National HRO 500 Communications Receiver Video #4 - Where are the Signals?

I continue exploring the radio's operation and arrive at a new, probably wrong, conclusion.

[@jimmiller9330]

Couple of things. Some old radios have a mute terminal that can be switched by a relay when going from receive to transmit. The radio may be in the mute state. Second, I would try a signal injector or signal generator to inject a sine wave at various points. Starting from the audio input to the audio amplifier and working backwards in the chain. Inject an audio tone at the volume control middle pin . You should hear a tone in the speaker or headphones. If you don’t, then that stage is your problem. Then you could use a signal generator to inject a tone modulated signal at prior stages. Keep working backwards until you locate the fault.

[@lammjame]

Jim, I appreciate you putting out these videos day in and day out. They make me feel like I'm right there beside you learning your thought process. Thanks for doing it.