My TRIAX cable shielded box project for Keithley Instruments - Page 1
Forum section: electronics / general

author: HighVoltage
author_rank: Super Contributor
timestamp: December 03, 2016, 04:23:32 pm
content: Project 1This is my first attempt to build a shielded box with a TRIAX Cable to measure very high resistance values with my Keithley 614 Electrometer. This meter has the dual pin TRIAX connector and I found a fitting cable.These are the highlights of the materials used:- Metal box with metal lid- Bottom and side of the box covered with 5 mm thick PTFE (Teflon) plates- Original Keithley TRIAX cable- Outside shielding connected to the metal box (blue cable)- Inside shielding extended with copper/silver-plated cable and Teflon insulation (orange cable), (crimped)- Inner core extended with copper/silver-plated cable and Teflon insulation (orange cable), (crimped)- Crocodile clips pure copper (crimped)This Russian military glass resistor inside the box is marked with 100 GOhm and reads very stable 95.5 GOhm after a few minutes of not touching anything. So far I am happy with this box for this older Keithley 614 Electrometer.OK, I am looking for improvements and hints of what to change or do differently for the next project.My next box will be for the DMM7510 and 2450 SMU (3 pin TRIAX)One improvement I would probably use are Triax Panel Mount Connectors.But they are sooo expensive, same as withe the TRIAX cables.Thanks for any suggestions.

author: VintageNut
author_rank: Frequent Contributor
timestamp: December 03, 2016, 04:54:12 pm
content: Remove the resistor from the box. Leave the alligator clips where they were. Close the box. Force maximum voltage and measure current. This will tell you if you have any leakage.

author: plesa
author_rank: Frequent Contributor
timestamp: December 03, 2016, 05:31:07 pm
content: Fisher make triax which are cheaper than BNC ones. Or SHV or MHV ( high voltage BNC) are another option.White panels are from PTFE?If you want to make experiments with photodiodes I propose to put some black paper to panels.And add temperature and humidity measurement.If you are going to make some HV experiments add protection to your electrometer (GDT, 1M-100k resistors and two antiparalell diodes 1N3595 or DPAD1 are good).

author: manganin
author_rank: Regular Contributor
timestamp: December 03, 2016, 05:44:01 pm
content: Quote from: HighVoltage on December 03, 2016, 04:23:32 pmI did something similar last year.A cheap cash box (from Lidl) with a row of BNC feedthroughs (one triax) and a flexible copper strap connecting the top and the bottom.Two of the connectors with fixed crocodile clips for measuring resistors. No wires or components touching the box = no leakage path.

author: quarks
author_rank: Frequent Contributor
timestamp: December 03, 2016, 09:28:29 pm
content: very interesting, thanks for sharingI just saw this Videoin there I saw Agilent box (around 4:06min it is large in the frame)

author: HighVoltage
author_rank: Super Contributor
timestamp: December 04, 2016, 11:11:04 am
content: Quote from: VintageNut on December 03, 2016, 04:54:12 pmVintageNutGood idea but first I need to get a TRIAX to "something else adapter", so I can apply the voltage to the same input cable.My Keithley Pico Amp Meter will probably be helpful for this test.plesaSince the Keithley 2450 has already the 3 prong TRIAX connectors on the back, I think I will stay with them.One idea is to buy two cables and cut them in 1/2 to have 4 cablesBut I think I will make the box really nice with TRIAX Panel Mount Connector like in this pictures

author: HighVoltage
author_rank: Super Contributor
timestamp: December 04, 2016, 11:35:42 am
content: Quote from: quarks on December 03, 2016, 09:28:29 pmquarksThat was an interesting video, thanks.The box shown is an Agilent 16442B, its probably $10k, I would guess and looks really nice.Interestingly, they are using 2 mm banana plug connectors inside.

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: December 04, 2016, 01:03:39 pm
content: HP test fixtures like the 16058A are available on ebay though the quality and condition are not as nice as the one in the video. It looks like the enclosure is coated with a conductive shield.The 16058A has triax and BNC connectors already installed. It also uses modules for different components.

author: zlymex
author_rank: Frequent Contributor
timestamp: December 05, 2016, 02:57:12 am
content: Looking very nice.I got a Keithley 6104 test enclosure, and modified for triax connection, just in case you haven't seen that.https://www.eevblog.com/forum/metrology/i-plan-to-make-an-100-meg-standard-resistor/msg917093/#msg917093

author: VintageNut
author_rank: Frequent Contributor
timestamp: December 05, 2016, 04:02:49 pm
content: I acquired a KE 8002 high resistance test fixture. It matches perfectly for a KE 487 picoammeter that I also acquired.

author: macboy
author_rank: Super Contributor
timestamp: December 06, 2016, 06:57:35 pm
content: I guess I must have a little bit of OCD or something, because I cringe when I hear "Triax connector". Triax is a type of cable, not a specific connector. I suppose that any connector that fits Triax cable is a triax connector. By the same token, SMA, BNC, and RCA are all "Coax" connectors.The connector we are referring to is aTRB, also occasionally calledTrompeterafter a common manufacturer (like Kleenex or Q-tip). TRB connectors usually have 3 lugs rather than 2 these days to help prevent damage due to dummies mating them onto BNCs. To make it even more complicated, there are keyed versions where the angle between the lugs is not all 120o.The TRB connector is also commonly used with Twinax cable in addition to Triax. There is only a slight internal difference to ease termination of the cable, but the mating surfaces are identical; it's still a TRB connector.On a helpful note, you will find more hits for used (and especially new) cables and connectors if you expand your search to include TRB and Trompeter, since merchants often do not refer to them as Triax.

author: VintageNut
author_rank: Frequent Contributor
timestamp: December 06, 2016, 07:07:26 pm
content: Good points. My instruments have 2-lug triax and 3-lug triax connectors. Most have the 3-lug. Keithley discontinued the 2-lug connectors because you could insert a 2-lug coax plug which destroyed the 2-lug triax jack. The coax center pin is much larger the triax jack receptacle. The coax plug center pin forces the jack receptacle to expand and is ruined. I have witnessed this with a model 7065 Hall Effect switch card. It is a very expensive card and is easily ruined by unsuspecting users not aware of the difference between triax and coax.

author: dr.diesel
author_rank: Super Contributor
timestamp: December 06, 2016, 07:15:19 pm
content: Quote from: HighVoltage on December 04, 2016, 11:11:04 amThat is how I made mine:

author: HighVoltage
author_rank: Super Contributor
timestamp: December 06, 2016, 10:00:51 pm
content: Quote from: macboy on December 06, 2016, 06:57:35 pmThat was some very helpful information to find the correct binding posts. Thank you.

