[time-nuts] Cheap Rubidium (heatpipe cooling for)

[Bob Camp]

Hi

My main concern with gradients would be second order effects on the servo circuit. As you change the zero of the phase detector you get a net short term frequency shift. Gradients on the pc board -> stress on smt parts -> value changes -> phase shift.

Bob

On Dec 24, 2009, at 8:09 PM, Magnus Danielson wrote:

> Bob Camp wrote:
>> Hi
>> I certainly agree that, say potting the circuit board, would be a lot easier than some of the stuff we have been talking about. 
> 
> I am not sure that it would significantly improve the case.
> 
> The physical package as a whole, needs temperature stabilization. Double-oven strategies etc. is among them. At the same time it is a heat source, so we need to cool a few wats off it. Except for possibly the resonant cavity, I don't think thermal gradients is as important as stable temperature, where as the crystal(s) of the electronics boards is another story. The electronics might enjoy a cooler and somewhat gradient free environment, but for longer taus most of the effects would be servoed in to the rubidium resonance anyway, so I suspect most of those long-term effects can be focused on the physical package.
> 
>> My main concern about tearing up the unit is impacting the magnetic shielding. I assume that the outer enclosure forms part of the magnetic shield (at least that's what the data sheets say ...).
> 
> Good point.
> 
> Cheers,
> Magnus
> 
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