Hallicrafters s-120 need help..
 

Hello,

I have an old Hallicrafters s-120 (made in 1966). I have been having trouble
with the volume control. Everytime that I turn the volume on about 1/8 way
there is a very high squealing coming out of the speaker. The question I am
asking is: What could be causing this problem? I've been told it's either
the speaker or the potentiometer. Any ideas?

Thanks for any input,
Bruno Hache

Bruno,
It sounds like one of the tubes is microphonic, that is acting like a
microphone to produce feedback. Turn the radio on and set the volume control to
just below where the squealing starts. Then, using the eraser end of a pencil,
lightly tap each tube. The microphonic one will respond to your tapping by
producing the squealing or other noise. Replace the tube that is causing the
problem. Hope this helps you, Mike KF6KXG