[time-nuts] Cesium standard prices

J. L. Trantham jltran at att.net
Thu Oct 21 01:34:38 UTC 2010


The best place to start is to look at the 5061B manual the operating portion
of which can be found on the internet.

Simple things would be to put the Mode switch in the CS Off position, plug
it in, and then watch the meter indications.

If everything is working correctly, the Supply position should indicate
about 35.  The Battery should be zero since this unit does not appear to
have the optional battery back up installed.  The Ion Pump I may go full
scale but hopefully, given enough time, will come down, hopefully to close
to zero but certainly below 24 or so.  The Osc Oven should go full scale and
in about 30 minutes or so come down on scale, 20-30 or so.  The CS Oven will
be zero along with Mult, Beam I, Control, and 2nd Harmonic.

If these indications are correct, after the Osc Oven stabilizes, put it in
Loop Open and make sure the Mod switch is On.  The CS Oven should go full
scale.  If the Ion Pump I stays below about 24 or so, it will stay there for
20 to 30 minutes or so then come down on scale.  If the Ion Pump I goes off
scale, the CS Oven will shut off until the Ion Pump I comes down below 24 or
so.  Once this occurs, the CS Oven will come back on, full scale, and the
Ion Pump I may again go off scale high again shutting down the CS Oven.
This 'cycling' can go on for hours or days until the tube is 'pumped' down
enough to allow the CS Oven to come on and stay on.

Once the CS Oven is on constantly, the Beam I and the 2nd Harmonic should
come up on scale in 30-40 minutes or so if everything is working OK.  Once
this occurs, put it in Operate, wait about 15 to 20 seconds, then hit the
Logic Reset button.  If all is OK, the Alarm LED will have gone out as the
Beam I and the 2nd Harmonic levels came up and the Continuous Operation LED
will come on when you hit the Logic Reset button.

If all this works, that is good news.  However, to measure the Beam I, you
will need to remove the bottom panel, disconnect P1 from the A7 assembly
and, using an SMB connector on a coax to a 10 Meg input impedance DMM,
connect this cable to the DMM.  Measure the voltage generated on the cable
from the CS tube to the A7 assembly.  From there, I=E/R, and you can
'measure' the Beam Current.

Any failure along the way will result in some prolonged communications to
isolate the problem(s) unless you have some time to read and solve.  I have
found having a GPSDO to precisely set the 5061B's internal 10811 to
precisely 10.00000000 MHz using the Osc Frequency Coarse adjustment with the
X10E-10 control set at 250 is very helpful in trouble shooting these units.

Unless your potential seller is extremely patient and the unit is going to
work right off the bat, you are probably much more likely to do a better job
in your shop with your test equipment handy.  

Perhaps, you could take it out 'on trial'?

Hope this helps.


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Jason Rabel
Sent: Wednesday, October 20, 2010 1:59 PM
To: time-nuts at febo.com
Subject: Re: [time-nuts] Cesium standard prices

I know there was a 5061B listed on Fleabay a couple times and never sold (I
think I even saw it on Craigslist)...

It's located in Houston, TX... IIRC their offices are relatively close to
me, I would be more than willing to drive down there and test out this unit
and report back any numbers / information (as long as someone gives me
step-by-step info). If it works you might be able to work out a deal, if the
tube is dead then maybe you can negotiate a reasonable price.


I'm not associated with the seller at all.. I just remember this being
listed and that it was local (I was halfway tempted to buy it myself but I
really don't need to be spending the money).


> I have noted a couple of units from Australia on ePay for around $200 
> but in unknown condition.
> If you can get a measure of the Ion Pump Current and the Beam Current 
> (which is easy to do if the unit works), the unit becomes more 
> valuable the lower the Ion Pump Current is and the higher the Beam 
> Current is.
> There are a couple of folks on the list that have been very helpful to 
> me in getting to know these units and they may have additional info.

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