63 thunderbird radio knob use
i purchased a 63 t-bird am radio that works great, i have it hooked up on the work bench to test it, but need to know the following; two questions please.
1. the left outer knob turns the radio on/off and adjusts volume, this works good,i don't know what the inner knob dose- it turns and clicks into three spots, but i don't hear anything change. can you tell me what it dose.
2. i noticed when the radio is on that the power transistor on the top rear of the radio gets hot and the top front power transistor dose not, is this normal.
i want to make sure everything is ok with the radio before i put it into the car.
thanks as always,