Within minutes the frequency changed more than the spec
For humidity to get thru something like that it takes weeks or more it does
it at all.
That fast of reaction, Sure sounds like some other effect like blowing a
little air on the case or loading the osc output with water in the output
cable etc, etc.
I think it is safe to say the effect was not due to water inside, unless
there was a hole.
ws
*****************
Chuck Harris cfharris at erols.com
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
bucket.
-Chuck Harris
************
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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