[time-nuts] HP 10811 Response I Replies
cfharris at erols.com
Thu Sep 22 23:17:06 UTC 2011
You had a leak. If epoxy was really as bad as you indicate,
it would not be usable for holding pressure, or mild vacuum,
and yet it is. Somehow, someway you left a big hole in the
Rick Karlquist wrote:
> Perry Sandeen wrote:
>> Wrote: Doing what you describe will result in a very sensitive humidity
>> sensor, having eliminated the thermometer effect.
>> I do not understand. I believed that since the OCXO temperature will be
>> substationally higher than the surrounding temps, any residual moisture
>> would migrate to a lower temperature. The fiberglass insulation inside
> Heating up a space does not change the absolute humidity AFAIK.
> It only changes the relative humidity. We did tests where we
> "sealed" a 10811 inside a box that was held together with so-called
> "hermetic" epoxy. We put it in an environmental chamber at a
> constant temperature and constant low humidity and let it stabilize.
> We then increased the humidity to something like 80%,
> while holding the temperature constant. Within
> minutes the frequency changed more than the spec for the entire
> temperature range. Therefore, you should do your experiment with
> the hermetic version of the 10811. The hermetic version is soldered
> shut, rather than using epoxy, which turns out not to be hermetic,
> no matter what they claim.
> Rick Karlquist
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