[time-nuts] Morion MV89A position

Poul-Henning Kamp phk at phk.freebsd.dk
Wed Jan 29 09:06:21 EST 2014


In message <20140129172157.LveisisT at smtp18.mail.yandex.net>, Charles Steinmetz 
writes:

>>The best result I have managed so far, was by wrapping the OCXO in
>>domesticated geology, (bricks, concrete, cinderblocks etc), which
>>has high-ish thermal capacity but only moderate thermal conductance.
>
>Agreed.  The cast aluminum box I mentioned in my previous post is a 
>good way to add thermal capacitance without adding much thermal 
>resistance.

That's exactly what you do not want.

Your aluminium box will very efficiently transport temperature
changes from its full surface to your OCXO.

Silver, Copper and Aluminium have high thermal conductivity and
should only be used as conduits to reservoirs of stable temperatures,
not as enclosures in unstable temperatures.

What you want when the enviroment is not controllable, is high
thermal mass and *moderate* thermal conductivity.

A plastic box with lid and filled with dry sand will do much better
than your alubox.

Cat-litter doesn't work, it has too low mass and thermal conductivity,
but sand can be bought ovendried and cleaned for various hobby and
construction purposes.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.


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