Umm, this is the small base amplifier with a toroid (doughnut) transformer in the rear.
Puts about 22 Volts on the RF transistors on standby. The tiny transformer drops it to 14 or 15 Volts under load.
Tends to blow out the 12-Volt MRF-455 parts.
Found that putting a 30-Amp automotive-type relay between the power supply and the RF transistors' collector circuit would protect the transistors from the destructively-high standby voltage. Keying it along with the antenna relay would connect the power only when the transistors are drawing current, and the voltage pulls down to a safe level. Beefing up the keying transistor to handle the current for two relay coils is a good idea, too.
Odds are 99 percent or more that the RF transistors are toast. That's what this model is famous for, along with exploding power-supply filter caps.
The other solution is to use more-expensive transistors rated for a 28-Volt power supply. The relay is cheaper.
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