What's All This Low Thermal EMF Test Lead Stuff?
I'm a self described volt-nut-near-beer. I don't own a 732A/B, or an
HP3458. I do own HP3456 DMMs that are at the top of my instrumentation
pecking order. I have all the necessary gear to calibrate these DMMs
according to ancient HP documentation. At the top of my cal. chain is the
731B, called out in HP3456 original documentation. This hierarchy places
me in the near-beer, or junior member status of the group. I look forward
to being educated, and/or corrected on my understanding of the use of test
leads with precision instrumentation.
I don't find much ancient HP documentation on test leads. The only
recommendations in the era of the 3456 back to the 1960's is to use as
thick a solid lead of pure copper wire as you can find, and insert the wire
into the drill hole on the banana terminal. If the copper is pure, and has
been properly cleaned, the thermal emf's on both identical length leads
should all be balanced, and cancel out. In any case, pure copper-copper
connections generate the lowest thermal emf. I will agree that manhandling
16 gauge solid wire can be very inconvenient.
The path I have taken recently is to order Nakamichi gold over copper
stereo banana plugs for my connections ( I deal in low voltage work
exclusively), as well as gold plated spade lugs to go under the banana
screw-downs. ( My budget ruled out gold over beryllium copper Pomona brand
spades. ) I will then experiment between the two connector types. As for
connections, it seems to me the best course is just to screw down the
banana plugs, or in the case of the spades, just crimp. I'll wing it on the
crimping, and see if simple tools can perform adequately. I would avoid
solder, since how can one form identical topological spots of solder on
every connection, deposited at the exact same place on each connection, and
ensure the exact same weight of solder, to the microgram, on each
connection. Since my modus operandi is to aim for balanced emfs, I think
solder is out. Of course, if one wishes to risk one's health, and that of
the family, one can track down a source of cadmium, and mix up a lot of low
thermal emf solder (cadmium solder is banned in the US, and EU)...not for
me.
Don't worry, I won't be using tin plated wire, I managed to pick up a spool
of silver plated 16 gauge wire for my investigations. Am I on some other
planet for choosing the balanced thermal emf approach for precision test
lead applications, as opposed to going to great lengths to eliminate every
trace of emf?
Please forgive me if these emf discussions have been between engineers
working outdoors in the oil fields of North Dakota, or out on a North Sea
drilling platform. In that case, go for all the super low emf techniques
you can lay your hands on.
Good Luck,
Stan
generally I think, and at least for your gear, if you use copper plugs of some type and even solder the wires, thats perfectly fine.
also for a 3458a, and after proper temp stabilization after connecting the cables (5min) which you always need, these are fine, have not measrured any difference to crimped cables. also the type of cable plating (tin/silver..) does not make much difference.
there were many discussions over time, but all the cadmium solder and non plated copper type debates are not making much sense down to the 3458a level.
I have not done comparison tests with nanovolt meters, as mine have fixed cables, so no option to change them without destroying them, but note that e.g. the 182 nanovolt meter has a mil type plug (no special contacts). sources of error are also things like where to connect the guard to, these often make a much bigger difference (I have seen these many times, causing voltage differences of several uV depending where in the setup you connected the guard, while otherwise the measurement was perfectly stable), and I bet while people put a lot of effort into the emf discussion, the guard issue is more often causing errors in measurements in real life. and thats just one example of additional causes of errors.
cheers
Gesendet: Dienstag, 19. August 2014 um 06:07 Uhr
Von: "Stan Katz" stan.katz.hk@gmail.com
An: "Discussion of precise voltage measurement" volt-nuts@febo.com
Betreff: [volt-nuts] What's All This Low Thermal EMF Test Lead Stuff?
I'm a self described volt-nut-near-beer. I don't own a 732A/B, or an
HP3458. I do own HP3456 DMMs that are at the top of my instrumentation
pecking order. I have all the necessary gear to calibrate these DMMs
according to ancient HP documentation. At the top of my cal. chain is the
731B, called out in HP3456 original documentation. This hierarchy places
me in the near-beer, or junior member status of the group. I look forward
to being educated, and/or corrected on my understanding of the use of test
leads with precision instrumentation.
I don't find much ancient HP documentation on test leads. The only
recommendations in the era of the 3456 back to the 1960's is to use as
thick a solid lead of pure copper wire as you can find, and insert the wire
into the drill hole on the banana terminal. If the copper is pure, and has
been properly cleaned, the thermal emf's on both identical length leads
should all be balanced, and cancel out. In any case, pure copper-copper
connections generate the lowest thermal emf. I will agree that manhandling
16 gauge solid wire can be very inconvenient.
