Radio Broadcast (Nov. 1925-Apr 1926)

702 RADIO BROADCAST ADVERTISER Send /or this Ttew Hookup Four -Tube The outstanding receiver development of the season, in which is combined the genius of two of the most distinguished radio engineers. A receiver for the home builder that will represent for several seasons to come a far greater value than any other design available. Several outstanding features place the design in a position far in advance of anything available or contemplated. Unlimited wavelength range, with interchangeable antenna and detector coils; marvelously improved audio transformers; a special self-contained wiring harness; but one tuning or station selector control, are special features. Over-all design is rugged and solid. Adapted to practically any standard cabinet, any standard tube, any battery or eliminator source of supply, outdoor antenna or loop. Only a screw driver and pair of pliers necessary. The set can be built at an extremely low cost and parts are readily available at all radio dealers. Represented Manufacturers: Belden Mfg. Co. — S-C Wiring Harness Central Radio Laboratories — Centralab Resistance Polymet Mfg. Corporation — Fixed Condensers, Leak, and Leak Clips Poster & Co. — Drilled and Processed Front Panel and Drilled Sub-Panel Silver-Marshall, Inc. — Variable Condensers, Coil Sockets, Coils, Tube Sockets, Vernier Dial, Mounting Brackets Thordarson Elec. Mfg. Co.— £200 Power Transformers Yaxley Mfg. Co. — Rheostat, Jacks, Switch Get the hand-book at your radio dealer's, or clip the coupon and send 25 cents to S-C MERCHANDISING 65 E. Jackson Blvd. Chicago S-C Merchandising Company 65 E. Jackson Blvd., Chicago Herewith please find 25 cents for which send me the hand-book of the new S-C Four-Tube Receiver Name . . Address a Now, I Have Found Department for the Exchange of Ideas and Suggesof Value to the Radio Constructor and Operator eONTRI BUTIONS to this department are welcome and those used will be paid for at the usual rates, that is, from two to ten dollars each. A pri^e of twenty-five dollars is given for the best idea used during each three-month period. The prizewinner for the last period was announced in the February Radio Broadcast. Manuscripts intended for this department should not exceed about three hundred words in length, and should be typewritten. Little consideration can be given to manuscripts not typewritten. Envelopes should be addressed to this department, Radio Broadcast, Garden City, New York. BETTER. REPRODUCTION IN CONE SPEAKERS AN EASY way to eliminate the jingle L\ in the high notes and reproduce -t V the bass notes more faithfully in a cone loud speaker, taking as an example the Western Electric No. 540 AW, is as follows: Loosen the set screw in front which holds the pin, then remove the screws in the back thus allowing the metal ring, fibre ring, and screen to be removed. This exposes the telephone unit held to the frame by three screws. First, mark the frame where the unit is held to it so that it can be put back in the same place, and then remove the screws and carefully lift out the unit. Remove the screw holding the pin to its support and insert a piece of electric tape between these two members, first making a hole through the tape for the screw to go through. Replace the screw. Then slip over the pin a rubber tube | inch or more in thickness reaching from the base of the pin to just short of the parchment, and having its bore slightly smaller than that of the pin, so as to grip it tightly. With the use of this system, the possibility of bending or otherwise injuring the pin by loading it with rubber tape is avoided. See Fig. 1. /Angle HOW TO PROVIDE A COUNTERPOISE SYSTEM THOSE who use the Roberts or Browning-Drake circuits and are troubled with broad tuning antenna couplers, might well use the single inductance with a conductively coupled antenna, placing the antenna tap about one third up FIG. I Re-assemble, taking care to have the pin straight and to put the telephone unit back in the same place on the frame as marked. Tighten the screw in front to the pin. Before replacing the screen, tune in on some good station and test out the speaker. If there is any jingle leave the set screw in front secured to the pin, loosen up the screws holding the telephone unit to the frame, and move the unit until the jingle disappears and the best reproduction is obtained. Then tighten up the screws. Replace the screen and rings, thoroughly tightening up all screws. William C. Morrill, E. E. New York. tIt Tested and approved by Radio Broadcast Vk' from the filament end of the inductance, and grounding the negative A battery line. For those who have the space or who live in shingled houses, the substitution of a counterpoise for a ground (entirely eliminating the ground will materially sharpen the tuning and in my case was found to produce much clearer signals, with greater intensity, than with the ground. The lower edge of the shingles generally stops about 3 feet from the ground and overhangs the foundation wall by several inches. Small insulated screw eyes placed under the shingle-overhang all the way around the house will hold a good counterpoise. If the shingles go all the way to the ground, a row of screw eyes about the height of the doorways will work almost as good. See Fig. 2. My antenna combination is now an 80foot antenna and a 100-foot counterpoise. J. B. Greenman, Montclair, New Jersey. SOME NOTES ON SILVER'S MODEL 1926 RECEIVER WITH CHOKE AMPLIFICATION VARIATIONS on the theme of McMurdo Silver's "Model 1926 Broadcast Receiver," introduced to its readers in the November, 1925, number of Radio Broadcast, were presented by E. R. Pfaff in the January, 1926, number. Before the appearance of the latter article, the writer had constructed a receiver of this type using Thordarson Autoformer audio amplification. As the set was constructed for experimental purposes, and this circuit is peculiarly adapted to this end, one or two wrinkles used may be of interest. As described, the set has no binding