48-472-121 tracking problem - Printable Version
+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco Electronic Restoration (https://philcoradio.com/phorum/forumdisplay.php?fid=8)
+--- Thread: 48-472-121 tracking problem (/showthread.php?tid=26317)
+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco Electronic Restoration (https://philcoradio.com/phorum/forumdisplay.php?fid=8)
+--- Thread: 48-472-121 tracking problem (/showthread.php?tid=26317)
48-472-121 tracking problem - SlidesK - 03-02-2026
Hello, I’ve been working on restoring this radio for a long time and now that I’ve aligned the cans as specified I find a big tracking error from 550kc to 1200kc and would like to know if anyone else has dealt with this. Philco directions go from IF to the high side and I don’t find an obvious adjustment for midrange. I’m wondering if the transformer coil adjustment for am can be revisited after IF setting and used for a 600 kc padder of sorts to get the tracking slope that I need for the complete dial
I tried to attach the service info but couldn’t.
RE: 48-472-121 tracking problem - SlidesK - 03-06-2026
Looks like this post wasn’t understood sorry if it breaks rules so if it does I’m asking the moderator to please delete.
RE: 48-472-121 tracking problem - DaleHCook - 03-06-2026
When you were doing the alignment were you using:
1) Detectors set a maximum sensitivity
and
2) The lowest RF generator output which would produce a usable detector indication, repeatedly reducing the generator output to keep it at a minimum
Which RF generator were you using? Which detector were you using?
RE: 48-472-121 tracking problem - RodB - 03-06-2026
Hello SlidesK,
It took me a while to find a schematic I could read. It's in Rider's vol.18. The only adjustment for the AM Oscillator is C401b. You can try that adjustment at the setting of 600kHz and see if it gives you better tracking. About 75% of vintage radios have a separate adjustment padder for the lower end of the broadcast band. You may want to check the fixed mica caps in the oscillator circuit (12AU7 tube) for correct values and leakage. If one of those is off then it'll give your symptoms.