DIY Low EMF cable and connectors - Page 1
Forum section: electronics / general

author: quarks
author_rank: Frequent Contributor
timestamp: February 08, 2013, 02:05:18 pm
content: Hello all,for quite some time, I am experimenting with Low EMF connections/cables. I have different things allready tested and found this crimp spade lugs from AMP (see picture) to be very good. Unfortunately I cannot find it on-line. Does anyone know the partnumber of it or a place where I can find it?thxquarks

author: grenert
author_rank: Frequent Contributor
timestamp: February 09, 2013, 06:56:19 pm
content: Sorry, can't help you with that particular part, but I see that Mouser carries Pomona low EMF lugs with banana plug inserts:http://www.mouser.com/Search/ProductDetail.aspx?qs=LxJU1xRJL0GNFHRHCmLa5A%3D%3D

author: quarks
author_rank: Frequent Contributor
timestamp: February 09, 2013, 07:34:52 pm
content: Quote from: grenert on February 09, 2013, 06:56:19 pmThx a lot grenert,I know the Pomona low emf parts and it is good to know where to get them outside of the USA.For my actual DIY low emf experiments I look especially for crimp spade lugs pure copper (pref. Gold plated and/or with tellur) with low thermal mass (for fast equilibrium; I hope that is the right word).All the parts I found and tried are either heavy Audio versions or tinned copper versions.The above showed AMP is so far the best match to what I want.

author: quarks
author_rank: Frequent Contributor
timestamp: February 13, 2013, 09:38:51 pm
content: Is there anyone else, interested in this topic?If yes, I will keep on asking and posting.So far I found this article very good "Metrology 101 - Watch out for those Thermoelectric Voltages!" (see link)http://us.flukecal.com/literature/electrical-calibration/watch-out-those-thermoelectric-voltages-cal-lab-journal-reprintIf anyone has more useful ideas, how to do more tests, please share.With grenerts good hint, I ordered at mouser some Pomona Low EMF stuff.I made already quite a few comparisons and will keep on testing.PS: Still hope to get a hint for the AMP spade lug or something similar!

author: robrenz
author_rank: Super Contributor
timestamp: February 14, 2013, 01:33:54 am
content: http://www.testpath.com/Categories/Low-Thermal-EMF-Patch-Cords-1410.htm?ctl00_MainContent_Results_ProductListChangePage=1

author: quarks
author_rank: Frequent Contributor
timestamp: February 14, 2013, 05:28:48 pm
content: Hello robrenz,thx for your reply. I probably should have said, that I already have all the Pomona Low EMF parts I could find. I bought them, because it is always good to have a reference.But what I would like to do, is to find out / learn how to measure the effects and what is the best method to do it and finally how my DIY cables will compare. Suggestions are welcome.Here are some parts I work/test with right now (see picture). As soon as I find the spade lugs, I look for, I will make some sample cables with crimped connectors and different cable types (twisted pair, audio, coax and what ever I find worth testing).byequarks

author: grenert
author_rank: Frequent Contributor
timestamp: February 14, 2013, 05:30:40 pm
content: National Instruments has a rather expensive kit with some similar lugs along with other useful parts:http://sine.ni.com/nips/cds/view/p/lang/en/nid/202766They also have a nice white paper on thermal EMF focusing on switching:http://www.ni.com/white-paper/4199/en

author: quarks
author_rank: Frequent Contributor
timestamp: February 14, 2013, 05:38:45 pm
content: Hello grenert,thx again. I will read through the article. The shown parts look quite similar to what I have (probably some or most is from Pomona).byequarks

author: andyb
author_rank: Regular Contributor
timestamp: February 15, 2013, 02:52:08 pm
content: Quarks, I wanted to let you (and others) know that I too have been bitten by the low thermal EMF bug and have been searching around for similar parts. I however, have been looking forSuitable cabling - PTFE insulated, 4 conductor oxygen free with shielding braidLow EMF relays - automated Kelvin-Varley divider, voltage reference scannerSolderI have some preliminary candidates for each, but am still looking. As a note, Indium still manufactures Cadmium bearing solders (though not as pastes - health concerns).

author: grenert
author_rank: Frequent Contributor
timestamp: February 15, 2013, 03:19:09 pm
content: All of the teflon wire I've seen is made of silver-plated strands. Shouldn't that create a thermocouple? Have you found pure copper Teflon cables?Mouser carries low EMF relays.Personally, I would rather have excess thermal EMF than mess with cadmium

author: quarks
author_rank: Frequent Contributor
timestamp: February 15, 2013, 03:53:53 pm
content: Quote from: grenert on February 15, 2013, 03:19:09 pmCopper-Silver should be ok and is suppose to have the same 0.3µV/°C as Copper-Gold. But Silver will have oxidation and I do not know how this will influence.I have ordered PFTE RG196 coax and will check it out.Cadmium also scares me and is probably not allowed to sell/buy in Germany. Therefore I will definitely crimp my Low EMF cables.Quote from: andyb on February 15, 2013, 02:52:08 pmI have not seen PFTE with 4 conductors. If you find some, please let us know. But maybe you should also look for 2-conductor ones.So far I found/read that Belden 8422 (2 conductor shielded) is very good, but I have not yet found a source selling only a few meters.Or if it has to be 4-conductors, try out Conrad Hoffmans secret tip with Telephone Twisted Pair cable.

author: andyb
author_rank: Regular Contributor
timestamp: February 21, 2013, 03:49:22 pm
content: I'm gonna send an email to these guyshttp://jswilley.com/Accessories.htmlWho sell low EMF wire, binding posts, spade and ring lugs. They're in Florida USA, I'll inquire about international orders.

author: andyb
author_rank: Regular Contributor
timestamp: February 21, 2013, 05:21:37 pm
content: Low EMF binding postsPomona 3770 (available at Mouser)IET BP-1000jswilley

author: quarks
author_rank: Frequent Contributor
timestamp: February 21, 2013, 06:11:11 pm
content: Hello andyb,this jswilley looks interesting. Please let us know what you found out.The Pomona 3770 I have bought from Mouser (with all the Low EMF parts they had in stock). They shipped extremely fast (only two days from US to Germany).byequarks

author: PA4TIM
author_rank: Super Contributor
timestamp: February 21, 2013, 06:45:41 pm
content: Quarcs, on your picture I see a shielded double banana lead. Do you have a partnumber ? They would be ideal for connections between calibrators and KVs and I need them for my GR-1620

author: quarks
author_rank: Frequent Contributor
timestamp: February 21, 2013, 07:32:18 pm
content: Quote from: PA4TIM on February 21, 2013, 06:45:41 pmHello PA4TIM,these are from ESI and I have two versions. On the cables is a label # ESI 9347 (length only 28cm) and # ESI 9281 (length 56cm).I like them very much and would like to have more (with other length), but I think they are not available anymore. If you find a source please let me know.byequarks

author: quarks
author_rank: Frequent Contributor
timestamp: June 13, 2013, 12:59:08 pm
content: short updateabout jswilley, 2758-Fork seems to be quite good (Price is 2.40$/each), they also have 4-conductor Teflon cableIf there is anyone out there who knows where to get/find the AMP gold spade lugs, please let me know.byequarks

author: quarks
author_rank: Frequent Contributor
timestamp: April 11, 2014, 08:01:58 am
content: because I am still searching, here is a short update.Does anyone know where to find these JST spade lugs?thxquarks

author: quarks
author_rank: Frequent Contributor
timestamp: May 04, 2014, 03:49:43 pm
content: does anyone know what the name of these or similar cable "split" parts is and where to find/buy them?

author: robrenz
author_rank: Super Contributor
timestamp: May 04, 2014, 06:28:45 pm
content: I thought those type were injection molded onto the wires.

author: quarks
author_rank: Frequent Contributor
timestamp: May 04, 2014, 06:41:06 pm
content: Hello robrenz,when I look at them, they look like cliped together and not molded. But these cables are extreme expensive, therefore I do not want to try to open/damage them. My guess is, they are from Pomona, but they do not seem to offer them for DIY assembly.Byequarks

author: robrenz
author_rank: Super Contributor
timestamp: May 04, 2014, 07:12:08 pm
content: I could not find any that clip on. My google fu is not good enough.

author: quarks
author_rank: Frequent Contributor
timestamp: May 05, 2014, 08:44:35 am
content: here is a closeupDoes anyone know what the name for these parts is?

author: robrenz
author_rank: Super Contributor
timestamp: May 05, 2014, 11:19:26 am
content: I agree that looks like two pieces,notmolded on. It may be solvent or ultrasonic bonded. Is there any relative motion between the halves at all when firmly rotated in opposite directions? Even if there is it does not mean they will snap apart without damaging the snap features. The only reason I mention this is there may be manufacturers Identification on the inside of the pieces.

author: quarks
author_rank: Frequent Contributor
timestamp: May 05, 2014, 01:11:05 pm
content: Hello robrenz,it is showing very little movement, but I do not want to take the risk to break it.Also I do not need the same part, only looking for something similar.byequarks

author: Shock
author_rank: Super Contributor
timestamp: May 05, 2014, 04:35:30 pm
content: They could be called breakout, splitter, Y cable, cable pants or cable splice kits if there is such a part.The ones I have seen are way larger for mains power or telecoms and this doesn't look like a crimp part at all.It's got to have strain relief so I think they are spliced soldered glued and insulated.They would be better soldered anyway especially using a never fail splice technique.I wonder if there is a book on how to make more complex splices.

author: quarks
author_rank: Frequent Contributor
timestamp: May 05, 2014, 07:20:47 pm
content: Hello Shock,thanks for your reply.Splicing is nothing I would think of, for my very high accuracy metrology application.What I know so far, crimping should be the best for this kind of low EMF cables.Solder with Cadmium could be another option, but I do not have it and would probably not even use if I could get it.The "thing" I am looking for is something like in my above pictures or maybe like the attached pic.What I hope to find can also just be a kind of "heatshrink breakout" for 3 conductors.thanksquarks

author: robrenz
author_rank: Super Contributor
timestamp: May 05, 2014, 07:30:38 pm
content: lookhere

author: HighVoltage
author_rank: Super Contributor
timestamp: May 05, 2014, 08:39:07 pm
content: quarks,If this AMP lug is still made, you can get it from Tycowww.te.comIf you can not find it on their parts finder site, just send them an email with the picture attached.I needed a few connectors that I could not find and within hours I got an answer.Even better, they send out samples for free.Hope this helps.

author: Shock
author_rank: Super Contributor
timestamp: May 05, 2014, 08:51:12 pm
content: Quote from: quarks on May 05, 2014, 07:20:47 pmThere is also "cable pants" which I mentioned above but these break out normally into 2 or 4.Then there is this wire splice

author: quarks
author_rank: Frequent Contributor
timestamp: May 06, 2014, 03:39:36 am
content: Quote from: HighVoltage on May 05, 2014, 08:39:07 pmThanks for your reply. I have done this and also had several conversations with TE in Germany. But unfortunately they did not know this spade lug and did not find a similar product they can offer. I do not know if they also contacted/asked US colleagues about my request, but maybe it is worth another try to contact them again.Byequarks

author: quarks
author_rank: Frequent Contributor
timestamp: May 06, 2014, 03:49:37 am
content: Quote from: Shock on May 05, 2014, 08:51:12 pmThanks againI will have a closer lookByequarks

author: wiss
author_rank: Frequent Contributor
timestamp: May 06, 2014, 07:06:00 am
content: Quote from: quarks on May 05, 2014, 07:20:47 pmDo one really need low thermal EMF solder here? When you solder two wires together (using splicing) there will be a large area connecting the two similar metals over a thinner dissimilar solder layer, the temperature going from copper to solder to copper should be very constant. Or do I miss something?

author: babysitter
author_rank: Frequent Contributor
timestamp: May 06, 2014, 07:09:59 am
content: Hi quarks,if you want to attach several multi-stranded wires like this, I would simply use a oversized crimp terminal, shown in the image connecting just 2 wires for lazyness. No intermediate metal, no seebecking, no worries (please prove my reasoning)To get the cables that should go out in one direction into a nice parallel shape, feed them through a block of plastic with parallel channels drilled or a comb-like structure.Add heat shrink tube and fill with hot melt adhesive if desired (you can buy heat shrinking tube with glue inside).Edit about solder:Thermocouple people talk about a "Intermediate metal law" that basically says: Don't care at all if joints are on the same temperature - what I consider given at any moderate-sized soldering joint at the wire to pcb level.

author: quarks
author_rank: Frequent Contributor
timestamp: May 12, 2014, 09:00:44 am
content: short updateIt is very strange, that the manufacturers do not seem to know about their own products.I contacted AMP/TE and JST and send them my pictures of their original products and had several mail discussions, because I received feedback these products do not exist, which seems absurd, because I have them in my hands and they are from original FLUKE cables.That is really frustratingAny ideas?

author: quarks
author_rank: Frequent Contributor
timestamp: July 02, 2014, 04:18:37 pm
content: short updateI only have a few more parts to order, before I can finalize my experiments.Although I spend way to much time and money for this, I am quite happy with the results.My cables seem to be at least as good as my "reference" cables from FLUKE.When looking at the original Fluke Low Thermal Test Lead Set (see att. picture 7003), I wonder why they choose to use a Nickel-plated banana plug, instead of a Gold plated banana or just another spade lug for the guard.Because they ask for >1000$ for the set, cost for the plugs should be no reason at all.Does anyone know or have a guess why Fluke did that?For my own DIY cables I have not yet decided what to prefer for the guard connection.Maybe I will go for a plug-in type separable guard connector. This way I could easily go from no guard at all to 4mm banana or to a spade lug, whatever seems more useful for the task. Right now I alternate between 2mm or 4mm plug or maybe an Anderson Powerpole connection.If anyone has other/better ideas/suggestions, please let me know.byequarks

author: robrenz
author_rank: Super Contributor
timestamp: July 02, 2014, 04:40:01 pm
content: Quote from: quarks on July 02, 2014, 04:18:37 pmIMO thermal emfs are of no consequence on the guard terminal so that would make sense to me.

author: quarks
author_rank: Frequent Contributor
timestamp: July 02, 2014, 05:22:11 pm
content: Quote from: robrenz on July 02, 2014, 04:40:01 pmHello robrenz,yes that is right, for the guard there is no need for a low emf connection and therefore a Nickel plated banana will be no problem.But why not did they mix spade lugs with 4mm banana or why not a least a Gold plated banana.For the extraordinary high price and the expected very low volume they sell, I just do not understand why they should even try to save a few cents on these parts.byequarks

author: robrenz
author_rank: Super Contributor
timestamp: July 02, 2014, 05:31:49 pm
content: I agree, why skimp with a nickel plated banana jack on a already overpriced item?

author: quarks
author_rank: Frequent Contributor
timestamp: November 06, 2014, 06:42:13 pm
content: Here is a short update for those who are still interested.I achieved excellent results with the Fluke 5440A-7003 design (see att. picture of my final product).