The path I have taken recently is to order Nakamichi gold over copper
stereo banana plugs for my connections ( I deal in low voltage work
exclusively), as well as gold plated spade lugs to go under the banana
screw-downs. ( My budget ruled out gold over beryllium copper Pomona brand
spades. ) I will then experiment between the two connector types. As for
connections, it seems to me the best course is just to screw down the
banana plugs, or in the case of the spades, just crimp. I'll wing it on the
crimping, and see if simple tools can perform adequately. I would avoid
solder, since how can one form identical topological spots of solder on
every connection, deposited at the exact same place on each connection, and
ensure the exact same weight of solder, to the microgram, on each
connection. Since my modus operandi is to aim for balanced emfs, I think
solder is out. Of course, if one wishes to risk one's health, and that of
the family, one can track down a source of cadmium, and mix up a lot of low
thermal emf solder (cadmium solder is banned in the US, and EU)...not for
me.
Don't worry, I won't be using tin plated wire, I managed to pick up a spool
of silver plated 16 gauge wire for my investigations. Am I on some other
planet for choosing the balanced thermal emf approach for precision test
lead applications, as opposed to going to great lengths to eliminate every
trace of emf?
Please forgive me if these emf discussions have been between engineers
working outdoors in the oil fields of North Dakota, or out on a North Sea
drilling platform. In that case, go for all the super low emf techniques
you can lay your hands on.
Good Luck,
Stan
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.
Stan,
I recently picked up some of these ...
http://www.douglasconnection.com/Furez-TSTWP30NP-Bare-Copper-Banana-Plug-Connectors-Pair-FZTSTWP30NP.htm
They are a little pricey and are made for 12ga wire. I think they are OK
for semi-permanent use. A lot of use will probably scratch the soft metal.
I plan on trying them with my Keithley 181 plugged into a low thermal
scanner.
The original Keithley cable will be difficult to terminate. I may have to
go with crimped spade lugs.
Also, I am all for joining a beer nuts group.
Todd
On Tue, Aug 19, 2014 at 2:07 AM, Stan Katz stan.katz.hk@gmail.com wrote:
I'm a self described volt-nut-near-beer. I don't own a 732A/B, or an
HP3458. I do own HP3456 DMMs that are at the top of my instrumentation
pecking order. I have all the necessary gear to calibrate these DMMs
according to ancient HP documentation. At the top of my cal. chain is the
731B, called out in HP3456 original documentation. This hierarchy places
me in the near-beer, or junior member status of the group. I look forward
to being educated, and/or corrected on my understanding of the use of test
leads with precision instrumentation.
I don't find much ancient HP documentation on test leads. The only
recommendations in the era of the 3456 back to the 1960's is to use as
thick a solid lead of pure copper wire as you can find, and insert the wire
into the drill hole on the banana terminal. If the copper is pure, and has
been properly cleaned, the thermal emf's on both identical length leads
should all be balanced, and cancel out. In any case, pure copper-copper
connections generate the lowest thermal emf. I will agree that manhandling
16 gauge solid wire can be very inconvenient.
The path I have taken recently is to order Nakamichi gold over copper
stereo banana plugs for my connections ( I deal in low voltage work
exclusively), as well as gold plated spade lugs to go under the banana
screw-downs. ( My budget ruled out gold over beryllium copper Pomona brand
spades. ) I will then experiment between the two connector types. As for
connections, it seems to me the best course is just to screw down the
banana plugs, or in the case of the spades, just crimp. I'll wing it on the
crimping, and see if simple tools can perform adequately. I would avoid
solder, since how can one form identical topological spots of solder on
every connection, deposited at the exact same place on each connection, and
ensure the exact same weight of solder, to the microgram, on each
connection. Since my modus operandi is to aim for balanced emfs, I think
solder is out. Of course, if one wishes to risk one's health, and that of
the family, one can track down a source of cadmium, and mix up a lot of low
thermal emf solder (cadmium solder is banned in the US, and EU)...not for
me.
Don't worry, I won't be using tin plated wire, I managed to pick up a spool
of silver plated 16 gauge wire for my investigations. Am I on some other
planet for choosing the balanced thermal emf approach for precision test
lead applications, as opposed to going to great lengths to eliminate every
trace of emf?
Please forgive me if these emf discussions have been between engineers
working outdoors in the oil fields of North Dakota, or out on a North Sea
drilling platform. In that case, go for all the super low emf techniques
you can lay your hands on.
Good Luck,
Stan
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.
You are on the money that guarding/shielding are sadly neglected as
subjects, in their own right. Posts in this group consist primarily of
reports of guard leakage in member instruments, and repair details.
