[volt-nuts] HP 3456A AC cal

[M K]

On 12/09/2014 00:30, Richard Moore wrote:
> I'm trying to get my head around the AC cal procedure for the HP 3456A 
> -- there is no full-scale cal, just some extremely finicky tweaks for 
> the bottom ends of three of the four ranges. I really don't understand 
> how this is supposed to work, especially since it is very accurate on 
> all DC ranges (up to 500V -- above that some heating of the divider R 
> seems to occur and it loses accuracy as the voltage increases). But on 
> AC, the tweaks don't result in anything like an accurate level reading 
> compare to my 3458A -- at 10VAC it is off by hundreds of ppm. Anybody 
> shed any light on this? Is there a way to get full scale cal points in 
> AC mode? Any mods to fix this -- lovely meter otherwise; I much prefer 
> it to the 34401A I used to have, except for the overall bigness....
>
Hi Richard,

Does the meter have a DC to RMS converter chip in it, because if it does 
you have to account for the self noise and offset of the gilbert cell at 
the heart of the converter.