Keithley 220 Output Triax connector Mod - Page 1
Forum section: electronics / testgear

author: Zucca
author_rank: Unknown
timestamp: February 22, 2014, 10:47:05 pm
content: Hi there,I want to solve the problem of the old 2-Lug Triax output connector on the Keithley 220.Here my solutions:1) AdapterBuy the adapter Keithley 6172.http://www.amazon.com/Keithley-2-Slot-3-Lug-Female-Adapter/dp/B00C2DV92Gabout $70 it is a lazy, boring and expensive action.2) Bild a Triax cable adapterYes this is would be the normal preferred one, but I have to find the old male triax 2 lag connector which is more than 70$ according to my research.3) Repalce the connector on the unit with a modern 3 lag oneI like it, on the unit there is also a lot of space.... see picture below:And those are the candidates on Digikey:http://www.digikey.com/product-search/en/connectors-interconnects/coaxial-connectors-rf/1443098?k=triax%20female%20panel&stock=1So far the only connector I found <$70 on stock ishttp://www.digikey.com/product-detail/en/5219/501-1312-ND/745098But I am concerned about the quality.... I don´t to lose all the perfection of my gear on a cheap bad quality connector.I mean this one is so expensive $170:http://www.digikey.com/product-detail/en/DK-621-0434-1S/A101183-ND/2486192and there is should be a reason for that.On top of that I am concerned to damage the graphite coating of the Keithley output cable with my iron.What you would do?Thanks!

author: robrenz
author_rank: Super Contributor
timestamp: February 22, 2014, 10:57:13 pm
content: $22.35 USAherePomona Electronics 5219

author: Zucca
author_rank: Unknown
timestamp: February 22, 2014, 11:01:27 pm
content: Thanks Robrenz, so do you think the Pomona 5219 (also posted in my original post) with 22.35$ will not ruin the output quality? Sorry but I have no experience with nano/pico amp currents.

author: robrenz
author_rank: Super Contributor
timestamp: February 23, 2014, 03:06:47 am
content: The 5219 is Teflon insulation and the 4388 at $61.75 is PTFE and hermetic sealed for 50 PSI pressure.The original connectors on the 220 are Teflon so there will be no difference using the 5219. Also the driven guard will basically eliminate leakage currents even if the insulation resistance was not optimum.

author: Zucca
author_rank: Unknown
timestamp: February 23, 2014, 03:36:56 am
content: Thanks Robrenz, sold.

author: Zucca
author_rank: Unknown
timestamp: February 23, 2014, 05:42:56 pm
content: Work in progress:1)2)3)4)5) Auch! Removing the stupid metal cylinder cost me a isolation damage between the guard and common (see red arrow, the guard is now exposed)Time for heat shrink...

author: SeanB
author_rank: Super Contributor
timestamp: February 23, 2014, 05:50:54 pm
content: Need PTFE heat shrink for there, not regular ones.Stupidly expensive but worth it.Looked on eBay and it is around $10 for it.http://www.ebay.com/itm/10MM-PTFE-TEFLON-HEAT-SHRINK-TUBING-TUBE-3FT-/330846934065?pt=LH_DefaultDomain_0&hash=item4d08039431First hit

author: plesa
author_rank: Frequent Contributor
timestamp: February 23, 2014, 06:08:44 pm
content: Replace the current one 2lug triax with 3lug triax, currently only the 3lug version is preffered. I saw lot of damaged 2lug with BNC cable.The graphite coating you will not damage, the Keithley cable on picture can be easily soldered. Just wear glowes and clean it with IPA a bake it.As a replacement of the PTFE heatshrink you can use the reqular PTFE hose, which is available in chemical lab stores.Keithley use it in their Triax to banana adaptor Keithley 2600-ALG-2 or 237-ALG.Send me PM message if did not find anything suitable I have about 20 pieces of 3lug triax connector (made for HP)

author: Zucca
author_rank: Unknown
timestamp: February 23, 2014, 06:48:01 pm
content: Thanks, already ordered the PTFE heat shrink.Now the Pomona 5219 supports a 0.05" MAX PANEL THICKNESS, guess what... the Keithley 220 is .063".

author: SeanB
author_rank: Super Contributor
timestamp: February 23, 2014, 06:58:28 pm
content: Milling cutter? Can you chase a thread insert into it so you do not actually need the nut. From the looks you do not have to go through the thick panel just the thinner one the socket is in.

author: Zucca
author_rank: Unknown
timestamp: February 23, 2014, 07:12:56 pm
content: Milling is too dirty for me...I see the Pomona 3580...http://www.pomonaelectronics.com/pdf/d3580_1_01.pdfwe double the price but it seems to fit, but I don´t see the 3 lugs at 120°. Some datasheets are against the human race.