author: HighVoltage
author_rank: Super Contributor
timestamp: December 06, 2016, 10:10:12 pm
content: I found this really nice Keysight Video with some basic information to TRIAX / BNC wiringhttps://youtu.be/N66Oot1nJaQ

author: quarks
author_rank: Frequent Contributor
timestamp: December 07, 2016, 03:00:00 am
content: Also have a look at the great robrenz "DIY Triaxial test leads and shield Box" video

author: TiN
author_rank: Super Contributor
timestamp: December 13, 2016, 04:56:49 pm
content: Newcomers into high-impedance/low-current stuff don't understand why triaxial connectors cost arm and a leg? Well, opposite to regular cheap BNCs (high-frequency/high voltage version of BNCs are expensive as well!) triaxial connectors have significantly more bits and pieces into them and also machined to higher precision, use PTFE insulator (usually) and less qty product.Was making a cable for my low-current box using CNMC low-noise wire (with PTFE outer and inner insulation, graphite coated inner conductor insulator, copper braid, inner silver-plated copper braid, etc.) andCinch/Trompeter PL75-29 cable plug (23.5$)+Pomona 5219 (24$).

author: HighVoltage
author_rank: Super Contributor
timestamp: August 25, 2017, 05:04:10 pm
content: I am just starting again with this work in progress and everything I have learned from my first attempt above.Project 2This is now my second attempt to build a shielded box with 4 TRIAX Cable Connectors and 2 low emf binding posts, to measure very high resistance values and ultra low currents.This box is intended for theKeithley 2450 SMUandKeysight B2987A Electrometer.These are the highlights of the materials used so far:- Metal box with metal lid and hidges- Bottom and sides of the box will be covered with 5 mm thick PTFE (Teflon) plates- 4 pieces TRIAX connectors, modified to accept 2 mm banana plugs- 2 pieces LOW EMF binding posts, modified to accept 2 mm banana plugs- All inside wire connection will be made with gold plated 2 mm MC connectors- May be I will add 2mm gold tubes to the guard connectors as wellLater I will add:- Magnetic switch for the lid- PT100 Temperature sensor inside- Humidity sensor insideHere are the first pictures:Anything I am missing?

author: HighVoltage
author_rank: Super Contributor
timestamp: August 25, 2017, 05:22:30 pm
content: This is the modified Triax connector to accept the 2mm banana plugs

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: August 25, 2017, 07:06:39 pm
content: What does the Teflon do? I'd think it would cause more problems with surface charge and storage than anything else.

author: 4CX35000
author_rank: Regular Contributor
timestamp: August 25, 2017, 08:03:01 pm
content: Quote from: HighVoltage on August 25, 2017, 05:22:30 pmI have of doing the same to for my Keithley 617, but in my case I will make do with screwing the lid as normal. So long as the instrument is kept in a reasonably warm and dry enviornment, i don't see any reason in using the shielded box more once than every year.Farnell sell the Triaxial cable (Yellow outer), connectors can be bought from Farnell or RS Components and the rest inside my shielded box are standard gold plated components inside a stainless steel box.I decided to replace the two lug triaxial connectors with a three lug type on the Keithley 617 and do the same on my Keithley 220 DC Current Source, so both will need alignment and checking with the resistance box when ready.On the Keihtley 617 it has a voltage source facility which I checked yesterday and is working fine.

author: HighVoltage
author_rank: Super Contributor
timestamp: August 25, 2017, 08:55:32 pm
content: Quote from: Conrad Hoffman on August 25, 2017, 07:06:39 pmThe PTFE is for insulation purpose only, since I am planning to source up to 1000V in this box.On my Project 1 box above I used already teflon and did not notice any surface charge problems.But I will take a closer look at your interesting advise, thanks.

author: razberik
author_rank: Frequent Contributor
timestamp: August 25, 2017, 09:33:29 pm
content: Teardown of Keysight B2987A Electrometer please !Sorry for hijacking your topic.

author: HighVoltage
author_rank: Super Contributor
timestamp: August 27, 2017, 04:28:41 pm
content: Quote from: razberik on August 25, 2017, 09:33:29 pmI just ordered the B2987A from Keysight a couple weeks ago, it will probably arrive in 2 more weeks.Will see, if I have the guts to open it up.OK, I added the TRIAX connectors to the box and two LOW EMF copper tellurium / gold plated binding posts.Also added the PTFE plates inside. I even found a 3M double sided tape that sticks well to the Teflon.The cables are original Keithley 7078-TRX-3With the lid closed, this 100 GOhm resistor shows 95 GOhm very stable.But if I touch the box, the reading moves more than expected.Although the lid is grounded to the box, I need to add a screw to close it tightly, so touching the box will not influence the reading.Hmm, I might need a closing mechanism.

author: HighVoltage
author_rank: Super Contributor
timestamp: August 27, 2017, 04:56:06 pm
content: My largest resistor is one marked 1000 GigaOhm and it shows almost 1 TeraOhm.It is interesting how slow it climbs up from 0.9 Tera OhmsI am using only 50 Volts for this measurement, because I can not find my interlock adapter for the 2450.Next to do:- Install PT100 and Type-K temperature sensors- Install magnetic switch for interlock.

author: texaspyro
author_rank: Super Contributor
timestamp: August 27, 2017, 05:41:30 pm
content: Quote from: HighVoltage on August 27, 2017, 04:28:41 pmUsing adhesive tape anywhere remotely near a high impedance device is a VERY bad idea. Tape has a very high stored electrical charge. As part of the manufacturing process they zap the stuff with what amounts to a Tesla coil and it produces what amounts to an electret.You can generate fairly strong (medically useful) x-rays by uncoiling a roll of tape in a vacuum chamber. I have a couple of 3M static field testers that you calibrate using a piece of adhesive tape... these testers use a tritium source to provide ionization.