Discussion of proper lash ups of cal. instruments to home built devices, or
even work prototypes, would be very welcome by me. I have read Analog
Devices AN-347, but a tutorial with problems that the student must complete
the lash ups for, would give me a better idea if I've grasped the subject
matter. There are two text books mentioned at the end of AN-347, one by
Morrison, the other by Ott. Any suggestion as to which to buy? The latest
texts by these authors are pricey, so that's why I'd like to pick just one.
On Tue, Aug 19, 2014 at 3:37 AM, acbern@gmx.de wrote:
generally I think, and at least for your gear, if you use copper plugs of
some type and even solder the wires, thats perfectly fine.
also for a 3458a, and after proper temp stabilization after connecting the
cables (5min) which you always need, these are fine, have not measrured any
difference to crimped cables. also the type of cable plating (tin/silver..)
does not make much difference.
there were many discussions over time, but all the cadmium solder and non
plated copper type debates are not making much sense down to the 3458a
level.
I have not done comparison tests with nanovolt meters, as mine have fixed
cables, so no option to change them without destroying them, but note that
e.g. the 182 nanovolt meter has a mil type plug (no special contacts).
sources of error are also things like where to connect the guard to, these
often make a much bigger difference (I have seen these many times, causing
voltage differences of several uV depending where in the setup you
connected the guard, while otherwise the measurement was perfectly stable),
and I bet while people put a lot of effort into the emf discussion, the
guard issue is more often causing errors in measurements in real life. and
thats just one example of additional causes of errors.
cheers
Gesendet: Dienstag, 19. August 2014 um 06:07 Uhr
Von: "Stan Katz" stan.katz.hk@gmail.com
An: "Discussion of precise voltage measurement" volt-nuts@febo.com
Betreff: [volt-nuts] What's All This Low Thermal EMF Test Lead Stuff?
I'm a self described volt-nut-near-beer. I don't own a 732A/B, or an
HP3458. I do own HP3456 DMMs that are at the top of my instrumentation
pecking order. I have all the necessary gear to calibrate these DMMs
according to ancient HP documentation. At the top of my cal. chain is the
731B, called out in HP3456 original documentation. This hierarchy places
me in the near-beer, or junior member status of the group. I look forward
to being educated, and/or corrected on my understanding of the use of
test
leads with precision instrumentation.
I don't find much ancient HP documentation on test leads. The only
recommendations in the era of the 3456 back to the 1960's is to use as
thick a solid lead of pure copper wire as you can find, and insert the
wire
into the drill hole on the banana terminal. If the copper is pure, and
has
been properly cleaned, the thermal emf's on both identical length leads
should all be balanced, and cancel out. In any case, pure copper-copper
connections generate the lowest thermal emf. I will agree that
manhandling
16 gauge solid wire can be very inconvenient.
The path I have taken recently is to order Nakamichi gold over copper
stereo banana plugs for my connections ( I deal in low voltage work
exclusively), as well as gold plated spade lugs to go under the banana
screw-downs. ( My budget ruled out gold over beryllium copper Pomona
brand
spades. ) I will then experiment between the two connector types. As for
connections, it seems to me the best course is just to screw down the
banana plugs, or in the case of the spades, just crimp. I'll wing it on
the
crimping, and see if simple tools can perform adequately. I would avoid
solder, since how can one form identical topological spots of solder on
every connection, deposited at the exact same place on each connection,
and
ensure the exact same weight of solder, to the microgram, on each
connection. Since my modus operandi is to aim for balanced emfs, I think
solder is out. Of course, if one wishes to risk one's health, and that of
the family, one can track down a source of cadmium, and mix up a lot of
low
thermal emf solder (cadmium solder is banned in the US, and EU)...not for
me.
Don't worry, I won't be using tin plated wire, I managed to pick up a
spool
of silver plated 16 gauge wire for my investigations. Am I on some other
planet for choosing the balanced thermal emf approach for precision test
lead applications, as opposed to going to great lengths to eliminate
every
trace of emf?
Please forgive me if these emf discussions have been between engineers
working outdoors in the oil fields of North Dakota, or out on a North Sea
drilling platform. In that case, go for all the super low emf techniques
you can lay your hands on.
Good Luck,
Stan
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
https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
Stan,
I have seen this Fluke book mentioned occasionally. I am not sure if has
the tutorials that you seek. It is advertised as specific to dc/ lf ac.
http://www.amazon.com/Calibration-Philosophy-Practice-Fluke-Corporation/dp/0963865005
Todd
On Tue, Aug 19, 2014 at 7:35 PM, Stan Katz stan.katz.hk@gmail.com wrote:
You are on the money that guarding/shielding are sadly neglected as
subjects, in their own right. Posts in this group consist primarily of
reports of guard leakage in member instruments, and repair details.
