[time-nuts] Man with too many clocks.

Bob Camp kb8tq at n1k.org
Sat Nov 5 08:01:33 EDT 2016


HI

If you use a good wire wound pot and run it off of and oscillator EFC source (not
all have them), the temperature effect is pretty much zero. You are using the pot
as a ratio device. 

A mechanical cap that is part of the heated region of the OCXO (the normal case)
has already been taken into consideration when the OCXO set point is adjusted to
compensate it.

Bob

> On Nov 4, 2016, at 3:34 PM, Hal Murray <hmurray at megapathdsl.net> 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)
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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