RADIO BROADCAST ARTHUR H. LYNCH. Editor APRIL, 1926 WILLIS K. WING, Managing Editor JOHN B. BRENNAN, Technical Editor Vol. VIII, No. 6

EDITORIAL SCENES

H. MARRIOTT is one of the "old men of ROBERTradio" in the United States and his articles about "How ' - Radio Grew Up" seem to please both old and new radio folk. Cover Design From a Painting by Fred J. Edgars The first article in the series he is writing for RADIO BROADCAST appeared in December, 1925. However much we may marvel - - at Frontispiece Listening-in Petyn 642 now at the accomplishments of the amateur in throwing a faint short-wave signal half way around the world with his simple How Radio Grew Robert H. Marriott 643 apparatus, there is still much of the remarkable in the accom- Up plishments of the early radio workers, and there is no one better able to tell about it than Mr. Marriott. There are other arti- What Happened During the 1926 International Tests cles to follow by him. Willis K. 647 Wing A LTHOUGH the International Tests are considerably be- /!. hind us in this rapidly moving radio world, the corres- The March of Radio -J. H. Morecroft 652 pondence from radio listeners all over the United States and from foreign countries still continues to bombard the office. For those who listened in vain for a peep on a foreign wave- The Short'Wave Receiver Contest < 657 $500 length, the review of the results of the Tests on page 647 of this issue should attract attention. A letter just received from The Tube and Its Best Uses Keith Henney 658 a woman in Iowa is especially interesting. "To settle an ar- gument with my husband," she writes, "will you please tell me whether or not the came from The "Aristocrat" Receiver - 664 following program any foreign station?" The program in question came from Bournemouth, and since that station was added to the list at the last minute, Radio Sets for Light Keepers - - - 666 she, among many listeners, did not know they were on. We settled the argument.

- - The Listeners' Point of View John Wallace 667 third in the series of Keith Henney's valuable articles THEon tubes appears in this number. The previous two ap- As the Broadcaster Sees It - Carl Dreher 672 peared in the December and February issues of RADIO BROAD- CAST. "The Tube and Its Best Uses" is specially designed to F. F. Drawings by Stratford answer all sorts of questions on the practical use of the tube in radio circuits, and it was written in a large measure to answer definite which came to our office. How a Portable B Battery Transmitter Works inquiries By the Laboratory Staff 678 /DOMING numbers of RADIO BROADCAST will have much of \J interest to every sort of reader. One wishes that space did not us from in this issue some of the Filament Resistance B. Brennan 682 limitations prevent including The Use John of these articles which have been omitted for that reason. In an early number, there will be another of the home laboratory arti- - - - Cutting out the Locals - H. E. Rhodes 686 cles, describing a very useful wavemeter wit,, complete instruc- tions on how to use this valuable device in the home laboratory. is article H. E. Rhodes on de- The Grid and Answers 696 Then there another by wavetraps, Questions scribing a number of valuable types, which will be a great help Coil Dimensions for the "Universal" Receiver to those who are having their own difficulties with a receiver Eliminating the Reflex in the Roberts Circuit which is not selective There will be more informa- How to Calculate Capacity in Series or Parallel enough. A Three-Tube R. F. Circuit with Impedance Amplification tion on short-wave transmitters that subject which has proved widely popular with our readers. Edgar H. Felix has article on how to learn the code which "Now, I Have Found" - - - - 702 written a very helpful many a mystified struggler with the Continental dots and in Cone Speakers Improving Reproduction dashes will find of value. The article C. How to Provide a Counterpoise System great by J. Jensen 4 ' "Can We Forecast Radio from The Silver "Model 1926 Receiver 1 in the April number, Reception A Coil Winder for Diamondweave Coils the Weather?" has stirred up no end of interest and discussion. A Battery Throw-over Switch after the the Associated Press car- Economical Sub'panel Brackets Shortly magazine appeared, ried a story about Mr. Jensen's conclusions. Mr. Jensen's other in the same field to tell Short Wave Stations of the World 708 article has inspired investigators us of their work and we hope soon to print the conclusions of some of these men. A Key to Recent Radio Articles E. G. Shaltyiauser 710 on the $500 short-wave receiver contest MANUSCRIPTSare piling into the office, and those who have not yet What Our Readers Write Us 716 become actively interested in the problem should turn at once to page 657 and set their brains to work. W. K. W.

0*=

& Co. Page & Co. Doubleday, Page Doubleday, Doubleday, Page & Co. Doubleday, Page Sr Co, MAGAZINES BOOK SHOPS LORD & TAYLOR BOOK SHOP OFFICES OFFICERS COUNTRY LIFE PENNSYLVANIA TERMINAL (2 Shops) GARDEN N. Y. NEW YORK: CITY, F. N. President WORLD'S WORK WALL ST. AND I66WEST 32NDST. DOUBLEDAY, BUILDER 38 NEW YORK: 285 MADISON AVENUE GARDEN & HOME GRAND CENTRAL TERMINAL A. W. PAGE, V ice-President RADIO BROADCAST BOSTON: TREMONT BUILDING c , I 223 NORTH STII STREET SHORT STORIES NELSON DOUBLEDAY, ^'ice-President I 4914 MARYLAND AVENUE CHICAGO: PEOPLES GAS BUILDING EDUCATIONAL REVIEW 20 GRAND AVENUE RUSSELL KANSASu'.v, . c CITY,r,. ) 9 SANTA CAL. DOUBLEDAY, Secretary LE PETIT JOURNAL SyREET BARBARA, j ^ WEST 4?TH EL Eco CLEVELAND' HIGBEE Co. LONDON: WM. HEINEMANN LTD. S. A. EVERITT, Treasurer FRONTIER THE SPRINGFIELD, MASS. MEEKINS, PACKARD^ WHEAT OXFORD UNIVERSITY PRESS Asst. Treasurer WEST TORONTO: JOHN J. HESSIAN,

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Copyright, 1926, in the United States, Newfoundland, Great Britain, Canada, and other countries by Doubleday, Page & Company. All rights reserved. TERMS: $4.00 a year; single copies 35 cents. 640 RADIO BROADCAST ADVERTISER 641

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VOLUME VIII NUMBER 6

APRIL, 1926

The Period 1872 to 1897 Hughes, Dolbear, Hertz, Branley, Lodge, Tesla, Popoff Marconi's Early Life Wireless is First Put on a Commercial Basis By ROBERT H. MARRIOTT First President, Institute ofRadio Engineers

CHAPTER I of "How Radio Grew coherer method of reception and went back his invention as a mode of electric com- Up" we rapidly traced the growth of to the telephone and detector method. munication, and said in the description, radio science from its earliest stages Hughes made his demonstrations to "Communication may thus be established INfrom the time when Luigi Galvani con- fellow scientists who appeared to be bent between points certainly more than half ducted his researches in 1790, probably on discouraging him, and years later he a mile apart; but how much farther I cannot " knowing little about what he was actually said, I was so discouraged at being unable now say." doing, through the researches of De Salva, to convince them of the truth of these It looks now as though both Hughes's and of Morse, and of Maxwell. The electro- aerial electric waves that I actually re- Dolbear's devices were pretty fair radio magnetic induction experiments of Faraday fused to write a paper on the subject ." devices for that time; but apparently those were also described, and the story concluded In 1882, Professor A. E. Dolbear, of equipments were not deliberately designed with one Loomis, who, in 1872, took out a Tufts College, built a transmitter and a and operated on the basis of the now patent for a special apparatus designed to receiver, with antenna and ground, that accepted electro-magnetic wave theory of utilize electricity collected from the atmos- apparently must have operated according Maxwell. phere for transmitting purposes. Taking to the electro-magnetic theory. On Oc- Following Hughes and Dolbear, we next up our story at this point (where it was tober 5, 1886, he was granted United States come to the exponents of the earlier Max- dropped in the December, 1925, RADIO patent number 350,299. He described well theory. The first of these is Henrich BROADCAST,) the first new name in Hertz, a German scientist, who, in the series is that of Professor D. E. 1886, proceeding on Maxwell's Hughes, who, in 1872, managed to theory, built and used a carefully transmit and receive intelligible tuned radio transmitter and receiver. signals over a distance of a quarter However, it could not be heard of a mile, using, for receiving pur- enough to do much more than serve poses, both coherers and microphonic as proof of the Maxwell theory, be- detectors. cause the detector was insensitive. He described his devices before the Sir William Crookes, in discussing Royal Society on May 8, 1878. Hertz's apparatus, said, quoting from During his experiments, he walked the Fortnightly Review, London, Feb- up and down Great Portland Street ruary, 1892, "Here, then, is revealed in London with his microphonic de- the bewildering possibility of tele- tector and telephone receiver, and graph without wires, posts, cables, or it was at this time that he got signals any of our present costly appliances." up to a quarter of a mile or more HERTZ THE FATHER OF RADIO ? from his transmitter. Had he per- sisted with his apparatus, and if it scientists and other folk had been possible to employ at that SOMEwho have studied the history of time a present day publicity agent, radio and who are not biased by radio might have gone into public nationality or by some company's service many years earlier than it pay roll, are inclined to say that radio did, for some of the accounts in- is a product of evolution; while dicate that his apparatus was every EDOUARD BRANLY others prefer to say that radio was bit as efficient as apparatus used invented. As a rule, those unbiased French scientist who made a very valuable contribution seventeen later. In this coun- ones who to it was in- years wireless telegraphy in designing a detector known as a prefer say try we quickly abandoned the later coherer. It was later improved by Sir Oliver Lodge vented, give the credit to Hertz. 644 RADIO BROADCAST APRIL, 1926

the product of German, French, English, American, and Russian scientists, arrived at by sticking to the Scotchman's (Max- well's) theory.

MARCONI'S EARLY LIFE

this radio development was WHILEgoing on in the scientific circles of the world, young Marconi had been taking a course under science teachers at Leghorn and Bologna, and became interested in radio in 1895, when about twenty-one years old. He had means and influential connections in both Italy and Great Britain. He came from Italian ancestry on his father's side, and Irish ancestry on his mother's side. In 1896, Marconi went to England and NIKOLA TESLA GUGLIELMO MARCONI filed a patent in which he described the in in Whom Mr. Marriott describes as a sales Was born Austria-Hungary 1857, Serbian Hertz-Branly-Lodge-Tesla- Popoff devices engineer. by race. It was originally intended that he He studied and conducted his early experiments and a special form of spark gap that had should be trained for the clergy, but he developed at the University of Bologna in Italy. In 1899 been the Italian scientist scientific tendencies instead. He came to designed by he succeeded in communicating across the America in 1884 and immediately entered the Righi, which gap was not necessary but English Channel for the first time, and in 1901, Edison works, afterward starting out on his could be used as a substitute for the one across the Atlantic Ocean. He was awarded own. In he invented methods the Nobel Prize for in 1893 of wireless used by Hertz. Then he commenced Physics 1909 transmission demonstrating what was actually known about radio up to that time, to government didn't. Also, as part of the promotion In 1891, Edouard Branly, a French representatives and to business men, to scheme for getting money, Marconi was scientist, made a more sensitive detector newspaper and magazine writers. His advertised as deserving the honor for what than that used by Hertz, intended for use demonstrating extended radio from college the scientists had done, making him appear in the latter's receiver. This detector was environment to political, military, and as a profound scientist and almost super- called the Branly coherer. It consisted of mercenary circles. By the middle of 1897, natural inventor. particles of metal that would stick together business men had become sufficiently inter- The scheme was to make it appear that when affected by radio currents, and would ested to form a 100,000 company for Marconi had invented radio and thereby then pass a battery current. Sir Oliver exploiting radio. get a world wide radio patent monopoly. Lodge used the Hertz-Branly combination, Marconi played the part of a salesman, That was the beginning of many dupli- but added a tapper that automatically de- and, as is still often the case where scientists cated attempts to advertise inventions and cohered the coherer after a signal. and salesmen are involved, the salesman inventors for the purpose of getting a In 1893, Nicola Tesla proposed that high got money out of it while the scientists monopoly of radio, or to sell stock. It has antennas and a been tried more or ground connection less right up to this be used at the sending very minute. In the and receiving instru- United States, how- ments to get the great- ever, the patents were est possible distance. shown up for what In 1895 Vladimir they were worth, or Popoff, a Russian, avoided by making added antenna and other devices that ground to the Hertz- would serve the same Branly - Lodge com- purpose. bination, and gave The virtue of the demonstrations to Marconi Company's students and scien- advertising was in the tific people. The dis- publicity it gave to tances covered grew radio and not in the with these successive claims they made for steps. themselves. That By 1894, wireless, publicity started that is the induction quite active develop- system like that Fara- ment of radio in sev- day had used, and the eral countries. It put conduction system more money and peo- which Morse had ple into the develop- demonstrated, had ing of this so-called been successfully and new science. The repeatedly used to THE CATALINA SENDING STATION advertising telegraph over dis- brought radio to the Located at Avalon, about twenty-five miles from the California Coast station. Until Mr. Marriott tances to three attention of in up erected this station there was no means of communication with the mainland except by means of people miles or more. The the boat service which was not at all reliable, especially in bad weather. One of the first uses to all walks of life, in- Hertz-Branly- Lodge- which this wireless was put was to receive the result of a big fight which took place in San Francisco. cluding numerous un- Skeptics doubted the authenticity of the wireless reports and even after they were confirmed, various Tesla- Popoff combi- attached young theories as to how the messages were actually received were advanced. Some said that carrier nation would - be scientists apparently pigeons were used. Others said they saw a man in a small boat land on the Island with the news. worked best. It was Another theory was that signals by means of powerful lights were sent from the mainland to Catalina and engineers, who, APRIL, 1926 HOW RADIO GREW UP 645 like Marconi, as yet dangerous Indians. had no scientific or Scientists, with reli- engineering reputa- able incomes and tions to lose, and reputations that could take therefore, might get sunk na- in this a chance new turally were afraid field. to go into radio. It became obvious However, there to many that radio were quite a num- could be useful if ber of young men properly applied. who had been given Its apparent possi- scientific training, bilities made it an and who had not easy thing for stock made any scientific to sell stock jobbers or engineering repu- in radio companies. tations that could They were inclined be lost. Some of to depart very them were adven- widely from the kind turous enough to go of rules laid down in into radio then, and Christian Sunday a few still survive. schools in disposing The writer is one of of their stocks, how- these young men. ever. Radio was an After 1897, the obviously fertile works and workers field, but without AN EARLY DETECTOR became so increas- immediate returns ingly numerous that Is shown in this photographic reproduction of the sketch and description of those made by Mr. in it. It contained some of the es- Swenson (Mr. Marriott's able assistant) to Mr. Marriott's specifications. These were used in the only or less some more California-Catalina Island circuit for several years. They consisted of converted spherometers sence of them can be

C. S. KEMP, AN EARLY ASSISTANT OF SENATOR MARCONI Photographed in England with the apparatus used by Mr. Marconi in his experiments at Bologna, Italy, in 1895. The copper plate at the top is the antenna used for short distances, while for greater distances, kite balloons ten feet in diameter with a copper antenna wire attached, were employed. The telegraph key is at the right, the large induction coil shown in the center operating from batteries, furnished the high-frequency energy 646 RADIO BROADCAST APRIL, 1926

given here. Radio stations began to bob up in various parts of the world like mush- rooms, and like mushrooms, they did not last long in any one place; as a rule because they didn't pay expenses, and also because a great many of them were temporary stations erected purely for demonstration purposes, devoted to showing the possibili- ties at that place, or to sell stock. In 1902, the writer succeeded in establishing a radio circuit between Catalina Island and the mainland of California, the first in the United States that stayed put, although several circuits had been tried before that. That circuit continued for twenty-one years, becoming a radio telephone circuit in its later days. The use of telephony killed it, for too many uninvited folks were able to listen-in. The steamship companies were slow to install radio on their ships. The directors of the companies had too many other places where they wanted to put their money. The captains likewise did not want it because, without it, they were kings between docks, but with it, the owners might play king and give them orders. A la<-ge proportion of the first ship A 1902 COMMERCIAL RADIO CIRCUIT radio stations were established on board free The wireless telegraph installation at Catalina Island, made by Mr. Marriott and his assistants. at the of charge to the steamship companies. The switchboard right controlled the dynamo circuits for light and transmitter The switchboard in the back carried two remote The United States law which compelled power. control switch arms which switched the antenna from "send" to "receive". The box bearing the ships to be equipped with radio, took effect spark rods is a large induction coil capable of giving a 2O-inch spark but actually de- in and caused a increase in a 1912, large livering f-inch spark when connected to the antenna. The piece of paper covers a radio on vessels, and also resulted in some mechanical interrupter, which, at the time the picture was taken, was a secret of the old captains recalling for service all the cuss words had they mentally vo- spector. After a captain's big noisy kick gotten along without wireless up to date cabularized during, perhaps, forty years at was divested of its profane trimmings, so why shouldn't he and everybody else sea. The writer had intimate contact with about all it amounted to was a statement continue to get along without it. All the this of when the law to effect aspect radio, because, the that he had sailed the seas radio inspector had to say was, "Maybe went into he it effect, helped enforce at ever since the time when vessels were so, but if your radio isn't in proper working New York as United States Radio In- the that he pushed along by wind, and had order before you leave port I will have to report it, and you will be liable to a fine of five thousand dollars." Not many words, but they were effective. The value of radio as a protec- tion against the loss of life and property, and the failure of steam- ship companies to avail themselves of it, made the law necessary. Had there been a radio monopoly, this law would probably have been all the more necessary because the monopoly would have undoubt- edly held up the prices, and steam- ship owners would have fought harder against its enforcement. The United States took the lead in the production of the best de- tectors and receivers; Germany took the lead in the production of the best transmitters. Receivers and detectors were inexpensive to build, as compared with trans- mitters. This was what probably caused the various workers in the United States to advance rapidly in making the best detectors and receivers. By the time the Euro- War started in however, THE RECEIVING EQUIPMENT pean 1914, the United States was the catching Of last Santa Catalina public service station, which was closed in July, 1923, as its traffic was listened-in to with in first by many outsiders. The receiving loop may be detected in the background. A submarine cable was substituted up Germany making for the radio link class transmitters. A Complete Report of the Plans, Their Progress and Success What Stations Were Qenerally Heard How Bloopers Spoiled Reception The Qreat Popularity of the Regional Broadcasting Experiment By WILLIS K. WING

ANY old wives' tales are common special long distance tests is apt to be less tinental cooperation was as general and complete knowledge about events which occur ardent than here, where the listening period has as it was. And Mr. Tripp was untiring in his in the dark of the moon. And by never been later than midnight, Eastern time. efforts to make the many complicated arrange- the same token, things which happen ments LARGE NUMBER OF STATIONS INVOLVED necessary. during the full moon must take their chances of On this side of the Atlantic, the greatest success. The third of the International Radio DUT in of these the number of stations ever to take ^ spite handicaps, foreign broadcasting Broadcast Tests took place during the fullest arrangements for the Tests went forward part in a concerted plan of this sort were on of full moons, we remind the superstitious, and with great completeness and more foreign sta- the schedule. There were the 37 Canadian if that be any comfort to those who failed to tions were listed in the schedules this year than broadcasting stations, some 550 American broad- hear signals from the foreign broadcasters, all of have ever taken part before. John Scott- casters, 1 6 Mexican stations, 36 Cuban broad- that gentry are free to make the most of that celes- Taggart, editor of the British Radio Press casters, one station in Porto Rico, one in Lima, tial condition. For to review the Tests briefly, publications was appointed foreign director of Peru, and three in Argentina taking part. a comparatively small number of American and the Tests, and through his good offices and those The cooperation of the Cuban stations was Canadian listeners heard broadcasting stations of his able assistant, Percy W. Harris, editorial secured by Mr. Frank H. Jones, owner of sta- on the other side of the Atlantic. If that is the manager for those publications, the work went tion 6Kw at Tuinicu. The cooperation of the only measure of failure, the Tests were a failure. forward. On the Continent, the arrangements American broadcasting stations was practically However, the Tests this year, lasting for an were in charge of Dwight K. Tripp, a former complete with the exception of several of the hour for seven days, included but five days of member of the editorial staff of RADIO BROAD- California stations, notably KNX at Hollywood transmission from transatlantic stations. The CAST, who is now residing in Paris. Mr. Tripp and KFI at Los Angeles. The operators of KFI other two days, as everyone knows, were devoted worked in close cooperation with Arthur Bur- it was announced, felt that their individuality to distance receiving trials on the North and rows, head of the newly formed Bureau Inter- would be greatly limited by participation in the South American continents. And in those two national de Radiophonie at Geneva. Tests and confidently undertook to analyze days, the average listener probably heard more Although the engineers of all the Continental the desires of all the radio listeners within range stations on this continent than he had ever broadcasting stations have, for the past few of their five kilowatts, and decided, to the tune heard before. The genuinely new feature of months, been conducting some special late of wide publicity, that they would remain on the the Tests proved a great success. broadcasting tests of their own, in the effort to air during the silent periods. They stated that The plans for the Tests were published so solve the problem in international heterodyning the chances of California listeners for hearing completely in newspapers in this country and between stations which is now very serious, they foreign broadcasting was very slim, and to that in Canada, that there is no point in completely entered into the spirit of the plan and assumed confident assertion was added the confession reviewing them here, for no monthly magazine the additional burden of broadcasting for an that theirs was in part a commercial station, can hope to compete with a newspaper. But hour several nights of the Test at the unpleas- devoted to selling time on the air, and that they the 1926 Tests were the third to be held. The antly early hour of four o'clock in the morning, saw no reason for making any financial sacrifice. first Test was held in November, 1923, and their time. It was chiefly through the fortunate Our records show that a number of listeners involved only the stations of the British Broad- official influence of Mr. Burrows that the Con- in Oregon and Washington did hear fragments casting Company, abroad. The sec- of the foreign programs, a remark- ond occurred in November, 1924. In ^^ able receiving record. A very large that, the British stations and broad- number, comparatively speaking, sev- casters in Spain, Italy, France, and heard OAX at Lima, Peru and eral the Aires stations. Belgium took part. The third an- of Buenos nual Test was to have been held in The sentiment quoted from the let- below is similar to that November, 1925, but was postponed ter printed to January, 1926 in order to take contained in a great many letters advantage of what was fondly sup- and telegrams which came into the posed to be better weather condi- office of RADIO BROADCAST both tions. during and after the Tests. There is always plenty of enthu- siasm for Editor, RADIO BROADCAST, international broadcasting & from this side of the Atlantic, but Doubleday, Page Company, Garden City, New York. the desire for a special Test of this SIR, sort is not so great on the other side 1 am a radio dealer and a fan as and in of the water, especially Eng- well. May we not in some way en- land, where there are probably more ter protest against California sta- active listeners than in any of the tions remaining on the air during Continental countries. Owing to the quiet hour Sunday night (Janu- the Tests? I think the difference in time, it is possi- ary'24th) during I them all 1 like Cali- ble for any European listener to sit picked up. fornia, but I like them to shut up up a bit after twelve at night, and if at least once a year and I am sure he has a sensitive receiver, tune-in I speak the sentiments of many an occasional American station. more of your readers and fans in So that when the special Interna- this locality. tional Tests are arranged, with THE SHORT-WAVE OUTFIT IN USE AT 2 GY Very truly yours, for American sta- W. M. CURTRIGHT, listening periods During the International Tests, a 40- and an 8o-meter transmitter were tions at from three to four o'clock Flat River, Missouri. used constantly in checking receiving conditions with amateur operators in the morning, European time, the in this country and in Europe. Many reports of reception were handled would be served in desire on the part of foreign fans for by this short-wave link No purpose 648 RADIO BROADCAST APRIL, 1926 embroidering this controversy, except to add, in ing the Test Week one of the most active we tance work, so several members of the staff fairness to the Pacific Radio Trade Association, have ever witnessed, and we have been in more took sensitive receivers to Riverhead, Long who failed to cooperate positively in the national than one metropolitan newspaper office at World Island, where it was thought that the air would United States arrangements, that they finally Series time, or on the occasion of a big disaster. be free from radiating receivers and their havoc. agreed to recommend silence for the West coast A large number of official listening posts were Even there, miles from the nearest house, the stations even though they were in highly active appointed by RADIO BROADCAST and their bloopers got in their furious work. to the And during the first reports, sent in by mail, telegraph, and by the opposition plan. THE BUSINESS OF VERIFICATION few nights of the Tests, some of the Pacific coast short wave amateur radio link with our experi- stations did not keep silence, but in the main, mental station 2 GY was of constant help in from listeners in this country their insurgent tactics caused no national radio determining how receiving conditions were in REPORTSwent chiefly to the local newspapers, to calamity. Our judgment that radio listeners all parts of the country. Many radio manu- the broadcasting stations, and to radio manu- there, and elsewhere, wanted the Tests to go facturers had special receiving stations. The facturers. Many newspapers furnished verifica- through as planned, whether or not the in- National Association of Broadcasters appointed tion cards to successful listeners. Telegrams dividual felt he had a chance of hearing Europe, a listening committee, headed by Paul F. sent to RADIO BROADCAST for verification of has certainly been vindicated if our heavy Godley, of Upper Montclair, New Jersey. Mr. reports were answered the same day they were correspondence is any criterion. Godley, it will be recalled, about five years ago received, which was no small chore, considering was successful in hearing American amateur their number. Letters with details of reception HOW THE TESTS WERE ADMINISTERED transmissions, the first across the Atlantic, from have come in to our office by thousands and Tests were managed this year by a a special receiver he established at Androssan, are being checked and verified as rapidly as THErepresentative organization, drawn from Scotland. The Boston Herald-Traveller estab- possible. An official verification card is being all branches of the radio industry. A committee lished a listening station at Baker's Island near mailed to all listeners who write to RADIO was chosen from the National Radio Trade Boston, manned by several operators, and a BROADCAST whose report can be verified. Association, with Powel Crosley, Jr., as chair- meteorologist. F. R. Hoyt, of Stamford, Con- This task of verification is not easy, but its main and L. A. Nixon executive secretary. necticut set up his interesting radio recording onus is frequently broken by conscious or un- " There were other cooperating committees from apparatus at Shippan Point, Connecticut, and conscious humor. While listening last night," " in the National Association of Broadcasters and reported that he succeeded making partial reads a sample letter, I picked up a lady singing the Radio Manufacturers' Association. The records of foreign programs. R. P. Worden, on 360 meters, but she soon faded out. Can editors of RADIO BROADCAST felt in planning radio editor of the Cleveland News sent especially you tell me who it was?" This achievement, the test this year, that the interest caused by the complete reports of receiving conditions and if it is a radio affair at all, is worthy of note, and first two Tests, which were almost entirely success in the Cleveland area which were very a curiously large number of letters read just like managed from this office, had made the affair helpful. that. Verification from such meagre informa- so important that the entire radio industry In addition, RADIO BROADCAST had several tion is out of the question and there are prob- should be represented in its management. receivers in operation at Garden City, and two ably many disappointed listeners whose letters The Test Committee at its headquarters in operators were constantly on watch at station were equally bare of facts who still wonder why New York managed the American side of the 2 CY using the 40- and 8o-meter transmitting "the coveted pasteboard" was not sent them. affair and furnished the newspapers and press bands simultaneously. During the Test periods, Still others sent in confident letters announcing associations with daily and hourly bulletins. 2 GY received frequent reports from all parts of that they heard 2 LO, or Madrid, or whatnot, Certain newspapers in representative cities were the United States on receiving conditions, and "very clearly," but failed utterly to specify furnished with the official programs as received on several occasions, communicated directly their success in detail. Reports like that were from the foreign representatives of RADIO with Europe to discover weather and receiving not considered. But many others mailed reports BROADCAST. This made the task of checking conditions at the time. An article on another that were more than complete and very accurate, of foreign reception vastly easier and far more ac- page of this number describes in part some making our task almost easy. curate than in the previous two Tests. Busy those arrangements with short wave communica- The question that everyone wants to have never long distance wires, and piles of telegrams at tion. Receiving conditions are especially answered is: What success did listeners have dis- the New York office made the scene there dur- favorable at Garden City for extreme long generally, and what foreign stations were heard? There is not space enough at our disposal to list the listeners whose reports have been veri- fied, but it is possible to tell what stations were most generally heard. Station OAX at Lima, Peru.was heard by more listeners than any other, and that is no mean accomplishment, from the point of view of distance and can be pointed to with as much pride as the electrical bagging of a European broadcaster. Reports on English stations were few and far between, but all of the English stations participating were heard in var- ious parts of the United States. Almost no Cana- dian listeners heard British broadcasters. The Madrid and Barcelona stations got through to the United States very well also. Prague, M unich, Berlin, Hamburg, Brussels, and Munster were also widely reported during their transmission times. Hamburg signed off in code with the letters "h a" and one faithful reporter although he did not know the Continental code, related that he heard the name of the city and the code sign, four dots, dot dash. NO RECEIVING LOCATION PERFECT Hp HERE were spots of fair reception, although in no locality did any of the transmitting stations come in with any laudable volume. In parts of New England there were a number of successful listeners who heard both Europe and South America. There were a few, similarly in eastern New NEWS FOR THE TESTS IN NEW YORK CITY fortunate, Pennsylvania, Jersey, HEADQUARTERS and New York. A listener in Bermuda heard With L. A. of the International Radio Week Committee, wearing the telephone Nixon, Secretary Madrid and he reported that many other Ber- the Test Week, an office was set in the Hotel McAlpin, New York, where receiver. During up mudians heard LOX, and numbers of European Official Radio Week the United Press, and the Asso- official programs were given to the newspapers; were a the wires freer at stations. Moving farther west, there ciated Press were given hourly bulletins as to the progress of events. This left considerable number of listeners in southern Garden City for communications from our official listening stations APRIL, 1926 THE 1926 INTERNATIONAL TESTS 649

Ohio and Kentucky who heard fragments from days of radio when the Continent and more than that from the no thought was South American stations. Missouri seemed to given to the matter of be fortunate in radiation: when having more favorable receiving January 24, 1926 January 30, 1926 single circuits and conditions than some of her neighbor states. regeneration were from the Middle and Far West Reports were the vogue with INTERNATIONAL scattering, but in these localities, OAX at Lima, builders whose the and Buenos Aires stations seemed to get chief object was RADIO BROADCAST TEST the through quite consistently. distance. I n t h e Under Auspices of RADIO BROADCAST Magazine The unfortunate atmospheric conditions last two .years, these circuits affected reception on the other side of the ocean have <@fcf been and only four American stations were reported gradually ri junked in favor of heard our aides. Mr. in by foreign Tripp, the more advanced "it- Paris, reported that KDKA was heard there and sets. . . . Reports < Located at 1 1^ 7

PRINTABLE REMARKS ABOUT BLOOPERS

is something to be said about radiat- '"pHERE1 ing receivers, although indications are that a wide variety of remarks, mostly unprintable, have already been made about the subject during the Tests. "International radio week," says the Hamilton, Ontario, Spectator editorially, "is proving to be just a howl, instead of the howling success it was hoped it would be." And with this terse opinion about oscillating receivers everyone seems to agree. Says the Kansas City Star:

Whatever conclusion may be drawn by the committee in charge of the International Tests as to the success of transoceanic broadcasting, it can be definitely stated that the Tests demon- strated to radio listeners the menace of the radiating receiver and the ignorance of many persons in the operation of such sets. The silent hour for the hundred of licensed broadcasting stations was only the signal for thousands of unlicensed bloopers to fill the air with such howling, squealing, and sputtering as to make it a miracle indeed that any listeners THE STUDIO OF STATION SBR AT BRUSSELS were able to pick . . . SBR one of the up foreign broadcasting. was European stations very generally heard in this country and suc- Such a situation is a hangover from the ceeded also in early pushing its signals to the United States during the Tests in 1924 650 RADIO BROADCAST APRIL, 1926

radiating re- Very few of the reports of reception could be verified. ceiver, has never described a re- Reports from all over this continent showed ceiver that will that reception was bad, not only on the foreign radiate, and fre- programs, but also on American stations. at a se- " quently, KFI and KCO are, under average radio weather vere financial conditions, easily picked up in this locality," disadvantage, has writes W. W. Mulr, of Lockport, New York, refused to publish "and under extremely favorable conditions, are advertisements heard with great volume and clarity. For the featuring radiat- last four or five nights, it has been impossible ing sets. But the to pick up even the carrier wave from either is apparent- fight of these stations with a very sensitive receiving a one, ly losing set." And Wilfred at and our own Taylor, Thompson, Connecticut "Atmospheric conditions, not says: weapons with the possible exception of those in evidence strong enough to on Wednesday (January 27), were unspeakably combat a menace bad. Western United States stations were en- of this size. tirely blank, and none but the large Eastern RECEIVING CON- stations could be heard. On Wednesday, I DITIONS got through to KGO with fair speaker volume, and on that night code and bloopers were heard weather all over the lot." THEconditions And from far off North Dakota, Professor were even less E. W. Bellinger, of the University of North favorable than Dakota, at Grand Forks writes: they were during the Tests of 1924. The failure to receive foreign stations was Barratt's Here is what undoubtedly due to the extremely poor weather WHEN XX WAS UNDER CONSTRUCTION A. G. D. conditions, it being impossible to receive United *, Captain States stations with sufficient volume, and in The station of the British Broadcasting Company, using 25 kilowatts West, assistant Daventry some instances, it has been impossible to receive now furnishes service to a very large number of British and chief engineer of input good program a station. This condition has prevailed reli- single Continental listeners. But during the Tests, the signals of 5 xx were not the British during the larger part of the winter and is per- in this country, despite the fact that a 1601 -meter wavelength B roadcastin ably reported g haps the poorest reception we have ever ex- WGY has to be most for was used, a frequency which reported satisfactory Company, wrote work perienced. general relay in an article in be the Radio Times Receiving conditions can not guaranteed we Tests: in advance, and in choosing January, thought though perhaps not applying directly to the (London) of the 1924 that a great improvement would be noticed. subject in hand, is a graceful bit of praise: The second International Radio Week was Receiving conditions in the first year of the and held in November, 1924, and although agree- I want to thank you (RADIO BROADCAST Tests were rather and as West had been made with all the American good, Captain and let ments the International Test Committee) you of the British writes: broadcasting stations to "keep off the air" Broadcasting Company know that I certainly appreciate the time, money, during the periods of the European transmissions and effort that you have spent in the months The first Test Week rise to a great in- so as not to interfere with these transmissions, gave past in an endeavor to give American radio terest in transatlantic broadcasting, in fact, this the results were not, on the whole, very satis- listeners an week, and the can be referred to as the of interest interesting perhaps the beginning by music factory, as atmospheric conditions during thrill that comes once a year in hearing the public in receiving and transmit- week of the tests were remarkably unfavorable. general from across the Atlantic. ting broadcast programs across the Atlantic. It was just a matter of bad luck that this was Conditions during this week were, on the whole, RADIO BROADCAST has been working for the so, because reception during the week before fairly good and a very large number of amateurs better of its career the and the week after was very good. part magazine against during in Great Britain were able for the first time to hear on their own sets some of the broadcasting stations of the United States. Also, the reports of reception of British stations by amateurs in America were very many, of which some thousands were verified. THE POPULAR REGIONAL TESTS

from the correspondence and invec- ASIDEtive by the bloopers' performance during the Tests, the innovations of the North and South and East and West test of the last two nights of the Tests appeared to create the most interest during the period. It suggested to many listeners that here was a national arrange- ment which might be well continued in the future. Listeners on the Pacific coast rarely hear Eastern United States stations, owing to the difference in time. And stations in Mexico and South America are infrequently heard because stations here operate simultaneously on similar frequencies. During the silent period for American stations, the sonorous call of CZE of Mexico City was heard all over the United States, and the an- nouncer at that station made many friends by his thoughtfulness in frequent announcements.

