Hi,

It sounds like you no longer have automatic gain control (AGC)action.
The AGC circuit should provide a negative voltage to the grids of the IF
amplifier tubes, to reduce their gain with strong signals.
Lack of AGC would lead to "blocking" which is as you describe.

73,
Ed Knobloch



Steven Burrows wrote:
snip
Recently, I got both chassis ready to try out. They both worked ok, but I
noticed a new problem on both radios that I didn't see on the first
restoration (new caps only). When I turn the RF gain pot up beyond
approximately 66% of full rotation clockwise, the radio sensitivity drops
significantly and no stations or normal static can be heard. When I back off
on the gain control, the radio returns to normal. I am guessing that this
sympton (observed on bot radios) is from RF amplifier overload. Is this
behavior normal for a tube radio, and is there a fix? These are the first
boatanchors that I have ever tried to work on, so all of this is a new
experience to me. In all cases, I had the radio hooked up to a 100 ft.
random longwire antenna.

If this behaviour is a symptom on a goof-up on my part in rewiring the sets,
I would appreciate some advice on how to fix the problem.

Steve Burrows