Discussion of proper lash ups of cal. instruments to home built devices, or
even work prototypes, would be very welcome by me. I have read Analog
Devices AN-347, but a tutorial with problems that the student must complete
the lash ups for, would give me a better idea if I've grasped the subject
matter. There are two text books mentioned at the end of AN-347, one by
Morrison, the other by Ott. Any suggestion as to which to buy? The latest
texts by these authors are pricey, so that's why I'd like to pick just one.
If you reserve those pure copper bananas strictly for infrequent cal. of
something like an HP3458, or other transfer standards in your lab, they
may be good for some years.
I envision the "beer nuts" to be a rather relaxed group of individuals,
who are perfectly satisfied to know the alcohol content of their favorite
brew to no better than +/- 60ppm ;-)
Why +/- 60ppm? A selfish reason. I plan on bringing home a beer-nut-NIST
volt for my Fluke 731B using one of these standards
http://www.ebay.com/itm/10-VOLT-DC-Precision-Voltage-Reference-Standard-Nulled-to-Fluke-732A-732B-/261499015291?pt=LH_DefaultDomain_0&hash=item3ce28e507b
They're only good to 6ppm according to the seller. Rule of thumb is primary
must be ten times the accuracy of secondary, that leaves me with an
uncertainty of +/-60ppm....does seem a bit much....oh well, if necessary,
I'm willing to be the only beer-nuts member.
On Tue, Aug 19, 2014 at 4:12 PM, Todd Micallef tmicallef@gmail.com wrote:
Stan,
I recently picked up some of these ...
They are a little pricey and are made for 12ga wire. I think they are OK
for semi-permanent use. A lot of use will probably scratch the soft metal.
I plan on trying them with my Keithley 181 plugged into a low thermal
scanner.
The original Keithley cable will be difficult to terminate. I may have to
go with crimped spade lugs.
Also, I am all for joining a beer nuts group.
Todd
On Tue, Aug 19, 2014 at 2:07 AM, Stan Katz stan.katz.hk@gmail.com wrote:
I'm a self described volt-nut-near-beer. I don't own a 732A/B, or an
HP3458. I do own HP3456 DMMs that are at the top of my instrumentation
pecking order. I have all the necessary gear to calibrate these DMMs
according to ancient HP documentation. At the top of my cal. chain is the
731B, called out in HP3456 original documentation. This hierarchy places
me in the near-beer, or junior member status of the group. I look forward
to being educated, and/or corrected on my understanding of the use of
test
leads with precision instrumentation.
I don't find much ancient HP documentation on test leads. The only
recommendations in the era of the 3456 back to the 1960's is to use as
thick a solid lead of pure copper wire as you can find, and insert the
wire
into the drill hole on the banana terminal. If the copper is pure, and
has
been properly cleaned, the thermal emf's on both identical length leads
should all be balanced, and cancel out. In any case, pure copper-copper
connections generate the lowest thermal emf. I will agree that
manhandling
16 gauge solid wire can be very inconvenient.
The path I have taken recently is to order Nakamichi gold over copper
stereo banana plugs for my connections ( I deal in low voltage work
exclusively), as well as gold plated spade lugs to go under the banana
screw-downs. ( My budget ruled out gold over beryllium copper Pomona
brand
spades. ) I will then experiment between the two connector types. As for
connections, it seems to me the best course is just to screw down the
banana plugs, or in the case of the spades, just crimp. I'll wing it on
the
crimping, and see if simple tools can perform adequately. I would avoid
solder, since how can one form identical topological spots of solder on
every connection, deposited at the exact same place on each connection,
and
ensure the exact same weight of solder, to the microgram, on each
connection. Since my modus operandi is to aim for balanced emfs, I think
solder is out. Of course, if one wishes to risk one's health, and that of
the family, one can track down a source of cadmium, and mix up a lot of
low
thermal emf solder (cadmium solder is banned in the US, and EU)...not for
me.
Don't worry, I won't be using tin plated wire, I managed to pick up a
spool
of silver plated 16 gauge wire for my investigations. Am I on some other
planet for choosing the balanced thermal emf approach for precision test
lead applications, as opposed to going to great lengths to eliminate
every
trace of emf?
Please forgive me if these emf discussions have been between engineers
working outdoors in the oil fields of North Dakota, or out on a North Sea
drilling platform. In that case, go for all the super low emf techniques
you can lay your hands on.
Good Luck,
Stan
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
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volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to
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and follow the instructions there.
Keithley offer a Low Level Measurements Handbook that may be of interest. Go to www.keithley.com, Knowledge Centre. The digital book is a free download (requires registration). You may be able to get a paperback copy from your local Keithley rep just for the asking.
