien Because It's Different Laboratory. It is a non-regenerative four-tube set known as the RX-I receiver. The receiver was designed to give You Should Read easy control, good quality, and precise tuning, together with plenty of volume. Diagrams and data are ample to permit the constructor to build this receiver. The best parts Better Tuning available are listed, the cost of these being only about $32. PROCESSES. MOULDING before a set or R72O. you buy RADIO: 2.2 to 1 Radio Engineering. Sept. 1925, pp. 455-458. BAKELITE. Not Do Your Own parts. 80 pages of facts, 4.7 to 1 "Why Moulding." The article describes the equipment necessary for mould ing hook-ups, tuning hints, dis- bakelite parts on a rather small scale. The process is not difficult and the equipment can be installed in small estab- cussions of latest radio topics. Postpaid, 10 cents. lishments without excessive cost. The method used in molded is described in detail. Literature B-T free on request. making parts Photographs describing products of the machinery are shown. R384.I. WAVEMETERS. LECHER WIRES. QST. Sept. 1925, pp. 11-12. "Practical Lecher Wires," E. C. Woodruff. BREMER-TULLY MFG. CO. Description and arrangement of Lecher wires with con- stants of construction are given in detail, showing diagram. In making measurements of waves the wires are connected S Canal Street 111. 532 Chicago, to a vacuum tube circuit as shown in Fig. i, and a milli- ammeter in the plate circuit indicates resonance. A calibra- tion chart and graph show the method of using these parallel wires.

Tested and approved by RADIO BROADCAST RADIO BROADCAST ADVERTISER 233

Imagine a Radio Set stripped of these parts

What a useless collection of reflects the experience and the wood, wire and metal it would opinions of radio manufacturers, be. Realizing that the parts and great and small. accessories shown here are wholly Radio set and parts manufac- or partly of Bakelite, gives you turers have every facility for a vivid picture of its importance all insulation materials to Radio. testing and over 95% have standardized To-day Bakelite is used in a on Bakelite. This indicates how greater variety of radio parts really important it is for you to than ever before and the num- make sure that the set or parts ber grows constantly. This that you buy are Bakelite in- dominance of Bakelite in radio sulated.

Write for Booklet 29

BAKELITE CORPORATION 247 Park Avenue, New York, N. Y. Chicago Office: 636 West 22d Street

Bakelite is anexclusive trade mark and can be used only on products made from materials BAKELITE manufactured by the is the registered trade Bakelite Corporation. mark for the phenol It is the only material resin product manu- which may bear this factured under pat- famous mark of excel- ents owned by the lence. Bakelite Corporation. BAKELITEREG. U.S. "AT. OFF:. THE MATERIAL OF A THOUSAND USES jf Tested and approved by RADIO BROADCAST -^ 234 RADIO BROADCAST ADVERTISER

Ro84. TABLES. CHARTS. QST" . Sept. 1925, pp. 16-17. Ind. Sr w. I. Designing the Secondary Coil," G. H. Burchill. Using double cotton covered wire, the inductance and wavelength of cylindrical coils, closely wound, can readily be determined with the aid of the chart in the form of a graph. A simple description of coil design and method of procedure is given.

R8oo (535.3). PHOTOELECTRIC SELENIUM CELLS. PHENOMENA Kadio Engineering. Sept. 1925, pp. 442-443. "Selenium and Photoelectric Cells, S. Wein. The third chapter on selenium cells gives the construc- tion of different types of cells by various scientists: Tainter, Bell, Mercadier, Townsend, and Cherry. Keferences are listed.

R356. TRANSFORMERS. TRANSFORMERS. QST. Sept. 1925, pp. 21-24. "Transformers and Reactors in Radio Sets," R. H. Chad- wick. In the first article on transformers and reactors, the author takes up the general theory, regulation, and efficiency, and describes the construction and operating principles of various types of commercial transformers. The leakage reactance is a governing factor in proper transformer de- sign. Useful information for users of these instruments. R342.I5. AMPLIFIER TRANSFORMER. AMPLIFYING QST. Sept. 1 92 5, pp. 27-29. TRANSFORMERS. High Ratio and High Amplification," R. S. Kruse. Some misunderstood principles about audio and radio- frequency transformers are cleared up by the author. Stage to stage amplification depends on the regeneration as well as the transformation ratio and the tube constants. When the transformer is largest, both regeneration and amplification are strongest. A 2:1 transformer may give much better amplification than a 6:l, depending upon design. Diagrams illustrate the points under consideration. R402. SHORT WAVE TRANSMITTERS. SHORT WAVE QST. Sept. 1925, pp. 30-32. TRANSMITTER " A Power-Amplifier Transmitter for the Low Waves W. H. Huffman. The circuit arrangement in a Colpitts oscillator, using an added power amplifier, is described. The transmitter operates well on very short wavelengths. It transmits a very steady frequency and with the apparatus recom- mended, has a tuning range from 14990-3894 kc. (20-77 meters). Since the set uses uv-2O2 tubes it can be operated on storage or dry batteries, and used as an emergency layout. Operating adjustments and list of parts required, including circuit diagram, give complete construction data. Rii3.4. IONIZATION; HEAVISIDE LAYER. HEAVISIDE QST. Sept. 1925, pp. 33-34. LAYER THEORY. Is There a Heaviside Layer?" G. W. Pickard. A brief discussion concerning some of the transmission phenomena, with particular reference to various theories on reflection and refraction, is contained in a letter to QST by the writer.

RSI 2. RADIO BEACONS. LIGHTHOUSE, RADIO BROADCAST. Oct. 1925, pp. 710-724. Radio. "And Now The Radio Lighthouse," J. C. Young. Radio service to ships at sea has become absolutely necessary. Radio signals help guide ships when near the coast and give bearings when needed. What advances have been made in guarding against danger, what pleasure and enjoyment has been derived through the use of radio to those sailing the waters, is well pictured in this article.

