Agilent 34401A Ohms does not Zero with a short across terminals -FIXED !!!!

[daveyk]

".. looks fine ... if some time in the future my own, 30 y/o HP34401A will show this error.."

New 500volt relay installed and working perfectly.

[daveyk]

"To some degree, it's a case of "suck it and see". If you keep the traces and leads as short as possible, it'll reduce the chances, at least."

It's not like we are dealing with a high bandwidth instrument.

I replaced the relay with a new 500volt relay that arrives a few hours ago and it is working great again.  I'm shipping it off for calibration in Monday.

[AVGresponding]

True, but with the test current at the higher resistance ranges being only 500nA, it wouldn't take much to add extra noise in there.

Don't forget to let us know how the calibration goes!

[daveyk]

Will do, they just received it today and they can be rather slow.  I had sent one of the Siglent SDG2122X gens with it.  They know I wanted them to hold on to that maybe a month so as to better stagger the gens.  I hope they don't think that about the 34401A - lol, only because I am anxious to see if it passes.

[daveyk]

https://www.mouser.com/ProductDetail/MEDER-electronic-Standex/BT05-2A66?qs=Vo7e0yZOYdGseWOcqf%252B4Ow%3D%3D

.. looks fine ... if some time in the future my own, 30 y/o HP34401A will show this error.. I'll remember this 

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BTW, the meter passed ISO17025 calibration perfectly.  That relay from Mouser worked great with a small adaptor PCB made from perf board.

[daveyk]

True, but with the test current at the higher resistance ranges being only 500nA, it wouldn't take much to add extra noise in there.

Don't forget to let us know how the calibration goes!

No problems passing an ISO17025 Calibration.  Worked great with that Mouser relay.

[daveyk]

I have another 34401A doing the same thing, plus failing "AC" certification (which I never use these meters for).

I just ordered another BT05-2A66 from Mouser to fix this one.  I do not know if that will have anything to do with passing "AC" or not, but if it passes everything else with the ISO17025 certification, I can live with a limited calibration on this one.

If the "AC" is not the relay, and it was just a little out of spec, cannot someone re-calibrated the A/C measeurments with software?

Dave