[R-390] VFO Temp Compensation update

[David Wise]

It goes very slowly, interspersed with other activities.
I found some time ago that my VFO's f/T curve is
third order, meaning it goes up, then down, then
up again.  A typical set of deltas is +50 (1st hour),
-100 (hours 1 through 4), +50 (hours 4-12).  I have
a frequency counter on my SE-3's PLL, a clock, and
a thermometer.  I aim a video camera at the readouts,
slip a big tape into the attached VCR, and go away.
Six hours later the tape's full, and I just take one
more manual reading the next morning.

If anybody else has charted their radio's drift,
I'd like to compare notes.

I've reduced my expectations.  Now I'm trying
to flatten the middle part by choosing compensation
caps.  Once I have it about right, I'll sort of flatten
the first part by manipulating filament current.  This
will only track if the set is turned on from stone
cold, but that's the usual regime at my house, so it's
not as special-case as it sounds.  To heck with the third
part, that's about 10 cycles/hour.  If I can't
keep up with that, I must be dead :-)

Regards,
Dave Wise