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: August 27, 2017, 05:55:17 pm
content: Thanks for showing your ideas and results. I am starting a teardown repair on a Keithley 6517 and was considering a similar design. The only change I was going to make was a guarded plate or box. I did something similar with a 1G resistor with a box within a box mounted to a sheet of PTFE. It was stable when moving my hands nearby.Since you added 2mm connections for the guard ring, do you plan on adding a guard to reduce leakage?

author: Vtile
author_rank: Super Contributor
timestamp: August 27, 2017, 06:32:46 pm
content: Really nice... Those small and cheap "safeboxes" might also act as a good starting point of these kind of chambers.Are you sure it the box is leaking while you touching it. Not the Triax cable or ground drifting from induced emf. I can measure up to about 10 volts (I assume even more) of stray AC voltage from my finger with my modest 100meg (DC .. AC is something less 10 megs iirc ) needle movement (with mains power or from floating battery operation) at my workbench with all sorts of household appliances running in poor day. I can also measure with the same meter my own movement (meter upwind) in my "wilderness" fishing cabin (no electricity network in about 5 km radius) from over 2 meters distance. The wind itself is makes the needle move a few millivolts DC (read with binoculars from 15 meters away). In there the AC range gives zero no matter what I try.Edit1.Under the powerlines 110kV I assume, I can measure 75Vac at the level of my head and 3 uA current to ground, with totally unscientific method just turning the meter on. Low freq. EMF litter everywhere in urban environments.Edit2. Also that melamine coating of the lab table is like propably also a really good generator of troubles.

author: plesa
author_rank: Frequent Contributor
timestamp: August 27, 2017, 08:03:08 pm
content: Nice box! BTW why did you choose B2987A instead of 6517B?Also interested in tear-down, I can post some internal photos of 6517B, but not internal pictures of input stage, sorry, too sensitive

author: HighVoltage
author_rank: Super Contributor
timestamp: August 27, 2017, 08:58:20 pm
content: Quote from: texaspyro on August 27, 2017, 05:41:30 pmOK, I must admit, that I have not even thought in this direction, since one side of the electric tape is "grounded" to the metallic box.If there will be residual charge, I should be able to measure it in the nano volt range between the box as a ground and the 4 different PTFE plates, right?Very interesting and thanks for pointing this out.

author: HighVoltage
author_rank: Super Contributor
timestamp: August 27, 2017, 09:03:01 pm
content: Quote from: ManateeMafia on August 27, 2017, 05:55:17 pmYes, this was one of the thoughts I had for the next improvement.I also wanted to place my high ohm resistors in in a separate small aluminum box with 2 mm banana plug receptors.Please show us the inside of your 6517 repair.

author: HighVoltage
author_rank: Super Contributor
timestamp: August 27, 2017, 09:06:27 pm
content: Quote from: Vtile on August 27, 2017, 06:32:46 pmInteresting thoughts indeed.I will further investigate.

author: Vtile
author_rank: Super Contributor
timestamp: August 27, 2017, 09:08:19 pm
content: Quote from: HighVoltage on August 27, 2017, 09:06:27 pmNote that I'm noob. So it is only rather uneducated guesswork.As an one example of electrically charged membranes:http://www.sciencedirect.com/science/article/pii/S0924424799002691

author: plesa
author_rank: Frequent Contributor
timestamp: August 27, 2017, 09:10:53 pm
content: Quote from: HighVoltage on August 27, 2017, 08:58:20 pmIn your case it should be not big deal, I suppose, because it is between insulation and ground. If you needs to make sensitive measurement create quard box inside insulated by PTFE.

author: plesa
author_rank: Frequent Contributor
timestamp: August 27, 2017, 09:12:54 pm
content: Quote from: ManateeMafia on August 27, 2017, 05:55:17 pmWhat failed in 6517? I saw one unit on ebay which does not power on.

author: HighVoltage
author_rank: Super Contributor
timestamp: August 27, 2017, 09:17:44 pm
content: Quote from: plesa on August 27, 2017, 08:03:08 pmAfter many weeks of looking at both units in detail, the Keithley 6517 and the Keysight B2987A, I decided in favor of the B2987A because:1. Statistical analysis directly at the display2. Integration of the instrument in to BenchVueThe Keithley 6517 intrigued me a lot, I must say and I was almost at the edge of buying one.Yes, please show us some tear down pictures.I will probably open up the B2987A but feel the same as you about the input stage, although that would probably be the most interesting part.Plus, I am not sure if the unit will have the Keysight calibration seals over the screws.

author: plesa
author_rank: Frequent Contributor
timestamp: August 27, 2017, 10:00:53 pm
content: Quote from: HighVoltage on August 27, 2017, 09:17:44 pmI have the same dilemma and decided to buy 6517BAt the end the input bias decided. Keysigh sent me B2987A for three weeks and I found quite difficult to use everything from remote panel.In my setup I'm using Python and Raspberry, so statistic in menu and BenchVue is not added value for me. BTW 6517 is integrated into KickStart SW.

author: razberik
author_rank: Frequent Contributor
timestamp: August 27, 2017, 10:23:47 pm
content: Dont be afraid and be a hero ! Open that input stage.

author: plesa
author_rank: Frequent Contributor
timestamp: August 27, 2017, 10:31:13 pm
content: Quote from: razberik on August 27, 2017, 10:23:47 pmHero != dumbI found the two SMD capacitor near by enclosure seems to be over-pressurized. SO warranty can apply soon

author: razberik
author_rank: Frequent Contributor
timestamp: August 27, 2017, 10:52:24 pm
content: What a pity.Is that shield cover soldered to board ? I would open it anyway. I don't think that opening it would screw it if I follow sensitive rules and precautions.There are A version internal photos on xDevs and nothing special there. Few resistors, capacitors, relays and some semiconductors.

author: plesa
author_rank: Frequent Contributor
timestamp: August 27, 2017, 11:01:06 pm
content: Quote from: razberik on August 27, 2017, 10:52:24 pmThere is Kapton tape only. It is not soldered. I'm familiar with 6517A units there is cover similar to cover in K6485.

author: HighVoltage
author_rank: Super Contributor
timestamp: August 28, 2017, 12:01:02 am
content: Quote from: plesa on August 27, 2017, 10:00:53 pmWhat about the input bias of the 6517B did you like better to make this decision?QuoteThat one I missed! Thanks for pointing it out.It would be nice to have both instruments next to each other for a real comparison.

author: HighVoltage
author_rank: Super Contributor
timestamp: August 28, 2017, 04:15:06 pm
content: I just came across this nice video by Keithley, explaining that Teflon (PTFE) indeed is a good choice for the insulation in such a shielded box.Watch the video to the end.

author: HighVoltage
author_rank: Super Contributor
timestamp: August 28, 2017, 04:55:12 pm
content: Today I build a little aluminum box for the 1 Tera-Ohm resistor with a connector to guard the resistor box.What a difference!Suddenly the value measured is very stable!Here are the first pictures:

author: HighVoltage
author_rank: Super Contributor
timestamp: August 28, 2017, 05:04:21 pm
content: It seems with these settings and 50V Source Voltage, the final value settles after about 10 min to 992 GOhm.

