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 <tmical...@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...@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.
