Quote:
Originally Posted by vortalexfan
No there is no change in the AVC voltage when trying to tune in a known local station. In fact trying to tune anywhere on the dial the AVC voltage stays pretty constant at around positive 15 mV and doesn't go negative at any point when tuning across the dial with just a long wire antenna attached.
It does however work when using the signal generator but like I said previously I have to use my signal generator's unattenuated high volume output signal output in order for the radio to be able to pick up the signal from the signal generator and be able to affect the AVC voltage.
So I'm not sure what's going on here.
Did you see the video I posted of my radio and what it's doing with just an antenna hooked up?
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What you say indicates is that your local oscillator is either not running, or it's running at an incorrect frequency.
When you inject an IF frequency from you signal generator you are forcing the correct signal through the IF transformes, which in turn gets detected by the 30 tube and produces AVC voltage. The key here is you're not relying on the local oscillator to mix with the incoming rf signal to produce that outcome.
In normal operation the rf signal mixes with the local oscillator to create beat frequencies equal to the sum and difference of the two. One of those beat frequencies is the IF signal. You should double check that you didn't replace a cap around the 1C6 tuned circuit with a incorrect value and also verify the two winding's in the oscillator coil(#17484) have continuity.