[volt-nuts] Accurary and performance : any experience with the HP 34420A ?

Marvin E. Gozum marvin.gozum at jefferson.edu
Thu Aug 26 11:41:53 UTC 2010

Hello Sam,

I do not own the 34420, but looked at the 34420A some time ago.

It comes down to resolution versus accuracy.

The 34420 can resolve to 1pV while the 3458a to 10nV. But the 34420 
is ~ 20 ppm, at 10Vdc, 90 days.  Its other ranges span between 
20-60ppm for 90 days.  You can compare accuracy on your own from 24h 
up to 1 year, as their spec sheets provide.

For the same time frame, the 3458a is 4.6 ppm, and between 4-6ppm for 
all the Vdc scales, and this is without the high accuracy board.

As the last digits of all meters are the subject of most of the 
uncertainty, without tight accuracy, you repeat the measurement, you 
don't want to get something else.

As Bruce suggests the 34420 is a modified 34401, its basic platform 
has limitations.

At 05:09 PM 8/25/2010, Samuel DEMEULEMEESTER wrote:
>Hi guys,
>I read carefully all your debates about the voltage references and internal
>constructions of the famous 3458A or 34401A, but I wonder why nobody ever
>speaks about the 34420A. According to the datasheet, it seems to outperform
>the 3458A with small signal measurements. Does anybody have some experience
>with this meter or know what's inside ? Is it a tuned 34401A or something
>different ?
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Marv Gozum
Philadelphia, PA  

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