"I think it would meet with the approbation THE "RADIO BROADCAST" EXPEDITION ON LONG ISLAND of thousands of radio fans," writes Henry not this Island. The short wave B. Newhall of New York, "if perhaps Setting the short wave transmitter and receiver near Riverhead, Long up but next season, regional connected the listeners with at Garden What with blooping receivers and winter, possibly during link headquarters City. hour waves could be heard at broadcasting, preferably during two periods unfavorable receiving conditions nothing more definite than strong carrier Keith similar to those of the last two nights of the that location. In the photograph, left to right: Arthur H. Lynch, editor of this magazine; Tests, could be arranged to take place every Henney, director of the Laboratory; John B. Brennan, technical editor APRIL, 1926 THE 1926 INTERNATIONAL TESTS 651

MANY LISTENERS MADE SPECIAL PREPARATIONS FOR THE TESTS A SPECIAL LISTENING STATION IN MASSACHUSETTS

The photograph shows a special antenna being put up at a good Samuel Curtis, Jr., and Leslie Barnard of the Boston American at their receiving location on Long Island. Practically every listener receiving station at Pembroke, Massachusetts. In all parts of the coun- overhauled his set, steamed up his batteries, and tightened con- try, deeply interested listeners took an assortment of receivers to the all to nections, hear the foreign signals. The overhauling is not best location near by they knew of and did their best to pull in the foreign such bad idea of the It is a regardless Tests. a good plan to go signals. Mr. J. L. Snyder, of Patton, Pennsylvania, for example, set up over a set at least every six months a receiver on the side of a mountain and reported very successful reception

two weeks or every four weeks. I should think question of silent nights. It might be wise, the matter is for the majority of listeners to it not interfere with the would seriously pro- for instance, instead of silencing all the stations decide. We believe pretty firmly in the sov- of the broadcasters if the tests grams regular in one city, so that listeners could hear programs reignty of the local station. It should be able were arranged for the mid-week so that they from other cities, to arrange for silent periods pretty generally to meet the wishes of the major- would not break in on Saturday and Sunday for all stations in one time belt to be silent, ity of its listeners in most instances. If it fail, programs. Such an arrangement is really about either for several hours, or for an We then the listeners to become vocal and the only chance now we have to give our sets evening. ought this, full well that it will start state their tests for distance. The only other way I can suggest knowing feelings. get California, for instance, is to rise up out of a storm of protest in some quarters. Our own And so we write "Finis" on the 1926 Tests my warm bed at two o'clock in the morning. feeling in the matter is quite neutral; after all Better luck next time! My bed has usually looked better than California."

There is a great deal of interest in the question of regional broadcasting, with silent periods for the other groups, and it may be that this may point to a solution of that always debated

A CORNER OF THE EXPERIMENTAL LAB- ORATORY AT WGY

With a monitoring opera- tor at the desk. This is a part of the short wave, high power transmitter installation. During the Tests, WGY used its usual power, although on the intersectional transmitting periods the last two days of the Tests, 50 kw. was employed. The station was heard in England and OP the Continent THE MARCH OF RADIO I

Past President, Institute of Radio Engineers

A Legal Test Case For Our Radio Laws

|HE government, it appears, is en- tion searched for another channel and found operate on KOA'S time? He felt, according gaged in testing the legality of the a neighboring one frequently free. to his statement, that stations such as KOA present regulations of radio broad- This new frequency selected by this had been assigned a disproportionately large casting stations and the outcome of active philosophy of force had been re- part of the total time -166 hours a week this test case will be followed with profound served, by mutual agreement, for the Ca- to two for WJAZ. Of course the General interest by all of those operating broadcast- nadian stations. Of the ninety-five avail- Electric Company could reply that they ing stations and by many of us who merely able frequencies in the present broadcast had been using the channel regularly listen. band, we have appropriated eighty-nine and possession being nine-tenths of the Station WJAZ in Chicago has questioned and left only six for Canada. Now a law, they are entitled to keep the chan- the authority of the Department of Com- "freedom of the air" exponent finds it nec- nel. merce to regulate its broadcasting assign- essary to step into one of these six Canad- The question of division of time between ments. This station is owned by the Zenith ian channels. This presents not only a the stations operated by the Radio Cor- Radio Corporation and the issue is created national, but an international radio prob- poration group and "independent" stations by Mr. E. F. McDonald, Jr., who has lem of serious proportions. is suggested in Mr. McDonald's press state- much to say about "the freedom of the Mr. McDonald has given a statement of ment and we think it brings up a very im- air." Well, we hasten to comment that his case to the press and we can easily see portant point. Someone should compare there is no such thing as freedom of the his reasons for feeling aggrieved. He has the R. C. A. group "channel-hours" to the air in the sense that Mr. McDonald uses it. invested a deal of money in his station and independent "channel-hours" and let us The tactics he has pursued in forcing legal now finds it practically valueless. He feels see where we stand on this question. We action on the part of the Department of that he has been discriminated against have twice legislated that the ether is in- Commerce are unfortunate. that he has as much right on the air as alienably the property of the citizens of the Some time ago, apparently at Mr. any other broadcaster. After having spent United States so we had better take inven- McDonald's request, his station was as- several weeks in Washington trying to get tory and see whether it is or not. signed to operate on the same frequency an assignment from the Department of Even if the combine controls 75 per cent, with KOA, the General Electric station at Commerce and not having achieved the of our broadcasting time we are not at once Denver, Only two hours a week were free, success he expected, he evidently felt that ready to denounce it. Are the people more so WJAZ was given these two, a small share he was entitled to go back home and try pleased to listen to the combine stations or of the time, we do admit. Not being con- other means. Perhaps the course was jus- the independent stations? that is the thing tent with this allotment, the Chicago sta- tified, but why bring Canada into the fray? that really counts. The people of the her share of the ether are the ones who have "the free- The photograph which forms the heading for this month Certainly meagre country shows H. I. Rothrock, Jr., of the radio laboratory. Bureau of could be left alone. dom of the air" and not the r wner of any Standards, Washington, testing the high vacuum pump used didn't for exhausting tubes. ( Harris & Ewing). Why Mr. McDonald start to special broadcasting station. APRIL, 1926 FIRST NATIONAL GATHERING OF RADIO ENGINEERS 653

The Institute of Radio be the finest in the world is worth Engineers Convention BROADCAST announces with having. RADIOregret that Mr. Arthur H. Lynch, who When did we concede that first national convention audibly has edited the from its third number to British was better than of the Institute of Radio En- magazine broadcasting the present one has decided to leave editorial ours? THEgineers recently closed and work and into manufacturing. And further a trader, even the most modest commentator go Sidney The managing editor, Mr. Willis K. Wing, after a trip to the United States, said: must declare it was an unexpected will succeed him, and the rest of the staff will success. Not only did the attend- remain the same, with Mr. B. Brennan as I went over there to admire American ance the that John justify opinion there but I came back with the technical editor, and Mr. Keith Henney as di' broadcasting is a host of capable engineers work- full conviction that taken all around our rector of the Laboratory. The policy of the ing in the radio field to-day, but the Australian broadcasting was better. magazine will continue along the lines set during fact that so many of them should More boost has been put into American Mr. Lynch's Professor Morecroft come distances at considerable editorship. broadcasting than into any other thing long will continue to write "The March of Radio" and it becomes natural for us to associate expense speaks well for the past and the other departments will be continued everything that is good in broadcasting year's prosperity in the radio busi- by the same writers. with the country whence that boost ness. Enthusiastic as radio workers DOUBLEDAY, PAGE fi COMPANY. emanates. . . . We blink at the be, without a may materially pros- fact that America ... is now up business behind them perous backing against a serious problem of extricating up their plans and ambitions, the the broadcasting situation from the

engineers could not have turned out in What the Australians Think of chaotic condition under which it labors. . . . the numbers they did. Their Broadcasting And then to make sure that we are down The Institute is not yet fifteen years old " for the count of ten if we must pattern but the membership already totals about [O POSITIVE methods of comparing ourselves after somebody else let it be after three thousand. Probably in no other foreign broadcasting with that in the the British system which, built up on a solid national engineering society is there such a N' United States exist, but it is always foundation, stands out as preeminent." preponderance of young men, and it is the to note what outsiders say. A. W. Watt, This is criticism indeed, from one of our most presence of young men in an association of editor of Wireless Weekly (New South respected neighbors. Are we really as good this kind that promises much for its future. Wales), writes: as we have been ourselves we are? The older societies with their venerable and telling The broadcasting in Australia is excellent. bemedalled members of the engineering This is the well-considered opinion of an official 'An Official Indiscretion" profession may well point with pride to the of one of the largest British wireless concerns. of these well-known NDER this caption, the editorial accomplishments fig- This opinion coming from one who has, if only but their work is in in the writer of the Wireless World takes ures, general from a business point of view, intensively studied It is in hands of u to task that admirable British en- past. the the younger the quality of British broadcasting which is and almost unrecognized members that conceded even by our cousins in America to gineer, Captain Eckersley, Assistant Con- the future of the profession lies. It was with some doubt that the Board of Direction of the Institute started their plans for this first con- vention but the out-come well justi- fies their judgment that it would be worth while. Such a call a decade ago would not have gathered more than a dozen men, but so great has been the recent demand and the resulting sup- ply for technical radio men that sev- eral hundred attended this meeting. The convention did not attempt the ambitious programs carried through by some of the other engineering bodies, yet there were some valuable papers presented and interesting and profitable trips were planned to the Bell Telephone Laboratories, to the high-powered station wjz at Bound Brook and to the factory of the A. H. Grebe Company operating sta- tion WAHG. The session closed with a most successful banquet and we must admit that never before had we believed that so many radio workers could attend a five-dollar dinner, but there were hundreds of them there to SOME OF THE LEADING MEMBERS OF THE INSTITUTE OF RADIO ENGINEERS testify to radio's prosperity. Jewett, the recent convention of that in New York. In the front row, reading Nally, Alexanderson, Langmuir, Fes- Photographed during organization left to right: Frank Conrad, assistant chief engineer of the Westinghouse Company, who received the 1925 senden, and other noted workers in ?500 award of the Institute for his work in short wave broadcasting; Donald McNichol, president of the the radio field brief talks, all of gave Institute; Dr. J. H. Dellinger, director of the radio laboratory, Bureau of Standards, and retiring president; them bringing out the tremendous Dr. A. N. Goldsmith, chief broadcast engineer, Radio Corporation of America; R. H. Marriott, first presi- dent of the second left to W. H. V. L. C. W. strides radio is sure to make in the Institute; row, right: Hubley; John Hogan; Home, manager of radio for the Westinghouse Company; Lloyd Espenschied; A. H. Grebe; Professor J. H. Morecroft of decade. (The modest writer coming Columbia University and member of the staff of RADIO BROADCAST; Melville Eastham, president of the these editorials was also of among General Radio Company; Dr. G. W. Pickard, research engineer, Wireless Specialty Apparatus Company; the speakers. Editor.) L. E. Whittemore, and Dr. E. F. W. Alexanderson of the General Electric Company 654 RADIO BROADCAST APRIL, 1926 trailer and Chief Engineer of the British vitamines of the radio industry. He really to think that circumstances were doing so Broadcasting Company. learns a lot about radio, he spends much well to keep us from being contaminated In an interview entitled "A Talk to money for parts; he spends his time at by touch, even over an ether channel, with Homemakers" he saw fit rather severely to home, contented and enthusiastic about our transatlantic fellow men. Rapidly criticize the enthusiast who buys parts and his task, he occasionally lets his family changing weather conditions, which always assembles them into the well-known home- actually listen to a whole selection from bring plenty of static, resulted in violent made set. Not only did he tell the radio some distant station before he tunes to Atlantic storms, and as soon as the static "tinker" that he was generally wasting his another, and in many instances he also had partially abated, the transocean chan- time and money but further intimated that buys a manufactured set. So actually in- nels were required for more important ser- the home builder was actually doing an stead of cheating the set manufacturer vice than that of friendly intercourse. Radio unethical thing: that he was using ideas from his legitimate profit he generally does was being used to locate the men who were which had cost the manufacturer thousands contribute his bit and in addition creates a fighting against death in the ocean storms, of pounds to develop and for which the healthy demand for "parts." and no one of us has ever begrudged giving manufacturer was entitled to believe that up his radio hours for such a cause. the radio listener would buy his sets and The Recent International Radio The law of compensation its part " played thus help pay for the cost of research. If Broadcast Tests in the ocean tragedy, however; one of the home making simply means copying what benefits of these International Tests which some one else has taken pains to design, year's international tests ran some of us had continually urged is that may I suggest that mental indigestion may THISinto difficulties with a vengeance. arising from the better understanding be- result, and more, might I point out that a It seems as though nature, as well as tween nations. This must result from our new and great industry is being ham- the bloopers, were making all efforts to repeated attempts, always more successful, pered"? keep America for Americans. It probably to get in radio touch with those in Europe The home builder is one of the important pleased many of our short-sighted senators and South America. When peoples are in

MARINE RADIO DIRECTION FINDERS Three nations have recently joined to honor the Captain and crew of the S. S. President Roosevelt on their rescue of the crew of the British steamer Antinoe. It was radio which brought the rescue ship and the radio compass which guided the Roosevelt to the drifting Anlinoe after the American ship had drifted more than 100 miles out of her course during the night. The large illustration on the right is the Kolster radio compass installed on the bridge of the S. S. President Harding, a sister ship of the Roosevelt. The wheel operates a loop above, which leads to the receiver at the right of the operator. The view at the left is the antenna of the British Bellini-Tosi direction finder, installed on the bridge of an English merchant ship. Its principle of operation is somewhat different from the Kolster system used on American vessels APRIL, 1926 THE INTERNATIONAL TESTS 655

close communication with each other, many Strange as it may seem to those in con- West Coast stations interfering with her sources of friction and causes of discord will trol of our governmental attitude, the eastern stations, Canada counts on 19 disappear. Now the time used for the Canadian government has a definite policy available channels. sos calls during the International Test by which broadcasting licenses are issued. Continues the report: schedule resulted in American crews and "One wavelength is issued to each city or Every Canadian station is checked each night German crews risking their lives for British area and three stations are licensed to use by some specified inspector and offending sta- crews, an international of it, one station at a time. In case the li- certainly episode tions are at once ordered back to their specified as much as the of the to importance exchange censees are unable arrive amicably at a wavelength. Should the offending station be for "Star-Spangled Banner" the strains of division of time, the department itself di- under the jurisdiction of the United States, the "God Save the King." vides the time on an equitable basis." This Supervisor of Radio for the area in which the This year's Tests further emphasized the is different from the Cincinnati row we had offending station is located is advised by tele- and in all cases and undesirable character of the regenerative when the Department of Commerce officials graph promptly effectively attends to the receiver in the hands of unskilled or careless said it was none of their business and left complaint. users. Much of the time when the air was the stations to fight it out. In the larger The report speaks of the surrender of the otherwise clear and the chances of having Canadian cities, a second wavelength is 1000- and 66o-kc. channels by the shipping European and South American radio chan- assigned but the station operating on the approaching our shores. They are not nels end in our homes, was rendered useless second wave must be at least ten miles used by ships of Great Britain, United to us by the howling receivers. As soon as out from the city! States, Belgium, Denmark, and Sweden we located one of the transatlantic channels For the past two years, licenses issued when within 250 miles of our shore. "Un- and were endeavoring to copy the program, by the Department have permitted indirect fortunately France has not seen her way a flock of howling receivers would start to advertising without restriction and direct to accede to our request and we still have work around, trying to locate the same advertising before 6 P. M. In spite of the a prolific source of interference in the station. It is high time that common de- permission, practically all direct advertis- coast station operated by that government cency to our neighbors prohibit the use of ing has been abandoned, the stations ap- at St. Pierre Island, south of Newfound- " such equipment and especially on such an parently having reached the same con- land." Under the caption Regenerative occasion as the long-distance tests. clusion that direct advertising fell on Whistles" we learn that "We have as a "deaf" receiving sets. matter of fact, considered getting all the How They Run Radio in Canada In 1923 the United States assigned to its Canadian radio manufacturers together numerous licensees all of the broadcast with a view to having them mutually agree CANADA the radio activities of the bands available for this continent, a not to stop the manufacture of the regenerative INgovernment are carried out in the De- very neighborly action. Ninety-five chan- type of apparatus. But as there is no partment of Marine and Fisheries, a nels to be properly proportioned between legislation available to compel any manu- " logical place for it when we remember that Canada and ourselves so we use all of them ! facturer to abide by the same, etc. radio served the marine service long before "As a result, the transmission of practically With comparatively few broadcasting it was used for broadcasting entertainment. every one of our stations was subject to stations (only nineteen channels), Canada We have commented before on what seemed severe interference." The United States has thirty-eight inspectors. "Generally to us the very reasonable and sane course Department of Commerce finally agreed to speaking," the Commissioner modestly the Canadian officials take in developing regard six of the ninety-five channels as concludes, "the Canadian broadcast lis- radio in fact, we have also previously ex- exclusively Canadian and also to use cer- tener would appear to receive at least as pressed the opinion that the work was done tain of the other channels for our southern much, if not more, service than the lis- in a manner somewhat superior to that stations only, that is, these channels might teners in any other part of the world, which our officials display in attacking also be used by our northern neighbor. whether licensed or not, and we have not radio questions. It is good to find the Taking into account the unlikelihood of as yet really got into our stride!" quality of directness of attack for which the Canadians won a reputation during the war, shown in the annual report of the Canadian radio service. The totai number of stations coming under government supervision is 93,049, apparently a prodigious number, but we hasten to recall that all receiving sets are classed there as receiving stations and come under government supervision. There are 92,000 of these receiving stations in the dominion which pay to the government $1.00 a year for their operation. After re- viewing the compass service and the twice daily weather report to shipping, the prob- able development of radiophone service to certain classes of shipping is discussed. The ordinary weather and compass reports are of course sent out in code and the re- ceiving ship must have a trained operator on board. But it is thought that harbor shipping might use radiophone channels and thus get the benefit of radio without the expense of a specially trained man. so as A of 1 500 kc. is to be used frequency RADIO OF THE SIGNAL CORPS not to interfere with broadcast channels. HEADQUARTERS At all the official business of the of the which is transacted radio It seems to us that such a scheme is only Washington, Signal Corps Army by through the network of Army stations is received at this central office. General Saltzman, Chief when the shipping is not dense. practical Signal Officer, reported recently that radio was the means of saving a large sum over the usual tele- such an Around New York harbor, attempt graph tolls paid by the Army for official communication. This radio central is located twenty feet would be unwise indeed. below large receiving loops on the roof of the building 656 RADIO BROADCAST APRIL, 1926

service and certainly cannot be based on the idea of earning a reasonable return on the in- vestment.

more indicative of the emancipa- NOTHINGtion which Turkish women have experi- enced in the last decade has occurred than the broadcasting of a speech by the wife of the Curator of the Evkaf Museum in Constanti- nople. Only a few years ago the face of the Turkish women could be seen by her master only, and never could she talk to other men. Now she not only shows her face as other women do but addresses an audience numbered in the hundreds of thousands by the most modern of our scientific achievements. Mme. Aly ad- dressed the British radio audience on "The Turkish lady of Yesterday and To-day." The topic certainly seems to offer opportunities for some striking contrasts. REGINALD A. FESSENDEN

the radio had a chance Chestnut Hill, Massachusetts wov, audience FROMto listen to a most ex- at the Institute of Radio Engineers recently striking Dinner, New York periment. Professor Wold of Union College, gave a series of talks on the electron and its " CAPT. A. G. D. WEST There are in existence to-day, fully de- activities and during one of his lectures he let his wireless methods veloped and tested, for listeners actually hear an electron as it splashed London; Assistant Chief Engineer , operating substantially without disturbance its a cloud of Some way through gas particles. British Broadcasting Company; in an static or and these means said to be are con- from interference, substances, radio-active, interview before the recent have been tested with high off large capacity tinually shooting positive and negative International Tests in antennas between Boston and Panama, electrons, and as these, traveling at high speed, " summer. their a small air chamber and The tests will not such a " bump way through give unique There are also in existence to-day, fully so affect the air particles they bump that the opportunity to European listeners because tested in all essential developed and details, air becomes partially conducting. This change they can listen on any night to American wireless methods without for operating direct, in the conductivity of the air is made to affect stations withmit fear of interruption from subscribers' exchanges, by setting direct to the a vacuum tube amplifier and thus modulate broadcasting stations on this side of the as numbers, between bodies of subscribers the carrier wave of the broadcast station. Atlantic. American stations usually take ex- large as those comprising the New York The noise is scarcely more pleasing than static very great care with regard to maintaining changes. noise, but it will be more their and their constant " certainly interesting wavelengths power been de- The wireless pheroscope has when one realizes that each noise represents the over long periods of time, so that amateurs on veloped from the first crude apparatus of collisions caused by one electron, the smallest this side who want to do serious experimental 1906 to a device capable of putting wireless thing in the universe of which the scientist work on long distance reception on various vision into every house in the United States, knows to-day. wavelengths, can do so throughout the winter and was tendered to the United States Navy season, but there are not many experimenters under guarantee in 1921, and to others. who would have time and opportunity and inventions Its success depends upon tu.o also inclination to listen in the early hours the valued as it is multiple function method, night after night for American stations to called, and the shutter which has been opera- Interesting Things obtain data that will be valuable from a ted at a and it is by independent engineers frequency Said Interestingly scientific point of view, during of 400,000 per second and is capable of Radio Week that a more useful opportunity the more. I have pleasure in showing you is given to those who want to try occasional shutter, a photograph showing its general American reception. c. HARBORD " in action, and a sample the j. (New York; Even now it is not advisable listeners arrangement of -* for it president Radio of America): wire used, of which takes goo twisted to- Corporation with sets containing less than two valves to and "The world leadership of the United States in the gether to make the si^e of a single hair; attempt to pick up these (American) pro- historical exhibits to the development of the radio art and industry has of presenting these grams, and it is certainly most important won for our manufacturers and a archives of the Radio Engineers." engineers to make sure that the sets do not oscillate and dominant position in the radio affairs of South cause local interference. Even just a few America, where the to-day greater percentage oscillators playing around the wavelength of of the total business is carried on Americans. by a distant station can completely spoil the In spite of foreign competition, our products reception of that station by listeners situated and methods remain the most acceptable to many miles around." The Month In Radio South Americans. Our four years of experience in the development and production of broad- casting devices both for transmission and re- has stood us in stead in Latin ception, good to minimize interference; and the use of long America. Americans are a full large station at Rocky Point (Radio contributing waves to minimize fading. The future answer measure of this toward the THECentral) has for some time been able to send experience develop- to these problems may be different. At least ment of radio in South America and we have the telephone messages across the Atlantic to Eng- we have reason to think that the new knowledge of local South American land where a receiving station has been set up hearty cooperation which we have gained regarding wave propaga- radio interests." at Chedzoy; this, it is expected, will be the Eng- tion will furnish us additional methods of dis- lish receiving station for the transatlantic radio- criminating between signals and disturbances. phone channel. The British have been at work F. W. ALEXANDERSON (Schenectady; Wave polarization will undoubtedly be one of on a transmitting station for their end of the E. Chief Consulting Engineer, Radio Corpora- the important factors in this new development." channel and a cable to the New York Times says tion of America): "The great problems in radio that the station is now complete and has been are static, interference and fading. The trend A. M. LOW (London; from an article PROF. " taken oxer by the British Postoffice, which will of the radio art in the past has been determined in John Bull) : Before many years are operate the communication scheme. by improvements that have been made in over- passed we are sure to have the radio serial story, The English news puts the price of a three- coming these difficulties. The practical solu- and we are sure to have plays acted by radio with minute talk to America at five dollars. This tions of these problems to-day are; directive re- various incidents leading up to exciting passages seems like an unreasonably low price for the ception for reduction of static; continuous waves which are always 'to be continued in our next.'" News of the $500 Short-Wave Receiver Prize Contest

Entries May Be Made Up to April 1, 1926, Instead of March 1 Conditions and Further In/ormation of a Contest to Interest Amateurs Everywhere

short-wave set receiving con- Performance 25 That public interest and attention is announcement of which Overall of test, was amplification signals turning toward short waves is no longer a in the Use in relaying made February issue of debatable question. The announcement Ability to use break-in THERADIO BROADCAST, has won the of this the contest, RADIO BROADCAST- Ability to cover foreign amateur bands enthusiastic response of numerous experi- Eveready short-wave experiments con- Appearance 15 menters in the short-wave field, judging ducted with the of the National Method of avoiding radiation .... 10 cooperation from the which has in correspondence come Carbon Company, the long-distance records since the announcement was made. So 2 Total .... 100 of GY have, individually and collectively, many complaints were received that there aroused so much attention that we are in- was not sufficient for of ex- Much comment has resulted in- time some the from our clined to predict that the number of enthusi- perimenters to finish their sets for sub- sistence on the non-radiating feature. Cer- asts in short-wave transmission and re- we are mission before the contest closes, that it tainly aware that there are differ- ception will continue to increase with the decided to extend ences between has been the time limit continuous wave reception marked rapidity of the last few months for from March i st to i st, A and broadcast The April 1926. reception. enjoyment some time yet. After all, your receiver the New York of of a broadcast entertainment can be com- request by representative may respond to signals coming in for ruined a Popular Wireless, London, that the receivers pletely by near-by radiating receiver distances of thousands of miles, but until of entrants from not but continuous wave is not neces- shipped Europe later reception you, yourself, have mastered the ether by than ist should be within of a radiat- April considered, has sarily impossible range making it subservient to the will of your been It is that the ex- receiver. Continuous wave granted. probable ing reception own transmitter, your conquest is not tension date will also enable is not the to however. Australian only thing consider, complete. It is our hope that through short-wave enthusiasts to compete. Short waves are also used for rebroadcast- the disclosure of a better short-wave re- and for One of the interesting things which the ing purposes supplying programs ceiver, RADIO BROADCAST may be the contest has forward is the to stations from remote brought fact broadcasting means of introducing you to a new phase of this A few hundred that up to time there has been little points. radiating receivers radio entertainment the mastery of the on short used for or no novelty in the design and construc- wavelengths, rebroadcast- ether through the use of the short waves. tion of short-wave receivers. The con- ing purposes, would be sufficient to make THE CONTEST ventional types have given satisfactory these short wave radio telephone links results and consequently, prior to this practically inoperative. In anticipation of OBJECT: The object of this contest is to contest, the stimulation to designing better this problem, RADIO BROADCAST adheres to aid in the development of improved short- receivers has been lacking. its fixed policy to discourage the use of radi- wave receiving apparatus, so that the According to present indications, among ating receivers on any and all wavelengths. possibilities of high frequencies may be the contenders for the prize money will be We have been invited to exhibit receivers more effectively studied. entered in the super-heterodynes, regenerative neutro- short-wave contest at the PRIZES: First prize, $250; Second prize, Sixth dynes and even the much neglected super- Annual Radio Show and Convention $150; Third prize, $100. Only one prize regenerative receiver. Certainly some- held at New York under the management of to a contestant. thing worth while should be brought the Executive Radio Council of the Second ELIGIBILITY: Anyone interested in short- District. If a forward. In practice, however, Reinartz sufficiently interesting ex- wave reception is eligible to compete, receivers are being used almost to the hibit can be assembled so early in the con- though no prizes will be given to manu- exclusion of other types. Attention is test, there will be an opportunity to see facturers making short-wave receivers or called again to the basis of points upon some of the latest designs in the short-wave parts therefor. which the prize is to be awarded. Con- art. CONDITIONS: Each contestant must sub- testants should observe that a paramount We have sought to make the board mit a complete description, photographs, requirement is that the receiver shall be of judges a composite one, which will be and hook-up of a short- wave receiver which adapted by its design and construction to thoroughly capable in considering all of does not radiate. The receiver should be practical amateur relaying. The only the qualities of a receiver. You will adapted to the entire short-wave band observe that it circuit limitation imposed is that radiation includes practical ama- from 8566 to 1999 kc, although this may be reduced to a minimum. Otherwise, any teurs, who have extensive experience in be accomplished by interchangeable coils. type of receiver which will function with short wave relay work; scientists and RADIO BROADCAST is permitted to request the utmost sensitiveness, stability, and mathematicians, who know how to meas- that the most promising receivers be sent ure in reliability, is eligible for consideration. and appraise impersonal quantitative to its laboratories, in order that the final The extension of the contest, which has terms, and writers and commercial engi- award of the prize may be determined, been widely announced, will give contes- neers who are able to judge the simplicity of after exhaustive tests. In addition to tants opportunity to do additional work, workmanship and ease of construction from the prizes, RADIO BROADCAST is to be per- which should not be overlooked. the point of view of the average home mitted to use descriptive matter, either in The basis of points is as follows: constructor. There are many names which whole or in part, submitted by any con- we would have liked to include in the testant, at its regular rates. Workmanship 15 Board who were perforce omitted, lest it BOARD OF JUDGES: The following consti- Simplicity of handling 20 become too large to be efficient in its work, tute the board of Ease of Calibration judges: Boyd Phelps, but we are sure that each member has a Prof. Louis A. Hazeltine, Zeh Bouck, G. C. Freedom from hand capacity and definite contribution to make Arthur H. H. Independence of tuning and regeneration specific Furness, Lynch, Edgar Felix, Low Cost 10 which should result in a fair decision from Dr. Lawrence Dunn, and Dr. A. Hoyt Use of standard or easily constructed parts 5 every standpoint. Taylor. The Tube and Its Best Uses

