[volt-nuts] (New to me) 3458A Trivia

[J. L. Trantham]

Per my conversation with Gary Biermann, the 4 ppm and the 2 ppm units are
the same as the 8 ppm units except they perform better.  Purely a selection
of best performers and nothing to do with a special circuit.

I don't know about Fluke.

Joe

-----Original Message-----
From: volt-nuts-bounces at febo.com [mailto:volt-nuts-bounces at febo.com] On
Behalf Of John Phillips
Sent: Tuesday, October 30, 2012 11:07 AM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] (New to me) 3458A Trivia

I think the main thing they do is age and screen.

On Tue, Oct 30, 2012 at 6:48 AM, Bill Gold <wpgold3637 at att.net> wrote:

> Speaking of the 03458-66529 reference board added to the HP 3458A by 
> Fluke (before Fluke offered the 8508A), has anyone ever seen a 
> schematic of that board or how Fluke could rate that reference at 2 
> ppm?  One person on this forum theorized that by lowering the 
> operating temperature of the LTZ1000A to around 70 degrees C, which is 
> what the LTC device specification note recommends, this might have 
> what was done to achieve the better drift specification.  It was noted 
> that HP was running the LTZ1000A at around 105 degrees C which might 
> accelerate the aging rate.  I lowered my references to around 70 C and 
> they have seemed to be a little more stable when checked against the 
> Fluke 732A DC Reference Standard.  But I never started a project to 
> follow up on this theory.  Just another project to play with when I "get a
round toit"
> Bill
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--
John Phillips
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