[time-nuts] Improving the stability of crystal oscillators

[Brooke Clarke]

Hi Bruce:

Details on your experiment please.
Hole/pipe diameter, material?
Depth?
Delta T at different depths vs surface ambient?
Soil type?


Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com
http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam


Bruce Griffiths wrote:
> ); SAEximRunCond expanded to false
> Errors-To: time-nuts-bounces+brooke=pacific.net at febo.com RETRY
> 
> Brooke Clarke wrote:
> 
>>Hi Bruce:
>>
>>I've also looked into drilling a hole (garden hose, 90 deg fitting & pipe with 
>>end smashed flat to make a nozzle will easily drill as deep as the pipe is 
>>long).  Then using a short length of capped copper pipe at the bottom and the 
>>rest PVC.
>>
>>Like I think here in California wine country 4 feet would be plenty deep.  But 
>>this method only works at your home location.  Not too good for a clock that 
>>will be sent to someone else.
>>
>>I think the long time constant method can be done in a few cubic inches.
>>
>>Have Fun,
>>
>>Brooke Clarke
>>  
> 
> Brooke
> 
> The required depth depends on the soil diffusivity and the temperature
> stability required.
> It is instructive to install thermometers at depth intervals of a foot
> or so and record the temperature fluctuations experienced by each
> thermometer.
> This was first done around 1860 by Forbes.
> I repeated the experiment in 1966.
> 
> Bruce
> 
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