author: robrenz
author_rank: Super Contributor
timestamp: November 06, 2014, 06:57:12 pm
content: Quote from: quarks on November 06, 2014, 06:42:13 pmNicely done! Are you able to determine if these are better performing than what you used before?

author: quarks
author_rank: Frequent Contributor
timestamp: November 06, 2014, 07:43:59 pm
content: Hello robrenz,with DC Volts and my "normal" but high quality MultiContact and Hirschmann banana plug leads, I see difference at best of about 1 µV compared to my >1000$ Fluke cables. With my DIY cable I get same (or very close within around 0.1µV) results, compared to the reference cable.Besides the low emf aspect, for high resistance measurement also the better insulation material helps a lot to get more accurate results.byequarks

author: amiq
author_rank: Regular Contributor
timestamp: November 06, 2014, 07:55:56 pm
content: Quote from: quarks on November 06, 2014, 07:43:59 pmSo which parts did you use in the final design?

author: wiss
author_rank: Frequent Contributor
timestamp: November 06, 2014, 08:29:59 pm
content: I've been thinking about this a bit...What about DIYing the gold plating?I googled and there are apparently a lot of "cheap" DIY gold plating kits around...Do you or do you not want the nickel layer for low T-EMF applications?Do you want a thin or thick gold layer?Do you want pure gold or copper-gold?

author: quarks
author_rank: Frequent Contributor
timestamp: November 07, 2014, 07:55:22 am
content: Quote from: amiq on November 06, 2014, 07:55:56 pmHere are the parts you need for the "Fluke 5440A-7003" design:Belden 8719 or similarhigh quality crimp spade lugs (pure copper, direct Gold plated, like the above metionend types or METAS Swiss special lugs see att.)4mm banana plug (Fluke used Pomona and I used MultiContact)high quality wire stripper (for Teflon insulation)high quality crimper with exact fitting die for the lugs and wire size you use

author: quarks
author_rank: Frequent Contributor
timestamp: November 07, 2014, 08:35:02 am
content: Quote from: wiss on November 06, 2014, 08:29:59 pmUnfortunately I have no experience with DIY Gold plating, so I hope someone else can share some information.Sor far my guess is, the DIY plating is only for a nice shiny look and will wear off as soon as you tighten the screws on.The gold should be electro plated with no layer between copper and gold. Gold thickness of 6 µm seems to be adequate.In my research I had problems to find pure copper spade lugs (I even build my own small batch).TE/AMP and JST answered to my request, they do only have tinnend lugs.Direct Gold plating is normally not offered when you ask for plating in the industry. They always suggest to use a diffusion barrier, but direct plating can be done on special order.My best offer was around 50€ min. order value (plus tax and shipping cost), when I send them blank (untinned) lugs.

author: wiss
author_rank: Frequent Contributor
timestamp: November 07, 2014, 09:47:52 am
content: Quote from: quarks on November 07, 2014, 08:35:02 amMe neither, but SWMBO works with sputtering, and spontaneous were something like: "Thick layers will peal off due to the strain"But then she mostly do compounds on metal/silicon.Thickness will be linear to the time you plate it (?) Just run for a longer time...Quote6 um isn't that thickCan "easily" be done in sputtering, which is very slow compared to electroplating.QuoteWithout the nickel-barrier copper will diffuse through the gold and end up on the surface and oxidise, not good at all with copper-oxide there...The nickel-layer will be thin and in very good thermal contact with both the copper and gold, no net EMF.

author: robrenz
author_rank: Super Contributor
timestamp: November 07, 2014, 12:23:15 pm
content: IMO forget the gold and use bare copper and DeoxIT. That is Agilents approach on their nano voltmeter.

author: quarks
author_rank: Frequent Contributor
timestamp: November 07, 2014, 01:07:28 pm
content: Quote from: robrenz on November 07, 2014, 12:23:15 pmWhen I send my request to the crimp lug manufacturers, I also asked for bare copper spade lugs, with the same result, they only offer tinned lugs.So far (besides ebay) I have not found DeoxIT in Germany.And with equivalent products from "Kontakt Chemie" I am not happy with my handmade lugs (see the one in the middle).

author: robrenz
author_rank: Super Contributor
timestamp: November 07, 2014, 02:45:28 pm
content: If you want some machined from solid copper send me a drawing of the critical features and I will solid model what I would machine. They could have exact fit of wire and insulation diameters and slot width etc.. Tell me how many you would want and I will quote a price.

author: quarks
author_rank: Frequent Contributor
timestamp: November 07, 2014, 03:32:23 pm
content: Hello robrenz,thanks a lot for your offer.But I am not searching anymore and also would feel bad if, I would even ask you to spend time for this.I guess we are a little bit carried away with the DIY gold plating question from wiss.Because I only answered his questions with what I found out during my research and tests.Right now I already have more parts than I will probably ever need in my lifetime.Maybe I should even think about selling or trading some of the parts I bought and build for this research.Byequarks

author: robrenz
author_rank: Super Contributor
timestamp: November 07, 2014, 03:43:12 pm
content: No problem, just trying to help out on the never ending quest

author: bingo600
author_rank: Super Contributor
timestamp: November 07, 2014, 10:42:31 pm
content: Quote from: quarks on November 07, 2014, 01:07:28 pmquarks i got my deoxit from Holland , shipping shouldn't be bad to .dehttp://www.schreeven.nl/3313-deoxithttp://www.schreeven.nl/3315-deoxit/Bingo

author: eas
author_rank: Frequent Contributor
timestamp: December 03, 2015, 06:25:46 am
content: Why do you suspect the existing 4mm banana sockets on your DMM (K2015?)?Also, think about the thermal characteristics of the long, thin pin used to connect the lead from the PCB to the back of the stock banana jacks.

author: macboy
author_rank: Super Contributor
timestamp: December 03, 2015, 02:58:54 pm
content: There is no reason to suspect that the Keithley input jacks and the leads from them to the board are anything but great. Keithley are among the masters of low level measurements. The input jacks are likely made of tellurium-copper. This has two very important properties: it has nearly identical thermo-electric properties to pure copper which result in low thermal EMF connections (to copper and like materials), and it is much harder than pure copper, making it more durable and easier to machine/manufacture. They are likely gold plated, which adds virtually no thermal EMF effect, since the gold layer will be at a constant temperature throughout. Then any thermal EMF generated from plug to gold plate is cancelled by the opposite thermal EMF from gold plate to CuTe jack bulk metal. The gold plating is there to minimize oxidation, which would cause much worse thermal EMFs than the gold does, so it is a compromise of sorts. The same goes for the pin connection at the back of the jack. That lead is probably terminated in a gold plated CuTe connector. Don't forget too that these are inside the controlled environment of the meter, and after it has been properly warmed up and stabilized, no additional thermal EMFs will creep in (those that so exist are constant and will be nulled out during calibration). Remember that the value of low thermal EMF connections is to minimize EMFs due to temperature gradients that are beyond your control. Sticking your finger onto an internal connection of a meter running without its cover doesn't count

author: Huluvu
author_rank: Regular Contributor
timestamp: December 03, 2015, 05:32:46 pm
content: I don't get the Idea or reason behind why Tellurium should be good for Low EMF parts.Tellurium itself has a much worse thermal EMF than Gold or CopperThe only technical reason I found was the faster machine / manufacturing cause.Any other explanation for the Tellurium Hype?

author: timb
author_rank: Super Contributor
timestamp: December 03, 2015, 06:13:24 pm
content: Quote from: Huluvu on December 03, 2015, 05:32:46 pmFrom what I've seen, it's not. Pure copper is best, but it oxidizes quickly.Pure Copper + DeoxIT would be the best solution. It just takes a lot of maintenance.Sent from my Smartphone

author: eas
author_rank: Frequent Contributor
timestamp: December 03, 2015, 10:44:01 pm
content: Quote from: 3roomlab on December 03, 2015, 08:55:09 amHow important is it to minimize thermal EMF when the case is open and you are touching things? I'd think it isn't very important at all. With the case on and the device given its proper warmup period, I'd guess that both sides of the PCB joints are effectively the same temperature, as are both sides of the switch contact points, and both sides of the internal connection to the tip of the panel jacks. Moreover, they are all paired, and the pairs are probably at similar temperatures. All of which adds up to minimal thermal EMF in actual operation, and what does exist, is mostly cancelled out.Sudden changes to the outside temperature will upset the equilibrium. Plugging leads into the jacks will also upset the equilibrium, and take a little time to equalize. If you really want to avoid the time to equilibrate when inserting room temperature leads into the case-temp jacks, it might make sense to have some extension leads that you leave plugged in.As for wear and tear on the panel jacks exposing the underlying copper to oxidation. It could happen. Replacing the jacks shouldn't cost much, take much time, or involve much risk. I think there is a good chance that it wouldn't make a lick of difference, but just replacing them would address your concern without the time required to test the situation. If you do replace them, I strongly suggest that you replace them with the original pin style, rather than the blade-lug style you linked to, because my guess is that the pin stretches the thermal gradient between outside temp and internal temp over a longer distance thus reducing differences between internal lead and socket temps.Stepping back, I have a larger suggestion for your effort to improve upon the performance of you DMM. Before you break anything else inside the DMM, consider making an external measurement pre-amp that will take low-level signals and produce a suitably low-noise +-10v output that you can feed into the DMM. Once you've got that working well enough that it matches the noise and sensitivity characteristics of the 1v and 100mV ranges on your DMM, you'll have a much better idea of what it will take to hack your DMM to actually improve its performance. You might even start with the reverse-engineered Keithley 2000 schematics and duplicate the relevant parts of its front end circuitry.

author: robrenz
author_rank: Super Contributor
timestamp: December 04, 2015, 02:50:17 pm
content: Quote from: Huluvu on December 03, 2015, 05:32:46 pmIMO Tellurium copper is purely for machineablity. Pure copper machines like crap and the parts would cost much more because of it. Tellurium copper is not an electrically tuned alloy, it is a free machining Copper that gets used because of its machinability period. The rest is hype generated by tradition/lack of understanding.

author: Gyro
author_rank: Super Contributor
timestamp: January 04, 2016, 12:48:37 pm
content: Teflon wire / cable is usually (not able to say always) silver plated.

author: alanambrose
author_rank: Frequent Contributor
timestamp: February 28, 2016, 11:24:11 am
content: Hi Quarks,Do you have any measurements you can share with us?A misc update:(1) I also found some silver plated over copper / PTFE / twisted pair + screen cable which I plan to test. It was on UK eBay at £10 for 3m. I think people are buying this for audio.(2) BTW here are jswilley prices I got in Jan '16:SPSCTCS-4 is $7.75 per footSTC-4 is $5.50 per footlow thermal binding posts $25low thermal forks and rings are $2.99(3) I just ordered some small ENIG pcbs to fit the 3458a terminals to use as shorts / to hold standard vishay resistors. I'll let you know how these gohttp://anagram.net/nuts/Low%20Emf/Images/low%20emf%203458a%20shorting%20bar.JPG(4) For the truly OCD, I designed this little thing to shape copper wire for 3458a short:http://www.shapeways.com/product/GAG65ZGSB/3458a-copper-short-forming-toolI have not actually tested it out yet. Don't panic, I make exactly 0.00 on eachThe little lip is there to make it easy to hold in a vice if you want.Alan

author: VK5RC
author_rank: Unknown
timestamp: February 28, 2016, 12:33:54 pm
content: I am not in the league of you guys, I made a simple set of lower Thermal EMF banana leads using this cable.http://www.ebay.com.au/itm/381447862950?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AITI used these banana plugs;http://www.ebay.com.au/itm/10-Premium-4mm-Gold-BANANA-PLUGS-Twin-Screw-Cable-Connectors-Soft-Feel-Covers-/300776381856?hash=item4607ab5da0:g:CZMAAMXQDfdRpUNyThe covers when tested with an insulation tester come out OK,The springs on the tip are nice and firm and appear well bonded to the body (they do not rotate) , I GUESSED that a screw clamp (or two) would be closer to crimping than soldering, but I must admit that the really high thermal EMF of copper oxide has me still leaning a little toward soldering to some degree. It must be really hard to oxidise under a solder joint! I am a bit of a solder fan boy - I must come into the 20th Century.

author: timb
author_rank: Super Contributor
timestamp: February 28, 2016, 01:12:58 pm
content: The high pressure of a crimped connection creates a cold weld and the metals are bonded together, so there shouldn't be any oxidation if the copper is cleaned before being crimped.The problem with solder is that you're adding a dissimilar metal (lead) into the mix, which can create additional thermal EMF.

author: quarks
author_rank: Frequent Contributor
timestamp: February 28, 2016, 03:05:14 pm
content: when I made my comparisons I compared all my different cables and connectors with the same settings on the DMM (Fluke 8508A) and on the same 10 VDC reference (Wavetek 4808). The results between my DIY and the Fluke low EMF "reference" cables were practically identical. The averraged results were mostly only in the 0.1 µVolts, which is not really meassured, because that is the last digit, which is not always perfectly identical, even when you use the same cable again.With my other good cables I saw differences around 1 µV. But that is still ok for 10VDC because that is only 0.1ppm.My conclusion and ranking was:1. use good quality cables with high quality insulation material like PTFE (avoid PVC)2. use crimped gold plated copper spade lugs for all precision measurement (avoid nickel plating)3. use low emf 4mm banana if you do not have the above (i.e. Pomona, MC)4. use good 4mm banana (in my case Hirschmann and MC, both with welded on cable), if you do not have the aboveAnd use the very same cable, when you do high precision comparison meassurements or calibration, whenever possible and wait long enough for temperature equilibrium.att. you can see some cable madness (the pile shows most of my low emf reference cables from Fluke, Pomona and ESI)

author: quarks
author_rank: Frequent Contributor
timestamp: February 29, 2016, 11:15:09 am
content: Quote from: alanambrose on February 28, 2016, 11:24:11 amHello Alan,about the shorts, that is very interesting please share where to buy.Also the "3458A Copper Short Forming Tool" looks very good.Att. is a collection of shorts I mainly use.As you can see my own 3458A short does not look good at all. So it would be very handy to have this jig.byequarks

author: quarks
author_rank: Frequent Contributor
timestamp: February 29, 2016, 12:45:20 pm
content: here are some links (Transmille videos) to the low emf cable subject:Making Good Measurements - Effect of Test Lead Resistance on Measurement ErrorMaking Good Measurements - How to avoid thermal EMF errors

author: alanambrose
author_rank: Frequent Contributor
timestamp: March 05, 2016, 09:51:55 am
content: >>> I also found some silver plated over copper / PTFE / twisted pair + screen cable which I plan to test. It was on UK eBay at £10 for 3m. I think people are buying this for audio.BTW I did test this (10V from 732a into 3458a at NPLC=2, AZERO=ON) and it is not much of improvement over cheap twisted-together banana leads.For both setups, I'm getting 0.06-0.07 ppm rms noise - which I think is pretty good for the bananas actually. This is with soldered ends on the PTFE leads, no lugs. Neither using the shield as guard or running the 732 off battery seems to make any difference. I think I need to do some more careful measurements...and get some lugs to crimp on some new cable...A.

author: acbern
author_rank: Frequent Contributor
timestamp: March 05, 2016, 05:43:25 pm
content: I have seen some considerable EMF voltage from certain banana plug cables, but not on all. So indeed, depending on the cable, sometimes no relevant difference when using standard cable. But you do not want to guess that, so desoite this, for precision measurements, I dont take the risk, not worth it.

author: martinr33
author_rank: Frequent Contributor
timestamp: September 25, 2016, 02:02:54 am
content: I've been looking for copper banana plugs, because I am getting measurement offsets with my current cables (Nakamichi jacks on copper wire). I'v purchased many types from eBay, including Nakamichi from, several suppliers. I run them on my sander to see if they are really copper.Bottom line is everything I have found that is gold plated is always brass, no matter what claims are on the web site.I did find some on eBay with the description of "pure red copper". Although some are plated copper (and say so) the ones I picked up are copper through and through. They run about $4 each. I use them with silicon insulation 10GA wire, works well.I also picked up some Mueller copper alligator clips. I soldered the end of the wire to the inside of the alligator clip, and then crimped to body of the plug to the wire.So we'll see how these do.

