Radio Digest (Oct 1923-July 1924)

RADIO DIGEST — Illustrated February 16, lQtk YORK EXPERT LINKS TWO SUPERS CONNECTS HETERODYNE TO SUPER-REGENERATOR George Eltz Tells Result of Experiment to Get Best from Both Famous Circuits NEW YORK. — "Combining: the SuperHeterodyne and Super-Regenerative Receivers," was the talk iri\eii by George Of the Manhattan Electric Company at the last meeting of the Radio Club two hook-ups are the work of E. H. Armstrong, also patentee of the regenerative circuit, who was present at the meeting. Each circuit has its advantages and faults and Mr. Eltz explained his attempts to combine the desirable features of each without its disadvantages. The superheterodyne has remarkable selectivity and tivity; the super-regenerative ^has tremendous volume and sensitivity. The former requires from six to nine tubes; the latter is noisy. "It Works," but Kot Perfect Yet The circuit shown herewith is the outcome of Mr. Eltz' experiments to date. It works, although its designer admits it is still far from perfect. It is presented here in order that other experimenters who Navy's Cape May Plant Up for Highest Bidder WASHINGTON. — The navy recently ofsd its abandoned Radio station at Cape N. J., for sale to the highest bidder. The bids had to "cover" buildings, equipment, etc., but not the land. The transmitting set was a V2 kilowatt with all accessories. Two receiving sets were included in the material for sale. RAd'mdyNE "The Voice of the Nation" NO LOOPS NO ANTENNA THE RADIODYNE is operated by simply grounding to a water pipe or radiator, and throwing a few feet of wire on the floor. Uses any standard tubes — dry cell or storage battery. Extremely selective. Simple to operate — only two controls. Stations within a radius of 2000 miles can be picked up on the loud speaker ; any wave length from 200 to 700 meters. You can select the best programs with the Radiodyne. PRICE $150.00 For use in apartments, boats, automobiles, railroad trains, etc., the RADIODYNE is enjoyable where other receiving sets would not be practical. When interference, strays, static, etc., make other types of reception utterly useless, the RADIODYNE picks up broadcast programs clear and distinct. Write for illustrated folder which describes the RADIODYNE in detail. Every radio fan will be interested in this new type (antennaless) receiving set. Western Coil & Electrical Co. 312 5th St. NEW SUPER-REGENERATIVE-HETERODYNE HOOK-UP <T> (Tt AUDIO ly^<£ T*ANSRDR»Efc While not recommended for the average B. C. L., the above circuit may be interesting to the fans who have progressed to die stage of research. For those dyed-in-the-wool parts buyers, the constants are given as Mr. Eltz found them to be in his case. "Cut-and-try" is the only rule for success here. The constants are: Capacities, (1) .0005 mfd., (2) .00025 mfd., (3) .0005 mid., (4) 0.1 mfd., (5) .0005 mfd., (C) 0.5 mfd., (7) .01 mfd., (8) .0005 mfd., (9) .005 mfd., (10) 0.5 mfd., (11) .002 mfd., (12) .004 mfd., (13) .002 mfd.; Inductances, (A) 40 turns No. 30 on 2" tube, (B) 3* turns No. 30 on 3" tube, (C) 43 turns No. 30 on 3" tube tapped at 15 and 31 turns, (D) 35 turns, (E) 21 turns, (F) 88 turns, (G) 1500turn honeycomb, (H) 1253-tum honeycomb, (I) 2.28 Henries (approximately), (J) 2.28 Henries (approximately). care to do so may work to develop It. The reader will note that the hook-up Is divided by dot and dash lines into three parts. At the left is the oscillator and "first detector" of a super-heterodyne, in the center is a two-tube super-regenerative. To the right is the filter necessary to take out the high pitch whistle, developed within but essential to, the superregenerative. Shielding is necessary, as is careful placing of the parts to avoid undesirable capacity and inter-magnetic effects. As Mr. Armstrong stated in some remarks, after Mr. Eltz had finished. "Pre-determined sizes and calculations count for little when building such a set. Only the cut and try, build and rebuild method will get results," so every fan has an equal chance with the Radio engineer and mathematician. Racine, Wisconsin -(Ql&mwvn/ KNOCKDOWN NEUTRODYNE RECEIVER Unassembled Model KD-SO, Freed-Eisemonn Neutrodyne Receiver NOW the opportunity is presented to obtain a complete set of parts, recommended by the manufacturer, to work with each other in building your Neutrodyne set. An illustrated 32-page book on how to build the Neutrodyne with full-sized diagrams and templates included. Complete with Full Instructions NEUTRODYNE has taken the country by storm. It is the remarkable distance getting, powerful, non-oscillating and nonwhistling receiver. A 32-page book answers every question. The panel is accurately drilled. A baseboard is furnished ; in fact, everything down to the very last screw and nut, including all necessary parts excepting the cabinet. Besides the book there is furnished schematic blueprints and template for drilling the baseboard, also full-size pictorial perspective wiring diagram, so' that it will hardly be possible for the amateur with ordinary care and skill to make an error. Remember that here are licensed parts — not a collection of apparatus trusting to luck that they will assemble properly. Each part is designed and fitted to work with each other part in this particular set. The instructions are so complete and the parts so accurately matched that you will be grateful for the manner in which we have eliminated guesswork in the amateur construction of this receiver. For sale by dealers of the better class throughout the country, for amateur and experimental building. Builders are cautioned against attempting to build a Neutrodyne Set with parts which are not recommended and designed by the manufacturer to work with each other. ftca-ascrv** Rwe Cc*»o*»» $80 Dealers Write for Name of Nearest Distributer ^§8te»l UCENSED«T^ 32-page illustrated book of instructions on "How to Build the Neutrodyne" with full sise pictorial wiring diagram and fullsize panel and baseboard templates, $1. At your Radio Dealers. Front View KD-50, Neutrodyne Being Assembled SPERRY BUILDING MANHATTAN BRIDGE PLAZA BROOKLYN, N. Y.