Explanations of Some Qeneral Instructions on How Best to Use Tubes How Characteristics are Measured and Their Importance Relative Merits of Amplifier Connections The Facts About Tube Rejuvenation By KEITH HENNEY 'Director, Radio ''Broadcast Laboratory

in have ADIO receivers arrive American requested tube data from RADIO BROAD- the oxide coated filament type plate voltages homes at the present time in one of CAST Laboratory wants to know how to meas- up to 400 have been used in the Laboratory with two ways, either the home buys a ure tubes in the most approved fashion. The complete success. The C voltage on these tubes

receiver or someone in the article be of interest to both of of the 1 completed present may 12 type may be varied in steps of 5 volts builds material that some these of readers. home it, assembling types from minus 35 to plus 5. manufacturer has designed and constructed. With regard to static and dynamic character- Now it is a common statement in published In either receiver is static is this to said difference case, the a thing istics, there be a does tube information that only the straight com- until listener the tubes and turns on exist between both are neither the buys them; important; paratively speaking part of this grid-voltage- the A battery. From the moment that this is difficult to measure. And it is doubtful if the plate-current-curve should be used for distor- tube tester final act is completed, the receiver ceases to be dynamic mentioned before has any- tionless amplification. Any one can see that the to do with the so-called a mere assembly of electrical apparatus and thing dynamic character- curve is not straight at the bottom, and on page becomes, for the time being at least, a stage upon istics of vacuum tubes. 458 of the February RADIO BROADCAST, the effect which many interesting things happen. of using this part of the curve is shown. But WHAT IS NEEDED TO TELL TUBE CHARACTERISTICS Few builders, or purchasers, of radio receivers any one can see that the curve continues to be seem to realize that the tube is about the from the tube and its bat- only ASIDE accessory straight beyond the zero grid line. In other part of the complete installation over which they teries, all that is necessary to measure static words, there seems to be no reason why the set comes have any control. The purchased characteristics of tubes, which show in the form grid should not be allowed to go positive. There "without tubes" and the final contribution to of curves the relations between grid, plate, and must be a catch somewhere. the home made receiver must be tubes. These filament voltages and the corresponding cur- The catch lies in the fact that the method of tubes must be chosen with considerable discre- rents, is a good voltmeter of double range, o-io discovering the relation between Ip and Eg tion and operated with care. and o-ioo volts, and a good milliammeter, and (plate current and grid voltage) illustrated above It is sufficient for the average listener if his any one in his home laboratory can have many does not tell us exactly what the tube will do set works, and under this happy condition a hours of enjoyment studying tubes by means of under actual amplifying conditions. For in- fits into a tube is a tube, an ingenius device that these instruments. With such apparatus dia- stance, an amplifier tube always works into a a socket. Yet let something happen, mix-up grammatically represented in Fig. I, let us carry load of some kind; as the telephone engineers in B a a out the A and battery leads, broken connection, following procedure: say, the tube "looks" into a transformer, a re- without de- dropped tube, and the user realizes sistance, or 'a pair of telephones, and the grid is vital and that a. Measure the B lay that the tube the thing, battery voltage. circuit, in the same language "looks back into" b. Set the filament at upon its proper functioning depends the success proper voltage. a transformer secondary, a resistance, or some c. C in convenient meas- of the receiver. Vary voltage steps, combination of resistance, inductance and ca- uring with voltmeter. For this reason this article, with those pub- d. Note plate current at each different C pacity. lished in the December and February RADIO if we insert into the and voltage. Therefore, grid plate BROADCAST, endeavors to some tube in- a resistance explain e. Plot the results similar to Fig. 2. circuits of the tube under test, ap- formation tube Such and some idiosyncrasies. proximating the impedance into which the tube in the words of a certain information, college For 199 and 2OI-A tubes, the normal plate normally looks we shall have the conditions of "is in all the books" but that professor many voltages are 45, 90, and 135. The C voltage may test more nearly like those occurring in practice.

should have noted it, have not. To from i these addi- judge be varied in steps of 2 volts from minus 10 to Fig. 3 contrasted with Fig. shows the enthusiastic the first two reception given plus 10. Semi-power tubes normally use 135 tions, and Fig. 4 the method of calculating the tube this field is a one for articles, profitable volts on the plate but as many as 180 may be input and output resistance. The tube normally study. safely used. On some tubes of this type not of looks back into the output impedance of a similar other about tubes that are fre- Among things tube which is "stepped up" by the square of the mentioned in radio and news- quently magazines turn ratio of the connecting transformer. Fig. 5 radio sections is the fact that an paper amplifier shows how two differing impedances may be should never be allowed to and grid go positive, coupled together by means of a transformer. In this seems a of attack for the logical point present this case Zi may be the output impedance of a article. of a loud semi-power tube and 7. t the impedance It is also stated that the characteristics of tubes speaker. If the turn ratio of the transformer as measured are "static" and have ordinarily obeys the formula little to do with the tube under actual operating conditions. At least one manufacturer of tube testers claims that his device measures the or "dynamic" characteristics of tubes giving the lie to others whose products measure tubes statically. This particularly efficient instru- ment, so the manufacturer says, measures tubes the maximum amount of power will be trans- dynamically because it uses a source of alternat- ferred; in other words, quality reproduction will ing current for the measurements, and everyone result. knows that tubes are alternating current ampli- E P =EB In connection with this formula it is well to fiers. remember that the on And there you are! L Efc.Ep-.->| voltages appearing prim- Naturally, what the average listener wants is ary and secondary of transformers vary di- information that will aid in his as the turn ratio, while the him operating FIG. I rectly impedances the tubes intelligently; it matters little to him by which the transformer connects vary as Apparatus required for measuring static charac- what name call tube or how of the turn ratio. you characteristics, teristics of tubes. A double-range voltmeter square In the case of a first they are measured. He wants the "cold dope." can be used to measure A, B, and C battery stage amplifier working will be And the experimenter how many there are who voltages from a detector tube whose impedance APRIL, 1926 TUBES AND THEIR USES 659 about 30,000 ohms and coupled to it by means plate voltage is less than the B TABLE 1 of a 3:1 ratio transformer, the tube looks back battery voltage by the drop in into = approximately 30,000 x (3)" or 30,000 x o, the load impedance. The plate 270,000 ohms. If the tube is the second of a current will be less naturally. two- or three-stage resistance amplifier employ- When the grid goes positive it ing high-mu tubes, the tube looks back into three begins to draw current so that in as impedances parallel shown in Fig. 4. In variations in grid voltage are no the case of the last tube in a set which works into longer as effective in changing the loud speaker, its output impedance will be plate current; then these varia- approximately matched by the impedance of the tions only produce more or less grid current. In a poten- tiometer-con- trolled radio frequency

1 i fi e r a m p , very heavy- plate currents are drawn To Preceeding , To Following when the grid Tube Tube is forced posi- tive by stabi- lizing adjust- ments. This is due to 660 RADIO BROADCAST APRIL, 1926

RESISTANCE AMPLIFIER Rp(Hi-mu) = 60,000 Ohms

DETECTOR AMPLIFIER = Rp (Detector) 30,000 Ohms Rp (Amplifier) = 15,000 Ohms 2 2 Ri - 3 xRp =270.000 " Ri=4 x 15,000 = 240.000 Ohms

FIG. 4 Methods of calculating Ri and Rp for three general amplifier cases direction there is an analogy rouge blindness! means in relation to proper tube operation. abbreviated to read Cm and defined as the

The more rouge, the more . . . but per- Tubes are most frequently called upon to per- amplification constant divided by the plate haps we had better not go into that. form one of two functions, voltage and power impedance. So much for distortion owing to positive grids. amplification. It is important then to know The same mathematics, however, shows that Too much C battery, however, will force signals how useful a given tube will be when used as a these functions are related in the following to use too much of the lower part of the charac- manner: teristics and will cause distortion. A load in the Np Ns = -t Voltage Amplification j \/Ri X , plate circuit, however, has the tendency to V Rp out the straighten Ip-Eg (plate current-grid = ' Power Amplification X 73 voltage) curve, so that the bottom of the curve 2 Kp 2 is not so bad as it looks from the static character- Eif* u. Power Output = -p X istics. Kp

Consideration of the curves in and those ti. Fig. <> = Mutual Conductance 77- in Popular Radio already mentioned show that RP the greater the impedance in the plate circuit 0- the will be the characteristic. Some straighter The mutual conductance, then, is a measure loud have little at low speakers very impedance of a tube considered without regard to the circuit so that the curve worked over is not frequencies in which it works, while the other facts outlined but curved and a distortion re- straight peculiar above depend upon these external conditions. sults when bass viols, or kettle drums are played. F'or example, the values in Table are for The remedy lies in a lower impedance tube, say Kp one of 4000 ohms, and some tube manufacturers and , and the as are to such tubes. knowing input impedance making preparations supply y RP They will necessarily have a low amplification figured in Fig. 4 and the voltage that is being factor and will draw considerable plate current Np=Primary Turns placed on the grid of an amplifier, it is a simple but will be capable of delivering considerable Ns-Secondary Turns matter to compute the power and voltage am- transformers useful in overcom- power. Output plification and the actual power output in watts this of distortion are manufactured FIG. ing type by

M- 5

SINGLE TUBE PARALLEL TUBES PUSH PULL

FIG. 6

Methods of calculating the important factors of three commonly used amplifier connections. One point worth noting is the fact that the push-pull input coil divides the voltage so that the effective step-up to each grid is only one half the total turn ratio of the transformer. In the push-pull circuit, the two tube irrpedances are in series: in the parallel case they are cut in half APRIL, 1926 TUBES AND THEIR BEST USES 661

THE MERITS OF VARIOUS AMPLIFIER CONNECTIONS The Electrical "Shorthand" Terms Used in with these facts in mind let us settle a NOWfew arguments about the relative merits of a single tube compared with a push-pull amplifier or with two tubes in parallel, each working into a loud speaker designed to match approximately the output impedance of the amplifier. In Fig. 6 these three amplifiers are shown and the values ! of rr, voltage amplification, and power output

given. The factor j which is included in the above expressions for voltage and power ampli- fication has not been used in these computations since in these cases a high impedance open cir- cuit secondary is used. It will be noted that the push-pull and parallel tube amplifier will deliver twice as much power to a loud speaker as a single tube with the same input voltage, but that the push-pull amplifier is behind the others when it comes to voltage amplification. Now, in any amplifier, the tubes, with the exception of the last one, are primarily acting as volt- age amplifiers, boosting the voltage as much as possible without distortion so that the last tube whose power output

(input v ' tage " *>* is expressed as oKp gets as much voltage input as pos- sible. The push-pull amplifier should be used to feed power into the loud speaker, and practically any tube can be used up to that point, that is a 199, 12, or2oi-A. These preliminary tubes are not required to handle much power since they are functioning primarily as voltage multipliers. 662 RADIO BROADCAST APRIL, 1926

sight of the fact that the ear is a de- TABLE 3 ceptive measuring instrument. It hears according to a logarithmic scale, that is, a signal with one hundred times the power of another signal will sound only twice as loud. For that reason, the difference between a 3:1 and a 4:1 transformer in an audio amplifier is scarcely noticeable. For example, the parallel tube amplifier compared to a single tube has 1.4 times the voltage amplification and twice the power output. This difference in logarithmic "transmission" units is only three units, and it takes a trained ear to detect such small differences. For the same reason the fact that it is not possible to "match" a loud speaker to a tube at every frequency in the useful audio range should not worry a listener too much. Any one can tell the difference between a terrible loud speaker of ante-quality days and a fine one, or with the latter the differ- ence between running it from a 199 tube and a 1 12, but in general any one should be satisfied with an amplifier that uses two of the modern high grade transformers, or a resistance or impedance amplifier properly constructed and operated, with a semi-power tube in the last stage and] proper B and C batteries, especially if this amplifier delivers its output to a cone type speaker that is properly made. At this point it seems fair to point out that a speaker that merely uses a paper cone is not necessarily better than a speaker of the horn type. Much depends upon the element that drives the cone and upon the methods of con- struction and mounting. The only test is to listen to it compared with other speakers in which the listener is interested. Comparisons should be made both as regards fidelity (quality) and efficiency (volume with a given input). Some cones are remarkably inefficient. HOW NOT TO CONTROL VOLUME

IS weli too, to point out the fallacy of con- IT trolling volume by regulating the filament voltage of audio frequency amplifiers. As soon as the voltage is reduced to the point where volume is reduced, the impedance of the tube is increased, resulting in the dropping out of the low notes. If the low notes seem to have been lost, or the amplifier has a tendency to howl, charge the battery. Much distortion can be laid to a detector or amplifier filament that is run at too low a voltage. Reduced emission due to too low filament voltage results in distortion due to the inability of the plate current to follow the peak input voltages. Low B battery voltages also result in poor quality due to increased plate impedances. APRIL, 1926 TUBES AND THEIR BEST USES 663

at least 9 volts variation on its 80 process. Tubes can often be re- grid. A tube with a mu of 8 vived by burning the filament for means of resistance or several hours without the B coupled by 70 battery. impedance to the amplifier can- WHAT "IMPEDANCE" MEANS not produce a variation of vol- than 8 volts and 60 tage greater V) the many readers to whom probably not over 6, so that the U FOR cc PERIKON CRYSTAL the term "impedance" is some- amplifier will not deliver its rated 50 thing of a mystery, the following of power. On the other quota explanation may be of aid it is hand a tube with a mu of 20, or a o not intended for engineers. In tube with a mu of CC. 5 coupled by o 40 direct current circuits vacuum means of a 2:1 transformer, can tube filament circuits, for exam- easily produce the desired change o 30 ple the resistance controls the in mu tubes input voltage. High ci flow of current. In alternating can be used as detectors and hence Q current circuits, for example, the are useful in vacuum tube volt- g 20 plate circuit of a tube in which meters. Their use in resistance there is an inductance coil, an and impedance amplifiers makes 10 additional factor comes into play. the latter without in- practical There is resistance and induc- the B creasing battery voltage tance, both of which tend to limit reason. It be said beyond must the flow of current. These two here that the mu of such tubes is factors may be combined into a not the only important constant. single term called impedance. If The must be con- 10 plate impedance there is no inductance or capacity sidered and, like all other tubes, in an a.c. circuit, the impedance the usefulness of tubes high-mu 20 is the same as the resistance; if increases as their de- + .1 .2 .3 impedance .1 -0 these other factors appear in the creases. the resistance must be (Ej) A.C. VOLTS circuit, combined with them to calculate REJUVENATING TUBES FIG. 8 the impedance. are many rejuvenat- This curve shows that the crystal detector follows a complicated The impedance between the THEREing devices on the market at curve not a straight line differing but little from the grid filament and plate of a vacuum current or current curve of a the present time. These cannot voltage-plate grid voltage-grid tube is practically pure resistance, vacuum tube. The increase in when a be used with any tubes except apparent quality using and its d.c. plate circuit resistance crystal detector is probably due to lack of tube noise introduced those which have thoriated fila- may be figured knowing the plate by a grid condenser-grid leak detector ments. They will be of no ser- voltage and the plate current. vice with the old tungsten filament As an example: If the plate 201 or 200 type tubes, or with the new ux-i 12, or before and after the process. Fig. 9 shows sev- voltage is 90 and the plate current 6 milliam- with Western Electric tubes. On the other hand eral tube flashers that have been tested in the peres, the d.c. resistance is 1 5,000 ohms. The they are very efficient when worked with thor- Laboratory. It will be seen that some tubes impedance of the tube, however, as measured on iated filaments of the 199, 2OI-A, 120, 210 and went dead in the flashing process while many an alternating current meter differs from this used in certain 1 12 type tubes. The data in Table 3 gave increased plate current. At any rate the value, and since tubes are alternating gives the result of recent rejuvenating in the user has everything to gain, nothing to lose in current circuits it is not correct to use the above Laboratory showing the plate current in milli- the process. If his vacuum tube is no good be- figure when calculating the amplification, etc., as amperes at 90 volts on the plate and zero grid fore, it cannot be worse after the rejuvenating has been done in this article.

FIG. 9 A few of the tube rejuvenators now on the market. Those illustrated here are the Jefferson, the Sterling, the Burton and Rogers and the "Socket" tube reviver. The device with two meters is to measure the plate current of a tube so that one can tell if the reviving process had any effect. Another re- juvenator which is not shown here but which has been used in the Laboratory is the Hemco The "ARISTOCRAT"

Some Variations of this Popular Quality Circuit which Originally Was Described in the November, 1925, "Radio Broadcast" RADIO BROADCAST Photograph the of WHERE TWO CONDENSERS ARE EMPLOYED Application Dual-Control Tuning To tune the RADIO BROADCAST "Aristocrat," a very symmetrical layout may be had. In the receiver illustrated here, Silver straight line frequency condensers have been used. The panel size is 7 x 18 inches

RADIO BROADCAST Photograph UNDER THE SUB-BASE

Showing most of the wiring and the method of mounting of Daven resisto-couplers and Amperite filament control. Moulded hard rubber brackets have been used to hold the panel and sub-panel together, and to act as rests for the completed receiver. This receiver and other models of the "Aristocrat" were designed by Arthur Lynch

A TOP VIEW OF THE TWO-CONTROL "ARISTOCRAT"

The layout, on an ordinary baseboard, and simplicity of wiring, make for compactness without stray capacities or the necessity of shielding. In this receiver the single General Radio 20-ohm rheostat is in the filament circuit of the r.f. tube. Daven j-ampere ballasts are used in all the other filament circuits save the extreme right, where the size of ballast depends on the output tube used. The plate voltage arrangement found best with this receiver was 90 on the r.f. and a 4.5 negative bias; 45 on the detector, and 135 on all three audio stages with 4.5 bias on the first two and between 9 and 11 volts on the last. The parts employed in this model are Formica panel, Kurz-Kasch dials, Silver SLF condensers and Knockout coils, Daven ballasts, fixed resistors, and resisto-couplers, Silver ux tube sockets, Tobe-Deutschmann bypass condenser X-L neutralizing condenser, Eby binding posts, Sangamo condensers, Carter switch, and Pacent jacks ANOTHER TWIN-CONTROL "ARISTOCRAT" In this model the layout is altered somewhat by the use of a sub-base. This receiver is identical to the original RADIO BROADCAST "Aristocrat" for which working drawings in blueprint form are available. Amsco vernier dials, whether black, silver, or gold, show up nicely on the Insuline panel. The other knobs, left to right, are Carter antenna switch, Royalty r.f. rheostat, Hammarlund neutralizing con- denser, and Eastern tickler control

RADIO BROADCAST Photograph

A REAR VIEW OF THE SUB-BASE RECEIVER

Furnishing a general idea of the complete assembly. The tubes, left to right, are Cleartron cx-201-A Detector; two Cleartron Hi-Constron CT-101-A high-mu amplifier tubes; ux-112 Radiotron power tube; and ux-201-A radio-frequency amplifier. In this layout the resisto-couplers are hung below the sub-base rather than mounted on it as shown in some of the original models

RADIO BROADCAST Photograph A BEHIND-THE-PANEL VIEW

Of the set shown above, the layout above the sub-base, and the freedom from visible wiring this form of construction makes possible, is distinctly shown. The use of the Cardwell SLF condensers and Eastern Coils, resulted in both dials reading the same for any given station throughout the broadcast rar.ge.. Benjamin cushioned sockets for ux-base tubes were found very satisfactory. In this receiver Dubilier fixed condensers were used of Herbert Hoover's on this is I EGRETARY Commerce, letter, reproduced page, quite self-explanatory. There are without question, many radio receivers in working condition which are idle, and which would be of inestimable service to the lighthouse keepers at their lonely posts. We believe that readers of RADIO BROADCAST, if they know the service they can render by the donation of good receiv- ing sets, will not be slow in rendering the aid they can so easily offer. Readers of this magazine who have multi-tube sets which they are willing to donate to the lighthouse keepers, should pack them carefully and ship them to the Commis- sioner of Lighthouses, Washington, D. C., together with an explanatory letter to that official, who will see that the set is delivered to a keeper who could best use it. It is well to keep in mind the fact that the set should be capable of long distance reception, for as every marine traveler knows, lighthouses are neces- sarily located at lonely and

i often far COMMERCE \y out-of-the-way spots, from any broadcasting station. There are few more worthy causes than this, which RADIO s?. l January \ BROADCAST is glad to present, and we are sure that our read- ers, who best know the pleas- ure that a broadcast receiver can will not be slow in - bring, Garden ci* j j showing their generosity. to Dear

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LEAVING A LIGHTHOUSE Heavy weather often makes relief for the keeper g^l^^HS^^f;^;, and There are i / "**\f 4 uncertain infrequent. many radio lonely marine outposts such as this where would bring much comfort and pleasure. The radio receiver would be a gift of a sensitive welcome one indeed

HB- Conducted by John Wallace

Radio and the Taste of the Nation

Comes now radio, stalking in like the prover- There now, doesn't that give you a delightful icano cries out, "see how they appreciate mu- bial last straw, to put on the complete kibosh the glow; doesn't that tickle your superiority com- sic. It is born in them. It is part of them!" few straggling remnants of good taste that have plex; doesn't that neatly, though not too We are urged to ascend to the garlic saturated managed to linger on in this Land of the Cretin obviously, set you aside as one of the chosen few heights of the galleries of our local opera houses, and Home of the Depraved. who appreciate the bettah things; doesn't it and find there the Latins, the true appreciators of words taken from the utterances of any one give you a cosmopolitan and world traveled air? operatic music. And we find them there. But of several of God's private secretaries, expressed That at any rate is our explanation of the when? When the silly melodramas of Guiseppe editorially in any one of several pastel colored national delusion that the taste of the average Verdi or Donezetti are being yawped forth from periodicals on the occasion of that sage's dis- American is inferior to the taste of the average the stage beneath. covery of the existence of radio. Anything-else. The tired business man of Milan goes out in At risk of appearing to make ourself out to be the evening to have his spirit refreshed by some text of most of this pious pessimism is very widely traveled, we assert that this theory cafe or street corner band doling out dolorous that the taste of the American nation is is pure and undiluted bunk. The "man in the and sentimental tunes garnered from the jam THElower than that of any other similar body street" in Naples or Shanghai or Buenos Aires pots of the "classics." The tired business man of men on this sphere, and that, among the or Berlin or Paris is every bit as much of a dumb- in Pittsburgh takes his musical stimulus in the agents engaged in undermining it, radio promises bell as "the man in the street" in Janesville, form of a program of jazz. And we are inclined to be one of the most effective. Wisconsin. In fact if any difference in their to attribute a superior discrimination to the Nor is the custom of unfavorably comparing stupidity exists we should be inclined to give Pittsburgher. His taste savours less of the the kuliur of America to that of any other the American an edge more of appreciation. maudlin and more of the virile and lusty. nation confined to the so-called intelligentsia. Paris the cultural capital of the world! We are told that the European instinctively The habit is so widespread as to constitute There is more inferior and ridiculous statuary knows a good picture when he sees it, and at the almost a Dulcyism. That America, in respect lining the boulevards of Paris for the delectation same time we find on the walls of his home, even to its appreciation of the "higher things" is an of the Parisian "man in the street" than could as we do in Texas, color prints of "Aurora" or of be in a miles of infant among nations is, in fact, one of the ever found thousand our Main one of Carlo Dolci's sickly saints. cardinal planks in the American credo. It Streets. But it is the man in the streets of ancient the the self is finds place in our code of national convictions "Ah, but Italians," abasing Amer- Athens who most frequently held up to our along side of such sacred gaze as the supreme example tenets as "We must avoid all of the artistic cultivation of entangling alliances," "The the masses. And without French do not know how to pausing to examine any of the make coffee," "Success is numerous reference books on always the reward of effort," the golden age of Greece, we "Newspaper men are con- venture to guess that though scienceless scoundrels." civic art at that time reached "Abraham Lincoln was the a perfection never to be ap- incarnation of all virtue," and proached it was no doing of "The Japs are a dangerous hoi polloi. The politicians of little people." the time happened to be It seems unfathomable on gentlemen of artistic leanings, the face of it that this nation so they put up public build- of 100 per cent, boosters ings that seemed to them should be so clamorously in- good and they were good. sistent upon deprecating the The bourgeois Athenian ac- aesthetic consciousness of its cepted these exquisite edifices citizenry. But it needs no because they were there, no Freud or Jung to explain this whit realizing that they were seeming paradox. supreme examples of architec- Try saying aloud; "Why, ture. Doubtless he admired my dear, you know our people the Parthenon, but not so have simply no taste at all. much for its purity of form as Why any French workman, or for the gaudy colors with Italian ditch digger, or Ger- which it was then daubed. man peasant, or heathen In brief, we hold that there Chinee, has ten times as much CECILIA HANSEN AND DR. WALTER DAMROSCH is no evidence to support the appreciation of good art and contention that the American Two artists recently heard on Sunday evening Atwater-Kent radio hours. Miss music as the taste is on a lower level good average Hansen presented a violin program splendidly played, although the program numbers American. to than that of other countries They seem were hackneyed. Doctor Damrosch led his New York Symphony orchestra in a of the take naturally to the bettah special program for the International Tests, which was unfortunately cut short on (speaking always things." some of the stations of the "chain" by an sos call in mid-Atlantic "average man's" taste.) 668 RADIO BROADCAST APRIL, 1926

But let not our impassioned defense of the Such names as Beethoven, or Moussorgski to go to the movies when pa finally puts in a aesthetic discrimination of our fellow citizen or Debussy formerly filled our lowbrow with belated appearance. Ma gives pa a good lead you to suspect that we consider his taste wide eyed fright, gave him the blind staggers, bawling out and is not at all appeased by his worth a row of pins. Our argument is entirely lashed him into a frenzy of terror. And now he explanation that he was delayed by a cop who relative; we simply believe he is no worse off has found that his fears were groundless; that wanted to arrest him for jay walking. Pa, it than any foreigner of the same intellectual strata. even the baby can listen to these names as seems, tried to walk into a truck which brushed For the taste of the American nation is they come in via the family receiving set, perhaps by his leg. incontrovertibly low. It could adorn itself even to the tunes themselves, without dying But suddenly it is suggested to ma that the with a parasol and still walk under a dachshund of some mysterious blight. truck drivers might be sued ! Then pa is quickly to the small discomfiture of the beast. Our His curiosity is piqued. Who were these shifted from the role of doddering jay walker to newsstands are loaded with printed rubbish, our men? Did they ever run for alderman? Could that of martyr. theaters are decadent and demented, our they stand a show against Irving Berlin? And In a few moments he is quite dead and buried, music is punk in proportion to its popularity, and lo and behold! if he has not been too thoroughly the suit is set at $2000 and the receipts budgeted our movies . . . ah, there is exhibit A ... inoculated against them by heredity, he finds out and all but spent. Pa is now a wounded fifteen years of almost unrelieved drivel. himself actually enjoying them. Voila ! The hero and the truck driver indicted as a criminal However picture us not as sitting here gnash- deed is done! Our lowbrow has found a new menace to the safety of honest citizens. The ing our hair or tearing our teeth over the fact. source of amusement. He has not been "up- dialogue working up to this right-about-face On the contrary it disturbs us not a bit. If the lifted." He has not been "cultivated." He on the part of Mrs. Dorn is well written and magazines on the stands and the movies at the has simply stumbled upon something as effective humorous in a broad fashion. theaters actually represent what the great mass in another way as a bag of peanuts, or a game of Then the twist is introduced: Bill, the son, of world. of the people want, so be it, and well and pinochle, in assuaging the griefs this enters the room, disheveled of appearance and good. One book read for enjoyment is worth And radio will be a tremendous boon to those terror stricken of mien. He announces that he three books read for uplift. who imagine they are already possessed of a has been out driving in the family Ford; that a Yet our peace of mind is occasionally dis- polite and enviable taste for music. More often man walked right in front of his car, that he turbed by the suspicion that perhaps this than not, an imagined appreciation of music is at struck him, and probably killed him! The nefarious fare doesn't exactly reflect the desires bottom simply an appreciation of all the frip- consternation of the family is augmented when of the masses. Perhaps they, or some of them, peries and gew-gaws that deck it. The cut of Bill says they will probably be sued by the man's could be getting a bit more entertainment out the soprano's gown, the twirl of the violinist's widow and four orphans. Ma then executes of something a little better. If so it would moustache, the presence of the "400", and so another right-about-face and discourses at seem an economic waste for them to be content forth, are of greater interest to a large pro- length about the carelessness of pedestrians and with inferior substitution. Which brings us back portion of concert goers than the music itself. the injustice of the widow's presuming to sue to the subject on hand the influence of radio on Attention to the concert is frittered away her innocent little Bill. the taste of the nation. through the eye. What with attending to the An amusing situation, we grant, but how Radio, we conclude after some pondering, will gymnastics of the conductor, the foot work of the was it arrived at: Bill, after witnessing his have no vast and far reaching effect on the tympanist, and the amazing alertness of the family's absurd shift of ground, breaks into hemi- it's all a nation's taste. But far from lowering it, as has piccolo player, small part of the cerebral merry laughter and announces that joke, been prognosticated by the pious pessimists, it spheres is available for following the music. he never hit anyone. This announcement, will, if it reacts upon it at all, more likely im- The remedy, in the case of concert halls, is to which is supposed to constitute a climax, is, prove it. And for several good reasons. darken the auditorium. But this, few impre- as a matter of fact, a silly let down, and takes Taste in art, like taste in anything else, is the sarios have the temerity to attempt. Their away whatever merit the play hitherto had. index of our ability to enjoy the more highly business is to fill the seats, and plenty of light It is irritating as it discloses the author as trying civilized forms of entertainment or stimuli. wherewith to peruse the programs is the demand to put one over on the audience. In other Our friend Mr. Mulligan gets an immense kick of their clientele. Individuals feeling more words the situation is not developed but forced. off in the third act out of a prize fight. Our friend Mr. Van Peyster rabid on the subject than we have gone so far It is like killing the husband gets an immense kick out of a George Bellow's as to protest that "no executive artist should to solve the unsolvable triangle problem. picture of a prize fight. And though we are ever be visible to the audience." We vaguely inclined to suspect that Mr. Van Peyster's en- recollect that a concert hall in London made the A Plea for More Novelties on First joyment is a bit more acute, there is no way to experiment one time of screening the stage. Class prove it. More power to both of them in their Radio is, of course, the complete answer to this Programs varied pursuits! problem. The listener, of necessity, does HANSEN, violinist, sharing a But perhaps Mr. Mulligan might likewise get naught but listen. So we can not help but program with Florence Austral, soprano, a kick out of Bellow's prize fight paintings if he believe that in the long run this training in CECILIAwas heard in the third of this were ever exposed to one. And then what a listening exclusively will have a demonstrable year's Atwater Kent concerts. Miss Hansen's contri- desirable state of affairs would have been effect on the mass of musically inclined people. bution to the concert was as follows: reached: Mr. Mulligan could spend his days enjoying fisticuffs and his evenings enjoying The WGBS Prize Play a Poent . , . pictures of fisticuffs and thus be assured of six- teen hours a day of happiness. to our desk a copy of Sue 'Em, But all fooling aside, it is in just this way that the radio play which won first prize in radio is likely to prove of service. It is exposing COMESthe contest recently conducted by WGBS the American nation to better nightly things and which was acted over the air for the first in music than it has been accustomed to hear. time some months ago by members of the Among the millions thus exposed to good music Provincetown players. are some few who were not vaccinated certainly The title page makes known that the author against it at birth, and they will, as they have is Nancy Bancroft Brosius, that it is published been doing, "catch" it. by Brentano's, and is the first radio play printed To that music is not heard radio say good by in America. as has been said by some critics is simply to Unfortunately (or fortunately?) we didn't confess an utter ignorance of what is being hear the play presented, but we have just read broadcast. For good music is being broadcast, it through two times the second trip being indifferently performed in many instances no attributable only to our burning desire to dis- doubt, but nevertheless good music. cover, if possible, why it won the prize. That The man in the street, like the man in the discovery we have yet to make. We dismiss the jungle, has a tremendous fear of the Unknown. most ready answer that it was the best one Offer him an artichoke and he will bristle at the submitted as a rather too unkind reflection on brow and foam at the mouth. Conduct a nation- the other contestants. wide with the advertising campaign slogan, The characters are four: Mrs. Dorn, "middle ARTICHOKES FOR FOLKS " HEARTY aged and of settled disposition her henpecked and he will deposit his pennies in the Piggly husband, the "flapper" daughter Effie, and the Wiggly for dozens of them. son Bill. The family is sitting around waiting APRIL, 1926 WHAT LISTENERS THINK OF BROADCASTING 669

