[volt-nuts] hp3457a low voltage range behavior
tmiller11147 at verizon.net
Tue Sep 3 09:24:22 EDT 2013
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.
----- Original Message -----
From: "J L" <juris.l at gmail.com>
To: <volt-nuts at febo.com>
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
> 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
> 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
> is wrong and need to repair ?
> Any input will be appreciated!
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