Regards,
Laurence Motteram
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On Behalf Of Stan Katz
Sent: Wednesday, 20 August 2014 9:35 AM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] What's All This Low Thermal EMF Test Lead Stuff?
You are on the money that guarding/shielding are sadly neglected as subjects, in their own right. Posts in this group consist primarily of reports of guard leakage in member instruments, and repair details.
Discussion of proper lash ups of cal. instruments to home built devices, or even work prototypes, would be very welcome by me. I have read Analog Devices AN-347, but a tutorial with problems that the student must complete the lash ups for, would give me a better idea if I've grasped the subject matter. There are two text books mentioned at the end of AN-347, one by Morrison, the other by Ott. Any suggestion as to which to buy? The latest texts by these authors are pricey, so that's why I'd like to pick just one.
On Tue, Aug 19, 2014 at 3:37 AM, acbern@gmx.de wrote:
generally I think, and at least for your gear, if you use copper plugs
of some type and even solder the wires, thats perfectly fine.
also for a 3458a, and after proper temp stabilization after connecting
the cables (5min) which you always need, these are fine, have not
measrured any difference to crimped cables. also the type of cable
plating (tin/silver..) does not make much difference.
there were many discussions over time, but all the cadmium solder and
non plated copper type debates are not making much sense down to the
3458a level.
I have not done comparison tests with nanovolt meters, as mine have
fixed cables, so no option to change them without destroying them, but
note that e.g. the 182 nanovolt meter has a mil type plug (no special contacts).
sources of error are also things like where to connect the guard to,
these often make a much bigger difference (I have seen these many
times, causing voltage differences of several uV depending where in
the setup you connected the guard, while otherwise the measurement was
perfectly stable), and I bet while people put a lot of effort into the
emf discussion, the guard issue is more often causing errors in
measurements in real life. and thats just one example of additional causes of errors.
cheers
Gesendet: Dienstag, 19. August 2014 um 06:07 Uhr
Von: "Stan Katz" stan.katz.hk@gmail.com
An: "Discussion of precise voltage measurement" volt-nuts@febo.com
Betreff: [volt-nuts] What's All This Low Thermal EMF Test Lead Stuff?
I'm a self described volt-nut-near-beer. I don't own a 732A/B, or an
HP3458. I do own HP3456 DMMs that are at the top of my
instrumentation pecking order. I have all the necessary gear to
calibrate these DMMs according to ancient HP documentation. At the
top of my cal. chain is the 731B, called out in HP3456 original
documentation. This hierarchy places me in the near-beer, or junior
member status of the group. I look forward to being educated, and/or
corrected on my understanding of the use of
test
leads with precision instrumentation.
I don't find much ancient HP documentation on test leads. The only
recommendations in the era of the 3456 back to the 1960's is to use
as thick a solid lead of pure copper wire as you can find, and
insert the
wire
into the drill hole on the banana terminal. If the copper is pure,
and
has
been properly cleaned, the thermal emf's on both identical length
leads should all be balanced, and cancel out. In any case, pure
copper-copper connections generate the lowest thermal emf. I will
agree that
manhandling
16 gauge solid wire can be very inconvenient.
The path I have taken recently is to order Nakamichi gold over
copper stereo banana plugs for my connections ( I deal in low
voltage work exclusively), as well as gold plated spade lugs to go
under the banana screw-downs. ( My budget ruled out gold over
beryllium copper Pomona
brand
spades. ) I will then experiment between the two connector types.
As for connections, it seems to me the best course is just to screw
down the banana plugs, or in the case of the spades, just crimp.
I'll wing it on
the
crimping, and see if simple tools can perform adequately. I would
avoid solder, since how can one form identical topological spots of
solder on every connection, deposited at the exact same place on
each connection,
and
ensure the exact same weight of solder, to the microgram, on each
connection. Since my modus operandi is to aim for balanced emfs, I
think solder is out. Of course, if one wishes to risk one's health,
and that of the family, one can track down a source of cadmium, and
mix up a lot of
low
thermal emf solder (cadmium solder is banned in the US, and
EU)...not for me.
Don't worry, I won't be using tin plated wire, I managed to pick up
a
spool
of silver plated 16 gauge wire for my investigations. Am I on some
other planet for choosing the balanced thermal emf approach for
precision test lead applications, as opposed to going to great
lengths to eliminate
every
trace of emf?
Please forgive me if these emf discussions have been between
engineers working outdoors in the oil fields of North Dakota, or out
on a North Sea drilling platform. In that case, go for all the super
low emf techniques you can lay your hands on.
Good Luck,
Stan
volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to
and follow the instructions there.