author: plesa
author_rank: Frequent Contributor
timestamp: August 28, 2017, 08:18:08 pm
content: The input bias current is on Keithley 3fA and on Keysight 20fA. The price is same.Try to contact Keithley they should have demo unit.In your box I will replace the banana socket or place them in insulator like PTFE. The banana insulation can affect the measurement.just try it.And thanks for video, this is the low measurement hack video with alu box, which I was looking for for long time:)

author: HighVoltage
author_rank: Super Contributor
timestamp: August 29, 2017, 03:10:56 pm
content: Quote from: plesa on August 28, 2017, 08:18:08 pmOK, good advise.I ordered some Teflon material to make insulators for the 2mm sockets.Today the same 1TOhm resistor settles at a little higher value.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: August 29, 2017, 05:50:04 pm
content: Not sure if it matters, but there are some differences between virgin Teflon and "mechanical" grade Teflon, which contains some recycled material. Hopefully the vendor is clear on what they're supplying. Teflon is the bee's knees, but I've also used polypropylene for insulators to good effect.

author: HighVoltage
author_rank: Super Contributor
timestamp: August 30, 2017, 10:59:39 am
content: Quote from: Conrad Hoffman on August 29, 2017, 05:50:04 pmYes, that is a good point for some young players.I had some good experience in using PTFE over the years for high voltage applications.And at one time, the PTFE was so conductive, that nothing worked.I also had bought some "conductive" polypropylene many years ago.Best to check first.These days I use medical grade PTFE for all my high voltage applications and now also for this insulator.

author: HighVoltage
author_rank: Super Contributor
timestamp: August 30, 2017, 11:03:27 am
content: Today is the third day in follow that I have been measuring this very same 1 Tera Ohm resistor.And every day the graph looks a little different.I wonder why.Humidity and temperature has been the same all all three days.My turn on procedure has been the same.May be it is a residual charge of sort, that was left in the resistor, when it was turned off yesterday?Here are the pictures from all three days in a row.All three have 50 Volt source voltage

author: 4CX35000
author_rank: Regular Contributor
timestamp: August 30, 2017, 11:35:14 am
content: It will be slight thermal variations that you are noticing, but probably within the specification of the resistor. Look at the datasheet for thermal characteristics.I have seen similar variation on my old Keithley 617. In my case it variation was within the limits of the resistor I'm using.What resistor are you using ?

author: HighVoltage
author_rank: Super Contributor
timestamp: September 05, 2017, 04:48:40 pm
content: Quote from: 4CX35000 on August 30, 2017, 11:35:14 amI am using a Russian military resistor, like in the following picture.

author: HighVoltage
author_rank: Super Contributor
timestamp: September 05, 2017, 04:58:41 pm
content: My Keysight B2987A Electrometer arrived today.I thought I will do a quick measurement, but it seems the learning curve is a little steeper then expected.So, I guess it will be a while before I will open the instrument up.

author: plesa
author_rank: Frequent Contributor
timestamp: September 05, 2017, 07:39:10 pm
content: I do not want to bias you. I have same experience. Menu is not too intuitive.

author: HighVoltage
author_rank: Super Contributor
timestamp: July 18, 2018, 06:37:06 pm
content: shodan@micronNice shielded box you have built.I got the very same E+E sensor as well, just have not mounted it.And yes, even after a while of usage, the Keysight B2987A is horrible.But it can be easily controlled by remote software.What is it that you want to measure, when you are done?

author: Berni
author_rank: Super Contributor
timestamp: July 18, 2018, 07:21:52 pm
content: I just came across this thread and does it sure have some electrometer porn in it.I had a plan to build a box of my own but never finished it. However i resorted to using XLR on the other end due to triax being so ridiculously expensive. The cables i ended up using for my HP 4041B SMU are actually twinax rather than triax as i could get a bunch of them on the cheap to fill out the 5 channels on that instrument. But that works just as well since the pinout goes: center sense, middle force, outer guard. And yes this means grabbing the outer metal body of the triax can give you a 100V shock.My Keithley 617 Electrometers had the additional challenge of having the 2 lug triax plug. Has taken me quite a while to find one on ebay for a reasonable price.But im doing all this on the cheap. You guys probably have cables that cost more than my whole setup.

author: plesa
author_rank: Frequent Contributor
timestamp: July 19, 2018, 06:28:09 pm
content: Quote from: HighVoltage on July 18, 2018, 06:37:06 pmUnfortunately, I can confirm it

author: HighVoltage
author_rank: Super Contributor
timestamp: July 19, 2018, 06:53:37 pm
content: Quote from: shodan@micron on July 18, 2018, 06:46:43 pmNice, keep us posted with some pictures, of how it works out.Quote from: Berni on July 18, 2018, 07:21:52 pmIf you look long enough on ebay and other places, good deals can be found.But in general, these parts are ultra expensive.Buying full length cables and cut them in half to make some adaptersalso safes some money.Quote from: plesa on July 19, 2018, 06:28:09 pmI think the day will come that I will sell the Keysight B2987A and get a new Keithley 6517B instead.

author: plesa
author_rank: Frequent Contributor
timestamp: July 19, 2018, 07:18:28 pm
content: Quote from: plesa on July 19, 2018, 06:28:09 pmI think the day will come that I will sell the Keysight B2987A and get a new Keithley 6517B instead.I have on my bench Keysight for 2 weeks or so and it was nightmare and purchased Keithley 6517B for same price. Before selling B2987A you can make teardown

author: HighVoltage
author_rank: Super Contributor
timestamp: July 19, 2018, 07:29:45 pm
content: Quote from: plesa on July 19, 2018, 07:18:28 pmOK, so at least I am not alone, thanks for your confirmation.The Keysight B2987A on paper specs looks so great but in real life it is so different.I should have borrowed one before I bought it.Ok, I will make a teardown of the B2987A before I sell it.

author: Zucca
author_rank: Unknown
timestamp: July 20, 2018, 06:40:23 am
content: Quote from: Berni on July 18, 2018, 07:21:52 pmSorry for bombing in the thread,FYI I am selling some decent triax cocaine with a K220:https://www.eevblog.com/forum/buysellwanted/zucca-sales-(d)-keithley-220/- Triax Cable Keithley 237-ALG-2- POMONA 5299 adapter Triax F zu BNC M,- Triax Cable Keithley 7078-TRX-10.- Triax Cable grey, I think it is Agilent- Calibration Fixture as described in the 220 Service Manual page 5-2.

author: Berni
author_rank: Super Contributor
timestamp: July 20, 2018, 10:39:35 am
content: Nice collection of stuff you are selling there and even close to me, tho the price is still a bit steep for me given how much I use this stuff.And yes I did cut triax cables in half to save cost. 5 triax to triax cables and 5 panel mount triax connectors I don't even want to know how much it would cost. Even nice XLRs are cheaper and they work well enough in my experience.