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: September 25, 2016, 02:23:00 am
content: Do a search for Furez TSTWP30NP. I bought some and used them for a Keithley 181 cable. Yes, these do appear to fall into the audiophoolery category but they seem to be real. Real expensive if you include shipping. Also they are not shielded.It is prone to scratching so a clean binding post will save on the wear and tear.

author: Robert763
author_rank: Super Contributor
timestamp: September 25, 2016, 06:12:25 pm
content: Raychem make heatshrink transition boots e.g. Raychem 462a011-25-0 Check ebay.The gold plated amp lugs may be standard tin plated ones that have had the tin plating stripped and then been gold plated. Seehttp://www.finishing.com/319/63.shtmlI've used Van Damme professional audio cables for test leads with good results. Some national labs just use 2.5mm solid copper mains installation cables without lugs. They rely on air spacing for insulation and just scrap them when damaged or too short from repeated stripping.

author: martinr33
author_rank: Frequent Contributor
timestamp: September 26, 2016, 01:14:30 am
content: Well - it is confusing. When you are looking at microvolts, everything make a difference. I am not saying that the laws of physics are suspended, but that we do need to think very carefully about where the various EMFs come fromThermal EMFs come from two dissimilar metals in contact. In the case of plating, assuming that the copper is the same as the copper in the wire (it isn't, but that is OK for now), you end up with a copper to brass junction.Now, the copper test lead wire creates a canceling brass to copper junction, and as long as the jack is at the same temperature all through, there's no voltage because the two junctions cancel out. But if the tip is warmer than the body, there is a net voltage - and that matters at the microvolt level.I am still messing with this. My new leads are definitely better, but I still have offsets. I might have copper oxide in my meter connections. The jacks are really, really red - my wire is more yellow.And I would like to have gold plating, because I know I will be cleaning my copper.Quote from: evb149 on September 25, 2016, 02:49:15 am

author: acbern
author_rank: Frequent Contributor
timestamp: September 26, 2016, 09:49:11 am
content: What meter are you using and what offset do you see?

author: martinr33
author_rank: Frequent Contributor
timestamp: September 27, 2016, 12:26:48 am
content: I won't be back to my meter for a week or two. It is a K2001. I'll measure and post.

author: VintageNut
author_rank: Frequent Contributor
timestamp: September 28, 2016, 02:04:38 pm
content: I have something to add to this discussion. I am in the process of creating a good 100:1 and 10:1 Hamon divider. As part of the parts selection and assembly process, I have to measure single-ppm differential null voltages.Today I watched the a null reading go from 10s of ppm to single ppm over a minute. I thought there was a problem with the source. The problem was cheap banana/alligator cables connected to my divider parts on the bench.I disconnected the voltage sources and divider and just shorted the null meter alligators together. There were were over 10 microvots off offset that slowly drifted to zero after more than one minute. I grabbed one of the shorted alligator clips and held it a few seconds. The offset measurement climbed back up to over 10 microvolts.My point is that is not just a dissimilar metal problem. It also a temperature gradient problem that you have to be looking for.For me, the cure will be to make better alligator cables and to place enough insulation where the alligator is touched to mitigate transfer of body heat to the clip.Touching cables and plugs in the signal chain can create a temporary offset that you have to be aware of. If you do create an offset, you have to wait for the signal chain to come to thermal equilibrium.

author: tggzzz
author_rank: Super Contributor
timestamp: February 12, 2017, 11:47:01 pm
content: Quote from: timb on February 28, 2016, 01:12:58 pmWhat's the effect (or preferably lack of effect) of using lead-free solder or high silver content solder such as 4% Ag, 95.5% Sn, 0.5%Cu ?And apologies for the necropost; I'm only just starting to fall into this bottomless pit.

author: Kenny Powers
author_rank: Contributor
timestamp: February 14, 2017, 07:01:28 am
content: Quote from: tggzzz on February 12, 2017, 11:47:01 pmAlso interested in this if anyone had carried out any tests?I picked up a few feet of Belden 8719, is there any point in me connecting the guard lead on to the shield most of the units I would be testing don't have a guard for eg 34401A. So I could only connect the guard at one end?

author: e61_phil
author_rank: Frequent Contributor
timestamp: February 14, 2017, 07:40:04 am
content: You shouldn't connect the guard twice to LO. If I forgot to set the guard switch on the 3458A into the right position in connection with the 5440B, there will appear some ppm of offsets due to EMI.

author: Kenny Powers
author_rank: Contributor
timestamp: February 14, 2017, 08:41:10 am
content: So you only connect it to one instrument, if they both have a guard terminal? and if not just to the calibrator?Thanks

author: e61_phil
author_rank: Frequent Contributor
timestamp: February 14, 2017, 09:07:09 am
content: If both have a guard terminal it should only connected at one instrument to LO. The 3458A (3456A...) and the Fluke 5440B calibrator have both a switch to disconnect guard from LO. The guard is connected to both instruments.Edit: In case of the 34401A I'm not sure about the best practice. One could connect LO to guard at the 34401 and disconnect the guard from LO at the calibrator. The other way is to connect the guard only to the calibrator. I would prefer the first option.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: February 14, 2017, 01:05:43 pm
content: On Teflon wire, AFAIK it's a high temperature process so tinned wire won't work. Probably problems with bare copper too, so all you find is silver plated wire.I avoid all the crimping and worry by just putting the (clean) wire(s) in the hole and tightening the jack.

author: MisterDiodes
author_rank: Frequent Contributor
timestamp: February 14, 2017, 07:35:05 pm
content: Quote from: Conrad Hoffman on February 14, 2017, 01:05:43 pmThis is by far the best route to repeatable results. In fact, whenever we can in the cal rooms we just leave the wires attached to an instrument - say 3458a - and just trim and restrip the DUT end of the wire for the next test setup. A lot of times the "low Thermal" connectors won't solve whatever is really wrong with your test setup - which is usually caused by poor thermal management.If you're chasing PPM's and repeat-ability, you really want to stay away from "banana" plugs and sockets if you can - good, clean, snug (not squashed) copper to clean copper connections are best. Just a clean copper wire into the cross-drilled hole and snug the nut down. Even better yet is to make sure your connections are at same temp. and draft free. That will get you as good or better results than any "Low Thermal" banana or spade lug setup (for voltage / resistance we don't usually use spades, current measures are where spades can help spread the contact area & lower local heat).Sometimes we will spec an instrument to come modified from the vendor with the recessed banana sockets replaced with binding posts, or they must supply an adapter board that gives us access to make clean copper wire connections as required.Make good use of guard connections also - and those are only connected at one end. Normally you don't want any device-to-device current flow in your guard / shield.If you have to use a connector, a good quality crimp is best, and use the correct crimp dies to achieve a solid connection without weakening the conductor. You don't want to over-crimp the wire so that the conductor starts extruding out from the crimp area - that will cause weird effects also.If the crimp is solid & correct, you normally don't need or want any solder - unless specifically called for. A quick & simple test for a correct crimp setup is to crimp on a sacrificial connector, then clamp down the connector in a vise or similar and pull on the wire until the wire breaks. The break in the wire should -not- occur at the crimp joint. If the broken conductor is at the crimp, then you need to look at your crimp process. Normally a good crimped joint will be stronger than the wire by itself.Obviously, if you do the above test and the wire slips out of the crimp, then that's wrong also.Teflon insulation can help on situations where very small current flows will have an effect. Sometimes PVC insulation is fine, it just depends on what you're measuring and at what voltage.

author: 0.01C
author_rank: Regular Contributor
timestamp: June 18, 2017, 03:36:28 pm
content: Quote from: quarks on April 11, 2014, 08:01:58 amI bought some copper spade lugs from China ,not bad.I use it to made a 34420A test lead.The left side of the picture is original 34420A test lead,

author: 0.01C
author_rank: Regular Contributor
timestamp: June 18, 2017, 05:32:21 pm
content: Quote from: bingo600 on November 07, 2014, 10:42:31 pmThe price of the deoxit HKG agent is the cheapest , can pay via paypal.http://www.clarityd.com/main/en/products/caig/detoxit-d-series-cleaner

author: HighVoltage
author_rank: Super Contributor
timestamp: June 18, 2017, 08:11:38 pm
content: Quote from: 0.01C on June 18, 2017, 03:36:28 pm1.)I don't have a 34420A (but one day I will), so I am not completely familiar with the connector.But your own 34420A cable looks like it has a LEMO connector, is that correct?If so, what is the LEMO connector number?2.)What base PTFE cable are you using for the 34420A cable?3.)What precision resistor are you using to get 10.0000 °C on the 34420AVery impressive !The 34420A is probably one of the best temperature measurement instruments.

author: 0.01C
author_rank: Regular Contributor
timestamp: June 18, 2017, 09:04:05 pm
content: Quote from: HighVoltage on June 18, 2017, 08:11:38 pm1. correct , it is Lemo connector ,original is about $100http://www.ebay.com/itm/95H8756-Agilent-Technologies-34104A-Low-Thermal-Input-Connector-For-34420A-/271810830417?hash=item3f49302051:g:WjQAAOSw2gxYvV6qThere are two Lemo plug can use in 34420A ,https://www.eevblog.com/forum/repair/looking-for-the-input-connectors-for-agilent-34420a/I use China made Lemo ffa 1s (gold plated) $5,2. cable : 3.6mm Teflon silver plated four wire shielded cable $3/M ,copper spade lug 5pcs <$1Total : <$20 (original >$200)3. I used Fluke 518 dry block and L&N 8163 SPRT , 10.0000 °C just can keep 1-2s

author: HighVoltage
author_rank: Super Contributor
timestamp: June 18, 2017, 09:38:21 pm
content: Thanks for this information, 0.01CI have never heard of a L&N 8163 SPRTYou must be doing very accurate temperature measurements.

author: Muxr
author_rank: Super Contributor
timestamp: June 18, 2017, 10:16:14 pm
content: I've been experimenting with these (speaker) banana plugs for my logging measurements:https://www.amazon.com/gp/product/B071LK46PD/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1I've made a few short twisted pair probes with them. And I really like the snug fit and the quality so far.They have two tightening screws as well which makes the cables pretty tough to rip out of them:

author: 0.01C
author_rank: Regular Contributor
timestamp: June 18, 2017, 10:22:12 pm
content: 8163 is a Meyers' type thermometer ,you see my nickname then you will know I like thermometer

author: 0.01C
author_rank: Regular Contributor
timestamp: June 18, 2017, 10:47:05 pm
content: Quote from: Muxr on June 18, 2017, 10:16:14 pmI just find a shop selling nice binding posts,https://world.taobao.com/item/521116800640.htm?spm=a312a.7700714.0.0.2LAU7Z#detailthe 2nd picture is the best type of the banana jack ,because it made by one piece copper

author: z01z
author_rank: Regular Contributor
timestamp: June 20, 2017, 07:20:55 am
content: The big question is, is it copper or brass.If you happen to by them, please check and report back.

author: 0.01C
author_rank: Regular Contributor
timestamp: June 20, 2017, 12:19:55 pm
content: Does anyone have experience with this test leads and are willing to share the results

author: alm
author_rank: Super Contributor
timestamp: June 20, 2017, 01:06:22 pm
content: They also sell the parts (cable, spade lugs) separately on theirown website. This is much cheaper if you need multiple cables.

author: quarks
author_rank: Frequent Contributor
timestamp: June 20, 2017, 01:48:06 pm
content: Quote from: alm on June 20, 2017, 01:06:22 pmthe easiest way is probably to contact eevblog member ap (as he is the seller afaik)

author: 0.01C
author_rank: Regular Contributor
timestamp: June 23, 2017, 09:13:30 am
content: I received eight pure copper binding posts free sample from the taobao seller (Thanks) and already sent to TiN and some members for test the emf.

author: TiN
author_rank: Super Contributor
timestamp: June 23, 2017, 10:23:15 am
content: I just got EM A10 fixed up, also got few Pomona banana's and 3770's to try.If anyone have specific ideas how to run TEMF connector test, I'm all ears. So far idea to hook pair of copper fresh wires to two connectors and measure differential voltage.

author: MisterDiodes
author_rank: Frequent Contributor
timestamp: June 24, 2017, 07:43:53 pm
content: We've found that a 3uV full scale Null meter is your best friend here to look at the differential voltage across the connector, generally easier, faster and more accurate than any DVM for this test. Generally you test close-mounted pairs of connectors because that's how they are most often used in-circuit.It's important to note that you want the connectors mounted to a whatever substrate they will be mounted to because the only thing that is going to generate thermal EMF trouble is if a pair of connectors are at DIFFERENT temperatures. Generally you don't give a whit what the connector thermal EMF is if a pair of connectors in the same circuit are at same temp. In other words mount the connectors on a good thermal conductor and you'll have far less thermal problems, if any.It also makes a difference what wire you're using at the connector and how fast its thermal flow is contributing to a temperature difference at each node.Of course air drafts, ambient temperature, and so on all make things better or worse. The mass of the connection joint area also sets the reaction time of the join.So the concept of "Testing a Connector" really applies to the whole connector, wiring and enclosure SYSTEM and how and where it will be used. Sometimes you find it doesn't matter a whole bunch - and there are much bigger errors in the system.Suggestion: While testing connectors, jacks sockets etc., if they are threaded: use a torque wrench for repeatable torque force on the connection. The clamping force on the conductor and how compression force is distributed makes a difference. Generally resistance measure circuits want a smaller contact area (to reduce changes in R especially in lower ranges), higher amperage flow wants a larger contact area (to lower self-heating) - but use what works best for your application. When testing connectors, you also want to see how -repeatable- the connection is, not just thermal EMF. A clean pure copper to pure copper connection is best, snug and hopefully gas-tight in the metal to metal zone but so the wire isn't extruded or bent. Everything else goes downhill from there.You'll probably find out that one of the best connections ever invented is just two ea. 24AWG solid -clean- copper wires well twisted together...Telco wire / shielded Cat5e wire can work for lots of stuff at DC. If chasing PPM's then teflon insulation will certainly help solve leakage current problems, but silver-plated wire may or may not be an asset.RE: Banana plug - not normally used for low PPM work - they really aren't that repeatable as they age and the plug spring force drops off and inside plating wears away from inside the socket. Binding post is usually preff. for high accuracy / repeatability.

