[time-nuts] OCXO retrace, how long is reasonable?

[rfnuts]

Hi,

given it is a 10MHz OCXO, your drift is just 4E-11/hour or 9.6E-10/day, 
which isn't terribly bad, is it?

A good modern OCXO is specified at +/- 0.2ppb/day (2E-10) after 30 days 
of continuous operation. Some ultra high performance stuff does 
<1E-10/day, and may improve down into the E-11's after years of 
undisturbed operation.

Keep in mind that your GPS reference frequency may vary by up to about 
+/- 5E-11 during the day.

And, your OCXO is sensitive to temperature, power supply and air 
pressure changes.

Regards,
Adrian


Am 04.09.2020 um 08:50 schrieb Matthias Welwarsky:
> Hi,
> 
> I mentioned in a previous email that I seem to have picked a particularly bad
> (broken?) OCXO for GPSDO testing. It drifts at a very high rate, from the DAC
> graph I calculate it is around -4e-4 Hz/hour. It's been on for about 1 week
> now and the drift doesn't seem to come down, or maybe just marginally.
> 
> Of course, this being a surplus OCXO with unknown history, odd startup
> behavior is somewhat expected but so far I haven't seen anything this drastic.
> 
> Could this be OCXO retrace? How long can that phase last? I'm trying to decide
> if I should give it another week or just scrap it and move on.
> 
> Regards,
> Matthias
> 
> 
> 
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