author: Zucca
author_rank: Unknown
timestamp: July 20, 2018, 10:43:16 am
content: First rule buy only what you need, don't do like me

author: Echo88
author_rank: Frequent Contributor
timestamp: July 20, 2018, 11:05:25 am
content: If we would only buy what we need this forum-section wouldnt exist.

author: HighVoltage
author_rank: Super Contributor
timestamp: July 20, 2018, 02:44:25 pm
content: I am glad to buy more than I need, because eventually I will need it.ZuccaThat is a nice collection of TRIAX cables.I am surprised it is not sold!

author: Berni
author_rank: Super Contributor
timestamp: July 21, 2018, 06:26:51 am
content: Quote from: zucca on July 20, 2018, 10:43:16 amLooking at the U42 rack and bench shelve full to the brim with equipment...yeah that's exactly what I was doingI would ask for the triax bits seperately if my electrometer didn't have the dreaded 2 lug Triax connector on it.

author: plesa
author_rank: Frequent Contributor
timestamp: July 22, 2018, 09:27:53 am
content: Quote from: shodan@micron on July 22, 2018, 06:54:12 amFor this price you can have real low noise triax. Belden ones are not low noise.The used connectors are also not suitable for low current measurementsCheck thishttps://www.ebay.com/itm/KEITHLEY-7078-TRX-3-3-SLOT-TRIAX-CABLE/273100148716?https://www.ebay.com/itm/LOW-NOISE-TRIAX-CABLE-7078-TRX-5-for-Keithley-236-237-238/331810119121?

author: ch_scr
author_rank: Frequent Contributor
timestamp: July 26, 2018, 08:10:45 pm
content: shodan@micron, the Keithley Triax is indeed different. I got some surplus Triax connectors from ebay that fit the more conventional "Keysight" Style with ease (i have an old HP Test fixture) - but on my Keithley 2636, they are very hard to push in. Hard enough that it almost feels like damaging it, definitely increased wear. I would really like to know where to get those Keithley-Style connectors to make my own Cables. The connectors that came on my Keithley cable have no part number on it.

author: TiN
author_rank: Super Contributor
timestamp: July 27, 2018, 04:06:08 am
content: These are high-voltage triaxes, common for parametric analyzers (can go up to 2kV).

author: HighVoltage
author_rank: Super Contributor
timestamp: July 27, 2018, 09:55:18 am
content: And the high voltage triax connectors are NOT compatible to the "normal" triax connectors.And usually they are much more expensive.

author: HighVoltage
author_rank: Super Contributor
timestamp: July 29, 2018, 04:38:18 pm
content: Quote from: shodan@micron on July 27, 2018, 10:10:59 amThe Triax connectors on my Keysight B2987A and my Keithley 2450 are the same.I finally bought a Keithley 6517B, it should arrive soon.Then I can do a real comparison between the 6517B and the B2987A and the source meter 2450

author: HighVoltage
author_rank: Super Contributor
timestamp: July 29, 2018, 06:37:19 pm
content: I will take some pictures and measurements tomorrow on the instruments I have at hand.

author: HighVoltage
author_rank: Super Contributor
timestamp: July 31, 2018, 05:18:27 pm
content: OK, I made some measurementsKeithley 2450 SMU- Outside: 9.63 mm- Inside: 8.16 mm- Inside inner shield: 4.39 mm- Depth to inner shield: 3.38 mm- Depth to inner insulator: 4.65 mmKeysight B2987A- Outside: 9.50 mm- Inside: 8.28 mm- Inside inner shield: 4.28 mm- Depth to inner shield: 3.46 mm- Depth to inner insulator: 3.57 mmCHINCH Trompeter BJ770- Outside: 9.68 mm- Inside: 8.25 mm- Inside inner shield: 4.50 mm- Depth to inner shield: 3.31 mm- Depth to inner insulator: 3.24 mmKeithley T-Connector- Outside: 9.68 mm- Inside: 8.30 mm- Inside inner shield: 4.37 mm- Depth to inner shield: 3.17 mm- Depth to inner insulator: 3.37 mmY-Adapter TN2A (metrology grade)- Outside: 9.70 mm- Inside: 8.22 mm- Inside inner shield: 4.39 mm- Depth to inner shield: 2.94 mm- Depth to inner insulator: 2.91 mm

author: HighVoltage
author_rank: Super Contributor
timestamp: July 31, 2018, 05:27:09 pm
content: Of the many original Keithley cables I have,most of them are marked7078-TRX-3but two cables are marked7072-DI can not detect a difference in these Keithley cables.They fit all my Triax connectors well.

author: TiN
author_rank: Super Contributor
timestamp: July 31, 2018, 07:21:07 pm
content: QuoteD stands for dirty.

author: Brad O
author_rank: Regular Contributor
timestamp: August 01, 2018, 09:14:40 pm
content: For the Keithley cables, 7078-TRX is the name of the cable itself, the 3rd number is the length designation as you probably guessed. 7072 is a switch card that uses 7078-TRX cables, so some of HighVoltage's cables must've originally accompanied that card. Besides a few special exceptions, all Keithley instruments that use triax will use this cable, the cable design goes back almost as far as triax itself.The connectors on the 7078-TRX cables have their own part numbers and can vary, usually it's a CS-631 3-slot male connector. Here's the closest thing to a datasheet I could easily find, it has and a few specs and an interesting blow-up diagram of the connector:https://www.tek.com/manual/model-cs-631-3-lug-cable-mount-triax-connector-users-guide-manual. I'm not sure of the details on the 2-lug versions of 7078-TRX cables, but I can search around here more if anyone wants.The female connector for the CS-631 has the part number CS-630 and has two different bulkhead connector styles, 237-TRX-TBC (usually for high voltage applications, the other side is a coax cable mount) and 7078-TRX-TBC (The more common one for fixtures with ready to solder pins on the other side). As I just learned, TBC stands for Triax Bulkhead Connector, just a fun bit of trivia for ya.Not as helpful in terms of specs, but this doc has descriptions, pictures, and part numbers for all the Keithley connectors I mentioned:https://www.tek.com/datasheet/connectors-adapters-and-tools/connectors-adapters-and-tools

author: HighVoltage
author_rank: Super Contributor
timestamp: August 02, 2018, 12:00:38 pm
content: Quote from: Brad O on August 01, 2018, 09:14:40 pmBrad OThank you, for the very good information...And yes, if you find any info on the older 2-lug versions, please share them with us.I still have a few older Keithley instruments with 2-lug terminals.Since I started with my Triax box, I have tested many different cablesand came to the conclusion, that the original Keithley cables are the best so far.They are metrology grade it seems and worth their price.