author: TiN
author_rank: Super Contributor
timestamp: June 26, 2017, 01:00:14 pm
content: I've just got 0.01C's kit. Copper connector indeed look very much like Pomona 3770. I've took few photo to illustrate:And here's disassembled (there is no thread stop for top nut part, so it's easy). Plus comparison to Pomona 3770 (from Digikey).And here's idea of testing just connector alone. Just to make it act as a thermocouple, with pure clean fresh wire attached on base and nut part. Perhaps I'll need to add second connector outside of the thermal box, otherwise TEMF will cancel out with just one connector. Purpose is to sort copper-copper connectors vs plated brass ones.Keithley 2002 on 20microvolt range should be well suitable for the task measuring thermocouple voltages.Perhaps 0.01C can be kind for us to have group order of copper 5-way binding posts? I'd be definitely willing to buy 50-100pcs of these and could spread the batches for rest of copper nuts here.

author: MisterDiodes
author_rank: Frequent Contributor
timestamp: June 26, 2017, 05:20:33 pm
content: I would still suggest you test in series connected pairs at some point - because most of the time that's how they will really be used in circuit. i.e. one connector is adding a thermal error, and the second is canceling it out with the same thermal error emf (mostly). Air drafts ruin that theory, of course. Normally if the connector pairs are at same temp the cancellation effect works very well and you don't worry about it most of the time.A decent low thermal post will have a base insulator that has high thermal conductivity - so that when you mount a pair to aluminum or copper base, the connector post pair will be at same temp, or close to it. Those posts in the photo all look like the usual cheaper low-grade hobby stuff, built by people with little or no understanding of how thermal flow works. They way those are built, it will be harder for the connector pair to be at the same temp. even when mounted to a good thermal reference substrate.By the way - always test with the low-thermal connectors mounted up to a proper thermal-conductive base plate. Not plastic!!!If those are real bare copper posts and spades, that's great - that will help!. That also means you clean the connections -every- time. File into the connector and see if they are just plated. That happens a lot, dang!Try different wire sizes on the series-connected pair setup also, and check the difference between spades vs clean bare wire going the the center post hole.Don't forget to test for connection repeat-ability. You'll tend to see that get a bit wonky with banana plugs / sockets after a few hundred cycles. That's why DMM's with binding posts work more repeatably when chasing low ppm's.No Null meter? These are easier/faster than DVM to see what's going on, quickly. You want to put that on your shopping list....once you learn to use one you realize they are quick and easy, and require no real calibration even with an extremely high input impedance near null - which is what you need to check thermal emf effects.Watch out for that amp on there - with the setup you've got it will tend to pick up any noise from anywhere. Make sure to run tests first with just a straight solid connection (without connector in circuit - just twist wires together + wire nut if you have to) and make sure you're at close to zero emf. (i.e. noise floor). Keep your wiring very short, and use your guards too.

author: MisterDiodes
author_rank: Frequent Contributor
timestamp: June 26, 2017, 08:27:29 pm
content: TiN: Another thought...with that amp in there you're be measuring any UN-equal thermal junction EMF's across -all- the front-end connectors in your setup, along with the connectors under test. Just a head's up to watch out for that. You want to keep it all short, tight, shielded / guarded, etc. and thermally equalized everywhere.

author: MisterDiodes
author_rank: Frequent Contributor
timestamp: June 27, 2017, 03:42:29 pm
content: TiN: I showed your test setup to a colleague who works at the IC level doing analog designs, and spends a lot of time looking at thermal junction effects. He cautions that your test setup is going to also measure the cancelling effect of the second connection to the binding post: You've got the threaded end with your sample spade and/or clean copper wire, but if you have a second connection of a soldered copper wire onto the base of the binding post that's going to cancel out the threaded end junction to some extent.He also cautions that you will find out if that amp internally and cable / test jig has thermal-balanced connections throughout.One technique that's used to test a specific connection combination is you make a sample threaded end on a much longer rod of whatever material - and then put a thermocouple on the threaded end and a second thermocouple on the end where you have a soldered wire to complete the test circuit voltage pickup loop. Now you have a way to monitor the temp. of each junction, without any other junctions in between. That way you can have both ends of the rod at different temperatures and thus isolate the effect of -one- junction over the other. You won't be able to do that on a short binding post, the ends are too close together to get a decent temp. spread, probably.If you think you see a thermal EMF, it's a good idea to swap all connections to reverse DUT junction connections and make sure you are really seeing a mirrored voltage level.Again: The main practical strategy in general is to keep all connections at the same temp. and consistent, and then most thermal effects -should- cancel out to a great extent a lot of times - at least below the noise level of whatever other test is going on. If you keep your binding posts / sockets in thermal balanced pairs and sharing the same temperature, it shouldn't matter too much what they are made of - to a certain level of measurement uncertainty.That's the theory. You will find the junction where reality steps in.

author: MK
author_rank: Regular Contributor
timestamp: June 27, 2017, 04:08:15 pm
content: The EM electronics A10 amplifier does have pure copper thermally balanced connectors and has about 1nV rt hz all the way to dc.

author: Ash
author_rank: Regular Contributor
timestamp: June 29, 2017, 11:54:19 pm
content: Hi everyone,I also received my order of copper binding posts from the Taobao seller. It took 2 weeks to deliver here in Australia, which is pretty good for stuff from China (normally takes a month).I'm pretty happy with the quality and as TiN has shown these appear to be a reasonable copy of the Pomona 3770. See the photo.The finish seems to be raw copper, unlike the Pomona ones which are gold flashed. I suspect I may need to invest in some deoxit.Also the Pomona items retain the thumb screw, but that is fine. They fit Pomona banana plugs well, but I'll be using them with solid core wires I expect.One of mine has a slightly bent end where the hole is, looks to be a manufacturing defect. Nothing that will affect the unit in use.So I'm pretty happy with these, especially for the price. Taobao is a bit daunting for the non-Chinese speaker, but I found you can use the "always translate" feature in Chrome and muddle your way through. Essentially it is just like eBay, make the purchase, get the goods and evaluate them. The Alipay service also holds the payment in escrow until you release it. So if you order and are happy, make sure you complete your end of the transactionCheers,Ash.EDIT: the Pomona 3770 is lower left in the photo, the remaining ones are the ones I received from Taobao.

author: 0.01C
author_rank: Regular Contributor
timestamp: June 30, 2017, 01:33:02 am
content: I have some binding posts collection, the most i like are these two.

author: Echo88
author_rank: Frequent Contributor
timestamp: August 02, 2017, 12:34:45 pm
content: Maybe some of you guys find this trick useful:I threw some normal crimp spade lugs in citric acid and after 2 weeks the relevant tin layer was etched away, yielding lowest cost pure copper (according to an exemplary manufacturer >99,9% electrolytic copper) spade lugs suitable for nanovolt-stuff.Of course hydrochloric acid and oxygen peroxide would etch way faster, but i didnt have that stuff lying around.

author: cellularmitosis
author_rank: Unknown
timestamp: August 02, 2017, 02:16:48 pm
content: Very interesting Echo88! I think I'll try that myself.Would something like this work? Powdered food-grade citric acid?https://www.amazon.com/gp/aw/d/B00EYFKKZC/ref=sxts_sxwds-tsp_1_a_it?ie=UTF8&qid=1501683294&sr=1TiN, 0.01C, can you guys post a link to the taobao seller who sells those binding posts? I'd like to order some.

author: Echo88
author_rank: Frequent Contributor
timestamp: August 02, 2017, 04:08:43 pm
content: I used a descaler which contained citric acid, so the mentioned pure citric acid in a solution should work even better i think.

author: pelule
author_rank: Frequent Contributor
timestamp: August 02, 2017, 05:18:10 pm
content: Following low EMF cable (or similar with 4mm plugs) are offered at the bay.A single cable offered some weeks ago first time (@~70 EUR and free shipping) - a "trial" ?Now several cables offered from same seller (49,96 EUR + 21,17 EUR shiiping inside Germany == same price, ridicolous shipping cost).http://www.ebay.de/itm/Low-EMF-Test-Cable-PTFE-4-wire-shielded-e-g-for-Datron-1281-Agilent-3458A/263097836230?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2055119.m1438.l2649The cables look like selfmade.Has anyone experiance with that cables./PeLuLe

author: 0.01C
author_rank: Regular Contributor
timestamp: August 02, 2017, 05:34:54 pm
content: Great

author: pelule
author_rank: Frequent Contributor
timestamp: August 02, 2017, 07:21:08 pm
content: Hi Flintstone,stupid me, I was not able to link "ab-pr" at the bay with Adrian, wich I know personally.Thanks for getting me back on track./PeLuLe

author: cellularmitosis
author_rank: Unknown
timestamp: August 02, 2017, 11:21:48 pm
content: Quote from: 0.01C on June 18, 2017, 10:47:05 pmIt looks like that link goes to some vishay resistors. Can you post the link again? Thanks!

author: 0.01C
author_rank: Regular Contributor
timestamp: August 02, 2017, 11:28:14 pm
content: https://world.taobao.com/item/40823926055.htm?fromSite=main&spm=a230r.1.14.18.ebb2eb2u2gS1Z&ns=1&abbucket=7#detail

author: 0.01C
author_rank: Regular Contributor
timestamp: August 02, 2017, 11:35:40 pm
content: use chrome app to translate

author: cellularmitosis
author_rank: Unknown
timestamp: August 02, 2017, 11:37:37 pm
content: Ah, thanks for the tip.Do you also have a link to the banana plugs which are all one piece and have the cross-shaped cutout? I tried searching for those based on the description, but nothing came up.

author: EmmanuelFaure
author_rank: Regular Contributor
timestamp: August 02, 2017, 11:45:09 pm
content: $3.72 is for one piece?

author: cellularmitosis
author_rank: Unknown
timestamp: August 03, 2017, 12:04:29 am
content: Quote from: EmmanuelFaure on August 02, 2017, 11:45:09 pmYup.I've never been able to checkout successfully when using taobao directly (something seems to flag me at the captcha), but I threw 8 of them into my cart just to see what would happen, and lo and behold, it worked!I ordered 4 red, 4 black, for 200 yuan + 40 yuan shipping, which works out to about $3.72 each + $5.95 shipping.

author: 0.01C
author_rank: Regular Contributor
timestamp: August 03, 2017, 12:09:53 am
content: Quote from: cellularmitosis on August 02, 2017, 11:37:37 pmhttps://s.taobao.com/search?q=???&type=p&tmhkh5=&spm=a21wu.241046-us.a2227oh.d100&from=sea_1_searchbutton&catId=100

author: 0.01C
author_rank: Regular Contributor
timestamp: August 03, 2017, 12:11:03 am
content: oh , eevblog can not show the chinese word

author: 0.01C
author_rank: Regular Contributor
timestamp: August 03, 2017, 12:12:11 am
content: Quote from: cellularmitosis on August 02, 2017, 11:37:37 pmpm your email address to me , i send the taobao link to you

author: cellularmitosis
author_rank: Unknown
timestamp: August 03, 2017, 12:14:18 am
content: Yeah, that's a bummer! It just replaces the characters with '?'.

author: alm
author_rank: Super Contributor
timestamp: August 03, 2017, 01:00:27 am
content: I thought we solved this problem years ago with Unicode. But apparently Unicode is too difficult for SMF or the database setup.You might be able to use a link shortener liketinyurl.com/orgoo.gl.

author: cellularmitosis
author_rank: Unknown
timestamp: August 03, 2017, 01:08:16 am
content: I found two plugs which appear to be the same style (one solid chunk of copper with a threaded end):https://world.taobao.com/item/529066733817.htmhttps://world.taobao.com/item/550387066144.htmI've ordered a few of each. When they arrive, I'll cut into one of them (or try the citric acid trick) to see if they are really copper inside.

author: 0.01C
author_rank: Regular Contributor
timestamp: August 03, 2017, 01:40:14 am
content: Quote from: cellularmitosis on August 03, 2017, 01:08:16 amTry thishttps://world.taobao.com/item/36025097741.htm?fromSite=main&spm=a230r.1.14.19.ebb2eb27o1fGJ&ns=1&abbucket=17#detail

author: 0.01C
author_rank: Regular Contributor
timestamp: August 05, 2017, 02:34:45 pm
content: Looks pretty goodhttps://world.taobao.com/item/546621717699.htm

author: cellularmitosis
author_rank: Unknown
timestamp: August 06, 2017, 04:06:34 am
content: Quote from: Flinstone on August 05, 2017, 02:47:50 pmFred,My first experience was with a Taobao "agent" (it washttps://taobaofocus.com/), which is an english-language website where you give them the item numbers (from the taobao.com URL), and they buy the items and then ship it to you. This seemed convenient, but they tack on a ~30% fee, and then on top of that you have to pay rather expensive shipping (on top of whatever it cost to have the items shipped to them first). This meant that the salvaged LM399 references I found for ~$3.00 each ended up being the same cost as the ~$6.00 units available on ebay, which defeated the whole point of using taobao.Next, I used taobao.com directly. I used the translate feature of google chrome to mostly muddle my way through the sign-up process, and creating an alipay account (which is like a chinese paypal), shopping, and placing an order. There were a few screens which chrome didn't seem to be able to translate, and for those I had to install the google translate app onto my iphone, which allowed me to point my phone's camera at my laptop screen and perform the translation. Additionally, there are a lot of taobao listings which have text baked into images, which chrome can't translate, but the phone app can.In general, there's a very big "I have no idea if this is going to work" aspect to all of this, and you have to be willing to take a risk. For example, my first order was about 5 different items, 3 of which have shipped, and 2 of which have had no response from the seller in about 5 days (pity, one of those was an LT1088 for only $18 -- perhaps that was too good to be true).Best of luck!

author: cellularmitosis
author_rank: Unknown
timestamp: August 06, 2017, 06:19:32 am
content: Quote from: Flinstone on August 06, 2017, 06:16:01 amYeah, mine is linked to a Visa card.Not sure about what sort of protection they have. I'm actually discovering what ebay's process is right now -- I won an HP 3457A for $150, only to have it apparently delivered to the wrong address by fedex...

author: onemilimeter
author_rank: Frequent Contributor
timestamp: August 13, 2017, 04:32:55 am
content: Hi...I found this Teflon (PTFE) cable (shielded, silver plated, 19x0.2mm) from Taobao...https://world.taobao.com/item/525683103258.htmThe seller wrote it's imported from Japan, manufactured by Junkosha Inc (http://www.junkosha.co.jp/english/)The outer insulator (brown color layers) is Teflon/PTFE... but I'm not sure about the inner insulator (white color and black color layers)... if I buy it how can I test to tell if it's Teflon/PTFE?Thanks

author: cellularmitosis
author_rank: Unknown
timestamp: August 13, 2017, 09:17:51 am
content: I think you could use an electrometer to compare leakage against the same length of some CAT5. What is the most sensitive current range you have available on your instruments?