Ri40. RADIO CIRCUITS. ROBERTS RADIO BROADCAST. Oct. 1925, pp. 725-731. CIRCUIT. "New Developments and Experiments with Receiving Circuits," K. Henney. The Roberts Knockout receiver offers possibilities for A BRISTOL Loud Speaker will Christ- development along many lines. In this article some of the bring everlasting experiments carried on at the RADIO BROADCAST Laboratory ** mas joy to the whole with this circuit, are discussed. How a fifth tube may be family. added, how the reflex stage may be eliminated, how the It has all the volume will ever but its fine circuit is neutralized, how regeneration may be employed you wish, in either detector or amplifier, are changes that may be tried with point, its outstanding claim for distinction, is its tone, success. a true, clear, natural reception of voice or instrumental Rooy. 2. U. S. RADIO INSPECTION SERVICE. RADIO RADIO BROADCAST. Oct. 1925, pp. 743-744. CONDITIONS. music. This is because it is a true musical instrument "Guiding the Good Ship Radio," D. K. Tripp. An interview with W.ID. Terrell, Chief Supervisor of Radio, not a unit in a horn. concerning radio conditions in the U. S. at present, reveals merely phone his views about the department's attitude toward the Bristol Loud have electro- amateur, the broadcaster, and the service both can render Speakers highly developed toward bettering conditions in radio. tone and non-metallic horns with magnetic mechanisms, Rija. AMPLIFYING ACTION. AMPLIFYING long, freely sound chambers. RADIOBROADCAST. Oct. 1925, pp. 745-750. PRINCIPLES. vibrating "Some Remarks on Audio Amplification," G. C. Crom The super S and super C models are with the Jr. equipped Good radio reception depends upon proper amplifier Super-Unit which contains a design. The functions of each part in the amplifier circuit specially designed diaphragm are discussed in detail. Good parts must be used for best of broad pitch It not the low reproduction. Distortion may be produced by any one range. reproduces only of four things as stated. High plate voltages are recom- mended and are of ad when C pitched notes but the high as well. vantage proper battery voltages and by-pass condensers are inserted, as shown in Fig. 2. There are four Bristol horn or cabinet Speakers, type, R373. 2. MICROPHONES. MICROPHONE RADIOBROADCAST. Oct. priced at $15.00 to $30.00. If not at send " 1925, pp. 769-770. PLACING. your dealer's, More About How to Place the Microphone." for our new booklet. "How to select loud Methods of placing microphones for picking up band and your speaker." orchestra music in and put of the station studio, are shown. In particular, the placing of several microphones at the Lewisohn Stadium in THE BRISTOL Rad Div - New York City and on the campus COMPANY, AH WATERBURY, CONN. of New York University, in order to broadcast music from, large organizations, is of interest. For 36 Years Makers of highly accurate and sensitive Bristol Recording Instruments. R375.3 ELECTROLYTIC RECTIFIERS. RECTIFIERS. RADIOBROADCAST. Oct. 1925, pp. 774-780. Chemical. "Notes On Chemical Plate Supply Units," J. Millen. AUPI pNE The chemical rectifier here described, employs two or ^ more jars in order to handle output voltages up to 1 50 volts BRISTOL Loud and enough current for the receiver, at the same time giving Speaker absolutely no line hum in the output circuit. The dis- cussion covers all phases of construction and operation in a very thorough manner. List of parts and diagrams of circuits and complete unit are added.

Tested and approved by RADIO BROADCAST RADIO BROADCAST ADVERTISER 235

FILTER CONDENSERS

ADIO BROADCAST'S article in this issue on Improved Plate Current Supply Unit" shows that the following TOBE condensers can be used in building the set: 5 type 708 and 7 type 709. .1 M.F.D. Type 705 Any 'B' battery eliminator circuit depends very large- Price $ .70 ly for its operating efficiency upon the filter condensers used. all of 1. M.F.D. TOBE condensers alone possess the follow- Type 708 ing favorable characteristics: Price 1.25 Will operate at voltages up to 700 D. C. without break- 2. M.F.D. down or overheating. Type 709 High megohm resistance indicating perfect insulation. Price 1.75 Capacities guaranteed to be within 5% of accuracy. Extreme heat or cold has no effect on TOBE condensers. 4. M.F.D. Compact and handsome in appearance. Type 711 Price 3.75 Tobe condensers are better condensers distinguisha- ble by their silvered finished case. Ask your dealer for them by name "TOBE."

CORNHILL BOSTON, MASS.

Tested and approved by RADIO BROADCAST 236 RADIO BROADCAST ADVERTISER

R550. BROADCASTING. SUPER-POWER RADIOBROADCAST. Oct. 1925, pp. 761-768. STATIONS. "A Debate: Resolved, That 5OO-watt Stations Are Not Sufficient for Program Service," Affirmative: Mr. Dreher. Negative: Prof. Williams. The pros and cons of so-called super-power stations, is given in two articles. Much information is contained in both, especially in regard to power and noise level.

Rii3.i. FADING. FADING Radio News. Sept. 1925, pp. 278ff. SIGNAALS. "Concerning the Nature of Fading," J. H. Dellinger. The problem of fading has become more serious than the problem of static, primarily because so much fading can occurs on the JN high frequencies (1500 kc. and where you up) much research is done at The O being present. Bureau of W Standards has undertaken a series of tests to determine the cause of fading. It is probably due to the shifting of the upper atmospheric conducting surface. Rs82. TRANSMISSION OF PHOTOGRAPHS. PHOTOGRAPH Radio News. Sept. 1925, pp. 278ff. TRANSMISSION. buy Matched Tubes "See With Your Radio," W. B. Arvin. The Jenkins-Moore system of television is described. A photoelectric cell converts the black and white of a pic- ture into electric currents while a lighting device, the Moore and be certain will be lamp, picks up these currents and changes them back to your reception light and shadow on the screen. The breaking up of the for picture transmission is done with the prismatic disc, clear, smooth, loud and uniform a very simple method. Synchronism is accomplished with synchronous motors at both ends. This system is said to be the best one developed to-day, and was demonstrated at Washington last June.

R323. GROUND AND UNDERGROUND UNDERGROUND ANTENNAE ANTENNAE Radio News. Sept. 1925, pp. 3oiff. "Underground Radio." W. H. M. Watson. Experiments with underground antennas with frequencies of from 5996 kc. (50 meters) to 1666 kc. (180 meters) are described in detail, with varying results. Good transmission distance is possible with low power input after proper ad- justments are made and antenna placed properly. The antenna is very directional. An article on underground and under-water antennas, is reprinted from Dec. 1919, Radio News showing what was accomplished along this line several years ago.