author: don.r
author_rank: Frequent Contributor
timestamp: February 23, 2014, 07:20:35 pm
content: Quote from: zucca on February 23, 2014, 07:12:56 pm2 lug :http://www.amazon.com/Pomona-3580-Triaxial-Receptacle-Hermetically/dp/B00CJPTX34

author: Zucca
author_rank: Unknown
timestamp: February 23, 2014, 07:22:13 pm
content: Thanks don.r... I give up. PM sent to plesa.

author: robrenz
author_rank: Super Contributor
timestamp: February 23, 2014, 08:48:02 pm
content: Just use the 5219 and don't use the lock washer. Use Loctite 242 or similar thread locking liquid. the washer is about .013" anyhow so it will work fine.

author: Zucca
author_rank: Unknown
timestamp: February 24, 2014, 04:11:38 am
content: Very interesting those D holes (fromhttp://emersonconnectivity.com/OA_MEDIA/catalog/tromp_t24_catalog_mil_aero.pdf):The hole in the Keithley 1,61mm panel is 9,5x8,72 mm (D5).So the Pomona 5219 is also too big (.453"; .190", D4) ... go figure...This one:http://www.mouser.com/ProductDetail/Trompeter-Emerson-Connectivity-Solutions/BJ157/?qs=sGAEpiMZZMukCeVMgJHkjFN%252byJ8Fu4C5bfdAxGAckzk%3dhttp://emersonconnectivity.com/OA_MEDIA/drawings/dr-BJ157.pdfis cool (D6 but I mean at this point I can live with that) but I don´t see the magic word Teflon, but it is 500MHZ as the Pomona. It should be not so far away, here more details:$17.12! Beauty!EDIT: DO NOT BUY IT. THE Trompeter-Emerson BJ157 IS TOO SMALL.

author: robrenz
author_rank: Super Contributor
timestamp: February 24, 2014, 12:27:57 pm
content: Good job finding that it looks good

author: rastro
author_rank: Frequent Contributor
timestamp: March 01, 2014, 03:34:14 am
content: Hello zucca,Thanks for sharing the details on the 220 triax connector upgrade. The connector on my unit is in poor shape and I will probably have to do the same. I was hoping to get some clarification on the coaxial cable before starting.Based on previous pictures 1 & 5 the cable that runs from the analog PCB to the triax bulkhead connector has three conducting layers. It appears that only two of these, the outer silver shield and the center conductor, is soldered to the triax connector. I do not see where the copper colored braided shield is connected to either the triax connector or the banana jacks.Would you confirm my assumption that the copper shield is not used on the output connectors? Or have I missed something?Cable from Analog PCB Triax Output Connector (fig 2-2 manual)------------------------ -------------------------------Exterior Black Insulator Chassis Common (Outer Triax Shield)Silver Braided shield * --------> Output Common (Inner Triax Shield)Insulation (Clear)Copper Braided ShieldInsulation (Clear)Silver Center Conductor -------> Output HI (Center Triax Condutor)*note: addition wire jumper goes to black banana jack labeled "output common".Thanksrastro

author: Zucca
author_rank: Unknown
timestamp: March 01, 2014, 08:41:56 pm
content: Hey rastro,Yes you are correct, but since we strive for perfection let´s look at the manual page to understand better the situation (pag. 6-31 6-31 or Fig 6-9):as you can see the the connections areAnalog PCB Cable from Analog PCB Triax Output Connector (fig 2-2 manual)-------------- ------------------------ -------------------------------Exterior Black Insulator Chassis Common (Outer Triax Shield)Output Common -------> Silver Braided shield * --------> Output Common (Inner Triax Shield)Insulation 1 (Clear)Analog Common -------> Copper Braided ShieldInsulation 2 (Clear)Output -------> Silver Center Conductor -------> Output HI (Center Triax Condutor)The analog common is just the guard voltage there, so that the Copper Braided Shield is there just to protect the output conductor from any leakage.When the unit is turned on the guard white JIO14 (4mm banana jack on the back) and that conductor are connected together with the relais K307.My questions/observations are now:1) Why stop the guard at the triax JIO13 and not connect that with the Inner Triax Shield? The output common could have been connected to the Outer Triax Shield. Probably safety reasons?2) The damage I did exposes just the guard, so any leakage there is not critical. The PTFE is reasonable there for the max 100V you could have between guard and ground common.3) Why Keithley left so much space between the end of the Silver Center Conductor and the end of the Copper Braided Shield? It is not better to protect with the guard as much as you can?To repair my damage this is my current plan:1) cut 7-8mm of the Silver Center Conductor2) Use the PTFE pipe I found there (see fig 2 and 3 from my old post) to cover the damageif my assumptions are correct I will also reduce the leakage current at the connector triax since there is less Silver Center Conductor exposed without guard (probably about .00001% improvement).

