Fluke 732A Questions
Todd,
I found the MSC1983.PDF document with no trouble. Thanks for the info.
Can't wait to see the 'change sheets' for the 732A. Where did you find your
732A manual? Mine is the one on the Fluke website, P/N 645051, for the
732A, not 732A/AN. I'll have to search for that.
Happy New Year.
Joe
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On
Behalf Of T. Micallef
Sent: Sunday, December 29, 2013 10:04 PM
To: volt-nuts@febo.com
Subject: Re: [volt-nuts] Fluke 732A Questions
Joe,
I don't know if it makes any difference but my manual is for the 732A/AN p/n
788414
I found a couple of brochures that I scanned and uploaded too.
I forgot to mention, I have been collecting information regarding the
techniques used to do intercomparisons using scanners like the Data Proof
models. While searching a couple of weeks ago, I came across an old document
from a Measurement Science Conference back in 1983. The document contains an
article regarding the testing of the Fluke 735C. I thought you may have
little to no info regarding your reference and thought I would let you know
about it.
The document is easy to find using google. It is named MSC1983.pdf I will
upload it as well, but I was not sure if Didier wants to track conference
docs.
Todd
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.
My manual came from manualsplus. It was in excellent condition compared to
the ones on eBay. You do have to ask them for a picture of every manual
since they can vary in condition.
I have rescanned the whole manual, which I should have done anyway.
I have two missing pages and I am hopeful the seller will scan them and
forward them to me.
Todd
Joe:
My 732A units vary in thermistor resistance from 3.408K ohms to 4.514K
ohms and have been extremely stable to with in +/- 5 ohms for years now. I
did measure the oven temperature of the one with the 3.408K ohms just to see
what was causing the thermistor resistance to be a little low and came up
with about 47 degrees centigrade, as best as my equipment would allow me to
measure it. Equipment was a Fluke 80TK thermocouple module, a Fluke 80 PK-1
thermocouple bead and a HP 3456A DVM. I put shrink wrap around the bead and
then threaded the bead into the temperature oven through one of the
adjustment holes in the front panel and made sure that it was far into the
oven, probably around the middle. Then I checked another unit that read
4.5K ohms and it read around 43 degrees C so all of that made sense. I
believe I saw somewhere that the spec was 45 degrees C +/- 2 C.
I did have to change the jumpers on the "Calibration PCB Assembly" on
one of my units so that it would match other 732A units that were "In Cal"
and had certified values. But that unit has since drifted down at a rate of
around 1.2 ppm per year which is with in specs but a little more than I have
seen from other units. Recently this unit has suddenly quit drifting down
and seems a lot more stable now. That was S/N 459xxxx. I have a S/N
343xxxx which has been proven rock solid for years now at around +/- .3 ppm
and just seems to have "DC noise" stability as it just goes up a little and
then down a little and never needed any adjustment. I also have a S/N
460xxxx which is extremely stable also. So I guess that age does seem to
factor into stability as well as how long they have been powered up. But
the only way to insure that you have a good "volt" is to have at least 4
units and then inter-compare them periodically following NIST (NBS)
Technical Note #430. While 430 was written for Saturated Standard Cells,
the technique seems to work just fine at 10 volts also. You can also find
this measurement technique in the 1st Fluke "Calibration - Philosophy in
Practice" book published around 1974.
I gave up on the "unobtainium" connector on the back of the battery pack
very quickly. I drilled a 1/4 " holes on either side of the "unobtainium"
connector, after removing it, and used two single miniature banana jacks to
allow me to connect to the batteries for the purpose of checking their
performance as described in the 732A manual page 2-9 in manual P/N 788414
May 1986. I should probably turn in my resignation as a "volt nut" for this
action but it works. KISS.
Bill
----- Original Message -----
From: "J. L. Trantham" jltran@att.net
To: volt-nuts@febo.com
Sent: Saturday, December 28, 2013 2:51 PM
Subject: [volt-nuts] Fluke 732A Questions
I have reviewed the prior postings on Volt-nuts (a very rewarding review,
BTW)) regarding the 732A and have two questions:
-
Has anyone determined the part number, or a source, for the
mating
plug to J10, the external power connector for the 732A-7005 battery pack?