R38i. CONDENSERS. CONDENSERS, Radio News. " Sept. 1925, pp. 3o8ff. S. L. F. More About Straight Line Frequency Condensers," S. Matched Harris. A general discussion concerning condensers, in particular the straight line frequency condensers, is presented to clear up certain points. The question of low minimum capacity for definite sized condensers, of condenser resistance when plates are nearly all the way out, and of tuning with Blue Tubes straight line frequency condensers, is considered. Ri4o. RADIO CIRCUITS. REGENERATIVE (Peanut or Standard Types) Radio News. Sept. 1925, pp. jioff. CIRCUITS. "Single-Tube Circuits," L. W. Hatry. mark a in The author new step Radio. They are what reviews regenerative circuits, inductive and Blue Specials capacitive, using one tube. All other circuits are merely radio has been for combinations of these simple circuits. A understand- every "bug" looking " " good" ing of these, makes the "dynes and plexes comparatively cost a trifle more and and wondering when and where they simple. The Reinartz, the ultra-audion, the Cockaday, and receive considerable attention in this are worth it. others, discussion. Try them, could get them. and you'll never again R43O. INTERFERENCE ELIMINATION. INTERFERENCE It is most to radio that Radio News. 2ooff. REDUCTION. bother to to match important gooa reception Sept. 1925, pp. try tubes "Directional Reception Reduces Interference," P. C. your are matched and pull in harmony. HoArnt1 ' tubes yourself; 501 -A A Equal pull in the tubes means smoothness of re- is for storage batteries, ception sweetness of sound full throated vol' and is packed singly ume resonant and in kits of three clarity. the two loops, the latter are mounted on a long turntable at some distance apart (depending on wavelength). Fig. 3 and five matched tubes. shows the general form of the directional BLUE SPECIALS are matcned tubes. care- characteristics, After and Fig. I the circuit used. Several photographs give an 499 is for dry cells,with ful selection actual test the individual charac- idea of the general layout. The tuning is simple and the by results obtained peanut base and is were very good. Amateurs and experi- teristics are plainly indicated and they are packed menters can amplify along these lines. and in packed singly kits of three five in and matched tubes ready for R375. DETECTORS AND RECTIFIERS. RECTIFIER kits of four and six Radio News. immediate use. Made for batteries Sept. 1925, pp. 293ff. TUBE. storage only. "A Neon-Filled Rectifier matched tubes. New Tube," J. Riley. This of selection enables us also to discard The tube used as rectifier for B battery eliminators has process two electrodes Price each of aluminum, a rod and a cylinder, and con- $2.75 all inferior tubes and retain only the first grade. tains neon gas at a pressure of six millimeters of mercury. Its action in d. c. and a. c. circuits is discussed in detail them the box Buy by and illustrated by diagrams. Other possibilities of the for best reception. BLUE SPECIALS give wonderful results. neon lamp are enumerated and offer a field of research. Try them. Find out for yourself what a big R35I. SIMPLE OSCILIATORS. OSCILLATOR. Radio it is to have matched tubes. Re- Journal. Sept. 1925, pp. 12-15. advantage "A Laboratory Oscillator," H. W. Leighton. The describes member they are unconditionally guaranteed. author the construction of a laboratory oscillator and gives some of its uses. The circuit is shown See the line Booth No. in Fig. i. Calibration of the oscillator is simple when a Sylfan 34 standard wavemeter is available. Measurements of trans- formers and filter in Chicago Radio Exposition for use super-heterodynes are made according to Fig. 2, and curves plotted showing how one can Manufactured and Marketed Exclusively Thru Jobbers by determine just how to select the proper apparatus to match. Small fixed, condensers can also be measured with BAKER- SMITH Inc. this oscillator. CO., R343. ELECTRON TUBE RECEIVING SETS. RECEIVER, New Call Building, San Francisco Radio Journal. Sept. 1925, pp. 14. Brownjng- Drakf. "New Bill Branch Office Addresses Type Browning-Drake," Massaggee. The constructional details of the Browning-Drake re- Portland, Ore., Henry Bldg. New York City, 1270 Broadway ceiver are described, particular attention being called to several minor details which nevertheless are essential if the Salt Lake City, Atlas Bldg. Chicago, 30 N. Dearborn St. set is to operate well. A proper design of the coils used is Seattle, L. C. Smith Bldg. Denver, McCHntock Bldg. essential. Extreme selectivity and sensitivity is claimed Los Angeles, 443 South San Pedro Street for the 4-tube set in comparison to other sets of similar size. (Further details in Oct. Vancouver, B.C., 179 Fender Street, West issue) 500 R3&0. RECEIVING SETS. GREBE CR. 17 Radio Journal. Sept. 1925, pp. 15. "The New Grebe CR-i7," M. Best. Photographs and wiring diagram of the Grebe short wave receiver, including a short description of the operating principles, is given.

Tested and approved by RADIO BROADCAST RADIO BROADCAST ADVERTISER 237

\^*^^> s ttetiimwuftr^*

%-

oJOl iUU |J rr o*HOMETR, . T KARAS CCOHDENSER /tangement Line Condenser Ordinary Condenser Arrangement of Wavelengths Straight Wavelength Arrangement Of Wavelengths on Dial Ordinary straight capacity con- With straight-line-wavelength con- The New, Scientific Karas Orthometric densers crowd 70 of the 100 wave- densers 57 of the 100 wavelengths Condensers insure absolutely equal sep- lengths into the first 30 points are crowded into the first 30 points aration on the dial of all wavelengths of the dial. of the dial. throughout the entire broadcasting range. Tuning Marvelously Simplified with Karas Orthometric Condensers

The condenser that brings in KDKA where it be- longs at 53 on the dial. Remember, 52 of the 100 '* allotted wavelengths must come in below KDKA. pate Mtt

10 20 30 40 50 60 70 60 90 100

Spreads Stations Evenly Over the Dial No Crowding Whatever

I HE Karas Orthometric Condenser positively separates all adjoining wave- lengths by EQUAL distances on the dial, giving you the full benefit of the T10 Kilocycle frequency separation fixed by the Government. Ordinary condensers jam 70 of the 100 Government day broadcast receiving sets the Last Word in making allotted wavelengths into the first 30 points of the dial REAL SELECTIVITY POSSIBLE. even straight -line -wavelength condensers crowd 57 of them below 30. The Karas Orthometric is a "job" that will delight the eye of the mechanical critic. It is made entirely of brass all die With Karas Orthometrics, each point on the dial cor- frame and plates stamped plates, responds exactly to one of the 100 allotted wave- patent leveled and solidly bridged to insure permanent lengths. The result is marvelous simplicity in tuning rigidity and alignment. Every joint throughout is sol- with better, clearer reception you get all the side bands dered. Grounded frame and rotor, stator plates without interference. supported on hard rubber insulation. Tapered adjust- able cone bearings, spring copper pigtail connection, The Karas Orthometric stands absolutely alone! an automatic stops in short, a condenser that is both eccentric condenser, scientifically designed for present theoretically and mechanically perfect.

If Your Dealer is NotYet Supplied, Order on this Coupon We are supplying Jobbers and Dealers as fast as the output of our If factory permits. your dealer is not yet supplied, order Send No With this direct on the coupon. You need send no money with your Money Coupon order. Condensers will be delivered C. O. and receive D., you Karas Electric Co., 4042 N. Rockwell St., Chicago them to our unconditional of satisfaction. subject guarantee Please send me Karas Orthometric Condensers, run the risk of delay? Order NOW! Why size at $ each. I will pay the postman the list price, plus postage, on delivery. It is understood Back Guarantee that I have the privilege of returning these condensers any time Money within 30 days if they do not prove entirely satisfactory, and you will Karas Orthometric Condensers are uncon- SIZES AND PRICES refund my money at once. ditionally guaranteed to give you absolute 23 plate, .0005 Mfd.,$7.00 satisfaction. They may be returned for full 17 plate, .00037 Mfd., 6.75 Name- refund any time within 30 days. 11 plate, .00025 Mfd., 6.50 Address- Karas Electric Co., 4042 Rockwell St., Chicago For OverSO Years Makers ofPRECISION Electrical Apparatus Dealer's Name If you send cash with order, we'll send condensers postpaid. Tested and approved by RADIO BROADCAST 238 RADIO BROADCAST ADVERTISER

Is Your Set A

How to Prevent Your Receiver Causing Interference and Thus Spoiling Your Neighbor's Re- ception

are still many single-circuit bloopers ORIGINAL in the trend in as use, although general design, far as commercially made receivers are concerned, seems to be toward receivers which are almost

incapable of causing interference, however carelessly handled. The excellent instructions appearing be- low have been specially prepared by the Radio Branch of the Department of Marine and Fisheries of the Dominion of Canada, for circulari^ation among all Canadian broadcast listeners. On the back of all Canadian receiving licenses is the follow- " ing note. When using a receiver of the regenera- tive type for the reception of radio telephone programs, please avoid increasing regeneration to the point at which the receiver begins to oscillate, otherwise you will cause interference with neighbor- Are sist ing receiving equipments. you doing your R ance-CoupIed best to observe this?" The point is that many ~"**~ owners of receiving sets capable of radiating squeals, $3 22 Amplifiers cause such interference purely from inadequate knowledge of the handling of their sets, and it was for their benefit that this circular was printed. These instructions should help many readers of RADIO BROADCAST who are looking for clear directions on how properly to use their regenerative sets. THE EDITOR.

