[volt-nuts] Eppley Standard Cell and What Is It?

Roy Phillips phill.r1 at btinternet.com
Thu Sep 22 10:16:08 UTC 2011


Joe
Interesting point regarding the "Standard Cell", I have one that was 
purchased some 12 years ago made by Western. It must be well beyond its 
calibrated accuracy. It currently reads 1.018679 volts according to my 
3458A. It seems to be stable but below its original labeled standard (label 
lost). Are they worth keeping ?
Roy


--------------------------------------------------
From: "J. L. Trantham" <jltran at att.net>
Sent: Thursday, September 22, 2011 2:37 AM
To: "Discussion of precise voltage measurement" <volt-nuts at febo.com>
Subject: [volt-nuts] Eppley Standard Cell and What Is It?

> I purchased an eBay item (190538109632) for the 'Standard Cell' that 
> included another item.
>
> What is it?
>
> The 'Standard Cell' is an 'Eppley Laboratory Catalog Number 100 (SN 
> 762058) Low Termperature Coefficient Standard of E. M. F.' that has 
> written on it '1.01931 @ 20 degree C' with a date of what I think is 
> '2-4-69' which I think means Feburary 4, 1969.
>
> Using my 'new' Solartron 7081, I read the voltage at 1.017844 +/- about 1 
> uV.  If I have the math correct, that is a decrease of about 35 uV/yr 
> which, I think, is about what is predicted for these cell's, assuming my 
> 7081 is accurate.
>
> I also have another Eppley Standard Cell (SN 821855) that reads 1.018709 
> but no date or prior reading on the unit.
>
> On another, unrelated note, I have been able to chase down the US branch 
> of Ametek in Oak Ridge, TN, and they will be getting my 7081 back to send 
> to England for calibration and 'service best effort', given that the meter 
> ceased production in 1998 with end of support 2008.  TAT is about 4 weeks 
> in England.
>
> Now, what is that other thing in the listing?
>
> Joe
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