[volt-nuts] AC Voltage Measurement Standards

Todd Micallef tmicallef at gmail.com
Tue Jul 8 22:48:17 EDT 2014


I have the above listed models. My opinion of the 540B is that it requires
a lot of work. Reading the manual, it suggests swapping cables for
repeatability to get a good reading.

It originally shipped with a mercury cell for the galvanometer so you may
get a D sized dead/leaking battery. It also has a large Ni-Cd pack for
operation since it is not recommended for use while plugged in. There is no
proper battery charging circuit so you will have to monitor the charge
time. Also, there appears to have been two versions of the plug-in unit.
They are either A54-1 or A54-2. I cannot tell you the difference between
the two. I think that the A54-2 had better input protection.

Hopefully you can get one with a good thermal element that has not been
blown out. There is a procedure on EEVblog for determining if the thermal
element is not damaged.
I found a link a few months ago where Transmille was using the input port
for the A55 thermal converters as an output line. They connected the output
to different 8.5 digit multimeters to characterize an AC source.

My 8506A's are very nice. They are spec'd to 1Mhz and make a good second
7.5 digit DC meter too. Unfortunately, you cannot do AC current
measurements without using external shunts like the A45 series.

I have two different A55 thermal converters, but they have not been
thoroughly tested. I would recommend getting the Ballantine 1395A/B thermal
converters as they appear to be better supported by cal labs. I think
Ballantine still sells them and will do repairs and calibrations.

My other favorite is the Fluke 8920A. I think it is a good meter. It's 3.5
digit display is augmented by a DC analog output that you can connect to an
external meter. The 8920A is recommended for calibrating the 5100B series
wideband output.

Another potential AC measurement standard would be the Datron/Wavetek 4920
or 4950 reference standards. The cost to calibrate from Fluke is
astronomical though. You can look up the pricing on their website to see
what they charge. $3K-4K if I remember correctly.

Before I sent my 3458A in for calibration, the NVRAM was changed and I
performed the SCAL using my 5100B and 8920A. I was able to get the cal to
pass and was very surprised when Gary Bierman told me that all tests passed
during calibration.

I think you should consider getting both the 8506A and 8920A. Pick up a set
of shunts whenever you can get a good deal.


On Tue, Jul 8, 2014 at 9:46 PM, J. L. Trantham <jltran at att.net> wrote:

> I've been thinking about adding an AC Voltage Measurement Standard to my
> shop.
> It would appear that most of these have to do with thermal converters.
>  Does
> anyone have any thoughts about this?
> I've been thinking about a Fluke 540B, 8506A, or a collection of A55
> Thermal
> Converters.  I have accurate DC measurement tools and DC standards.
> I would appreciate any thoughts.
> Thanks in advance.
> Joe
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