HOW MUCH INTERFERENCE A RECEIVER CAN CAUSE

RECENT survey of radio broadcast reception conditions in the more popu- A lated centers of the Dominion of Canada indicates that approximately fifty per cent, of GUARANTEED I RADIO TUBES the "preventable interference" which prevails. is caused through the incorrect operation ot To increase the effi- The Cleartron Hi- regenerative receiving sets by the broadcast listeners themselves. ciency of a receiver Constron is a Hi- The survey further indicates that most of the employing Resist- Mu Tube with an interference is due to a lack of knowledge of ance-Coupled Amplification, and amplification constant of 20, correct methods of adjusting a regenerative to the full measure of tone for Resistance- get especially designed receiving set, and it is accordingly hoped that a and faithfulness of and purity repro- Coupled Reactance-Coupled material reduction in the same way may be duction, for which this method of Amplifiers. It is the result of effected if the broadcast listeners can be per- amplification is noted, use Clear- years of research work and is suaded to cooperate in an endeavor to clear the air of with this end tron Hi-Constron Tubes Type the original and genuine Hi-Mu regenerative whistles, and, 101A. Tube. in view, the following instructions for operating this class of receiving set have been drafted.

The Following Types $2.50 WHAT IS REGENERATION? I RON -CLAD C-T 201 A CTX 120 '"THE principle of regeneration, as used in GUARANTEE * C-T 199 Standard C-T 400 Rectron Tube radio receiving sets, is that a part of the All Cleartron Tubel ut guaranteed to Base for "B" Elimi- of the detector vacuum tube feeds back deliver positively perfect Battery output service and we authorize our C-T 199 Small Base nators into its own and thus increases the distributors to' mike replacement input greatly o* Clcamoa *ny Tube which proves volume of the unsatisfactory to the user ~ " signal. The 112 only requirement ts thai the CTX Power Tube $6.50 The electric waves the tube must not have been bunted out reaching receiving set from the station travel down Clevtron Vacuum Tube Co All transmitting 28 Wt.t Types Equipped With Genuine Bakelite Bases 44th Si the antenna wire through the primary coil in the At All Reliable Dealers if set and so to earth down the ground wire. The weak electric current resulting from this influ- Write for FREE six-page folder giving valuable ences the vacuum tube in such a way as to set it information regarding radio tubes functioning. Cleartron The resulting output from the plate circuit of Vacuum Tube Company this tube is fed back in such a manner as to set Executive Offices up a "field," or "influence," in the part of the 28 West 44th Street West New York, N. J., U. S. A. circuit connected to the input (the grid) of the New York City Birmingham, England tube. This "field" induces in the input circuit a current of electricity of the same frequency as that of the received electric waves. The energy, therefore, which comes down the antenna wire FOR BETTER RECEPTION is automatically strengthened by an impulse from the output of the detector tube.

Tested and approved by RADIO BROADCAST RADIO BROADCAST ADVERTISER 239

NATIONAL Velvet Vernier DIAL Type B, Variable (Patents Pending)

Positive Control Variable Ratio

Easily Mounted Velvety Smooth Gearless Graceful Design *

With This NEW National Type B, Velvet Vernier Dial, YOU Control the Reduction Ratio!

a difference in the tuning of your Easily mounted on the \" shaft of any stand- WHATset when you replace your plain dial ard type of variable condenser. The only with a new NATIONAL Type B Variable tool you need is a screw driver. (patents pending). You'll be astonished. from a minimum of Any ratio you desire, The same velvety smoothness, the same free- 6 to 1 to a maximum of 20 to 1 is instantly dom from backlash, the same mechanical drive obtained by shifting a small lever. Note how as the famous A Velvet Vernier Dial, it separates the stations operating on the Type lower wave lengths. (patents pending). Price $2.50. The NATIONAL KIT for the popular circuits and hook- ups gives amazing results to am- ateur set -builders. Comprises the NATIONAL CONDENSER and the wonderful BROWNING-DRAKE TRANS- FORMER. Complete in one package, Price $2 2. Makes a most welcome Christmas Gift.

Write for Bulletin 106 R. B.

NATIONAL CO., INC. W. A. READY, President NATIONAL Tuning Unit NATIONAL Tuning Unit Type B D-2 110 Brookline St. CAMBRIDGE, MASS. Type B D-l

Tested and approved by RADIO BROADCAST 240 RADIO BROADCAST ADVERTISER

WHAT IS OSCILLATION?

I controlled, this action will continue ''JNLESS until the saturation point or climax is reached, the tube then being said to be in a state of oscillation. When a receiving set is in oscilla- ACMEWIRE RADIO PRODUCTS tion, it causes howling and squealing in your own and your neighbor's receiving sets. Regenera- tion should therefore never be allowed to proceed to this point as it then constitutes a public nuisance. On commercial receivers, regenera- tion is not always described by this name, and Stranded Enameled Antenna the dial which controls this feature of the equip- ment may be designated by any of the following The best outdoor antenna you can put up. 7 strands terms: Regeneration; Reaction; Tickler; Feed- of surface for enameled copper wire; maximum recep- back: Amplification; Varind; Sensitivity, etc. tion. corrosion and Enameling prevents consequent When a radio receiving set in a state of oscilla- weak signals. 100, 150 or 200 ft. coils, boxed. tion is being tuned to a broadcast station:

(1) It causes whistles in radio receiving sets, Antenna Wire of all to the same station. Loop types, which are tuned This interference be heard up to a distance You can make a with Acme wire made of strands of fine may good loop 65 copper of several miles. wire, green silk covered. Flexible; non-stretching, neat. (2) It distorts the quality of your own music.