author: Andreas
author_rank: Super Contributor
timestamp: August 13, 2017, 09:22:29 am
content: why not make a simple test with a soldering iron.Teflon should withstand around 200 deg C.With best regardsAndreas

author: cellularmitosis
author_rank: Unknown
timestamp: August 13, 2017, 09:28:27 am
content: bigclive has an interesting way of testing finely stranded wire to see if it is actually copper, or just copper coated aluminum (which apparently is a common cost-saving trick in the ebay junk he loves to review). If you hold the flame of a lighter against the strands, copper coated aluminum will crinkle up like a dead spider, but pure copper is basically unaffected.

author: onemilimeter
author_rank: Frequent Contributor
timestamp: August 13, 2017, 11:39:06 am
content: Quote from: cellularmitosis on August 13, 2017, 09:17:51 amI may have access to a Keithley 2002. Can this instruments do the job? Thanks.

author: SeanB
author_rank: Super Contributor
timestamp: August 13, 2017, 11:52:27 am
content: Strip an end and use a lighter. If it burns it is PVC or some other plastic, and if it just chard and makes a noxious smoke it is PTFE.Likely though if the outer sleeve is PTFE the inner is as well, as that type of cable is common in avionics as a data wire or shielded cable for low level signals.

author: cellularmitosis
author_rank: Unknown
timestamp: August 16, 2017, 03:07:25 am
content: Quote from: cellularmitosis on August 03, 2017, 01:08:16 amWelp, the first set arrived. It looks like they are gold-plated brass, although they almost feel too light to be brass. (I filed off the outer plating, and the surface and shavings have the appearance of brass).I wonder if there is an easy chemical test to check for brass? I know that copper will turn some acids bright blue...

author: cellularmitosis
author_rank: Unknown
timestamp: August 16, 2017, 03:13:00 am
content: So after watching this Transmille video where he demonstrates using a null voltmeter to directly measure a thermal EMF, I decided to take the plunge and bought an HP 419A on ebay.https://youtu.be/KiYhEP6m7Pc?t=1m23sIn a few weeks I hope to be able to measure thermal EMFs directly!

author: 0.01C
author_rank: Regular Contributor
timestamp: August 16, 2017, 03:18:39 am
content: Quote from: cellularmitosis on August 16, 2017, 03:13:00 ambuy keithley 155 or Fluke 845 is better

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: August 16, 2017, 03:22:41 am
content: My money says it's brass. I am more interested in finding out what they used for the external plating.A null meter is invaluable and at least the seller gives a 14 day warranty. You may want to see what kind of chopper amp was used but I have recently taken photos of an ESI 801 and it used the HP 419 as the null meter. very nice looking inside.

author: cellularmitosis
author_rank: Unknown
timestamp: August 16, 2017, 03:35:16 am
content: Quote from: 0.01C on August 16, 2017, 03:18:39 amYeah, I did a bit of homework. Those are nicer units, but they are out of my "splurge" price range (they are $200+ on ebay at the moment).There are a lot of Leeds & Northrup models for ~$50, but their lowest range is 1mV.The 419A's lowest range is 3uV, and the price was right, so that's the one I settled on.(I think a fun project might be to see if you can get a Leeds & Northrup unit for $25 using "best offer", then gut it and install Conrad Hoffman's null detector circuit from his mini-metrology-lab article series)

author: cellularmitosis
author_rank: Unknown
timestamp: August 16, 2017, 03:40:19 am
content: Quote from: cellularmitosis on August 16, 2017, 03:07:25 amHmm...Quoteviahttp://ourpastimes.com/identify-brass-metal-8529918.html

author: cellularmitosis
author_rank: Unknown
timestamp: August 16, 2017, 03:52:48 am
content: Quote from: 0.01C on June 18, 2017, 03:36:28 pmGreat find! I've been searching for unplated copper spades, but haven't had any luck. Can you reveal a link to where you found these?

author: cellularmitosis
author_rank: Unknown
timestamp: August 16, 2017, 04:03:41 am
content: Quote from: cellularmitosis on August 02, 2017, 02:16:48 pmMy first victim to go into the citric acid bath was a cheap "logico" banana plug, which appear to be a clone of Nakamichi banana plugs.A few days into the acid, the body of the connector started to take on a reddish hue, and I thought they might actually be copper.However, after about another week, and after taking them out of the acid for a while, they were a much darker, brownish color. Filing away the body reveals what looks like brass.

author: cellularmitosis
author_rank: Unknown
timestamp: August 16, 2017, 04:54:44 am
content: I took interest in the "logico" plugs because I was trying to get away from plugs which had a loose-fitting free-spinning contact barrel-spring. The logico plugs were of a style where the contact spring was attached solidly to the body, which I thought would be better for precision measurements.Then, while searching for unplated copper banana plugs, I came across the plugs marketed at audiophiles:http://www.douglasconnection.com/Furez-TSTSB60NP-Bare-Copper-Banana-Plug-Connectors-Pair-FZTSTSB60NP.htmI liked the design of these plugs even better, as they were a single, solid piece of material, and it seemed there would be even more surface area in contact with the DMM's socket. They also claimed to be tellurium copper, so even though they are priced for audiofools, I decided to order a pair for use as a low thermal EMF "benchmark".Then, just this evening, I stumbled upon the fact that this style of connector has a name. If you search for "BFA banana", you'll find plugs like this.https://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Delectronics&field-keywords=bfa+bananahttps://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=bfa+banana&_sop=7https://www.aliexpress.com/wholesale?&SearchText=bfa+bananaTaking it a step further, you'll find plugs marketed as "low mass", which appear engineered to have a little mass as possible. This also seems desirable for minimizing thermal EMF's.I managed to find an ebay seller who sells unplated copper "low mass" BFA-style banana plugs, and I've just ordered a few. They are just under $3 each, so not cheap but also not audiofool-priced. I'll keep you posted!http://www.ebay.com/itm/162631332431

author: cellularmitosis
author_rank: Unknown
timestamp: August 16, 2017, 05:08:19 am
content: Here's a better shot, comparing the color of tellurium copper, the dark de-plated connector, a filed off section, and a "gold" plated original connector.(the red pliers, blue matt, and white paper are to help with white balance. capturing metal in a photo without turning it into a mess of glare is hard!).

author: MisterDiodes
author_rank: Frequent Contributor
timestamp: August 16, 2017, 02:49:12 pm
content: Just a head's up since this is metrology section: "Precision" connector as in chasing low ppm measures (if that's what you're doing) means no banana plugs; just use a -clean- direct wire connection to binding post whenever possible. The best low emf connections for low-ppm precision are clean copper to clean copper - or for easier cleaning the use of gold plated copper (typically will be gold flash over nickle over copper) connections are good also.Using a -clean- piece of solid copper wire slipped into the cross hole of a binding post really is relatively good "precision" connection and is considered better than any slip-in banana plug style. "Shrouded" banana plugs and sockets are not going to help low ppm measures.You'll see this inside a lot of null meters, and learn the manufacturing nuance: The inside connection to the binding copper post is usually a spade connector under a couple nuts on the threaded shaft (not soldered), usually gold plated and crimped spades. If you make the -same- type of connection with the same material on the external part of the binding post, you've basically cancelled most thermal EMF effect right there at one binding post (both end connections at the same post of same material combination at same temp cancel out thermal emf). Any other unbalanced thermal effect is greatly reduced by keeping the binding posts at the same temp.The general problem with something like a raw solid copper male banana plug is A) They always need to be cleaned of oxide before use and B) they are fairly soft, wear easily and tend to lose their spring-contact force - and that means it's harder to get a repeatable connection the more the connector is used. So that means you'll keep these for your more "special" setups, not for everyday general use.That's why for a general use: a good spring-rate brass alloy (with overplate nickel / tin / gold) is typically used for any connector requiring a spring force on the metal to metal contact area - that means longer contact life / more mating cycles.If you're using a plain copper banana plug, ideally that would slip into a plain copper socket - but that socket would be a bit harder to keep clean. The worst connection you could make for a "precision" setup is copper on oxide!The worst banana plugs for high precision repeatable measures would be the type with the loose spinning plug end - the solid style like you found is better.Those setscrews on the side of the banana plug are a place for problems to start especially if you're using stranded wire. Keep an eye on that. Wire strands have a really bad habit of wiggling out from under setscrews, and if these leads would see a lot of use we'd use a copper ferrule crimped onto the stranded wire wherever it's going to be under simple screw clamps like that.

author: cellularmitosis
author_rank: Unknown
timestamp: August 16, 2017, 06:17:46 pm
content: Thanks MisterDiodes, that's great advice.My hunt for the perfect banana plug is in an attempt to solve the budget metrologist's problem of "my best meter has banana sockets, not binding posts". That budget metrologist will never be able to achieve a "perfect" setup, but given that, the question is "how close can they get?".For example, the 34401A (if you can find one under $250) represents a very good bargain for the budding volt-nut, but sadly, only comes with banana sockets. In spite of that, the budding volt-nut is someone I want to support in their quest, and hopefully I'll come up with some useful findings!

author: pelule
author_rank: Frequent Contributor
timestamp: August 16, 2017, 07:34:52 pm
content: Just a may be stupid question about thermal EMF at the 6.5 digit voltmeters 34401A:Lowest DC voltage range is 100.0000 mV @ 0.1µV resolutionBut best accuracy is +/-3µV +/- 0.5uV/°C plus the reading error.ref data sheet, 24 hour accuracy: 30ppm (reading) + 30ppm (range) + 5ppm/°C (reading) + 5ppm/°C (range)So in my understanding the thermal EMF is not the biggest issue here./PeLuLe

author: MisterDiodes
author_rank: Frequent Contributor
timestamp: August 16, 2017, 09:04:57 pm
content: Good point about 34401. But remember Cellular has his null meter coming, which will lead to a much better Keithley 155 / Fluke 845a / or ?? + 7-decade KVD plus some 732's also. He's got the infection, which means he'll be very broke (but very accurate on DCV measures) in no time.Even a good working 3456a will get you nice & stable, low noise 6.5 digits measure if you have the space for one - and they are cheap & easy to keep in cal. Nice units.There's a reason meters with recessed banana plugs don't make it into the cal room. For one of our clients The Tek / Keithley sales guy got so frustrated and desperate a few years ago they caved in and supplied some custom-modified meters with good binding posts... so it does happen if a larger order is possible.

author: Echo88
author_rank: Frequent Contributor
timestamp: August 16, 2017, 09:17:23 pm
content: Why dont they supply >= 6.5 digit DMMs with binding posts as a standard? Beauty-reasons?

author: MisterDiodes
author_rank: Frequent Contributor
timestamp: August 16, 2017, 09:25:49 pm
content: Mostly companies working with Gov'ts trying to regulate in safety arc-flash specs and various CAT-level instrument ratings... Which is certainly OK if you're working in that environment, but not so good for low ppm work.

author: cellularmitosis
author_rank: Unknown
timestamp: August 16, 2017, 10:15:03 pm
content: Hmm, perhaps I am barking up the wrong tree? I.e. Perhaps I should instead be investigating how best to hack some Pomona 3770's into it? Couldn't hurt -- even if I botch it, i still have a rear set of inputs!Although, chasing after low EMF bananas is still useful from an inclusion perspective -- for ensuring that the widest audience of budding volt nuts can participate (I can't expect everyone to hack their meter).Mr Diodes, you have me nervously laughing. I have made a few additional purchases recently which I haven't even revealed on the forum yet. Cash poor but D.C. accurate does seem to be the prognosis...

author: MisterDiodes
author_rank: Frequent Contributor
timestamp: August 16, 2017, 11:53:59 pm
content: The other trick is to make or buy an adapter board that brings out those child-safe recessed banana sockets to dangerous binding posts... Male plugs on one side, binding post on the other. There are photos on EEVblog...It is not unheard of in the lab is just bypass those stupid shrouded sockets altogether and solder wire direct to the input section of the meter - then you just snip a little wire off the free end for new experiments, and replace the wire now and then. Not exactly elegant I know - but do what you have to do...None of this is a huge issue for 34401 but you'll get there with more sensitive experiments and other setups, especially with a null meter. Once you play with a 3uV scale null meter, then you can get some time on a 1uV or smaller scale meter, and you can move the needle with your eyes only... Not really but that's what it seems like sometimes. You can see the effect of just the heat of your hand on one side of the connection.For now you'll have fun and learn a lot in the world of null meters... You can play with the null meter and find out how connections work (or not). You'll probably find out that if you use the same type of connection on both ends of a binding post you'll get pretty good results.Don't forget when you do a null measure between two voltage sources with that meter, get everything zeroe'd out...and then reverse the connections. Make a change on a voltage source of that difference divided by 2. Keep doing that until the needle is pretty steady even when you flip your connections around and then that's your compensated null point that is relatively free of thermal emf. You'll need a stable voltage source and a KVD now also <Grin>. You don't need that retirement fund do you?If you're measuring just a connector with that meter you can get your experiment setup and meter zeroed out, then heat one side of the connector only. Then flip the connections around and try again, and that will show you what's really happening at the connector itself. Fun stuff!

author: quarks
author_rank: Frequent Contributor
timestamp: August 17, 2017, 08:30:01 am
content: Quote from: MisterDiodes on August 16, 2017, 11:53:59 pmabout adapters have a lookhttps://www.eevblog.com/forum/testgear/lking-for-gold-plated-tellurium-copper-banana-plugs/msg246371/#msg246371https://www.eevblog.com/forum/testgear/lking-for-gold-plated-tellurium-copper-banana-plugs/msg327291/#msg327291

author: cellularmitosis
author_rank: Unknown
timestamp: September 07, 2017, 11:49:42 pm
content: Quote from: Echo88 on August 02, 2017, 12:34:45 pmEcho88, I've replicated your results using citric acid. I just cut up a few pieces of some cheap crimp connectors as a test.If I recall, this was 60 grams of water, and 12 grams of citric acid powder (i.e. 20% by weight).I got lazy about removing them, so they were in there from 8/16 through 9/6, but they were mostly stripped after about 7 to 10 days. You do need to agitate them to ensure all surfaces are exposed to the acid, daily agitation would be good.(the large welding cable connector is just for color -- it came as bare copper from the factory and is used as a color reference only).

