[volt-nuts] HP-3458A Zero Reading

[Bill Gold]

Randy:

    I sure hope you are not trying to use 26 ga. telephone wire for the zero
shorting wire.  The manual recommends either 14 ga. or 12 ga. solid copper
wire, this is the kind you can get for basic electrical wiring in conduit in
homes, at least in the US.  Generically called "TW" in electrician's
language.

    My 3458A reads about -0.20 uv before AutoCal and less than +0.20 uv
after,  with the short as described in the manual.  You will observe that
the HP/Agilent/Keysight manual for the 3458A does not give any "zero"
stability specs, at least that I can find.

    I have been using the 3458A for nulling my 752A and have had no problems
with my homemade "low thermal" leads as I described them to you.
Belden/Pomona components.  I use 100PLC.

    There is an application note from Fluke, I think, on using DVMs for null
meters.

    "Fluke_-_Using_a_DMM_to_balance_752A_Divider.pdf "  is the name if it.
I think it came from the Fluke
Calibration Website.

Bill



----- Original Message ----- 
From: "Randy Evans" <randyevans2688 at gmail.com>
To: <volt-nuts at febo.com>
Sent: Sunday, July 26, 2015 6:19 PM
Subject: [volt-nuts] HP-3458A Zero Reading


> I shorted the input terminals of my HP-3458A with a short lead of copper
> wire, Bell telephone wire as recommended in the manual.  The reading I get
> is around 000.00070 mV, or 0.7 uV with NLPC set to 100.  I was trying to
> evaluate it's use as a null meter for my Fluke 752A divider.  This seems a
> little higher than I would expect but no amount of running AUTOCAL or ZERO
> changes this amount.  Is this considered acceptable?
>
> Randy AE6YG
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