Radio Digest (Apr 1925-Jan 1926)

RADIO DIGES T— Illustrated mber 12, 1925 KDKA LEADS WAY TO LESS INTERFERENCE (Continued from page 1) set. a type of transmitter on which constant frequ difficult to maintain. After tests demonstrated that the crystal would control the wave length, and that normal power could he used with it. H. P. Davis, vice ■"' the Westinghouse Electric and Manufacturing company, announced that the regular KDKA "09-m r Wi -Jtinghouse stations. WBZ, KTW, Chicago, and .X Hastings. Xebr.. would he rice. Tests of the run by WB3 -meter transmitti s an be ground for length no matter how low or ' Slipping Waves Greatest Trouble Although with the simple, I roadly tuned receiving sets a shift in the wave length is scarcely noticeable, with the sharply tuned receivers ing sold the great est source of interference is the station that slips off its assigned frequency. Since the station wave lengths each are separated only by ten kilocycles, it is a serious matter when a transmitter changes its wave lengths even as little as two kilocycles, which in the case of a station operating on 309 meters, would be but 0.2 of one per cent. If a shift greater than two kilocycles occurs, there is a whistling sound beat note, or other distortion heard in the receiving set. and the signals from two stations are jumbled together so that neither can be heard clearly. Hard to End Variation This shifting of wave length has been difficult to prevent, as it may be caused by such seemingly trivial things as a sagging of the antenna or a variation of the current used in the transmitter. It has been known to scientists that certain crystals have the power of vibrating at frequencies in the Radio range. These are called piezo crystals. It was learned that the frequency at which the crystal vibrated was governed by its size and shape. It was also learned that by using the crystal in a specially constructed circuit, and building the crystal's oscillation on up through the high power transmitting set, the wave length emitted is exactly the same as that of the crystal. Xo ordinary change in the adjustment of the transmitting set can cause any appreciable change in the wave length. The use of the crystal also improves the quality of the transmission by reducing the amount of distortion. The crystal used by KDKA is about the size of a half dollar. WEE CRYSTAL BOSS OF GIGANTIC TUBES HOOVER HINTS AT NEW RADIO LAWS MEASURES SKY ROOF (Continued from page 1) th' skip distance" which was checked by a simple me< hanical device by means of which the effective distance of the deflecting layer may be actually measured. In the pioneer work of short-wave transmission, it was the experience that signals could be picked up at distances 40 or Th< ii they disappeared. Th' • -:.in picked up at points . of miles distant. The Intervening dead space of non-reception became known as the "skip distat In seeking to account for this a theory was developer] at the research laboratory that there was a relation between the earth's mag Id, the frequency of the waves used, skip distances observed and the height of the Heaviside layer. This relation could be. and was. worked out mathematically using data contributed by the member American Radio : • ura 1 nd their coworkers in foreign countries. Will Bring Cheaper Communication The joint experiments with th< Carnegii institution approached th< solution of the problem from a different, angle, demonstrating definitely the existence of two ■hem arriving by way of the other by way of the layer. From these experiments estimates of eff. ht of the layer were made-, and > entially in agreement with the estimates derived from ' is on the skip distance. The knowledgi lied will play an important part in further advancing the Radio art. The naval research laboratory is now in communication with practically try In the world using short Urid g of the principles liv ed to the point where bi definitely tated that a high frelon can be built that will give i" tter d longer range than the pi high-i i 000,000 ■ ..ration will be KFNF Radio Operator Weds SHI aln In • aded the ra r ■'■< Hem y Fit '■ i .1 In d^rt of KF.NI >r Bu man I rtright, of Neon, Iowa. Ten-kilowatt transmitting tubes, one of which is shown above, now look askance upon small piezo crystals such, as those pictured at the right of the tube, since KDKA has found the wee crystals capable