[volt-nuts] 732A and Prologix received

[Orin Eman]

On Sun, Aug 24, 2014 at 1:46 PM, Don at True-Cal <truecalservices at 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.