author: Zucca
author_rank: Unknown
timestamp: March 08, 2014, 09:14:02 am
content: Just a heads up, the Trompeter Emerson BJ157 previously posted by me will not fit since it is a small Triax 3 lug.I will come back with pictures and details.We will never give up...

author: rastro
author_rank: Frequent Contributor
timestamp: March 08, 2014, 02:38:41 pm
content: Hello zucca,Thank you for the alert. I was going to order a BJ157 connector soon - glad I procrastinated.I still think the Pomona 5219 is a potential candidate. It may have enough clearance without having to mill or cut any of the panels.There seems to be a couple of different datasheets; one has a drawing and the other a photo (assuming it's of the 5219 connector).Datasheet with photo:http://www.pomonaelectronics.com/pdf/d5219_100.pdfUsing the picture and creating a scale using the quoted "connector length dimension" to that of the picture. It would appear that there is enough threaded length to accommodate the 220 panel without modification.Also the Pomona 5219 is priced ~$23.00 on mouserhttp://www.mouser.com/Search/ProductDetail.aspx?R=5219virtualkey56520000virtualkey565-5219Regardsrastro

author: Zucca
author_rank: Unknown
timestamp: March 08, 2014, 03:42:27 pm
content: Indeed rastro, you read my mind. I am returning the BJ157 and ordering the Pomona 5219. Keep you posted!

author: Zucca
author_rank: Unknown
timestamp: March 12, 2014, 04:42:19 am
content: Movie Title:"Triax, a standard for who? "Main Actor:"Forgetaboutit Frank"Director:"Law Murphy"in cooperation with:"Incomplete Datasheet Inc."Left side: BJ157Right Side: 2 Lug Triax (Old Keithley 220)The Pomona 5219 are ordered, let´s see how this movie will end.

author: rastro
author_rank: Frequent Contributor
timestamp: March 12, 2014, 01:36:49 pm
content: Hello zucca,You have a good sense of humor. This triax replacement is really confusing. There seem to be a number of standards(?) with little clear explanation.Regardsrastro

author: Zucca
author_rank: Unknown
timestamp: March 15, 2014, 03:55:47 am
content: Finally some good luck,and it fits perfectly with the metal & teflon pipe used in the old connector, super!BTW 0.050" Max Panel (seehere) thickness my ace:we can use it up to 0.125", just 250% error who cares...double palmin my face... U N B E L I V E A B L E !Now it is time to file the mounting hole....and get the job done...

author: Zucca
author_rank: Unknown
timestamp: March 17, 2014, 03:35:52 pm
content: Here the stencil, happy filing! Make sure to prinit it 1:1 to paper without any "fit to page" or similar settings active.EDIT: PLEASE BE AWARE THIS IS THE SUGGESTED MOUNTING HOLE PATTERN FROM THE POMONA 5219 DATASHEET, ACCORDING TO MY EMPIRICAL MEASUREMENTS THIS IS WAY TOO BIG! DO NOT TRUST THE DATASHEET!

author: rastro
author_rank: Frequent Contributor
timestamp: March 17, 2014, 09:42:36 pm
content: Is the diameter on the pomona 5219 larger than the original connector?

author: Zucca
author_rank: Unknown
timestamp: March 18, 2014, 04:50:40 am
content: Hey rastro, thank you to stay with me in this pure madness. Yes the Keithley connector is a D5 hole (see my previous posts) and the Pomona 5219 is a D4.See the comparison between the suggested hole from the Pomona 5219 datasheet and the Keithley stock hole:Moreove it is facebook official do not trust the Pomona 5219 datasheet, that hole is too big. This is the pattern I will use,Please be aware of the declared +-0.005" tolerance on the datasheet, so please measure your Pomona 5219 and then decide what to do.

