BITX Build Updat #4 VFO Stability

I wasn't quite satisfied with the long-term stability of my VFO.  It seemed like it was drifting about 70 Hz per hour, even after the initial warm-up period.   So, all out of Q-Dope, I went to the local pharmacy in search of clear nail-polish.  (My family was making fun of me.)   I got home and applied several coats of "Sally Hansen No Chip Top Coat Vernis de Protection."   I let it dry a bit, then started watching the frequency counter.  At first results were disappointing.   Drift continued.  Now it seemed to be drifting up!   I cracked the books.  EMRFD has a good chapter on temperature compensation of VFOs, but the process seemed painful.    I wasn't looking forward to it.

I left the VFO on when I went to work, noting the freq as I departed.   Ten hours later I returned, and was delighted to find the frequency almost exactly where I left it!  It may have taken a while for the nail polish to completely dry.    I'll leave it running again today to see how it does.


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