Thanks- What I'm interested in achieving is the lowest posible energy
requirement for a set of quartz frequency stds. It seems to me that using
the close to iso-thermal 'hole in the ground' arrangement is a useful step
in that direction as it should minimise the power necessary for
environmental control.
When we had the bad quakes here back in 2010/2011 I lost all power to the
gear for several days and the backup batteries only held it running for
about 36 hours. This, after the oscillators had been running continuously
for 7 years. So, rather than invest heavily in a higher capacity battery
bank, I'm looking to get the lowest energy requirement for the essential
things like reference oscillators and a minor amount of logging eqpt.
Inconvenience re access etc is a minor issue in the overall scheme of things
from my point of view.
I guess I may have to just try it.
Regards
Dave Brown
Christchurch, NZ
----- Original Message -----
From: "Charles Steinmetz" <[email protected]>
To: "Discussion of precise time and frequency measurement"
<[email protected]>
Sent: Thursday, January 30, 2014 2:44 PM
Subject: Re: [time-nuts] Morion MV89A position
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
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