[time-nuts] Raw phase data of super-5065
kb8tq at n1k.org
Fri Jun 15 11:37:44 EDT 2018
I would not find it at all surprising that any of the older Rb’s are running below
1x10^-11 / month these days ( after a good run-in). Below 1x10^-12 is pretty amazing.
The FRK’s will normally hang out a bit above that point. Indeed, getting all of the pressure
and temperature stuff stable enough to see the aging is a bit of a challenge. The only
hope for most of us is “it’ll all average out …”.
> On Jun 15, 2018, at 11:25 AM, Ralph Devoe <rgdevoe at gmail.com> wrote:
> This is not a Super-5065, but it might be interesting. Its a 12 day
> measurement of a stock 5065a against a 5071a cesium standard. There are 10K
> points at 100 second intervals. It passes through 10(-13) at about the 6000
> second mark and settles in at 5-7 x10(-14) at longer times.
> I think this is a lucky measurement, in that during this period our
> weather was very stable (as it often is in Northern California during the
> summer). The barometric pressure at the local airport only varied by +/- 4
> mbar during the twelve days. If you use Corby's value of 1.4 x 10(-14) per
> mbar from May, 2016 then this seems reasonable. The temperature is also
> very stable in Leo Holberg's very quiet lab at Stanford. We're setting up
> to log pressure and temperature.
> The other unusual thing about this 5065a is that its aging rate is
> very low, way below 10(-12) per month. I've been tracking it since Jan
> 2018 and I can't yet get a good number. Its an old unit, made in 1975, and
> appears to have been turned off for many years. The diode board is just
> slightly singed, not brown at all. Its been turned on continuously for the
> last two years.
> This was measured with a sine-wave fitter, but any method should
> give the same results, given the long times. I've also been comparing my
> other "newer" 5065a against the 5071a and it shows the usual warmup drift
> and has a standard aging rate.
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