[MyHosting.com]   [KO4BB Home Page]   [Manuals Home Page]   [KO4BB Wiki]

How to check an HP5061A Cesium Standard?

from the [Time-Nuts] mailing list:

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.

Hope this helps.


precision_timing/how_to_check_an_hp5061a_cesium_standard.txt · Last modified: 2013/01/08 19:00 (external edit)
Recent changes RSS feed Creative Commons License Donate Powered by PHP Valid XHTML 1.0 Valid CSS Driven by DokuWiki
Except as noted, this entire site Copyright © 2002-2017. KO4BB All rights reserved.