10-15-2005, 06:30 PM
You actually have a Model 504 then Chuck, according to Service Bulletin No. 176-A, November, 1933.
Alignment, yep. If all tube voltages are "in the park" for the RF and IF sections, it sounds like you need it. Also check the tube voltages on the detector area as well. All tubes check ok, I assume? A funky DET tube can cause distortion, which will mess around with the AVC then as well causing wierd RF/IF gain things that cause a sort of feedback loop on itself.
I'd do a good full alignment first to see if it improves - it can't hurt. If you have not done it, then it needs it anyway, especially if you have done a wholesale parts replacement.
Alignment, yep. If all tube voltages are "in the park" for the RF and IF sections, it sounds like you need it. Also check the tube voltages on the detector area as well. All tubes check ok, I assume? A funky DET tube can cause distortion, which will mess around with the AVC then as well causing wierd RF/IF gain things that cause a sort of feedback loop on itself.
I'd do a good full alignment first to see if it improves - it can't hurt. If you have not done it, then it needs it anyway, especially if you have done a wholesale parts replacement.
Chuck Schwark,
The Philco Repair Bench
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