[time-nuts] Morion MV89A position

[Don Latham]

>
> My question is, how does one design an enclosure to prevent this
> mistake? Or is it trial and error. Perhaps put a thermistor on the OCXO
> and if the case temperature rises beyond what is normal case temperature
> in free air, then the enclosure has too much insulation?

I suggest a thorough reading of Schaum's summary book on heat transfer,
or get a secondhand copy of Incropera & DeWitt (?sp). It's pretty simple
to build models for the planned enclosures. For example, the enclosures
with insulation are mostly conduction transfer problems, the clever
enclosure mentioned a couple of days back, with nylon standoffs and a
sealed dewar (?) is a combined convection/radiation balance problem,
harder because of the convection cells that will set up inside the
dewar. Forget about thermal resistance, thermal capacitance, etc, and
look at the basics of heat transfer!
Also think about this: What's the REAL problem?
Enough rant.

>
> With all this talk about thermal capacitance and resistance, perhaps
> what we need is a thermal diode; it lets heat out but prevents thermal
> fluctuations from getting in. A thermal Gore-Tex layer.

There's always Maxwell's demons, if you can catch one :-)


-- 
"The power of accurate observation is commonly called cynicism by those
who have not got it."
 -George Bernard Shaw


Dr. Don Latham AJ7LL
Six Mile Systems LLC
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