[time-nuts] Man with too many clocks.

Wes wes at triconet.org
Fri Nov 4 16:35:08 EDT 2016


On 11/4/2016 12:34 PM, Hal Murray wrote:
> kb8tq at n1k.org said:
>> The only practical way to set the 10811 or 10544 is with a >= 10 turn pot on
>> the EFC. I never have worked out just why there are so many instruments that
>> don’t have a pot on the EFC.
> How would temperature effect that?  For that matter, how does temperature
> effect the typical mechanical capacitor?  Does anybody play fancy tricks to
> cancel out the mechanical motions?  (like the mercury pendulum - as the
> pendulum rod expands the mercury expands in the other direction to keep the
> CG the same)
>
The variable tuning capacitor in one of the military "frequency meters" (I 
forget which one, BC221 leaps to mind) had a small disk on an adjustment screw 
that worked against a bi-metallic strip "diving board" to make a temperature 
sensitive trimmer capacitor.  I suspect, however, that it functioned more to 
compensate the inductor than the variable capacitor that was very robust.

Before synthesizers, I built a VFO for a homemade receiver using one of these 
cannibalized from a freq meter.

Wes Stewart, N7WS


More information about the time-nuts mailing list