[time-nuts] HP5065A C-field current is temperature sensitive

Poul-Henning Kamp phk at phk.freebsd.dk
Sat Aug 29 15:33:11 EDT 2015

In message <8BE4F2B1-171B-4117-88A5-A6DC64D9890D at n1k.org>, Bob Camp writes:

>Most potentiometers have very good TC when used in a “ratio mode”. 
>You can quickly mess that up by putting resistance in series with
>the pot. It’s a bit surprising how may times you see this inherent stability
>messed up that way.

Yes, but they do have a good reason for it here:  They want the
C-field pot to be "calibrated" in frequency so they need the
resulting voltage to follow the quadratic C-field sensitivity
decently well.

I still havn't figured out what component is responsible for the
huge tempco, but it is not the C-field pot.  There's a few PPM
there but not that many.

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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