I
noted some postings recently about this but did not find a definitive
response regarding the identity of this plug. The alternative would
appear
to be a complete replacement of J10 and its plug, as long is it all fits
in
the opening in the panel. I hate to 'bore holes' in vintage equipment.
-
The oven thermistor in my 'new to me' unit measures 4229 ohms
(+/-
an ohm or two) after the unit has warmed up for a week or so. I note the
manual refers to 3K to 4K for the value of this thermistor when the unit
is
'stable' as well as other's posting values in the mid 3500's ohms for
their
units. Should I be concerned? The unit seems to be stable to within
about
2 uV over about a week (as measured by my 3458A - see below). Should I
open
the unit and try to measure the oven temperature or just be satisfied that
the unit seems to be working?
I had to replace the four 6V 4AH SLA batteries and they charged up
appropriately as judged by the front panel LED's. I had to remove the
'jumper' for the '40' option on the A7 board and connect the jumper to the
'20' and '10' options (total of '30') in order to get the unit to adjust
to
10.0000000 VDC on my 'Agilent In Cal'd' 3458A.
The need to change the jumpers, perhaps, could be just an ageing issue or,
on the other hand, a 'temperature' issue with the oven.
Should I open the unit and directly measure the temperature (supposedly
about 48 degrees C) or just be satisfied with what I have?
My recently added 735C also needed moving some 'jumpers' in order to get
it
'on scale', as determined by my 3458A, although it's thermistor measures
about 3330 ohms (after being on for several weeks).
Thanks for everyone's help.
Joe
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to
and follow the instructions there.
I called them this AM and they only had a 'copy' of the manual and not an
original.
If I understand what you are saying, you got a copy as well.
If so, were the 'change sheets' part of the 'copy'? When I asked about
that, I was told that there were no 'change sheets' in the copy she was
looking at when I called and asked about condition and change sheets.
Joe
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On
Behalf Of T. Micallef
Sent: Monday, December 30, 2013 1:06 PM
To: volt-nuts@febo.com
Subject: Re: [volt-nuts] Fluke 732A Questions
My manual came from manualsplus. It was in excellent condition compared to
the ones on eBay. You do have to ask them for a picture of every manual
since they can vary in condition.
I have rescanned the whole manual, which I should have done anyway.
I have two missing pages and I am hopeful the seller will scan them and
forward them to me.
Todd
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.
Bill,
Sounds like you are further along in the 'volt-nut' process than I am. I'll
have to chase down the NIST paper. I have been very impressed by the
stability of the 732A and the 735C.
Unfortunately, I don't have any documentation on the 735C and only the early
manual for the 732A.
I would be interested in the specifics of the battery check procedure in
your manual. Unfortunately, my manual does not have a page 2-9.
I note that there are two banana jacks on the front of the battery module,
both black, one connected to ground and the other not connected to anything.
Any idea of what they are for?
I always like to keep equipment as 'original' as possible. If I can't find
the correct connector, I'll find something similar that will fit in the same
hole and use it instead. We'll see what I hear from Fluke and Hypertronics.
Also, how do you get your 732A calibrated? Do the batteries last long
enough to ship overnight to a facility?
Thanks for the info.
Joe
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On
Behalf Of Bill Gold
Sent: Monday, December 30, 2013 7:03 PM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Fluke 732A Questions
Joe:
My 732A units vary in thermistor resistance from 3.408K ohms to 4.514K
ohms and have been extremely stable to with in +/- 5 ohms for years now. I
did measure the oven temperature of the one with the 3.408K ohms just to see
what was causing the thermistor resistance to be a little low and came up
with about 47 degrees centigrade, as best as my equipment would allow me to
measure it. Equipment was a Fluke 80TK thermocouple module, a Fluke 80 PK-1
thermocouple bead and a HP 3456A DVM. I put shrink wrap around the bead and
then threaded the bead into the temperature oven through one of the
adjustment holes in the front panel and made sure that it was far into the
oven, probably around the middle. Then I checked another unit that read
4.5K ohms and it read around 43 degrees C so all of that made sense. I
believe I saw somewhere that the spec was 45 degrees C +/- 2 C.
