Quote:
Originally Posted by init4fun
The reason is that your detector tube , which should be a #27 if I looked at the right schematic , is an indirectly heated cathode type of tube , whereas your #80 B+ rectifier and #71A audio output tubes are directly heated cathodes . When you turn the power on the directly heated cathode tubes are conducting pretty much instantly VS the one indirectly heated cathode taking it's sweet time to begin passing signal . For all that time you have the audio amp section operating wide open but with no signal to process . In the absence of signal to force a bit of bias onto the circuit the tubes become very sensitive to "Microphonics" , having loose elements in the tube actually rattle and give off squeals . This is of course assuming that you did a full recap on the radio (haven't kept up with the entire thread here) because an electrical cause could be if the capacitor listed on the schematic as "43 - By pass condenser .002 mfd." were bad that could cause the amp to squeal till the detector warmed up and began supplying it with audio as well .
|
I did not replace any of the bypass caps just the filter caps, and that's how it operates.
No. 43 the .002 MFD Cap is a mica cap so I didn't even bother with that cap.