namichie at gmail.com
Sat Jun 10 00:22:32 EDT 2017
It is possible that the ageing of a crystal is associated with the redistribution of the surface water
monolayer, under the influence of the minute temperature gradient of an oscillating crystal.
Some energy is dissipated in the quartz, so some gradient may exist.
When a crystal is resting, the water may redistribute in the sealed package, but when run again, the water
redistributes due to the temperature differences.
Adsorbed water is in equilibrium with its environment, and, given time, will migrate along temperature gradients.
It could be just one more mechanism in frequency drift.
I would try using a reactive metal getter in the package to pick up any mobile water molecules.
> On 10 Jun 2017, at 9:52 AM, Bob kb8tq <kb8tq at n1k.org> wrote:
> You can’t quite process a crystal at 300C, but you can get close.
>> On Jun 9, 2017, at 7:38 PM, Neville Michie <namichie at gmail.com> wrote:
>> My memory of high vacuum work is that you need to pump for 4 hours
>> at 300C to remove the water monolayer from glass.
>> On top of the that water monolayer is another water monolayer that comes off more easily,
>> and on top of that another………..
>> Neville Michie
>>> On 9 Jun 2017, at 10:57 AM, Richard (Rick) Karlquist <richard at karlquist.com> wrote:
>>> On 6/8/2017 5:08 PM, Bob kb8tq wrote:
>>>> In this case hydrogen + oxygen (like from oxidized metal) goes to H20. You very much do
>>>> not want water running around inside your crystal holder… Helium is inert.
>>> Exactly right Bob. The 10811 guys used to go nuts
>>> about keeping water out of their vacuum system.
>>> There were certain temperatures known as "water
>>> points" at which some water was released.
>>> The retained water was in spite of the temperature
>>> already being above 100 degrees C (boiling).
>>> It has something to do with monolayers of
>>> water molecules not boiling away.
>>> Rick N6RK
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