I did have to change the jumpers on the "Calibration PCB Assembly" on
one of my units so that it would match other 732A units that were "In Cal"
and had certified values. But that unit has since drifted down at a rate of
around 1.2 ppm per year which is with in specs but a little more than I have
seen from other units. Recently this unit has suddenly quit drifting down
and seems a lot more stable now. That was S/N 459xxxx. I have a S/N
343xxxx which has been proven rock solid for years now at around +/- .3 ppm
and just seems to have "DC noise" stability as it just goes up a little and
then down a little and never needed any adjustment. I also have a S/N
460xxxx which is extremely stable also. So I guess that age does seem to
factor into stability as well as how long they have been powered up. But
the only way to insure that you have a good "volt" is to have at least 4
units and then inter-compare them periodically following NIST (NBS)
Technical Note #430. While 430 was written for Saturated Standard Cells,
the technique seems to work just fine at 10 volts also. You can also find
this measurement technique in the 1st Fluke "Calibration - Philosophy in
Practice" book published around 1974.
I gave up on the "unobtainium" connector on the back of the battery pack
very quickly. I drilled a 1/4 " holes on either side of the "unobtainium"
connector, after removing it, and used two single miniature banana jacks to
allow me to connect to the batteries for the purpose of checking their
performance as described in the 732A manual page 2-9 in manual P/N 788414
May 1986. I should probably turn in my resignation as a "volt nut" for this
action but it works. KISS.
Bill
----- Original Message -----
From: "J. L. Trantham" jltran@att.net
To: volt-nuts@febo.com
Sent: Saturday, December 28, 2013 2:51 PM
Subject: [volt-nuts] Fluke 732A Questions
I have reviewed the prior postings on Volt-nuts (a very rewarding review,
BTW)) regarding the 732A and have two questions:
-
Has anyone determined the part number, or a source, for the
mating
plug to J10, the external power connector for the 732A-7005 battery pack?
I
noted some postings recently about this but did not find a definitive
response regarding the identity of this plug. The alternative would
appear
to be a complete replacement of J10 and its plug, as long is it all fits
in
the opening in the panel. I hate to 'bore holes' in vintage equipment.
-
The oven thermistor in my 'new to me' unit measures 4229 ohms
(+/-
an ohm or two) after the unit has warmed up for a week or so. I note the
manual refers to 3K to 4K for the value of this thermistor when the unit
is
'stable' as well as other's posting values in the mid 3500's ohms for
their
units. Should I be concerned? The unit seems to be stable to within
about
2 uV over about a week (as measured by my 3458A - see below). Should I
open
the unit and try to measure the oven temperature or just be satisfied that
the unit seems to be working?
I had to replace the four 6V 4AH SLA batteries and they charged up
appropriately as judged by the front panel LED's. I had to remove the
'jumper' for the '40' option on the A7 board and connect the jumper to the
'20' and '10' options (total of '30') in order to get the unit to adjust
to
10.0000000 VDC on my 'Agilent In Cal'd' 3458A.
The need to change the jumpers, perhaps, could be just an ageing issue or,
on the other hand, a 'temperature' issue with the oven.
Should I open the unit and directly measure the temperature (supposedly
about 48 degrees C) or just be satisfied with what I have?
My recently added 735C also needed moving some 'jumpers' in order to get
it
'on scale', as determined by my 3458A, although it's thermistor measures
about 3330 ohms (after being on for several weeks).
Thanks for everyone's help.
Joe
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to
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 received the manual with the plastic gray cover just like many of their
newer manuals. It appears to have sat on a shelf with little use. No user
notes have been found. The changes are part of the manual as an additional
section in the back.
I suspect that since it wasn't used much, no one noticed the missing pages.