author: rastro
author_rank: Frequent Contributor
timestamp: March 18, 2014, 05:06:29 pm
content: zucca,Thanks for the comparison picture and posting the template.I am also wondering about the solder process and best approach to avoid damage and contamination during removal of old and install of new connector.For removal:-----------------------------------1) looks like you have to cut back the outer heat shrink - can't slide it back to expose solder joints2) Unsolder outer sleeve from old connector tab. In my case this tab is broken (motivating reason to replace)3) At this point I'm not sure if there is enough wiggle room to slide back the metal sleeve and outer shield in order to expose the center wire/connector solder joint.My preferred approach is to use original connection points and avoid stripping cable for new contacts. I'm not sure if this is realistic.For Install:----------------------------------1) looks like a tight fit for a solder iron tip to reach center connector pin and wire without touching cable insulation.I thought about preheating pin from other side with a different solder iron set low to ~100-degree C. This might speed up solder flow at the rear of connector and reduce solder heat exposure time on the cable.2) What kind of solder(flux and metal/mix) to avoid affecting impedance?3) What is the ideal solder iron temperature for solid connection but minimum risk of damaging nearby insulation.Thanks for all your postings - I'm sure there is more than a few 220 owners who want to do this replacement.Regardsrastro

author: Zucca
author_rank: Unknown
timestamp: March 19, 2014, 04:48:19 am
content: Hi Rastro!For removal answers:-----------------------------------1) Yes, you have to do a surgery and gently cut the heat shrink with a scalpel.2) That´s exactly what I did3) I then desolder the black common wire at the other side of the metal pipe4) At this point I could slide the metal pipe a little bit back and get the iron on the central conductor to disconnect the Triax connector5) Finally desolder the metal pipe and remove the teflon pipe inside.As a general procedure use the iron only for the shortest time, you will avoid to damage the isolation like I did.Quote from: rastro on March 18, 2014, 05:06:29 pmThis was my plan too, but I think it is not realistic. A small amount of well done stripping it is not a problem.Quote from: rastro on March 18, 2014, 05:06:29 pmI'm a happy Metcal iron owner and I can not set the temperature. To me the key is presolder, use little flux a clean all up with an antistatic brush and IPA.I will document my install process soon.Tonight the Pomona 5219 was on my Keithley, I did it!Initial setupafter 15min of filingdone:Here in attachment the stencil I used, it was slightly small but better so than insane big like in the datasheet, with 2 more minutes of filing I reached the perfect spot.

author: Zucca
author_rank: Unknown
timestamp: March 21, 2014, 05:01:30 am
content: It was a long surgery but now the patient is doing very well.First of all I wanted to make sure my salivation and my finger printer are not causing any problem on such a delicate electronic. Moreover I cleaned the Teflon and the metal pipes with IPA prior the installation.Heat shrinks... how many times I forgot that... The big is for cover the 5219 chassis, the small for the entire central stuffcleaning up the metal pipe from the solder blob from the past (wick and then IPA):presolder the central concuctor on the Pomona 5219Now the funny part, cut and strip the Triax cable to get this (use a scalpel and a lot of patience, take your time). Presolder the central conductor.Basically you want the Silver Braided shield as long as possible (do not cut it if it is possible, keep it from what you get from before) because the Pomona 5219 has a different geometry from the original Triax connector, so the metal pipe has to go further deeper.insert the Teflon and the metal pipe. The Silver Braided shield should stay outside, keep the Teflon pipe slightly out from the metal pipe"Eagle is landed, over"With a scalpel use the sharp blade to pull gently the Teflon pipeso the central conductor is totally coveredI used a little flux to solder the metal pipe on both ends, and then clean it up with an antistatic brush and IPA. Next step solder the metal pipe to the Pomona 5219Don´t forget the common wire for the Banana jack on the back, pass it inside the heat shrinks:It´s time to solder that wire and the Silver Braided shield with the metal pipeDo a quick functional check to see if everything still works, if it pass let´s manage the heat shrink, too easy nowDoneDoes it still works? Yes, cheers!If someone of you need the old Keithley 220 connector just PM me.

author: Vgkid
author_rank: Super Contributor
timestamp: March 21, 2014, 05:13:06 am
content: Good job on the repair, and good beer choice as well. Even though I drink much more wine then beer.

author: robrenz
author_rank: Super Contributor
timestamp: March 21, 2014, 11:35:01 am
content: Very nicely done

author: Zucca
author_rank: Unknown
timestamp: March 22, 2014, 10:11:42 pm
content: Thanks, robrenz and Vgkid,BTW the old Triax is now on sale:http://www.ebay.com/itm/291108474844?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1558.l2649

author: Zucca
author_rank: Unknown
timestamp: June 13, 2018, 12:08:52 pm
content: FYI This unit is now on sale:https://www.eevblog.com/forum/buysellwanted/zucca-sales-(d)-keithley-220/

author: bozidarms
author_rank: Regular Contributor
timestamp: July 20, 2018, 12:18:01 pm
content: Sorry,have not right understand that you sell cables only with Keithley,Thanks