I just junked out a very beat up old Fluke 803 differential voltmeter, and found deep within, an old-school Cd/Hg standard cell. It was well protected in an aluminum box, and wrapped in foam and foil. It looks brand-new, and still measures around 1.018... V. I'd like to keep this one as another reference point if it's still good. I assume that it just wasn't used much, or that the Fluke circuits were very good at not loading it down. I'm sure it is the original unit installed in the instrument - marked 5/12/1960. It is a Muirhead D-845-C. There's no test voltage tag or any other info but a serial number. So, I'm wondering if a 52 year old standard cell can still be OK, and if anyone knows the specs on these, or where to find the info. I don't know if it's possible, but I'd like to find what the official voltage was supposed to be to a few more digits resolution. I think various types and brands each had slightly different nominal voltages around that determined by the basic chemistry. I remember in the old days, every one I saw included a sticker with the 25 deg C exact voltage measured as accurately as possible back then against the NBS. I'd like to especially know if this is a saturated or unsaturated cell type. Ed

Hi Ed, The type of cell you have is an UNsaturated type. These types are portable. The saturated type of cells are non-portable and very temperature sensitive requiring the use of a constant temperature enclousure. Here is a web site that describes these devices that is quite good: http://conradhoffman.com/stdcell.htm Bill....WB6BNQ ed breya wrote: > I just junked out a very beat up old Fluke 803 differential > voltmeter, and found deep within, an old-school Cd/Hg standard cell. > It was well protected in an aluminum box, and wrapped in foam and > foil. It looks brand-new, and still measures around 1.018... V. I'd > like to keep this one as another reference point if it's still good. > I assume that it just wasn't used much, or that the Fluke circuits > were very good at not loading it down. > > I'm sure it is the original unit installed in the instrument - marked > 5/12/1960. It is a Muirhead D-845-C. There's no test voltage tag or > any other info but a serial number. > > So, I'm wondering if a 52 year old standard cell can still be OK, and > if anyone knows the specs on these, or where to find the info. I > don't know if it's possible, but I'd like to find what the official > voltage was supposed to be to a few more digits resolution. I think > various types and brands each had slightly different nominal voltages > around that determined by the basic chemistry. I remember in the old > days, every one I saw included a sticker with the 25 deg C exact > voltage measured as accurately as possible back then against the NBS. > I'd like to especially know if this is a saturated or unsaturated cell type. > > Ed > > _______________________________________________ > 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.

http://www.pa4tim.nl/?p=2141. My saturated cells, so you can compare them. I think you have unsaturated ones because saturated ones can not be transported and must be kept in an oven. Most unsaturated cells have a limited lifetime, i read around 10-20 years. Fred PA4TIM Op 30 nov. 2012 om 08:15 heeft WB6BNQ <wb6bnq@cox.net> het volgende geschreven: > Hi Ed, > > The type of cell you have is an UNsaturated type. These types are portable. The > saturated type of cells are non-portable and very temperature sensitive requiring > the use of a constant temperature enclousure. > > Here is a web site that describes these devices that is quite good: > > http://conradhoffman.com/stdcell.htm > > > Bill....WB6BNQ > > > > ed breya wrote: > >> I just junked out a very beat up old Fluke 803 differential >> voltmeter, and found deep within, an old-school Cd/Hg standard cell. >> It was well protected in an aluminum box, and wrapped in foam and >> foil. It looks brand-new, and still measures around 1.018... V. I'd >> like to keep this one as another reference point if it's still good. >> I assume that it just wasn't used much, or that the Fluke circuits >> were very good at not loading it down. >> >> I'm sure it is the original unit installed in the instrument - marked >> 5/12/1960. It is a Muirhead D-845-C. There's no test voltage tag or >> any other info but a serial number. >> >> So, I'm wondering if a 52 year old standard cell can still be OK, and >> if anyone knows the specs on these, or where to find the info. I >> don't know if it's possible, but I'd like to find what the official >> voltage was supposed to be to a few more digits resolution. I think >> various types and brands each had slightly different nominal voltages >> around that determined by the basic chemistry. I remember in the old >> days, every one I saw included a sticker with the 25 deg C exact >> voltage measured as accurately as possible back then against the NBS. >> I'd like to especially know if this is a saturated or unsaturated cell type. >> >> Ed >> >> _______________________________________________ >> 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.

The NBS recorded data on approximately 600 un-saturated cells. About 5% showed an increase of e.m.f. with time, the average
  change being 28 µV/year. The remaining 95% decrease in e.m.f., at an average of 85 µV/year. Of that group, nearly half
  changed by more than 50 µV/year, and one fourth by more than 100 µV/year. That data suggests that certification at
  yearly intervals is required to insure .01% accuracy. The expected life of un-saturated cells is 7-14 years.

Hi, Well from that site the tempco is about 5 microvolts per degree, and from the bottom of the page: The un-saturated cell should have an e.m.f. of 1.0190 volts @ 20°C when new. When the voltage drops to 1.0183 volts, the cell should be discarded, as it is no longer stable. Most reputable labs will not certify a cell below this value. The NBS recorded data on approximately 600 un-saturated cells. About 5% showed an increase of e.m.f. with time, the average change being 28 µV/year. The remaining 95% decrease in e.m.f., at an average of 85 µV/year. Of that group, nearly half changed by more than 50 µV/year, and one fourth by more than 100 µV/year. That data suggests that certification at yearly intervals is required to insure .01% accuracy. The expected life of un-saturated cells is 7-14 years. So my guess would be that it is near the end of its life, but measure and see. MK > Date: Thu, 29 Nov 2012 23:15:19 -0800 > From: wb6bnq@cox.net > To: volt-nuts@febo.com > Subject: Re: [volt-nuts] How long can standard cells last? > > Hi Ed, > > The type of cell you have is an UNsaturated type. These types are portable. The > saturated type of cells are non-portable and very temperature sensitive requiring > the use of a constant temperature enclousure. > > Here is a web site that describes these devices that is quite good: > > http://conradhoffman.com/stdcell.htm > > > Bill....WB6BNQ > > > > ed breya wrote: > > > I just junked out a very beat up old Fluke 803 differential > > voltmeter, and found deep within, an old-school Cd/Hg standard cell. > > It was well protected in an aluminum box, and wrapped in foam and > > foil. It looks brand-new, and still measures around 1.018... V. I'd > > like to keep this one as another reference point if it's still good. > > I assume that it just wasn't used much, or that the Fluke circuits > > were very good at not loading it down. > > > > I'm sure it is the original unit installed in the instrument - marked > > 5/12/1960. It is a Muirhead D-845-C. There's no test voltage tag or > > any other info but a serial number. > > > > So, I'm wondering if a 52 year old standard cell can still be OK, and > > if anyone knows the specs on these, or where to find the info. I > > don't know if it's possible, but I'd like to find what the official > > voltage was supposed to be to a few more digits resolution. I think > > various types and brands each had slightly different nominal voltages > > around that determined by the basic chemistry. I remember in the old > > days, every one I saw included a sticker with the 25 deg C exact > > voltage measured as accurately as possible back then against the NBS. > > I'd like to especially know if this is a saturated or unsaturated cell type. > > > > Ed > >