[time-nuts] Thunderbolt stability and ambient temperature

Tom Van Baak tvb at LeapSecond.com
Tue Jun 9 18:43:38 EDT 2009


> Adding mass increases the thermal capacitance adding insulation
> increases the thermal resistance.
> It is possible to construct an enclosure with a long thermal time
> constant together with relatively low thermal resistance so that the
> temperature of a GPSDO or similar device within the enclosure only
> increases by a relatively small amount.
> 
> Multiple alternating layers of thermal conductor and thermal insulator
> reduce thermal gradients as well as temperature fluctuations.
> 
> Having an outer conductive layer reduces the temperature gradients over
> the insulator surface.
> 
> Readily available inexpensive aluminium foil is a cheaper alternative to
> expensive noble metal foils.
> 
> Silica aerogel is one of the most effective insulators.
> 
> Balsa wood has been used as the insulator in portable temperature
> controlled ensclosures for standard cells.
> 
> Bruce

And the amazing thing is that this temperature control double
oven technology for oscillators was well advanced in 1931. See:

http://www.leapsecond.com/museum/gr676b-50kc/

and especially the "temperature control apparatus" patent:

http://www.leapsecond.com/museum/gr676b-50kc/US1967185.pdf

/tvb





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