Schedule of W3XAL

Radio Record, Volume IV, Issue 42, 1 May 1931, Page 29

Schedule of W3XAL

Description of Plant THE short-wave experimental broadcasting station of the Radio Corporation of America, W3XAL, managed and operated by the National Broadcasting Co., is located in the transmit‘ting building of WJZ at Bound Brook, New Jersey, and has to date trans- . mitted the programmes of this station. whe working frequency of W8XAL is 6700. ke, or 49.18 metres, and power input to the antenna ranges from 12 to 15 kw. Regular hours of operation are from 5.00 p.m. to 6.00 p.m. (Sunday from 5.0 p.m. to 6.45 p.m.), and 11.00 p.m. to 1.00 am. E.S.T. (about 103 hours behind N.Z.T.) daily, although the transmitter is also frequently operated during other hours on programmes of special interest. _ The short-wave equipment consists of intermediate and power radio frequency amplifiers, modulator, speech . amplifiers, and radiating system, a \ brief description of which follows — * One of the four 3050 ke. quartz erystals with constant temperature regulation controls the frequency of- 5, 75, 250 and 500 watt intermediate radio frequency amplifiers, the 75 watt being a shield grid stage and acting

as buffer and frequency doubler. These stages in turn excite the grids of four 10 k.w. UV-854’s in a push-pull output stage, which is capable of delivering 20 k.w. to the antenna. Regeneration in the 250, 500 and 20 k.w. stages is prevented by proper neutralisation. Constant current, or Heising, modulation of the plate power to the power amplifier is provided by ten 10 k.w. UV-854’s in parallel, voice frequencies being supplied to the gride of these valves from 500 watt speech amplifiers, preceded by a 5 watt line amplifier. All audio valves are operated at values which will cause no distortion on peak modulation, : Plate power to the modulator and power amplifier is supplied by twelve 10 k.w. UV--855’s in a three phase, full wave circuit, two valves in parallel ‘on each half phase, and to the intermediate radio frequency amplifiers and Speech amplifiers by two 1 k.w. single phase, full wave rectifiers, employing UV-856’s. A similar rectifier supplies grid bias to all radio frequency valves. Filament current for all valves is obtained from a 23 k.w, 28 volt generator, with the exception of the speech ampliflers, which are supplied from storage batteries. : A half-wave vertical Hertz radiator is mounted on a 105 foot wooden mast, the lower end being one-quarter wavelength, or 38 feet, above ground. This is conductively conducted to-the output stage of the transmitter through a 700 foot double feed line. . Provision is made for antenna tuning and coupling adjustment,