have been "played to death" on the radio, the eight directors of the concert orchestras whose programs are featured weekly by station WRC, at Washington, will for one week include in their programs only those new-old compositions which are seldom, if ever, heard on the concert stage or on the air. Working in cooperation with Ralph Edmunds, Program Manager of station WRC, the eight directors will search their libraries for musical compositions whose melodies lie half-forgotten on their shelves, and will eliminate from their programs any numbers that they themselves have played in radio concerts in the past year or any which they may have heard played by some other orchestra. This innovation was decided upon following numerous requests from listeners for "new" music, instead of the almost continual repetition of selections which in many cases have become prevalent during the past six months. So far, a list of more than a hundred such compositions has been compiled by Mr. Ed- WILLIAM DIEFENDORF munds and submitted to the directors for their FRED SMITH consideration. Included in the programs for the A well known performer on the musical saw who "music revival" week will also be a number of Formerly program director of WLW at Cincinnati, International and the behind the was heard during the recent original compositions which are being written lately guiding spirit splendid music Tests from WHAZ, at Troy by the directors and members of their orchestras. and entirely unique civic programs the Cincinnati Chamber of Com- A second list of more than one hundred and fifty sponsored by has been all of which are merce and broadcast through WSAI. Business a selections made, placed oh why, couldn't we have heard something men of that have subscribed more than definitely under the radio ban for the week. city little less threadbare from her? $15,000 to support twenty monthly programs Dvorak's Humoresque, Massenet's Meditation, which have featured such artists as Fritz Reiner, Is It too for the and the rest of the above pieces have become Early Burlesque and the Cincinnati Symphony Orchestra, hackneyed for the very good reason that they Marguerite Lizsniewska, Mieczyslaw Munz, Program? Francis McMillan, and Paul Althouse. Edward are beautiful tunes. So charming in themselves of the Chamber of is Chair- 1 Hoff, Commerce, that the efforts of the vilest cat gut OME( time ago it occurred to us that radio J. they defy man of the Committee of sufficient Broadcasting scratcher to completely disguise their beauty. had attained age and Ever assured of an enthusiastic S accumulated enough foibles in the ageing reception, they that the interior of the House of Commons had been have become fixtures on the of for some intrepid station to undertake a bur- repertoires every bombed, and that there had been a massacre of people fourth rate vaudeville or radio fiddler. lesque program, poking fun at the broadcasting in St. James's Park. A realistic touch was given to the terrifying details sounds as though of distant But nevertheless are. Of game and possibly effecting some reform through by hackneyed they explosions, the tumult of terror-stricken crowds and of mild satire. As we rotated the course any alert musical theorist can furnish the medium the crash of falling buildings. The listeners-in the news and soon the news- contradiction that a idea in our mind we were struck by the limitless spread proof beyond great compo- paper offices everywhere were bombarded with tele- of for sition can never get old, no matter how often it number opportunities screamingly funny phone calls from people anxious to get further details. fact al- These offices were kept busy all day reassuring is heard. aside from the facts of burlesque that are offered. In we had today But, theory, frightened inquirers, for the rumors were still circulating most reached the of to some station the case are we do get tired of hearing the same point writing in country towns and villages, and the fact that bad weather the arrival of the was over and over director and imploring him to hazard such a delayed morning papers thing again. taken by many persons as confirmation that the worst ran across the article And for this reason we regretted that an artist program when we following had happened. It was learned later that Father Ronald Knox had of Miss Hansen's allowed these musical in the New York Times, whereupon we decided ability been broadcasting from the Edinburgh wireless station banalities not merely to encroach on, but to 'twere better not. a series of burlesque "news items" and it seems that in the radio had failed to tune-in scon her On the many audjence completely monopolize program. LONDON, Jan. 17. Great excitement and fear were enough to hear a preliminary announcement warning could all of Great Britain and Ireland that the stories strength of her skillful interpretation she caused here and in parts should not be taken seriously. last evening when radio listeners-in, by a comedy of But the British Broadcasting Company is being se- made as a of less have just enjoyable program errors, heard on the air the announcement that a revolu- verely criticized for what is described as a bad joke and familiar, though equally worthy, selections and tion had broken out in London. has found it necessary to issue an explanation to the other were told that the National It that listeners should have been Among things they "public. regrets any thus enriched our musical acquaintanceship, ruins of unem- Gallery had been laid in by an army perturbed by this purely fantastic picture," but points had been blown out that leaving these sure-fire-hits to her weaker sisters. ployed; that the Savoy Hotel sky high, preliminary warning was given that the enter- tainment was not to be taken seriously. on at such not We ramble length Father Knox's burlesque news bulletin because this concert alone would was given with so many touches of humor that it seems incredible that what he said seem to warrant but because it is it, could have been taken literally, yet at heard it. typical of many other offenses in least one woman fainted when she kind. The John McCormack con- cert, for instance, was made up The Listeners for largely of the ditties that you, as do Speak we, sing so effectively in the bath Themselves tub. And we are not entirely con- a bit vinced that John sang them following statistics should better than we have ourselves under T* of interest. They were the stimulus of fragrant soap suds. A arrivedarn at by a canvass of Doubtless there are some more diffi- 2800 radio fans scattered through airs Mr. cult tenor that McCormack 48 states. The poll was undertaken could do more justice to than we, by A. Atwater Kent of Philadelphia but they were, in the main, lopped and its result catalogued by Carl off his program. Which seems to us H. Butman of Washington. rather like somewhat of a waste Practically all listeners agreed using a nice shiny silver cock- that there are far too many small tail shaker to mix up the baby's broadcasting stations operating in barley water. the lower wave band, and that there is too little high-class entertainment, PRIZE although many believe that the After writing the above the in- THE CAST OF THE WGBS PLAY, SUE EM chain broadcasters are giving ex- formation below came to our atten- at the New York station. Last year, a contest was Recently presented cellent service. tion. The novelty week referred to conducted by the station and the prize for the best manuscript for the Lack of variety in programs was last group was given to Miss N. B. Brosius, of Cleveland. In the photograph, inaugurated January. and from left to right: John Huston, Eugene Lincoln, Marion Berry, and Jeanie poor announcing many are as constructive Banning all musical selections that Begg. All are members of the Provincetown Players of New York stations, given 670 RADIO BROADCAST APRIL, 1926

criticisms by radio denizens of over five hundred the larger stations which frequently hook up on sets would certainly burn if they could read cities and towns. "No, there is not too much national programs with WEAF or wjz are fine, he some of the caustic complaints regarding oscillat- classical music," 2400 reports out of 2600 state. believes ninety per cent, of all the programs are ing receivers. This type of set should not be On the other hand, there is too much jazz, not worth while. The ideal conditionswill only be manufactured, one letter protests, while another according to 1420 replies out of a total of 2534 realized, he declares, when there is but one local listener claims all should cooperate to suppress answers. Short talks and timely speeches also in a city or town, and one or two good conti- them or teach the owners how to handle them. appear to hold fan interest, the survey shows. nental chains. More broadcasting of inter- Semi-technical talks on operation would help Interference from various sources is noted by national events, conventions and really good remedy this condition, he believes. more than half the correspondents; only about speakers will make for greater understanding and Just after Christmas for about three months, nine per cent. of the writers claim they have no in- contentment in radio land, he adds. Many of one writer says he never tries to listen-in, be- terference. Static is blamed by more than seventy the smaller stations, he points out, put on artists cause the kids trying to operate their cheap per cent, of those having reception difficulties, from cheap vaudeville shows, whose acts and "radiators" make the nights hideous until they and seventy-five per cent, of them admit that lines of patter are often offensive and sometimes run their batteries down or break up their sets their local or near-by stations come in the best. obscene. His statement that the programs Another fan expresses disappointment that This is believed partly due to the static handi- handled by linked stations are usually good, is Secretary Hoover hasn't put a stop to the use of cap. Code reception still causes some inter- borne out by approximately eighty-five per oscillating sets, adding that it now looks as if ference; about a third of the fans reporting cent, of the replies filed, which endorse this type radio was doomed to failure in this country interference, say this form bothers them. of entertainment. where it should be the best in the world. An A large number insist most of the interference A pertinent suggestion is offered by a fan who Ohio listener says he quits in disgust every night is due chiefly to the fact that so many stations says he can't see why these chain hook-ups about eight when the howlers and squealers are crowded into the wavelengths between 300 always work one way, that is out of New York; begin. "I would gladly pay a national tax on and 200 meters. A Pennsylvania listener He would like something from Detroit, Chicago, my antenna or set," this man declares, "if we wished three-fourths of them would sign off for Philadelphia and other cities broadcast over a could be guaranteed from the interference of good. Some say they never try to tune-in below series of stations for a change, believing there is these nuisances." This man seems to ha\e the wavelength of KDKA. The use of a selective also good talent available in those cities. spoken for a large number of listeners. set and careful tuning seems to bring in lots of A feminine fan is willing to listen to dance Some of the suggestions for improving the little fellows pretty well, and some of them offer music and jazz when there is some semblance of programs call for humorous talks sprinkled in unique programs. This fact is pointed out by melody to be heard, but objects to tuneless with miscellaneous matter, touching on the another fan, who asserts he likes some of the selections which sound as if they were written general request for novelties and variety, which smaller, independent stations better than the for noise alone. She also makes a plea for of course make it harder than ever for the over- high-powered broadcasters due to their individu- variety, pointing out that a whole evening of worked station managers. One man wonders alitys and unusual features. classical music is boresome while a solid program why practically all stations open up at almost One correspondent, an old time listener from of jazz is worse. the same hour and suggests that some start Cleveland, states boldly that, although some of The ears of careless operators of regenerative earlier, say at dinner time and carry on through

THE FLONZALEY QUARTET Heard in a recent Victor Hour, broadcast over wjz, WCY, WRC, KDKA, and WBZ. This group of musicians is internationally conceded to be one of the most perfectly balanced chamber music organizations on the concert stage 1926 APRIL, THE BEST CURRENT BROADCAST FEATURES 671

the early evening, while others come on a little later. Perhaps they would interfere less if they operated on staggered schedules. A train dispatcher is evidently needed if they all want us to ride with them. After all, we can't ride on more than one train or listen-in on more than a single wave at a time satisfactorily. Thoughtful members of the listeners' clan, point out that more instruction on reception is necessary; that dealers should be particular to sell correct accessories and, particularly, suitable length antennas, designating the proper instal- lation of antennas and grounds for new comers. Incorrectly erected and poorly insulated an- tennas are the cause of a great amount of poor reception, several correspondents hold. Faith in fairly long outside antennas is evidently still strong, as 83 per cent, of the fans listed use them, nearly half of them being between 75 and 100 feet in length. A few listeners admit they would prefer one or two good programs a week rather than a con- HENRY FORD'S OLD FASHIONED DANCE ORCHESTRA tinuous mediocre nightly performance by talent Composed of cymbalom, and sousaphone, "fiddle," dulcimer, which recently broadcast an interesting or even fair entertainment. Many offer to of old pay program time dance music over WEAF, WJAR, WEEI, woo, WCAP, WCAE, WTAG, WGR, for better wwj, broadcast programs if it is necessary, woe, WEAR, wcco, WON, and KSD so as to eliminate the amateur and inferior stations. Wolfe Wolfmsohn, first violin; Edwin Ideler, make no The calls for silent nights were not missing, subsequent reference to it. The only second violin; Herbert Borodkin, and but most of the fans reporting seem able to get viola; exceptions are Toulouse, Oslo, Rome, and Emmeran Stoeber, violoncello. at least a few outside stations when they want Munster, where the announcers state the to station's do so. This is perhaps because a large name with every single announcement A WELCOME addition to the percentage of those in own three-, Chicago throughout the program. writing four-, * district's dinner music is the or five-tube sets. Out of 2660 fans replying to programs offering of the KDKA Little concert the question, 40 per cent, operate five-tube sets, Symphony DROBABLY the most irritating mode of through KYW. This is effected KDKA'S while 22 per cent, own three-tube receivers, and through announcing in present use is that em- short wave relay which connects that 13 four-tube sets. Very few boast of more tubes system ployed by WBBM, Chicago. An oh so cheery, station also with WBZ and KFKX. oh so and even less seem content with single tubes or democratic voice greets the listener before crystals. This would indicate that listeners are each number with a "Yes sir! Yesma'm! This A MONO the novelties introduced is the slightly better equipped that a year ago. Most recently so-and-so Company station!!!" *> was the Ford Old Fashioned Dance of them get loud speaker volume on some station Henry Orchestra broadcast WEAF and Associ- as 85 per cent, of their sets are equipped with through IN NOTING the recent high spots in radio ates. Besides the still violin this 1 loud speakers. Of these, horns seem still most up-to-date programs we first take occasion to welcome quartette boasts of a the prevalent, although the more modern types are cymbalom, sousaphone, again Victor Hour. The series started out and dulcimer. coming into use gradually. auspiciously with John McCormack and Lu- cretia on These folk who wrote in about their sets, Bori, whose heels quickly followed /^\NE of the best of to wet A but B the permanent features on Titta Ruffo and the appear prefer batteries, dry ^-^ Flonzaley Quartette. KGO'S is the concert the batteries, although a few have installed elimi- program, by station's Little nators. Symphony Orchestra every DUT what we consider the best news since afternoon L* Sunday at 3:30. The orchestra is last is the Complaints against barefaced advertising and writing winning over of the conducted by Carl Rhodehamel. Boston sales talks were also registered, while protests Explanatory Symphony Orchestra to broadcasting. remarks are made Arthur S. Garbett. For against the conduct of announcers would make by the first time in its history it has undertaken to a story in itself. broadcast its regular winter series of twelve STIMULATE a greater interest in the concerts Saturday evenings through WEEI. * operations of governmental machinery and The fact national problems, the Minneapolis League of that season ticket holders have com- 'Broadcast filled ^Miscellany Women Voters has arranged a series of 20 pletely Symphony Hall for the last two to the exclusion of weekly talks from wcco. These are to be given seasons, the general public, was a at 2:00 p. M. every Tuesday. Each week the determining factor in causing the trustees NOTABLE contribution to recent radio to authorize the speaker will devote five minutes to answering broadcast. was the series Free offerings of Chamber questions which the listeners have sent in. The Music A Concerts by the Lenox String subjects to be discussed are: "Is Woman broadcast Quartette through wjz from the Suffrage a Failure?"; Why Vote?" "How Can Communications Music in New York Library City. Women Help in Bringing Universal Peace?"; These concerts were made possible through the "How Does Vote Affect the My Home?"; Mr. of Mrs. S. John Wallace, courtesy Elizabeth Coolidge, who has "City Government?"; "State Government?"; taken a RADIO BROADCAST, great interest in the development of "National "Women in Government?"; Indus- Garden musical in the City, New York appreciation American people try?"; "Women in Professional Life?"; "The and has sums of spent large money in the ad- Child at Play."; "The Child at School." SIR: vancement of the education of the people along I have been hoping that someone would take these lines. She is the founder of the Coolidge THE stations we receive on our f~\f regularly a crack at those announcers who urge us to Chamber Music which is an ^-' Festival, annual set, we know of none that flaunts its call "write in." Why always "in?" Can't they event of three or four days duration in letters and location more Washing- frequently and per- say "out" or even "round about" once in a ton each Autumn. It is Mrs. Coolidge's aim sistently than WJAX at Jacksonville, Florida. while? to institute free music concerts in in Since it is a every city municipal station, the explanation Also something about the announcers who the only- United States and make the public libraries lies, in its desire to the probably, impress name have "little" songs, "little" compositions, etc. the seat of musical as well as literary education. of the on the world at village large. Personally, Why not have something of a fair size or perhaps It was she who paid for these concerts and her we're over-impressed. even large now and then? only stipulation was that the works of at least I grow somewhat tired, too, of the announcers one American composer be played at each con- "THE custom in we are Europe, told, is to who are so sure we are enjoying their cert. * programs. announce the name of the station at the BEECHER OGDEN. The Lenox String Quartette is composed of commencement of the and program, then to Pleasantville, New York. AS THE BROADCASTER SEES IT

Drawings by Fran^lyn F. Stratford

How Radio Has Progressed

"E ARE so constantly bom- in on that line, you must follow it to the while the children were listening to the barded with the idea of grave. If you build one machine, you bedtime story, and set them to yowling 'progress," nowadays, that must shortly build another and better one, instead of putting them to sleep, and W!we are apt to conclude that or some one else will. And so Progress has hashed up the phonograph music, which it is a notion of universal validity, which you by the neck. Progress, therefore, is a was otherwise grand. Reception, of course, has always existed. This is an error. specialized and narrow thing, valid only in was on headphones. The sets were one- Progress, as a matter of fact, was first certain applications. To us it seems uni- and two-tube affairs, inductively coupled, boomed in earnest by the late Victorians. versal, because we are interested only in with tickler regeneration. These sets No doubt it existed before, but it was taken the things to which the concept of progress were decidedly better than the average, for granted, and no one got excited over is applicable. having been built by professional operators it. Presumably a civilized Greek of the Of these things radio is one. Here is a with all the controls necessary to achieve EC's realized that he was housed and fed field, taken by itself, in which the advances the best results, and perhaps a few in better, and more comfortably situated in are evident to any one who has not been addition. They were not selective enough, general, than his remote ancestors, but he traveling in Tibet for the past five years. however, to achieve freedom from inter- did not feel the urge to deliver lectures on (The qualification may not be an apt one; ference, aggravated by the distance of the the subject. As for the mediaeval mind, by the time this gets into print, radio may broadcasting station (some 200 miles), the idea of progress was as remote from it have invaded Tibet.) and the relative nearness of the spark as oil circuit breakers. Let us go back those five years. That, transmitters of ships rounding the Cape The reason for this deplorable lack must of course, is an arbitrary figure. As we and sending on 300 and 450 meters. lie in the fact that these people were not have often emphasized in this place, radio At this time a majority of the listeners blessed and burdened with machinery. was very much alive before 1921; even were probably still in the skilled class Their main concern, after the primal com- radio telephony was not a novelty to those mentioned above commercial or amateur forts had been taken care of, was with "in on the know," and there had been wireless telegraph operators having a little the things of the spirit. Hence they did stations properly describable as broadcast- fun with telephone reception. Their num- not believe in progress, probably never even ing stations before that time. But it was ber was limited, while the number of thought of it. For it can hardly be denied toward the end of 1921 that radio became potential unskilled listeners was enormous. that as far as spiritual comfort is concerned, a subject for public participation, rather The latter were rapidly catching up and one age is no better off than another. If than the esoteric preoccupation of a few passed the first group very early in 1922. we assume that happiness is the aim of engineers, operators, and amateurs. And, The receivers offered for sale to the lay life an assumption which holds good for entirely aside from the "1 did it first" public at this stage were very crude. me, and you are free to accept it or to claimants, that is when broadcasting as we Most of them were built for only one wave- make your own assumption, as you please know it had its beginning. length (360 meters), and the only variable then certainly a man of this age has made Toward the end of 1921 I was living up element was to enable reception of signals no progress over a man of the age of Pericles on Cape Cod in Massachusetts, not far of this frequency with various sizes of or even Rameses. Or, if you like, go back from the beach where, in his day, Henry antennas. The best known of them was r further. These men were as free to learn, and Thoreau paced the sands and declaimed single-circuit crystal receiver in a small to make love, and more free to get drunk, Homer to the ocean waves; but my occupa- box, with switch taps for varying the in- than we are, and they had less to worry tions were more prosaic. I was engaged ductance of a single-layer solenoid. The about. I doubt if 1 am happier than they in my trade of wireless telegraphy, to- tuning was so broad that with a large an- were, all the way back to Pithecanthropus gether with about forty other men at a tenna and everyone tried to get as large Erectus. So much for progress in that transoceanic-and-marine station. Some an antenna as possible it did not matter sense. of the operators, at their homes in the much where the switch was set; everything But when it comes to machinery, we evening, listened to broadcasting from from 175 to 500 meters came through, face a different situation. As soon as Newark, New Jersey, and spoke to me more or less. Then there were some better machinery enters the door, progress breaks about it. I was not much impressed, sets, also of the single-circuit type, but with in at the window and sits down in the best having often heard wireless telephone a variometer adjustment and a more chair. There are no perfect machines, transmission before. The trouble with it, scientific connection of the detector circuit and few good ones. Some, however, are they said, was the interference; various to the antenna inductance (through a better than others. As soon as you start ship and shore stations broke in continually suitable tap arrangement on the latter) APRIL, 1926 HOW BROADCASTING TO-DAY COMPARES WITH THAT IN 1921 673 so that the tuning was as good as one could if we are not careful, and they operate on Bori takes a top note. Still, it may be expect of such a simple arrangement. Of one or two tuning controls. They are a said that there are ten or twenty stations course the more complicated three-circuit, thousand times as sensitive as they need in the States which are pretty good, con- four-control tube receivers favored by the to be for anything but extreme long dis- sidering that their whiskers are not yet amateurs were available, but bold indeed tance reception, and are used most of the beginning to sprout. They are connected was the novice who essayed to operate one time with the volume control near its by quiet and well equalized lines, their right off the bat. A three- or four-control minimum position. The output can be frequency characteristics are satisfactory, receiver nowadays usually has most or all made as loud as the original performance their power is fairly adequate, their staffs of the dials lined up so that for a given in the studio or concert hall, without know something about music and practical setting of one, the others should be ad- noticeable distortion. The users of such acoustics. All in all, the look backward justed to about the same numbers on the sets need not be cautioned to hold down is flattering, and the prospect encouraging. scales. Besides, in the meantime the the volume in order to keep the quality What with static, forced sales, copyright public has been educated by radio periodi- decent; they can get all the output the disputes, and lack of wavelengths, we are cals, trade catalogs, and comparison of window panes can stand, without hashing certainly not out of the woods, but one notes on the 8:13 into town. But in up anything. As for headphones, most does not have to be a member of the Ki- 1921-22 the more complicated receivers radio listeners no longer associate them wanis sodality to recognize the fact that were still operated by intuition rather than with radio sets at all. Modern loud we are on intimate terms with the goddess figuring, and if you lacked the intuition speakers transmit all the frequencies from Progress. you had to fall back on the crystal re- 70 to 7000 per second, and if they have ceivers, which were therefore in the vast serrations they are not as high as a cathe- Among the Broadcasters majority. The typical radio fan was a dral door, nor as close as saw teeth, so WBAL slightly deranged but harmless fellow who that the human ear, which is no precision at sat all evening with a pair of headphones instrument itself, takes little note of them. new 5 kw. transmitter on his ears, tinkering with a wire which he These sets not only work well, but they THISBaltimore, Maryland, uses the called a "catwhisker" wherewith he gently look well. The programs, in large part, "mixing panel" idea in solving prodded a "crystal," muttering at inter- are on the same level. More and more its studio pick-up problems. Instead of vals, "Maybe 1 can find a better spot on they are being supported by professional employing one microphone, which must be this d d piece of galena." So much for musicians, and, among the greatest artists moved to the proper position for proper the technical equipment. and aggregations of artists, there are now balance on vocal solos with instrumental And what did he hear? Mainly phono- more who have broadcast, and are going accompaniment, orchestras, and the like, graph music riding on top of great splashes to do it again, than those who still fight WBAL utilizes three microphones with of telegraph code. Although, for a time, shy of the microphone. Scarcely an event separate controls which are under the hand very respectable artists broadcast for the of public importance is run off without that of the supervising operator. The electrical sheer novelty of the thing, and a ride to little instrument in the foreground, and energy fed to the set from each of these Newark in a Packard with a lively party half of them are planned as much for the microphones may be increased or decreased at the Robert Treat following. Then, "invisible audience" as for the people at will, without noise or other complica- when the cute little fish began to grow up physically present. As for the broad- tions, so that one microphone may be and threatened to attain the dimensions casting stations, it is not fitting for a cut out altogether, and another cut in, of a whale, they found it better to stay professional broadcaster to point publicly during a musical number. In other words, away from its aquarium. Also the music to their many excellencies. Nor is it microphones may be changed at any time, composers, and the custodians of their prudent, because whenever he gets that without disturbance, the only precaution copyrights, began to oil their six-shooters way all the modulators immediately go necessary being that the cutting out and in in- and to sharpen the tips of their harpoons. soft, the cat gets tangled up with the ten swinging in must be accomplished There followed some lean years, judged thousand five hundred, and the breakers verse proportion, so that the over-all by the artistic standard, but the marvel of go out and won't go back while Lucrecia volume resulting remains about constant. getting voices, and a species of music, out of the air, kept the new art, not only going, but growing. As for the broadcasting stations them- selves, they were good for their day, even though they would give a modern broad- cast engineer, i.e., one practicing four years later, convulsions and suicidal im- pulses. Their audio frequency bands were too narrow and had a great number of humps and dips, most of the tubes over- loaded, the microphones had joyfully responsive resonance peaks and were addicted to blasting; the wire lines carried almost as much sixty cycle hum and tele- graph clicking as modulating energy for the broadcasters who leased them. It was a grand old time, and I myself grow senti- mental over it after a few drinks of ginger ale but let us thank God that we do not have to listen to its effusions again, with our sensitized and critical ears. (We prodigies who did not know, five years ago, whether a 373-W "mike" had one button, or two, or as many as a vest.) Let us now regard the present. We have receiving sets so selective that they clip the side-bands off the transmitted wave, IN IQ2I, THE SPARK INTERFERENCE ON 360 METERS MADE THE CHILDREN HOWL 674 RADIO BROADCAST APRIL, 1926

Or, the pick-up of the three microphones, is two feet to one side. or any two of them, may be "mixed" to (See Fig. i, position A). produce a musical balance better than can But if she sings softly, be secured on one (assuming no physical the piano will predom- movement of the microphones). I insert inate with this set-up. this last qualifying clause because it is my Well, all you have to do opinion that in a studio of moderate size is place your microphone Microphone reasonable control B three feet from T "A" with experience and say soon as she in placing of musicians, one can do as good the lady. As a job with one microphone as with a dozen. starts you will know One microphone, properly placed, will give which transmitter to use, as results on small ensembles, and as have control satisfactory you * Microphone as any combination. The advantage of of both it is the work of "6"L the multiple pick-up arrangements is the only an instant to swing in secured when it is in the right one. Or, it flexibility adjustment X) Accompanist found during the first number of a per- may be convenient to formance that no one microphone is combine the outputs of properly placed. If there is only one the two microphones. microphone, the choice is between entering This, in brief, is the sys- Soprano at the studio during the number and moving tem used WBAL. With X Soloist it is less the transmitter, which always disturbs there much FIG. the artists and may cause a noise on the excuse for poor musical air, and letting it ride for that number, balances, blasting, etc., is within of the i.e. doing a bad job for five or ten minutes, than when only a single pick-up unit range microphone. The stunt is to a small at the best and fixing things up during the first in- available. place rug terval. In other words, the broadcaster The WBAL announcement which has pick-up location. Afte.- ten months' trial has to choose between the electrical devil reached us merely explains the purpose of Alfred Thomas, the resident engineer in and the deep sea. But if he has a number the system described, without giving the charge at KOA, has this to say about his of microphones independently mounted technical modus operandi. One way of device: his life is made a little it would be to use and controlled, doing separate amplifier Not once has our magic device failed to turn with individual controls of easier. Suppose he encounters a soprano systems gain the trick. Most any type of rug fills the bill if of unknown potentialities, with the usual the type described in this department in it is soft and of contrasting color with the floor. piano accompaniment. If she sings very the March issue ("Technical Routine in It should, however, be of small dimensions, say three or four feet. It is a few feet from loud, it may be well to place her five feet Broadcasting Stations: Monitoring"), the placed the the distance depending wholly from the microphone, say, while the piano outputs being combined after two stages of microphone, the voice of the to be heard. low power amplifica- upon person the assumes a tion. This has the ad- Unconsciously, speaker position on this rug before the microphone and there of vantage including remains until his remarks are concluded. Sub- a number of parallel consciously he regards this piece of floor-covering chains: microphone with its imaginary boundaries, as an island of plus amplification up safety, and he is disinclined to venture elsewhere to the five watt level, about the stage. As a result, broadcast listeners say; and if anything are enabled to hear the talk in full. Otherwise, comments would be lost to happens to one of the some of the speaker's the invisible audience. amplifiers or micro- phones, that particu- Ministers, it is further stated, are the lar system is cut out best behaved subjects before the micro- one as a unit, leaving phone, while political speakers are the or two others still worst. How about the Rev. Billy Sunday? It has functioning. I have my doubts about the rug remedy the disadvantage if that acrobat-evangelist should be per- of complexity. A suaded to broadcast. method of using a Dr. D. E. Phillips, a psychologist of the multiplicity of micro- University of Denver, makes the remark phones, individually that "KOA'S plan to prevent a speaker from controlled, "input- taking gymnastic exercises on the lecture ting," as Zeh Bouck platform is indeed novel." With a heavy says, to a single am- heart I must take issue with the eminent plifier, is shown below scholar of the U. of D. The stunt is a under "Technical good one, but it is neither novel nor orig- Operation of Broad- inal. Public address operators in vari- casting Stations: ous parts of the country have been using Multiple Pick-Up." it for years. In fact, if I am not mistaken, KOA and I'm not, it was mentioned in the paper on public address systems by Green and FROM KOA, the big Maxfield in the journal of the A.l.E.E. fellow in Denver, for April, 1923. comes the news that the technical staff at sketch shows the of the THE MIXING PANEL AT WBAL that station are util- layout studio of with izing a "magic rug THEnew Chicago WJJD, Part of the standard sooowatt equipment at that station. The mixing to keep transmitter at Mooseheart, Illinois. The panel for various studio microphones is that av the extreme right of the remedy" consist of rooms the illustration public speakers new quarters eight APRIL, 1926 DETAILS OF SOME BROADCASTING STATIONS 675