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Message protected by MailGuard: e-mail anti-virus, anti-spam and content filtering.
http://www.mailguard.com.au
Stan,
Both the Fluke Calibration: Philosophy in Practice and the Keithley: Low Level
Measurements Handbook have chapters about grounding and guarding. The Low Level
handbook is available from Keithley as a download:
http://www.keithley.com/knowledgecenter/knowledgecenter_pdf/LowLevMsHandbk.pdf
For the 1978-1980 version of the Fluke book:
https://archive.org/details/Calibration-PhilosophyInPractice
The Kindle and epub versions are not very good; get the 32 MB pdf file.
Joe Hobart
On 8/19/2014 5:50 PM, Todd Micallef wrote:
Stan,
I have seen this Fluke book mentioned occasionally. I am not sure if has
the tutorials that you seek. It is advertised as specific to dc/ lf ac.
http://www.amazon.com/Calibration-Philosophy-Practice-Fluke-Corporation/dp/0963865005
Todd
On Tue, Aug 19, 2014 at 7:35 PM, Stan Katz stan.katz.hk@gmail.com wrote:
You are on the money that guarding/shielding are sadly neglected as
subjects, in their own right. Posts in this group consist primarily of
reports of guard leakage in member instruments, and repair details.
Discussion of proper lash ups of cal. instruments to home built devices, or
even work prototypes, would be very welcome by me. I have read Analog
Devices AN-347, but a tutorial with problems that the student must complete
the lash ups for, would give me a better idea if I've grasped the subject
matter. There are two text books mentioned at the end of AN-347, one by
Morrison, the other by Ott. Any suggestion as to which to buy? The latest
texts by these authors are pricey, so that's why I'd like to pick just one.
Fellow Volt-Nuts
If I can put a recommendation in for an Australian publication, NMI
Australia runs courses in Electrical Measurements and publishes a monograph
of the course.
Monograph 6 The Measurement of Electrical Quantities (2009, third edition)
Ilya Budovsky et al, 140 pp ($125, overseas $140)
The monograph describes principles and techniques of the measurement of
electrical quantities (direct and alternating voltage, direct and
alternating current, resistance and high voltage), particularly with the use
of digital multimeters (DMMs) and calibrators. The emphasis is on the
techniques of reliable measurement and this necessarily involves a detailed
discussion of the systematic errors that affect the measurement of
electrical quantities as well as the principles of operation of DMMs and
calibrators. Also discussed is the calibration of DMMs and the calculation
of the uncertainty of calibration. The monograph gives an introduction to
the primary standards of electrical quantities.
There is a good section on guarding in this publication; the different types
and correct/incorrect methods of guarding.
It can be ordered through
http://measurement.gov.au/Publications/Pages/Monographs.aspx there is a link
at the top to download a pdf order form.
If you are looking for a free publication I like the Keithley publication
and I vaguely remember Hewlett Packard (as they were then) in the 1970's or
1980's publishing an application note on this subject (a search through the
HP ap note archive may show which one) or Keysight may still have it on
their website.
Kind Regards,
Stephen Grady
Sydney, Australia
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On
Behalf Of Stan Katz
Sent: Wednesday, 20 August 2014 9:35 AM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] What's All This Low Thermal EMF Test Lead Stuff?
You are on the money that guarding/shielding are sadly neglected as
subjects, in their own right. Posts in this group consist primarily of
reports of guard leakage in member instruments, and repair details.
Discussion of proper lash ups of cal. instruments to home built devices, or
even work prototypes, would be very welcome by me. I have read Analog
Devices AN-347, but a tutorial with problems that the student must complete
the lash ups for, would give me a better idea if I've grasped the subject
matter. There are two text books mentioned at the end of AN-347, one by
Morrison, the other by Ott. Any suggestion as to which to buy? The latest
texts by these authors are pricey, so that's why I'd like to pick just one.
On Tue, Aug 19, 2014 at 3:37 AM, acbern@gmx.de wrote:
generally I think, and at least for your gear, if you use copper plugs
of some type and even solder the wires, thats perfectly fine.
also for a 3458a, and after proper temp stabilization after connecting
the cables (5min) which you always need, these are fine, have not
measrured any difference to crimped cables. also the type of cable
plating (tin/silver..) does not make much difference.
there were many discussions over time, but all the cadmium solder and
non plated copper type debates are not making much sense down to the
3458a level.
