No subject

Fri Oct 9 21:52:43 UTC 2009

5 ppb. If settability is not specified, it can be estimated from the tune
range and the number of turns of the adjusting device.  A rule of thumb is
to use one point of resolution for every three degrees of rotation.  The
10811 has +/- 10 Hz minimum - assuming they threw in some margin - 30 Hz
total range with 18 turns gives  1.4 ppb - you're doing quite well with 0.25
But, of course the OCXO is probably aging 0.5 ppb/day...........

On Fri, Nov 13, 2009 at 12:59 AM, Glenn Little WB4UIV <
glennmaillist at> wrote:

> I just got a system that allows me to compare the phase difference between
> a reference and an external oscillator.
> I am using a Vectron oscillator installed in a  HP 5345A counter as the
> external oscillator and a PTB-100 as the reference.
> How close to the reference should I be able to set the OCXO?
> After a 3 day warm up, it appears that I have gotten the OCXO to within
> 0.0025 Hz of the Rubidium reference.
> I am checking with a strip chart recorder over a three hour period for the
> next few days to see if the OCXO stays at this accuracy.
> Is it really possible to set an OCXO this close or have I made some errors
> in my computation of frequency offset?
> Thanks
> 73
> Glenn
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