[volt-nuts] What's the probability of a random used 3458A passing a Keysight calibration?

[J. L. Trantham]

I agree with the thought that older meters are more stable.  That was confirmed to me by Gary Biermann who worked at Loveland.

In addition, with older meters, getting the latest (or later) firmware is desirable and, depending on the age, there are 'Service Notes' that should be complied with.  The details are on the Keysight website.

Finding the 'sweet spot' is, indeed, the challenge.  I have two HP and one Agilent, all made in the USA.  All had 8,1 firmware.

IIRC, shortly after Agilent came into being, manufacturing moved to Malaysia and switched to SMT technology which then required assembly level replacement rather than component level repair.  

Joe

-----Original Message-----
From: volt-nuts [mailto:volt-nuts-bounces at febo.com] On Behalf Of Dr. David Kirkby
Sent: Tuesday, January 16, 2018 7:48 AM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] What's the probability of a random used 3458A passing a Keysight calibration?

On 16 January 2018 at 13:44, Dr. David Kirkby < drkirkby at kirkbymicrowave.co.uk> wrote:

> Maybe an Agilent meter might be a sweet spot - not as old as an HP, so 
> but less stable than a newer Keysight.
>
> Dave
>

I meant to say, maybe an Agilent meter would not have the reliability problems of an older HP, but be more stable than a new Keysight.

Does anyone know how old the units have to be to reach maximum stability?
Is it the LTZ1000A reference that improves with age, or the ADC? I assume the zener reference, but I don't know.

Dave
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