[time-nuts] 10811 Extra Lagging etc
richard at karlquist.com
Tue Jun 20 20:54:46 EDT 2006
You must be kidding. No way are Zip Lok bags hermetic.
Water vapor will diffuse right through. (Note that waterproof
does not equal hermetic).
Brooke Clarke wrote:
> HI Rick:
> For humidity control in other applications I have used Zip-Lok bags.
> How about putting the 10811 in a Zip-Lok bag and run the wires through a
> hole that gets epoxy sealed? Some desiccant would lower the humidity if
> that is an advantage.
> Have Fun,
> Brooke Clarke
> w/Java http://www.PRC68.com
> w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
> Richard (Rick) Karlquist wrote:
>>>Given that HP's engineers have done such a good job with
>>>the oven and oscillator design, is there anything to be gained
>>>by adding extra thermal insulation (lagging)? How much
>>Not a good idea. The best thing you could do to improve
>>temp stability of a 10811 is to tweak the resistors that
>>proportion the power between the two heater transistors.
>>At some ratio, the thermal gain will peak at over 1000
>>typically. If you just take pot luck, you would be lucky
>>to do 100. You are still limited by the tempco of the
>>electronics, no matter what thermal gain you achieve at
>>You should also be aware that the 10811 is fairly humidity
>>sensitive, which can seem like temperature sensitivity
>>if the humidity and temperature change together.
>>The HP E1938 was a much better design in terms of environmental
>>insensitivity, but that didn't help much because the
>>ultimate stability was limited by crystal frequency jumps,
>>which didn't seem so bad with the 10811 due to the large
>>environment errors in it. In the E1938 they stuck out like
>>a sore thumb.
>>Rick Karlquist N6RK
>>time-nuts mailing list
>>time-nuts at febo.com
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