[bridkarl]

Not specifically a Philco question, but I expect to see this again so maybe someone can explain.
In this schematic I see an .005 cap going back to the speaker coil - red line. I assume the purpose is to complete the audio circuit by biasing the grid screen on the 6V6 audio output tube.

This radio hasn’t had this cap installed so I have a severe motorboating problem. Given this is a field coil speaker setup that means  as it’s part of the power supply this could be the source of the B+ issue causing the motorboating???  Basically the 6V6 hasn’t been biased correctly.

Or am  I totally misunderstanding ??