[volt-nuts] Fluke 5200A AC Calibrator

[J. L. Trantham]

David,

As you said, to the man with one watch ...........

You need a reference.  Which do you believe to be the best?  Get it (or
more) calibrated.  Aren't you near Ametek?

I have a 7081 and two 3458A's with all just back from calibration from their
respective companies.  I now have three different answers.

The two 3458A's are in the midst of an experiment with programming and
therefore have not been in a 'controlled environment' at this time.
However, it seems to me that I am going to have to repeat the calibration
cycle in a year or so and see how the three compare after that.

I tend to believe the 7081 on the basis that I used it as a 'transfer'
standard' to 'home cal' one of the 3458A's.  When the 3458A got back from
Agilent, it was within spec on all the ranges that I used the 7081 as the
'transfer standard'.  

Good luck.

Joe


-----Original Message-----
From: volt-nuts-bounces at febo.com [mailto:volt-nuts-bounces at febo.com] On
Behalf Of David C. Partridge
Sent: Tuesday, March 20, 2012 10:48 AM
To: 'Discussion of precise voltage measurement'
Subject: [volt-nuts] Fluke 5200A AC Calibrator

I just recently managed to buy a spares unit for my 5200A.

I'm delighted to report that between the two units, and after a bit of
trouble de-soldering edge connectors, I now have a working, quiet (old fan
was DEAFENING), but uncalibrated AC calibrator.

Checking the output is against my 7081, here is what I'm see on the 1V range
set for 1V (the other ranges show a very similar pattern):

 Frequency  Reading    Error
 50Hz       1.00371    .371%  <--- Surprisingly high 
 100Hz      1.00091    .091%  <--- Surprisingly high 
 500Hz       .99993    .007%
 1kHz        .99990    .010%
 5kHz        .99991    .009%
 10kHz       .99991    .009%
 50kHz      1.00004    .004%
 100kHz     1.00003    .003%
 500kHz      .99718    .282%
 1MHz        .98859   1.140%	<--- This seems very high

Comparing the results against a 7150Plus which was connected in parallel, I
get a different story:

 Frequency  Reading    Error
 50Hz        .99993    .007%  *** see below
 100Hz       .99989    .011% 
 500Hz       .99991    .009%
 1kHz        .99991    .009%
 5kHz        .99993    .007%
 10kHz       .99993    .007%
 50kHz      1.00028    .028%
 100kHz      .99933    .077%

Substituting a 7151 for the 7150Plus I get:

 Frequency  Reading    Error
 50Hz        .99986    .014%  *** see below
 100Hz       .99992    .008% 
 500Hz       .99997    .003%
 1kHz        .99997    .003%
 5kHz        .99997    .003%
 10kHz       .99995    .005%
 50kHz      1.00002    .002%
 100kHz      .99895    .105%


These figures are quite impressive for the 7150Plus and the 7151 as the 24
hour figures for the 7150Plus are 40Hz-10kHz range are .03% + 15 counts and
the one year figures are .07% + 15 counts.  The 7151 figures are similar.

(***) I was only able to get a stable reading at 50Hz by grounding the low
output of the calibrator.  I'm not quite sure what the problem is here.

If I believe the 7150Plus or the 7151, the calibrator is correct within the
limits of the meters' accuracy.

If I believe the 7081, the calibrator is way off at the low end and high end
of the frequency ranges.

Hmmmm ...

Does anyone have any suggestions as to why the 7081 seems to read so high at
50Hz, 100Hz and 1MHz, and whether the calibrator is wrong or the 7081?

Oh dear, life was so much simpler when I only had one clock!!!

Dave


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