[time-nuts] quartz / liquid nitrogen

[Bob kb8tq]

Hi

If you dig back in the FCS archives, you will find papers on “cold” OCXO’s. You also 
will find papers on cryo cooled quartz. The bottom line appears to be that if you are
going to all the trouble of cooling things, sapphire (or other exotic materials) are a 
better bet. 

Quick simple answer: not enough improvement in ADEV, aging, or phase noise to 
make it wroth it. As PHK mentioned, coming up with a “ideal” cut for your arbitrary
temperature  cryo setup is non-trivially difficult ( = plan on spending a few million 
dollars and a lot of years).

Bob

> On Apr 2, 2018, at 3:46 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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