Chuck What exactly would be the extended characteristics on "old" cell that render it no longer useful? Dave NR1Dx On 9/22/2011 8:32 AM, Chuck Harris wrote: > As I understand it, an unsaturated cell that measures 1.0178V is many, > many years > past being useful as a standard, as is any unsaturated cell that > measures below > 1.0183V. > > Saturated cells are very rare outside of laboratory conditions, as > inverting the cell > will ruin it. Unsaturated cells can withstand the topsy turvy travel > conditions > presented by shipping. > > -Chuck Harris > > J. L. Trantham wrote: >> Roy, >> >> The 'experts' are here on the list. From my reading, they have about >> a 50 uV/Yr >> expected decline in value, thus the need for periodic 'calibration'. >> I do not have a >> feel for useful life expectancy but the two I have are in good >> condition and only the >> latest one has a value on the front of '1.01931 @ 20 degrees C' with >> a date on the >> side of '2-4-69'. This AM, it measures 1.017894. However, the 7081 is >> not known to be >> accurate, yet. >> >> The other cell still measures 1.018709 this AM. >> >> So, it would appear that they will make a good standard but will need >> to be measured >> from time to time to generate a log of date, temperature, and value. >> >> I wonder how long it has to be 'still' before it is again stable? >> >> Joe >> >> >> ----- Original Message ----- From: "Roy Phillips" >> <phill.r1@btinternet.com> >> To: "Discussion of precise voltage measurement" <volt-nuts@febo.com> >> Sent: Thursday, September 22, 2011 5:16 AM >> Subject: Re: [volt-nuts] Eppley Standard Cell and What Is It? >> >> >>> 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@att.net> >>> Sent: Thursday, September 22, 2011 2:37 AM >>> To: "Discussion of precise voltage measurement" <volt-nuts@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 >>>> _______________________________________________ >>>> volt-nuts mailing list -- volt-nuts@febo.com >>>> To unsubscribe, go to >>>> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >>>> and follow the instructions there. >>>> >>> >>> >>> _______________________________________________ >>> volt-nuts mailing list -- volt-nuts@febo.com >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >>> and follow the instructions there. >> >> >> _______________________________________________ >> volt-nuts mailing list -- volt-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> and follow the instructions there. >> > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > > -- Dave& Lynn Henderson Manuals@ArtekMedia.com www.Artekmedia.com PO Box 175 Welch,MN 55089

phil sez: Are they worth keeping ? even if not practical, time to get out the cleaners, polish, etc. and put it on the mantel or other display of treasures. any {volt,time,location,etc}-nut must have such a spot or two. -pete On Thu, Sep 22, 2011 at 3:16 AM, Roy Phillips <phill.r1@btinternet.com> wrote: > 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@att.net> > Sent: Thursday, September 22, 2011 2:37 AM > To: "Discussion of precise voltage measurement" <volt-nuts@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 >> _______________________________________________ >> volt-nuts mailing list -- volt-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> and follow the instructions there. >> > > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. >

I don't know exactly, but I suspect that the active materials are expended, or are sequestered, in such a way that they are not available. That would cause the impedance to rise dramatically, and make the reading unstable. -Chuck Harris Artekmedia wrote: > Chuck > > What exactly would be the extended characteristics on "old" cell that render it no > longer useful? > > Dave > NR1Dx

The leads that go through the glass are platinum, that alone makes them worth keeping. Pete Lancashire wrote: > phil sez: Are they worth keeping ? > > even if not practical, time to get out the cleaners, polish, etc. and > put it on the mantel > or other display of treasures. any {volt,time,location,etc}-nut must > have such a spot > or two. > > -pete