"Radio Suite" on the twenty-fourth dining rooms, and floor of the Palmer House, which, when the other points second section is completed, is expected reached by the to be the largest hotel in the world. The public address director of WJJD is Jack Nelson, one of the system. For ex- pioneer broadcasters of the Middle West. ample, any one of The new studio arrangement was not the five orches- thrown together haphazardly, but was tras which will STUDIO PARLOR carefully planned by Mr. Nelson and the play regularly in architects of the building. Under these the Palmer House conditions, the people in charge had a will be available relatively free hand in arranging things as in this way. past experience indicated they should be. One important No doubt in the future new is many buildings item that STUDIO No.l will include broadcasting facilities in the frequently neg- plans; Mr. Rothaphel's New York theatre, lected in broad- now in process of construction, is an casting studios example of this evolution. has not been THE CHICAGO STUDIO OF At WJJD there are two studios, to facili- overlooked in this WJJD It is located in the New Palmer House and for the station tate rehearsals and avoid delays in running instance. This especially designed off the programs. No one who has not is the matter of tried to get a thirty-piece band out of a ventilation. It is stated that more than cast transmission and broadcasting in moderate sized room, with the air blank $10,000 was spent for ventilation in the general. There is certainly a paucity of or desperately "plugged" until they could new quarters of WJJD. such works. However, many valuable be out and the next number set got up, WFBG papers have appeared in the Journal of tbe can appreciate what a help an auxiliary A.I.E.E. and the Proceedings of the I.R.E. studio is to the program and operating is a loo-watt outfit at Altoona, A list of the more conspicuous ones was staffs of a station. By means of buzzer WFBGPennsylvania, owned and operated given in this department in the April and light signals the operator in the room by the William F. Gable Company and 1925 RADIO BROADCAST. Every broadcast of between the studios keeps control the the Times-Tribune Company of that city. engineer and operator should read the proceedings. The artists in the studio are Walter S. Greevy is the director; the chief articles therein named, if nothing else. directed by means of electric signs reading, operator is William K. Aughenbaugh. However, a complete file of the journals "Get Ready," "Broadcast" (in red), and WFBG broadcasts regularly from eighteen mentioned for 1923, 1924, and 1925 would others like "Too Loud," "Too Soft," remote control studios, over leased wires, be a good investment. There are also "Too Much Piano," etc. and about once a week they pick up a valuable papers in the Bell System Technical A motion picture booth is provided for special program, using portable equip- Journal, G. E. Review, and other technical taking pictures of celebrities who broad- ment. The shortest loop is 3000 feet and periodicals. We are thinking of summariz- cast. Here the necessary cameras and the longest about 4 miles, not counting ing one such article each month, in its lights are stored, ready for use and out of central office wiring. A. T. & T. circuits practical aspects, for technical broadcasters the way, and cables leading direct from are used In the main. who are so situated that the originals are the main power switchboard of the hotel The transmitter is a Western Electric inaccessible to them. But we can do that furnish the currents necessary. 2A, with 100 watts output, fed by a 24^ only if we have reason to believe there is a Microphone stands are considered passe speech input amplifier and equipped with decided demand for such material among at WJJD. Instead, the transmitters are the 36 receiver and KS22J3 power panel. our readers. How do you feel about it? suspended from eight-foot decorative There is also a set of storage batteries You can have what you like, but you must wrought iron arms adjustable to any height for plate and filament supply. The set let us know what it is. and position. This eliminates microphone reaches out 600 miles on evening programs. WLS wires trailing around the floor, with the In making some pleasant remarks about possibility of people tripping over them. this department in its relation to broad- A town with an ancient and Mediter- Loud speakers placed in the Studio casters, Mr. Aughenbaugh comments on INranean name, Crete, Illinois, there is Parlor, each of the rest rooms, the Direc- the lack of books about land line broad- situated the new jooo-watt transmitter of tor's office, and the Control Room, permit the program to be followed at all of these points. The reception parlor is furnished on the style of a well furnished living room, with chairs and lounges for waiting artists and guests. The windows between the studios and the reception room are so draped that the guests can see into the studios, but the artists, while on the air, cannot be disconcerted by a view in the opposite direction. This arrangement gets around the difficulty encountered when the studio is glass enclosed on one side, of causing the artists to feel as if they were in an aquarium. A twenty-pair cable connects the control room of the WJJD suite to the public address control room of the hotel, so that public address service can be provided in any portion of the hotel on radio programs, and, conversely, the station can pick up broad- cast material from any of the ballrooms, THE ARTISTS FEEL AS IF THEY WERE IN AN AQUARIUM 676 RADIO BROADCAST APRIL, 1926

window is a miniature theatre frequency limits. It has not yet been which is to be open to the pub- introduced into so this is "> broadcasting, E2Z3jL__O-WW\^ lic. It seats Ml about 50 people, as far as we shall let it worry us for the who hear the program through present. loud speakers while watching the broadcasting. The usual Radio Lingo, Past and Present reception room, offices, operat- Miscellaneous and rooms are of Influences: The Novice M2E 3 O ,/WW ing battery course included. in the radio art, and BEGINNERSthe public in general, say, "My Broadcast Transmitters radio" where initiates refer to and Tuning "my receiver," or "my receiving set" or, more loosely, "my radio set." The 23 O^WW I lajE || I OMMENTING orally broadcast listener is interested only in 6V B. on the substance of receivers, so a receiver is a "radio" to " c my remarks on Broad him. Waves and Sharp," in the The same slackness is evident in the March issue, in which I let nomenclature for condensers. FIG. 2 "23-plate" loose a few growls at the broad- The beginner is not interested in capaci- cast listeners and operators tance, which is a concept and takes some studio in the WLS, with Hotel Sherman who labor under the delusion that a c.w. experience and thought to grasp, but he Annex in Chicago. This well-known sta- telephone station can "sharpen" its wave can see and count, and so condensers are tion is maintained by the Sears-Roebuck in some recondite manner, Mr. John sold by the number of plates rather than Agricultural Foundation. Curtis D. Peck V. L. Hogan, the well-known consult- by the essential factor of capacity. We is the chief operator. ing engineer and Past President of the may expect a widening gap between the is located The power plant on a two- Institute of Radio Engineers, points out engineering and selling terminology of and-a-half acre plot on the Dixie Highway, that there is one case in which a broad- radio, for the engineering interests will just south of Crete. The site is landscaped, casting station may contribute to broad certainly not give up their ways of cal- with ample drives and parking space for tuning at the receiving end. That is when culating and designating, and the public visitors. The lawns cover some fifteen the carrier frequency fluctuates with modu- cannot be expected to take up the engineers' miles of ground wire, plowed in during lation. This malady is probably a rare way of looking at things. the period of construction of the station. one among broadcasting stations worth Among other influences that have The building contains a large operating listening to, but it may occur among some formed radio terminology is that of the room, an office, a reception room for visi- of the loose and flapping small time agita- sea. We have all heard the announcer " tors, generator and battery rooms, switch tors of the ether, so let it be included for say, Please stand by for the next feature closets, and an entrance hall. The con- the sake of completeness. Mr. Hogan on our program." Now, "stand by" struction is up to date in every respect, discussed this complaint in the September is a general term meaning "to be near,' including factors affecting radio transmis- and October, 1924 numbers of Popular "to be present." As a nautical term it sion. The layout and joining of metal Radio. If the fluctuations are rapid means "get ready," as "Stand by to launch lath, for example, is such as to minimize enough, such a carrier will not only tune the boats." This phrase entered radio radio frequency losses. An elaborate water broadly, but it will be noisy. I think even apparently by the nautical route, but had cooling system for the tubes, with provision in this case we should not apply the terms to undergo a change in meaning to "Wait a against freezing during the winter, has "sharp" and "broad" to the carrier, but minute; I'll be with you shortly." When been provided. The towers, measuring should refer to its "steady" or "fluctuat- two ship stations called a coast station, the forty feet at the base, and two hundred ing" nature, as the case may be. The land operator would tell one of them to feet high, are visible from the Indiana state term "broad" should be reserved for the "stand by." The early tuners had a line. tuning of receivers, and the radiation of "stand-by circuit" a broadly tuned cir- The transmitting set is a product of the spark transmitters, with their adjustable cuit, picking up any signal within a Western Electric Company. The wave- decrement. wide range of wavelengths. Many an length is 344.6 meters, corresponding to For that matter, the broadness of tuning old operator remembers the musical swing 870 kilocycles. The Army experimental of every c.w. transmitter varies with of Cape Race's "std bi" in the dim ro- call letters are A z 3. modulation. The carrier, the carrier plus mantic spark days. And now the broad- The studio on the sixth floor of the Hotel the modulating frequency, and the carrier cast announcers have it. An honorable Sherman Annex was fixed up by a well- minus me modulating frequency, are the and manly phrase of deep salt water, it known interior decorator with the aim of three frequencies radiated. Hence when has become a prefix to jazz orchestra- expressing the radio motif (on the nature emitting a note of high musical pitch a tions. of which there may riot be perfect agree- station should tune somewhat broader Past, Present, and Future ment). According to an announcement, than when its carrier is modulated down " Every piece of equipment and furniture, in the bass. Whatever broadness of tun- RADIO has passed from the the walls, ceiling and lighting fixtures ing is introduced in that way is a conse- SObackyard-spark coil-coherer stage to . . . emanate the speed, intensity, and quence of the fundamental function of the the universal communication level, and universality of the mysterious forces of station. Again, there is a practicable ways of speech have changed with it. In the air." Black, red, and silver are the form of radiation, called "single side band the early telegraph days the note or tone colors, with representations of sound waves transmission," in which the carrier and of the signals was anything. The object on the walls and ceilings, giving the visitor one side frequency are suppressed at the was just to get a sound through. The the impression that "he has stepped inside transmitter. A substitute carrier is in- Marconi spark coils, with their gastric of Einstein's brain." Well, at last some- troduced at the receiver, and the modula- growling, were supplanted by the sixty one understands Einstein. tion reproduced by the use of the single cycle spark, because sixty cycles happened There are two studios. One is 55 feet side frequency which is radiated. This to be handy. Gradually aspirations for a long and 20 feet wide, for orchestras, method is very economical in that it re- musical note took form and the question bands, and dramatic productions; a smaller quires a much narrower frequency band arose, "How's his note?" when one was studio accommodates soloists. Separated per station, and consequently allows more speaking of a station. A decade later the studio a from the larger by plate glass channels to be crowded between given question is, "How is their quality?" APRIL, 1926 SIMULTANEOUS USE OF SEVERAL MICROPHONES 677 when people discuss the merits of a broad- transformer IT ahead of the first tube; dual microphones, and that a true zero be casting station quality being the effect the other extreme terminal of the potentio- obtainable, so that any microphone on the of a great complexity of notes and their meter chain goes to the other side of the panel may be cut out completely if desired. faithful reproduction. Behind the change input transformer primary. The secon- Usually telephone keys are provided, so in phrase there is an evolution from the dary winding of the transformer goes to that after the gain on a transmitter has relatively simple to the relatively com- the tube. In the output of this tube there been set at zero, its circuit may be opened plex. may be an over-all gain control, as de- entirely by means of a key or switch. And the end is not yet. If radio movies scribed in the March issue, supplementing The diagram shows the operation of this become a reality, will radio fans be asking, the individual gains afforded by the system with carbon microphones, but a "How's the visibility?" a decade or two potentiometers. condenser type may be used equally well hence? The value of the impedances will now be provided that its associated amplifier has given roughly. For a 6-volt battery, R a step-down transformer whose output Technical Operation of Broad- will be of the order of 200 ohms, which with matches a carbon microphone approxi- This is casting Stations the 100 ohms impedance offered by each mately (200-500 ohms.) output button of the microphone limits the d.c. then connected to the two outside posts of 4. Multiple Pick-Up per button to the appropriate value of 20 one of the sets of three, the middle post, 2 shows the layout of what milliamperes. Since, for audio frequencies, to which the frame or diaphragm terminal FIGUREis commonly known as a "mixing the buttons are in series, a normal carbon of a carbon microphone goes, being left panel" for combining the outputs microphone has an output impedance of unconnected. The output of the condenser of several microphones. The transmitters about 200 ohms. This matches such a may then be mixed with a carbon micro- are of coil as Western Electric if desired. In there M,, M s , -M 3 , the carbon type, repeating the phone output, fact, and they are fed in multiple from a yy-A. The impedance does not change in is no reason why the outputs of several single battery B, each having its own the repeating coil (the windings being transmitters of differing frequency charac- or the across each teristics not be mixed in this for resistance R,, R2 , R3 , in series, to limit alike) hence potentiometer may way, the d.c. through the microphone to the secondary may also be of the order of the purpose of securing an over-all output proper value. Each microphone feeds its several hundred ohms total resistance. superior to any of the component pick- audio output into a repeating coil, which is The primary of the input transformer has ups. Or, in the more usual situation, simply a 1:1 transformer, usually with a an impedance at low frequencies of 500 several more or less identical microphones torodial winding on an iron core, much ohms, stepped up to about 50,000 ohms have their outputs mixed, combining pick- used in wire telephone practice. This in the secondary to match the input im- ups which differ owing to the physical repeating coil is marked RC, with the pedance of the vacuum tube. This trans- positions of the respective microphones appropriate numerical suffix. Also, the former has, it will be seen, an impedance with reference to the source of sound. secondary of each repeating coil is paral- ratio of 100:1, corresponding to a turns Finally, any microphones may be swung leled by a potentiometer, P,, etc. The ratio of loii.^the impedance varying as the in or taken out at will, to suit changing variable terminals of these potentiometers square of the number of turns. conditions during a concert. All these are connected in series, as shown in Fig. It is important that the potentiometers operations are noiseless, inasmuch as the 2. One extreme terminal goes to one should be smoothly variable, to avoid variation is carried out in a circuit carrying terminal of the low side of the input abrupt changes in the output of the indivi- nothing but audio frequency currents.

RADIO GRIPPED THE FAN AS EARLY AS Works

Details of Actual Operation of a Forty- and Eighty-Meter Transmitter Using B Batteries for Plate Supply How the Record of Twenty- Six Thousand Miles Per Watt Was Attained

By THE LABORATORY STAFF

So much for whom we call without result. Then at the construction 8:15 we send out a "CQ" which is answered for the present. by 9 ECC, Floyd E. Wilkins, at Minneapolis. STATION AT MINNEAPOLIS 9ECC Let's imagine for At that time the transmitter tube, a rectifier on the floor and Note the chemical a few minutes ux-2io, was drawing 22 milliamperes at the businesslike transmitter arrangement that you are sit- 400 volts. For an hour 2 GY conversed ting out in the with 9 ECC, reducing the power with the *ITH the approach of the radio shack at 2 GY with the operators, about following results: International Tests and re- to the new transmitter. It is to get its SIGNAL try WATTS STRENGTH conditions in Garden from batteries; storage battery to ceiving power 22 400 8.8 R4 City nothing to brag about, light the filament of the tube, B batteries for 16 300 4.8 R3.5 W! 6 130 .78 R3.3 it is it became necessary to make arrangements plate supply, for obviously impossible 3.8 90 .342 R1-R3 for an expedition to the wilds of some to carry generators to the country and who " " available Not bad for a start ! 1000 miles on blooperless land. The problem of can predict the kind of power .342 less than is taken the communication with Headquarters was a from the lighting mains of Podunk? watts power by set. serious one indeed, for there was no telling It is 8:00 p. m. on the night of December average receiving

the i at m. E. S. T., the where the expedition might lead. There nth and Operator Mann (Mn) is at the On jth 9:32 p. is 2 GY connects seemed but one solution amateur radio. key with Bob Blanchard standing by to same stunt repeated. What the Test committee needed was a throw switches and be generally helpful. with 8 BZK, Paul Roth, Cleveland, using stations and mils, at volts and is reduced light, easily portable transmitter and The air is filled with 4O-meter 40 500 power receiver that could be transported with its among them is 9 DDE, John Wilcox, Chicago as follows: power to points unknown with the assur- ance that pressing the key in the wilds would awake activity in Garden City. For some time the Experimental Station 2 GY operated by RADIO BROADCAST Labor- atory and the National Carbon Company had been the scene of much activity on short waves and low power. A circuit described in the January magazine by Niklaus Hageman had proved quite successful but secured a perfectly steady note at the expense of greater plate cur- rents, and for hauling a transmitter to distant points, a foolproof, and especially a very economical circuit was essential. The transmitter shown in Fig. i is the result. The circuit is the simplest possible, the Hartley, and is shown at Fig. 2. In construction or operation there is nothing easier. A coil made of No. 8 soft copper wound on a dry cell tube and allowed to expand until the required diameter of four inches is reached constitutes the closed circuit inductance the ends of which are attached to the grid and plate of the oscillator tube. For the 40- and 8o-meter RADIO BROADCAST Photograph 10 turns are when a bands, required FIG. is used for .ooo25-mfd. condenser tuning. for ten standard Transmitter receiver and B battery compartment complete. Space is provided Another coil of four turns of the same con- throw-over switch is if an additional receiving B batteries totalling 450 volts. The unnecessary to this can be used on both transmitter and struction couples the antenna antennaa ntpnn:i is providednroviHpH for receiving. The same batteries taken circuit. receiver if proper precautions are APRIL, 1926 A PORTABLE B BATTERY TRANSMITTER 679

Antenna Current F lament Volhmeter Plate Current Meter I Antenna Series Condenser Closed Circuit Condenser

RADIO BROADCAST Photograph FIG. 2

A rear view of the transmitter showing location of component parts. The induc- tance coils are strapped to two dowel rods and kept away from metallic objects

WATTS SIGNAL was to at a roof not STRENGTH A message given 9 CCQ .3 watts and parallel with metal more than 40 500 20 R6 which he received perfectly. Arrange- 20 feet from the ground. Strong signals 30 400 12 R6 ments were made wire to communicate were received at 2 GY in the and 15 320 4.8 R4 by daytime 8 130 1.4 R3 nightly on low power. He was using at night until 1 0:00 p. m. when interference three 201 -A tubes with 250 volts of B and the skip distance made further com- At this local interference point, pre- batteries, no meters or any other means of munication impossible on 40 meters. At vented lower in but the going power, indicating resonance in the antenna. 80 meters, however, communication was meters on the transmitter could not read Beginning December 21, a nightly sche- easily accomplished. During the Inter- much lower anyway! dule was maintained with 9 CCQ except national Tests, the receiver and trans- On December i6th at 8:18 2 GY p. m., when weather conditions prevented, until mitter, set up in a farmhouse miles from connected with DCG, Frederick G. 9 Braig, January 5th when it was necessary to test anywhere, provided the only means of Rockford, 111., and with an of 1.8 input the transmitter in the field. During this communication with Test Headquarters. watts mils, at 180 he said (10 volts) signals time communication was held many times Now all of this low power work was done were audible all over the room. with other stations with a maximum input without special arrangements. After com- At m - on the of December 10:05 P- night at 2 GY of 20 watts. Schedules with 9 CM, munication had been established, the power 1 communication was established with 7th, Edward N. Fridgen, L'Anse, Michigan could be reduced, and often 2 GY got into CCQ, Vere Davis, at Missouri 9 Braymer, and 9 ECC proved conclusively that battery communication directly on low power. and the first of a series of tests was long operated sets could be depended upon for The antenna system was amusing a carried out. That 2 GY was night using consistent work. single wire poorly insulated, neither vertical a Sea Gull 201 -A tube as follows: nor horizontal and only about feet INSTALLING THE PORTABLE TRANSMITTER 35 long. SIGNAL The single wire counterpoise ran in a STRENGTH PATCHOGUE, Long Island, 40 direction opposite to the antenna and like- 19 290 5.5 R3 13 200 2.6 R3 ATmiles from Garden City, the trans- wise was not insulated. Antenna currents 7 120 .84 R2 mitter was installed in a hotel room with were never over 4 75 .3 R2 .3 amperes. 1 40 .04 Rl the antenna against a metal building All of which shows that on 40 meters,

Coil Grid Leak #8 Soft Copper Y/ire ^Antenna Counterpoise Grid Co nd. \ Dowel Rod \ClosedCircuit IYf

RADIO BROADCAST Photograph FIG. 3 Another view behind the front panel giving an idea of how simple the whole transmitter is 680 RADIO BROADCAST APRIL, 1926 there is no reason why any one can- not be in communication with any one else without a lot of expensive apparatus. Witness the fact that with 9 CCQ, a power input of .04 watts was successful in maintaining communication over a distance which represents a record of 26,500 miles per watt. It required less power to transmit the messages than it did to receive them. The photographs of the trans- mitter should give all the construc- tional details that are necessary and the simplicity of the antenna throwover switch is shown in Fig. 3. The plate batteries are contained in the lower compartment as shown in Fig. 4 and the whole outfit can be set up for operation in less than five minutes. All that is necessary is to remove the front board which has on it the key, plug in the A and B battery cables, throw a wire over a tree and spread on the ground the counterpoise or use the automobile as a counterpoise tune the antenna and closed circuits by means of the proper condensers until maximum current is obtained on the wavelength desired. The current on in- puts up to 20 watts should not be high, at least not over one half ampere. APRIL, 1926 A PORTABLE B BATTERY TRANSMITTER 681

BACK VIEW SIDE VIEW TABLE OF AUDIBILITY SIGNS

Rl Faint signals, just audible R2 Weak signals, barely readable Flexible Connection-..^ R3 Weak signals, but readable R4 Fair signals, easily readable R5 Moderately strong signals R6 Strong signals R7 Good strong signals. Would be readable through heavy QRN and QRM R8 Very strong signals. "Several feet-from-phones signals" Rubber END VIEW OF CAM R9 Extremely strong signals Handle

4 ing and distortion. So another fan, now and I and ^-~ R.H.Wood Screws --' 9 CJD, began practicingthe code, to our surprise passed the amateurs' exam- FIG. 6 ination. My first communication was with Details of the throw-over switch which changes the 9 WQ at Elmhurst, Illinois (40 meters), antenna and batteries from sending to receiving at about o'clock m. November ist. Right Angle 4 p. Next was BV at Council Bracket NEW INSULATORS 9 Bluffs, Iowa, .F.H.Screw and the third was 8 CJM, Elyria, Ohio, Now being installed Switch^ but I found trouble stations. I Jaw at 2 GY raising could get a large current in the antenna but it wasn't effective. In a month R.H.Screw.-' or so I time to -t-Panel got improve the system and although I don't get the current I did, reports are better now. Have been DETAIL OF SWITCH JAW reported at 5 AQI, Meridian, Mississippi, R 6 at about noon. Plate voltage 220, mils., 33." well insulated as possible, Since the International Tests, this and an accompanying photo- RADIO BROADCAST Photograph simple transmitter has been in opera- graph shows some Pyrex in- tion at 2 GY with complete success, re- sulators made by the Corning Glass Works and of course couldn't help seeing short ports indicating that the pure d.c. note which are now being installed at 2 GY. wave circuits and the marvelous things penetrates much better than our "high Coupling to the antenna should be loose they were supposed to do. I made my powered" outfit, for distances up to 1000 enough so that the tube continues to first successful short wave receiver last miles. The operators at 2 GY welcome oscillate under all conditions. If coupling spring, a little less than a year ago, with reports of reception and will be glad to is too close, the wavelength will jump about the intention first of listening to the short advise any of RADIO BROADCAST'S readers and no listening operator can read what wave broadcasts and was very disappointed who are interested in low power, short you are trying to send. when KDKA came in strong but with bad fad- wavelength amateur work. On 40 meters, reception is erratic, fading is bad, but phenomenal distances can be .-2 .002 mfd ** in series attained with low powers. On 80 meters transmitting distances are not so great, but steady signals, good traffic handling, and the possibility of phone transmission make it a very interesting band in which to work. A few words about g CCQ may not be amiss to show that the work done between that station and 2 GY is not due to unusual conditions but rather to the great carrying power of transmissions on 40 meters with pure d. c. plate supply. Station 9 CCQ is operated by Mr. Vere Davis at Braymer, Missouri, about 1080 miles from Garden City. Braymer is 60 miles East of Kansas City and 20 miles southwest of Chillicothe in rolling country which is still blessed with considerable timber. Mr. Davis says he "became interested in broadcast radio about three years ago and it's just a case of drifting from bad to worse, I guess. Have had an amateur's license now about four or five months and have been active about two and one-half. I became interested in amateur radio just about the same way most anybody of my age and interests does. I've always read radio magazines when I got the chance The Use of the Filament Resistance

What the Filament Rheostat Can be, How to Decide the Proper Size for Each Different Type of Tube Use and Desirability of the Fixed Filament Resistance GL

JOHN B. BRENNAN

vacuum tube, that indispensable in voltage at the battery terminals. Theoretic- Or if all r values are the same unit of the radio receiver, which trans- ally this is true but in actual practise, the battery R=r' x N forms radio into maintains its full charge over the major portion THE unintelligible signals Where N= Number of resistance units sounds that we can hear has been dealt of a single charge life. Toward the end it with at length admirably by Keith Henney in does drop in voltage but its energy has been the Decembsr, 1925, and February, 1926, issues expended to the point where the rheostat is of RADIO BROADCAST. In these Mr. useful, in the tube at 5 articles, -- maintaining voltage Henney dwelt upon the selection, use, and func- R only for a few hours. Then the battery may tion of the vacuum tube in radio circuits and be considered in need of recharging. FIG. 3 described in detail the parts played by the three Some tubes require l.i volts, others 3 volts Resistances in series retard to a extent greater it is essential elements of the tube, the plate, grid, and fila- and still others 5 volts. Therefore, the flow of current in a circuit than where only ment. that we each of these filaments economic- one resistance unit is used. The total resistance adjust is taken as the and To make this it would It is the last named, which of a series-resistance circuit is equal to the sum ally efficiently. clearer, not be to control subject for this article. We shall try to show of all the resistances employed. In a circuit of strict economy or efficiency how this filament performs its task efficiently this kind it is possible to employ two 3-volt a i.i-volt tube filament with a 6o-ohm rheostat 6-volt by the use of suitable control devices which tubes energized from a source where only i .6 ohms are required, only unless the than i Even adjust or regulate the current and voltage ap- battery voltage was much higher j. this is case. plied to it. an unusual from zero to six volts means of a The filament is the thing that lights up when presumably by variable resistance. Soft tubes, as were SELECTING THE PROPER RESISTANCE the A battery is applied to its terminals and they known not so ago, critical filament emits electrons at a given rate. The grid long required pOR the radio set constructor then, there and to obtain this end, a rheostat is the regulator or shutter which stops or lets adjustment arises a problem in selecting the proper had to be used. Sometimes the best operating is flow the electronic stream to the plate, the third size of rheostat for the tube or tubes he going was found to be five but most times not. element. In this way, feeble radio impulses voltage to use. To understand what is happening Each tube had its own peculiarities. circuit and impressed on the grid releass a stronger impulse in a where voltage, resistance, the Now, the manufacturers have advanced are it is to review the in the plate and its attendant circuits. current present, necessary design and manufacture of the tubes to such a Manufacturers of the early tubes found it law governing the use and application of re- point that the filament adjustment is not necessary to employ a control in the filament sistances in a circuit. Ohm's Law says that critical. circuit of the tube so that the tube might be where a pressure of one volt is exerted in a Keith has pointed out in RADIO adjusted to its most efficient point of operation. Henney circuit whose resistance is one ohm, then one BROADCAST that with the present tubes, a Naturally they could not use a six-volt filament ampere of current will flow. Now if the re- decrease in filament voltage below five is usually energized by a six-volt battery because the sistance is reduced to one half, the voltage accompanied a falling off in signal tone regulation so necessary would not be obtained. by Also, a increase above the The five-volt filament, energized by the six quality. slight rated filament voltage always causes a surprising FIG. 2 volt storage battery, allowed for an adjustment decrease in filament life. To prevent this it is When several resis- obvious that the old six-volt storage battery, tances, such as tube fila- FIG. I borrowed from the automobile days, must still ments are connected in Ammeterto is case in \ simple circuit compris- be retained so that a regulation of one volt in parallel as the read current r i^ ing a source of voltage the rheostat may be had to maintain the filament the majority of receivers, a resistance the total resistance of the (battery) (R) at five volts. and a means for reading circuit offered to the flow When the battery is newly charged, more Battery the current flowing of current is less than resistance of the rheostat will be in the circuit through the circuit. This arrangement is com- were only one resistance = J- to a circuit to maintain it at five volts. However, when the unit used in the circuit R parable tube where the resistance R off then this resistance is is represented by the tube filament and the ex- battery voltage drops because several paths ternal control device cut out of the circuit to compensate for the drop are provided for the flow of current APRIL, 1926 THE USE OF THE FILAMENT RESISTANCE 683

= = the tube, E rated voltage of tube, I rated filament current in amperes. Then R = = 20 ohms.

WHY RESISTANCES ARE NEEDED

"MOW if six volts is to a filament, " applied the current will be correspondingly greater than with five volts. In order to keep the current at that point stipulated by the tube manufac- turer, it is necessary to decrease this voltage by resistance to the circuit. z adding r i- r r Until a short while the one means for 1 ago Or,where the resistance of r is the same 2 3 regulating the current flow and voltage in a as, r orr then filament circuit was by means of the rheostat but lately there has been placed on the market B Where N = Numberof resistance units the filament ballast, otherwise termed filament

That is, decrease FIG. 4 regulator. they automatically the battery voltage to the correct point for A series-parallel circuit. The total resistance of application to the filament terminals. the circuit is determined by first calculating the Where r = Rheostat resistance 1 2 3 It is a circuit resistance of r r and r known fact that the battery voltage parallel , , and E = 4 Battery voltage adding that total to r remains quite constant over the major portion EI= Filament terminal voltage of its discharge life but at the end takes a decided = I Filament amperes and sudden A curve this is constant, then double the current drop. illustrating remaining : shown in It is because of this Example will flow. This gives rise to the equation Fig. 5. voltage life-retaining property of the battery that ' I where I is the current in amperes, E is the -* =^ filament ballasts have proved satisfactory for =(!)-(!) pressure in volts and R the resistance in ohms. use as filament controls. For those who desire FIG. 6 From this equation it is possible by transposing, simplicity of control, the filament ballast will the resistance value of the 'r' to find any one value where the other two are commend itself. Determining unit in the circuit above involves the use of the known. That is to say E = IxR and R = - Writers of radio articles have differed widely formula as shown. The battery voltage, the for years concerning the correct value of rheostat A circuit comprising these three factors is tube resistance and the current are usually known ; to be used in a filament circuit. The best shown in Fig. i. from these values it is possible to calculate the possible advice, and the easiest to follow is that unknown If a resistance is paralleled by another of the our old friend Ohm's Law be used. Where two same value, then two paths are provided for the factors or values of this equation are known, the resistance is necessary in the rheostat? The flow of current so the total resistance to this third can be determined by the application of answer may be found by subtracting the circuit flow is cut in half. If the resistances are added the formula. resistance at volts from the circuit resistance at to each 5 other, that is, connected in series, then = Let's look over a typical filament circuit 6 volts i. e. 2420 4 ohms as shown in Fig.6A. the current flow is retarded because the total consisting of tube, rheostat and such From this we see that with 4 ohms in the circuit circuit resistance has been increased. To battery, as that in Fig. 6 B. The filament Rof the tube where a fully charged 6-voIt storage battery determine the total resistance of a circuit where is considered as a resistance and, therefore, its is employed, .25 amperes of current will flow. resistances are in parallel the formula R = value may be rated in ohms. The battery E Theoretically, as the charge in the battery de- ls as shown in 2. is the source of the energy which lights the fil- creases, the voltage decreases; therefore, to keep J _i_ -L -L- employed, Fig. R~.~r Rz T R3 ament and has a certain voltage, usually six. The the circuit characteristics at their rated level, it Where the resistances are in series, the total rheostat r, has a variable external resistance is necessary to cut out part of the external resistance is equal to the sum of all the resistances whose total resistance we do not know, but wish resistance to compensate for the corresponding resistance is or where the per unit the same, then to ascertain. If there were no rheostat r, in the drop in battery voltage. the total is to the value of one unit multi- the main rub comes in the of equal circuit and the voltage of the battery were 5, Now advocacy plied by the number of units employed. Ex- then the total resistance of the circuit would rheostats larger than 4 ohms where only one = r t r r If the tube is to be controlled it. Of if one pressed algebraically R + 2 + 3 , be 20 ohms. battery voltage were by course, etc. or = rz where = than one R XN R total resistance raised to 6 then .3 amperes of current would flow rheostat controls more tube, the proper r = resistance unit = be since per and N number of in the circuit instead of the rated .25 amperes. resistance value may calculated usually units. This is illustrated in Fig. 3. Now by introducing a resistance in the form the tube filaments are in parallel and as such the It is possible to combine resistances in a of the rheostat r, not only is the current reduced total resistance of these filaments is figured from circuit so that a series-parallel arrangement but the voltage at the filament terminals is is This is the case where it is desired diminished. 1 produced. accordingly By applying the the formula R = etc. ~^+~j^+~^3 to know the total resistance of a circuit com- formula R = then R = = ohms which j 24 To use a rheostat of 4 ohms means that when prising several tubes in parallel with a single is the total resistance of the circuit. How much the movable arm touches the first turn of the wire rheostat in series with the tubes and battery. To calculate this total resistance, it is first BATTERY LIFE & VOLTAGE DROP necessary to find the resistance of all the tubes in parallel. Then when this value is known it is added to the value of the resistance of the rheostat. This is illustrated in Fig. 4. In the matter of determining the resistance of the tube filament Ohm's Law is employed first and then where it is desired to know the total resistance of a circuit, where such an ar- rangement exists as in Fig. 4 then the formula for resistances in series is employed. Take, for example, a five-volt tube. Its filament should be energized by the battery in so that .25 ampere of current flows the 10 15 20 25 30 35 40 45 50 55 60 65 70 75 circuit when the at the tube terminals voltage DISCHARGE LIFE IN AMPERE-HOURS is With these two known factors it is possible 5. FIG. to determine the resistance of the circuit. Since 5 When a is first used, its is above six volts. The the resistance of the battery and wire for the cir- fully charged battery voltage slightly major portion of its life, however, is at a fairly constant voltage level, the gradual drop being from 6 to 5.7 volts. cuit is negligible, therefore the resistance com- When this low point has been reached, the battery is considered discharged and is in need of recharge. will be purely tube resistance. Applying puted As the point is reached the rheostat in a filament circuit is of use because as the rheostat = - 5.7 greatest Ohm's Law R where R resistance of arm is advanced the voltage at the tube terminals is maintained at its highest point 684 RADIO BROADCAST APRIL, 1926

Table I

Various Types of Tubes and Their Respective Rheostats

uv-200 APRIL, 1926 THE USE OF THE FILAMENT RESISTANCE 685

WHERE SHOULD THE RESIS- TANCE GO? INDEPENDENT tube ' manufacturers as well as the pioneers in tube produc- tion advocate the use of the rheostat in the negative side of the A battery lead. The writer became convinced that this was FIG. procedure proper only where the rheo- The C is battery stat was to be employed to shown in its proper provide a grid bias of a few here. This place _ volts. This was is by far the better usually supplied by tapping on to a way to obtain grid bias for receiving tubes since if it is portion of the rheostat so desired to vary the grid bias voltage, that a more or less C battery may be placed in the voltage drop through circuit that portion of the resis- tance employed would pro- vide the few volts Rheostats are variable resistances with necessary for which an accurate control of the filament grid biasing. In the circuit shows voltage and current is obtained. The selection Fig. 9 how this tap is of a rheostat for one tube has already been arranged. This manner of explained and the radio experimenter should obtaining bias is unusual inasmuch it not become confused where more than one tube grid as entails first, a calculation as to the amount of resis- is controlled by a single rheostat. As it has necessary tance wire to be included in the circuit so been said, in a radio circuit it is usual to connect tap-off as to supply the necessary grid several tubes in parallel, the path for the flow voltage. Secondly, it is sometimes desirable to the bias and of current will become greater hence there will be vary grid when the connection is soldered to the rheostat less resistance to the flow of this current. In a change in voltage is impossible unless the tube circuits it is customary to employ tubes all tap-off of be unsoldered. one nature, that is, all 5- or all 3-voIt tubes. The use of a C battery provides the more The total resistance then, of a circuit, is equal convenient and to obtain bias to the resistance of one tube divided by the simpler way grid and with this change it is possible to the number of tubes in the parallel arrangement. place rheostat in the positive side of the A lead See Fig. 4. For instance, 2oi-A's have a supply so that all the leads resistance of 20 ohms. Where four are con- negative are at ground potential as in The use of the rheostat nected in parallel the total circuit resistance Fig. 9. in the positive side instead of the negative side is 5 ohms. Therefore, to cut down the battery of the A battery supply makes for more accurate voltage so that five volts are applied to the wiring, clearer of circuit filament terminals, i ohm of external resistance understanding diagrams, and the that one of the must be added to the circuit. Before, the surety part complete circuit will be at method by which the rheostat value was ascer- wiring ground potential insuring shorter leads from other units in the circuit which tained was to subtract the circuit resistance at of necessity must be connected to the line. 5 volts from the circuit resistance at 6 volts. ground Among the rheostats tested because of the Another method, also very good, is to employ difference ' in design and principle was the the formula R = where R = resistance Bradleystat, and the Filkostat. Both these of rheostat, Ej= filament voltage, E = battery devices insure a continuous, even increase

1 = total voltage and current of circuit. This in voltage differing from the wire-wound last total factor, current, is obtained by multi- rheostat which provided the increase in steps plying the current rate of one tube by the as more turns of wire was cut out of the circuit. number of to tubes be controlled by the rheostat. Voltage regulation is secured by the change in Again, using four tubes, the total current would resistance of the device as carbon discs are = be 4 x .25 amperes i ampere. Then, applying compressed by means of a thumb screw. the formula R = = i ohm. Cmttine Out the Locals

Simple and Efficient Wave Traps to Eliminate Interfering Near-by Stations By HOWARD E. RHODES

CT"HE trend in broadcasting for some time has inside of the cabinet, including the cover and curve of Fig. 10 which represents the resonance * been toward the use of higher powers, where- the panel, with thin copper. Any joints in the curves of a fairly good receiver. For ordinary ever that is possible, and this, combined with the copper sheet are soldered together and connec- reception this degree of selectivity is satisfactory, concentration of many stations in large centers, has tion is finally made between the shield and the but under some unusual condition, even greater made the problem of selectivity a serious one for minus A terminal which should, in this case, be selectivity might be required. For instance, many listeners. It is easy to remedy most of the connected to ground. This puts the entire shield the receiver might be operated at a location trouble encountered in the average receiver by at ground potential, thereby excluding from the quite close to a powerful broadcasting station simply adding a wave trap of good design, and the coils any external electrical fields. It should so that the signal strength from this station, in accompanying article reviews the subject in a very also be pointed out that this shielding will also comparison with the strength of the signals that helpful fashion. The present article is concerned eliminate any interference caused by power it is desired to receive, is so great as to produce with types which can be made very easily, and a lines, motors, etc., provided they are causing considerable interference, even though the second article, to be printed soon, will describe a trouble by setting up currents directly in the receiver is considerably detuned from the radio-frequency amplifier and detail how it func- coils. However, if this interference is reaching interfering signal. It is apparent then that in tions as a wave trap. THE EDITOR. some way this powerful signal must be impeded so as to decrease its strength.

