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 -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
