Radio Broadcast (May 1927-Apr 1928)

262-286 RADIO BROADCAST ADVERTISER Oil My NEW! The Shielded Grid Sixes Imagine a set that with a fifteen foot antenna in a Chicago suburb will bring in forty to fifty stations from Atlantic to Pacific, from Canada to Mexico with great volume. That's what Shielded Grid Sixes are guaranteed to do. Their sensitivity and selectivity is equal or superior to that of any T. R. F. receiver or super-heterodyne. The 630-LSG, the generally preferred loop model kit is priced $91.50 and the 630-SG, the antenna model kit is priced $97.00 — both unconditionally guaranteed to equal or out-perform any set you've ever heard. The coupon brings complete information. Universal All Wave Tuners A series of the snappiest, neatest, lowest priced radio receivers you have seen in many a long day. You can build almost anything you like around the basic one stage T. R. F. and regenerative detector kit. In standard models you will find complete four tube battery or socket powered sets, or two tube battery or socket powered sets ideal for use with power amplifiers. You can use dry cell, standard, A. C, or Shielded Grid Tubes. The All Wave Tuners cover all waves from 18 to 3000 meters with selectivity sufficient to step out in New York, Chicago or Los Angeles. Prices range from $16.00 for the 640 tuner essential kit containing all coils, condensers and R. F. choke, to $54.00 for the 644 A. C. four tube socket powered tuner kit, less the $32.50 complete ABC socket power supply. Write for details. A LITTLE smaller than the famous S-M 220 — taking up a little less room — lower in price — the Silver-Marshall 240 audio transformer is without question the "biggest buy" in the radio field today. Smaller than its famous bigger brother, the 240 nevertheless out-ranks every other transformer at anywhere near its price. Made only as SilverMarshall can make them, 240's give clear and natural tone — they will reproduce the high notes and the low notes in their true values. They are ideally suited to super-heterodyne circuits because of their high frequency cut-off which reduces heterodyne interference. That's why they were selected for the 45 K. C. Super — that's why you'll find them in the really good designs in almost any radio publication that you may pick up. The characteristics of the 240 are similar to those of the 220 — they have practically a flat curve from between 100 and 5000 cycles, and the 5000 cycle cut-off which keeps heterodyne squeals and other noises at a minimum. And 240's are ideal for bringing your older receiver up to 1928 standards of quality. The 240 audio sells for $6.00, and the 241 output at $5.00. Hard to beat at any price, they cannot be equalled at these prices. 45 K.C. S Because a receiver can never be better than its power supply and because the finest was demanded in power units for the 45 K. C, A. C. Super-Heterodyne, Silver-Marshall parts were chosen by the designer. A 329 power transformer is used having two 200 volt secondaries, one 105-120, 60 cycle primary and one 5 volt filament winding, center tapped. It is rated at 85 milliamperes continuous duty without heating. Price $9.00. The S-M 331 Unichoke is a combined selective and brute force filter choke, the filtration of which when properly used is superior to that of other standard power supply filters and using less condenser capacity! Its tuned section eliminates the 120 cycle ripple and with only 7 mfd. condenser capacity the Unichoke's performance is equal or superior to two section chokes with from 8 to 12 mfd. condenser capacity! Rated at 85 milliamperes continuous duty. Price $8.00. The 325 Step Down Transformer supplies all necessary filament current for the new A. C. tubes. It has a i| volt secondary of 12 ampere capacity, a i\ volt secondary of 12 ampere capacity and another winding furnishing 5 or 7! volts for the filaments of 112, 171 or 210 power tubes. Price $8.00. 838-C West Jackson Blvd. Chicago, U. S. A. This coupon will bring ■ r „ . V . , ° SILVER-MARSHALL, Inc. yOU full information a bOUt j 838-C West Jackson Blvd., Chicago Tedl audlO amplification, 1 enclose 10c for which please send me full information on quality 1 I audio amplification, power supply equipment, the new Shielded Grid I power Supply equipment, Sixes and Universal All Wave Tuners. | the new Shielded Grid I I enclose i5c for complete instructions and blue prints for the i . Ail ■ Shielded Grid Sixes. I Sixes and Universal All I enclose 25c for instructions and blue prints for building the All | Wave Tuners. Blue prints on the All Wave j Name | Tuners and Shielded Grid Sixes 1 .,, .... , | Address ! are available at 25c each. Radio Bboadcast. February, 1S2S. Published monthly Vol XII No. 4. Published at Garden City, N. Y. Subscription price $4.00 a year. Garden City, N. Y., as second class mail matter. Doubleday, Doran & Company, Inc., Garden City, N. \. Entered at the post office at