THE SIMPLICITY OF A WAVE TRAP the increase in power of a most common of for use great many of our broadcasting piece apparatus THEin this connection is the so-called stations, listeners find need of some wave which is a filter circuit WITHefficient method whereby un- trap actually tuned to absorb the These wave desired signals may be eliminated. These interfering signals. are constructed, and cost little. signals sometimes are caused by direct pick-up traps very easily consist of an coil and a by the coils of the set so that its natural selec- They merely ordinary condenser. The are connected in the tivity is of no avail in eliminating them. This traps antenna circuit and are so that at the occurs when the set is being operated in prox- adjusted of the have a imity to a broadcasting station with the result frequency interfering signal they the exact value that the field strength in the vicinity is great very high impedance, depend- on whether the unit is connected in series or enough to induce currents directly in the various ing the coils of the receiver. Under these conditions parallel with antenna. This high impedance prevents the from down it will be found possible to hear the program FREQUENCY signal passing through with the antenna disconnected. the primary of the antenna coupling and so into FIG. I The only practical methods to be used in The curve of a well-made wave eliminating this type of interference are either impedance trap shielding of the receiver or using some form of close field coil, such as a toroid. If the set is to the set by way of the antenna system, shielding be shielded, it is necessary to line the entire will be of no aid. FIG. 3 A second and rather recently developed Another meth- method of eliminating this type of interference od of connect- the to is by the use of toroid coils. This type of coil ing trap is now being widely employed in instances where your receiver, by the induc- there is need of an inductor that is unaffected by tive method. external fields. The reason toroids are not why This very often FIG. 2 sensible to fields is to understand. magnetic easy produces satis- One method Suppose such a coil is placed in a magnetic field. factory results of connecting Then a voltage is induced in practically every without materi- a wave trap turn of the coil. However, the voltage induced ally changing in circuit the of in one half of the coil is exactly equal and op- tuning the antenna posite to the voltage produced in the other half circuit of the coil. These two voltages react against each other and the resultant effective voltage is therefore zero. This type of winding can be placed in comparatively strong magnetic fields without having any appreciable voltage pro- duced in it. Toroids are, therefore, very useful in eliminating that type of interference caused by some form of direct pick-up by the coil units of a receiver. These two methods which have just been outlined, first, shielding of the set, and secondly, using Toroid coils, are practically the only methods of eliminating this type of interference. There is a second type of interfering signal C 2 cc that also causes considerable and o trouble, against this type the two methods so far described are useless. If the signals being induced in the antenna are sufficiently strong, it is possible that a receiver may not have a selectivity sharp enough to eliminate them completely, although its selectivity under ordinary conditions may be perfectly satisfactory. Take, for example, the APRIL, 1926 CUTTING OUT THE LOCALS 687

the receiver. At the same time, these wave but since the circuit was not tuned to the traps offer a very low impedance to all oscillator frequency, the voltage which was

other i frequencies. In Fig. there has measurable represented an interfering been the in plotted change impedance of a signal. This voltage read on the vacuum wave trap as the frequency is varied, and tube voltmeter under these conditions is this a idea how a wave gives good trap represented as E t in Fig. 5, The trap was functions. At the frequency marked / on then adjusted and as condenser Ci was the the diagram, impedance as read on the varied, the voltage across L, Ca was re- ordinate of the curve is very high and corded and a curve Fig. 5, plotted, showing since this circuit would be connected in the the variation of voltage as the trap con- FIG. antenna system of a receiver, it is evident 4 denser Ci was changed. This curve shows that at this The circuit of the test used frequency the impedance of diagram apparatus a large decrease in voltage as the trap to obtain some of the data in this article the antenna system to this particular given circuit is brought into resonance with would be frequency very high, and for the incoming frequency. With the trap in that reason practically no energy could be re- indicated in Fig. 6, by the small arrows. This resonance the voltage decreased to about 15 ceived at this frequency. At the same time is important current with regard to the various per cent, of its former value. the of the fre- impedance trap to any other tuned circuits of a receiver. In a wave trap, This whole test was analogous to the case of a however, we wish to impede the flow of current in the circuit AGCa, and at resonance, the trap circuit offers high impedance to the flow of current in this circuit. There are several methods of connecting these traps. Fig. 2 shows the most common method. In this drawing L, C, constitutes the trap circuit, and Lj, C, the antenna coupler and tuning condenser of the receiving set. It is seen that the trap is connected between the antenna post of the receiver and the antenna lead-in. Fig. 3 represents a slightly different method of connecting the trap in the circuit. In this latter method, the wave is SETTING OF CONDENSER Cz trap inductively coupled to the antenna. This inductive FIG. 5 coupling is obtained by winding a few A curve showing the decrease in interfer- turns of wire about one end of the coil L,. ence obtained the use of by a wave trap One end of this new winding connects to the antenna and the other to the antenna

of the receiver. This circuit is quencies, either above or below the frequency post prac- _ tically to that of 2 with the differ- /, is very low. The efficiency with which the equivalent Fig. ence that somewhat is obtained. trap operates depends upon the steepness of the sharper tuning sides of the curve, and in order to obtain satis- WHY THE CIRCUIT PREVENTS INTERFERENCE factory operation, it is essential that a sharp ORDER to give an idea of the effective- resonance curve be obtained. IN ness of these traps, a series of experiments This idea of high impedance at resonance may were carried out in the RADIO BROADCAST Labo- ratory to illustrate how interfering signals are eliminated by the use of such a filter. The circuit illustrated in excited Fig. 4 was by means of an RADIO BROADCAST Photograph oscillator. The output of the oscillator was FIG. 7 fed into the coil L^ which was inductively Space-wound solenoid coils can be used coupled to coil L4 . This coupling was very to construct a very efficient wave trap loose so that variation in the test circuit caused no change in the oscillator output. L, d is the trap circuit and L^ C2 represents the receiver tuned to a particular station and at the input circuit of the receiver. As shown in same time receiving a certain amount of energy 1. the diagram, a vacuum tube voltmeter was from another station differing in frequency by T c, placed across the L, C2 circuit so as to measure 10 kilocycles (10,000 cycles). Under such the voltage induced across this circuit. This conditions, the use of a trap would have caused would be the voltage that would ordinarily be a decrease of about 85 per cent, in the strength applied to the grid of the first tube of a receiving of the interfering signal. Let us take a numeri- set and the extent to which this voltage is reduced by the wave trap is a measure of the trap's efficiency. I With the trap circuit L t C, detuned from the incoming frequency produced by the oscillator, the condenser G* was adjusted until maximum volt- age was read on the vacuum tube voltmeter. This indicated 7 FIG. 6 that this circuit was adjusted FIG. 8 The small arrows indicate the circulating cur- to resonance. The frequency rent set up in the wave trap by the interfering of the oscillator was then A simplified diagram of a receiver employing three stages of radio amplification, really successive wave traps signal changed by 10,060 cycles but frequency

no change was made in La C2 . require some explanation since we are accus- This circuit was, therefore, tuned to a wave cal example of such a case. Suppose it is desired tomed to think of resonant circuits as having a 10,000 cycles (10 kc.) different in frequency to receive a signal having a frequency of 500 low impedance. At resonance, a circuit con- from that being supplied by the oscillator. kilocycles and to eliminate the interference from sisting of a coil and a condenser has a low im- However, a certain amount of voltage was still another station operating on 510 kilocycles. pedance to the flow of current around the path to be measured on the vacuum tube voltmeter The antenna circuit of the receiver would be 688 RADIO BROADCAST APRIL, 1926

best results with the induc- In order to aid the home constructor in build- tively coupled circuit. Every ing up his own wave traps, the accompanying effort should be made to have table has been compiled. as good a ground and antenna For those wishing to duplicate the model as possible, but if it is necessary constructed in the Laboratory, the following to use a long ground lead to a material should be secured: one 36-turn Hammar- rather poor ground system, the lund Roberts 3-inch coil, one Cardwell .ooi-mfd. direct coupled wave trap will probably give most satisfactory operation. When using the latter method of direct coupling FIG. 9 as illustrated in This is the equivalent circuit of Fig. 9. It Fig. 2, some small change was used in obtaining the curves in Fig. 10 RADIO BROADCAST ADVERTISER 695

The Crescendon an amazing new volume con- The Crosley 4-tube 4-29 trol exclusive to The Crosley 5-tube 5-38 sets. in which the Crescendon is equal Crosley All the volume, selectivity and Hear it! to one or more additional(Ul KfVMtubes purity of tone availablem ini'i thei"c of tuned radio fre- best 5-tube set plus quency amplification $29 the Crescendon . $38 Widespread Popularity Marks Another Great Success Spectacular as has been each stride in worth while reception was exclusive to high radio achieved by Powel Crosley, Jr., never priced sets, have found in Crosley 4-29 and before has a Crosley success received such 5-38 all that they could ask of radio. The prompt and widespread recognition. Here accurate selectivity and pure tone of these in the radio plant which has made more instruments would be enough. That mag- radios than any other factory in all the nificent volume achieved through the world, every man and machine is going at Crescendon is the final touch. hour is a crowded top speed, every hour, And in Crosley "RFL" types there is a a as result of every night working day, the revelation for all. For here true cascade orders for the four new sets. Crosley amplification makes its first appearance. Even the sweeping success of the Crosley Here what was considered impossible in Musicone did not match this merciless expert opinion has been achieved by ampli- theoretical demand upon an organization tuned to fication closely approaching tube ! mass production. With the first demonstra- maximum efficiency per tions by Crosley dealers, public approval What a joy to find, and in a low priced set, was expressed in orders that have increased rare beauty, rich tone, volume subject only in volume day by day and show no inclina- to your desire, and no howling at any pitch tion to relax. by any mishandling under any conditions. This popularity is distributed quite evenly Each instrument delights the ear, fires the between the four new 4- and 5-tube sets. enthusiam of the lay technician, converts Thousands who had formerly believed that the staunchest skeptic to love of radio.

See the new Crosley receiving sets at your dealer's or write Dept.20 for descriptive catalog

Crosley manufactures radio receiving sets which are licensed under Armstrong U. S. Patent No. i, 1 1 3, 149, or under patent applications of Radio Frequency Laboratories, Inc. THE CROSLEY RADIO CORPORATION, CINCINNATI, OHIO Powel Crosley, Jr., President

Owning and Operating WLW, 6rst remote control super-power broadcasting station in America *

The Crosley 5-tube RFL-60 The Crosley 5-tube RFL- 75 A set of marvelous performance Simplicity and speed in tuning, the and beautified by fidelity of tone and decorative artistic decorative Hk/^O beauty, enhanced by the panel art panel

Add 10% to all prices west of the Rockies

BETTER COSTS LESS FOR THE ENTERTAINMENT CORNER

" \\ir "P ATlin 696 RADIO BROADCAST ADVERTISER andnov THE more stations A Department Devoted to Solv- come in ing the Problems of our Readers distinctly QUERIES ANSWERED

1. WHAT ARE THE DIMENSIONS AND NUMBER OF J. WHAT ARE THE SIMPLE LAWS GOVERNING TURNS FOR THE COILS USED IN THE "UNI- THE CALCULATION OF CAPACITY IN SERIES A UX Power Tube VERSAL" RECEIVER RECENTLY DESCRIBED IN OR PARALLEL? RADIO BROADCAST? J. C. Chicago, Illinois. will increase the clarity and vol- L. T. Flushing, New York. ume of YOUR set 4. PLEASE PUBLISH A GOOD THREE TUBE R. F. 2. HOW MAY I ELIMINATE THE REFLEX PART OF CIRCUIT FOR A RECEIVER EMPLOYING ONE REWIRING UNNECESSARY THE ROBERTS CIRCUIT? STAGE OF IMPEDANCE-COUPLED AUDIO FRE- G. C. Altoona, Pennsylvania. QUENCY AMPLIFICATION. tube for sets and NOTE: The UX-120 dry battery H. H. McC. Ohio. the UX-112 for storage battery sets reproduce more Dayton, perfectly the excellent broadcasting of to-day. These tubes handle the powerful signals of nearby "UNIVERSAL" RECEIVER COILS stations so that the quality of the tone is preserved a tap at the aoth turn from the grid end of the sec- without distortion. You can easily obtain this in- in coil units employed the "Universal" The antenna coil unit has its second- crease in clarity without rewiring your set. A com- ondary. receiver be made plete line of Na-Ald Adapters and Connectoralds may very easily by ary tapped at the center turn. The circuit have been made to THEwinding on a 2j inch diameter cylindrical connections are shown in 2 and meet this purpose. Figs. 3 Their scientific design form, 59 turns of No. 24 d.s.c. wire in the manner insures a nicety of op- shown in Fig. i. eration. Below are ELIMINATING THE REFLEX IN THE ROBERTS given three efficient CIRCUIT and easily made appli- L cations of the new 2%" RADIO BROADCAST Knockout four- power tubes. For com- tube plete details covering receiver has enjoyed widespread these and other No. 920 appli- THEpopularity for more than a year, and is Connectorald cations of the new tube mail the coupon below. still going strong. For many it has proven to be the "par excellence" circuit. How la improve storafe battery sets In such a highly specialized circuit where each Clarity and volume can be increased in storage battery sets by using the UX-112 tube in the last branch has its own important role to play, there fitted to the UV-201A socket stage. Easily by is bound to be trouble when constructors dis- means of the Na-Ald No. 112 Connectorald which provide* cables for attaching necessary extra B regard the simple fundamental rules of receiver and C batteries. Price $1.25. Mail coupon below design, or where cheap parts are substituted for complete adapter information covering use of new tubes in all sets. for those recommended.

Haw to improve sets equipped with UV-199 lutes To increase volume and clarity in sets using UV- R.F.& DETECTOR 199 tubes, use the UX-120 tube in the last stage. Easily fitted to the UV-199 socket with a Na-Ald COUPLER No. 920 Connectorald which also provides cables for attaching necessary extra 45 volts B battery To Isolating for the UX tube. and 22J volts C battery required Condenser Price, $1.25. No 24 D.S.C. Wire

How to switch to dry bat- teries without sacrificial FIG. I volume or quality The combination of a UX-120 tube for the last The first winding put on the coil form is the stage with UX-199 tubes and over at one end of the is in the other sockets pro- secondary, it, form, vides, with dry cells, re- wrapped a piece of insulating material, such as To Plate sults previously obtained only with storage bat- of teries. Fit UX-120 tube ANTENNA COUPLER to the UV-201A Socket R.F Tube with Na-Ald Connector- To Grid aid No. 120. Cables >. provided for attaching extra B and C batteries. Fit UX-199 tubes in all other sockets with Na- Ald No. 419-X Adapters. to Primary Price, No. 120 Connect- of orald, $1.25; No. 419-X No. 120 35c. Adapter, Connectorald V. Audio Transformer

1 ALDEN MANUFACTURING COMPANY Mid-tap Dept. B 17 Springfield, Mass. To Plate of All Na-Ald Sockets, Dials and Adapters are protected by patents. Many patents Pending "Detector Tube

->- ToNeutCond. FIG. 3 Ant Reflex, at its best, is a system of dual ampli- fication that must be handled with utmost Prim. consideration and, when installed properly in a receiver, offers advantages, economically and electrically, that cannot be seriously disregarded. Gnd. However, there are those who, in attempting ALDEN MFG. CO., to rid their receiver of the troubles caused by an Dept. B17. Springfield. Mass. FIG. 2 inefficient reflex system, desire to eliminate the Please send me complete information on how to reflex feature and substitute for it a increase volume and clarity in any set by the entirely use of the new tubes. paper, cambric cloth, etc. The width of this stage of straight audio frequency amplification. S Name piece is about TJ inch, and over it is wound 15 The circuit-changes necessary to make-over a Address turns of the same wire for a primary. For the four-tube receiver are few, and are shown in and In the four-tube City State interstage coupler, located between the radio Figs. 4 5. Fig. 4 regular frequency and detector tubes, the coil unit has circuit is shown. Fig. 5 shows the new circuit. RADIO BROADCAST ADVERTISER 007 The New NATIONAL EQUICYCLE Condenser

The latest development in straight line frequency con- trol as applied to NATIONAL Condenser design. Increases range of rotation from 180 to 270, permit- ting more precise adjustment and sharper separation of stations, and accomplishes this WITHOUT BD2-A Type BD1-A GEARS, CAMS, OR LEVERS. Type NATIONAL NATIONAL TUNING UNIT TUNING UNIT Embodying the genuine Embodying the genuine Browning - Drake Trans- Browning-Drake Induct- former and the NATION- ance Coil and the NA- AL Condenser TIONAL Condenser

It changes and a mob lengthens into an the line orderly of procession march!

(Patented February 10, 1925)

Tests Conducted at Harvard University, by Prof. Field, give characteristics of the new Equicycle Condenser as indicated by the following graph:

C;oO

The novel shape of the plates spaces the station groups at equal intervals of 10 oO kilocycles (as speci- fied by the U. S. De- partment of Com- merce) in a true straight frequency

Kilocycles

line. o,o O

in

Frequency

Type B NATIONAL VELVET VERNIER DIAL RADIO BROADCAST ADVERTISER

A BETTER LEAD-IN

FIG. 4

the dotted lines indicating that part of the but has not the correct size, as recommended, on Then this former circuit which was reflexed. hand. It may be observed from these two circuit It is quite a simple matter to get over this, picture will sketches that the audio transformer employed however, by the combination of a variable and a tell you why as the reflex agent is merely eliminated from its fixed condenser. you should re- position and re-located as the transformer for For example, suppose a condenser of .001 mfd. fuse anything the first straight audio amplifier. The primary is desired. By shunting the usually handy .0005 variable condenser with a fixed .0005. but an Electrad mfd. condenser, the desired capacity is obtained. Certified Lead'In. Saves marring your window or door frames. Fits under locked windows. Bends to any de- sired shape. Imitations do that too, but they stop there. Notice what else you obtain in this Electrad Lead'In. Insulation, 10 inches long, waterproofed and protected entire length. Riveted and soldered Fahne' stock clips. Sold at all good radio stores and counters. Price 40c. Canada 60c. Ask for it by name. For safety's sake refuse imitations.

FIG. 5 For of the push-pull input transformer, instead of If, with this same variable condenser, it is desired Clearer being in the plate circuit of the radio frequency to lower the total capacity in a circuit to which in series with it Purer tube, is in the plate circuit of the new audio it is applied, then a condenser stage. will produce the desired result. 1 Reception With the new circuit, where ux-i 12 tubes are In the first case the fixed condenser in parallel the minimum that can. Do This used in the push-pull amplifier, well-nigh perfect arrangement capacity of the variable reproduction will result, With the use of this be obtained with the plates Place an Electrad Audiohm across the second- type of tube, it is es- condenser completely ary of your audio-transformer. Then you will be sential that 9 volts C .0005 unmeshed will enjoy your radio. Kills distortion, elim- battery be employed greater than when only inates squeals and howls. Fits all audio trans- mfd. as a bias for the the variable condenser formers. Easy to attach. For sale at good radio grid C \\ alone is used, a ca- stores and counters. $1.50. Canada $2.10. push-pull amplifier, 2 by i to that of with 135 volts plate C - Q- pacity equal the fixed condenser potential. Jill used. If the minimum IN SERIES CONDENSERS capacity of the varia- AND PARALLEL ELECTRAD ble condenser is.oooo2^ INC. IS often the case mfd., the total mini- 428 Broadway New York that the radio man Max. .0005 mfd mum capacity of the Makers of Certified Radio 'Essentials and Accessories: two condensers is Grid Leaks, Fixed Condensers. By-Pass Condensers, ITwill require a con- Min. .000025 - Variohms, Resistances, Rheostats and Potentiometers, denser of a certain .000025 plus .0005 Jacks, Switches, etc. Write for catalog. mfd. See 6. If specified capacity when ------C ----- Fig. the condensers are ar- experimentally hook- FIG. 6 in series, as in ing up a new circuit ranged Tested and approved by RADIO BROADCAST RADIO BROADCAST ADVERTISER 699

*

radio is always top notch. What do you do to keep it so full of pep?"

KEEPING your "B" batteries full of pep, without instead of 2 Eveready No. 770's or 2 Eveready frequent renewals, is simply a matter of using the Layerbilts No. 486 looks at first glance like an right size Evereadys for your particular set with economy because of lower first cost. But in a few a "C" battery*. months the 772's will be exhausted and have to be The rule which determines the right size "B" replaced. After the same length of time the Ever- batteries to use is so simple no one can make a mis- eady No. 770's or the Eveready Layerbilts No. 486 take, and once learned it definitely settles the ques- will still be good for many more months of service. tion of "B" service and battery economy. We have prepared for your individual use a new On 1 to 3 tubes Use Eveready No. 772. booklet, "Choosing and Using the Right Radio On 4 or more tubes Use the Heavy Duty Batteries," which we will be glad to send you upon "B" Batteries, either No. 770, or the even request. This booklet also tells about the proper longer-lived Eveready battery equipment for use Layerbilt No. 486. with the new power tubes.

On all but tube sets NOTE : In addition to the increased single LEFT-JVo. 486, life which an "C" Bat- Use a "C" battery. jor 4, 5 of more Eveready tubes. $5.50. tery gives to your "B" batteries, it will add a of When following these quality reception RIGHT- Ever- unobtainable without it. 1 to 3 rules, No. 772, on eady Dry Cell and Radio "A" Bat- Manufactured guaranteed by tube sets, will last for a year tery, \V, volts. NATIONAL CARBON Co., Inc. or more, and Heavy Duties New York San Francisco on sets of 4 or more tubes, Canadian National Carbon Co., Limited Toronto, Ontario for 8 months or longer. Tuesday night means Eveready Hour 9 P. M., Eastern Standard Time, through the These life figures are following stations: established fact WEKT-New York vrsAi-Cincinnati based on the WJAR Providence WEAR Cleveland that the WKB-AofM Vfv/j-Detroit average year-round wen-Chicago use of a set is 2 hours a day. v,'Vi-Philadelphia Viac-Davmtort V!GK-Bufalo Turrn'" i Minneapolis Radio Batteries WCKZ-Pittsburgh \ St. Paul of No. Louis A pair Eveready last ~they longer Pacific Coast, Eveready Program, 772's for a 5-tube set uco-San Francisco. & to 1) P. M.

Tested and approved by RADIO BROADCAST 700 RADIO BROADCAST ADVERTISER

Fig. 7, then the minimum capacity of the cir- coil unit should have certain definite dimensions cuit is calculated by the following formula: for most efficient functioning, but it has been found that such coil units as the secondary of a transformer which has been rendered useless by a burned-out primary, or the wire-wound bobbins of discarded head phones, are satisfactory make- where Q equals the minimum capacity of the shifts for an amplifier unit. The connections variable condenser (.000025 mfd.) and C t equals for an entire receiving circuit, showing the application of an impedance or choke coil to it, The AmerTran Min. .000025 mfd. are clearly indicated in the DeLuxcis made in Max .0005 .0005 mfd. accompanying two types, a first circuit diagram. and second stage, The two units in this circuit are stand- Price, either type, tuning C 2 $10.00. C-T ard coupler units. In the antenna unit, the T-f Ci Cz secondary coil is tapped at the mid-turn for the filament return connection. Rice neutralization ^A Hew Standard ofExcellence is employed. The neutralizing condenser is con- in A (cation udioAmplif nected between the plate of the radio frequency FIG 7. tube and the lower end of the first coil-unit The realism of this new audio trans- secondary. These connections are clearly shown is Realism of the capacity of the fixed condenser, By sub- former outstanding. in the diagram. The value of the neutralizing stitution in this formula, we get: this kind results from the uniform condenser is .000016 mfd. The tuning con- densers are both about .0005 mfd. amplification of the fundamental = .000024 m fd. and resis- i The similarity between impedance tones of the lower register. The .000025 .0005 .0005 tance audio is from a AmerTran DeLuxe makes amplification apparent possible at the circuit In resistance am- The same formula may be applied for finding glance diagram. the natural of not only a resistor of reproduction the maximum capacity of the arrangement, plification approximately 100,000 the all of the trans' ohms is substituted for the and Overtones, but the maximum capacity of the variable condenser impedance coil, there is a B across the mitted Fundamental tones. being substituted for d. battery voltage drop plate resistance. Any variation in voltage causes AN IMPEDANCE-COUPLED AUDIO AMPLIFIER a corresponding voltage variation in the resistor, and these voltage variations are applied to the a means of amplifying audio fre- grid of the succeding tube, and magnified by the quencies, the impedance method is latter's action. For an impedance amplifier, the FORcommendable because of its simplicity of general action is much the same, with the ex- connection, and also because use can be made of ception that, instead of utilizing the voltage drop discarded transformers or other coils. From across a resistance, the variation in voltage the circuit in Fig. 8 it will be seen that all that across an inductance is used. It is essential that is necessary for a coupling agent between the re- the isolating condenser C, should be of the generative detector tube and the first audio tube, highest quality, one of mica dielectric being rec- is a coil an iron core. Of course, this ommended. The AmerChoke having type 854 is a choke coil or impedance 'CHOKE OR IMPEDANCE of general utility. AUDIO AMPLIFIER Price $6.00.

A Good Audio Amplifier

Requires enough plate and grid bias voltage on its tubes to prevent them from being overloaded by the signal voltage. The AmerTran PF-45 or PF-52 with the half wave high voltage rectifying tubes now available and suitable condensers and resistances together with three AmerChokes Type 854 will furnish these proper voltages. This combination will give real quality loudspeaker volume. Amer' Tran Power Transformers also sup- FIG. 8 ply A. C. filament current for the last audio tube. A GRID INQUIRY BLANK AmerTran Audio Editor, The Grid Transformers type RADIO BROADCAST AF6 (turn Ratio 5) and AF7 (turn ratio Garden City, J^eu> Yorlf 3H) are the leaders in their class. Price, DEAR SIR, either type, $5.00. I enclose a Please give me the fullest information on the attached questions. stamped envelope. Write for booklet describing these and other this information free AmerTranProducta with recommendations CH I am a subscriber to RADIO BROADCAST and therefore will receive on their use. It's free on request. All prices of charge. are F. O. B. Newark, N. J. D I am not a subscriber and enclose $1 to cover cost of answers. AMERICAN TRANSFORMER CO.

178 Emmet Street, Newark, N. J. NAME "Transformer builders for over twenty-fire years"

ADDRESS . Sold Only at Authorized AmerTran Dealers. G. A.

Tested and approved by RADIO BROADCAST RADIO BROADCAST ADVERTISER 701 RH"amm ar Ivmdl )

hinoton, D. C, ilng during the >gged in no less dozen stations, regenerative sets ruined reception. le to make out some station in Testimonials on the rlca operating at s. From results Hamtnarlund-Roberts I am sure that und-Roberts is cap- Receiver Trans-Atlantic Re- I feel that Ham- Roberts is one of i buys in radio to- Qrandview, Washinoton G. J. A. Electrical Engineer Last night I received PWX at Havana, Cuba on the loud speaker. Other sta- tions that I get regularly are : WFGB at Atlanta, Williamsport, Pa. Nashville, Georgia; WSM, We have tested the Ham- Tenn. ; WGY. Schenectady, marlund-Roberts and find it N. Y.; WSMB, New Or- to be exactly as you rec- leans. Louisiana ; C'/K, ommended. vol- Mexico City, Mexico. Surprising ume and very clear and Ready to back your set deep se- against any other of the tune, exceedingly lective, H. B. S. same size. Logged over 100 stations the first weelr R. F. l/iousandsHaveftufltlt! 10 Lansing, Mich. 2 On the first night of the Butte, Montana of assembly is an outstanding feature of the Hammarlund-Roberts Trans-Atlantic Tests, I had SIMPLICITYreceiver. Thousands of amateur builders in all of the en- PWX, Havana, Cuba, on During tests the Hammai- parts country testify the loud speaker, so loud lund-Roberts was installed thusiastically to the ease of assembling this circuit and express their delight at the that it could be heard at in the Butte Radio Club times all over s six-room Headquarters and dials set results secured by their own handiwork. house. Tor 2LO. Immediately we Have not heard of anyone were able to through get The secret of their success lies in the flawless of beating this record. I have for a few moments, long technique every part entering ten witnesses to this recep-

to hear announce- i enough into the assembling of this set. The Hammarlund-Roberts receiver the tion. J. ;. ments made in English, represents German, and Spanish. This composite achievement of ten leading engineers, backed by ten of the best known man- was followed by both in- ufacturers of radio is the of has 13 strumental and vocal music. parts. Every part work a specialist and been chosen M. R. C. because it meshes easily and yet efficiently with every other related part in the set. Morristown, Tennessee I assembled the Hammar- After you have assembled this receiver you will want your friends to call around lund-Roberts Receiver in one day's time. The set is and for themselves as a radio And will be efficient and to Wheeling, W. Va. judge your ability engineer. your pride highly up all claims made by you. justified. The Hammarlund-Roberts receiver combines remarkable volume and On January 25th, 1926, I I have owned many factory picked up 7EAJ of Madrid, sensitivity with an unusual degree of selectivity and tone quality. As for distance built sets and will say that the Hammarlund-Roberts is Spain. Reception was so have on either side enthusiastic users of the Hammarlund-Roberts loud and clear from the you testimony by superior to them all. This cone speaker. It was de- in all sections of the country. A perusal of these comments will revolutionize all set is capable of building sirable to cut the volume up tremendous volume with- to considerably. your previous ideas of five-tube performance. Should you desire verify any of out distortion and behaves like a thoroughbred. I have received CZE of these reports we will be to furnish with full name and address on request. Mexico City and PWX of glad you I get New York, Atlantic San Havana. Cuba ; both of City, Jacksonville, these stations I have re- Francisco, Montreal, Havana, ceived before these tests Cuba, and Mexico City. however. I have logged over 90 sta- tions and more are coming In all the time. N. B.C. 4iamma

Hammarlund-Roberts 1182-A Broadway, New York City

SEND FOR THIS BOOK

Contains step-by-step In- structions on the assem- DURHAM bly, wiring and operation. This famous instru- of the Hammarlund-Rob- ment and other parts RESISTORS UNION erts. Fully illustrated ; shown here are some PHONE TIP most complete "How to ever of the quality units Build It" radio book JACKS published. 25c. in the Hammarlund- DIALS and SOCKETS Roberts. RHEOSTATS

Tested and approved by RADIO BROADCAST 702 RADIO BROADCAST ADVERTISER

Sent/ for this : Now, I HAVE FOUND * . <

A Department for the Exchange of Ideas and Sugges- tions of Value to the Radio Constructor and Operator

(CONTRIBUTIONS to this department are welcome and those used will be ^ paid for at the usual rates, that is, from two to ten dollars each. A pri{e of twenty-five dollars is given for the best idea used during each three-month period. The prizewinner for the last period was announced in the February RADIO BROADCAST. Manuscripts intended for this department should not ex- ceed about three hundred words in length, and should be typewritten. Little con- sideration can be given to manuscripts not typewritten. Envelopes should be addressed to this department, RADIO BROADCAST, Garden City, New York.

