HP 6920B Meter Calibrator

Thanks to Hylaphone over on the Antique Radio Forum, I finally have a real meter calibrator.

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The really useful function that I couldn’t otherwise produce in my lab is AC up to 1000 volts. I also suspect the high DC voltages are more stable than my Power Designs model 2K-10 HV power supply.

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Hylaphone did a nice job of recapping it. It checks out to be working fine, but it is a little out of spec according to my (not recently calibrated) HP 3468A, 

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and compared against my Geller 10 volt reference (also not recently calibrated).

HP Agilent Keysight still has a manual scan available on their web site. It has a January 1976 revision date.

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There is also an older manual scan at the HP Archive site with an October 1965 revision date, but that scan has less information and the calibration instructions appear to have at least one error. 

For example, they tell you to connect a scope between test points 1 and 4, with the scope ground on test point 4. That would short out the 12.6 volt DC reference circuit. I think that is a typo and it should have been test points 1 and 2.

On the other hand, the calibration instructions in the newer manual also sound a bit sketchy. It would have you set the inverter phasing by eyeballing the output on a scope. The older manual has a detailed procedure for balancing the DC offset using a scope.

Does anyone have advice on calibrating the 6920B?

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© Steve Byan 2011-2016