[time-nuts] How Rubidiums make their frequency (was RE: time-nuts Digest, Vol 21, Issue 22)

Rex rexa at sonic.net
Thu Apr 20 05:55:37 EDT 2006

On Thu, 20 Apr 2006 02:31:08 -0700, "Christopher Hoover"
<ch at murgatroid.com> wrote:
>Hi Tom,
>That's a good explanation, thank you.   I got that much already.  (While it
>took some time for my phyiscs, chemistry and semiconductor physics studies
>to kick back in, it all clicked last week.)   The Tracor, indeed, seems
>fairly ordinary compared to the other Rb's I have, going by the test points
>and the various labels inside.   There is the typical synthesizer section,
>audio demodulation section for the photocell, etc.
>So what I'm really wondering is this: is there a  wear mechanism or failure
>mode in the physics package that might explain why I have to crank the mag
>field almost to its high limit to get 5 MHz?  (This question presumes the
>mag field control is working properly, and I cannot say for sure that it
>-- Christopher.

I could be way off, but are you sure the xtal osc is centered on the
desired range?

Having the adjustment procedure for your unit would be a good advantage.
I got an Efretom rubidium a few years back that would not lock. I went
through all the proceedures and found that the crystal had drifted out
of the lock range. I was able to get it working but at the limit of the
xtal trimmer. Had to change a fixed capacitor to get it back near the
mid of the xtal trimmer.

So, I'm thinking I might have got it locked by messing with C field if I
had a problem like this. Would have locked but off correct freq.

Not sure if this is a reasonable discussion, you may have this stuff all
understood. Do you have the full service documentation?

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