[volt-nuts] Quality Multimeters: HP 3457A

Roy Phillips phill.r1 at btinternet.com
Mon Aug 3 09:32:47 UTC 2009


Hello Frank
Thanks for you assessment of the "quality" DVM's - - I also have a 34401A, 
but I have never been confident that it was in the "quality" league. This is 
probably because of the opinion of a dealer, who considered it to be 
inferior,  and perhaps the fact that it has been discontinued, although this 
latter factor is probably more to do with marketing. But I had not realized 
that its design was based upon the 3458A, I will now consider having it 
checked for calibration. A considerable number of 3457A's have been 
available in the UK, as I gather that it was widely used as a system DMM by 
the various military organizations - but you are right - it is aging now, 
despite the fact that it uses two processors !
I will continue with the quest for a 3458A.
Thanks for your suggestions regarding the "home made" voltage standard - I 
have seen the LTZ1000A mentioned on many occasions.



----- Original Message ----- 
From: "Dr. Frank Stellmach" <drfrank.stellmach at freenet.de>
To: <volt-nuts at febo.com>
Sent: Sunday, August 02, 2009 8:50 PM
Subject: [volt-nuts] Quality Multimeters: HP 3457A


Hello Roy,

take into account the 34401A also, as the spec (stability) are very
similar to the 3457A.
The 3457A has some extended DCI ranges, compared to the 34401, but also
no complete ACAL feature, as the 3458A.

I have in mind, that the 3457A may also be used in 7 1/2 digit mode, but
could not find this in the manual.
The 34401A can deliver more digits than 6 1/2 via GPIB
Linearity is 2ppm, but the 3457A is not specified at all in this regard.

Seems to me, that the 3457A is an elderly design, discretely built, and
has not been so common.

The 34401A design is derived from the 3458A, more compact and ruggedized.


Anyhow, better go for the 3458A.
ACAL, its stability and precision, the complete set of current ranges,
the different possibilities to make high precision AC measurements, and
the digitizing fetures are all worth the money.

I was lucky to pick a 9 year old unit here in Germany for about 3000€
recently.

I built a LTZ1000A based, dual reference, as a replacement of Fluke 732A
/ 732B or  7001.
Short term stability (1h) compared with the 3458A is around 2e-7.

Then I added a one decade precision divider for linearity testing (like
a 720A), and a 10:1, 100:1 reference divider, like the 752A.

Mentioned commercial devices are also rare here, but if you find them,
they are too expensive in most cases here in EU. I think, the US market
would be a better place to acquire them, despite tax & toll.


The analogous device to the time-nuts cesium clock would be a Josephson
array plus HF-devices plus liquid helium. It's a pity that "volt" cannot
be transferred wireless also..

Frank Stellmach

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