[time-nuts] Aging rate of crystals

Richard (Rick) Karlquist richard at karlquist.com
Mon Feb 18 01:26:48 EST 2008

At the beginning of the E1938A project, I did a bunch of
characterization of 10811 oscillators.  At the Santa Clara
Division, we had first class environmental test chambers
with heating, cooling, humidification, de-humidification,
and nitrogen purge.  The nitrogen was also available for
fast cooling.  The 10811 response to humidity was very rapid,
like 10 or 15 minutes, almost as fast as the chamber
itself could ramp.  This occurred whether going from
dry to humid or the other way around.  I don't remember
seeing any slow "tails" on the response.  The immediate
humidity response was on the order of a month of aging,
so any humidity related aging effects would be masked.

Rick Karlquist N6RK

Thomas A. Frank wrote:
>> The best experiment I can think of to prove this is to run the
>> oscillator in a paper bag until it is stable,
>> then trickle a flow of dry nitrogen  into the bag for a day or two
>> and watch for oscillator drift as the humidity
>> in the oven drops to extremely low values.
>> It is a pity that I do not have bottled gas on tap any more.
>> cheers, Neville Michie
> I like your theory, it has a marvelous macroscopic physical component  
> to it.
> A way to run that test without any bottled gas would be start during  
> a very humid spell (the stabilize things at a humid level; say 80%  
> RH), then to put the crystal assembly into a sealable plastic  
> container (Tupperware for US folks) with a bunch of silica gel or  
> other desiccant.
> The humidity in the container will drop to well below 20%, and stay  
> there until you open the container.  That's a pretty decent range to  
> work over.
> Tom Frank, KA2CDK
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