Even the two brochures were in immaculate condition.
I am guessing that maybe their copies are from my original and are missing
the pages in question (4-9 through 4-12). Since I didn't get a response from
them, I will call in the morning since I am in need of another manual.
Todd
Joe wrote:
Also, how do you get your 732A calibrated? Do the batteries last long
enough to ship overnight to a facility?
No -- I assumed that was why you were looking for a battery
connector. You install an external battery for shipment
overnight. Fluke can supply a complete external battery with cable
and plug ($375, last I knew), or you can make your own. I believe
they can also supply a shipping container, which has a dedicated
space for the Fluke external battery. (If you don't use Fluke's
container, build something very sturdy with wood and padding and with
handles that make it hard not to carry it and set it down right side up.)
I wouldn't have anybody but Fluke calibrate a 732A. There are 3
levels of calibration, all with data, from about $700 to about $1500
(the last is calibration by Fluke's Primary Standards Lab).
As far as thermistor values go, the relevant question is not what is
the value in absolute terms, but rather what is the value in relation
to the "as manufactured" value, which was provided by Fluke when the
unit shipped. This had been recorded by the original owners of each
of my units, and they are all within 2 ohms of the original value today.
If you do not know the original value, then your original measurement
is a "going forward" value and it cannot tell you anything about
where you are in relation to the original manufactured value. The
fact that you had to change cal jumpers suggests that either the oven
temperature has shifted since manufacture, the reference assembly has
shifted, or both.
Fluke has said various things in various places about how far the
thermistor readings can drift before you have a problem. +/- 20 ohms
over the unit's lifetime seems to be a good consensus value. If it
changes fast -- say, 10 ohms or more in a month -- you have a problem.
Best regards,
Charles
Charles,
I would like to find the mating plug for J10 for several reasons, being able
to get it to calibration being just one of them. However, I was hoping it
would be good enough to make it to calibration on the internal batteries.
I seem to recall reading that the internal batteries were good for a few
hours but nothing like what the 732B would do, which sounded like the 732B
could make the trip on the internal batteries.
Where did you find the resistance of the thermistor 'as shipped'? I saw
mention of being supplied to the original owner when shipped as well and I
have had the top cover off and the battery module out to replace the
batteries and found nothing to suggest a thermistor value. I have also
lifted the top layer of insulation off the oven to move the cal-jumpers but
did not see anything that suggested a thermistor value.
My 'metrology level' standards are my HP 3458A's, calibrated by Agilent, and
Solartron (Ametek) 7081's calibrated by Ametek. I have been thinking of
getting the 732A calibrated by Fluke but I didn't know if they would still
calibrate the unit. I wonder if they would have the 'as shipped' thermistor
value on file for my specific serial number?
I, too, read about the stability of the thermistor being the most important
measurement. That was in the 'change sheets' attached to the manual on
Didier's site.
The 'cal-jumper' was at '40' when I got the unit. Per my 3458A, I could
only get it down from about +220 uV to about +100 uV with the front panel
adjustment. By moving the jumper to '20', I could only get it up to about
-12 uV below 10 V by turning the adjustment all the way in the opposite
direction. However, by connecting jumpers for both the '20' and '10', I was
able to get it at 10 V with the front panel adjustment at about center
position. I have not 'logged' any values yet but every time I go to the
shop, it is about +/- 1 or 2 uV from 10 V. I do the 'AUTO CAL' on the 3458A
each morning I go into the shop.
I measure the resistance with a Fluke 8050A (simply because it is the
closest DMM to the standard) and it is 4229 to 4230 ohms each day.
Interestingly, when I got the 732A, undisturbed Fluke Calibration stickers
were in place over each of the adjustments on the front panel, on a back
screw on the top cover, and 'half' of a sticker on the back over the power
supply module, as if the other half was lost when someone removed the
battery module. Somehow, I find that comforting, given that it now seems so
stable, making me think it is 'normal aging' that is responsible for the
values I measured rather than a problem with the oven, etc.. IIRC, the spec
is 6 ppm per year for 10 V, or 60 uV per year. I'll have to look at the
power supply module to see if I can find some date codes but I suspect the
unit is 25 to 30 years old. Unfortunately, there were no 'dates' on the
stickers to tell when the unit was last calibrated.
