Radio broadcast .. (1922-30)

I\ THE RADIO MARKETPLACE News, Useful Data, and Information on the Offerings of the Manufacturer Sonora Screen-Grid Set SONORA PHONOGRAPH COMPANY, INC.: The Sonora Model A-31 Screen-Grid Low-boy re- ceiver lists at $149.50. The set is of unit con- struction, being composed of three separate units; the r.f. amplifier and detector, the a. f. amplifier, and the power Supply with an electro- dynamic loud speaker. Any one of the three units may be removed readily for servicing. The set uses three screen-grid tubes and power detector followed by a single stage of a.f. ampli- fication and a push-pull power amplifier with two 245-type tubes. Zenith Model 53 ZENITH RADIO CORPORATION: This receiver uses a nine-tube chassis with the following features: automatic tuning, screen-grid tubes, double push-pull amplification, automatic volume control, and a large size electrodynamic loud speaker. The receiver lists at $275. Jack Horncr Speakers OPEHADIO MANUFACTURING COMPANY: Be- lieving that the next big step in radio will be remote control, this company is manufacturing an electrodynamic loud speaker in an artistic baffle designed to be hung from the molding. It is known as the Jack Homer model and it has an effective baffle length of 40 inches. It is made for operation on 110 volts 25-40 cycle, 110 volts 50-60 cycle, and 110 volt d.c. Temple D. C. Receiver TEMPLE CORPORATION: To meet the demand for a receiver designed for operation on 110 volts d.c. this company has produced a set using six 112A*s and four 17] \'s. It uses a fourteen-inch electrodynamic loud speaker and is available in two different models. New Connector Plug NATIONAL COMPANY: A semi-soft rubber cable connector plug has been developed to be .used as simple and effective method of connect- ing the chassis of an electrodynamic loud speaker field to a power pack. Webster Electric Pick-up WEBSTER ELECTRIC COMPANY: The new Webster pick-ups have the following features: low-inertia stylus bearing utilizing an all-metal pivoting action; small carefully balanced pick- up head giving a weight on the record of only 4} ounces; Cobalt steel magnet; shock-absorb- ing arm bearing with pivot at base; volume control incorporated in base. The pick-up is available in various models either with or with- out the tone arm or volume control. A pick-up designed especially for use with the Victor Radio, Model 32, lists at $19.50. New Tube Socket Designed CINCH MANUFACTUH NO CORPORATION: This company has designed a series of radio tube sockets. The sockets are constructed so as to give good contact and with accessible lugs for soldering. For years this company has been manufacturing fasteners for automobile manu- facturers. New Thermatrol Products THERMATROL MANUFACTURING COMPANY: The new Filtrol No. 460 is designed to eliminate interference that reaches a radio receiver through the a.c. lines. The unit contains a com- bination of inductance and capacity, and is con- nected between the light socket and the radio receiver. The Filtrol No. 458 is designed for connection directly to the apparatus producing interference. The Thermatron heavy-duty line voltage control No. 210 is designed to absorb excess line voltage. The device contains four separate outlets to take care of all usual line voltage variations. Capehart Automatic Phonograph CAPEHAHT AUTOMATIC PHONOGRAPH COR- PORATION: The Capehart Club Modej Orches- trope. No. 28-F, combines an automatic phono- graph with a three-stage power amplifier and an ejectrodynamic loudspeaker. I twill play twenty- eight records automatically on both sides at an operating cost of approximately two cents per hour (ten cents per kwh.). The dimensions of the cabinet are: height 111 inches, width 45 inches, and depth 23-i inches. The instrument is shipped as a complete unit and the tubes are packed in a box which it placed in the bottom of the cabinet. Portable Phonograph Q. R. S. De Vry Corporation: Five different types of portable phonographs are being made by this company. The Model 15 lists at $15, the Model 20 at $20, the Model 25A at $25, the Model 50 at $50, and the Model 375 at $37.50. Some models are designed for operation from the a.c. line and others derive their power from dry-cell batteries contained in the cabinet. Utona Loud Speakers r AMERICAN RADIO PRODUCTS CORPORATION: The electrodynamic loud speakers manufac- tured by this company are available in various models for either a c. or d.c. operation. RCA Theremin RADIO-VICTOR CORPORATION OF AMERICA: The Theremin is a musical instrument being manufactured under an option on the patent held by the inventor, Professor Leon Theremin. The instrument is operated by moving the hands relative to the loop bar which control the volume and the vertical rod which controls the pitch. The device is actually a beat-frequency oscillator whose output is controlled by the capacity coupling between the hands of the operator and the looped bar and the vertical rod. New Microphone RADIO RECEPTOR COMPANY: This company announces a new line of microphones for public- address and other sound-reproduction purposes. Although designed particularly for use with a Powerizer sound-amplifying system, they may be used satisfactorily with any well-designed amplifier. Three different types are made, a 3J- inch, a 6-inch, and a hand microphone. Utah Loud Speakers UTAH RADIO PRODUCTS COMPANY: The Model 66-A Stadium electrodynamic loud speaker was designed for 110-volt a.c, operation. The overall diameter is 12 J inches, the cone diameter being 10J inches. It is equipped with a full-wave high-voltage rectifier which operates directly from the a.c. line without any step- down transformers. The loud speaker can be used on either 25 or 60 cycles. The Grebe Synchrophase A. H. GREBE AND COMPANY: Features of the new Grebe receivers are three screen-grid tubes, band-pass filters, push-pull amplification, large diameter electrodynamic loud speaker, and automatic line voltage control. The set OSes six tuning condensers and contains a special phonograph pick-up input transformer so that modern high-quality low-impedance pick-up units may be used. 102 DECEMBER 1929 •