Radio Broadcast (May 1928-Apr 1929)

RADIO BROADCAST ADVERTISER 173 Short Wwe Set/ Public Address Amplifier/ "Round the World Four" fl9 WW A ND now — an entirely new type of short wave receiver is ready, "''^flw /\ incorporating all of the sound engineering principles and n advanced developments that have made S M the most pop ■ ular quality parts today. Heralding Silver-Marshall's definite entry into the short wave field, the new "Round the World Four" and "Round the World Adapter" introduce advanced features and an entirely new design technique. This set, the first to include screen grid R. F. amplification with one-dial tuning for a range of 17.4 to 204 meters, is simply irresistible. Completely shielded in a thick aluminum cabinet, it can be had as a two-tube tuner to adapt any standard set to short wave reception, or as a complete 4-tube set with loud speaker range of half way round the world and back. These new S-M short wave sets are the first to be offered designed especially for broadcast and phone reception primarily, and for code secondarily. They alone have the smooth regeneration control that provides the enormous sensitivity necessary to long distance voice and music reception — yet they are absolutely non-radiating. If you're after the thrill of real, world-wide DX, the "Round the World Four" is the set for you. Amateur station 9VS reported loud-speaker reception from six continents in an evening. Station 9BBW, operating the set, conducted amateur two-way communication with Germany, France, England, and Italy in one evening. In daylight, east and west coast amateur stations are heard in Chicago — Nauen, Germany, and England come in like locals. Five, ten, fifteen, and fifty-watt amateur telephones all over America and Canada are regular reception on the "Round the World Four." Type 730 "Round the World Four" kit, ready to assemble, including all parts and cabinet just as illustrated, is $51.00. Type 731 is the two-tube "Round the World Adapter" kit, to adapt any broadcast set to long distance short wave reception, and is priced at $36.00 complete, with identical aluminum cabinet. Price, 131T, -U, -V. and -W. coils, tuning from 17.4 to 204 meters, $1.25 each, or $5.75 for set of four plug-in coils with 512 socket. Type 130 winding forms cost but 50 cents each. Type 732 "Round the World" essential kit includes all above coils, coil socket, .00014 tuning condenser, .00035 tickler condenser, and three R. F. choke coils, with complete instructions, $16.50. 685 Public Address Unipac THE S-M type 685 Public Address Unipac is a high power socket-power amplifier that can be heard by from 2,000 to 30,000 people at once. It will operate one to twelve loud speakers and can be used interchangeably for voice, phonograph record or radio amplification. Good electrically cut symphony orchestra or jazz band records will be reproduced at volume equal to or greater than original, and with tone both natural and perfect. Using the microphone, clear, understandable announcements or speeches can be made to crowds of 5,000 to 10,000 people, either indoors or outdoors. Record or radio music can be heard half a mile away on clear days. Type 685 Unipac fills a long-felt want for an economical portable or permanent public address amplifier. It is complete in itself, requiring only one UX226, one UY227, one UX250, and two UX281 tubes and connection to a 110 volt, 60 cycle lamp socket for operation. Any speakers may be used, with any microphone, radio set, or magnetic record pick-up. With political conventions, sporting events and elections coming on, for the wide-awake experimenter there is a wide and profitable market, both in sale and rental, to conventions, lodges, clubs, theatres, schools, churches, amusement parks, dance halls, and many other places. For thoroughly high quality outdoor demonstrations the 685 Unipac has no equal. (685 Unipac is not suited to nor intended for home use.) Price, factory assembled, ready to use, less tubes and accessories, $160.00. Type 685 Kit, ready to assemble, with complete instructions, is priced at $124.00. SILVER -MARSHALL, Inc. 870 W. Jackson Blvd., CHICAGO, U. S. A. For 6c in stamps, complete constructional data sheets will be mailed.