I was thinking of sending the 3458A's and the 732A out for calibration
simultaneously and seeing what I find when they get back.
I'll call Fluke and ask about their Cal services, the plug, and the shipping
case/battery pack issues.
Thanks everyone for very useful information.
Joe
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On
Behalf Of Charles Steinmetz
Sent: Monday, December 30, 2013 11:23 PM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Fluke 732A Questions
Joe wrote:
Also, how do you get your 732A calibrated? Do the batteries last long
enough to ship overnight to a facility?
No -- I assumed that was why you were looking for a battery connector. You
install an external battery for shipment overnight. Fluke can supply a
complete external battery with cable and plug ($375, last I knew), or you
can make your own. I believe they can also supply a shipping container,
which has a dedicated space for the Fluke external battery. (If you don't
use Fluke's container, build something very sturdy with wood and padding and
with handles that make it hard not to carry it and set it down right side
up.)
I wouldn't have anybody but Fluke calibrate a 732A. There are 3 levels of
calibration, all with data, from about $700 to about $1500 (the last is
calibration by Fluke's Primary Standards Lab).
As far as thermistor values go, the relevant question is not what is the
value in absolute terms, but rather what is the value in relation to the "as
manufactured" value, which was provided by Fluke when the unit shipped.
This had been recorded by the original owners of each of my units, and they
are all within 2 ohms of the original value today.
If you do not know the original value, then your original measurement is a
"going forward" value and it cannot tell you anything about where you are in
relation to the original manufactured value. The fact that you had to
change cal jumpers suggests that either the oven temperature has shifted
since manufacture, the reference assembly has shifted, or both.
Fluke has said various things in various places about how far the thermistor
readings can drift before you have a problem. +/- 20 ohms over the unit's
lifetime seems to be a good consensus value. If it changes fast -- say, 10
ohms or more in a month -- you have a problem.
Best regards,
Charles
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.
Joe
Reference the thermistor value and its recorded value - I asked Fluke this
question and the answer was, they did supply the individual 732A's value in
written form to the original purchaser, but unfortunately they did not
maintain a separate record.
Roy
-----Original Message-----
From: J. L. Trantham
Sent: Tuesday, December 31, 2013 1:22 PM
To: 'Discussion of precise voltage measurement'
Subject: Re: [volt-nuts] Fluke 732A Questions
Charles,
I would like to find the mating plug for J10 for several reasons, being able
to get it to calibration being just one of them. However, I was hoping it
would be good enough to make it to calibration on the internal batteries.
I seem to recall reading that the internal batteries were good for a few
hours but nothing like what the 732B would do, which sounded like the 732B
could make the trip on the internal batteries.
Where did you find the resistance of the thermistor 'as shipped'? I saw
mention of being supplied to the original owner when shipped as well and I
have had the top cover off and the battery module out to replace the
batteries and found nothing to suggest a thermistor value. I have also
lifted the top layer of insulation off the oven to move the cal-jumpers but
did not see anything that suggested a thermistor value.
My 'metrology level' standards are my HP 3458A's, calibrated by Agilent, and
Solartron (Ametek) 7081's calibrated by Ametek. I have been thinking of
getting the 732A calibrated by Fluke but I didn't know if they would still
calibrate the unit. I wonder if they would have the 'as shipped' thermistor
value on file for my specific serial number?
I, too, read about the stability of the thermistor being the most important
measurement. That was in the 'change sheets' attached to the manual on
Didier's site.
The 'cal-jumper' was at '40' when I got the unit. Per my 3458A, I could
only get it down from about +220 uV to about +100 uV with the front panel
adjustment. By moving the jumper to '20', I could only get it up to about
-12 uV below 10 V by turning the adjustment all the way in the opposite
direction. However, by connecting jumpers for both the '20' and '10', I was
able to get it at 10 V with the front panel adjustment at about center
position. I have not 'logged' any values yet but every time I go to the
shop, it is about +/- 1 or 2 uV from 10 V. I do the 'AUTO CAL' on the 3458A
each morning I go into the shop.
