01-24-2022, 01:05 PM
Here are some things to check:
Do you have audio? Do you get a hum in the speaker if you touch the top cap of the 75 tube.
If not, do you have plate voltage on the 42 output tube? An open output transformer primary would cause no plate voltage and low power supply current draw.
If the audio system is ok, inject an IF signal at 460 kHz into the top cap of the 6A7. Do you hear the signal? If not problem in the IF stage.
If the IF is ok, check if the oscillator is working. Set the dial on the 60 to 600 and listen on a nearby portable radio for the osc signal at around 600 + 460 = 1060 kHz. If you don't hear it, there is still a problem with the oscillator coil or circuit.
Hope this helps.
Do you have audio? Do you get a hum in the speaker if you touch the top cap of the 75 tube.
If not, do you have plate voltage on the 42 output tube? An open output transformer primary would cause no plate voltage and low power supply current draw.
If the audio system is ok, inject an IF signal at 460 kHz into the top cap of the 6A7. Do you hear the signal? If not problem in the IF stage.
If the IF is ok, check if the oscillator is working. Set the dial on the 60 to 600 and listen on a nearby portable radio for the osc signal at around 600 + 460 = 1060 kHz. If you don't hear it, there is still a problem with the oscillator coil or circuit.
Hope this helps.
