Old Weston cells
I got my hands on a few very old, unsaturated cells. I figured that they
would be no good after all this time. Just out of curiosity, I measured
them on my 3457A, which hasn't been sent off for calibration yet.
DMM was set to 3 V scale to keep the input impedance high. Room temperature
= 26 C.
Cell #1 = 1.018288
Cell #2 = 1.018236
Cell #3 = 1.018224
I read that when they get below 1.0183 V, they are no good. Is there any
(easy) way to rejuvenate these cells?
Joe Gray
W5JG
Joe,
Do you have any data about prior measurements of these cells or their
history?
I read somewhere there is a predicted decline rate based on time and
temperature IIRC.
Once you get the meter calibrated, you can 'track' their measurements.
Might also be time for a 'differential voltmeter' to add to the 'stable'.
Joe
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On
Behalf Of Joseph Gray
Sent: Monday, August 26, 2013 9:59 PM
To: Discussion of precise voltage measurement
Subject: [volt-nuts] Old Weston cells
I got my hands on a few very old, unsaturated cells. I figured that they
would be no good after all this time. Just out of curiosity, I measured them
on my 3457A, which hasn't been sent off for calibration yet.
DMM was set to 3 V scale to keep the input impedance high. Room temperature
= 26 C.
Cell #1 = 1.018288
Cell #2 = 1.018236
Cell #3 = 1.018224
I read that when they get below 1.0183 V, they are no good. Is there any
(easy) way to rejuvenate these cells?
Joe Gray
W5JG
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.
All my knowledge regarding Weston Cells tells me that is not possible in
any way :-((
2013/8/27 Joseph Gray jgray@zianet.com
I got my hands on a few very old, unsaturated cells. I figured that they
would be no good after all this time. Just out of curiosity, I measured
them on my 3457A, which hasn't been sent off for calibration yet.
DMM was set to 3 V scale to keep the input impedance high. Room temperature
= 26 C.
Cell #1 = 1.018288
Cell #2 = 1.018236
Cell #3 = 1.018224
I read that when they get below 1.0183 V, they are no good. Is there any
(easy) way to rejuvenate these cells?
Joe Gray
W5JG
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.
--
Zbyszek
Sorry, no history at all. They were salvaged from old equipment. From what
I read, they are already below their voltage threshold and should be
tossed. I just thought it would be interesting to measure them anyway.
I think the decline rate was supposed to be around 0.08 uV per year, or
something like that.
After the 3457A is calibrated, I will try to track these three cells, even
though they are supposed to be no longer stable. It will be an interesting
exercise and will only cost me a bit of time. If the cells prove to be
unstable, I can always toss them later. I certainly won't be using them as
any type of standard.
I already acquired a Fluke 845A. It needs some attention, but seems to
mostly work.
Joe Gray
W5JG
On Mon, Aug 26, 2013 at 9:10 PM, J. L. Trantham jltran@att.net wrote:
Joe,
Do you have any data about prior measurements of these cells or their
history?
I read somewhere there is a predicted decline rate based on time and
temperature IIRC.
Once you get the meter calibrated, you can 'track' their measurements.
Might also be time for a 'differential voltmeter' to add to the 'stable'.
Joe
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On
Behalf Of Joseph Gray
Sent: Monday, August 26, 2013 9:59 PM
To: Discussion of precise voltage measurement
Subject: [volt-nuts] Old Weston cells
I got my hands on a few very old, unsaturated cells. I figured that they
would be no good after all this time. Just out of curiosity, I measured
them
on my 3457A, which hasn't been sent off for calibration yet.
DMM was set to 3 V scale to keep the input impedance high. Room temperature
= 26 C.
Cell #1 = 1.018288
Cell #2 = 1.018236
Cell #3 = 1.018224
I read that when they get below 1.0183 V, they are no good. Is there any
(easy) way to rejuvenate these cells?
Joe Gray
W5JG
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
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and follow the instructions there.
I suspected that there was nothing to do to rejuvenate these old cells. I
thought I'd ask anyway.
Thanks.
Joe Gray
W5JG
On Mon, Aug 26, 2013 at 9:16 PM, zbigniew169 zbigniew169@gmail.com wrote:
All my knowledge regarding Weston Cells tells me that is not possible in
any way :-((
2013/8/27 Joseph Gray jgray@zianet.com
I got my hands on a few very old, unsaturated cells. I figured that they
would be no good after all this time. Just out of curiosity, I measured
them on my 3457A, which hasn't been sent off for calibration yet.