I measure the resistance with a Fluke 8050A (simply because it is the
closest DMM to the standard) and it is 4229 to 4230 ohms each day.
Interestingly, when I got the 732A, undisturbed Fluke Calibration stickers
were in place over each of the adjustments on the front panel, on a back
screw on the top cover, and 'half' of a sticker on the back over the power
supply module, as if the other half was lost when someone removed the
battery module. Somehow, I find that comforting, given that it now seems so
stable, making me think it is 'normal aging' that is responsible for the
values I measured rather than a problem with the oven, etc.. IIRC, the spec
is 6 ppm per year for 10 V, or 60 uV per year. I'll have to look at the
power supply module to see if I can find some date codes but I suspect the
unit is 25 to 30 years old. Unfortunately, there were no 'dates' on the
stickers to tell when the unit was last calibrated.
I was thinking of sending the 3458A's and the 732A out for calibration
simultaneously and seeing what I find when they get back.
I'll call Fluke and ask about their Cal services, the plug, and the shipping
case/battery pack issues.
Thanks everyone for very useful information.
Joe
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On
Behalf Of Charles Steinmetz
Sent: Monday, December 30, 2013 11:23 PM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Fluke 732A Questions
Joe wrote:
Also, how do you get your 732A calibrated? Do the batteries last long
enough to ship overnight to a facility?
No -- I assumed that was why you were looking for a battery connector. You
install an external battery for shipment overnight. Fluke can supply a
complete external battery with cable and plug ($375, last I knew), or you
can make your own. I believe they can also supply a shipping container,
which has a dedicated space for the Fluke external battery. (If you don't
use Fluke's container, build something very sturdy with wood and padding and
with handles that make it hard not to carry it and set it down right side
up.)
I wouldn't have anybody but Fluke calibrate a 732A. There are 3 levels of
calibration, all with data, from about $700 to about $1500 (the last is
calibration by Fluke's Primary Standards Lab).
As far as thermistor values go, the relevant question is not what is the
value in absolute terms, but rather what is the value in relation to the "as
manufactured" value, which was provided by Fluke when the unit shipped.
This had been recorded by the original owners of each of my units, and they
are all within 2 ohms of the original value today.
If you do not know the original value, then your original measurement is a
"going forward" value and it cannot tell you anything about where you are in
relation to the original manufactured value. The fact that you had to
change cal jumpers suggests that either the oven temperature has shifted
since manufacture, the reference assembly has shifted, or both.
Fluke has said various things in various places about how far the thermistor
readings can drift before you have a problem. +/- 20 ohms over the unit's
lifetime seems to be a good consensus value. If it changes fast -- say, 10
ohms or more in a month -- you have a problem.
Best regards,
Charles
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 was afraid of that.
Joe
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On
Behalf Of R.Phillips
Sent: Tuesday, December 31, 2013 7:53 AM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Fluke 732A Questions
Joe
Reference the thermistor value and its recorded value - I asked Fluke this
question and the answer was, they did supply the individual 732A's value in
written form to the original purchaser, but unfortunately they did not
maintain a separate record.
Roy
-----Original Message-----
From: J. L. Trantham
Sent: Tuesday, December 31, 2013 1:22 PM
To: 'Discussion of precise voltage measurement'
Subject: Re: [volt-nuts] Fluke 732A Questions
Charles,
I would like to find the mating plug for J10 for several reasons, being able
to get it to calibration being just one of them. However, I was hoping it
would be good enough to make it to calibration on the internal batteries.
I seem to recall reading that the internal batteries were good for a few
hours but nothing like what the 732B would do, which sounded like the 732B
could make the trip on the internal batteries.
