37-116, Alignment of 18 MC band, LO instability - 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: 37-116, Alignment of 18 MC band, LO instability (/showthread.php?tid=2507)

---

37-116, Alignment of 18 MC band, LO instability - spfradios2 - 07-27-2010

I just completed my alignment of the 37-116. I thought I'd pass on my experience with an instability issue on the high freq band.

On the 18 MC band, I first attempted to follow the instructions for alignment by seeking the second peak on the 18 MC compensator (43D). It did not work. The local oscillator totally broke down and went crazy higher than 16 MC. At first I thought, maybe a bad component in the oscillator section, or a poorly dressed wire. But that was not it.

The problem was due to the setting of the low end of the band at 12 MC (43E). Since I did a major overhaul, the settings of the compensators was way out of wack. I found that I had to adjust the low end first, then set a mid range point at 15 MC, a point where the oscillator was still working. I then had to cycle back and forth several times, resetting the 12 MC and 15 MC until the adjustments stablilized (no changes needed). Then I could go high and adjust at 18 MC, which really did not need much change. Also, I did not have any problem with the other bands, nor the compensators for the antennae and RF sections.

This issue may not occur on a chassis that has not been "messed around with", or where the low end compensator was not modified.

John

---

Re: 37-116, Alignment of 18 MC band, LO instability - Ron Ramirez - 07-27-2010

John - thanks for sharing. This info should come in handy for everyone.

---