(:)) It uses more B battery power and The Celatsite Wire therefore the life of the B battery is reduced. Original (4) It tends to reduce the life of the detector Celatsite is a tinned copper bus bar wire with a non-inflam- tube. mable "spaghetti" insulation in five colors. Supplied in 30 inch lengths. When a radio receiving set, in a state of oscilla- tion, is exactly tuned to a broadcast station, it is said to be in the state of zero beat. This Flexible distorts the broadcast and also in- Varnished "Spaghetti" reception terferes with neighboring receiving sets which A perfect insulation tube for all danger points in set wiring. are tuned to the same station. Costs little more and is worth a lot more than the cheaper sub- In a word, carried to oscillation stitutes offered. Black, yellow, red, green, brown; for wires No. regeneration causes to 10 to No. 18. 30 inch lengths. great annoyance your neighbors, poor reception and expense to yourself, and has no advantages whatever. Flexible Celatsite

Flexible stranded wire for "point to point" and DOES YOUR RADIO RECEIVING SET CAUSE sub-panel wiring latest method of wiring sets. INTERFERENCE? 5 colors, black, yellow, green, red and brown, one for each circuit. 25 foot coils. 'T'HE interfering whittle which you hear in * your receiving set may originate in your own set or it may be interference caused by your Celatsite Cable neighbor. In order to determine this point Battery you may make the following test: the control in a fixed For connecting A and B Batteries (or current supply) to Leave regeneration radio set. Silk braid covering 5 flexible Celat- position, slowly rotate the tuning dial, and site wires 5 feet long a different color for note particularly the change in sound of the each terminal. Prevents wiring and whistle. If the whistle rises and lowers in mess^v pitch "blown" tubes. Adds the greatly tp appear- sympathetically with the movement of your ance of your set. A* v ^ tuning dial it indicates that your receiving set is in a state of oscillation and probably causing jp .$*oend for Folder interference to other sets. On the other hand, V if the whistle does not change in pitch cor- responding to each movement of your tuning WIRE CO., Dept. B dial, but simply varies in volume, the whistle New Haven, Conn. is not caused by your receiving set, but is inter- ference produced by some other oscillating re- ceiving set in the neighborhood. Many so-called non-radiating receivers will, under certain conditions, radiate and thus cause interference. Make it your business to see that l 22 /2 Volt your set is not causing trouble. FROST RADIO un-acid If you are in doubt as to whether your set can TUBE * everlasting cause interference you can check the same by rechargeable making the following test, but be careful to do "B" CONTROL so at a time when only a few people are listening Storage Battery in, so as not to cause annoyance: Call a on the and ask him UNIT $ neighbor telephone 2.95 to listen in on a particular station at a pre- time and then tune own set to the *]21 includes arranged your chemical same station. Turn up your detector tube fila- (6, 25 or 35 ohms) ment to normal and put the regeneration control 45 volts $5.25. 90 volts*10.00. to its move dial five times and Poten- 112% maximum ; your tuning Vernier Rheostat volts J12.50, 135 across the to the COMBINEStiometer. Single hole mounting. 6, 25 volts tit. 75, 157!4 slowly point corresponding v o i t B tie. so. Gen- of that then or 35 ohm rheostat, 400 Potentiometer. Truly the biggest buy today. Easily charged on any current includ- tuning station, telephone your ing 32 volt Any detector had. Tested uine Moulded Bakelite. systems. special plate voltage and ask him if he heard the interference and approved by leadim: authorities such as Popular Radio labora- neighbor List; $1.75. Pacific Coast tories. Over 3 years sold on a non-red tape 30 day trial offer with corresponding to these five movements of the complete refund if not thoroughly satisfied. Further guaranteed 3 price slightly higher, yfars. Knock-down kits at greater savings. Complete "Haw ley" dial on your receiving set. If he heard your "B" 3attery Charger $2. 75. Sample cell 35c. Order direct send no write for the is that hundreds inc. money simply pay the expressman cost on delivers-. Or interference, probability HERBERT H. EROST, my free literature, testimonials and guarantee. Same day shipments. of others have also been annoyed at times by 314-324 WEST SUPERIOR STREET, CHICAGO B. 312 Conn. radiation from set. You should New York City Cleveland Kansas City Los Angeles Hawley Smith, Washington Ave., Danbury , your receiving RADIO BROADCAST ADVERTISER 241

Employs no fluids of any kind. Uses only one rectifying lube. Separate adjustment for detector and amplifier tubes. Handsomely finished in rich velvet-green Duco with solid walnut, satin finish top and bottom. Ample continuous "B" current for one to ten-tube sets.

Remarkable Tone Quality *-* ^ Amazing Volume and Selectivity^ without "B" Batteries in of "B" is to the overall of set. , place Batteries, guaranteed improve efficiency your It provides constant "B" current at proper potential for your particular receiver circuit, tubes and loud speaker.* DIS-TON is noiseless in operation no crackles and popping such as you get with run down "B" Batteries no hum of any kind to distort the finest aria or drown out the faint signals from distant stations. A self-contained electrical instrument using A C

DIS-TON is trouble free the special Trans-Filter Unit is sealed Without attention of any kind after simple initial adjustment to in, protected against tampering and deterioration. It can't wear your set DIS-TON insures you the equivalent in performance of out. Consumes only eight watts from the nearest lamp socket new "B" Batteries every time you listen in. and puts your "B" load on the big, powerful, carefully watched DIS-TON requires no change in the internal wiring of your set to generators of your central station. You can rely upon DIS-TON secure either utmost efficiency or entire safety. Accidental im- to give you the best from your receiver. proper connections can't result in tube "burn outs."

DIS-TON Know how much DIS-T5N adds to radio DIS-TON KITS complete Essential Parts for for ready The advantages that DIS-TON will give you are outstanding and unusual. You operation Home Builders 110 volt, 60 cycle have the opportunity to verify them -all on your present receiver. A DIS-TON 110 volt, 60 cycle $10.00 $28.50 demonstration is yours for the asking. Send for Leaflet B and full details as the Other voltages and Other voltages and first to radio this season. cycleson application step greater enjoyment cycleson application

RADIO PRODUCTS, Inc. Dept. RB Richmond, Ind.

*Dis-TON will not make a "single tube" into a "super-het," but it will modernize the performance of any of the good, older receivers in an amazing fashion.

if Tested and approved by RADIO BROADCAST 242 RADIO BROADCAST ADVERTISER

therefore learn how to operate without causing this interference.

ADJUSTING A REGENERATIVE SET IF YOU will take the trouble to observe the * rules which follow, you will obtain greater satisfaction and enjoyment from your radio receiving set, and at the same time cause mini- mum annoyance to your neighbors.

Practise on (1) tuning powerful stations first and do not try to pick up weak distant stations until you become expert. (2) Use both hands, one hand for the regenera- tion control and the other hand for the tuning control.

