It's normal. Maybe yours has a little bit higher I-offset than most. But it
is > infinity input impedance on the lowest ranges. You might stick a
parallel 1 G resistor across the input and see what you get.
They are nice meters though.
Tom
----- Original Message -----
From: "J L" <[email protected]>
To: <[email protected]>
Sent: Tuesday, September 03, 2013 7:55 AM
Subject: [volt-nuts] hp3457a low voltage range behavior
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
bands.
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!
Juris
yl3cb
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