author: Brad O
author_rank: Regular Contributor
timestamp: August 02, 2018, 03:32:29 pm
content: Well here's a whole bunch of part numbers for the 2-lug versions of the Keithley triax cables. I don't know how much luck you'd have trying to find any of these, but if you can find these parts you could make your own cables.7024 cables are the 2-slot male triax cables, the 2-slot connector itself has the part number CS-141. 7023 is the product number for the female bulkhead connector, its part number is CS-440. The model 617 originally came with a 6011 cable that's the same as the 7024 cable but has one end terminating in alligator clips.The 7024 and 7078 cables both use the same raw cable (I was wrong earlier when I said the 7078 is the name of the cable itself, it's the product number for the 3-slot version). The raw cable has the part number SC-22. Here's a datasheet I found on it, sorry it's a direct download link:https://forum.tek.com/download/file.php?id=24731These cables have graphite insulation to help make them low noise, but they're not the lowest noise triax cable Keithley uses, I *think* that title belongs to the 4200 and 4200A triax cables that use cable with the part number CS-181, they have a tighter weave and are held to closer specs, but they're also only rated to 250V (They're calledUltraLow Noise Triax Cables).This might also be helpful to you, the 6172 (P/N CS-500) adapter is used to connect 3-slot triax cables to 2-lug triax connectors, so finding one of those might be cheaper in the long run than buying whole separate cables for your 2-lug triax instruments. The 6171 (P/N CS-505) adapter goes the other way.I'm uploading an old catalog of Keithley connectors (circa 2003) and here's an old catalog of cables that gives part numbers on page 3:http://farnell.com//datasheets/1993899.pdf

author: LapTop006
author_rank: Unknown
timestamp: September 07, 2018, 06:22:16 am
content: Quote from: Brad O on August 02, 2018, 03:32:29 pmI'm tempted to ask for a quote on the invisible USB cable on the last page.

author: HighVoltage
author_rank: Super Contributor
timestamp: September 07, 2018, 08:44:18 am
content: Quote from: shodan@micron on September 07, 2018, 05:53:02 amThat looks very nice.How about a safety switch for lid, so the 1000V would not stay life, when the lid is removed?I got the same humidity sensor but have not integrated it in to my box.Your integration of the sensor looks very nice!

author: Doege
author_rank: Newbie
timestamp: September 18, 2018, 07:12:45 am
content: I am doing a similar setup, and I cannot ID the connector on the instrument. To make it worse I do not even have access to the instrument at this time, only pictures. As the parts are quite expensive, I hope to get the connector IDd by someone knowledgeable. Please have a look at this stack exchange question where I have the pictures:https://electronics.stackexchange.com/questions/396471/unknown-triax-connectorThank you for your time, and sorry for posting in this thread. It just seemed like I can reach the correct people and this is very recent thread too.

author: Berni
author_rank: Super Contributor
timestamp: September 18, 2018, 07:43:15 am
content: Now now THAT is an evil looking connector. To me it looks like a TNC version of triax.But you can often find some very obscure cables on ebay if you look for long enough (Problem is that they often don't have the right name in the title because the seller has no idea what the cable even is)

author: Brad O
author_rank: Regular Contributor
timestamp: September 18, 2018, 01:55:29 pm
content: That's an RF triax cable for high frequencies, wow, you really don't see them very much.The female connector on the instrument is P/N 1250-2228, I couldn't find one for just the male connector, looks like Keysight only sells the whole cable. Here's the service manual for the instrument:http://literature.cdn.keysight.com/litweb/pdf/04339-90043.pdfand the test fixture:https://literature.cdn.keysight.com/litweb/pdf/16117-90041.pdf?id=689310(I think the male connector is included in P/N 16117-61604, "Cable Assembly (triaxial)")

author: HighVoltage
author_rank: Super Contributor
timestamp: September 18, 2018, 02:42:32 pm
content: I saw one of these connectors on an old HP adapter with lots of cables on ebay.Good to know, it is a RF Triax connector!

author: Doege
author_rank: Newbie
timestamp: September 19, 2018, 07:09:54 am
content: Quote from: Brad O on September 18, 2018, 01:55:29 pmThanks, I have now done search with those part numbers. Since the instrument and accessories for it are discontinued these cable assemblies can only be bought second had.But you gave me new hope by naming it "RF triax cable for high frequencies". I will search for that as well, before I result in desperate measures and buy a cable assembly. It's a sin to cannibalize already rare item to get the adapter so I'll try to avoid that.Thanks everyone!

author: syau
author_rank: Frequent Contributor
timestamp: September 25, 2018, 11:34:35 am
content: The Triax BNC connector used in the MIL-STD-1553B may be another optionhttps://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com.hk%2Fulk%2Fitm%2F263335577143

author: Doege
author_rank: Newbie
timestamp: October 08, 2018, 06:30:48 am
content: Quote from: syau on September 25, 2018, 11:34:35 amI found this company who makes drop-in replacements for 4339 accessories.https://www.skgautomation.com/agilent-4339b.html

author: HighVoltage
author_rank: Super Contributor
timestamp: October 26, 2018, 10:17:34 am
content: Very interesting comparison between the two instruments.I will repeat your test, to see if I get the same artefacts at 21V and 35.8VI now have a Keithley 6517B as well and just got all the original connectorsfrom Tektronix for the back of the instrument.BTW, you have nice lab pictures on your Instagram account.

author: coppercone2
author_rank: Super Contributor
timestamp: October 28, 2018, 04:39:23 am
content: I wonder if you can polish PTFE to have a smoother surface and retain less crap and clean easier. On the other hand its soft and its going to possibly embed the lapping material.It does look like your box fits together very poorly though. Why did you decide not to square up the edges?How did you cut the material?Other suggestions :Add strain relief to the solder joints.Don't just wipe the surface. After you wipe it, hold the box upside down and rinse it with methanol from a squirt bottle.Actually, why even have teflon on the walls?It would seem like using a bigger piece with the circuit in the middle would work better then the walls because its easier to cleanand I thought you were supposed to use cotton gloves for this to avoid anything coming out of the rubber ones (i.e. put cotton over the latex).

author: coppercone2
author_rank: Super Contributor
timestamp: October 28, 2018, 06:49:27 am
content: I don't know if latex uses any kind of additive or has any materials which leach out of it when its stretched. I think they are meant for health purity not electrical purity.But for the cleaning I mean, if you put methanol on a wipe, and wipe something down, all you do is dilute it (same if you soak it in a tub). You want to run fresh methanol over the whole thing and throw away the washings so your not just diluting the grease naturally (or not so much) found in air.Same for prepping stuff for plating etc, you can soak it and wipe it down first to mechanically stir things up and remove the bulk of the contaminate, but you wanna squirt fresh solvent on it and let it drip off for the final clean, then let it air dry. Think of a soxhlet extractor.Or, when you wash dishes. You don't just soak the dishes in soap water or use a towel on em then put it in the drying rack, you rinse them under running water to make sure all the soap, oil, etc is gone after you scrub them.https://www.jokertattoo.net/images/H1003-13%20500ml%20new.jpgIdeally you would want plasma cleaned sapphire I think. Not sure if you can plasma clean teflon.

