[time-nuts] Thermal impact on OCXO

[Mark Sims]

Several years ago I replaced the OCXOs in some Tektronix DC5010 counters with surplus Oscilloquartz 8663 DOCXOs.   The darn things have freaky good aging characteristics.   They have been on 24/7 (except for a few brief power-outages) for over 3 years.   After a month I set their freq against a cesium oscillator.   They still show 10 MHz out to 8 or 9 decimal places.

I just got in an Oscilloquartz Star-4 ATDC (automatic temperature / drift compensation) that uses the same DOCXO.   They take 24 hours from a cold start before the ATDC learning kicks in (you can fake it out by power cycling during that interval and it thinks it was a brief outage and reports a 1 hour learning delay).   After an unspecified time (at least several days) the device learns the compensation characteristics and the holdover performance status switches from POOR to IN-SPEC.   I have not yet gotten it past the learning stage...

Oh,  and Lady Heather now speaks Star-4 management interface commands which are also used on a NEC GPSDO that shows up on Ebay... I have one of those on order.

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> OSA8663: per year, 3.0E-8, in 10 years < 30.0E-8