BETTER REPRODUCTION IN CONE HOW TO PROVIDE A COUN- The outstanding receiver develop- ment of the season, in which is SPEAKERS TERPOISE SYSTEM combined the genius of two of the EASY to eliminate the who use the Roberts or most distinguished radio engineers. way jingle in the notes and circuits and are A receiver for the home builder high reproduce Browning-Drake Al the bass notes more in a THOSEtroubled with broad antenna that will represent for several faithfully tuning cone loud as an well use the induct- seasons to come a far speaker, taking example couplers, might single the Western Electric No. 540 AW, is as ance with a conductively coupled antenna, greater value than any follows: the antenna about one third up other design available. placing tap Loosen the set screw in front which holds Several outstanding fea- the pin, then remove the screws in the back tures place the design in thus allowing the metal ring, fibre ring, and a far in advance position screen to be removed. of anything available or This exposes the telephone unit held to contemplated. Unlimited wavelength range, the frame by three screws. First, mark with interchangeable antenna and detector the frame where the unit is held to it so coils; marvelously improved audio trans- that it can be put back in the same place, formers; a special self-contained wiring and then remove the screws and carefully but one or station selector harness; tuning lift out the unit. control, are special features. Remove the screw holding the pin to Over-all design is rugged and solid. Adapt- its support and insert a piece of electric tape standard ed to practically any cabinet, any between these two members, first making standard or eliminator tube, any battery a hole through the tape for the screw to source of outdoor antenna or loop. supply, go through. Replace the screw. from the filament end of the inductance, a screw driver and pair of pliers nec- Only Then slip over the pin a rubber tube 5 and grounding the negative A battery line. set can be built at an ex- essary. The inch or more in thickness reaching from For those who have the space or who live low cost and are tremely parts readily the base of the pin to just short of the parch- in shingled houses, the substitution of a at all radio dealers. available ment, and having its bore slightly smaller counterpoise for a ground (entirely elimi- than that of the so as to grip it tightly. nating the ground will materially sharpen Manufacturers: pin, 'Represented With the use of this system, the possibility the tuning and in my case was found to Belden Co.S-C Harness Mfg. Wiring of bending or otherwise injuring the pin by produce much clearer signals, with greater Central Radio Laboratories Centralab loading it with rubber tape is avoided. intensity, than with the ground. The Resistance See Fig. i. lower edge of the shingles generally stops about 3 feet from the ground and overhangs Corporation Fixed Con- Polymet Mfg. the foundation wall by several inches. densers, Leak, and Leak Clips Cone Small insulated screw eyes placed under Poster & Co. Drilled and Processed the shingle-overhang all the way around Front Panel and Drilled Sub-Panel the house will hold a good counterpoise. /Angle If the all the to the Silver-Marshall, Inc. Variable Con- Rubber covering shingles go way ground, a row of screw about the of the densers, Coil Sockets, Coils, Tube eyes height will work almost as See Sockets, Vernier Dial, Mounting doorways good. Brackets Fig. 2. My antenna combination is now an 80- Thordarson Elec. Co. 200 -Tape Cushion Mfg. foot antenna and a loo-foot counterpoise. Power Transformers J. B. GREENMAN, Yaxley Mfg. Co. Rheostat, Jacks, Montclair, New Jersey. Switch FIG. I SOME NOTES ON SILVER'S MODEL Get the hand-book at your radio dealer's, 1926 RECEIVER WITH CHOKE or clip the coupon and send 25 cents to Re-assemble, taking care to have the pin AMPLIFICATION S-C MERCHANDISING straight and to put the telephone unit back in the same place on the frame as on the theme of COMPANY marked. Tighten the screw in front to McMurdo Silver's "Model 1926 the VARIATIONSBroadcast Receiver," introduced 65 E. Jackson Blvd. Chicago pin. Before replacing the screen, tune in on to its readers in the November, 1925, some good station and test out the speaker. number of RADIO BROADCAST, were pre- S-C Merchandising Company If there is any jingle leave the set screw in sented by E. R. Pfaff in the January, front secured to the loosen the number. Before the appearance of 65 E. Jackson Blvd., Chicago pin, up 1926, screws holding the telephone unit to the the latter article, the writer had con- Herewith find cents for which please 25 frame, and move the unit until the jingle structed a receiver of this type using send the hand-book of the new S-C me disappears and the best reproduction is Thordarson Autoformer audio amplifica- Four-Tube Receiver obtained. Then tighten up the screws. tion. As the set was constructed for Replace the screen and rings, thoroughly experimental purposes, and this circuit is Name . . tightening up all screws. peculiarly adapted to this end, one or two WILLIAM C. MORRILL, E. E. wrinkles used may be of interest. Address New York. As described, the set has no binding

it Tested and aonroved bv RADIO BROADCAST -A RADIO BROADCAST ADVERTISER 703 aradofi

ECTROSTA1IC CONDENSERS

19 YEARS OF SPECIALIZATION IN THE RADIO FIELD

are behind each Condenser Trade Marked

TYPE I TERMINALS For Soldered Connections in Any Portion of Circuit * In Radio Receiving Sets The Biggest Little Things Are The FIXED CONDENSERS

The MODEL T FARADON is furnished in all usual TYPE II TERMINALS sizes to meet the requirements of Quality Performance. Holds Standard Cartridge Grid Leak- Also Takes Soldered Connections

Quotations covering quantity requirements furnished to SET MANUFACTURERS

promptly upon request.

Some Important FARADON Users: U. S. Army General Electric Co. TYPE III TERMINALS U. S. Navy Radio Corp. of America For Transformer or Other Binding U. S. Signal Corps Western Electric Company Post Mounting U. S. Bureau of Standards Radio Tel. Co. Also Takes Soldered Connections Tropical Westinghouse Electric 85 Mfg. Co. WIRELESS SPECIALTY APPARATUS COMPANY JAMAICA PLAIN BOSTON, MASS.

if Tested and approved by RADIO BROADCAST Vk" 704 RADIO BROADCAST ADVERTISER

posts, the ends of a Belden battery cord being attached directly to various terminals, transformer, switch, etc., in the set. For experimental purposes, it is handier to use binding posts, however. Choke amplifica- tion may be used with either 90 or 120-135 volts of B battery. In case 90 volts of B battery is used, the 90 volts go to both r.f. and a.f. amplifiers, while the detector re- ceives 45 volts. If, however, it is desired

Seven Years of Superiority

as the original HI-MU tubes KNOWNbefore the of To coils & To To TO TOA.F. days BCL; Condensers Switch Rheostat A.F. Resistances Preferred by amateurs and experts be' FIG. 3 fore the first popular receiving set was sold; Progressively improved in construction to employ 120-135 volts of B battery and performance; on the last audio stage, then the r.f. am- Made in the newest and best equipped plifier and the first two stages of audio in America. plant receive 90 volts. There are three separate Get the World on Your Dial units to be provided for, the r.f., ist and With Myers Tubes 2nd a.f. amplifiers, the detector, and the last a.f. amplifier stage. If three B Low impedance, high amplification constant, high plus are one for each mutual conductance. Best results in any circuit binding posts used, unit, impedance, resistance or transformer coupled. the a.f., r.f., or the detector may be quickly connected at the to facilitate cAt Your 'Dealer's binding posts the use of various values of B Myers Radio Tube Corporation potential Cleveland, Ohio without tearing the set apart. The RADIO BROADCAST Attractive, compact, correct December, 1926, inside and out, no clumsy contained two very interesting articles materials. Made by pioneer on the use of tubes, one Keith designers and builders of high-mu by Radio Tubes. Henney and the other by Glenn H. Brown- ing. The latter describes the use of Daven

PUT wood Mandrel with ISspokes

Bushings with Marvelous / set screws > Clarity and Distance .' HDia. Rod Use Myers Tubes VM in any set and get -- - better results in vol- 2 ume, tone, range pr-ea and ease of control. Made with stand- ard four prong base, or double - end, in types Myers 01 A, Myers 01 X, My- ers 99, Myers 99 X.

List Price

Type 01 $2.00 Type 99 2.25

At Your Dealers

SEND FOR New No. 739 Circular describing special voltmeters for Radiola, Victor and Brunswick sets Order from Dealer j^

Jewell Electrical Instrument Co. 1650 Walnut St. - Chicago "26 Years Making Good Instruments" RADIO BROADCAST ADVERTISER 705

This is Station 2-L.O. London, 12 Midnight

listeners-in on this side of the At- WHENlantic first heard the voice of the British announcer, and then a program of music from the famous Savoy in London, they experienced one of the real thrills of radio.

To get everything that is on the air the faint sig- nals as well as the strong ones effective insulation of all radio parts is a prime essential. The best way to make sure that a radio set or parts are well insulated, is to buy those in which Bakelite is used.

Bakelite is used by 95% of radio set and parts manufacturers. It is the standard material for front and base panels, dials, knobs, tube sockets and bases, fixed and variable condensers, rheostats, plugs and other radio accessories and parts. Write us for a copy of Booklet No. 29, "Bakelite in Radio" it's a helpful guide in buying radio equipment.

BAKELITE CORPORATION 247 Park Avenue, New York, N. Y. Chicago Office: 636 West 22nd St. BAKELITE CORPORATION of CANADA, Ltd. 163 Dufferin Street, Toronto, Ontario, Canada.

REGISTERED PAT. OFF. BAKEj f^ \ U_._S.LIT THE MATERIAL OF A THOUSAND USES "The registered Trade Mark and Symbol shown above may be used only on products made from materials manufactured Bakelite by Corporation. Under the capital "B" is the numerical sign for infinity, or unlimited, It the quantity symbolizes infinite number of present and future uses of Bakelite Corporation's products."

^ Tested and approved bv RADIO BROADCAST ^ 706 RADIO BROADCAST ADVERTISER

the counter disk is correct for a two-inch 1. Disconnect battery from charger. disk. By means of the screw on the crank, 2. Disconnect charger from mains. and the counter, each turn of the crank 3. Connect battery to receiver. screw machine registers one complete turn of the coil. To eliminate the clumsy connection and It is easier to use two rings of heavy card- removal of clips, the author has devised board tubing of given diameter and half a simple arrangement whereby the com- an inch in width, clamped on each side of plete process of connection necessary to products the spokes with two pieces of heavy sheet the proper charge and discharge of the metal, than to make various size wood baitery is controlled merely by the move- mandrels. In this way, one mandrel ment of a double-throw switch. serves for all diameter coils. Take care to The switching device is illustrated in the center these on the form before The di- brass properly accompanying diagram, Fig. 7. winding. An excellent coil can be wound mensions of the switch itself are unim- in this way. These coils give fine results portant, so long as the extra contact which in a RADIO BROADCAST "Knockout" connects the charger to the line supply is receiver. made large enough so that the switch MATERIAL REQUIRED blades connected to the battery are en- tirely clear of their contacts before the i x metal rod for shaft 45-inch j-inch line supply is cut off. (60 penny spike will do), BERNARD SALZBERG, i Piece of hard wood wide and of For plugs, jacks, clips, f-inch New York City. diameter desired,

i Piece of hard wood inches x i inches condenser and trans- 5 j ECONOMICAL SUB-PANEL (support for shaft), BRACKETS i Piece of heavy sheet metal 3 inches x former etc., inches for crank. parts, f suddenly faced with the neces- x A-inch for 15 21-inch spikes spokes sity of making a pair of brackets BRASS assures econo- heads cut (with off). BEINGfor a sub-panel, I tried the following: 2 Pieces of brass bushing, j-inch inside Get from a good hardware or plumbing in with set my quantity pro- diameter, j-inch wide, supply store, a piece of i*s-inch channel screws. brass, |-inch wide. This will be shaped as i Baseboard about 15 x 8 x f inches. duction. It also gives shown in i, Fig. 8. i Small wood disk about 2 inches Measure how far the bracket must pro- diameter thick for counter, the electrical j-inch ject back from the front panel and add right with some small nails to fishing go about two inches for support to fasten around and the periphery. on to the front panel. At the point where conductivity 2 Wood of same size spools (thread you wish to bend the strip make a cut, spools.) perpendicular and square across, with a mechanical 2 Pieces of threaded rod 2 inches accuracy A long. hack saw, merely cutting through the side 2 Pieces of brass or wood tubing (pipe walls as illustrated in 2, Fig. 8. to inch than essential proper op- stems) | longer spools. Then, with a three-cornered file, widen 2 Pieces of metal x inches wide strip 4 f the saw cut to a "V" shaped notch, as in eration of radio sets to hold spools. R. S. HART, and parts. Pisgah, Kentucky. A HANDY BATTERY THROW-OVER SWITCH

a recti- vibrating "magnetic " fier, such as the Homcharger, WHENis employed to charge the storage battery, it is necessary to observe the fol- lowing procedure: To charge: COPPERS BRASS 1. Disconnect battery from receiver. 2. Connect charger to line supply RESEARCH ASSOCIATION (no volts a.c., 60 cycles). 3. Connect battery to charger. FIG. 8 25 Broadway, New York To discharge: 3. Be sure the angle at the bottom of the notch is one of 90 and that it is pretty accurately placed 45 on each side of the perpendicular. The bracket is now bent, as shown in 4. If your angle is correct, the top piece will project from the panel ; exactly square, and the weight on the sub- STATIC will be the side panel supported nicely by Without Loss of Volume walls of the notch as they come together. STATIC Of course, by regulating the angle of the ELIMINATE filed notch, make a bracket that weather you may Enjoy perfect reception regardless of of conditions. The Static Eliminator the newest projects from the panel at any angle in Radio cuts out and most startling thins more or less than as wish. This practically all static without loss of volume! 90 you And in addition it will help increase selec- idea could be used in making sets with a tivity, tune out local stations, sharpen signals, remove noises, lessen interference, and prevent sloping panel. re -radiation ! fill Use It with any receiving set simply hook To finish the bracket, the corner up according to our simple instructions and en- where the brass was with solder. joy perfect reception bent, unmarred by static. This the bracket from bending Satisfaction abso- prevents lutely guaranteed back under pressure from beneath, such - back if Elim- ^*KI Money foot on the sub- ^j7 inator is returned as is exerted when the _ ^Jl within 5 days. rests on a table or the bottom of the Miil your order Today. panel cabinet.

! : LMl*. I!/: R. L. DOUGLAS, 627 United Bank BldiCincinnati.O. FIG. 7 Huntington Park, California. Tested and approved by RADIO BROADCAST RADIO BROADCAST ADVERTISER 707

ATWATER KENT RAD I

Are you running a store or a museum?"

what the caustic stranger cial value ? Is it a good product, nation- said to the THAT'S radio merchant. ally advertised, and fairly priced? Has it a record of consistent sales and as- The merchant started to flare up, surance of Does it sell but thought better of it. Instead, when permanence? and to the visitor departed he spent a profit- easily stay sold, enabling you often with a minimum able half-hour with his own thoughts. turnyour capital of overhead? In is Had he taken on too many lines? short, '^.profitable Had he selected them indiscrimi- over a period of time? If is month for mental nately? Didn't unsalable reminders April your clutter his shelves? Obsolete models, stock taking for figuring what you discontinued by the manufacturer in have been doing, where you stand and whither are bound isn't this a the middle of the year? Orphan sets you to look see what the maker gone out of business? good time around, Atwater Kent Radio merchants have Those job lots he had bought to done and what think of the radio "move quickly" weren't they still they business? hanging around? Yes, and good sets, would fit into the but without the necessary advertising Perhaps you pic- too. to make people want them? And sets ture, EVERY SUNDAY EVENING that looked good but ate their heads offin service calls? Sets t^at had come The Atwater Kent Radio Hour brings you the stars of and in Radio's finest Hear in with drums and opera concert, program. beating stayed it at 9:15 Eastern Time, 8:15 Central Time, through: while the on? parade passed WEAF New York WFI 1. ... Philadelphia Providence woo / "It is a museum," said the merchant. WJAR alternating WEEI Boston WCAE Pittsburgh "I only thought it was a store." Where- WSAI Cincinnati WGR Bu/alo upon he cleared out the relics as best WCAP Washington woe Davenport wcco . . . Minn.-Sl. Paul WTAG Worcester he could, concentrated on two lines WEAR Cleveland KSD St. Louis WLIB Chicago wwj Detroit his customers really wanted, and lived Kent Radio. happily ever after. Write for illustrated bookjet of Ativater * * * ATWATER KENT MANUFACTURING CO. A. At-wattr Kent, President Has the Radioyou handle commer- 4726 WISSAHICKON AVENUE, PHILADELPHIA, PA. *

Tested and approved by RADIO BROADCAST if 708 RADIO BROADCAST ADVERTISER Short-Wave Stations of the World

'"THIS list, containing more than a hundred short-wave stations situated throughout the world, is * FROST-RADIO about the most accurate one to be The Traffic of the Radio completely yet printed. Department No. 530 Socket Corporation of America cooperated in its compilation. Included in this list are stations known to be operating on the wavelengths given, stations licensed for operation, and stations which have been in all new tubes for type operation to any considerable extent during the past year, and which are not definitely discontinued. The new No. 530 FROST-RADIO Socket takes ALL of the new type tubes. It CALL FREQUENCY WAVELENGTH is made from black polished Bakelite, SIGNAL IN KC. METERS and has sturdy contact springs which hold the tube prongs for almost their POP Nauen, Germany .... 22209 13.5 2XS Rocky Point, New York . . . 20082 14.93 entire length. Price 40c at your near- 2XAW Schenectady, New York . 19988 15 est dealers. 2BR Chelmsford, England 19988 15 POP Nauen, Germany IST.'iS 16 NKF Anacostia, District of Columbia 18738 16 2BR Chelmsford, England 17 POP Nauen, Germany .... 16657 18 2XAD Schenectady, New York . 14991 20 KFVM SS Iilalia 14991 20 POP Nauen, Germany .... 14991 20 NAL Washington, District of Columbia 14991 20 NEPQ USS Relief .... 14991 20 NKF Anacostia, District of Columbia . 14414 20.8 WIK New Brunswick, New Jersey . 13628 22 2 YT Poldhu, England 11993 25 POY Nauen, Germany .... 11993 25 FW Sainte Assise, France 11993 25

NKF Anacostia, District of Columbia . 11758 25.5 AGA Nauen, Germany 11532 26 PCMM Kootwijck, Holland .... 10903 27.5 POW Nauen, Germany .... 10708 28 2X1 New York . 9994 30 The No. 630 is a rich-looking socket because it is Schenectady, made from real Bakelite. Takes all the new typ NAL Washington, District of Columbia 9798 30.6 tubes. Price 0o 2YT Poldhu, England 9369 32 ANE Malabar, Java 9369 32 NAJ Great Lakes, Illinois .... 8630 34 WQO Rocky Point, New York . . . 8560 35.03 PCMM Kootwjjck, Holland .... 8328 36 PCUU Kootwijck, Holland .... 7890 38 KFVM SS Idalia 7496 40 NAS Pensacola, Florida .... 7496 40 NAJ Great Lakes, Illinois .... 7496 40 NPG San Francisco, California . . . 7496 40 NRRL USS Seattle 7496 40 NOW USS New Mexico 7496 40 2XAC Schenectady, New York . 7496 40

NKF Anacostia, District of Columbia . 7260 41.3 2XAF WG Y Schenectady .... 7160 41.88 5XH New Orleans, Louisiana. . 7139 42 FW Sainte Assise, France 7139 42 WIZ New Brunswick, New Jersey. 6970 43.02 WQO Rocky Point, New York . 6814 44 KZA Los Angeles, California . 6814 44 KZB Los Angeles, California . 68!4 44 Holland 6518 as revealed this PCLL Kootwijck, .... 46 Note the spring construction by 6119 49 cut-away view. These sturdy springs are held be- WHO Sharon, Pennsylvania tween cast bosses, and stay put. NPM Honolulu, Territory of Hawaii 6119 49 2XAD Schenectady, New,York . 5996 50 SAJ Karlsborg, Sweden .... 5996 50 WQN Rocky Point, New York . 5822 51.5 NPU Tutuila, Samoa 5657 53 NBA Balboa, Canal Zone .... 5552 54 NKF Anacostia, District of Columbia. 5511 54.4 WQN Rocky Point, New York . 5501 54.5 KFKX Hastings, Nebraska .... 5354 56 ANF Malabar, Java 5354 56 1 XAO Belfast, Maine 5354 56 WQN Rocky Point, New York . . . 5260 57 KDKA East Pittsburg, Pennsylvania 5100 58.79 KDC Casper, Wyoming .... 5082 59 When the tube is inserted each prong is gripped 2YT Poldhu, England 4997 60 vice- the full length on two sides and held in a KDKA East Pittsburgh, Pennsylvania . 4759 63 like grip. Dirt cannot remain on the or springs 8XS East Pittsburgh, Pennsylvania . 4475 67 here. prongs NPO Cavite, Philippine Islands 4409 68 WRB Miami, Florida 4383 68.4 HERBERT H. FROST, Inc. WRP Miami, Florida 4383 68.4 314-324 WEST SUPERIOR ST., CHICAGO 2 XAO Belfast, Maine 4283 70 New York City Cleveland Kansas City POX Nauen, Germany .... 4283 70 Los Angeles NPO Cavite, Philippine Islands 4283 70 (4283 (70 to USS Los Export Office: 314 W. Superior St., Chicago NERM Angeles (3548 184.5 NQG San Diego, California . . . . 4253 70.5 NKF Anacostia, District of Columbia. 4205 71.3 NPL San Diego, California 4182 71.7 WIR New Brunswick, New Jersey. 4052 74 SFR Paris, France 3998 75 NUQB USS Pope 3998 75 Blackburn Ground Clamps NIRX USS Canopus 3998 75 Illinois . 3945 76 Telephone companies using NAJ Great Lakes, 3874 77.4 MILLIONS. fits NFV Quantico, Virginia Adjustable J1AA 3795 79 any size pipe. Requires no pipe Iwatsuki, Japan screw bores KFVM SSJdalia 3748 80 cleaning through 80 rust and scale. Send 12 cents NEL Lakehurst, New Jersey 3748 New York . 3748 80 for sample and postage. 2XK Schenectady, NPG San Francisco, California 3701 81 Blackburn Specialty Company NKF! District of Columbia . 3679 81.5 1960 E. 66th St. O. Anacostia, Cleveland, ROW Moscow, Russia ... 3612 83 NKF Anacostia, District of Columbia. 3569 84 SFR Paris, France 3527 85 NQG San Diego. California 3486 86 KIO Kahuku, Territory Hawaii 3331 90 2 YT Poldhu, England 3190 94 OTtXS KEL Bolinas. California . . . . 3156 95 8XS East Pittsburgh, Pennsylvania . 3123 96 PERFECT REPRODUCER POX Nauen, Germany 2998 100 NAM Norfolk, Virginia 2998 100 103 Loud, Pleasing tone. Handsome WGH Tuckerton, New Jersey . 2911 material. Distinctive design. WHU SS Big Bill 2855 105 109 2XK Schenectady, New York . 2751 $22.50 to $30.00 Horns, SS Eloise 2726 110 10.00 to 12.00 KFVT Units, KFHV SS Facile 2726 110 KFWJ SS Gallavant 2726 110 1 XAO Belfast. Maine 2677 112 American fflectric FL Paris, France 2607 115 COMPANV KFWK SS Nirvana 2607 115 State & 04th Sts. Clih-aeo KFVB SS Bridget 2600 115.3

Tested and approved by RADIO BROADCAST RADIO BROADCAST ADVERTISER 709 C

III Jfrtenb* JJete :fate* are far more dependable than strangers.

The logical plate shape of a rotary variable condenser is semicircular, and to use these plates to the proper advantage, neither rotor nor stator should be cut away to any extent. Cardwell Taper Plate Type"E" condensers have the old familiar plate shape, but have a straight frequency tuning characteristic.

Authorities agree tfyat these condensers are the finest instruments ever produced. Mr. Arthur H. Lynch, Editor of "Radio Broadcast," selected them as ideal for use in the "Aristocrat" and other receivers. tTljr Cnpcr JDlatc Mr. Gerald M. Best, Editor of "Radio," tEppe "IE" uses them in his new "Super."

toi t f i st rni t (jfi {requenc;) The Type "C" approaches straight "C" 6a a tuning tljarattertetiti frequency at minimum but gives more separation at maximum. ntnbifteb strattjlit toabe

They are priced the same the .0005 mfd. lengtf) tuning tu'rbe capacity lists at $5.00, and others, pro- portionately.

lje alien 23. CarbtoeU #Ug. Corp. 81 PROSPECT STREET BROOKLYN, N. Y.

Sc. in stamps If your dealer can't brings this supply you, order booklet on the direct. Write for Best Super- illustrated catalogue Heterodyne. and handbook.

C it to t if $ t f "THE STANDARD OF COMPARISON" 710 RADIO BROADCAST ADVERTISER A KEY TO RECENT RADIO ARTICLES By E. G. SHAULKHAUSER

is the sixth installment of references to THISarticles which have appeared recently in var- PARTS ious radio periodicals. Each separate reference should be cut out and pasted on cards for filing, or pasted in a scrap book either alphabetically or numerically. An outline of the Dewey Decimal System (employed here) appeared in the November and January RADIO BROADCAST, and will be reprinted in an early number.

Rii3.4. IONI7AT10N; HEAVISIDE LAYER HEAVISIDE THE S C Popular Radio. Jan. 1926, pp. 61-63. LAYER. "Up and Down Movement of the Heaviside Layer." Dr E.E. Free. A short outline covering the research in high frequencies RECEIVER carried on at the Research Naval Type 316 Condenser, Laboratory by Dr. A. H. Taylor and Dr. E. O. is Most of the .00035 Mfd. for single Hulburt, reported. In this new, single control, all-wave, 4-tube receiver, or gang control. Brass phenomena observed are explained on the basis of the Heavi- side Layer movements. distances and plates, die cast frame. Skipped fading appar- ently the of this and its designed by eight eminent, engineering staffs, SM Price, $5.75. depend upon height Jayer position during day and night. PARTS were used wherever possible. Their unques- tionable excellence and made SM Parts R38z. INDUCTORS. INDUCTION dependability Popular Radio. Jan. 1926, pp. 80 83. COILS. the logical selection for this advanced receiver. That "Some Methods for Determining the Distributed Capacity of Coils," H. S. Knowles. is why in almost every successful receiver design of A discussion covering several methods which may be used in the and seasons will find SM Products measuring distributed capacity of coils, is presented. past present you Mathematics and graphs are used in giving the information. depended upon, and dependable. R38z. INDUCTORS. INDUCTION RADIO BROADCAST. Feb. 1926, pp. 436-438 COILS. "Design of Radio Inductances," W. W. Harper. Inductances, whose efficiency is high, must be designed to "SIX" have a low resistance to THE high inductance, frequency compared twenty-five or more microhenries per ohm being considered a Type 600 KIT Includes all parts necessary $53.00 good coil in the opinion of the writer. Such a coil results in when combined with al- 610 KIT Essentials 3 sharp tuning good condensers, Type only, including condensers, though action of coils and of Type 801 Universal pick-up crowding apparatus 3 inductances and 3 inductance sockets $27.75 in sets may make tuning broad. The standards of coil Vernier Dial, Ratio design are given as follows: (i) Low resistance over the 14.5:1. Fits any broadcast combined with as a value standard condenser frequency spectrum high THORDARSON of inductance as is permissible under the circuit conditions: right or left, 180 or (2) Effective confinement of electrostatic and electromagnetic SM RAYTHEON B-ELIMINATOR 360 movement. Price, field: (3) Consistent mechanical and electrical characteristics: $2.50. (4) Small physical dimensions so as to permit compact con- The SM Type 650 Kit includes Thordarson Transformer, Choke, struction. Experiments and tests have shown that space- wound solenoids Tube Condensers, genuine Ratheon Tube, Bradleyohms and are best for radio frequency purposes. With proper copper shielding and grooved space winding, the new all necessary parts $34 so-called Metaloid coil was designed and built. Its L/R value (5320/9.5, equal to 33, as given in the data. This Eliminator will deliver from 20 to 200 volts at three different adjustable voltages with maximum current of 50 milliamperes R343. ELECTRON TUBE RECEIVING SETS. RECEIVERS, RADIO BROADCAST. Feb. Crimes more than enough for the largest receiver. Send for Assembly 1926, pp. 430-444 Reflex "How to Build a Grimes Inverse Duplex," F. J. Fox. Instructions Silver by McMurdo lOc Constructional details of a four-tube Grimes Inverse Duplex receiver are The set is considered sensitive SEE given. very SM PARTS AT YOUR DEALERS OR SEND FOR CIRCULARS and selective, and is easily built by the home constructor. Photographs, circuit diagrams, details of coil construction, panel layout, and method of locating audio, radio, or overload howl, which might be found in the completed re- Silver-Marshall, Inc* ceiver, give the necessary information desired when building Interchangeable Coils such a receiver. for any wavelength. 103 S. Wabash Standard Sizes. $2.50. R8oo (621.353) BATTERIES, PRIMARY. BATTERIES, Ave., Chicago RADIO Type 515 Coil Socket, BROADCAST. Feb. 1926, pp. 452-455. Life of B. Will B Batteries G. C. Furness. $1.00. "How Long My Last?", A discussion on the life of B batteries in all sets from one to eight tubes or more, leads the author to the conclusion that the life of B batteries depends entirely upon current drain and size of cells in the battery. Charts and figures are verified how a definite 340 Com- presented, experimentally, showing Type time limit of or twelve months can be set on the pensating Con- Type 510 All- six, eight, average life of B batteries when these are chosen properly denser, .000025 Bakelite Socket Mfd. with for UX Tubes, for the receiver in question. 50c. knob, $1.50. Rl3l. Characteristic Curves; General Properties. VACUUM TUBES. RADIO BROADCAST. Feb. Characteristics. " 1926, pp. 456-461. How to Use Vacuum Tubes," Keith Henney. In this article, the elementary principles of vacuum tubes and their characteristics are discussed, a clear meaning of such to Radio Broadcast? the or two Why not subscribe By year only $4.00; years, $6.00, saving terms as amplification constant, mutual conductance, plate of tube characteristics in general, etc; being $2.40. Send direct to Doubleday, Page & Company, Garden City, New York. impedance, included. Data covering a great many makes and varieties of tubes are presented. Circuit diagrams show how this information was obtained. The proper use of C batteries and correct amount of fi'ament current, are essential in good tube operation, according to the author.

R62o.o68. TESTING. TESTS OF RADIO BROADCAST. Feb. BROADCASTING 1926, pp. 462-464 " "The 1926 International Radio Broadcasting Tests, W. K. Wing.