DMM was set to 3 V scale to keep the input impedance high. Room
temperature
= 26 C.
Cell #1 = 1.018288
Cell #2 = 1.018236
Cell #3 = 1.018224
I read that when they get below 1.0183 V, they are no good. Is there any
(easy) way to rejuvenate these cells?
Joe Gray
W5JG
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.
--
Zbyszek
volt-nuts mailing list -- volt-nuts@febo.com
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and follow the instructions there.
Are you sure they are unsaturated ? Because most unsaturated cells last only 10-20 years (AFIK). Saturated cells last much longer but they should be kept at 30 degrees celcius for the correct value. On the other hand, as far as I know they do not survive if they are not kept vertical and most of the time they are not when they are kept outside their oven.
I have 4 weston cells in a guildline cabinet with oven. I have the cal data for the first 10 years they have been used. After this time the oven was turned off , the lab was closed but all gear stayed put on that same place over 30 years (the lab was turned into a server room but all the gear just stayed unused ) I made a graph from the data. Took a ruler and extended the lines. After a few months I had a change to measure them with a calibrated 6,5 digit meter and a year later a 7,5 digit meter and the values I found where plus/min a few uV on the lines. But more important the difference between the individual cells was spot on with my graph. So I use them as my house standard (I do not measure them direct. I set my 332 at 10V. A fluke 720 of ESI KV at the value the cell must have. Connect them both to a Fluke 845 and set the 332 so the meter reads zero. Then I check my 731 against the 332 the same way and leave them both connected this way for a few hours. If the meter is still at zero after that time I use the 332 for calibrating a meter.
The only problem is the high Rout of a KV. So I use a buffer made of a LTC1052 and LT1010 after the KV if the multimeter is a 10 M version. But I still wonder if that is needed. I tested it with some meters but did not notice a difference that was within the meters resolution.
Fred, pa4tim
Verzonden met Windows
Van: Joseph Gray
Verzonden: dinsdag 27 augustus 2013 06:26
Aan: Discussion of precise voltage measurement
I suspected that there was nothing to do to rejuvenate these old cells. I
thought I'd ask anyway.
Thanks.
Joe Gray
W5JG
On Mon, Aug 26, 2013 at 9:16 PM, zbigniew169 zbigniew169@gmail.com wrote:
All my knowledge regarding Weston Cells tells me that is not possible in
any way :-((
2013/8/27 Joseph Gray jgray@zianet.com
I got my hands on a few very old, unsaturated cells. I figured that they
would be no good after all this time. Just out of curiosity, I measured
them on my 3457A, which hasn't been sent off for calibration yet.
DMM was set to 3 V scale to keep the input impedance high. Room
temperature
= 26 C.
Cell #1 = 1.018288
Cell #2 = 1.018236
Cell #3 = 1.018224
I read that when they get below 1.0183 V, they are no good. Is there any
(easy) way to rejuvenate these cells?
Joe Gray
W5JG
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.
--
Zbyszek
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to
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These are the type made to put in portable equipment. That should be the
unsaturated type, correct?
Joe Gray
W5JG
On Tue, Aug 27, 2013 at 12:08 AM, pa4tim@gmail.com wrote:
Are you sure they are unsaturated ? Because most unsaturated cells last
only 10-20 years (AFIK). Saturated cells last much longer but they should
be kept at 30 degrees celcius for the correct value. On the other hand, as
far as I know they do not survive if they are not kept vertical and most of
the time they are not when they are kept outside their oven.
I have 4 weston cells in a guildline cabinet with oven. I have the cal
data for the first 10 years they have been used. After this time the oven
was turned off , the lab was closed but all gear stayed put on that same
place over 30 years (the lab was turned into a server room but all the gear
just stayed unused ) I made a graph from the data. Took a ruler and
extended the lines. After a few months I had a change to measure them with
a calibrated 6,5 digit meter and a year later a 7,5 digit meter and the
values I found where plus/min a few uV on the lines. But more important the
difference between the individual cells was spot on with my graph. So I use
them as my house standard (I do not measure them direct. I set my 332 at
10V. A fluke 720 of ESI KV at the value the cell must have. Connect them
both to a Fluke 845 and set the 332 so the meter reads zero. Then I check
my 731 against the 332 the same way and leave them both connected this way
for a few hours. If the meter is still at zero after that time I use the
332 for calibrating a meter.
