[time-nuts] Some More questions

Rob Kimberley time.bandit at btinternet.com
Thu Jan 19 09:24:53 EST 2006


I visited an MoD microwave lab many years ago, and they used to run all
their temperature sensitive stuff on a huge steel table about 3 inches
thick, apparently to minimise the effects of ambient temperature change.

Rob K 

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Poul-Henning Kamp
Sent: 19 January 2006 14:08
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Some More questions

In message <43CF928D.4030101 at erols.com>, Chuck Harris writes:

>It would be interesting to see how such an oven performs compared to 
>the traditional double oven.

According to a guy at the danish metrology lab, the optimal strategy is
moving as little heat as you can get away with.

They keep most of their stuff in a basement room where the air condition is
set "hysterically" to 21 C.

Temperature sensitive things then get a layer of insulation, for instance
their resistance standards are mounted inside a huge aluminium block
(roughly 50x50x25 cm) which acts as a buffer for any fluctuations the
aircondition / open doors etc may cause.

Their suggestion for a cheap environmental chamber is an old fridge where
you keep the door closed.  After some weeks it will have reached a stable
temperature relative to the room.

If your room temperature is not stable, run temperature controlled water
through the loop of the fridge.

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
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Never attribute to malice what can adequately be explained by incompetence.

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