Walter Shawlee 2
2018-11-02 18:51:42 UTC
in my various HP counters, and generally they work very well, with
usual errors under 0.01Hz and very minor drift over time.
a few months ago, I had a power interruption, and black out for a few
along with the usual erratic restart from the power company. shortly
afterwards, I built a nice little
homemade TM500 plug-in OCXO unit to fit on my bench, and without giving
it much thought, used
my bench standard (an hp 435B-K26 power/frequency reference with an
internal 10544A) to cal it. all seemed good.
soon after, I was working on an hp 5334A counter, and added a 10811A as
as upgrade from my
spares and suddenly, I had a big 1.3Hz error at 10Mhz when I cross
checked it to my bench references AND a rubidium. I brought over my
recently cal'd rubidium from the upstairs lab, and yes, there was now
clearly a big step error. my upstairs 5335A with a 10811A had the same
these 2 units are always on for stability, so both got cycled the same
way during the power failure.
it seems that the power failure cycle had bumped the internal 10544A
oscillator inside the 435 by that amount, as well as the 10811A inside
the 5335A. I have never seen that effect before, both the ovenized
osicllators from hp have been very reliable for me, so I thought I would
put that info out in case anyone else has seen this effect and knows the
using the rubidium (which I keep off until I need it, and wait for at
least 2 hours for best settling), I reset everything back to a flat
10Mhz, and all was well, except that the first 10811A I put in the 5334A
conked out (oven still fine, but the oscillator went dead, giving the
dreaded "no osc" message on the counter). another spare fixed that, and
two days of drift testing to get everything back where it belongs.
anybody want the bad 10811A?
anyway, just thought the information might be handy for others. the EFC
range on the 10811A/10544A is *only 1Hz*, so such a big jump is unusual
to say the least. it required the main coarse adjustment to fix.
The 435B-K26 is a pretty remarkable widget if you ever see one, it makes
a great 10Mhz reference and 1mW power reference in one little box, very
useful for an RF bench. One of hp's rare and forgotten treasures.
all the best,
Walter Shawlee 2
Sphere Research Corp. 3394 Sunnyside Rd.
West Kelowna, BC, V1Z 2V4 CANADA
Phone: +1 (250-769-1834 -:- http://www.sphere.bc.ca
We're all in one boat, no matter how it looks to you. (WS2)
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But, that doesn't mean other things don't come in handy. (WS2)
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