I have a 1936 HRO that seems to have a distortion problem related to the avc circuit. It goes like this With the avc on on the rf gain at max a strong broadcast station will have some distortion. I can back off the rf gain control and it clears up the distortion.
This is what I've done, good set of tubes, align if and rf sections, replace paper/foil caps, check resistors for tolerance (all seem to be pretty good there are a couple in the avc circuit that are o/t but added parallel resistors to bring then into spec. Cleaned coils, switches, and sockets. HV supply is about 240vdc
Measured the avc voltage and with no signal it about -1 1/2 volts, good undistorted signal is around -5v and very strong signal is about -12. It seems to like voltages around from -1 1/2v to -7v above that distortion creeps in.
I tried loading the avc line down a little w/a high value resistor. This did drop the voltage down a little but made the distortion worst. Backing down the rf gain clears it up but it pegs the S meter unless the gain is up.
http://www.one-electron.com/doc_archive ... al_HRO.pdfSo is this the nature of the beast or am I missing something?
Tnx
Terry N3GTE