Philco 48-250 - Printable Version
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Philco 48-250 - MarkinK-zoo - 11-14-2020
Hi, all. So I recapped this set a while back and had all kinds of problems with whistles and stations coming in all over the dial. I went back through it today. I did an alignment and it's much better, but not right. 590 comes in well, but can be heard through much of the the lower end of the dial though quietly. 950 and 980 come in and it seems okay above there through the rest of the dial. The antenna trimmer doesn't really peak. tightened all the down it drops and as you back it off stations come in better, but it doesn't peak. The IFs peak. I used orange drops for all of the non-electrolytic caps and ceramic disks for C401 and C201. New electrolytics. Any ideas?
RE: Philco 48-250 - Radioroslyn - 11-14-2020
Sounds like you've got a problem with the loop ant. Not connected to the proper terminals.
RE: Philco 48-250 - MarkinK-zoo - 11-14-2020
I don't see how I could have connected the loop antenna incorrectly. One side connects to a terminal on top of the tuning gang and the other connects to a terminal nearby with a wire that goes inside the chassis. I followed it and it goes to the IF cans like the schematic shows. No other places to connect. The loop has continuity, so no broken wire in the loop.
RE: Philco 48-250 - Chas - 11-14-2020
Quote:MarkinK-zoo The antenna trimmer doesn't really peak.That is a sign there is a problem in associated circuits with that trimmer...
Do the circuit troubleshooting in that area with a conventional analog VOM.. Continuity with a DVM could be misleading. Most ANT/RF coils have a low resistance. Look for ground to chassis via rivets, solder them to the chassis using an active flux and an iron with a large copper bit (bolt)... GL chas