Radio Broadcast (Nov. 1925-Apr 1926)

RADIO BROADCAST ADVERTISER 713 R343. Electron Tube Receiving Sets. Receivers, Radio. Jan. 1926, pp. 29ff. Reflex. " 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 condensers and choke coils, and valuable suggestions pertaining to the circuit layout, accompany the article. Rs53. Meteorological Signals. Earthquake Radio. Jan. 1926, pp. 35ff. Recording" 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. R800 (533). Sound. Phonograph Popular Radio. Jan. 1926, pp 3-9. 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, Popular Radio. Jan. 1926, pp. 10-23. LC-26 "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 connection, tubes and batteries to be used, installation, equipment, and operation of the receiver, are given. A shunt-plate feed unit, which keeps the d. c. out of the loud speaker, is a feature of this circuit. R800 (530) Physics. Atom. Popular Radio. Jan. 1926, pp. 24-29 "The Atom," Sir William Bragg. The place that the separate atoms take in forming crystals, is outlined. Most substances crystallize in very orderly and regular fashion. X-Rays are used in analyzing transparent solids of crystaline structure to determine their arrangement. Examples and illustrations are given to show how atoms may arrange themselves and how X-Rays detect this arrangement. R382. Inductors. Induction Popular Radio, Jan. 1926, pp. 30-39. Coils. "Some New and Useful Facts about Coils," D. R. Clemons. A discussion pertaining to distributed capacity of induction coils, employing various types of windings and materials for mountings, is given. The distribution and strength of the fields of magnetic and electrostatic forces, depending upon the kind of insulation used about the wire, is illustrated by means of graphs and diagrams. A lot of experimental data is given. R381. Condensers. Condensers Popular Radio. Jan. 1926, pp. 48-55. for Tuning. "The Part That Your Condenser Plays in Tuning," H. J. Harries. Condensers of the circular plate, the square-law plate, and the straight line frequency plate, are compared. The effect each one of these condensers has on sharpness or broadness of tuning covering the present broadcast band, is shown by curves, data, and discussion. A low minimum condenser is really not what is desired in the opinion of the writer, but rather a condenser having a low resistance path at high frequencies. R380. Parts of Circuits; Instruments. Tone Meter. QST. Jan. 1926, pp. 37-39. "The Tone Meter," L. J. Wolf. A device indicating the condition of the plate supply current of vacuum tube transmitters, is described. Any source other than a high voltage storage battery will give a more or less 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 frequency, the capacity of the condenser, and the resistance of the voltmeter. Its value can be determined, as described. The entire arrangement is called a Tone Meter. R375. Detectors and Rectifiers. Rectifier, 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 construction of the tube, and the circuit diagram are described. The tube may be used as a d. c. source of plate supply in transmitting tubes if properly loaded. R281.71. Quartz. Quartz Crystal Radio News. Jan. 1926, pp. 952 ff. Control. "Quartz Crystals Control Wavelengths of Broadcasting Stations," S. R. Winters and f. F. Byrnes. The use of quartz crystals in the control of frequencies in broadcasting stations is growing, as is evidenced by the decision of the Westinghquse Company, and the General Electric Company, i. e., to equip all of their stations with this piezoelectric mineral, according to the authors. Its properties, operation in circuits, the use of harmonics produced by such an oscillating crystal, methods of mounting, and results obtained by the Navy and others, indicate that the quartz crystal will be in general use among transmitting stations before long. R402. Short-Wave Systems. High Frequency Radio News. Jan. 1926, pp. 954ft. Systems. "Navy Investigates Ultra Frequencies," Dr. A. Hoyt Taylor. The investigation carried on by the Naval Research Laboratory with ultra frequencies is presented in graphic and systematic form. Night and day range, comparison of phenomena at various frequencies, and directional effects, show that certain bands of frequencies should be chosen for definite transmission schedules depending upon time, distance, and season. (NSUKNE No matter what circuit you are building, the final results will be better if you select Insuline for the panel — the material chosen by Radio Broadcast Engineers for the "Universal." Laboratory tests prove Insuline to be highest in dielectric strength and other properties conducive to clear reception. Also the most easily worked panel material. Doesn't chip or crack. Doesn't warp. Holds its lustre for all time. Insuline Panel for the "Universal," engraved by our exclusive Etch-O-Gravure Method, in gold and white or combination; drilled ready to set up: black or mahogany $3.50; "Frieze" finish, $4.00. Insuline panels, drilled and decorated, are furnished for all popular circuits. Also supplied in all standard sizeblanks. Insuline Sub-panels, drilled and mounted with metal sockets for UV and UX tubes for all circuits. Bakelite Brackets for Sub-panel mounting, etc., etc. If your dealer can't supply you write us direct. Send to-day for Free Booklet and price list. pumulfmr "Sets that Jack and Dad Built,' a practical 50-page book for building the most popular circuits, with diagrams and instructions for hook-up, sent for 25 cents to cover cost of mailing and postage. branches in Trincipal Cities ;ULATING COMPANY ofAME. (radio panel &-parts corp.) Insuline Bldg., 59 warren street NEW YORK Why not subscribe to Radio Broadcast? By the year only $4.00; or two years $6.00, saving $2.40. Send direct to Doubleday, Page 8s Company, Garden City, New York. Become a big-pay man in the greatest industry of all time. 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