[time-nuts] quartz / liquid nitrogen

Tisha Hayes tisha.hayes at gmail.com
Mon Apr 2 16:47:02 EDT 2018


You also run in to mechanical vibration issues from the cooling system. At
the temperatures involved you are looking at something like a Stirling
cycle cooler.

Here is a good article;

https://arxiv.org/pdf/1309.5445.pdf

Maintaining a very stable temperature probably has a much greater impact.

Tisha Hayes, AA4HA

*Ms. Tisha Hayes*


On Mon, Apr 2, 2018 at 2:58 PM, Poul-Henning Kamp <phk at phk.freebsd.dk>
wrote:

> --------
> In message <299B45118C9248498D7B4F3AFE72231E at pc52>, "Tom Van Baak" writes:
>
> >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.
>
> Whispering gallery sapphire resonators at cryogenic temperatures
> is a thing for phase-noise, but those are dielectric (microwave)
> resonators, not piezoelectric resonators.
>
> > Would that dramatically lower temperature improve phase noise &
> > short-term performance?
>
> Yes it will reduce your thermal noise as a source of PN, and
> dramatically so.
>
> But I doubt short and long term performance will improve.
>
> Even if you can find a zero-turnover cut at a convenient temperature,
> I don't think anybody know how to produce mK temperature *stability*
> at cryogenic temperatures ?
>
> --
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
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