[volt-nuts] Quality Multimeters: HP 3457A

[Dr. Frank Stellmach]

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