[volt-nuts] hp3457a low voltage range behavior

J L juris.l at gmail.com
Tue Sep 3 07:55:46 EDT 2013

Hi group !

After long waiting for cheap listing with possibility to european delivery,
at last win 200$ ebay "parts" hp3457a meter.
Now only now need  to find someone local with better equipment to check
calibration :-}

Meter works fine, but I'm not sure how meter must behave in low voltage
If I short leads it show ~1uV, thats Ok.
But if leads not connected then voltage slowly creep up from zero and after
about 5 min
grow to +3v and meter start to click relays trying to autorange.
So look like somewhere inside is ~15GOhm leak to + voltage, i try to clean
board with isopropyl , but no big changes.

So is it normal (I doubt...) , because 10GOhm input impedance, or something
is wrong and need to repair ?
Any input will be appreciated!


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