Hi 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 …”.
Bob > On Jun 15, 2018, at 11:25 AM, Ralph Devoe <rgde...@gmail.com> wrote: > > Hi, > 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. > > Ralph > <060118_01.jpg>_______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > https://lists.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to https://lists.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.