[volt-nuts] Old muirhead weston cell.

Eldon Johansen eldon.johansen at gmail.com
Sun Sep 12 22:57:56 UTC 2010

Hello, new guy here. 

I recently acquired an old fluke 801 differential voltmeter, and removed
the Muirhead Weston cell from it.
I'm not sure if it is the original cell or not, I don't doubt it.

In any case, it was mounted upside down for what had to be a number of
years, and there are several tiny balls of mercury loose.
Compounding this issue, it does not work right side up, past 30 degrees
from horizontal it is as if it turned off.
My thoughts are this is due to the mercury detaching from the platinum
wire, it works great lying flat on the table.

In any case i took it to work last week and did some measurements,
however the best i could do at the time is verify that it is delivering
1.0190 +/- .05mV volts.
(This was at 18 degrees Celsius)
I'm in the process of building an oil bath and temperature regulator for
it, and by that time i should be able to find the 732b at work and get a
more accurate measurement.

My question is there any good reason why is it nearly half a millivolt
over what the old books say it should be?


Eldon Johansen
eldon.johansen at gmail.com

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