07-22-2022, 02:50 PM
I guess I was thrown off when you mentioned the IF so I honed in on that. And at first I had the earlier schematic. Yes, it is strange to have an IF wire coupling to the suppressor grid. This may be Philco doing an experiment with oscillation suppression or regeneration. I've seen 1940 models with the AVC tied to the suppressor grid but this looks like a feedback issue. Normally grid 3 is connected to the cathode.