author: cellularmitosis
author_rank: Unknown
timestamp: September 07, 2017, 11:54:59 pm
content: Next into the bath: some 1/4 inch spade connectors (Morris #11520) from amazon.com. These are the right size to accommodate e.g. a pomona 3770.Unfortunately, the crimp loop was a bit larger diameter (16-22AWG, or 1.25mm) than I'd hoped for (I'm hoping to be able to crimp to a single CAT5 strand directly). I can probably use a hammer, punch, and anvil to do the job.See you in a few weeks!Hrmph, it appears these are already "no longer available" on amazon.Here's a google shopping search. They are available for $13 / 100 pack:https://www.google.com/shopping/product/14631136190881433596?rlz=1C5CHFA_enUS708US708&biw=998&bih=1454&q=Morris+11520+spade&oq=Morris+11520+spade&sa=X&ved=0ahUKEwiMn83lppTWAhVkl1QKHTuZCNEQ8wIIvwEwAA

author: cellularmitosis
author_rank: Unknown
timestamp: September 08, 2017, 12:06:31 am
content: It turns out these connectors follow a naming convention, e.g. SNB1.25-6, OT2-4, UT1.5-3, etc.SNB, OT, UT describe the kind of connector (fork vs ring, both SNB and UT appear to be forks, OT appears to be a ring).The first number describes the diameter of the crimp opening (e.g. 1.25 mm).The second number describes the fork / ring opening clearance (-6 is 6.2 mm, about 1/4 inch).You can find these by the thousand pack for under $10 on alibaba and toaboa, but at those prices they are likely to be brass rather than copper.I find it hilarious that unplated copper connectors sell at a crazy premium compared to tin-plated-copper connectors. In theory, they should be cheaper (one less manufacturing step).The size we want (to accommodate a pomona 3770) is the 1/4 inch stud (-6), and for crimping to CAT5 / telephone wire, I think you'd ideally want a 1mm crimp opening, so you're looking at either SNB1-6 or UT1-6. Domestically, the closest I've been able to find is SNB1.25-6 (this is the size of the Morris #11520 connectors).I have seen UT1-6 available on taobao, but copper vs. brass is going to be luck of the draw there, and minimum quantity will likely be a bag of 1000.

author: manganin
author_rank: Regular Contributor
timestamp: September 08, 2017, 08:28:31 am
content: Quote from: cellularmitosis on September 08, 2017, 12:06:31 amBut there are also honest sellers:Quotehttp://www.ebay.com/itm/311026743780

author: SZA263
author_rank: Contributor
timestamp: September 08, 2017, 11:31:31 pm
content: Try also this:http://www.tme.eu/gb/details/bm01132/non-insulated-terminals/bm-group/bm-01132/

author: cellularmitosis
author_rank: Unknown
timestamp: September 09, 2017, 12:15:50 am
content: Quote from: 0.01C on August 05, 2017, 02:34:45 pm0.01C, these arrived today, and they in fact are solid copper.

author: cellularmitosis
author_rank: Unknown
timestamp: September 09, 2017, 12:28:04 am
content: With these (and a few other items), I discovered a little hitch in the taobao game.Some sellers will ship the items directly to you. When this happens, you just pay once, and you know the total cost up-front.Other sellers ship the item to some sort of exporting warehouse. So the amount you are paying upfront isn't the total cost -- a few days later you get hit with additional shipping charges, and they seem to be fairly expensive. Unfortunately, I haven't been able to figure out a way to detect which situation will happen ahead of time.In this case, the binding posts which look like a copper pomona 3770 clone were shipped directly to me, and the cost was known up-front. But with these latest bare-copper binding posts (which don't have banana jacks), I got hit with an additional $13 shipping charge, which made the other posts a bit of a better deal.The copper pomona 3770 clones ended up $36.77 for 8 posts (about $3.83 each plus $6.13 shipping), making them effectively$4.60 each.https://world.taobao.com/item/40823926055.htmThese most recent bare-copper posts were $33.11 for 10 posts (about $2.85 each plus $4.63 shipping), but with an additional $13.13 warehouse shipping charge, making them effectively$4.62 each.https://world.taobao.com/item/546621717699.htmI don't want to paint a rosy picture of taobao -- so far I've paid for two items which haven't arrived in over a month (a few cheap banana plugs, but also a pair of LT1088 chips which were $18 each, ouch!) -- likely I just got scammed.

author: 0.01C
author_rank: Regular Contributor
timestamp: September 09, 2017, 01:39:38 am
content: Quote from: cellularmitosis on September 09, 2017, 12:28:04 amfor your referencehttp://www.howtotao.com/buy-from-taobao/https://world.taobao.com/item/45907925781.htmhttp://www.taobaoguides.com/2016/07/06/the-best-way-to-ship-taobao-packages-from-china-to-usa-and-eu-countries

author: cellularmitosis
author_rank: Unknown
timestamp: September 09, 2017, 07:53:03 pm
content: Quote from: MisterDiodes on August 16, 2017, 09:04:57 pmSo it turns out MisterDiodes can predict the future...Edit: derp, wrong picture

author: branadic
author_rank: Super Contributor
timestamp: September 13, 2017, 07:52:24 pm
content: A question to those that are familiar with the topic. Is it really necessary that the outer insulation is PTFE too? I foundcable for RTDs, with PTFE insulation on the single wires, 4 wires twisted and shielded, but with PFA for the outer insulation. So the question is, does it really make any difference if the outer insulation is non PTFE?-branadic-

author: The Soulman
author_rank: Super Contributor
timestamp: September 13, 2017, 08:15:59 pm
content: Quote from: branadic on September 13, 2017, 07:52:24 pmYou do the math,it's on the outside of a braided shield.Here is something that could belong here, a quote from myself from the ltz1000 thread but didn't get a reply there so re-post it here:Quote from: The Soulman on August 22, 2017, 01:38:44 pmThis low thermal connections are very important for accurate readings, but is starting to smell like some audio related behavior.

author: Edwin G. Pettis
author_rank: Frequent Contributor
timestamp: September 13, 2017, 10:59:54 pm
content: "This low thermal connections are very important for accurate readings, but is starting to smell like some audio related behavior."The answer is that thermal EMFs, usually in microvolts, becomes important when attempting to accurately measure PPM, at lower accuracy, say ~25PPM or higher, the thermals becomes less important as they are a proportionately smaller than the measurement's signal value in general. In practice it is a good idea to minimize thermal EMFs at all times as they represent an uncertainty factor in the measurement which can vary. For example, a resistor with ±.0025% tolerance, a couple microvolts of thermals aren't very important, at ±.001%, now they've become significant as they could represent 2PPM, 3 PPM or more of error, a null meter is the best instrument for detecting this.PPM measuremenvts are almost always at microvolt or lower potentials so thermal EMFs become very important, they are not part of the audiophoole mythology.

author: MisterDiodes
author_rank: Frequent Contributor
timestamp: September 15, 2017, 12:00:29 am
content: Quote from: cellularmitosis on September 09, 2017, 07:53:03 pmYou thought I was kidding...I hope your '845 works well, these nullmeters will open up a new low-ppm world of discovery for you. Be patient with it at the low end though...What you think is the needle floating around at 1uV and 3uV range is probably a thermal somewhere in your setup....There will be plenty of that.

author: BU508A
author_rank: Super Contributor
timestamp: September 15, 2017, 06:20:55 am
content: Hi branadic,Quote from: branadic on September 13, 2017, 07:52:24 pmIn my opinion: no. There are two or three main reasons, why using PTFE:- high insulation resistance- heat resistance- low dissipation factorhttps://www.druflon.com/ptfeprop.htmlFor the outer insulation, PFA is very fine.Good example: inner insulation: PTFE, outer insulaton: FEP (cable is RG 400 U)http://www.ebay.com/itm/162634086255Andreas

author: BU508A
author_rank: Super Contributor
timestamp: September 15, 2017, 06:42:57 am
content: I just stumbled over this page:https://goo.gl/kfkKWN(link goes to google books and sorry the site is in german. But the table shown is interesting, chapter 0.2.3.9).Does this table suggest, that a smart combination of copper, silver and gold will give you some kind of compensation effects?All metals were paired to copper.from the table:thermal emf copper - gold: +0,1µVthermal emf copper - silver: -0,2µVThanks,Andreas

author: Echo88
author_rank: Frequent Contributor
timestamp: September 15, 2017, 09:57:58 am
content: There is no smart combination of different metals to compensate for thermal emf, instead:-just use the same batch of copper wire for your whole construction,-crimping instead of soldering,-where soldering cant be omitted use symmetrical components to cancel the resulting thermal emf between copper-solder-keep the whole construction isothermal/couple all your measurement stuff thermal tightly.The Keithley 147/148 and all other low thermal emf devices can be used as a good example how to do it.Another way of thinking: To efficiently use different metals to cancel thermal emf youd have to knew the exact temperature distribution across your construction in extremely high resolution, which isnt possible i think. At least i dont know if its ever been done in this way and no thermal emf equipment manual ever suggested doing it your way.

author: branadic
author_rank: Super Contributor
timestamp: September 15, 2017, 02:02:43 pm
content: Hi,I wonder which diffusion barrier is used when gold is plated over copper. Nickel seems to be a bad idea, but does it really influence to measurement? It's only a few nm of thickness.Is it just galvanic gold without diffusion barrier in between? What about copper-palladium-gold? Any ideas?-branadic-

author: MisterDiodes
author_rank: Frequent Contributor
timestamp: September 15, 2017, 05:43:10 pm
content: Of all the connections, clean copper to clean copper is overall best - but does have it's practical limits because it has to be kept clean. A gold plate, thick enough to not wear quickly is a good choice that does add a slight amount of noise, but very small. "Low Thermal" brand has that construction - gold directly onto copper, and thick enough. Gold over nickel can be used also without too much ill effect and you can get away with a thinner gold flash. Never had a huge problem with nickle sub-plate in our setups, and we've never had a problem with direct gold over copper (when the gold is thicker, say 50u"). A very thin (cheap) gold flash directly on copper is not the best.As for insulation, also consider EFTE wire - a cousin to Teflon but much stronger and higher dielectric strength, very slightly less volume resistivity (10^17 vs 10^18). We use this stuff a lot and also the Conetic braid and flex conduit for precision measures that need good mag shielding and tough enough to hold up to daily use:http://custommagneticshielding.magneticshield.com/viewitems/magnetic-shielding-for-wiring-applications/inter-8-weave-cableRemember that noise can be coming in to your DUT on that sometimes dirty power mains ground, so pay attention to how you use / or don't use that - and use a clean quiet dedicated lab "ground" reference as required. Keep your test leads twisted and short - and remember that the moment you connect those leads to your circuit then your instrument and all the ground loops in between now become part of the whole system measured noise.

author: martinr33
author_rank: Frequent Contributor
timestamp: September 16, 2017, 06:28:35 pm
content: Other than that tricky noise point, plating layers don't matter too much. What does matter is that the final layer is low thermal relative to the base layer. The thermoelectric voltages are largely balanced across the layer: most of a copper-nickel junction voltage is canceled out by, say, a nickel-gold junction on the other side, leaving the copper-gold voltage as a residual. Of course, that assumes that both sides of the layer are at the same temperature, which is OK if the layers are thin.Where we have a bigger problem is across the terminals. The jacks themselves can get quite warm, and any temperature differential here will expose thermoelectric voltages at the jacks.I think that my meter jacks are gold plated, so I am facing gold no matter what..

author: MisterDiodes
author_rank: Frequent Contributor
timestamp: September 17, 2017, 12:43:35 am
content: Quote from: martinr33 on September 16, 2017, 06:28:35 pmNone of that matters much as long as you've got the same combination of material balanced throughout your circuit. Your binding posts are mounted on a good thermal conductor panel (not plastic) - that helps them stay at the same temp. You're not using banana plugs, you're using a direct clamped wire or crimped spade / ring at the front of the panel to match the (usually) crimped ring connection on that binding post behind the panel (posts usually not soldered behind the panel for precision equipment). Keeping those nuts snug helps keeps those joints in better balanced thermal contact with the panel surface. That doesn't work as well with banana plug systems - especially the shrouded types.Keep everything balanced and as close to the same temp as possible and you should be getting some repeatable measures.Don't forget - if worse comes to worse you get rid of the binding posts and go for a direct connection...but that's a story for another day.

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: September 17, 2017, 10:44:20 pm
content: On the matter of the teflon 'cables' many of you seem to use:most of the material seen here are technically not cables, but hookup wiring material.I enclose the supplement which contains the overview of the sub-standards for the most common type of such wiring material, which is MIL-W-22759. A manufacturer's designation is for example Raychem Spec-55.As you can see from the document, this comes in copper and copper alloy as base material and in several different platings (silver, nickel, tin).And the standard as well as the commercial implementation does cover twisted pairs, shielded twisted pairs and shielded quads. The shielded versions have a outer isolation layer over the shield, which does not yet make them a cable in the formal sense.There was also a series by Raychem called Spec-99, which used extra-fine stranding. Some of the nicest, most supple isolated wire that i have encountered. Unfortunately, only made to order.Maybe this helps when when obtaining surplus PTFE/ETFE material.

author: cellularmitosis
author_rank: Unknown
timestamp: September 19, 2017, 03:49:04 am
content: Welp, the citric acid progress seemed to stall out, and after about a week I got impatient and picked up some muriatic acid at the hardware store.A word of caution: this stuff is scary strong. Only use this outdoors, wear gloves, don't breathe the fumes, and have a gallon of water and a box of baking soda within reach at all times. Use a pipette or turkey baster to transport the acid -- don't try to pour the bottle!Initially, the reaction was quick and vigorous -- the outer, shiny coating bubbled and was stripped in about 15 minutes. This left a very dull, darker gray inner layer, which took about 40 hours to completely dissolve and reveal the copper.I may need to lap these smooth, as the acid leaves a matte finish with high surface area (which will make slightly inferior thermal contact and will invite oxidation faster).Off the top of my head I'd say the end result is about $0.34 per connector (~$14 for the connectors, ~$15 for the acid, ~$5 for baking soda).Neutralizing the acid took a while. By spooning in a teaspoon of baking soda, and then waiting for the foaming to die down, then repeating, it took me about 10 minutes (and probably 1/3 of the box of baking soda) to neutralize about 1/2 cup of acid.

author: lukier
author_rank: Unknown
timestamp: September 25, 2017, 02:37:18 pm
content: I've ordered a bunch of these copper binding posts (https://world.taobao.com/item/40823926055.htm), but it seems I did something wrong on Taobao - should learn more languages.The order was paid correctly (VISA), including the shipping (2 x 40 yuan for that) and sent by the seller but the parcel is still in Shenzen for the last two weeks (LX480192824CN).Did anyone encounter the same problem?

author: CalMachine
author_rank: Frequent Contributor
timestamp: September 25, 2017, 04:50:34 pm
content: Procured some parts to make a cable for older Keithley NanoVoltmeters (180,181,182). There are other models that use the same type of military style connector, as wellConnector - AIT6E16-11PC-B30 (Gold Plated, Copper Alloy, Crimp connection)Cable - Belden 5500FE (~1.5m)Spades - Bare copper crimp spadesI could have gotten a bare copper version of the connector... But, that isn't a normally produced item and would have been made-to-order with a MOQ, which I would have been no where near close to.Short values are compared with the K1488 Low Thermal shorting plug. Only ~130 nV deviation from the plug leaves me very satisfied with this cable

author: 0.01C
author_rank: Regular Contributor
timestamp: September 26, 2017, 02:49:48 am
content: Quote from: lukier on September 25, 2017, 02:37:18 pmI just send your message to the taobao seller , you can file a item not received case on taobao to get full refund.