of holding transmitters on their exact assigned wave lengths. The two top crystals have Been ground for usa, while the one at the bottom is the rough product. The size and shape of a piezo crystal governs the wave length or frequency at which it will oscillate. Best Invention to Get Medal LONDON. — Sir Arthur Stanley, president of the newly-formed Radio league, which is already said to have the largest membership of any Radio club in the world, has offered a gold medal for the best Radio invention produced during the next six months. This award, which will be known as the Stanley medal, will only be open to members of the league. Believes Fourth Conference Will Settle Much — Judge Davis Is Busy on Legislation , WASHINGTON, D. C. — Judge Davis, solicitor of the department of commerce. has given must thought to the question of new Radio legislation. Secretary of Commerce Hoover recently stated, but the secretary himself has not yet taken the matter up. He is of the opinion that considerable will be brought out along these lines at the forthcoming Radio conference. Questioned the other day on the subject. Jlr. Hoover stated that he has not yet decided on. the date for the Radio conference but he said that he would make announcement of the date at least thirty days before the conference is to convene. Five Continental Stations Change Wave Lengths PARIS. — Among changes in wave lengths intimated by prominent foreign stations within the last week or two are the following: Koenigswusterhausen, Germany: Xew uniform length, 1.300 meters. Radio-Catalana. Barcelona, Spain: New length, 46 0 meters. Dortmund, Germany: New length, 265 meters. Cointrin, Geneva: Experimental length, 1.100 meters. Nottingham, England: Xew length, 325 meters. Russian Workers Become Fans MOSCOW. — The amazing progress of Radio in Russia within the past few months is strikingly shown in the official figures just published that over 6,000 workers' clubs and nearly 12,000 public reading rooms in Russia have been fitted with receiving sets. Madrid Broadcasts Till 1 A. M. MADRID. — The recently opened Madrid station is trying an experiment in late broadcasting of concert programs. These start daily at 11 p. m. Madrid time and go on. till 1 a. m. CONTENTS Radio Digest, Illustrated, Volume XTV. Number 10, published Chicago, Illinois, September 12. 1925. Published weekly by Radio Digest Publishing Company, 510 N. Dearborn Street, Chicago, Illinois. Subscription rates, yearly. Five Dollars; Foreign Postage One D"llar additional; single conies Ten Cents. Entered as second class matter at the post otTiee at Chicago, Illinois, under the Act of March 3, 1879. All the live News of Radio 1 to 7 WTIC, in Hartford "The Insurance City" 5 Advance Programs for the Week 8 to 14 An Evening at Home with the Listener In, a chart in Eastern and Central time, showing when to listen in for your favorite stations 15 Editorials, Indi-Gest and Condensed by Dielectric 16 Easy Methods of Making Receivers Selective, Part II — Tuned Jt.T. NeutraUzed and Otherwise, by John Q. Ryan 17 Construction of an Edison Storage B Battery, Part I — Rack, Panel and Elements, by John DeQuedviUe Briggs 19 A. B. C. Course in Radio Fundamentals, Chapter KXV — Amplification Circuits Used in Radio (Continued), by David Penn Moreton 20 Variable Coupling on Tuned R.F.; Other Kinks 21 Questions and Answers 22 Directory of Radiophone Broadcasting Stations, Part III 23 Looking Ahead There Were Many Other Announcers ill the race besides the winner, so next week's issue will contain the final standing of every man entered in the 1925 Gold Cup Best Announcer Contest. Radio Fans Have Scrap Books wherein they paste photos of their favorites just as do the movie fans, so next week we will publish pictures of the winner and the fifteen who finished right below him that will be worthy of places of honor in your own Radio Who's Who. Belgium and Its Radio-Belgique will be the next topic of Fred Smith, America's first Radio Ambassador. Air. Smith has forwarded some pictures of the artisis of that station and also gives a few sidelights on beggars and rough railroad trips. Part Two of the Storage B Battery series will complete the instructions for you to follow in cutting down the high cost of high voltage. Professor Moreton Next Discusses the use of a tube as a regenerative detector and as an oscillator in his A. B. C. Radio Fundamentals