[time-nuts] 10811 Extra Lagging etc
brooke at pacific.net
Tue Jun 20 23:50:26 EDT 2006
Thanks for pointing that out. Maybe the factor is air density. I know
air density was the thing we used to monitor to jet the carbs in racing
It was better than using a barometer and/or thermometer.
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
Rick Karlquist wrote:
>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:
>>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.
>>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
More information about the time-nuts