Radio Broadcast (Nov. 1925-Apr 1926)

714 RADIO BROADCAST ADVERTISER every reader of this magazine needs G.I. Static Reductor TRADE MARK Practically eliminates normal static — reduces excessive static to a minimum. Eliminates necessity of outside aerial with any set — makes a squealing receiver absolutely non-reradiating — increases selectivity — improves tone quality. Elevates an inexpensive receiving set to the dignity and quality of a high-priced receiver. Enables a good set to bring in far-distant stations with a full, clear, smooth tone not before dreamed possible. Ask your dealer— or send purchase price direct and you will be supplied. Price, $28.50. GENERAL INSTRUMENT CORPORATION 423 Broome St., New York City Order your copy of Radio Broadcast from your news dealer or radio store. Make sure that he reserves a copy for you each month. If your favorite radio store does not stock the magazine write us giving name of radio dealer and address. RADIO $SffiBR Sets — Parts — Kits I Radio's Newest R 1 1 3. Transmission Phenomena. Fading and Radio News. Jan. 1926, pp. 956 ft". Distortion. "Unraveling a Broadcast Enigma"., A. Van A. Summers. Many data on fading and distortion of signals from broadcasting stations, which were accumulated by the American T.& T. Company are presented. Conclusions arrived at indicate that the ether is not a perfect carrier of electromagnetic 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 through these experiments. R114. Strays. Aurora Borealis. Radio News. Jan. 1926, pp. 964 ff. "New Facts About the Aurora Borealis", C. L. Davis. An experiment relating the effect of the Aurora Borealis on a telephone line, and the subsequent conclusions drawn frem this phenomenon, are described. A frequency of one cycle for fifteen minutes was noted on a voltmeter. R 1 10. Radio Waves Radio Waves. Radio News. Jan. 1926, pp. 966 ff. "What Are Radio Waves?", J. Riley. An elementary explanation of the nature of radio waves, is given. Stress and strain, displacement of f elds, electrostatic and electro-magnetic fields of force, questions on radiation, current and voltage relations in antennae, are some of the subject' d'scussed. R134.45. Super Regenerative Action. Super-Regenerative Radio News. Jan. 1926, pp. 976 ff. Action "Super Regeneration and the Future", A. K. Laing. The original Armstrong super regenerative circuit, modified somewhat, is presented, with points on construction and operation given. These, it is claimed, will make this type of amplification as popular as the super-heterodyne. The drawbacks of the circuit are enumerated and taken up in detail. The circuit is said to give much more amplification on the higher frequencies than on the low ones. R134.7;. Super-heterodyne. Super-heterodyne. Radio News. Jan. 1926, pp. 982 ff. "An Improved Laboratory Super-Heterodyne" F. R. Pfaff. A seven-tube super-heterodyne covering the frequencies from isokc. to 500okc. (550 to 50 meters) using plug-in coils, is described. The oscillator is connected ahead of the first detector in this circuit. Complete constructional data are given. R382. Inductors. Induction Radio News. Jan. 1926, pp. 986 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 measurement of resistance at high frequencies, graphs showing the efficiency and distributed capacity of coils and the result obtained through experimental hookups, are discussed. The best all around coil, according to the writer, consists of ordinary bell wire wound on a bakelite tube in the regular fashion. R201.7 Use of High-Frequency Oscillograph. Tubes, Oscillograph Radio News. Jan. 1926, pp. g88ff. W. E. "The Cathode Ray Oscillograph In Radio Work", Dr. C. B. Bazzoni. The author reviews the elementary principles concerning electric waves and their forms, referring to pitch and qualitv of sound as an analogy. To study these wave forms, the cathode ray tube, illustrated, is of great importance in high frequency circuits. The tube used here was developed by the Western Electric Company. Electric and magnetic deflections of the electron stream through plates and coils near these electrons, picture the resulting wave forms for closer analysis. Lissajou figures produced, enable the experimenter to synchronize circuits or adjust them to many different ratios of oscillations. R343 Electron Tube Receiving Sets, Receivers. Radio Progress. Dec. 1 5, 1925. pp. 13ft. Deresnadyne. "Revamping a Popular Radio", H. J. Marx. An analysis of the five-tube Deresnadyne receiver is given, showing the wiring diagram and method of operation. This receiver is equipped with a B-eliminator, and trickle charger for the A battery; the speaker is built in the cover, thus making this set complete. Oscillations are prevented in the tuned radio frequency stages by controlling the plate voltage on the tubes through a series resistance. The coil angle mav also be varied, depending upon the type and characteristic of the tubes used. Other details of operation are mentioned. R342.7. Audio-Frequency Amplifiers. Amplification, Radio Broadcast. Jan. 1926, pp. 308-312. Audio frequency. "The Requirements for Better Audio Amplification," K. Clough. An analysis of the various instruments used in sound production 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 characteristics 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 amplifying unit is tested as one device. It is stated that in UKpresent type of resistance-coupled units, the lower notes are somewhat suppressed. Transformers having a cruciform core construction seem to give best results. Reference is made to Mr. Crom's article on audio amplification in the Oct., 1925, Radio Broadcast. R342.6. Radio-Frequency Amplifiers. R. F. Amplifiers, Radio Broadcast. Oscillations in. Jan. 1926, pp. 3soff. "Methods for Controlling Oscillation in R. F. Circuits," J. Bernard. Many methods are used in r. f. amplifiers to prevent tubes from oscillating or to control oscillations. Some of these are discussed briefly by the author. A somewhat novel method is employed in the "Counterphase" circuit, diagrammed and described here. This scheme makes use of a combined resistance and capacity control, and is considered ver\ effective over the entire range of frequencies to which the receiver is tuned. FOR CLEAR, QUIET "B" POWER RADIO Storage "B" Battery II voi"! Lasts Indefinitely— Pays for Itself Economy and performance unheard of before. Recharged at a negligible cost. Delivers unfailing power that Ib clear, pure and quiet. Approved and listed as Standard by leading Radio Authorities, including Pop. Radio Laboratories. Pop. Sci. Inst. Standards, Radio News Lab.. Lefax, Inc.. and other Important Institutions. Equipped with Solid Rubber Case, an Insurance against acid and leakage. Extra heavy glass jars. Heavy rugged plates. Order yours todayl SEND NO MONEY *2St$SSlZS%tfdLSg%S isreceived. Extra Offer: 4 batteries in series (96 volts), $ in. fill. Pay exp-easman after examining batteries. & percent discount ror cash with order. Mail your order flow! WORLD BATTERY COMPANY 1219 So. 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