[volt-nuts] HP 3458A

[gbusg]

Your argument would be valid where Type A Uncertainty and/or drift are the 
dominant contributors to a specification. However that's not the case for 
the HP/Agilent 3458A, where Type B Uncertainty is the dominant contributor. 
Over the past 21 years metrology labs and National Metrology Institutes have 
successfully used this fact to their advantage by using 'Golden' 3458As in 
order to reduce the propagation of Type B Uncertainty in their state-of-art 
applications.

This is the same technique used by the same labs to reduce propagation of 
Type B Uncertainty in their state-of-art processes for other devices like 
attenuators, thermal converters and power sensors, etc.

That this opportunity exists with the 3458A speaks very highly of it.

Keep in mind that, for all such 'golden' processes, it's necessary to use 
the standards labs' measurement data (of your 'golden' instrument) as 
correction factors in your processes.

If you're not actively involved (with state-of-art processes requiring such 
reduction of the propagation of Type B Uncertainty) - and if you're not 
actively using a 3458A in a state-of-art application like this - then don't 
worry about it.

http://lvldstdslabagilent.blogspot.com/2005/01/faq-what-3458a-calibrations-are.html

http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1989-04.pdf


-Greg


----- Original Message ----- 
From: "WB6BNQ" <wb6bnq at cox.net>
To: "Discussion of precise voltage measurement" <volt-nuts at febo.com>
Sent: Saturday, August 06, 2011 6:13 PM
Subject: Re: [volt-nuts] HP 3458A


This response illustrates the absurdity in the whole process.  The so-called
"Golden Calibration" is only of value in shifting from a fixed standard to 
an
instrument that can measure "in-between" values to a high degree if done 
within
minutes of the set up.  It is called the transfer ratio and is the 24 hour
specification.

The absurdity to think your going spend additional money for the "Golden" 
part
and get something is total BS.  Even the STE/9000 is the value at the time 
of
calibration.  Bouncing around in shipping could certainly invalidate that 
value.

Such antics could best be described as the cat chasing his tail.

Bill....WB6BNQ