author: 0.01C
author_rank: Regular Contributor
timestamp: September 26, 2017, 03:00:48 am
content: Seller reply your item is on the way now , the tracking detail update very slow ,please wait some more days

author: 0.01C
author_rank: Regular Contributor
timestamp: September 26, 2017, 03:07:55 am
content: Seller will reply you here

author: Squantor
author_rank: Contributor
timestamp: September 26, 2017, 07:44:17 am
content: Quote from: CalMachine on September 25, 2017, 04:50:34 pmWhere did you get the AIT6E16-11PC-B30 from? I have been looking for a solution for my Keithley 150B for ages.

author: lukier
author_rank: Unknown
timestamp: September 26, 2017, 07:48:36 am
content: Quote from: qinchang on September 26, 2017, 02:43:29 amQuote from: 0.01C on September 26, 2017, 03:00:48 amThanks guys, it is some strange glitch with the tracking.Unfortunately, Wangwang Chat in the Chrome browser never worked for me and the standalone client is only for Windows, so I couldn't contact the seller.

author: 0.01C
author_rank: Regular Contributor
timestamp: September 26, 2017, 07:11:10 pm
content: Quote from: lukier on September 26, 2017, 07:48:36 amyour item is arrived in the UK.

author: lukier
author_rank: Unknown
timestamp: September 26, 2017, 07:46:37 pm
content: Quote from: 0.01C on September 26, 2017, 07:11:10 pmYup, just today. Thanks! Just normally there are some tracking events in order, like post office received, transit, airport arrival, leaving airport to overseas etc before it reaches Heathrow. Lack of any extra events and tracking saying the parcel is still in Shenzen got me worried.Thanks again for all the help. Hopefully Duolingo will introduce Chinese soon, so I can learn a bit

author: CalMachine
author_rank: Frequent Contributor
timestamp: September 26, 2017, 08:17:46 pm
content: Quote from: Squantor on September 26, 2017, 07:44:17 amIt is an Amphenol MS3106E16-11P connector and the gold plated/copper crimp version is the part number I listed (AIT6E16-11PC-B30).The local distributor I used is PEI Genesis. You might need to get ahold of Amphenol and find out who your local distributor is.

author: branadic
author_rank: Super Contributor
timestamp: September 30, 2017, 11:39:46 pm
content: Sorry to hack this thread, but maybe someone in here can help. Were can I get those securitygold plated copper postsused in many multimeters such as Keithley, Prema and so on? What I found up to now is always gold plated brass, but I'm pretty sure Keithley won't use brass in their 2002 model, do they?I need them for a low thermal emf, low noise application (2x black, 2x red). Thanks for your help.-branadic-

author: lukier
author_rank: Unknown
timestamp: October 01, 2017, 12:03:52 am
content: Quote from: branadic on September 30, 2017, 11:39:46 pmSecurity banana sockets and low-EMF don't usually go hand in hand.I too couldn't find the particular ones used by Keithley, gold and with the pin-sleeve mount on the back. This one looks the most similar in shape and form, but it is brass+nickel:http://www.caltestelectronics.com/ctitem/91-jacks-banana-jacks/CT2912If you don't need the Keithley like connectivity on the back and this is for one-off project I would recommend buying 34401A input block part from Keysight (part number 34401-62121). Not crazily expensive and you get five tellurium copper banana sockets, going straight to the PCB.

author: The Soulman
author_rank: Super Contributor
timestamp: October 01, 2017, 09:43:19 am
content: Hirschmann has those: (gold plate over brass)https://www.reichelt.com/de/en/4mm-Jacks/SEP-2630-S19-SW/3/index.html?ACTION=3&LA=446&ARTICLE=130849&GROUPID=5629&artnr=SEP+2630+S19+SW&SEARCH=hirschmann%2BgoldI did ask before but will ask again, how does the base material matter at all (for sub micro Amps) if the gold plate is all around?

author: Echo88
author_rank: Frequent Contributor
timestamp: October 01, 2017, 10:03:33 am
content: He did ask for gold plated copper ones, not brass. And this matters for very high accuracy voltage measurements because of the thermal emf voltages generated by the jacks. All the electrons flow through the volume of the jack, not on the gold plated surface, therefore copper as base material is necessary.

author: VK5RC
author_rank: Unknown
timestamp: October 01, 2017, 10:15:33 am
content: The Pomona 3770 is a nice multiway post at not crazy money, gold plating over tellurium copper, pure copper is almost unmachinable and soft I believe.Au Mouserhttp://au.mouser.com/ProductDetail/Pomona-Electronics/3770-0/?qs=yih5jomMvb3Uhbdu3XO%2FAg%3D%3DData Sheethttp://www.mouser.com/ds/2/159/d3750_60_70_1_01-34263.pdf

author: branadic
author_rank: Super Contributor
timestamp: October 01, 2017, 11:04:38 am
content: I do know the Hirschmann gold plated brass things (have them on my desk) and I do know the Pomona multiway posts (have them on my desk too), but for some optical design reasons they are not the perfect choise, but I do want the gold over copper configuration for low noise and low thermal emf. So that's is why I asked if someone knows where to get the Keithley or Prema single banana socket jacks. The Agilent banana block is nothing I can use in my application.-branadic-

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: October 01, 2017, 12:33:22 pm
content: Has anyone tested the Keithley jacks to see if they are gold plated copper? They could be brass and depend on the internal meter temp to keep thermals balanced.The only way I know of to get them is to order a replacement front panel. It isn't cheap but if you have a Keithley meter needing a shiny front cover, you would just recover the old ones.In the end, the Low Thermal binding posts would be cheaper but still not what you want. The Low Thermal posts are ~$25US/ea and much better quality than the Pomona 3770.

author: Echo88
author_rank: Frequent Contributor
timestamp: January 07, 2018, 04:39:12 pm
content: I see there are many copper binding posts and spade lugs here listed, but are there any known gold plated copper binding posts available which are cheaper than the Pomona 3770 / where to get gold plated copper spade lugs? I dont like to use non-plated lugs/posts because of the oxidation hassle and for my reference-voltage-switch its not necessary.Maybe someone has a Data Proof-scanner binding-post-backside which he wants to sell?

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: January 07, 2018, 05:16:51 pm
content: The 3770 is as low cost as I have found. Mueller makes them with a similar part number but the reported quality is not the same as Pomona.On my reference array, I use bare copper and I would suspect others here do the same. Sometimes you can't get away from bare copper if you are measuring in the nV range.Also, my Data Proof scanner is the model with wires and not binding posts so there is only the end at the reference that needs to be terminated. The cable is simple unshielded phone cable.

author: Echo88
author_rank: Frequent Contributor
timestamp: January 09, 2018, 02:29:18 pm
content: You are right, the necessary costs for a 16-channel 4-wire binding post-scanner are not justifiable. Therefore i will also use wires. But if im using solid-core-wire: does it tarnish after some time even under the clamped binding-post section and accordingly begins to produce high thermal emf-voltage?

author: dl1640
author_rank: Regular Contributor
timestamp: January 19, 2018, 03:59:45 am
content: Quote from: MisterDiodes on September 15, 2017, 05:43:10 pmi did see our Wavetek 1271 give unstable reading once it was plugged into a power strip with a "dirty" ground.the cause was the power strip itself didn't has a good ground receptcle, spring is not holding the ground pin of the power cord, tightly.it was not thermo emf which cause such instability.i suppose the ground of the mains is going to the breaker panel,and the dedicated lab ground should be going to the earth directly.however i feel it very difficult to ensure which ground is more effective.as many hi-end instrument like 3458 and 5700 has a optional grounding post just nearby the power inlet,is it a good idea to connect a gound wire from this grounding post to the lab ground (earth) and also the mains ground is connected to the instrument's power inlet?make sense?sorry this is off this thread subject in a way.i'd like to hear some advice and learn something.thanks!

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: January 19, 2018, 04:06:50 pm
content: Quote from: dl1640 on January 19, 2018, 03:59:45 amIn most parts of the world it is mandatory to connect the grounding conductors together in a controlled fashion (equipotential bonding). Having your electrical supply in your lab grounded locally only would be definitely detrimental to safety. It is viable only for the operational (RF) grounding of antennas, but even there a connection to the ground system (via a spark gap or without, depending on electrical codes) is necessary. Of course, you can improve the grounding for a lab by having a better earth system, but this means setting up a local grounding rail, where you connect them again. To keep out RF via ground, use a ground choke.

author: MisterDiodes
author_rank: Frequent Contributor
timestamp: January 19, 2018, 06:46:09 pm
content: Of course a quiet "local" lab ground that is not run in the mains conduits is superior even down to DC - but that doesn't mean it's not safety bonded to the utility company power source -outside- the lab. Keep it safe.A ground choke and good noise cancling toird transformers will certainly help quite a bit but at low frequencies we've always seen additional noise improvement using a dedicated lab ground, generally using a very wide bandwidth braided cable (lightning rod #1 down-lead in safety shield) leading to a good outside heavy ground connection. Now the lab has a pristine, un-shared, safe and unpolluted connection to Mother Earth.The new lab buildings are even spec'd that way from the ground up (pardon the pun) and meets all building code requirements.The whole point is to keep power mains induced ground currents and Voffsets out of the equipment under test - and if there's any question look carefully and the induced currents that are generated on the ground conductor in a typical mains power conduit entering the lab, at low freq. The problem is worse if you have heavy equipment on your side of the building's utility co. transformer.The required (for us) steel mains conduit itself becomes a random 1 turn coupling transformer into the utility ground...You'd think that the random twisting of the mains conductors would reduce the effect - and it does to some extent - but by the same token it doesn't -perfectly- cancel out, because the wires are never twisted perfectly in a balanced fashion.You get an even greater coupling effect if the mains power cables are strapped to a steel girder or building support - and at heavier current flows you'll see more junk noise cosstalked into the utility ground wire.In other words: Watch your mains wiring and see we're you've got accidental built-in UN-balanced coupling transformers - then you see why a dedicated lab ground helps keep measurement noise lower.

author: dl1640
author_rank: Regular Contributor
timestamp: January 20, 2018, 08:04:15 am
content: hi neomys and mr.diodesof course most instruments are plugged into 3-prong mains outlet (with ground), and instrument manufacturer require to do so, this is for human safety. after a brief search there are several national codes talking about electical system grounding and i will study them.our lab very small, just one room. but it do have seperate ground facility apart from mains ground. this lab ground is running of a copper bar around the room, at first the purpose of this facility is to discharge electro-statics through a hand strip.the problem is i cannot tell if this lab ground is better than the mains ground. if a instrument is connected to both ground, would that be another ground loop?

author: MisterDiodes
author_rank: Frequent Contributor
timestamp: January 20, 2018, 06:49:14 pm
content: No, don't use multiple ground points.What you want to look at is study the isolated ground / dedicated ground techniques used in every modern hospital, serious R&D labs near wafer fabs, and anywhere high precision measurements are done, and you need to keep your measures low noise even though there might be heavy, noisy current flows on the building power mains cables.Think of the "IG" (Isolated Ground) or DG" setup (dedicated ground which is similar except uses a relatively large ground conductor compared to what is normally called for) as a Star Ground connection system where you have a very good single ground connection to Earth, and that is a common Earth bond point between your lab, utility power source and mains distribution protection system. When I say a "dedicated lab ground" that is essence a larger, very low impedance cable leading from your test area back to the very good common bonded ground point outside of the lab room - for instance where you have -multiple- ground rods installed for the mains power system entering the building.The concept here is that for sensitive equipment you're NOT using the relatively high impedance, noise-coupled copper wire that runs along side the mains cables to make your ground connection - with a DG you're using a good heavy conductor that takes it's own low noise path to the COMMON very low resistance ground point....and you DON'T want to run that ground DG cable along side the normal high-noise mains wiring.You can still have a common ground bus bar on the test bench like you have but that would be connected to your isolated / dedicated ground conductor (ALONG WITH YOUR "IG" rated equipment sockets) - which is the good heavy conductor that does NOT run along side the power cables. You are still safely connecting back to the bonded utility ground point - just in a low-noise way.On some systems where shielded isolation transformers are used, the transformer primary section uses the standard utility ground wire on the power plug, but the inter-winding shield and secondary side uses the isolated & dedicated low impedance ground system.Generally (as required by law for certain commercial buildings) there is also a grounds circuit monitor system in place that will instantly trip off the mains power (or sound an alarm) in case a safety grounding system goes open for some reason.You never want to create a "floating" ground situation - that is where you have a ground system that is completely disconnected from the utility / power source ground. That creates a situation where if you have an equipment failure where a utility mains "hot" circuit can energize the outer cabinet of a piece of equipment - and the mains circuit breaker or GFCI never trips...that's bad. Don't ever let that happen. You always need to look at your setup and guarantee that the basic testing setup poses no danger to the equipment operator. If there is a human contact hazard by the nature of the setup, then that situation needs to be clearly labeled, and perhaps lockouts, safety interlock switches on cabinets and/ or requirement that Personal Protection Gear be worn. At least here in the States that is usually a strict issue with insurance companies and the annual fire / safety code inspectors.It just depends on the safety / grounding situation and what voltage / energy levels you're looking at. Usually we never even think about this when testing low voltage, low power circuits < 50VDC - but when you start taking precision measurements at higher voltages - it doesn't take more than one hard accidental "bite" to realize you need to keep your grounding system safe and low-noise.EDIT: In the final analysis: Your most sensitive gear on the lab bench would either get power from isolation transformer or plug directly into IG type mains sockets, and those IG's are grounded to your heavy bench ground bus bar and low impedance DG cable, which in turn runs back to the common utility-bonded grounding point. That makes everything on your test bench sitting at -one- single common reference point.Your lab lighting loads, outlet boxes, conduits and mains raceways, motors etc. would still be grounded the standard way.NOTE: You will see some info on the 'net talking about how "IG" systems sometimes don't work well, usually written by non-metrologists who don't normally measure down in low ppm - but the difference here is that on high performance systems you're using a very high performance, heavy grounding conductors - not the piddly little noisy mains wire electricians refer to as the "ground wire". If you're chasing ppm, you want a test bench system ground setup that has much lower noise & impedance ground than you'd find in a typical wiring setup.

author: dl1640
author_rank: Regular Contributor
timestamp: January 21, 2018, 03:12:34 am
content: Thank you Mr Diodes for giving so much.I need some time to study your comments and our real situation.An 17025 auditor once insisted that our 5700A calibrator MUST be grounded at both mains ground and Earth (rear binding post mounted on chassis) which very much frustrate me. I quote what he said “Your mains ground is going a long way to utility company’s transformer there is attenuation along that way.” Today I suppose he means the mains ground might be dirty. And we have no record/document to prove either mains ground or our lab ground (copper bar) is effective, because the time we moved in this building everything was set up as is, we don’t know how is the exact electrical grounding system work or if it is working properly, difficult to test or verify.I’d like to keep some questions for next reply to this topic. Thanks

author: MisterDiodes
author_rank: Frequent Contributor
timestamp: January 21, 2018, 06:47:15 pm
content: Yes, using two ground points like that is just asking for trouble. You also need to watch out for current flows across two connected (but different) ground systems - especially corrosion effects you weren't planning on.Another way that works well: the cal lab room is supplied with a full isolation transformer and it's own safety circuit breaker distribution box coming off the transformer secondary: In that situation (a.k.a. an Island AC System) it was able to have it's very own ground rod array right smack dab in the middle of the lab room floor. Because it was an AC power system completely galvanically isolated from the utility grid, it was able to have a completely -local and isolated- grounding system - and it was setup to run on its own battery / inverter supply also. 24VAC and 48VDC supplied to test benches directly which is nice for lab use, and to keep things extra extra quiet the overhead lighting switches to 12 and 24VDC halogen incandescent. Nice. You could run LED lighting also as long as no switching power supply used, but halogens provide the best CRI.The "gotcha!" to watch out for of course is to not have anything like shielded comm's cable shields (with cable shield connected at both ends) running from that isolated room to any other room in the building... In general you don't want an accidental connection across grounding systems.Whatever you do - make sure the grounding system is completely safe, quiet, and all the breakers / GFCI work as intended.

