Note
QST, Nov 1970, p. 131.
Good inside photo: QST, Jan 1971, p. 133.
Specs: QST, Jul 1971, p. 160.
QST, Aug 1971, p. 127. (inside photos of both)
The Alpha Seventy is a high-power linear amplifier that incorporates many major state-of-the-art advances in design. It will operate at maximum legal power in any mode with a 100% duty cycle.
Features include the use of quiet vapor-phase cooling (no high-velocity fans) and vacuum sealed transmit-receive relays. With vapor-cooling its Eimac 3CV1500A7 tube reaches only 100'ºC under full load, not 200ºC like most air-cooled tubes. Heat is expelled through the rear of the cabinet, away from the operator and other equipment.
Other features of the Alpha Seventy include a built-in MOSFET electronic T/R switch that is pre-selected on receive by the extremely high unloaded Q of the plate tank circuit, cutoff bias that is electronically controlled to prevent plate current flow in the absence of RF drive, DC coupled ALC output that simplifies tuneup, and provision for later installation of an accessory to provide remote-control or automatic band change, tuning and loading.
The Alpha Seventy covers all amateur bands from 80 through 10 meters, with an optional extension kit for 160 meters.
Drive requirements are 100 watts PEP nominal for 2.5 kW PEP plate input; 50 watts nominal for 1 kW carrier input.
Third-order products are more than 30 dB below each of two equal test
tones at 2.5 kW PEP input.