07-31-2024, 10:00 PM
Sound like you've got the sensitivity up too high causing the detector to start oscillating. When it's oscillating it oscillate when it is turn across an am signal. This is what causes that tunable squeal that you are hearing. It's #18 the one with fiber nut on it. Back it out a turn or two and that should calm it down. This does not adjust the IF frequency but control the feedback in the detector circuit.
The fiber nut is easily broken never tighten it down it will crack. If the set is work right it doesn't need to be tight at all.
It is important to do the IF alignment for gain and selectivity. I noted two different fq 450kc & 460kc listed. I would probably pick 460kc that's a much more popular Philco fq, I can't think of any that use 450kc.
Once you get the IF peaked up then adjust the sensitivity just below the point of oscillation.
The fiber nut is easily broken never tighten it down it will crack. If the set is work right it doesn't need to be tight at all.
It is important to do the IF alignment for gain and selectivity. I noted two different fq 450kc & 460kc listed. I would probably pick 460kc that's a much more popular Philco fq, I can't think of any that use 450kc.
Once you get the IF peaked up then adjust the sensitivity just below the point of oscillation.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got it!
Terry
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