Electrometer cables, probes, etc - Page 1
Forum section: electronics / testgear

author: cncjerry
author_rank: Unknown
timestamp: February 18, 2017, 08:21:04 pm
content: I bought a Keithley 616 recently and as I am making up cables, I am wondering what others use in terms of terminations. For instance, the first cable I made I put decent clips on it. So I used a triax cable of about 24" long and split the end into three wires with high quality clips. I recently bought some more triax connectors from a great guy, n2cau. He has Trompeter PL75-24A Triax Triaxial Cable Connector - Military NSN 5935010754440 for sale and after buying them, they would't fit my cable. So we traded messages, he has a number of links on his sight that outline the connectors and corresponding cables, but he went so far as to ship me about 10M of cable after the fact. Never expected it, just opened the mail and there it was. We had traded about 5 or 6 emails prior to him sending the cable. The cable by the way was used in missiles and even after spitting the end, I can run the Electrometer up to its highest range without a problem.With my connectors (he also sent more connectors with the cable for free I might add) and all the cable I have, I am wondering what I should make up. My current thinking is to keep the triax to clips as is, make one that is triax to banana plugs, maybe another to a set of smaller clips and was also thinking of one that terminates in two clips and a banana so I can use the banana for connecting to a probe and the clips for the ground and guard.So I guess that's the question, is it practical to probe high impedance circuits? Should I bother with the probe? I'm also wondering if it is worth while to have triax to banana because how often would you need an Electrometer to measure something that terminates in banana jacks? So I'm thinking of skipping the banana jack version and just have two sets of clips, one larger and one smaller like those used for clipping to IC leads.Anyway, the Electrometer is a pretty handy device once you figure out the whole cabling/connector issues.Thanks

author: TerraHertz
author_rank: Super Contributor
timestamp: February 20, 2017, 03:27:28 am
content: What's n2cau's web site?I'm been searching for some odd triax connectors for ages. (For HP 3567A, seehttp://everist.org/spacejunk/want/Parts_I_need.htm)

author: Assafl
author_rank: Frequent Contributor
timestamp: February 21, 2017, 06:01:08 pm
content: I made 2 cables - one with a probe (don't know why - don't use it) and one terminated with three wires that end with single pin Dupont (0.1mm) headers. These can plug onto miniature grabbers and anything else that has a pin soldered to it. I soldered pins to crocs as well.I could not find a croc or even a grabber that can be touched while measuring (they are all practically short as far as the 616 is concerned on the higher ranges).All wires were Teflon, and due to opportunity I kept the guarding all the way to the header (the last wire I used was a shielded laptop antenna wire - which was teflon). All insulation was Teflon as well, with the entire connection area in shrink tubing (Polyeofin).The probe needed Teflon inserts as well.

author: cncjerry
author_rank: Unknown
timestamp: February 22, 2017, 02:34:21 am
content: n2cau is on eBay.Assafl, was that a female header so you can plug into little grabbers and others, I guess, that we can solder other pins onto. Good idea.

author: tggzzz
author_rank: Super Contributor
timestamp: February 22, 2017, 01:15:30 pm
content: Quote from: cncjerry on February 22, 2017, 02:34:21 amNot that I can see. Can you post a URL to something they sell, or to their shop, etc?

author: Assafl
author_rank: Frequent Contributor
timestamp: February 22, 2017, 02:29:05 pm
content: Yes - female single pin headers.But don't touch them when measuring. That PVC (or whatever black plastic they use) is a virtual short on the high ranges of the electrometer.I'll probably shrink Teflon on them (if I ever get the shrink Teflon from china and it actually works).

author: cncjerry
author_rank: Unknown
timestamp: February 22, 2017, 05:16:39 pm
content: Try this link:http://www.ebay.com/itm/Trompeter-PL75-24A-Triax-Triaxial-Cable-Connector-Military-NSN-5935010754440-/142261005467?hash=item211f6aac9b:g:AUoAAOSwopRYjTfZ]http://www.ebay.com/itm/Trompeter-PL75-24A-Triax-Triaxial-Cable-Connector-Military-NSN-5935010754440-/142261005467?hash=item211f6aac9b:g:AUoAAOSwopRYjTfZSorry, his ID is n2cbu, not n2cau. Going to re-learn my alphabet. Have been practicing it backwards for so long because I had heard that was a sobriety test here locally.You can also send him a note asking for some of the raychem cable that fits these connectors perfectly.

author: krish2nasa
author_rank: Newbie
timestamp: September 11, 2017, 03:59:34 am
content: @cncjerry How much did you pay for PL75-24A Triax Triaxial Cable Connector? Did you try using Belden 9222 Triax cable?Thanks,-Krish

author: Berni
author_rank: Super Contributor
timestamp: September 11, 2017, 05:14:04 am
content: I got a Keithley 617 electrometer in repair right now, already troubleshooted it, just waiting on spare parts.However i found out that the triax BNC on the back has the 2 bump 180 deg bayonet locking nut found on normal BNCs rather than the 3 bump 120 deg locking nut that all of my cables have.Im probably going to grab a few of those triax connectors anyway since its nice to have spares of these damn things. Thanks for the link.

author: coldframe
author_rank: Regular Contributor
timestamp: September 12, 2017, 05:06:07 am
content: Quote from: krish2nasa on September 11, 2017, 03:59:34 amHello krish2nasaBelden 9222 of O.D is .242", Fit POMONA 5218I think TL74-24A is TROMPETR TRC-50-1 MatchesAttatchedthis is a fit TL74-24A Cable (O.D 0.150")