[time-nuts] HP 5345A

John Miles jmiles at pop.net
Fri Dec 29 16:43:47 EST 2006

I don't recall; this oscillator was installed in a piece of gear I sold
several years ago.  I checked it every few months while I had it.  All I
remember is that the note I used to keep track of its calibration had at
least four entries on it at the time I sold the generator, and I'm very sure
it never left +/- 1E-9, always measured after the 8662A had been left
running for at least a couple of hours.  Whether it looked like a random
walk or not, I couldn't say.

Lucky environmental factors must have played a big part because -- as Rick
says -- they aren't normally that stable.  There is a definite
bathtub-shaped curve at work, as well.  If the units that Rick saw at
Agilent were all brand-new, then of course they weren't very stable compared
to the OCXO in this 8662A.  I could tell that it had been running for a long
time when I received it, because I observed almost no accelerated aging
during the first few weeks of service.

Likewise, from what I have seen, the early-80s OCXOs don't tend to stay put
as well as the newer ones do.  Whether that's due to materials/manufacturing
quality or simple aging is impossible to say, given the limited number that
I have experimented with.

-- john, KE5FX

> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of Hal Murray
> Sent: Friday, December 29, 2006 1:29 PM
> To: richard at karlquist.com; Discussion of precise time and frequency
> measurement
> Subject: Re: [time-nuts] HP 5345A
> > It probably wandered around much more than that during the year and
> > you just happened to measure it when it was close to the starting
> > point.  Kind of like the broken clock that keeps perfect time every 12
> > hours.  In any event, I can safely say, having looked at thousands of
> > 10811's, that I have never seen one that had anything like that level
> > of aging.
> I thought aging was generally uni-directional and reasonably
> predictable if
> you had enough data.
> Does it wander in both directions?

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