series. Newsstands Don't Always Have One Left WHEN YOU WANT Radio Digest YOU WANT IT! BE SURE OF YOUR WEEKLY COPY BY SUBSCRIBING NOW SEND IN THE BLANK TODAY Publisher Radio Digest, 310 N. Dearborn St., Chicago, Illinois. Please find enclosed check M. 0. for Five Dollars (Six, Foreign) for One Year's Subscription to Radio Digest, Illustrated. Nam» ......... Addreii City KILOCYCLESREPLACE WAVE LENGTH DIALS BUREAU OF STANDARDS TO TELL HOW TO CHANGE Rapidity of Waves Rather Than Length Designation Will Aid in Logging Stations By Ii. M. Lamm WASHINGTON. D. C. — In Radio, the term "kilocycle" is gradually taking the place of "wave length" says the bureau of standards. All listeners and users of sets will want to know and understand the new rating which increasingly governs their tuning in. The making or logging of dials is found to have certain advantages when in the newer terms. Already one of the oldest stations is announcing its broadcasts on the "kilocycle" or frequency rating. It is really quite simple, for frequency (waves per second) replaces wave length (in meters). Just as a musician can vary the number of "oscillations" or vibrations of his vocal cords but cannot control the length of the sound waves, which vary with the medium, so a Radio station can vary the number of oscillations per second, and let the wave lengths be what they will. A high tenor "C" gives sound waves two feet in length, but the standard rating is frequency, or pitch, which is in this case 512 vibrations per second. What Frequency Is Frequency is the number, of waves produced per second, or the number on the air after one second of transmission. "Kilocycle" means a thousand cycles. Hence a broadcast on a 500-kilocycle frequency gives out 500,000 Radio waves per seconds To aid Radio amateurs and experts, the bureau of standards is about to issue a table so that all, at a glance, can translate from the old rating by "wave lengths" (in meters) to the new rating by frequency (in kilocylces). and vice versa. Radio waves travel with the speed of light, about 300.000 kilometers per second. (A kilometer is 1,000 meters or 0.62137 mile.) This is the sum of all the waves emitted in one second. Dividing this by the wave length in meters gives the frequency in kilocycles; dividing by the frequency in kilocycles gives the wave length. Bureau Gives Example The bureau gives this simple rule to obtain the frequency when the wave length (in meters) is known: Divide 300.000 by the wave length in meters. The answer is in kilocycles. Likewise the other way around: divide 300,000 by the number of kilocycles to get meters. As the new system proposed by the international and national Radio conference is taken up by the broadcasting stations and placed into effect by the government in assigning station frequencies, it will become increasingly important to translate from wave length to frequency in order to tune in at all. World's Series Games Over KTHS Is Plan "Wonder State" Fans Will Hear Dixie Series Also HOT SPRINGS NATIONAL PARK, Ark. — Residents of the "Wonder State" will be able to follow the progress of the World's Series and the Dixie Series battles this year for the first time play-byplay by Radio from their own home state broadcasting station through KTHS the 750-watt transmitter of the New Arlington hotel here, it has been announced by Director G. C. Arnoux. A play-by-play account will be received by KTHS by direct wires to the ball grounds where the two series are played and each day. including balls and strikes, will be given out. Light Opera Company Is Popular with Radio Fans CHICAGO. — Opera of that variety known as "light" is fast becoming one of the most popular broadcast features on the station calendar of WEBH located here at the Edgewater Beach hotel. Already six of these selections of music of the popular, but good variety, have been received with much pleasure by the station's audience. Howard Neumiller, musical director of WEBH, is in charge of the presentations which are given by a company made up of several of the best known and qualified artists of the Chicago territory. The light opera programs will continue to be Radioed on every Friday night from 9:30 until 10:30. central daylight saving time. The microphone used for broadcasting the chimes of Big Ben is wrapped round with cotton batting and enclosed in a football bladder against tin weather.