Reference Calibration Options - Solartron 7081 and Fluke 731B and 335A
I have explored the options for calibration of my 'reference' devices.
The Solartron 7081 calibration is available in Oak Ridge, TN, at Advanced Measurement Technology http://www.ametek-online.com/ for $800.00. They are the US branch of the company that owns Solartron, if I understanad correctly. I have emailed with a number of questions regarding the specific details of the calibration and documents supplied but have not received a reply so far. I suspect the Service Coordinator I emailed is busy chasing down the answers for my many questions.
For the 731B, Fluke offers a Performance Test for $229, Calibration, Traceable, W/O Data for $245, Calibration, Z540 Traceable, W/O Data for $259 and Calibration, Z540 Traceable, W/ Data for $333. There is no repair service available.
For the 335A, there is no Performance Test option and there, also, is no repair service available. However, for the remainder, it is $473, $505, and $662 respectively.
My thought is to get the 7081 calibrated and one of the 731B's. The 'white face' 731B is the later unit with the modifications hand written in the manual downloaded from the Fluke website already in place. The 'black face' unit is older and does not have these modifications installed. I'm thinking the 'white face' unit would be the best to get calibrated.
Once these are done, I can then do the 'calibration' of the 335A and the other 731B myself.
Any thoughts about this plan, which calibration to choose, or other options that might be available? Also, any thoughts about the potential to need 'repair' of these Fluke units when sent for calibration?
Thanks in advance.
Joe
Hi Joe,
Whichever standards you choose to have calibrated, IMHO it would be
important to choose the calibration option With Data. Otherwise an
instrument's parameter might be in tolerance but very close to its spec
limit - and you would have no way of knowing that without the data.
I agree that the 335A is "odd man out" as far as candidates for the
selection. So it looks like you've narrowed it down to either the 7081 or
731B or both.
If you get a full cal on the 7081, you'll have many data points of
reference, not just 10Vdc. But the calibration is expensive, needless to
say!
-Greg
----- Original Message -----
From: "J. L. Trantham" jltran@att.net
To: volt-nuts@febo.com
Sent: Wednesday, September 07, 2011 8:58 PM
Subject: [volt-nuts] Reference Calibration Options - Solartron 7081 andFluke
731B and 335A
I have explored the options for calibration of my 'reference' devices.
The Solartron 7081 calibration is available in Oak Ridge, TN, at Advanced
Measurement Technology http://www.ametek-online.com/ for $800.00. They are
the US branch of the company that owns Solartron, if I understanad
correctly. I have emailed with a number of questions regarding the specific
details of the calibration and documents supplied but have not received a
reply so far. I suspect the Service Coordinator I emailed is busy chasing
down the answers for my many questions.
For the 731B, Fluke offers a Performance Test for $229, Calibration,
Traceable, W/O Data for $245, Calibration, Z540 Traceable, W/O Data for $259
and Calibration, Z540 Traceable, W/ Data for $333. There is no repair
service available.
For the 335A, there is no Performance Test option and there, also, is no
repair service available. However, for the remainder, it is $473, $505, and
$662 respectively.
My thought is to get the 7081 calibrated and one of the 731B's. The 'white
face' 731B is the later unit with the modifications hand written in the
manual downloaded from the Fluke website already in place. The 'black face'
unit is older and does not have these modifications installed. I'm thinking
the 'white face' unit would be the best to get calibrated.
Once these are done, I can then do the 'calibration' of the 335A and the
other 731B myself.
Any thoughts about this plan, which calibration to choose, or other options
that might be available? Also, any thoughts about the potential to need
'repair' of these Fluke units when sent for calibration?
Thanks in advance.
Joe
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Hi Joe,
Another thing to ask AMTEK is whether or not their 7081 calibration always
includes adjustment? Or do they only adjust if a parameter reaches a
guardband limit or spec limit?
Obviously for your purposes it would be nice if they adjusted the box back
to nominal. But that's not a typical service for most T&M calibrations.
