[volt-nuts] Fluke 5200A instability... A resolution...

[John Phillips]

The HP 3455A had a much better AC section but it was a pain to cal.

HP work hard to make cal easy and settled for a weak AC converter so they
could do a closed case cal.

The 3455A, 3457A and 3458A all integrate at line frequency and all have a
better AC converter.

Integration is tied to line frequency to cancel line noise not to have the
interrogator more accurate at what ever integration frequency.

Integration time is also used for all the measurements not just the AC
converter.

3457A is a better meter than the 3456A but people do not seem to respect
it. It may be the display but it is the first of the HP meters to do stats.
You may be able to find a 3457A for about or less money than a 3456A It
will be a lot easier to carry as well.





On Thu, Aug 27, 2015 at 10:50 AM, Chuck Harris <cfharris at erols.com> wrote:

> Hi David,
>
> I don't mind so much the journey, as I do being disappointed
> in the performance of the HP3456A's AC section.  DC and Ohms,
> it is a wonderful DVM.  AC, not so much.
>
> Since it times its integrators to the power line frequency, it
> is dooming itself to work stably only at those exact frequencies.
>
> Wouldn't it have been better to arrange things so that the
> integrator randomly frequency hopped about a range of frequencies?
>
> With computer control, it should be fairly easy to compensate for
> the differing integration times such a scheme would require...
> even back then.
>
> -Chuck Harris
>
>
> David C. Partridge wrote:
>
>> Chuck I so feel for you one this one.  I almost went down the exact same
>> rabbit hole about two years back when I didn't set the AC Filter to ON on
>> my
>> 7081.
>>
>> Luckily I didn't get very far down the "my 5200A isn't working" track
>> before
>> I was reminded by a friend that I needed to turn on the filter for <400Hz
>> signals.
>>
>> Cheers
>> Dave
>>
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-- 

*John Phillips*