On Sun, Aug 24, 2014 at 1:46 PM, Don@True-Cal <truecalservi...@gmail.com> wrote:
> Randy & all, > > You have correctly concluded that some (maybe not all) of your measurement > problem is thermal EMF being added or subtracted in series within your > measurement interconnect. This thermal EMF is generated at the junction of > dissimilar metals when accompanied with thermal gradients between the test > lead and device terminals. You have to eliminate both the dissimilarity of > the metal junctions as well as minimize the thermal differences. The > terminals of the 3458A as well as the 732A are Beryllium Copper so you want > to use the same test lead terminals. Forget the typical Tin plated lugs or > even Gold plated as both are not Beryllium Copper and constitute dissimilar > metals. The best solution (as usually the most expensive) is to use a set > of > Fluke 5440A-7005 (48") cables. I also have just as good results using the > much more flexible Pomona 11174A (lugs end always stay connected to the > 732A) or 11058A with more convenient shielded banana plugs. The Fluke cable > has the added Guard built in but be sure to also use a Guard lead with the > Pomona cabled. The Guard lead does not need to be low thermal EMF. DIY > cables is usually not a good idea because the lead wire to terminal also > constitutes just as critical of junction. The above cables use Tellurium > Copper wire which is usually hard to find and hard to crimp properly and > NEVER solder. > 11058A and 11174A are discontinued at Keysight. However, Pomona 5295 spade to banana cables are available (5295-36 at Mouser et al) and claim that they are designed to minimize thermal EMFs. Datasheet is here: http://www.mouser.com/ds/2/159/d5295_1_01-51722.pdf Any comments on these as an alternative? Orin. _______________________________________________ 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.