author: coppercone2
author_rank: Super Contributor
timestamp: October 28, 2018, 07:00:47 am
content: you might actually be slightly dissolving the gloves with very pure methanol (its kind of an aggressive solvent). Latex is natural after all. Not sure if you can use a mixture of methanol/super pure water to clean the surface a bit but not attack them to possibly let more stuff out. Not sure if plastic/vinyl/etc are any better because they probably use plasticizes.Really not sure, you would something like a gas chromatograph to detect such small changes. Might be non issue, but I swear I read some where (maybe keithley) that they recommend clean cotton gloves, perhaps with a specific weave/fiber type.You are not really worried about particles falling down (since you can blow them off) but more like oils.:easy solution:use ceramic tweezers and ceramic tools which you can heat past 400C for cleaning to remove all oils. Ceramic tweezers are really nice, you can hold them in a direct jet-flame for a while, till the soot burns off.. defiantly no oil or organic molecule left there. When I cleaned some high-z stuff I made, I used high purity diethyl ether for cleaning. High purity methanol might be better but I think its a more aggressive solvent and its also toxic, so I prefer to use ether because it metabolizes into ethanol. I believe methanol is carcinogenic I don't want to breath that crap if I don't have to.

author: coppercone2
author_rank: Super Contributor
timestamp: October 28, 2018, 07:16:17 am
content: if you use compressed air to clean it, the way I measured my air or gas purity, at least to get an indicator without complicated things, is to attach your gas flow to a PVC tube so there is significant flow and no back-wash or diffusion, then put one of those e-bay humidity/temperature probes in there (usually meant for HVAC use), then measure the dew point, you can see what standard your air falls into based on the dew point using industrial guides.You will probably be disappointed by most compressors, so I recommend getting a small nitrogen tank from the welding store. They are used for filling pipes or fuel tanks etc with nitrogen when you are doing brazing or soldering, so you don't get red-hot metal exposed to air making corrosion on the inside. They also sell special adapters for routing the gas into pipe networks.The manual says 'nitrogen gas' because they KNOW facilities air is typically garbage. You can also buy clean dry air in a cylinder but the problem is, for nitrogen you can get the small sized tank, some welding suppliers will only sell you the air if you RENT a tank that is as tall as you, because no one wants to buy small tanks of air typically. But plenty of people buy small nitrogen tanks.Small air tank is still kind of useful though if you have compressed air tools and you need to do a quick job like use a small nail gun inside of the house to fix something etc. Eventually I will buy one.Big one is even more useful though, because you can properly run a plasma cutter on it. I ran my plasma cutter on nitrogen but without the oxygen content it does not do as good a job cutting regular steel (good for stainless or some shit tho). The little electrodes wear less when you use proper air, rather then the humid compressor shit. It's also fairly quiet compared to a compressor fucking off on you and going BRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR enough to wake the local dead.

author: HighVoltage
author_rank: Super Contributor
timestamp: October 29, 2018, 08:19:14 am
content: I totally agree,For anything metrology gear pressure cleaning, I always use compressed nitrogen from a bottle.Even if you have an oil and water filter in line with compressed air from an air compressor, it is never clean enough.

author: Brad O
author_rank: Regular Contributor
timestamp: October 29, 2018, 05:22:26 pm
content: Quote from: shodan@micron on October 25, 2018, 11:00:19 pmThe artifact at 21V is almost certainly due to autoranging, I see another small blip at 2V that would be the same thing. The blip at ~36V is a little more strange, but it could be something with the interlock. You may want to check your protection circuit to see if there's any room for a bad connection (especially if the protection circuit is just a wire).Quote from: shodan@micron on October 25, 2018, 11:00:19 pmThanks for the feedback, I'll pass this along to the engineers! Could you elaborate a little more on how you want CSV export to work though? Like is the process to complicated or something else? You can also reach the desginers directly by emailing kickstart at keithley.com, that address is also listed in the settings window.

author: Echo88
author_rank: Frequent Contributor
timestamp: November 07, 2018, 10:24:06 am
content: I want to test and use a few foil caps (KEMET C4AEhttps://www.mouser.com/ds/2/212/KEM_F3046_C4AE_RADIAL-1107630.pdf, WIMA MKS4https://www.wima.de/wp-content/uploads/media/d_WIMA_MKS_4.pdf).What are the recommended alcohols/solvents to clean the foil-caps to get rid of debris/skin-oil, without affecting the plastic-casing?

author: HighVoltage
author_rank: Super Contributor
timestamp: June 26, 2019, 09:06:36 am
content: Quote from: shodan@micron on June 26, 2019, 08:41:09 amGreat suggestions.I had noticed this as well and when I don't use the electrometer as a source, I disconnect the cables completely.So far I had not tried to set the output to 0 and turn the output on.Good point, I will try that.

author: TiN
author_rank: Super Contributor
timestamp: April 14, 2020, 06:16:24 am
content: Strange connection, I'd expect guard to be tied to the enclosure, so leakages and charge from enclusure are isolated from sensitive nodes inside. Guess you did that to avoid building more traditional box in a box construction?

author: HighVoltage
author_rank: Super Contributor
timestamp: April 14, 2020, 03:24:44 pm
content: How stable are your resistor measurement results ?I am working on a new shielded box with another shielded box in the box.

author: TiN
author_rank: Super Contributor
timestamp: April 15, 2020, 01:05:06 am
content: Reminds my previous failed project 2 years ago.While it worked somewhat decent up to 10 GOhm higher values (100G, 1T, 4T) were changing output just from thinking about it

author: KeepItSimpleStupid
author_rank: Regular Contributor
timestamp: April 15, 2020, 11:31:34 am
content: i don't see any guard plates.The outside case should be ground.Then you need guard. This generally connects to the inner shield. It should be driven with the same voltage as the inner conductor.Now something insulating that doesn't have a lot of capacitance.Device goes on top of that insulated and guarded plate.Keithley Triax cables have layer of graphite to reduce the triboelectric effect.You have to somewhat watch out for the piezoelectric effect. i.e. Squishing the Teflon/PTFE.System should not be subject to vibration.

