[time-nuts] Re: Is SC the most stable cut for lowest phase noise?

[Lux, Jim]

On 6/10/22 12:13 PM, Richard (Rick) Karlquist wrote:
> I think there is a severe misunderstanding of this issue.
> First of all, "rapid warmup" is a red herring.  The real
> issue is "rapid frequency stabilization".

Indeed. But to a certain extent, that's why oscillators don't have 5 
second warm up times - it wouldn't help. So the "few minutes" is a good 
compromise between design simplicity and waiting for the internals to 
equilibrate.

I suspect that those fancy USOs in vacuum bottles take a long, long time 
to come to equilibrium.

And that is one of the claims to fame of the CSAC - from power on to "on 
frequency" is quite short.


>
> The time it takes for the oven to cut back (typically only
> a minute or two) is a very minor part of the time budget
> to get to frequency stabilization.  You could have an AT
> cut oscillator that reached "oven warmup" in 1 second, but
> then you would have something like a 1 hour wait to get
> frequency stability, due to the thermal stresses.