Agilent Kelvin Probe Lead Set 11059A For 34410A

[JoeN]

http://www.keysight.com/en/pd-1000000311%3Aepsg%3Apro-pn-11059A/kelvin-probe-set?cc=US&lc=eng

I was doing some 4-wire resistance measurements with two normal Agilent lead sets (34138A) with the grabbers attached.  Good results, as far as I can see.  I see Agilent has a special lead set for that function.  Does this thing really outperform using two normal lead sets?  And what's with the fifth ground lead?  I am not even sure where that is supposed to go for the 34410A.  Thanks.

[VK5RC]

Make your own Kelvin leads,  Franky Tong (i think ebay ft-2000, his handle is iloveelectronics)  has some of the nice clamps,  and some nice cable wwit reasonable plugs and you are set!

[Gyro]

The fifth ground lead is probably just be an electrostatic shield for reducing noise pickup on high value resistance measurements. It's normally connected to the Guard terminal but I don't think the 34410a has one of these. You'd probably connect it to one of the Ohms drive terminals, whichever one gives the quietest reading.

Some meters have an active ohms guard lead to remove the effect of stray leakage paths shunting the resistor under test (in circuit) but then it would include an extra clip too.

[Stray Electron]

  I just finished rebuilding the 1657-9600 Extender Cable set for my GR 1657 Didibridge. It is similar to this cable set and also uses four measurements leads with a fifth lead for ground. Each lead is a shielded low capacitance coaxial cable and all of the shields are tied together at the instrument end and connected to fifth lead and it is connected to a frame ground (NOT one of the measurement leads) of the UUT.  Even though the Digibridge only tests at 120 Hz and 1 kHz, I've noticed that the readings are much more stable when the ground lead is connected and the shields are grounded.

  In the Digibridge, if you connect the ground lead to any of the four measurement leads, it will badly distort the readings.  The GR manual specifically tells you not to do that.

[JoeN]

Make your own Kelvin leads,  Franky Tong (i think ebay ft-2000, his handle is iloveelectronics)  has some of the nice clamps,  and some nice cable wwit reasonable plugs and you are set!

I can't see him or his listings on eBay.  I tried ft-2000, ft2000, frankytong, none of these sellers exist.  I will look for him here and see if I can find his posts.  It seemed all the cheap leads on eBay have BNC ends , not "standard multimeter" ends, whatever those are called, I think because LCR meters use them.  I would like them with multimeter ends if possible and under $50 too if possible.

Found him by search here.  He lists his eBay store in his tagline.  http://stores.ebay.com/99centhobbies

I see he specializes in leads and jumpers.  I don't see any 4-wire ground shielded sets though.  I will keep looking...

The fifth ground lead is probably just be an electrostatic shield for reducing noise pickup on high value resistance measurements.

Odd, my higher value measurements were rock solid, but frankly I only went up to 2K because I don't see the value of using 4-wire on high resistance measurements, they are already accurate with 2 wires.  I wanted the measurement to remove the contribution of the leads to the resistance measurement.  I measured 2K because I have a very high precision .01% Vishay 2K resistor and that measured out as 1,999.997 or something like that at 10NPLC integration time and was rock solid.  My measurement of a .1 ohm "1%" resistor was pretty solid (but not actually 1% LOL - thanks random eBay seller).  The measurement of a .005 ohm resistor was rather less solid, even at 100NPLC, it rolled around a bit.  Maybe that is getting near the limit of what the meter can reasonably do.  Maybe that is what the 34420A is for.

I've noticed that the readings are much more stable when the ground lead is connected and the shields are grounded.

Yeah, maybe this will help at stability for the low value measurements that rolled around a bit.  If I got a probe set with the ground lead where should I ground it since the 34410A has no ground input.  Just ground it directly to earth ground?   I have an earth ground available at my bench that goes right down to the basement and connects to a cast iron water pipe that runs outside.  Best ground that I could think of.  I use it as the ground for my anti-static pad.  Most everything else is grounded through the third outlet prong.

Anyone with a link to leads that are compatible with a 34410A would be appreciated. 

[Vgkid]

@ Stray Electron
Can you post pics. Someone butchered up the wiring of my GR BNC connector box, added an interestng test jig.

[BravoV]

Frankie's offering is not officially listed, its buried deep in his sales thread, click -> HERE

Just ordered one set recently for my bench LCR meter, its definitely worth the money.

[Stray Electron]

@ Stray Electron
Can you post pics. Someone butchered up the wiring of my GR BNC connector box, added an interestng test jig.

  Sure but what do you need pictures of?  There's not much to see and there's pictures on the internet, particularly on E-bay. http://www.ebay.com/itm/GR-GenRad-QuadTech-IET-1689-Precision-RLC-Digibridge-with-GPIB-0-02-accy-/321801824109?hash=item4aece2276d and http://www.ebay.com/itm/GR-Genrad-P-N-1657-9600-1657-1659-1689-1692-Etc-Digibridge-Test-Adapter-Exc-/252014531172?pt=LH_DefaultDomain_0&hash=item3aad3c9264&nma=true&si=%252Bm9doWZV6oHWyRwLv6nbcbxs%252Fgw%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557.  You'll need to log into E-bay to see the 2nd one.

    FWIW I had another Digibridge before I got this one with the test adapter. I made my own adapter for it out of small piece of thin, double sided PCB about 2 inches square and it seems to work as well as the factory one. I just had to make a vertical cut on each side of the PCB so that I ended up with four contacts. The front two contacts are the current source ( - on the left and + on the right) and the back two are the voltage sense (again  - on the left and + on the right). The connector portion of factory test cable is mounted in a plastic block and has two thumb screws in it so that you can attach it to the Digibridge but I just plug mine in and it works fine.

    FYI, the factory test cables have a stackable banana plug/socket molded on on the end of each wire. I found three out of the four on mine had broken wires inside of the leads next to the banana jack and they were causing intermittent readings so I had to cut them off and replace them. The only stackable banana jacks that I could find used set screws to hold the wire so I'm not thrilled with that but they were all that I could find at the time and they are working ok, at least for now.

   Let me know if you need pictures of something specific and I'll try to get some.

[JoeN]

The most important thing I learned from this whole conversation:  Fluke and Agilent multimeters use simple banana jacks (for instruments) and connectors (for probes).  When I look at the long shrouded connector and the insulator at the top of the conductor that obscures the banana connector itself, it doesn't look anything like a banana connector to me, I don't see it.  Now I get it, a simple banana connector works fine when plugged into the meter, it's just the factory probes are really shrouded up for high voltage safety reasons.  So that's a good thing to know and I had  been missing it all along.