author: TiN
author_rank: Super Contributor
timestamp: May 27, 2020, 03:40:32 am
content: My eyes all broken trying to count zeroes on current scaleJust use engineering notation, readers will say thank you..Or you could recalculate resistance already for the graph.Quote

author: TiN
author_rank: Super Contributor
timestamp: May 27, 2020, 04:56:55 am
content: All good deeds are punishable, I suppose.Suggesting better representation got me to ignore list, that's newEspecially funny howshodan@microndidn't mind to reuse my graph code script though.

author: coppercone2
author_rank: Super Contributor
timestamp: May 27, 2020, 06:06:36 am
content: Quote from: TiN on May 27, 2020, 04:56:55 ampicking a fight over nothing after code was modified is suspect, not to mention pointing out incompetence, as if it was not initially usefuli think someone here has some financial aspirations, sounds like co worker

author: HighVoltage
author_rank: Super Contributor
timestamp: May 27, 2020, 08:14:05 am
content: Nice setup, shodan@micron.You might want to use pure copper crocodile clips

author: bsw_m
author_rank: Frequent Contributor
timestamp: October 20, 2020, 09:22:54 am
content: Quote from: HighVoltage on December 03, 2016, 04:23:32 pmPlease consider the following.Any insulating material can generates and stores a charge. Stacking PTFE sheets in an ultra-low current meter box can have many undesirable effects.In my humble opinion, the measuring box for ultra-low currents should be all-metal without additional insulating materials.

author: HighVoltage
author_rank: Super Contributor
timestamp: May 07, 2021, 03:14:36 pm
content: Quote from: shodan@micron on May 06, 2021, 06:49:23 pmNice resistor!What is the part number?

author: HighVoltage
author_rank: Super Contributor
timestamp: May 07, 2021, 07:03:16 pm
content: Oh, that resistor RX-1M5009KE has 10% tolerance, I was hoping for better.Looking forward to your measurements, I will order one as well.

author: Melaa
author_rank: Newbie
timestamp: May 08, 2021, 05:01:08 pm
content: Do you have a microscope? Maybe there are cracks in the glass?What was the humidity when you measured resistor?I think its manufacturing defect.

author: HighVoltage
author_rank: Super Contributor
timestamp: May 08, 2021, 05:08:08 pm
content: The stated TC of the datasheet is50 ppm/°CYours is 12 fold higher, this must be a manufacturing defect.Ohmite usually is very reliable in their datasheets.I would claim a bad resistor and return it under warranty!

author: Bill_at_PEARL
author_rank: Newbie
timestamp: July 30, 2021, 11:37:28 pm
content: Wonderinf where to find a 2-lug triax input cable to fit a Keithle

author: Bill_at_PEARL
author_rank: Newbie
timestamp: July 30, 2021, 11:45:52 pm
content: That was supposed to read:"I'm wondering where to find a 2-lug triax input cable to fit a '70s vintage Keithley Model 153 Microvoltmeter/Ammeter. See the pic.TIA Bill"

author: HighVoltage
author_rank: Super Contributor
timestamp: July 31, 2021, 02:14:31 pm
content: You need to look on ebay or similar places for used cables.These cables are not easy to find.Or you can use a 2 lug to 3 lug converter and then use the 3 lug cables.

author: MiDi
author_rank: Frequent Contributor
timestamp: July 31, 2021, 05:06:07 pm
content: You could replace the 2 lug with a modern 3 lug as I did for a K617 EM.Cheap alternative is to file one lug.

author: HighVoltage
author_rank: Super Contributor
timestamp: August 03, 2021, 07:48:46 am
content: There was just one 2-Lug Triax cable sold on eBay Germany.Someone got lucky for Euro 70.2600-ALG-2Konfektioniertes Prüfkabel, Triaxialkabelhttps://www.ebay.de/itm/154545540559

author: RaymondMack
author_rank: Regular Contributor
timestamp: August 04, 2021, 07:27:51 pm
content: @HighVoltageThat's a three-lug cable. I have two just like it.@Bill_at_PEARLIt's easy to spot a two-lug cable by looking for a Specialty Connector Co. branded triax connector, smaller alligator clips and seeing stripped triax all the way to the red lead (with the outer jacket and braid removed). This way the HI lead is guarded up to the alligator clip. Though newer two-lug cables use either a separate piece of coax or triax, rather than a straight through connection to the HI lead. I think the older construction is better for leakage.I have two, two-lug to three-lug Keithley triaxial cables I made by trading connectors between a pair of two- and three-lug cables that I've been considering selling. They've been pretty useful to have, but since I bought a male two-lug to female three-lug adapter they are a bit extraneous now. After selling my 220 current source, the only other equipment with two-lug connections is my 617 electrometer and I primarily use it with an HP semiconductor test fixture rather than flying leads.I would really recommend getting a decent HP/Agilent or Keithley test fixture. Flying leads are okay if you need to test in circuit or more general work, but for component characterization they aren't very easy to work with.

author: ezeisel
author_rank: Newbie
timestamp: August 07, 2021, 07:02:14 pm
content: There is a Keithley 6011-10 cable for sale on ebayhttps://www.ebay.com/itm/Keithley-6011-10-Cable-10ft-Triax-with-Test-Clips-NEW-/264891819342I believe, but am not certain, that this one has a two-slot/lug triax bnc connector, so obviously verify that first if you consider buying one

author: RaymondMack
author_rank: Regular Contributor
timestamp: August 07, 2021, 09:42:16 pm
content: Wow 200 USD! Talk about overpriced. I paid around 80 USD each for my two-lug triaxial cables. If you can wait, good deals always come up. I remember seeing a whole bunch of Keithley two- and three-lug triax selling for 20 to 50 USD a few months back. They were pretty short cables though, maybe 2 to 5 feet long.Anyways, the 6011-x are two-lug cables. It's the same part shown in the 5th photo attached to my previous post. These are the newer designs, but the older cables work fine too.

author: HighVoltage
author_rank: Super Contributor
timestamp: August 08, 2021, 05:27:52 pm
content: @RaymondMackYou are correct, that 2600-ALG-2 is in fact a three lug cableAnd the 6011-x are two-lug cablesI also have a few of each.It is getting more difficult to find correct and good quality TRIAX cables on ebay.The eevblog forum is probably partially at fault for this and the prices are rising.The 2600-ALG-2 is still available from KeithleyAnd in Germany it is listed for Euro 382 plus VAThttps://www.calplus.de/keithley-2600-alg-2.html

author: justanothername
author_rank: Regular Contributor
timestamp: August 10, 2021, 08:36:15 am
content: It's a little off-topic now but:Pomona 4725 - 2 lug triax to 3 alligatorPomona 5342 - 3 lug triax to 3 alligatorreasonably priced and on stock everywhere.