I have not done comparison tests with nanovolt meters, as mine have
fixed cables, so no option to change them without destroying them, but
note that e.g. the 182 nanovolt meter has a mil type plug (no special
contacts).
sources of error are also things like where to connect the guard to,
these often make a much bigger difference (I have seen these many
times, causing voltage differences of several uV depending where in
the setup you connected the guard, while otherwise the measurement was
perfectly stable), and I bet while people put a lot of effort into the
emf discussion, the guard issue is more often causing errors in
measurements in real life. and thats just one example of additional causes
of errors.
cheers
Gesendet: Dienstag, 19. August 2014 um 06:07 Uhr
Von: "Stan Katz" stan.katz.hk@gmail.com
An: "Discussion of precise voltage measurement" volt-nuts@febo.com
Betreff: [volt-nuts] What's All This Low Thermal EMF Test Lead Stuff?
I'm a self described volt-nut-near-beer. I don't own a 732A/B, or an
HP3458. I do own HP3456 DMMs that are at the top of my
instrumentation pecking order. I have all the necessary gear to
calibrate these DMMs according to ancient HP documentation. At the
top of my cal. chain is the 731B, called out in HP3456 original
documentation. This hierarchy places me in the near-beer, or junior
member status of the group. I look forward to being educated, and/or
corrected on my understanding of the use of
test
leads with precision instrumentation.
I don't find much ancient HP documentation on test leads. The only
recommendations in the era of the 3456 back to the 1960's is to use
as thick a solid lead of pure copper wire as you can find, and
insert the
wire
into the drill hole on the banana terminal. If the copper is pure,
and
has
been properly cleaned, the thermal emf's on both identical length
leads should all be balanced, and cancel out. In any case, pure
copper-copper connections generate the lowest thermal emf. I will
agree that
manhandling
16 gauge solid wire can be very inconvenient.
The path I have taken recently is to order Nakamichi gold over
copper stereo banana plugs for my connections ( I deal in low
voltage work exclusively), as well as gold plated spade lugs to go
under the banana screw-downs. ( My budget ruled out gold over
beryllium copper Pomona
brand
spades. ) I will then experiment between the two connector types.
As for connections, it seems to me the best course is just to screw
down the banana plugs, or in the case of the spades, just crimp.
I'll wing it on
the
crimping, and see if simple tools can perform adequately. I would
avoid solder, since how can one form identical topological spots of
solder on every connection, deposited at the exact same place on
each connection,
and
ensure the exact same weight of solder, to the microgram, on each
connection. Since my modus operandi is to aim for balanced emfs, I
think solder is out. Of course, if one wishes to risk one's health,
and that of the family, one can track down a source of cadmium, and
mix up a lot of
low
thermal emf solder (cadmium solder is banned in the US, and
EU)...not for me.
Don't worry, I won't be using tin plated wire, I managed to pick up
a
spool
of silver plated 16 gauge wire for my investigations. Am I on some
other planet for choosing the balanced thermal emf approach for
precision test lead applications, as opposed to going to great
lengths to eliminate
every
trace of emf?
Please forgive me if these emf discussions have been between
engineers working outdoors in the oil fields of North Dakota, or out
on a North Sea drilling platform. In that case, go for all the super
low emf techniques you can lay your hands on.
Good Luck,
Stan
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About the Keithley mentioned by stephen, It is a free download but they have a free paper version too. I have a picture of it on my site. Scroll down until you see a red book. http://www.pa4tim.nl/?p=2899
Fred, pa4tim
Verzonden met Windows Mail
Van: Stephen Grady
Verzonden: woensdag 20 augustus 2014 06:31
Aan: volt-nuts
Fellow Volt-Nuts
If I can put a recommendation in for an Australian publication, NMI
Australia runs courses in Electrical Measurements and publishes a monograph
of the course.
Monograph 6 The Measurement of Electrical Quantities (2009, third edition)
Ilya Budovsky et al, 140 pp ($125, overseas $140)
The monograph describes principles and techniques of the measurement of
electrical quantities (direct and alternating voltage, direct and
alternating current, resistance and high voltage), particularly with the use
of digital multimeters (DMMs) and calibrators. The emphasis is on the
techniques of reliable measurement and this necessarily involves a detailed
discussion of the systematic errors that affect the measurement of
electrical quantities as well as the principles of operation of DMMs and
calibrators. Also discussed is the calibration of DMMs and the calculation
of the uncertainty of calibration. The monograph gives an introduction to
the primary standards of electrical quantities.
There is a good section on guarding in this publication; the different types
and correct/incorrect methods of guarding.
It can be ordered through
http://measurement.gov.au/Publications/Pages/Monographs.aspx there is a link
at the top to download a pdf order form.
If you are looking for a free publication I like the Keithley publication
and I vaguely remember Hewlett Packard (as they were then) in the 1970's or
1980's publishing an application note on this subject (a search through the
HP ap note archive may show which one) or Keysight may still have it on
their website.