The neat thing about the "golden" calibration (Loveland Standards Lab Cal)
for Agilent's 3458A is that it always includes adjustment of the box back
to nominal. But that turns out to be more feasible in the case of the 3458A
because there are only 3 adjustments for the total DCV, DCA and ohms
functions: CAL 0, CAL 10 and CAL 10k. (Note: This *always adjust" policy
only applies to the "golden" 3458A cal, not for example the "silver" cal.)
Let us know what you find out from AMTEK regarding their 7081 cal.
Thanks,
Greg
----- Original Message -----
From: "J. L. Trantham" jltran@att.net
To: volt-nuts@febo.com
Sent: Wednesday, September 07, 2011 8:58 PM
Subject: [volt-nuts] Reference Calibration Options - Solartron 7081 andFluke
731B and 335A
I have explored the options for calibration of my 'reference' devices.
The Solartron 7081 calibration is available in Oak Ridge, TN, at Advanced
Measurement Technology http://www.ametek-online.com/ for $800.00. They are
the US branch of the company that owns Solartron, if I understanad
correctly. I have emailed with a number of questions regarding the specific
details of the calibration and documents supplied but have not received a
reply so far. I suspect the Service Coordinator I emailed is busy chasing
down the answers for my many questions.
For the 731B, Fluke offers a Performance Test for $229, Calibration,
Traceable, W/O Data for $245, Calibration, Z540 Traceable, W/O Data for $259
and Calibration, Z540 Traceable, W/ Data for $333. There is no repair
service available.
For the 335A, there is no Performance Test option and there, also, is no
repair service available. However, for the remainder, it is $473, $505, and
$662 respectively.
My thought is to get the 7081 calibrated and one of the 731B's. The 'white
face' 731B is the later unit with the modifications hand written in the
manual downloaded from the Fluke website already in place. The 'black face'
unit is older and does not have these modifications installed. I'm thinking
the 'white face' unit would be the best to get calibrated.
Once these are done, I can then do the 'calibration' of the 335A and the
other 731B myself.
Any thoughts about this plan, which calibration to choose, or other options
that might be available? Also, any thoughts about the potential to need
'repair' of these Fluke units when sent for calibration?
Thanks in advance.
Joe
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and follow the instructions there.
I have still not gotten the reply from AMTEK. The questions I asked were
for the details of the calibration (though I did not ask specifically about
adjustment, just assumed that it was part of the calibration) and what
services (primarily repair) and products (manuals, test cables, etc.) they
had for the 7081. As far as the 731B's and 335A go, I think I will wait on
the 7081 to get back (assuming they are not just blowing me off) then
measure the 731B's since Fluke offers no repair service. If I read the
manual correctly, I think I will have a chance of bringing them to spec
myself.
The 335A seems to have another issue that I will explore over the weekend.
There is about 5 mV of ripple on the output. I think I am going to need to
delve into the beast for a 'rebuild' with probable replacement of the power
supply capacitors and perhaps others. Since the cost of this calibration is
the higher of the Fluke costs and the 'rep' on the beast per the list is
'suboptimal', I think I will keep this 'inhouse' and rebuild and recalibrate
myself, after I get the 7081 issue resolved.
Pending all the above, I may then send one of the 731B's in for an
'official' Fluke calibration to act as a verification of the 7081.
I would surely like to add something like the 3458A to the collection but
the price seems prohibitive. For my needs, if I can get the 7081 cal'd, it
will more than meet my needs.
Joe
----- Original Message -----
From: "gbusg" gbusg@comcast.net
To: "Discussion of precise voltage measurement" volt-nuts@febo.com
Sent: Friday, September 09, 2011 8:09 PM
Subject: Re: [volt-nuts] Reference Calibration Options - Solartron
7081andFluke 731B and 335A
Hi Joe,
Another thing to ask AMTEK is whether or not their 7081 calibration always
includes adjustment? Or do they only adjust if a parameter reaches a
guardband limit or spec limit?
Obviously for your purposes it would be nice if they adjusted the box back
to nominal. But that's not a typical service for most T&M calibrations.
