In the 70's I did a 4 inch pipe 20 feet in the ground in Dallas.
Temperature was better than 0.1 C. Got canvas coin bags from my local bank filled
them with sand and lowered them one at a time with line each one a subsequent
number. Used it for 18 years.
Bert Kehren
In a message dated 1/29/2014 8:46:29 P.M. Eastern Standard Time,
csteinmetz@yandex.com writes:
Dave wrote:
what about replacing your aluminium box with a, say 2 foot piece
of 6 inch pvc pipe (ocxo suspended inside it clear of the wall and
sealed off ends) and burying that a few feet in the ground?
I share Poul-Henning's lack of enthusiasm for burying
electronics. But if you try it, I'd be interested in hearing how it
works. Depending on your climate, you may need to go deeper than a
few feet to achieve a reasonable approximation to isothermy. Of
course, even a few feet should get you to where the rate of change of
temperature is quite slow and the peak-to-peak swing is lower than
the outside air temperature. (But is that the standard? Aren't most
time-nuts labs in climate-controlled living spaces?).
If you really want to go nuts, it's pretty simple to put the cast
aluminum box into a larger enclosure with a small, thermostatically
controlled fan. If you bond a temperature sensor to the inside wall
of the cast box, it's easy to hold the temperature of the cast box to
well within 0.1C.
Best regards,
Charles
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
In the 70's I did a 4 inch pipe 20 feet in the ground in Dallas.
Temperature was better than 0.1 C. Got canvas coin bags from my local bank filled
them with sand and lowered them one at a time with line each one a subsequent
number. Used it for 18 years.
Bert Kehren
In a message dated 1/29/2014 8:46:29 P.M. Eastern Standard Time,
csteinmetz@yandex.com writes:
Dave wrote:
>what about replacing your aluminium box with a, say 2 foot piece
>of 6 inch pvc pipe (ocxo suspended inside it clear of the wall and
>sealed off ends) and burying that a few feet in the ground?
I share Poul-Henning's lack of enthusiasm for burying
electronics. But if you try it, I'd be interested in hearing how it
works. Depending on your climate, you may need to go deeper than a
few feet to achieve a reasonable approximation to isothermy. Of
course, even a few feet should get you to where the rate of change of
temperature is quite slow and the peak-to-peak swing is lower than
the outside air temperature. (But is that the standard? Aren't most
time-nuts labs in climate-controlled living spaces?).
If you really want to go nuts, it's pretty simple to put the cast
aluminum box into a larger enclosure with a small, thermostatically
controlled fan. If you bond a temperature sensor to the inside wall
of the cast box, it's easy to hold the temperature of the cast box to
well within 0.1C.
Best regards,
Charles
_______________________________________________
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
