A
acbern@gmx.de
Wed, Aug 20, 2014 8:57 AM
if you buy a voltage source that is cal'ed to 6ppm you do not end uop with a factor of 10 (60ppm). the fatcor of 10 is often used to be on the safe side, but in high percision cals 10 is not achievable anyways. some mil standards call for 4, but what you should do is to analyze the error propagation and then determine the likely final uncertainty (you would do this with a certain confidence level, say 95% which is usual). so you would look at the different contributors (temo variation, aging since call'ed, error due to emf voltage and so on). you would add these up by the rss (root sum square) method.
there is a lot of literature out there for this, also free on the net, and it would not be possible to describe the details here, but I would suggest to do this, as the real error will be much better I am sure.
Gesendet: Mittwoch, 20. August 2014 um 03:03 Uhr
Von: "Stan Katz" stan.katz.hk@gmail.com
An: "Discussion of precise voltage measurement" volt-nuts@febo.com
Betreff: Re: [volt-nuts] What's All This Low Thermal EMF Test Lead Stuff?
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:
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
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
into the drill hole on the banana terminal. If the copper is pure, and
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
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
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
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,
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
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
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
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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To unsubscribe, go to
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and follow the instructions there.
if you buy a voltage source that is cal'ed to 6ppm you do not end uop with a factor of 10 (60ppm). the fatcor of 10 is often used to be on the safe side, but in high percision cals 10 is not achievable anyways. some mil standards call for 4, but what you should do is to analyze the error propagation and then determine the likely final uncertainty (you would do this with a certain confidence level, say 95% which is usual). so you would look at the different contributors (temo variation, aging since call'ed, error due to emf voltage and so on). you would add these up by the rss (root sum square) method.
there is a lot of literature out there for this, also free on the net, and it would not be possible to describe the details here, but I would suggest to do this, as the real error will be much better I am sure.
> Gesendet: Mittwoch, 20. August 2014 um 03:03 Uhr
> Von: "Stan Katz" <stan.katz.hk@gmail.com>
> An: "Discussion of precise voltage measurement" <volt-nuts@febo.com>
> Betreff: Re: [volt-nuts] What's All This Low Thermal EMF Test Lead Stuff?
>
> 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 ...
> >
> > 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.
> > >
> > _______________________________________________
> > 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.
>
MW
Mark Wendt
Wed, Aug 20, 2014 9:09 AM
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.
This could devolve into a beer-nuts-nuts group too. One must have one's
beer-nuts whilst sipping beer whilst perusing the beer-nuts group.
Mark
On Tue, Aug 19, 2014 at 9:03 PM, Stan Katz <stan.katz.hk@gmail.com> wrote:
> 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.
>
>
>
>
This could devolve into a beer-nuts-nuts group too. One must have one's
beer-nuts whilst sipping beer whilst perusing the beer-nuts group.
Mark