Kind Regards,
Stephen Grady
Sydney, Australia
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On
Behalf Of Stan Katz
Sent: Wednesday, 20 August 2014 9:35 AM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] What's All This Low Thermal EMF Test Lead Stuff?
You are on the money that guarding/shielding are sadly neglected as
subjects, in their own right. Posts in this group consist primarily of
reports of guard leakage in member instruments, and repair details.
Discussion of proper lash ups of cal. instruments to home built devices, or
even work prototypes, would be very welcome by me. I have read Analog
Devices AN-347, but a tutorial with problems that the student must complete
the lash ups for, would give me a better idea if I've grasped the subject
matter. There are two text books mentioned at the end of AN-347, one by
Morrison, the other by Ott. Any suggestion as to which to buy? The latest
texts by these authors are pricey, so that's why I'd like to pick just one.
On Tue, Aug 19, 2014 at 3:37 AM, acbern@gmx.de wrote:
generally I think, and at least for your gear, if you use copper plugs
of some type and even solder the wires, thats perfectly fine.
also for a 3458a, and after proper temp stabilization after connecting
the cables (5min) which you always need, these are fine, have not
measrured any difference to crimped cables. also the type of cable
plating (tin/silver..) does not make much difference.
there were many discussions over time, but all the cadmium solder and
non plated copper type debates are not making much sense down to the
3458a level.
I have not done comparison tests with nanovolt meters, as mine have
fixed cables, so no option to change them without destroying them, but
note that e.g. the 182 nanovolt meter has a mil type plug (no special
contacts).
sources of error are also things like where to connect the guard to,
these often make a much bigger difference (I have seen these many
times, causing voltage differences of several uV depending where in
the setup you connected the guard, while otherwise the measurement was
perfectly stable), and I bet while people put a lot of effort into the
emf discussion, the guard issue is more often causing errors in
measurements in real life. and thats just one example of additional causes
of errors.
cheers
Gesendet: Dienstag, 19. August 2014 um 06:07 Uhr
Von: "Stan Katz" stan.katz.hk@gmail.com
An: "Discussion of precise voltage measurement" volt-nuts@febo.com
Betreff: [volt-nuts] What's All This Low Thermal EMF Test Lead Stuff?
I'm a self described volt-nut-near-beer. I don't own a 732A/B, or an
HP3458. I do own HP3456 DMMs that are at the top of my
instrumentation pecking order. I have all the necessary gear to
calibrate these DMMs according to ancient HP documentation. At the
top of my cal. chain is the 731B, called out in HP3456 original
documentation. This hierarchy places me in the near-beer, or junior
member status of the group. I look forward to being educated, and/or
corrected on my understanding of the use of
test
leads with precision instrumentation.
I don't find much ancient HP documentation on test leads. The only
recommendations in the era of the 3456 back to the 1960's is to use
as thick a solid lead of pure copper wire as you can find, and
insert the
wire
into the drill hole on the banana terminal. If the copper is pure,
and
has
been properly cleaned, the thermal emf's on both identical length
leads should all be balanced, and cancel out. In any case, pure
copper-copper connections generate the lowest thermal emf. I will
agree that
manhandling
16 gauge solid wire can be very inconvenient.
The path I have taken recently is to order Nakamichi gold over
copper stereo banana plugs for my connections ( I deal in low
voltage work exclusively), as well as gold plated spade lugs to go
under the banana screw-downs. ( My budget ruled out gold over
beryllium copper Pomona
brand
spades. ) I will then experiment between the two connector types.
As for connections, it seems to me the best course is just to screw
down the banana plugs, or in the case of the spades, just crimp.
I'll wing it on
the
crimping, and see if simple tools can perform adequately. I would
avoid solder, since how can one form identical topological spots of
solder on every connection, deposited at the exact same place on
each connection,
and
ensure the exact same weight of solder, to the microgram, on each
connection. Since my modus operandi is to aim for balanced emfs, I
think solder is out. Of course, if one wishes to risk one's health,
and that of the family, one can track down a source of cadmium, and
mix up a lot of
low
thermal emf solder (cadmium solder is banned in the US, and
EU)...not for me.
Don't worry, I won't be using tin plated wire, I managed to pick up
a
spool
of silver plated 16 gauge wire for my investigations. Am I on some
other planet for choosing the balanced thermal emf approach for
precision test lead applications, as opposed to going to great
lengths to eliminate
every
trace of emf?
Please forgive me if these emf discussions have been between
engineers working outdoors in the oil fields of North Dakota, or out
on a North Sea drilling platform. In that case, go for all the super
low emf techniques you can lay your hands on.
Good Luck,
Stan
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and follow the instructions there.
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