136 



BELL SYSTEM TECHNICAL JOURNAL 



and 11. It consists of six units: A power panel, a 10,000-volt rectifier 

 for the water-cooled tubes, a piezo-electric oscillator unit, an inter- 

 mediate amplifier unit, a power amplifier unit employing two 10-kw. 

 tubes, and an output unit. An air-cooled transformer for the rectifier, 

 the associated filter, and an artificial antenna are assembled in a 



Fig. 12 — -Western Electric 6-B (l-k\v.) radio transmitter. 



screened enclosure in the rear of the panels. Three motor-generator 

 sets are provided to supply filament power, grid bias, and plate power 

 for the air-cooled tubes. A 3-phase power input of 30 kw. at 220 

 volts is required. The equipment is capable of fidelity in trans- 

 mission comparable with that of the 50-kw. unit. The amplitude of 

 the harmonics radiated is held to approximately 0.2 per cent. 



A 1-kw. equipment of the same type is shown in Figs. 12 and 13. 

 It involves only two panels, a piezo-electric oscillator unit and an 

 amplifier unit. The final power stage employs a 4-kw. water-cooled 

 tube. Two motor generators are used, one supplying 24 volts and 



