[time-nuts] AN/URQ-13 question How long

[paul swed]

Well the old URQ-13 falls is about 54 years old. But how its been handled
over that time will never be known. Poorly is the best guess. No
expectation that it will be a super oscillator like the old Sulzers. I am
really trying to understand if its been recovered to a respectable state
as it may have been intended to be in 1967. It will never be my main
reference.
The best guidance I have is the URQ-10 that is well published.
Over the last 24 hours its really settling down. I am now fine tuning with
the digital readout control 1 part E-11 per digit.
Appreciate your thoughts.
Regards
Paul

On Thu, Mar 4, 2021 at 9:51 AM Magnus Danielson <magnus at rubidium.se> wrote:

> Hi,
>
> On 2021-03-04 11:15, Hal Murray wrote:
> > paulswedb at gmail.com said:
> >> But since the units been off for at least 15 years and heavens knows
> how long
> >> before that. Any thoughts on how long it might take to stabilize days
> weeks
> >> months. Its pretty stable as is just wondering.
> > It's an exponential tail.  How stable do you call stable?
> >
> > What do you have to measure it with?  How stable is your environment?
> >
> These tails have been measured for years. As long as it is slower than
> the application can handle, it becomes only the issue of being "within
> range". This is the "aging" period. Environmental may cause more severe
> deviation eventually, but a power-down/power-up even cause retracing and
> that will restart the process.
>
> So, it ends up being about being acceptably stable, as in not being
> annoyingly large anymore.
>
> There is fairly good evidence that crystal oscillators do not have much
> of wear mechanisms if done with a bit of care. There is oscillators out
> there that has been running 40-50 years in continuous operation. Getting
> any atomic clock live that long is more of a challenge, they need to be
> serviced because of explicit wear mechanisms. I think the PTB CS2 and
> CS3 clocks is the longest operations beam clocks, but they also have
> work done on them, and upgrades. We end up discussing some of that in
> the IEEE P1193 group on environmental effects on frequency sources.
>
> Cheers,
> Magnus
>
>
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