An outline of the plans and the transmitting schedule for the 1926 International Radio Broadcasting Tests are given. their full and IfammarlundP FIE C /S / O A/ Many foreign stations |ent cooperation support ^ to the success of this RADIO undertaking sponsored by BROADCAST.

PRODUCTS Raio. FREQUENCY; WAVELENGTH. FREQUENCY TO RADIO BROADCAST. Feb 1926, pp 471-472 WAVELENGTH. Write for Descriptive Literature "Taking the Complexity Out of Wavelength-Frequency Conversion," H. S. Davis. HAMMARLUND MANUFACTURING CO. A simple full-page frequency-wavelength conversion chart is presented together with information on how to use it. The 424-438 West 33rd Street New York City author emphasizes the fact that the term frequency and not wavelength is the proper term to use, and gives definite reasons.

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R343. ELECTRON TUBE RECEIVING SETS. KKHVERS. QST. Jan. 1926, pp. 17-20. Reflex. "A New Reflex Circuit", L. W. Hairy. A reflex circuit using good high primary-impedance audio transformers and proper bypass condensers, is described. Distortion is prevented also by reflexing through a radio frequency tube with a shunt rather than a series audio fre- quency connection. The method and circuit arrangement in a two- and three-tube set are discussed in some detail.

R344-3 TRANSMITTING SETS. TRANSMITTERS. 21-25. Crystal Controlled QST." Jan. 1926, pp. Practical Crystal Controlled Transmitters' . A description of crystal controlled transmitters operating from a d.c. as well as a. c. source of supply is submitted Complete constructional details of the crystal controlling station at 4 XE are given. It operates from a d.c. sourceusingan ux-2io and three 2O4-A tubes. The a. c. crystal controlled set described operates, with two ux- 210 and two 2O3-A tubes. Method of mounting the crystals and certain precaution^ are necessary in handling them, according to the author.

R402. SHORT WAVES SHORT-WAVE QST, Jan. 1926, p. 28. TRANSMITTERS. "Getting |")own Below Five Meters", H. Lyman. Several circuit diagrams with constants of transmitters suitable for the very high frequency bands used by amateurs, are given. itsinthcTube Rooy. REGULATIONS CONFERENCE, QST. Jan. 1926, pp. 33-16. Fourth National. "The Fourth National Radio Conference", K. B. Warner. A survey of the transactions and recommendations made by the various committees at the Fourth National Radio Con- A set is no better than its tubes. ference, is given. Several changes in the allocation of fre- receiving quencies were proposed, including amateur phone operation on the 3500-3600 kc band (8^.7-83.3 meters). Broadcasting With other parts and connections right a set may be conditions are to be placed on a higher plane than heretofore, through elimination of some of the stations and adoption of as good as its tubes no set can be better. new regulations govering their operation. The new frequency assignments from 550 kilocycles up (545 meters down) are also published in this summary. That's why you want CECO Tubes. They stand up R6io. EQUIPMENT; STATION DESCRIPTION. STATIONS, at its maxi- i. and deliver. With them your set works Radio. Jan 1926, pp. 10-1 Portable. "The Radio Detective". life mum. Clarity of tone, rich volume, long CECO A car, completely equipped with necessary transmitter and receivers for use in connection with the radio supervisor's work has them all to a superlative degree. in the 8th district, is described and illustrated. A Kolster direction finder, short- and long-wave receivers of various and for laboratories types, a 50-watt transmitter, equipment giving Our charted tests (results confirmed by license examinations anywhere, make this portable radio SU- station a modern radio supervisor's office on wheels. The of national reputation) PROVE CECO TUBE diagram of the field strength measuring set is shown, and constants of the circuit PERIORITY whether used as detectors, audio or given. R343- ELECTRON TUBE RECEIVING SETS. RECEIVER. radio frequency amplifiers. Radio. Jan. 1926, pp. i2ff. LC Modified "An Exceptional Four-Tube Receiver", E. E. Turner. Tubes make a Good Receiver BETTER. A four tube receiver, r. f. stage, regenerative detector, and CECO Try two stages of audio amplification, is described. The wiring and them for results. diagram shows several unique features, which are also taken them you'll BUY always up in the general discussion. Among these is the method of controlling oscillations in the regenerative circuit. Data Now ! CECO Tubes with new on coil construction and panel layout, serve as a guide to Ready type Long building the set. An ABC eliminator may be used with the set. PRONG BASES. Power Tubes, E the wiring diagram of the complete circuit being shown. Also, Amplifier This set is a modification of the LC circuit described in the (Dry Cell Type), F (Storage Battery), for last stage October, 1025, issue of Radio. of Audio R53I.2. STATION CALL LETTERS STATIONS, Frequency. Radio. Jan. 1926, p. 22. Short-wave. "Short-Wave Stations". Dealers write giving jobber's name. A complete list of short-wave stations both, limited com- mercial and general public, operating in the United States, is given. There are forty-six in all. The inclusion of class, C. E. Inc. frequency, wavelength, owner, power, and call, makes this Mfg. Co., table a most complete reference guide. R3y6.3 LOUD SPEAKING REPRODUCERS. LOUD SPEAKERS, 702 R. I. Hornless. Eddy Street, Providence, Radio. Jan. 1926, pp. 24ff. "Hornless Types of Loud Speakers", Dr. J. P. Minton. The author enters into a detailed discussion concerning the general types of loud speakers now used. The new cone type speakers make use of large vibrating surfaces. Flat surfaces may be used to obtain good sound vibrations over a large frequency range, but shaping such surfaces into the form of a cone gives greater rigidity and less natural resonance, at the same time rendering also better acoustic radiation. Three types of driving units jhave been employed in the commercial cone speakers; electro-dynamic, balanced arma- ture, and bipolar unit. These are discussed in detail.

R383. RESISTORS. RESISTORS, Radio. Jan. 1926, pp. ijft. Vacuum Tube.

"Vacuum Tube Resistors",, G. F. Lampkin. Vacuum tubes, in addition to being used as detectors, amplifiers, and oscillators, may be used as variable resistors RADIO PANELS To Roberts Knockout Fans to very good advantage. As such they have several advan- OF GENUINE BAKELITE tages not found in grid leaks or regular resistances. They as a leaks in an oscillator to control Do know that we have published two are especially good grid Cut, drilled and engraved to order. Send rough sketch you and transmission. Data on actual tests made the Roberts Knockout Receivers? keying phone for estimate. Our New Catalog on Panels, Tubes and books on with 201-A and 202 tubes, and information concerning their Bakelite mailed on Rods all of genuine request, One is a treatise containing all the articles uses as grid leak resisters, are given. STARRETT MFG. CO. * and the other is just one article printed, MODULATION, 521 S. Green Street 111. on to build Ri48. MODULATION. Chicago, with complete blue prints how Methods. Radio. Jan. 1926, pp. 31-32. receiver. Price one dollar this wonderful "Speech Modulation Methods", Lieut. J. B. Dow. each. Write to Booklet Dept., Radio Three methods of speech modulation, the variable ab- RADIO FANS, a one-year' a subscription to Radio Broadcast will cost and the Garden N. Y. sorption method, grid voltage variation method, you four dollars, two years six dollars. Consider this expenditure Broadcast, City, are taken Several plate power variation method, up. circuits, a investment on for the future M being necessary your part develop- including the Meissner and a combination Heissing and ment of your own knowledge of Radio. Colpitts, are shown, and an account of their performances discussed in some detail. with the OMNIGRAPH LEARN THE CODE AT HOME ELECTRON TUBE RECEIVING SETS RECEIVERS, Transmitter will teach both the Wireless and Morse Codes right R.343- "lust Listen The Omni- THE OMNIGRAPH Automatic you Sbort-tt'ai-c. and Connected with Buzzer, Buzzer and Phone Radio. Jan. 1926, p. 33. '"> your own home quickly, easily inexpensively. 1 rrat>h mill do ike teathini" Short-Wave F. C. or to Sounder, it will send you unlimited messages, at any speed, from 5 to 50 words a minute. "A Good Receiver", Jones/ all over the world THE OMNIGRAPH is not an experiment. For more than 15 years, it has been sold For use on the very high frequency stations, a receiver used several of the U. S. Govt. in fact with a money hack guarantee. The OMNIGHAPH is by Depts. must be capable of sharp yet not too sensitive tuning. Herein the of Commerce uses the OMNIGRAPH to test all applicants applying for a Radio license. The Dept. is described a two-tube receiver operating on the capacity OMNIGRAPH has been successfully adopted by the leading Universities, Colleges and Radio Schools. feedback principle, the tube capacity being large enough for Send for FREE Catalogue describing three models. DO IT TO-DAY. this purpose, Oscillations are controlled by means of a tuned- are THE OMNIGRAPH MFG. CO.. 1 3K Hudson St., New York City plate circuit. Constructions! data and circuit diagram // you own a Radio Phone set and don't know the code you are missing most of the fun given.

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R343- ELECTRON TUBE RECEIVING SETS. RECEIVERS, Radio, Jan. 1926, 2gff. Reflex. " pp. '* Proper Reflex Circuit Assembly, L. W. Hatry. Some very good points on the construction of a three-tube reflex receiver are contained in this article. The use of con- densers and choke coils, and valuable suggestions pertaining to the circuit layout, accompany the article.

Rs53. METEOROLOGICAL SIGNALS. EARTHQUAKE Radio. Jan. 1926, pp. 35ff. RECORDING. " t Radio as an Aid in Recording Earthquakes," G. M. Best An account is given of a method of recording earthquake tremors automatically and accurately. Both the horizontal and vertical components of such tremors can be recorded, the exact time of such tremors being received from some naval time-signalling station and recorded on the same chart. A circuit diagram of the apparatus is shown.

R8oo (533). SOUND. PHONOGRAPH Popular Radio. Ian. 1926, pp 3-0. REPRODUCTION. "The New Wave-Transmission Phonograph," H. C. Harrison. Principles developed in the mechanical reproduction of sound by Bell Telephone engineers, have been applied to the phonograph, with the result that now five and one-half octaves are faithfully reproduced instead of three, as was the case in the old type of phonograph, according to the article. The construction of the new reproducer is described and shown in a diagram. Comparison is made between electrical and mechanical constants, the similarity being very evident.

R343. ELECTRON TUBE RECEIVING SETS RECEIVER, LC-26 Popular Radio. Jan. 1926, pp. 10-23. "How to Get the Most out of Your LC-26 Set," S. G. Taylor and L. M. Cockaday. Information is given concerning the theory and operation of the LC-26 receiver described in the December issue of Popular Radio. Details pertaining to antenna and ground con- nection, tubes and batteries to be used, installation, equipment, and operation of the receiver, are given. A shunt-plate feed unit, which the d. c. out of the loud speaker, is a feature (NSUL(NE keeps of this circuit. No matter what circuit you are building, the R8oo (530) PHYSICS. ATOM. final results will be better if you select Insuline Radio. Popular Jan. 1926, pp. 24-29 for the the material chosen Radio "The Atom," Sir William Bragg. panel by The place that the separate atoms take in forming crystals, Broadcast Engineers for the "Universal." is outlined. Most substances in very orderly and crystallize Laboratory tests prove Insuline to be high- regular fashion. X-Rays are used in analyzing transparent solids of crystaline structure to determine their arrangement. est in dielectric strength and other properties Examples and illustrations are given to show how atoms may conducive to clear reception. Also the most arrange themselves and how X-Rays detect this arrangement. easily worked panel material. Doesn't chip or INDUCTORS. INDUCTION R382. crack. Doesn't warp. Holds its lustre for all Radio, 1926, 30-39. COILS. "Popular Jan. pp. " Some New and Useful Facts about Coils, D. R. Demons. time. A discussion to distributed of induction pertaining capacity Insuline Panel for the "Universal," engraved coils, employing various types of windings and materials for mountings, is given. The distribution and strength by our exclusive Etch-O-Gravure Method, in of The fields of magnetic and electrostatic forces, depending and white or combination ; drilled ready to upon the kind of insulation used about the wire, is illustrated gold by means of graphs and diagrams, A lot of experimental set up: black or mahogany $3.50; "Frieze" data is given. finish, $4.00. R38i . CONDENSERS. CONDENSERS Insuline panels, drilled and decorated, are TUNING. ' Popular Radio. Jan. 1926, pp. 48-55. F9R "Sets that Jack and Dad Built "The Part That Your Condenser in furnished for all popular circuits. Also supplied Plays Tuning," a practical so-page book for build- H. Harries. J. in all standard size blanks. Insuline Sub-panels, ing the most popular circuits, with Condensers of the circular plate, the square-law plate, diagrams and instructions for the line are The drilled and mounted with metal sockets for and straight frequency plate, compared. hook-up, sent for 25 cents to cover effect each one of these condensers has on or broad- sharpness UV and UX tubes for all circuits. Bakelite cost of mailing and postage. ness of tuning covering the present broadcast band, is shown Brackets for etc. by curves, data, and discussion. A low minimum condenser Sub-panel mounting, etc., is really not what is desired in the opinion of the writer, but rather a condenser having a low resistance path at high frequencies. Ifyour dealer can' t supply you write us direct. for Free Booklet list. R38o. PARTS OF CIRCUITS; INSTRUMENTS. TONE METER. Send to-day and price QST. Jan. 1926, pp. 37-39- -The tone Meter," L. j. Wolf. A device indicating the condition of the plate supply current other of vacuum tube transmitters, is described. Any source ^g^^^t^ttfi* than a high voltage storage battery will give a more or less ^Branches in Trincipal Cities fluctuating power supply which necessitates filtering. An a.c. voltmeter is used in series with a condenser, the condenser preventing the d. c. from getting through the meter and acting also as a multiplier. The multiplying factor depends on the fre- quency, the capacity of the condenser, and the resistance of the voltmeter. Its value can be determined, as described. The (RADIO PANEL 6-PAR.TS CORP.) entire arrangement is called a Tone Meter. INSULINE BLDG., 59 WARREN STREET R375- DETECTORS AND RECTIFIERS. RECTIFIER, NEW YORK QST. Jan. 1926, pp. 4iff. Epom. "The Epom Rectifier and Filter," R. S. Kruse. The new Epom rectifier tube uses no filament but operates on the principle of ionization of a gas at low pressures within the tube. Argon gas is used for several reasons. The Why not subscribe to Radio Broadcast? By the year only $4.00; or two years $6.00, saving construction of the and the circuit are described . tube, diagram Send direct to & Garden New York. The tube may be used as a d. c. source of plate supply in $2.40. Doubleday, Page Company, City, transmitting tubes if properly loaded.

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Rii3. TRANSMISSION PHENOMENA. FADING AND ff. "B" Radio News. Jan. 1926, pp. 956 DISTORTION. FOR CLEAR, QUIET POWER "Unraveling a Broadcast Enigma"., A. Van A. Summers. Many data on fading and distortion of signals from broadcasting stations, which were accumulated by the Amer- ican T.& T Company are presented. Conclusions arrived at indicate that the ether is not a perfect carrier of electro- every magnetic waves, especially when these waves are near large masses of iron and steel. Refraction and absorption are probably the causes for most of the distortion observed. The author discusses at some length the conclusions arrived at reader through these experiments. Rii4. STRAYS. AURORA BOREALIS. Radio News. Jan. 1926, pp. 064 ff. of this "New Facts About the Aurora Borealis", C. L. Davis. RADIO magazine An experiment relating the effect of the Aurora Borealis on a telephone line, and the subsequent conclusions drawn from Storage "B" Battery this phenomenon, are described. A frequency of one cycle for fifteen minutes was noted on a voltmeter. iK Lasts Indefinitely-Pays for Itself Economy and performance unheard of before. Recharged at a nejrli- IB , pure and quiet. Kible cost.. Delivers unfailing power that clear, Rno. RADIO WAVES RADIO WAVES. Approvedved anan-t listed aa Standard by leading Radio Authorities, mclumclud- Pci. Inst. Standards, Radio Newa Radio News. Jan. 1026, pp. 066 ff. in* POD.OD. RaRadio Laboratories, Pop. Lab Lefax, In-., and other important Institutions. Equipped with .. Are Radioio Waves? I . needs V ", Riley. Solid Rubber Ca*e,nn Insurance afcnlnac acid ard leakage. Extra <-la ;a lieavy rugged plates. Order yours todayl An elementary explanation of the nature of radio waves, is heavy jara. "" Just fltate number of batteriea Stress and strain, of f A/fOXJTJV given. displacement elds, electrostatic MUJNtl wanted and we. _ wwill shin day order and electro-magnetic fields of force, questions on radiation, Isreceived. Extra offer: 4 batter-lea ineeries (96 volts). *!i>.r>u. P/ exp csiman after examining batteries. 6 percent discount ror cash current and voltage relations in antennae, are some of the with order. Mail your order now! : subject? d scussed. WORLD BATTERY COMPANY c. 1219 So. Wabash Ave., Dept. 78 Chicago* Hit R 1 34.45. SUPER REGENERATIVE ACTION. Maker* of tke Famous World Radio'*A" Storage Battery SUPER-REGENERATIVE Prices: 6-voU,logAmp.glX.S5; lsoAmp.tl3^5;240Amp.ftM

RjSz. INDUCTORS. INDUCTION Radio News. Jan. 1926, pp. 086 ff. COILS "Which Type of Coil is Best?", An exhaustive study of various types of coils, dealing with their overall efficiency, is presented. Circuits used in the A convenient station log and wavelength scale Very measurement of resistance at high frequencies, graphs showing simple to attach and is a permanent log. the efficiency and distributed capacity of coils and the result SOLD BY MAIL ONLY obtained through experimental hookups, are discussed. The PRICES 1 for 15c, 2 for 25c or 3 for 35c. best all around coil, according to the writer, consists of bell wire wound on a bakelite tube in eliminates normal ordinary the regular MUELLER RADIO COMPANY Practically fashion. static reduces excessive static 533 Bush St. Toledo, Ohio to a minimum. Eliminates R2OI.7 USE OF HIGH-FREQUENCY OSCILLOGRAPH. TUBES, necessity of outside aerial with OSCILLOGRAPH set- makes re- any a squealing Radio News. Jan. 1926, o88ff. W.E. AT WHOLE ceiver non-reradiat- pp. absolutely "The Cathode Ray Oscillograph In Radio Work", PARTS SALE PRICES ing increases selectivity im- Dr. C. B. Bazzom. S-C tone proves quality. The author reviews the elementary principles concerning electric waves and their to Elevates an inexpensive receiv- forms, referring pitch and quality of sound as an To these wave the ing set to the dignity and analogy. study forms, cathode is of quality of a high-priced re- ray tube, illustrated, great importance in high circuits. The tube used ceiver. frequency here was developed bv the Western Electric Company. Electric and magnetic Enables a set to in deflections of the electron stream and coils good bring through plates SHU RE RADIO 19 S. Wells, Chicago far-distant stations -with a full, near these electrons, picture the resulting wave forms for 0., clear, smooth tone not before closer analysis. Lissajou figures produced, enable the dreamed possible. experimenter to synchronize circuits or adjust them to manv different ratios of oscillations. Ask your dealer or send pur- chase direct and price you 'will R343 ELECTRON TUBE RECEIVING SETS, RECEIVERS, ,/Gets Everything but Noise! be supplied. Radio Progress. Dec. 15, 1925.00. !3ff. Deresnadyne. \< a Popular Radio", H. Marx. to eliminate all Price, $28.50. "Revamping J. Amazing new Aerial guaranteed poi motor nui. . An analysis of the five-tube Deresnadyne receiver is given, noises surh as leak} transformers, gen<-raiors. Delcr> Plants, etc. Cuts static, regeneration howls and squeals the and ', showing wiring diagram method of operation. This 1-2. Dr. Gehriff, Oakland, Gal., says improves reception 60%. Mr. Boeck receiver is equipped with a B-eliminator, and trickle charger for ilundrt-iis other testimonials. Wonderful results. , Grand Haven, Mich., heard 3 foreign stations during tests with the A the is built in the thus GENERAL INSTRUMENT battery; speaker cover, making Kane Antennae. Easy to install. - this set complete. Oscillations are prevented in the tuned 5ft 1OO Brings BLUE PRI NT- Working Drawings *** * Complete Instructions for Erecting. ' radio frequency stages by controlling the plate voltage iBt send blfl (or check), f i-nit- o-ianti'v. Send TODAY. CORPORATION dollar ' W. Monroe. Chicago on the tubes through a series resistance. The coil angle may M4 423 Broome St., New York City also be varied, depending upon the type and characteristic of the tubes used. Other details of operation are mentioned. This is a good time to subscribe for R342.7. AUDIO-FREQUENCY AMPLIFIERS. AMPLIFICATION. RADIO BROADCAST. RADIO BROADCAST Order your copy of Radio Broadcast from your Jan. 1926, pp. 308-312. Audio Fre- news dealer or radio store. Make sure that he quency. Through your dealer or direct, by the year only $4.00 "The Requirements for Better Audio Amplification," reserves a copy for you each month. If your DOUBLEDAY, PAGE & CO, GARDEN CITY, NEW YORK favorite radio store does not stock the magazine K. Clongh. An of the various instruments used in sound write us giving name of radio dealer and address. analysis pro- duction show that a good amplifying device should respond equally well to frequencies from 32 to 8192 cycles or more. A full logarithmic scale is considered best in plotting charac- teristics of amplifying units. Of considerable importance are the characteristics of the tubes used in audio amplifiers, and good results are obtained only when the entire amplify- ing unit is tested as one device. It is stated that in the present type of resistance-coupled units, the lower notes are Of "Your somewhat Transformers a cruciform Town suppressed. having core construction seem to give best results. Reference is Parts Kits made to Mr. Crom's article on audio amplification in the Be popular. In demand everywhere. Have fun Sets | RADIO BROADCAST. Earn your welcome. Charm your friends with your Radio's Newest Oct., 1925, F. i You need this big FREE book. I R342.6. RADIO-FREQUENCY AMPLIFIERS. R. AMPLIFIERS, A practical guide to success in I RADIO BROADCAST. Oscillations in. get building. Gives advanced I Jan. 1926. pp. 3wff. Shows all newoit I " hook-ups. Methods for Controlling Oscillation in R. F. Circuits." and kits, built seta I parts up Bernard. SAXOPHONE J. ready for use, battery eliniina-l 3 free lessons tors, radio's newest creations. I Many methods are used in r. f. amplifiers to prevent tubes Teach yourself, give you quick Writ* for Copy free, also send I from oscillating or to control oscillations. Some of these easy start. Try any instrument in your own name of radio fan. Send to-day 6 free. See what can do. .J are discussed briefly by the author. A somewhat novel home days you Easy method is employed in the "Counterphase" circuit, diagram- terms if you decide to buy. Send now for li5 . BARAWIKCO. med and described here. This scheme makes use of a com- beautiful free literature. A postal brings details. bined resistance and and is considered OtalogN capacity control, very Buescher Band Instrument Co. (4> 1 102-109 S. Canal St., Chicago effective over the entire range of frequencies to which the re- 1221 Bue*cher Elkhart, Indiana ceiver is tuned. Block

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LOW LOSS Tuners and Coils for all circuits 3 Circuit Amateur and Broadcast tuners $7.00 Tuned K. F. Transformers (each) $2.00 NEW COILS .X. Diamond of the Air Browning Drake Colls $7.00 - CORNHILL BOSTON, MASS. Superdyne Coils 7.00 Roberts Coite 7.00 This is a time to subscribe Superheterodyne Oscillator and Antenna Coupler .... 6.00 good for Basket Weave coils to order. Write for literature. RADIO BROADCAST Divenport Radio Laboratories 1717 W Locust Street. Davenport. Iowa Through your dealer or direct, by the year only $4.00 Doubleday, Page & Company Garden City, New Yorf

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Modernize Your Radio Set/

The International Tests

AS MIGHT be expected, we were ** simply inundated with letters from all quarters of the country and abroad, after the recently concluded International Tests. Space limitations permit the publi- cation of only three or four here, but these convey the sentiment expressed in the letters of many other correspondents.

Editor, RADIO BROADCAST, Doubleday, Page & Company, Garden City, New York.

SIR:

I hear over KCO'S news items that California IHORDARSON was silent during the test period. I wish to refute this statement for I distinctly heard KNX, Hollywood, on two different occasions while trying for British stations. ... I think Trade-Mark Registered KNJ was on the air too, for 1 heard a station at a All Frequency Amplifier setting on my dials where this station usually comes in, but I could not be positive about this. There is nothing too small for California to do. Write for free Very truly yours, circular Price descriptive 0.00 F. W. DALLEY. Lyons, Colorado. Are you still using primitive methods of amplification? Why not make your receiver an up-to-date model by installing Autoformer Editor, RADIO BROADCAST, amplification the ultimate in reproductive equipment? Doubleday, Page & Company, Garden City, New York. The Autoformer, a step up impedance amplifier, reproduces with full SIR: volume those bass notes lost in ordinary transformer amplifiers. Just a line in appreciation of last week's silence those of and The Autoformer provides the unrestrained flow of distortionless tests, especially Friday Saturday evenings. Is it possible to have an music. It records everything from the slightest shading to the arrangement for regular zonal silence periods, greatest extreme of volume, intensity, and timbre. thus allowing uninterrupted sectional exchanges of programs? Here is one unsolicited vote in Better volume control favor of such a scheme. Very truly yours, More volume on distant stations R. M. BOULDEN, Los California. bass note amplification Angeles, *FullGreater clarity on all signals Editor, RADIO BROADCAST, OTHER THORDARSON TRANSFORMERS Doubleday, Page & Company, Garden City, New York. R-200 Amplifying Transformer B-Eliminator Transformer Standard Amplifying Transformer B-Eliminator Chokes SIR: Power Amplifying Transformer Battery Charging Transformers Organize an anti-bloop club with a big turn- Power Transmission Equipment Interstage Transformer out at first meeting. What are the other cities doing along this line? CO. Very truly yours, E. M. RAY, WORLDS OLDEST AND LARGEST EXCLUSrVTE^TRA NSPOHMER MAKERS Rochester, Minnesota. Chicago. U.S.A.

Editor, RADIO BROADCAST, Doubleday, Page & Company, Now is the time to subscribe for RADIO BROADCAST Garden City, New York. Through your dealer or dirzct, by the year only $4.00 GARDEN SIR: DOUBLEDAY, PAGE & CO. CITY, NEW YORK I am a regular reader of your excellent maga- zine, and am also a confirmed radio fan, being interested in the reception of both broadcast ediate Stock matter and code. I was greatly interested in the Jnun Shipment from International Tests, although they were a failure as far as I am concerned. In 1924, I received HAVE MERCHANDISE British stations with a modified three-tube Reinartz set. This year, nothing but interfer- IT ence, static, bloopers, and almost everything yOU JVEED radio One WHEN to injurious satisfactory reception. is to dealers thing that has come to my attention is that dur- Catalog 466^B free ing the period from half-moon until the moon to radio is not what it WHOLESALE EXCLUSIVELY begins wane, reception should be it is noisy. At other periods, when there is no moon, reception is much better, I have found. During Test Week, the moon was

well full. I have been this ' "^ pretty watching I wonder if 929 PENN AVENUE phenomenon since last July. any fHt one else has noticed it. Wishing you continued

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Tested and approved by RADIO BROADCAST 718 RADIO BROADCAST ADVERTISER

success, and next year or whenever you decide to have another week of international tests let's hope that there will not be so many bloopers If they all make sets described in RADIO BROAD- CAST, there certainly will not be. Very truly yours, G. JOHNSON. Bloomington, Illinois.

A Setback to the Florida Boom

MANY districts code interference has IN 12-Cell-24-Volt been materially reduced through a gen- eral cooperative campaign of the news- Storage'B'Battery and magazines which circulate Positively given free with each papers purchase of a WORLD "A" in those areas, in which was Storage Battery. You must pressure send this ad with your order. to bear on the offenders. There WORLD Batteries are famous brought for their guaranteed quality are still too districts, however, where and service. Backed by years many of successful manufacture and tuned transmitters are a source of Convert thousands of satisfied users. broadly your present Equipped with Solid Rukbtr Case. an insurance afraingt acid end leak- constant annoyance to listeners of both age. YoupaveoOpercentaodBeta radio receiver into a 2-Year Guarantee local and distant broadcasting stations. Bond in Writing ' Approved The Florida peninsula, it would appear, socket set with a "tell their friends." That 'a our bent Proof and Listed light of performance, bend your order in today. from this letter suffers badly from coast to Solid Rubber Case Radio Batteries as Standard 6-Volt. 100-Amperea 511.25 by Leading shore interference. Balkite Trickle 6-Volt. 120-Amperes...... 13.25 6-Volt. MO-Amperea 14.0O Authorties Charger Solid Rubber Case Auto Batteries 6-Volt, ll-Plate $11.25 and Balkite "B" 6-Volt. 13-' late . torlea, Popular RADIO Science Insti- Editor, BROADCAST, 12-Volt, 7-.'Iate . 16.OO tute of Stand- & Send No fc' ards. Popular Doubleday, Page Company, FANSTEEL PRODUCTS CO., Inc. Money Radio Labora- ill ehiDday17 order lais recI Garden New York. North Illinois press C. O D., subject to yourS examination City, Chicago, on arrival. FREE "B" Battery included. Extra Offer: 5 per cent discount for caab . . in full with order. Buy now and tret a 1 suar- Y aod Le1 "t. nil teed batter _ at 50 per cent savins' to you. Sir: WORLD BATTERY COMPANY to shore transmission is 1219SO. WabasliAve., Dept. 2 4 CHICAGO, ILL. Ship responsible in this locality for the worst form of interference S. t your Radio Dials mt 210 metera tor the new 1000 encountered. will sit on the World Storage Hattery "Sparks" key Thorola Receivers Salttation. World WSBC. Chicago. at about the time the broadcast is STORAGE BATTERIES just program at its and often it seems as if he had held * KFAF* best, and Speakers up his work to fill the air between then and twelve o'clock. The wonderful New Year's Must treat from wjz was perfect as regards volume Outperform and modulation, but all through the stellar offer- Reichmann Company, 1725-39 W. 74th St., Chicago ing of McCormack and Bori there was only one Catalog & Guide brief song not ruined by code. TARTS; Very truly yours, Send now for this valuab f FREDERIC B. HYDE, BOOR-VPS: I FREE book . Fullofadv hook-ups, parts and kits. I Miami, Florida. SET A real guide. Shows fac* I fbe tory built sets and the new I Distortionless Jfmp/ifi JBltf ideas in radio. Send at I Insure distortionless amplifications and a clarity once. No No I charge. A Letter from the Philippines of tone not obtained through any other resistance. obligation. Please in- I All capacities 12,000 ohms and up. List price $1.50. dude name of radio fan. I Special sizes to order. Write for full information. ^TAKING Horace Greeley's "Go West" Crescent Radio Supply Co. 1-3 Liberty St., Jamaica. N. Y. BARAWIKCO. 1 thoroughly to heart, apparently irre- of human element, one 102-109 S. Canal St. Chicago spective any copy of RADIO BROADCAST has monthly wended its weary way right out to the Philippines, $6.50 we from that so enthusi- " there, presume Itgets astic letter following, to be eagerly read by least "satisfied customer." APOLLO that at one The letter: last Parlor Model mile" Editor, RADIO BROADCAST, & Stands 22 inches high, Doubleday, Page Company, has a ten inch bell, gives Garden City, New York. faithful reproduction and may be varied from a to a torrent SIR: whisper IRGAP of sound by the adjust- I have already received the new size November able unit control with- SOCKET and December numbers of the RADIO BROAD- out the least loss of the sweet mellow. clear tones CAST. I want to on the Will rid your set of those squawks, congratulate you that are found in the howls and frying noises. They pre- progress and success your magazine is making. Apollo Speakers. Mail orders filled. vent closed circuit absorption of cur- It is the best magazine of its kind that I have promptly of Send no rent, inter-coupling circuits, ever seen and so cheap that can money, just feedback and undesirable capacity. yet anybody pay the poitman. THEY MAKE ANY CIRCUIT more afford to subscribe. Its articles are very inter- stable and sharpen tuning, resulting esting and highly instructive. Its hook-ups are in and clearer tones with more purer all "knockouts." HARD RUBBER PANELS volume particularly on distant Size Black stations. Before I subscribed to this magazine ! hadn't 10.. .32 an of radio; now I am to that At all dealers 75c each inkling proud say 12.. .39 I am the first home-constructor in this province. U.. .42 Sent direct if dealer cannot your 18. .56 supply you. The department "For the Radio Beginner" 21. . .64 should be continued as it is always very instruc- 24. . .75

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