(3) Keep the regeneration control always just below the point of oscillation, your set is then in the most sensitive condition. This is the reason for using your two hands for tuning. (4) If your set then accidentally breaks into oscillation, turn back the regeneration control at once. (5) Do not try to find a station by the whistle. If your set is tuned just below the whistling point, the signals will come in clear and your regeneration control can then be tuned a little further to increase the volume. (6) Do not force regeneration in an attempt to obtain loud speaker volume from a set not designed for the purpose. (7) Do not force regeneration in an attempt to hear stations beyond the range of your set; be content with those you can hear. Smallest Uniform Condenser really Frequency The fact that you once heard a distant station on Easily Fits Into Present Sets your receiving set is no indication that you can hear this station regularly, for occasionally a size illustration above shows Samson Condensers are but radio broadcast from a distant station is re- z/*"1 diameter FULL with plates fully extended half to a third the ceived with extra strength due to some freak size of others. condition. When you have tried to tune-in to a You can station in the correct manner for a minute or easily increase the selectivity of your present receiving set having and do two and are not able to hear it, do not ordinary condensers, away with the crowding of station readings unduly increase and where 85 out of 100 come in below 50 on dial by using your regeneration persistently wiggle your dials, for in so doing you may be causing annoyance to some other broadcast Damson listener who would otherwise be able to hear this distant station on his ^^ l/niform frequency multi-tube set. If you are not satisfied with the range your \Jondensers present receiver is giving you and providing local Samson Uniform Frequency Condensers are built to a tolerance of 1/1,000 conditions are satisfactory, the only remedy is a inch, silver plated all over for high surface conductivity, and in addition more sensitive receiver or the addition of more have gold plated rotor and stator plates to prevent oxidization. tubes to your exisiting set. Don't at your These neighbors' expense, try to force your receiver. grounded rotor type instruments have losses lower than the average Besides being unfair to your are laboratory standards. This condenser, due to its design does not have the neighbors, you defects caused also spoiling your own quality. by either solid metal or dielectric end plates. 500 mmf., You can accordingly assist in $7.00; 350 mmf., $6.75; 250 mmf., $6.50. eliminating these whistles by: SAMSON ELECTRIC COMPANY to Manufacturers Since 1882 (a) Learning operate correctly yourself. (b) Not allowing children, who are not old Canton, Mass. enough to understand the correct method of Salt* Representatives in Thirty Leading American Citie* i operation, to cause interference from your set. (A crystal set causes no interference).

THE LICENSE

A LL radio receiving sets in Canada are re- quired, by law, to be licensed. Licenses are issued and Why not subscribe to Radio Broadcast? By the year only $4.00; or two yearly are required to be renewed on the first of each years, $6.00, saving $2.40. Send direct to Doubleday, Page & Company, April year. They may be obtained for one dollar from local Radio In- Garden City, New York. spectors, many Post Offices, many Radio Dealers, or from the Radio Branch, Department of Marine and Fisheries, Ottawa, Canada. The proceeds of the license fees are used to ACME maintain an inspection staff for the administra- CHARGERS tion of radio and for the improvement of radio conditions in the Best by Test Dominion.

$Q50^ minus bulb

For the listeners who are desirous Your dealer can get it for you benefit of of obtaining this article in circular form, it should be stated that THE ACME ELECTRIC & MFG. CO. copies may be had, on request, from the nearest Canadian Radio Inspector, or direct 1410 Hamilton Avenue Cleveland, O. from the Radio Branch, Department of Marine and Fisheries, Ottawa, Ontario, Canada.

Tested and approved by RADIO BROADCAST RADIO BROADCAST ADVERTISER 243

"SELF-ADJUSTING"Rheostat A BASIC Need in Every Circuit BECAUSE AMPERITE not only modernizes any set it keeps it modern.

1 Eliminates Hand Rheostats, thereby 5 Prolongs tube-life by keeping fila- simplifying control. ments at a constant temperature. 2 Permits use of the latest of types 6 No filament meters needed. tubes or any combination of tubes. 7 Brings the most out of each indi- 3 Simplifies and reduces set-wiring, vidual tube automatically no thereby making for greater pactness and avoids losses. guessing. 4 No moving parts, hence no grinding 8 Makes every set-owner a master clear and full tones. operator, no knobs to turn.

Write today for FREE Hook-Ups

Sold Everywhere . 1 complete with mounting AMPERITE is used in every popular present-day construction set. Why? Because of its many outstanding exclusive features, and because it solves the perplexing problem of tube-control COMPLETELY and AUTOMATICALLY. For the new tubes: Obsolete Amperite No. 112 for the UX-112 and CX-112 Amperite No. 120 for the UX-120 and CX-120 (Company Depi. R.B.-13 50 Franklin Street New York City Mf's of "TUNE-RITE" Straight-Line-Frequency Dial Be sure that the set you buy or build is equipped with AMPERITE.

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ifiC READERS WRITE Amplionpedigree US

"Pico" Thirty-eight years ago Say Instead cf "Micro- Micro-Farad" In 1887 Mr. Alfred Graham invented and dem- onstrated the first \A7HY not adopt and familiarize the prefix practical loud speak- v above). T * er which the world had ever heard (illustrated 'pico' for 'micromiker'" wrote Mr. F. I. In 1893 -- *UB^ Graham Loud Anderson in the September RADIO BROADCAST Speakers placed upon market. In 1 894 GrahamLond (page 662). "Thus, instead of saying a 'triple- Illustration shows Speakers first used in Created by the actual the "1893 model." British Navy. Graham o-five' condenser, for an instrument of 500 transmitters applied to world 's originators and phonographs for loud micro-micro-farads, let us say 500 picos, which makers of loud speaker reproduction. oldest is correct and simple, if we once get used to it. it is only logi- speakers, In 1896 Graham Loud Speaking Naval Telephones developed and To be precise, we should say pico-farads, but we cal that the Amplion adopted by British Admiralty. could drop the farads once we get used to the unrivaled for In 1898 Graham Watertight Loud Speakers patented. Placed on many should be world. warships and mercantile vessels, throughout pico end of it." From Robert S. Kruse, techni- clarity of tone. Some on central bat- In 1903 Complete Graham Loud Speaker installations, cal editor of comes a letter us that of the countries in tery plan, erected on warships as sole means QST, informing which rule of communication. he is heartily in agreement with this idea and Amplions in- In 19OO The most extensive loud speaking naval has as favorites: stallation to date was made by Grahams. already taken steps to make it take on a Graham fitted to Included exchange system definite shape. UNITED STATES H. M. S. Dreadnought. CANADA Onwards Graham Loud Speakers applied to all sorts and abroad, and conditions of service at home Editor, RADIO ENGLAND ashore and afloat. BROADCAST, WALES in & SCOTLAND By 1919 No less than 12,OOOGraham loud speaking installations oper- Doubleday, Page Company, IRELAND ation on ships alone. Garden New York. NORWAY SWEDEN City, 1923 DENMARK In 193O (before radio In Amp- SIR: loud were in lions adopted as BELGIUM , speakers HOLLAND standard common use) "AMP- equip- 1 want to enter an enthusiastic endorsement FRANCE SPAIN LION" Loud ment by leading Speakers of SWITZERLAND produced for radio by makers of radio the idea expressed by Mr. F. 1. Anderson on Alfred Graham & Co. sets abroad. ITALY JAPAN page 662 of your September issue. a 19! "AMPLION" trade- By SOUTH AFRICA Mui mark registered. strange coincidence we received this issue on the ^Vr NEW ZEALAND exact day when we had been the AUSTRALIA In 1933 Amplions introduced into United States, Canada and other discussing countries. Quickly attained largest throughout-the-world sale extremely unsatisfactory nature of the micro- of any loud speakers. micro-farad. This letter is only to offer you In 1934 To supply demand The Amplion Corporation of America was formed to market and manufacture Amplions here. my personal cooperation in anything you would In 1935 More Amplion companies formed and agents appoint- il^TI care to do along this line, although we have al- ed world to with international throughout keep pace Jilll^ half formed a of demand. The Amplion Corporation of Canada, Lim- ready plan more general techni- ited, organized. cal cooperation. This plan has now been sub- mitted to our Executive Committee which is investigating its practicality. Very truly yours, ^|j00nBME4vrrax)nnMWfOT ROBERT S. KRUSE. The Amplion Technical Editor, QST. of!926 Radio Developments in New Zealand