The neat thing about the "golden" calibration (Loveland Standards Lab Cal)
for Agilent's 3458A is that it always includes adjustment of the box
back
to nominal. But that turns out to be more feasible in the case of the
3458A
because there are only 3 adjustments for the total DCV, DCA and ohms
functions: CAL 0, CAL 10 and CAL 10k. (Note: This *always adjust" policy
only applies to the "golden" 3458A cal, not for example the "silver" cal.)
Let us know what you find out from AMTEK regarding their 7081 cal.
Thanks,
Greg
Joe wrote:
Pending all the above, I may then send one of the 731B's in for an
'official' Fluke calibration to act as a verification of the 7081.
As several of us have noted, the 731s should be the most stable of
the bunch, because that is precisely what they were designed for. It
only makes sense to have a traceable calibration on your most stable
standard -- that gives you the best chance of accurately riding herd
on the others.
Best regards,
Charles
Charles,
What are the 1year 10Vdc specs for the 731B vs 7081?
Thanks,
Greg
----- Original Message -----
From: "Charles P. Steinmetz" charles_steinmetz@lavabit.com
To: "Discussion of precise voltage measurement" volt-nuts@febo.com
Sent: Friday, September 09, 2011 9:09 PM
Subject: Re: [volt-nuts] Reference Calibration Options - Solartron
7081andFluke 731B and 335A
Joe wrote:
Pending all the above, I may then send one of the 731B's in for an
'official' Fluke calibration to act as a verification of the 7081.
As several of us have noted, the 731s should be the most stable of
the bunch, because that is precisely what they were designed for. It
only makes sense to have a traceable calibration on your most stable
standard -- that gives you the best chance of accurately riding herd
on the others.
Best regards,
Charles
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Greg wrote:
What are the 1year 10Vdc specs for the 731B vs 7081?
Fluke specifies all outputs of the 731B at +/- 30 ppm absolute
accuracy at 1 year, at 23C +/- 1 degree after a 30 minute warmup (+/-
15 ppm/90 days, +/- 10 ppm/30 days). The 10 V outputs of the three
that I've had were better by more than an order of magnitude --
around 2 ppm/year (but note that mine were powered 24/7/365). The 1
V and 1.018 V outputs are significantly less stable than the 10 V
output, but well within spec.
The 10 V output of the 732A (which I use now) is specified at +/- 6
ppm/year (+/- 3 ppm/6 months, +/- 1.5 ppm/90 days, +/- 0.5 ppm/30
days), for temperatures between 18C and 28C. The ones I have do
much, much better. There is an interesting 1999 IEEE paper by
Vujevic and Ilic, "Stability of Some DC Reference Standards," which
discusses he 732A and notes that it is stable to about 0.1 ppm/year,
which is consistent with my observations.
Given a calibration history, one can plot the expected absolute
voltage as a function of time and get even closer.
Meters are specified somewhat differently, since there are several
distinct error mechanisms. My understanding is that the 7081 is
specified as more stable than an HP3458A (which has a specified total
error at 10 V of a bit more than 10 ppm/year, including calibration
traceability error), but that within the cal lab community they are
not considered to be anywhere near as stable as the HP.
Best regards,
Charles
Yeah, I'm using a 732A. It's a nice box, as you know.
I'm also using a pair of Koep PN-VTS3005 10Vdc standards. Over an 8 year
period one Koep drifted +0.104 ppm/year; and the other
Koep drifted +0.701 ppm/year. However the Koep's short-term noise and tempco
are notably worse than the Fluke 732A, so I like the 732A the best. (Wish I
had a 732B, but those are pricey indeed!)
I also used to have a 731B, but my particular 731B was drifting something
like 10ppm/year - that's still well within its 30ppm/year spec, but it
wasn't to my liking, so I got rid of it.
The Solartron 7081 is spec'd +/- 4.3ppm at 10Vdc/year (2nd year), so based
on published specs the 7081 uncertainty at 10Vdc is almost 7x better than
the 731B (spec'd 30ppm/year).
