[time-nuts] Cesium Beam Lifetime

John Miles jmiles at pop.net
Tue Feb 13 22:50:12 EST 2007

In addition to what Didier's saying about the 5370A, there is a 5370B up
there right now (
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=120086699371 ) that'll
probably work OK once the clock-source switch on the back is flipped to INT.
That was the case with another one offered by the same seller recently (
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=120081213010 ).

The earlier 5370B was bought by Dennis Tillman, who is trying to work
through some email problems that have been keeping him off the time-nuts
list.  I pointed him towards the auction when he mentioned he was looking
for a GPIB-compatible counter to monitor some Rb clocks.

Dennis owns at least one of every Tektronix 7000-seies and TM500-series
plugin ever made, but this was his first piece of HP gear, and he complained
that it was wreaking havoc with the feng shui in his shack.  The counter
turned out to have an intermittent glitch or two, as well as some very dirty
front-end switches in both channels, so I felt guilty and insisted on going
through it on the workbench.  Both of those problems went away completely
after I removed the preamp board, took the switches apart, and cleaned the
contacts with Deoxit ProGold.

In that particular counter, someone had replaced the front-end and arming
assemblies with very late-model (circa 1997) boards, but no effort had
evidently been made to calibrate them.  Once this was done, I also went as
far through the interpolator calibration procedure as I could without an HP
8082A pulse generator, which isn't very far.  After all that, the counter
worked reliably and easily met its sensitivity, bandwidth and jitter specs.
The 10811-60111 OCXO was OK as well.

So I imagine the other counter could be a good deal for someone who doesn't
mind a bit of sweat equity.

-- john, KE5FX

> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of Didier Juges
> Sent: Tuesday, February 13, 2007 7:13 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Cesium Beam Lifetime
> Can't help with Cs tubes, but the HP 5370 can do 12 digits/second and
> many other amazing things, such as 20pS resolution time interval in
> single shot, and 0.1pS in repetitive mode.
> This is what I have learned about counters lately...

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