VA/E ARE always pleased to hear from our ' ' readers abroad and we think that fans in Alfred Graham & Co. this country are interested to know what ON London, England pro- Alf Patentees is made in too. L There To hear this new cAmplion 'Dra- gress being foreign parts gon AR-io, if to appreciate why is a certain amount of satisfaction in knowing cAmplions, year after year, inter- (gudSpeaker that one's local station is heard in nationally lead in stiles. Six mo- THE AMPLION CORPORATION OF AMERICA regularly dels, including phonograph units, some remote spot of the globe, and perhaps a $1210 Write for interest- Executive Offices: Suite L, 280 Madison Are., New York City $42.10. certain amount of when one reads that ing literature and dealer's address. Canadian Distributors: Burndept of Canada, Ltd., Toronto chagrin such and such a station be heard Associated Companies and Agents : Alfred Graham & Co., London, England; The Amplion Corpora- may very well, tion of Canada, Limited, Toronto; Compagnie Francaise Amplion, Paris, France; Compagnie Conti- in New Zealand for example, while the native nentale Amplion, Brussels, Belgium; Amalgamated Wireless (Australasia), Ltd., Sydney and Mel- bourne; British General Electric Company, Ltd., Johannesburg and Branches; Indian States and fan, who may be merely two or three thousand Eastern and Calcutta; C. J. Christie E. Buenos David Wallace Agency, Bombay Hijo, Ayres; &, Co., miles nearer, is unable to receive it. We wonder , Valparaiso; Mestre Qc Blatge, Rio de Janeiro; F. W. Hammond & Company, London and Tokio. what percentage of East Coast fans have received KGO, KFI, and KPO, as often as Mr. Haggett has? This is a good time to subscribe for RADIO BROADCAST DOMINION RADIO COMPANY Through your dealer or direct, by the year only $4.00 WELLINGTON, NEW ZEALAND DOUBLEDAY, PAGE & CO. GARDEN CITY, NEW YORK Editor, RADIO BROADCAST, Doubleday, Page & Company, RADIO WIRES Garden City, New York. SIR: We manufacture all types. Just a few lines to express my appreciation of your excellent magazine. I have always braided Round antenna wires found it an ideal publication in every way. I Flat braided antenna wires have just received the July issue and I think it

is the best I was to of TRADE MARK REG. Round stranded antenna wires yet. very sorry learn the death of Miss Mix, as her column was of great Above in tinned enameled tinned bronze. types copper copper copper interest to us. Broadcasting here is not of a Loop wires in silk or cotton covered. Antenna supporting springs. very high order just yet, but this year will see Litz wires. Cotton and silk covered wires for set New Zealand with one of the best broadcasting Enameled wires. wiring. j services in the world. Parliament is making Write us for descriptive catalogue. provision this session for the erection of several main stations and several satellite ROSS WIRE COMPANY 69 Bath St., Providence, R. I relay sta- tions. The revenue is derived from fees to be

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J V .

Radio technicians and engineers as well as seasoned amateurs know that "General Instrument" is satisfied with nothing short of perfect precision.

For example: The General Instrument laboratories developed the eccentric type straight line frequency condenser at great expense only TO ABANDON IT!

Try to rotate an eccentric type straight line frequency condenser and note the effect on the bearing and then you will realise why "General Instni' ment" discontinued the eccentric type and created the CONCENTRIC straight line frequency condenser.

CONCENTRIC straight line variable condensers represent the latest development in condenser engineering. Observe the even distribution of weight of the rotor plate.

"General Instrument" thinks more of its reputation than the cost involved in creating a perfect instrument. Hence the CONCENTRIC straight line frequency condenser.

CONCENTRIC Straight Line Frequency Condenser

(Pyrex Insulated) The perfect instrument created by General Instrument. Type 80. STATOR

TYPE 40 THE INIMITABLE RHEOSTAT

Built only by General Instrument, this rheostat can

NOT be imitated. To get it, you must make sure PATENTED of the name "General Instrument."

OBTAINABLE AT BETTER CLASS RADIO DEPARTMENTS

^Manufacturers ofLaboratory Equipment 423 Broome Street New York City

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charged listeners-in which will be the equivalent of nearly five dollars. At the present time my company is running the broadcasting stations in this city and local companies are doing the Receiver same in the other towns, but that will cease of course when the new Broadcasting Company Superadio in course of is The (now formation) ready. reception of American stations here is achieved nightly using only single "valve" sets, and loud speaker volume using one stage of radio, de- tector and two of audio. I have heard KGO, Tubes KPO, KFI, and others a Model XV 5 using Kennedy Receiver and have logged any number of "Yanks" on a low loss set of my own construc- tion. I am at the present time building a RADIO 2 Dials BROADCAST Phonograph receiver as described in your paper. 1 expect great results from it and no doubt you will be pleased to hear how I get on with it. This quarter of the globe is excellent for reception as is evident by the long distance $56 records made by New Zealanders. At the time of writing we are expecting the arrival of Licensed Under the American Fleet here and I have Reactodyne Agreement already heard their "sigs." from Lieutenant Schnell's At last true beauty is combined with scientific design so that results short wave set. The "star" on a never before expected are now easily achieved. Loose, extravagant your advertisements means lot to us here in New Zealand. We cannot tell claims are not made for this set, which must be seen and heard to be what is the latest apparatus and whether all the appreciated. goods one sees advertised are what they are sup- posed to be, but in buying for this firm I have Results Undreamed of Now Secured never once fallen in when guided by the "star." We have up to the present only handled small handsome, Employs a radically new principle inductive reaction. Housed in a quantities of goods but we anticipate an in- compact, solid walnut cabinet with black bakelite panel engraved in deep gold- creased volume of business this year. Thordar- Produces full rounded tones with all their color and shading. Oscillations son, Belden, Na-ald, Peerless, Daven, Bell, Walnart, and Federal are amongst the lines we automatically controlled. Use of low loss S. L. F. Condensers and highly handle and we are satisfied that they are the best. Solenoid R. F. Transformers results in tremendous power without developed So you can see what a valuable guide your paper while controls, two, regulate the thunderous disturbing squeals, simple only is to us who "have no mother to guide us", as it volume to fairylike whispers, if desired. were. We all enjoy your column "As The Broadcaster Sees It" it is a scream. Sendfor circular giving engineering details why the Superadio all the success deserve with is so far ahead of present day conceptions. Wishing you you your excellent paper. Very truly, yours, Tested Tubes Now Possible R. HAGGETT J. Wellington, New Zealand. With the Superadio Dynometer Remember can now TESTED tubes you buy The O'Connor where the Superadio Dynometer is on the job. Frequency-Changer This meter is direct reading. Measures the ampli- fication factor, plate impedance, and mutual con- O'Connor Frequency-Changer, ductance of radio tube. to any Extremely easy THEwhich was described fully in the J une and Tests three tubes minute. operate. per August, 1925, RADIO BROADCAST, hascaused Special Model S-2 Amplifier $30. much comment, and we have received num- erous letters from readers who have had Jobbers and Dealers success with this circuit. By its use it is possible to convert any existing receiver to Write for details on the Dynometer, and our Superadio Dynometer equipped a super-heterodyne, and thus increase liberal selling proposition. Be the first in your with phones and plug. Price $120. in town to sell TESTED tubes. (Patents Pending) range and selectivity. Used combina- tion with a neutrodyne receiver it is possible Inc. to efficiently reduce the number of tuning DeWITT-LaFRANCE CO., controls to two, instead of the usual three. 54 burn Massachusetts Wash Ave., Cambridge, Here is a letter from an enthusiastic con- Boston Representative: Chicago Representative: structor. Martin, Hartley & Dewitt Sales Co., 99 Bedford St. William A. Welty & Co., 36 So. State St.