The only problem is the high Rout of a KV. So I use a buffer made of a
LTC1052 and LT1010 after the KV if the multimeter is a 10 M version. But I
still wonder if that is needed. I tested it with some meters but did not
notice a difference that was within the meters resolution.
Fred, pa4tim
Verzonden met Windows
Van: Joseph Gray
Verzonden: dinsdag 27 augustus 2013 06:26
Aan: Discussion of precise voltage measurement
I suspected that there was nothing to do to rejuvenate these old cells. I
thought I'd ask anyway.
Thanks.
Joe Gray
W5JG
On Mon, Aug 26, 2013 at 9:16 PM, zbigniew169 zbigniew169@gmail.com
wrote:
All my knowledge regarding Weston Cells tells me that is not possible in
any way :-((
2013/8/27 Joseph Gray jgray@zianet.com
I got my hands on a few very old, unsaturated cells. I figured that
they
would be no good after all this time. Just out of curiosity, I measured
them on my 3457A, which hasn't been sent off for calibration yet.
DMM was set to 3 V scale to keep the input impedance high. Room
temperature
= 26 C.
Cell #1 = 1.018288
Cell #2 = 1.018236
Cell #3 = 1.018224
I read that when they get below 1.0183 V, they are no good. Is there
any
(easy) way to rejuvenate these cells?
Joe Gray
W5JG
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.
--
Zbyszek
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To unsubscribe, go to
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To unsubscribe, go to
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and follow the instructions there.
yes then they are for sure unsaturated.
Verzonden met Windows
Van: Joseph Gray
Verzonden: dinsdag 27 augustus 2013 15:17
Aan: Discussion of precise voltage measurement
These are the type made to put in portable equipment. That should be the
unsaturated type, correct?
Joe Gray
W5JG
On Tue, Aug 27, 2013 at 12:08 AM, pa4tim@gmail.com wrote:
Are you sure they are unsaturated ? Because most unsaturated cells last
only 10-20 years (AFIK). Saturated cells last much longer but they should
be kept at 30 degrees celcius for the correct value. On the other hand, as
far as I know they do not survive if they are not kept vertical and most of
the time they are not when they are kept outside their oven.
I have 4 weston cells in a guildline cabinet with oven. I have the cal
data for the first 10 years they have been used. After this time the oven
was turned off , the lab was closed but all gear stayed put on that same
place over 30 years (the lab was turned into a server room but all the gear
just stayed unused ) I made a graph from the data. Took a ruler and
extended the lines. After a few months I had a change to measure them with
a calibrated 6,5 digit meter and a year later a 7,5 digit meter and the
values I found where plus/min a few uV on the lines. But more important the
difference between the individual cells was spot on with my graph. So I use
them as my house standard (I do not measure them direct. I set my 332 at
10V. A fluke 720 of ESI KV at the value the cell must have. Connect them
both to a Fluke 845 and set the 332 so the meter reads zero. Then I check
my 731 against the 332 the same way and leave them both connected this way
for a few hours. If the meter is still at zero after that time I use the
332 for calibrating a meter.
The only problem is the high Rout of a KV. So I use a buffer made of a
LTC1052 and LT1010 after the KV if the multimeter is a 10 M version. But I
still wonder if that is needed. I tested it with some meters but did not
notice a difference that was within the meters resolution.
Fred, pa4tim
Verzonden met Windows
Van: Joseph Gray
Verzonden: dinsdag 27 augustus 2013 06:26
Aan: Discussion of precise voltage measurement
I suspected that there was nothing to do to rejuvenate these old cells. I
thought I'd ask anyway.
Thanks.
Joe Gray
W5JG
On Mon, Aug 26, 2013 at 9:16 PM, zbigniew169 zbigniew169@gmail.com
wrote:
All my knowledge regarding Weston Cells tells me that is not possible in
any way :-((
2013/8/27 Joseph Gray jgray@zianet.com
I got my hands on a few very old, unsaturated cells. I figured that
they
would be no good after all this time. Just out of curiosity, I measured
them on my 3457A, which hasn't been sent off for calibration yet.
DMM was set to 3 V scale to keep the input impedance high. Room
temperature
= 26 C.
Cell #1 = 1.018288
Cell #2 = 1.018236
Cell #3 = 1.018224
I read that when they get below 1.0183 V, they are no good. Is there
any
(easy) way to rejuvenate these cells?
Joe Gray
W5JG
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.
--
Zbyszek
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