[time-nuts] hp5061A questions

Frequency Standards & Services chuck at frequencystandards.com
Thu May 26 17:32:37 EDT 2005

Hi George:
        You have a pretty common problem with used cesium's. The first thing
to do would be to look and see if the ion pump current is very high. If it
is, the cesium oven will not turn on. Until the cesium oven is on and
operating at normal temperature, you cannot get any 2nd harmonic or beam
current. The oven should indeed be on all of the time. You will not feel a
great deal of heat on the tube though since it is a double walled tube.
        There isn't a test point that you can measure to tell if the oven is
working correctly since it isn't a simple DC voltage that is applied to the
heater circuit. It is a bridge circuit that uses the heater, a thermistor
and some resistors to balance the tube out at the right temperature.
        The tube would have to have been handled pretty rough to have
damaged the heater element. I wont say it can't happen but isn't likely to
be the problem.
        I am not aware of any web sites that have a manual on them. Perhaps
someone else in the group knows of one.
        I have several "check" procedures that I can send you if you want to
e-mail me direct. They are probably more than what we should post on this
board. They give you steps to check out the unit and tell if you have a
probable bad tube or if there is something else wrong.
        One last word of advice...DON'T adjust ANYTHING on the unit until
you have figured out where your problem is. If you have a really good
standard already then you could use it to check the oscillator with and
adjust it but other wise, leave it where it is for now.
Chuck Norton

Frequency Standards & Services
2727 E. Palmer Park, Ste. 100
Colorado Springs, CO. 80909-3032
719-228-0540  voice
719-228-9009   fax

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
Behalf Of george
Sent: Thursday, May 26, 2005 10:27 AM
To: time-nuts at febo.com
Subject: [time-nuts] hp5061A questions

I just got my first Cesium atomic oscillator (hp5061A) please help!

I dont have a meter reading for the CS oven and believe the oven is not
functioning. The cs oven controler switch is on and set to normal

Shouldn't the CS oven be on all the time like the quartz oven or are
there other signals required before the cesium beam oven activates?

And shouldn't I be able to feel heat from the Cesium beam case
indicating oven operation?

I also have no 2nd harmonic or control readings, all other reading seem
ok, what frequency would the second harmonic be?

I see some test points on a pcb interconnect strip under the bottom
cover ie 18 v  18v  18v  25-30v  synth  control 1mhz  100khz control.
are these control, control test points the same as the mult-meter
control measurement or are these all seperate control voltages for other
functions?  All voltage test points are good. I didn't check synth, or
control test points fearing that a high impedance vtvm would be required

Could someone point me to the supply point for the Cs oven heater
voltage or possibly describe the heater element itself?

Is it delicate enough that coast to coast shipping could have opened the

Are there any online documentation for the hp5061 I can use before
obtaining a service manual?

Also on the cs controler is a pot adjustment labled Mass Spect. What is
this adjustment for.

Thanks for listening.

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