While in the navy, I had to repair a hp cesium standard.
The control circuit had the oscillator slewed to one limit, I do not
remember whether high or low.
We had no spare parts to support this standard.
The only option was to run the standard open loop.
Over a period of two hours, I had the standard off for no more than 15
minutes total.
To get the standard back on frequency, I had to compare this standard to
the other standard using an oscilloscope to produce a Lissajous pattern.
I set the oscillator on frequency by stopping the rotation.
I checked it again in 6 hours and the pattern was fastly rotating.
I reset the frequency and checked it at 6 hour intervals.
It took two weeks for the oscillator to thermally stabilize after being
off only 15 minutes.
Be prepared to have to wait to get the oscillator thermally stabilized.
I am not positive that this was a 10544A, but, it was a similar ovenized
precision oscillator.
YMMV
73
Glenn
WB4UIV
On 2/28/2016 8:10 PM, Bob Camp wrote:
Hi
Except ….
The big steps give you more “thermal shock” on a BT and that slows things down.
Bob
On Feb 28, 2016, at 7:28 PM, Richard (Rick) Karlquist <rich...@karlquist.com>
wrote:
On 2/28/2016 7:01 AM, Bob Camp wrote:
Hi
It’s not an electrical issue as much as a heat issue ….
Before you start, consider that you will be doing something like:
Move trimmer 1 turn CW
Wait 10 minutes
read frequency
Move trimmer 1 turn CW
wait / read
Move trimer 1/2 turn CCW
wait / read
Move trimmer 1/4 turn CW
wait / read
Move trimmer 1/8 turn CCW
wait / read
Move trimmer 1/16 turn CW
wait / read
Move trimmer 1/32 turn CW
wait / read
That is indeed an ideal version. You likely will do multiple steps at each of
the stages rather
than get it right the first time. The part needs to be warmed up for a few days
before you
can get to the 1/32 turn level. You also need a good standard to compare to.
Bob
Instead of that, start with the pot at max temp, and have the counter make
measurements at, say, 1 second intervals as the oven warms up.
You can tell by looking at the plot what the peak frequency is. Now
that you know the peak frequency you are shooting for, it will take
a lot less trial and error to find the oven setting that produces it.
Rick
_______________________________________________
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
_______________________________________________
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4...@arrl.net AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"
---------------------------------------------------------------------------
_______________________________________________
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
