[time-nuts] quartz / liquid nitrogen

[Dana Whitlow]

Is the thermal noise generated in the loss in a quartz resonator a
significant part
of the overall phase noise picture?  I would have not thought so.  I'd
think that a
greater benefit ought to be derived from chilling the other parts in the
oscillator,
such as the active devices.  Unless, of course, chilling the quartz
actually improves
the Q significantly, which I don't know about.

If cooling (whatever) by just a modest amount helps much, then one could
consider using Peltier cooling.  It doesn't really get things very cold,
but is a
lot more convenient than either dry ice or LN2.  But then you don't get the
fun
that you do when playing with LN2, either.

Dana


On Mon, Apr 2, 2018 at 2:46 PM, Tom Van Baak <tvb at leapsecond.com> wrote:

> Has anyone tried running a quartz oscillator at liquid nitrogen
> temperatures: -196 C (-321F, 77K)? It's probably impractical commercially,
> but maybe something of value to a time nut. Would that dramatically lower
> temperature improve phase noise & short-term performance? Is there a
> crystal cut that could be optimized for 77 K instead of ~25 C (room) or 60
> C (oven)?
>
> If not Nitrogen, how about dry ice (-109F -78C)?
>
> /tvb
>
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