Where did you find the resistance of the thermistor 'as shipped'? I saw
mention of being supplied to the original owner when shipped as well and I
have had the top cover off and the battery module out to replace the
batteries and found nothing to suggest a thermistor value. I have also
lifted the top layer of insulation off the oven to move the cal-jumpers but
did not see anything that suggested a thermistor value.
My 'metrology level' standards are my HP 3458A's, calibrated by Agilent, and
Solartron (Ametek) 7081's calibrated by Ametek. I have been thinking of
getting the 732A calibrated by Fluke but I didn't know if they would still
calibrate the unit. I wonder if they would have the 'as shipped' thermistor
value on file for my specific serial number?
I, too, read about the stability of the thermistor being the most important
measurement. That was in the 'change sheets' attached to the manual on
Didier's site.
The 'cal-jumper' was at '40' when I got the unit. Per my 3458A, I could
only get it down from about +220 uV to about +100 uV with the front panel
adjustment. By moving the jumper to '20', I could only get it up to about
-12 uV below 10 V by turning the adjustment all the way in the opposite
direction. However, by connecting jumpers for both the '20' and '10', I was
able to get it at 10 V with the front panel adjustment at about center
position. I have not 'logged' any values yet but every time I go to the
shop, it is about +/- 1 or 2 uV from 10 V. I do the 'AUTO CAL' on the 3458A
each morning I go into the shop.
I measure the resistance with a Fluke 8050A (simply because it is the
closest DMM to the standard) and it is 4229 to 4230 ohms each day.
Interestingly, when I got the 732A, undisturbed Fluke Calibration stickers
were in place over each of the adjustments on the front panel, on a back
screw on the top cover, and 'half' of a sticker on the back over the power
supply module, as if the other half was lost when someone removed the
battery module. Somehow, I find that comforting, given that it now seems so
stable, making me think it is 'normal aging' that is responsible for the
values I measured rather than a problem with the oven, etc.. IIRC, the spec
is 6 ppm per year for 10 V, or 60 uV per year. I'll have to look at the
power supply module to see if I can find some date codes but I suspect the
unit is 25 to 30 years old. Unfortunately, there were no 'dates' on the
stickers to tell when the unit was last calibrated.
I was thinking of sending the 3458A's and the 732A out for calibration
simultaneously and seeing what I find when they get back.
I'll call Fluke and ask about their Cal services, the plug, and the shipping
case/battery pack issues.
Thanks everyone for very useful information.
Joe
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On
Behalf Of Charles Steinmetz
Sent: Monday, December 30, 2013 11:23 PM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Fluke 732A Questions
Joe wrote:
Also, how do you get your 732A calibrated? Do the batteries last long
enough to ship overnight to a facility?
No -- I assumed that was why you were looking for a battery connector. You
install an external battery for shipment overnight. Fluke can supply a
complete external battery with cable and plug ($375, last I knew), or you
can make your own. I believe they can also supply a shipping container,
which has a dedicated space for the Fluke external battery. (If you don't
use Fluke's container, build something very sturdy with wood and padding and
with handles that make it hard not to carry it and set it down right side
up.)
I wouldn't have anybody but Fluke calibrate a 732A. There are 3 levels of
calibration, all with data, from about $700 to about $1500 (the last is
calibration by Fluke's Primary Standards Lab).
As far as thermistor values go, the relevant question is not what is the
value in absolute terms, but rather what is the value in relation to the "as
manufactured" value, which was provided by Fluke when the unit shipped.
This had been recorded by the original owners of each of my units, and they
are all within 2 ohms of the original value today.
If you do not know the original value, then your original measurement is a
"going forward" value and it cannot tell you anything about where you are in
relation to the original manufactured value. The fact that you had to
change cal jumpers suggests that either the oven temperature has shifted
since manufacture, the reference assembly has shifted, or both.
Fluke has said various things in various places about how far the thermistor
readings can drift before you have a problem. +/- 20 ohms over the unit's
lifetime seems to be a good consensus value. If it changes fast -- say, 10
ohms or more in a month -- you have a problem.
Best regards,
Charles
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