Not having personal experience with the 7081, I can't offer anything
anecdotal about it. ...So I must rely on what actual owners (of the 7081)
have experienced. (Have you read anything from any actual users claiming
that their 7081 did not meet the 4.3ppm/year spec at 10Vdc? ...Would like
to read more about that if you have any web links to comments about it?
Thanks,
Greg
----- Original Message -----
From: "Charles P. Steinmetz" charles_steinmetz@lavabit.com
To: "Discussion of precise voltage measurement" volt-nuts@febo.com
Sent: Friday, September 09, 2011 11:22 PM
Subject: Re: [volt-nuts] Reference Calibration Options - Solartron
7081andFluke 731B and 335A
Fluke specifies all outputs of the 731B at +/- 30 ppm absolute
accuracy at 1 year, at 23C +/- 1 degree after a 30 minute warmup (+/-
15 ppm/90 days, +/- 10 ppm/30 days). The 10 V outputs of the three
that I've had were better by more than an order of magnitude --
around 2 ppm/year (but note that mine were powered 24/7/365). The 1
V and 1.018 V outputs are significantly less stable than the 10 V
output, but well within spec.
The 10 V output of the 732A (which I use now) is specified at +/- 6
ppm/year (+/- 3 ppm/6 months, +/- 1.5 ppm/90 days, +/- 0.5 ppm/30
days), for temperatures between 18C and 28C. The ones I have do
much, much better. There is an interesting 1999 IEEE paper by
Vujevic and Ilic, "Stability of Some DC Reference Standards," which
discusses he 732A and notes that it is stable to about 0.1 ppm/year,
which is consistent with my observations.
Given a calibration history, one can plot the expected absolute
voltage as a function of time and get even closer.
Meters are specified somewhat differently, since there are several
distinct error mechanisms. My understanding is that the 7081 is
specified as more stable than an HP3458A (which has a specified total
error at 10 V of a bit more than 10 ppm/year, including calibration
traceability error), but that within the cal lab community they are
not considered to be anywhere near as stable as the HP.
Best regards,
Charles
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How do you know the standards drift and not the meters ? In worst case they could drift the same amount in the same direction.
A week ago I have my 731A and 7061 calibrated against a standard cell. The fisrt days the long and short time drift was considrable. But the 731A is now powered 24/7. Yesterday i turned on the 7061 again and it showed 1.000,006,2 V after three hours it was 1.000,000,1 V and stayed there, so keeping it powered on seems to work better.
My home made standard with out of the box cheap reference zeners, four TL431 parallel. I have last week adjusted to 1.000,000 V on the keithley 2000.
After a week it was 1.000,046 but I adjusted it to 1 V again. But the reference in that has only about 150 hours burn in time total. The Short time drift is now allmost gone. It flips + 1 uV now and then, but it could be it is adjusted to 1.000,000,8 or so.
The second one, made with an othere reference but also a standard low cost reference, a ADR421 mde to be transportable and can be powerd from anything between 6 and 12 V was adjusted to 2.500,01 on the keithley ( just stopped when the last digit flipped to 1 so I know it is as close as known as posible. ) it has not been on power this week. I put it on again yesterday and left it on for about 6 hours. It started at 2.500,01 and stayed there all the time. Weird, is the , also brand new, ADR421 so much better ?
Within a week or so i am going to order parts for the 1-2000MHz signal generator i m building, and then i want to order some better voltage references. The LM399 is not vailable. What would be the best choise ? ( I will order from Farnell) i like a reference with low tempco, so with build in heather because my lab is on the addict and temp changes can be big. From 16 to 35 dergees as extremes.
Fred PA4TIM
Op 10 sep. 2011 om 08:03 heeft "gbusg" gbusg@comcast.net het volgende geschreven:
Yeah, I'm using a 732A. It's a nice box, as you know.
I'm also using a pair of Koep PN-VTS3005 10Vdc standards. Over an 8 year
period one Koep drifted +0.104 ppm/year; and the other
Koep drifted +0.701 ppm/year. However the Koep's short-term noise and tempco
are notably worse than the Fluke 732A, so I like the 732A the best. (Wish I
had a 732B, but those are pricey indeed!)