Editor, RADIO BROADCAST

to subscribe Doubleday, Page & Company, This is a good time for BROADCAST CONTROL OPERATORS RADIO BROADCAST Garden City, New York. who read Carl DreherVs discussion in the September RADIO Through your dealer or direct, by the year only $4.00 BROADCAST on "Microphone Placing in Studios," should not DOUBLEDAY, PAGE & CO. GARDEN CITY, NEW YORK SIR: miss "Additional Notes on Placing" to be printed Microphone I have read with interest the controversy re- in the January magazine. lative to the O'Connor Frequency-Changer, and Mexican Crystals as to its being a dud I can give evidence to the "The Catwhisker's Delight" contrary. 1 have one of the first ones made in this terri- The bar none. BEST, tory and what it did to my five-tube neutrodyne For sets, "Sil- Crystal is more than satisfying, in selectivity and volume ver Galena.'' For Re- and distance, and I had what was considered an flex "Placerite." sets, DEALERS! exceptional set before. Once used. tried, always Atlantic City, Elgin, Providence, and Pittsburg Send for our big new live 3 for come in between two degrees on the dial, and A 40c Each, $1.00 Catalog. Contains hun- with no interference. ^ for DeForest, dreds of standard nation- Special joe Detroit and Toronto come in within half a ally advertised sets, users. You are next. on the dial, also with no interference. 1 am 70,000 kits and degree FREE parts. Fort Worth and Dealers write Use your letterhead getting nightly now, practically Diagram for all stations above 500 watts in power. H. D. HATFIELD SON ultra-selective & Crystal circuit Very truly, yours, 1762 Vermont Ave. free with 3 C. F. RODGERS, crystal! at $1. Hollywood California Conneaut. Ohio.

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/rety/mrtj l/mE Marks a new era in Radio progress Sweeping country like a tornado Fans welcome it with open arms * Irresistible demand growing by leaps and bounds KARAS Started It - and KARAS Is Carrying On ! ! When we sprung the Karas Orthometric Condenser on a KARAS Orthometric Condensers could not be thrown restless, hungry radio public we knew we had started together. It took months to train gangs to build them something. But we scarcely expected to be snowed under with the absolute precision KARAS demands. So tens of with such a literal avalanche of orders. thousands had to wait or buy other makes, hurriedly We inaugurated Straight Frequency Line Tuning at the assembled to supply the demand we had created. moment. Radio Fandom was hun- psychological waiting NOW after months of preparation we are able to pro- for new. And here was grily something something not duce enough KARAS Orthometric Condensers to take new but so so only perfectly simple thoroughly scien- care of at least a fair share of the demand. This an- tificso downright sensible, that everyone wanted KARAS nouncement is an apology to those who were disappoint- Condensers at Orthometric once. ed. A note of thanks to those who have waited. And a Our scheduled production was like a drop in the bucket. promise of revelation to those who have not yet discov- Buyers pleaded cajoled even threatened. Our plans ered the marvelous advantages of Straight Frequency- were doubled, trebled, quadrupled. But it all took time. Line Radio Tuning. How KARAS Orthometric Condensers Simplify the Tuning of any Radio Set \o to "'

Culinary Condenser Arrangementof Wavelenglhs Straight Line Wavelength CondenserArrangement of Wavelengths on Dial Ordinary straight capacity condensers With straight -line -wavelength con- The New Scientific Karas Orthometric crowd 70 of the 100 wave lengths densers 57 of the 100 wavelengths are Condensers insure absolutely equal sep- into the first 30 points of the dial. crowded into the first 30 pointsonthediaL aration on the dial of all wavelengths throughout the entire broadcasting range. Sizes and Prices Government regulations separate all stations by an equal interval of 10 kilocycles. Old type 23 plate, .0005 Mfd., $7.00 condensers straight line capacity and straightline wavelength warped this uniform arrange- 17 plate, .00037 Mfd., 6.75 ment crowding a lot of low wavelength stations into the first few degrees on the dial. Diffi- 11 plate. .00025 Mfd., 6.5O culty in tuning confused interference of these were the 5 plate, .0000972 Mfd., 6.50 heterodyning garbling programs results. KARAS Orthometric Condensers give low wavelength stations the same equal sepa- ration as the high ones. It is the last word in making real selectivity possible. The illustra- tions above tell the better than words. Note the story Karas Orthometric Condensers are both and Made entirely of brass long theoretically, mechanically perfect. plates patent leveled and securely bridged to insure permanent rigidity and alignment. joint soldered. Grounded eccentric Every frame and rotor. Adjustable cone bearings. Spring copper pigtail. In short, so beautiful a job that one engineer, plates on seeing the condenser for the first time, smilingly inquired. How many jewels?" As proof of their mechanical and electrical efficiency, Karas Orthometric Condensers will hold a charge for from 6 to 8 hours, as against one hour to an hour and fifteen minutes for ordinary condensers.

If your dealer hasn't secured a stock of Karas Condensers Order on this 4043 N. Rockwell St., Chicago Coupon ! Please send me Karas Orthometric Con- Most good dealers every- where. sell Karas Orthomet- densers, size at $ each. ric Condensers. If your I will pay the postman the list price, plus postage, on deliv- dealer happens to be one who ery. It is understood that I have the privilege of returning hasn't secured them,we will sup- these condensers any time within 30 days if they do not prove and will refund at once. ily you direct on our 30-day entirely satisfactory, you my money oney-Back Guarantee. Just fill in and mail this coupon at once. Send no money. Pay your post- Name man on delivery.

Address _, KARAS ELECTRIC CO., For more than 30 makers PRECISION Electrical Apparatus Dealer's Name... years of end _ If you send cash with order.we'll pat agpotpald

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