[volt-nuts] HP 3456A AC cal

[John Phillips]

>From what I remember: The 3455A has a good AC front end but is a real pain
to calibrate with a lot of adjustment (read flexibility). I think HP gave
up a lot of accuracy for a simpler calibration. The 3457A seems to do AC a
lot better than the 3456A. Nether meter come close to doing what the 3458A
does.

On Fri, Sep 12, 2014 at 12:04 AM, M K <m1k3k1 at hotmail.com> wrote:

> 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.
>
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-- 

*John Phillips*