Related to that ..

If you use the ovened oscillator for temporary use away from the home
GPSDO, how good will the oscillator be with those interruptions to power /
temperature, and will it stabilise during the period you're using it there ?

I don't know what the vales are, but I'd suggest the option 010 will never
reach the 001's spec and the 001 may not even be justified.

On Tue, Jun 28, 2022 at 6:13 PM Dr. David Kirkby via time-nuts <
time-nuts@lists.febo.com> wrote:

David
Great comment on power. I used to run everything 24 X 7 also including
various radio sets. That was all fine when Mr. Ready Killowatt (Believe he
worked at a Nuclear Power plant) was 2-3 cents a KW and the only other
charge was a meter rental.
But then the darn rates started going up. Now I have a GPDSO with TCXO with
distribution. Power switches on everything. I can switch better GPDSOs into
the distribution chain if needed. Same with CS and Rb references. But 99%
of the time the TCXO is good enough even from a cold start. That system
when on as I recall is maybe 4 watts. Its not a lot.

I think you nailed it on what may be available in the wild. Hard to say how
good or bad something is. Some sellers will let you check within 30 days.
The question is how good does it have to be to take to a club meeting?
Regards
Paul
WB8TSL

On Tue, Jun 28, 2022 at 1:13 PM Dr. David Kirkby via time-nuts <
time-nuts@lists.febo.com> wrote:

Hi

The “typical” 10811 struggles when shut down for a while. Once the oven
is turned off, the boards are just sitting there in whatever environment your
lab provides. Do they soak up humidity or is it something else? We could
(and have) debated that quite a bit.

Regardless of what the issue is, the bottom line is that when you turn the beast
back on again, it might take quite a while for it to become reasonably good.
In some cases that means a couple weeks to hit spec limits. In others it might
mean a week or two to get back to “as good as it was”.

A good 10811 will do much better than what the specs would suggest. It may
be a “one in a hundred” sort of item, but they do exist. Ones that barely / don’t
meet spec (even after a month on power) also exist and they are a lot more common
than the ones we brag about with various plots.

What’s the point? Keeping the unit on power is a good idea, even if you have
a good example. Keeping a poor one on power still will not turn it into a good
one. Checking out the units you have is a “needed thing” before you start counting
on them for this or that. They all left the factory a long while ago.

It does matter just what you are counting on the OCXO to do. Does phase
noise at 100 KHz offset matter in your case? Does 10 second ADEV at 5x10^-12
degrade your performance compared to 5x10^-13? Is drift the only thing that really
matters? ( and when did you last set it on? :) :) ) If so, temperature stability (in a
“transport someplace” situation)  likely also matters, testing it is not something
most are set up to properly do ….

One alternative: Grab a fairly typical telecom Rb. Put a (cheap) cleanup oscillator
on it. Use that as your “portable” reference. Run it on batteries (or a 12V plug in
the car)  as you transport this or that item here or there. Let it sit unpowered on
the shelf until about a week ahead of your planned expedition.

Fun !!!

Bob

On Tue, 28 Jun 2022 at 20:04, Bob kb8tq via time-nuts <
time-nuts@lists.febo.com> wrote:

Part of my problem is that if I ever wanted to sell this, I'd like to sell
it with an oven that was designed to meet the specifications given in the
frequency counter manual for option 010, which are better than the 10811A.

Another quite practical issue is setting the blinking frequency, as the pot
on the oscillator seems too touchy. I set a signal generator to 20 GHz,
which was fed from a GPS frequency reference. The output of the signal
generator was then fed into the counter. Getting the counter to read within
100 Hz is extremely difficult, as the tuning control is too coarse. As I
write the frequency counter is reading 83 Hz higher than 20 GHz.

To be honest, that's "good enough" for what I am practically going to
need. But I would like to do better if possible.

Dave

Hi

All HP 10811’s came off the same line and with the exception of the “weird” one used
in the original HP GPSDO, they all had the same parts / same optimizations in them. The
only thing that was done to make this or that dash number was to screen the finished
units. Once “enough” of this or that spec came out of screening, they stopped looking.
The “next one in line” might have well beat any of the ones in the batch … they simply
had no time ( = funds ) to screen everything.

Since this screening was done a long time ago, there is no way to know if the OCXO
you have still is a “good one”. Stuff happens over time …. subtle changes rarely get
noticed.

Bob