I also used to have a 731B, but my particular 731B was drifting something
like 10ppm/year - that's still well within its 30ppm/year spec, but it
wasn't to my liking, so I got rid of it.
The Solartron 7081 is spec'd +/- 4.3ppm at 10Vdc/year (2nd year), so based
on published specs the 7081 uncertainty at 10Vdc is almost 7x better than
the 731B (spec'd 30ppm/year).
Not having personal experience with the 7081, I can't offer anything
anecdotal about it. ...So I must rely on what actual owners (of the 7081)
have experienced. (Have you read anything from any actual users claiming
that their 7081 did not meet the 4.3ppm/year spec at 10Vdc? ...Would like
to read more about that if you have any web links to comments about it?
Thanks,
Greg
----- Original Message -----
From: "Charles P. Steinmetz" charles_steinmetz@lavabit.com
To: "Discussion of precise voltage measurement" volt-nuts@febo.com
Sent: Friday, September 09, 2011 11:22 PM
Subject: Re: [volt-nuts] Reference Calibration Options - Solartron
7081andFluke 731B and 335A
Fluke specifies all outputs of the 731B at +/- 30 ppm absolute
accuracy at 1 year, at 23C +/- 1 degree after a 30 minute warmup (+/-
15 ppm/90 days, +/- 10 ppm/30 days). The 10 V outputs of the three
that I've had were better by more than an order of magnitude --
around 2 ppm/year (but note that mine were powered 24/7/365). The 1
V and 1.018 V outputs are significantly less stable than the 10 V
output, but well within spec.
The 10 V output of the 732A (which I use now) is specified at +/- 6
ppm/year (+/- 3 ppm/6 months, +/- 1.5 ppm/90 days, +/- 0.5 ppm/30
days), for temperatures between 18C and 28C. The ones I have do
much, much better. There is an interesting 1999 IEEE paper by
Vujevic and Ilic, "Stability of Some DC Reference Standards," which
discusses he 732A and notes that it is stable to about 0.1 ppm/year,
which is consistent with my observations.
Given a calibration history, one can plot the expected absolute
voltage as a function of time and get even closer.
Meters are specified somewhat differently, since there are several
distinct error mechanisms. My understanding is that the 7081 is
specified as more stable than an HP3458A (which has a specified total
error at 10 V of a bit more than 10 ppm/year, including calibration
traceability error), but that within the cal lab community they are
not considered to be anywhere near as stable as the HP.
Best regards,
Charles
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Greg wrote:
(Wish I had a 732B, but those are pricey indeed!)
A number of cal types I know think the performance of the 732A is
actually better than the 732B. I have not played with the B myself,
so I cannot comment from personal experience.
The Solartron 7081 is spec'd +/- 4.3ppm at 10Vdc/year (2nd year), so based
on published specs the 7081 uncertainty at 10Vdc is almost 7x better than
the 731B (spec'd 30ppm/year).
Perhaps, but the actual expected stability of a properly operating
731B (particularly one that has been operating 24/7 for several years
or more) is significantly better than the specified performance of a
7081 (or 3458A), and in addition its drift can be characterized
reasonably accurately and subtracted (not so much with meters, with
their several different error mechanisms).
Not having personal experience with the 7081, I can't offer anything
anecdotal about it. ...So I must rely on what actual owners (of the 7081)
have experienced. (Have you read anything from any actual users claiming
that their 7081 did not meet the 4.3ppm/year spec at 10Vdc?
I designed some process control systems that were used by a number of
clients, which, due to systems integration requirements, used
off-the-shelf DMMs to monitor DC process variables (6 to 24 per
system). I specified 3458As, and several clients used 7081s
instead. Those clients all had problems that were traced to the
accuracy of the 7081s, and changing to 3458As cured the problems. As
far as I know, no time was spent characterizing the 7081s that were
pulled, but they were all brand new and there was no reason to
believe they were not operating nominally.
Best regards,
Charles