[time-nuts] Continously drifting HP 10811...
kb8tq at n1k.org
Wed Nov 8 12:46:00 EST 2017
One of the weak points of a normal 10811 is that it is not hermetically sealed. Left
in storage for years, they “soak up” humidity. In some cases it can take a fairly long
time (weeks, months) for them to fully dry out. Until they have been run for at least a
week, don’t get excited about the drift.
> On Nov 8, 2017, at 12:24 PM, Ulf Kylenfall via time-nuts <time-nuts at febo.com> wrote:
> I am about to try to repair a second 5065Aand have now tested a number of 10811 Quartzoscillators that was in the junk box.
> In order to test the 10811, I put them it in a chassisthat is used for GPS-locking. Adjust for lockand then monitor the EFC-voltage over time.
> Starting out with a lock condition and the EFCvoltage adjusted to -2.500V I can see that theoscillators exhibit a monotonus EFC voltagedrift towards 0 volts. About + 1 mV in 3 minutes.
> By comparison, I have a 10811-60109that was tested in the same GPS-application andthis unit is rock-steadyand that does not show any sign of EFC drift.
> Test time has been 3 Days, and I beleive thata 10811 should have been able to reachthermal equilibrium during this time.
> I can and will (of course) take them apart.Anything special to look for other thanthe usual signs of long-term over-heated discretes?
> Ulf Kylenfall - SM6GXV
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