author: dl1640
author_rank: Regular Contributor
timestamp: January 22, 2018, 11:57:54 pm
content: --Another way that works well: the cal lab room is supplied with a full isolation transformer and it's own safety circuit breaker distribution box coming off the transformer secondary: In that situation (a.k.a. an Island AC System) it was able to have it's very own ground rod array right smack dab in the middle of the lab room floor. Because it was an AC power system completely galvanically isolated from the utility grid, it was able to have a completely -local and isolated- grounding system - and it was setup to run on its own battery / inverter supply also. 24VAC and 48VDC supplied to test benches directly which is nice for lab use, and to keep things extra extra quiet the overhead lighting switches to 12 and 24VDC halogen incandescent. Nice. You could run LED lighting also as long as no switching power supply used, but halogens provide the best CRI.--Hi Mr DiodesIt looks "island ac system" is the best while it is not so easy for us to achieve.I looked into some national codes, the ac system from utility co. is TN-S, TN-C, TN-S-C, TT...each one has different grounding point..so I'd think better to connect breaker panel ground and utility ground to lab ground then to the EARTH, if lab ground is really the EARTH..

author: beanflying
author_rank: Super Contributor
timestamp: February 08, 2018, 06:33:19 am
content: Before I strip these someone suggested they may be silver plated not nickel? Anyone seen these or know of them or know a good way to tell silver from nickel?I suspect based on the cloth wiring and string looming 50's vintage is likely.

author: kj7e
author_rank: Frequent Contributor
timestamp: February 08, 2018, 02:36:07 pm
content: Use some silver polish on one of them and see if it shines up nicely. You will also have a black residue on the cloth you use. The effect will be very pronounced if they are silver and not nickel. Just from the photo, they have that silver plated look to them.

author: beanflying
author_rank: Super Contributor
timestamp: February 10, 2018, 06:34:15 am
content: And the consensus of two silver jewelers including a chemical test was Silver platedSo 22 silver plated Copper terminals at $15 AUD total spend is not a bad purchase

author: JDubU
author_rank: Frequent Contributor
timestamp: February 25, 2018, 10:34:11 pm
content: FYI:You can very quickly remove silver tarnish with a simple chemical reaction that works amazingly well and does not remove any silver. It converts the tarnish back to elemental silver.http://blog.teachersource.com/2014/01/18/chemistry-of-tarnished-silver/http://www.compoundchem.com/2013/12/16/removing-tarnish-silver/Do it outside though. It can produce a small amount of hydrogen sulfide gas (toxic).

author: cellularmitosis
author_rank: Unknown
timestamp: April 27, 2018, 04:36:24 am
content: I took a chance on taobao looking for some kelvin clips.I ordered these:https://item.taobao.com/item.htm?id=563805376375But after filing them down, they appear to be some sort of steel.However I also ordered these:https://item.taobao.com/item.htm?id=540555760189And after filing an edge down they appear to actually be copper underneath whatever the plating is.

author: quarks
author_rank: Frequent Contributor
timestamp: April 27, 2018, 08:15:04 am
content: Quote from: cellularmitosis on April 27, 2018, 04:36:24 amhave you checked with a magnet if they are steel?I am asking because I have similar Kelvin Clips and they seem to be of good quality.Attached is a pic. of another alternative which I find goodhttps://www.banggood.com/de/2Pcs-Copper-Gwinstek-LCR-Kelvin-Test-Clip-Bridge-Test-Clip-Microresistivity-Clip-p-1043337.html?cur_warehouse=CN

author: Echo88
author_rank: Frequent Contributor
timestamp: June 22, 2018, 10:34:51 pm
content: I may have overlooked the fitting post in this thread, but can someone please point me to a shop (couldnt find them on taobao) where i can find those copper spade lugs for little money?

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: June 23, 2018, 12:43:09 pm
content: The last link that I had seen was for thermocouple spades. A quick search found some that were not wide enough for binding posts...I did find these but they are not cheaphttp://www.edl-inc.com/Copper-Gold-Plated-Instrument-Lugs-25-Qty_p_51.html

author: dr.diesel
author_rank: Super Contributor
timestamp: June 23, 2018, 04:21:39 pm
content: Quote from: ManateeMafia on June 23, 2018, 12:43:09 pmDang, they also want $25 to ship a pack of lugs.We could probably get a batch cut for the community here cheaper.

author: JohnG
author_rank: Frequent Contributor
timestamp: June 23, 2018, 10:58:27 pm
content: Maybe these will work:http://www.surplussales.com/Connectors/banana.htmlLook on the page for "Gold Binding Post"Don't know anything about them, haven't cut one open, but worth a look.John

author: Kosmic
author_rank: Super Contributor
timestamp: June 24, 2018, 12:41:41 am
content: Look like ground/guard binding post (no insulation).There is tons of cool stuff on that store thought. Thanks for sharing!

author: Vgkid
author_rank: Super Contributor
timestamp: June 24, 2018, 01:16:36 am
content: Those are ESI non insulated binding posts. Often used for grounds on the ESI gear.

author: EmmanuelFaure
author_rank: Regular Contributor
timestamp: June 24, 2018, 11:06:05 am
content: Quote from: JohnG on June 23, 2018, 10:58:27 pm"Originally made in 1943, then re-packed in 1963"OMG! They're beautiful.

author: Magnificent Bastard
author_rank: Regular Contributor
timestamp: June 25, 2018, 06:14:44 pm
content: Quote from: JohnG on June 23, 2018, 10:58:27 pmGREAT find! Thanks for that!

author: Echo88
author_rank: Frequent Contributor
timestamp: June 28, 2018, 09:26:41 am
content: Regarding the Amphenol plugs "ait6e16-11pc-b30" which fit nanovoltmeters like the Keithley 181 or 148 and which are mentioned by CalMachine on page 8:I ordered two of them from Arrow Electronics, filed a bit on one of the connector-pins and found out they are made of brass instead of copper. Also: the product specification code doesnt include the statement that the pins are explicitly made of copper. Its just mentioned in the datasheet for the AIS-series: "made of brass or copper alloy".I will build one shorting plug and one measurement cable from the plugs and test them against my old measurement cable which i did buy with my K181 regarding thermal emf.

author: CalMachine
author_rank: Frequent Contributor
timestamp: June 28, 2018, 12:30:45 pm
content: Quote from: Echo88 on June 28, 2018, 09:26:41 amYou should contact Amphenol about that. After many phone conversations with them, explicitly stating I needed copper pins, that is the part number they gave me. Perhaps their own sales people weren't aware of the "Brass or Copper alloy" statement within the datasheet.I'm a little upset to learn the pins are actually brass. I hadn't ordered enough quantity to do any material testing on, so I took their word for it.

author: martinr33
author_rank: Frequent Contributor
timestamp: June 29, 2018, 02:27:46 am
content: The datasheet on Mouser for that connector states "copper alloy". No mention of brass. They are silver plated.I did grind a little off of a Mouser part. The color matches the reddish color of a copper clip that I have, and is not the bright yellow of brass.There again, the pins sit deep inside the connector and are well-shielded from air. The K182 gets quite warm, especially at the connector.

author: Echo88
author_rank: Frequent Contributor
timestamp: July 02, 2018, 07:35:45 pm
content: @ martinr33: Could you please provide the datasheet you mentioned? I couldnt find it on mouser, only on Peigenesis:http://www.peigenesis.com/images/content/pei_tabs/amphenol/ait-ms-series/new-thumbs/025-048_ait-ms_series.pdfwhich claims "Copper Alloy or Brass" as far as i could see. My measurements of the freshly made cables made from the connectors with brass were conducted at varying room temperature and therefore leave a lot to be desired:In the attachment: mV means nV, measured at the Analog Output from the K181I build a thermal short from one connector (with a copper conductor from the same cable i use for the next measurement cable) and crimped one connector to a screened copper cable of 3m, which ends i stripped and twisted and then crimped them together. I let my K181 settle with the newly built thermal short and at about 13h i changed it to the newly built measurement cable with the crimped ends. One can see the <30nVpp noise with the thermal short plug, like advertised in the K181-datasheet. After the 13h-mark the temperature varies, since im about 1m away from the K181, playing at the PC.I might buy a A23-amplifier from EM-Electronics and put it in an oven and enjoy the 1.5nVpp noise, without bothering for expensive plugs, since one can always just solder another twisted-pair-cable to the A23.

author: JohnG
author_rank: Frequent Contributor
timestamp: July 05, 2018, 06:43:08 pm
content: Just as a reminder, brass is a copper alloy. If I saw the phrase "copper alloy", I would not rule brass out unless the alloy was further specified. Just my $0.02.John

author: martinr33
author_rank: Frequent Contributor
timestamp: July 10, 2018, 01:05:31 am
content: Connector datasheet. As noted, I ground some of the plating off and saw the reddich color of copper, not the yellow of brass.https://www.mouser.com/datasheet/2/18/12-020-462735.pdfIn working with these connectors and the K182, the connectors don't seem to be an issue.I've seen some odd thermal effects (maybe 100nV rise from warming one leg of my differential cable). Odd, becasue I cannot explain them. They should balance, but they don't.

author: Echo88
author_rank: Frequent Contributor
timestamp: July 10, 2018, 08:38:46 am
content: I cant find the "AIT"-connector in your pdf. But it seems copper-contacts are always silver plated and brass ones gold plated.Anyway, my tests with my selfbuild-cables are good so far, but are limited by the K181 itself regarding resolution and noise/short term stability.I hope i find a case were i really need a good nanovoltmeter to finally buy a A23-module.

author: JohnG
author_rank: Frequent Contributor
timestamp: July 10, 2018, 02:31:49 pm
content: A few more things:The vast majority of gold plating on copper uses a nickel barrier layer plated on the copper first, and this is then plated with gold. The nickel layer is used to prevent copper diffusion into the gold, which can lead to tarnish on the surface.I think this is less of an issue with silver, but then again silver can tarnish on its own.If you have a powerful rare earth magnet, you can often tell if there is a nickel barrier coating by suspending the plated object from a thread and placing the magnet near it. You can see a slight deflection due to the nickel layer. If the plated object can be spun easily on a flat (nonmagnetic) surface, you can also use a rare earth magnet to deflect it slightly.One other word of warning. Brass is supposed to be a copper-zinc alloy, but it is often contaminated with other metals, including iron. Sometimes there is enough contamination that you can pick up the "brass" with a powerful magnet.John

author: dl1640
author_rank: Regular Contributor
timestamp: July 12, 2018, 11:05:34 am
content: I got a small loop of single-strand 24AWG pure copper wire with PTFE insulation. The seller left a tag on the wire indicating the *signal direction*. When measuring low level voltage, shall I wire the cable with regard to the signal direction sign?通过我的 PRA-AL00 上的 Tapatalk发言

author: TiN
author_rank: Super Contributor
timestamp: July 12, 2018, 02:22:13 pm
content: QuoteSounds like audiofoolery to me

author: dl1640
author_rank: Regular Contributor
timestamp: July 12, 2018, 03:26:07 pm
content: I guess so...Couldnt expect the difference between *directions*.通过我的 PRA-AL00 上的 Tapatalk发言

author: TiN
author_rank: Super Contributor
timestamp: July 12, 2018, 06:06:41 pm
content: Nanovolt DIY cables anyone?Finally got nanovolt-grade connectors.There are lots of parts per each.Conductors are non-plated UNC C18700 copper, insulator is PEEK.Aren't they pretty?LEMO P/N are EVP.1S.304.CLY for panel receptacle and FVN.1S.304.CLYC52Z for plug.

author: dl1640
author_rank: Regular Contributor
timestamp: July 13, 2018, 12:28:00 am
content: These copper are leaded so are easy for soldering, look nice.通过我的 PRA-AL00 上的 Tapatalk发言

author: HighVoltage
author_rank: Super Contributor
timestamp: July 13, 2018, 08:52:56 am
content: Original LEMO connectors are always so beautiful.TiNCan you share your source?

author: TiN
author_rank: Super Contributor
timestamp: July 13, 2018, 11:10:42 am
content: Sure, it's LEMO.I plan to build few cables for sale to fellow nutsI think i'd need just 4-5 connectors for my uses.

author: babysitter
author_rank: Frequent Contributor
timestamp: July 13, 2018, 09:15:28 pm
content: Quote from: TiN on July 12, 2018, 02:22:13 pmOf course there is no integrated electron sorting device inside the cable, but you might in some cases *want* a direction marking on a cable. If its part of a big fat nest of the electronics bird where you want to pluck out the right end of the right cable. A coworker pointed me in noting down the position of cable markings, like assemby 1 is in the direction of the first character of cable marking, assy 2 in the direction of the last character.

author: retroware
author_rank: Contributor
timestamp: August 05, 2018, 02:34:42 pm
content: I was wondering what followers of this thread think of the results presented in this paper:https://doc.xdevs.com/doc/Fluke/appnotes/nf_ncsl02.pdfThe authors were trying to verify the linearity of the Fluke 720 KVD and as such were quite concerned about EMFs due to cabling. They tried all sorts of combinations and basically concluded that tinned stranded wire was about as good as it gets. With respect to lugs, again it didn't seem to really matter whether they were tin or gold, or even whether they were used at all.

author: dl1640
author_rank: Regular Contributor
timestamp: August 06, 2018, 10:24:00 am
content: Quote from: retroware on August 05, 2018, 02:34:42 pmSo the control of the temperature and wind play the most part, regardless whatever fancy cable in use.My lab seems not controlling temperature well, to resolve 0.1ppm is not easy.

author: VK5RC
author_rank: Unknown
timestamp: August 06, 2018, 12:04:00 pm
content: Quote from: retroware on August 05, 2018, 02:34:42 pmThanks for the interesting read.I can't help but think - this paper is coming out of Fluke's Voltage Metrology Laboratory, some of their worst cables are certainly better than my my best! I suspect a whole lot of other issues that plaque the lower level volt-nut 'trainees' (like me) like earth loops, mains/computer interference/ pick-up etc etc they have solved years ago.Robert

author: ap
author_rank: Frequent Contributor
timestamp: August 06, 2018, 01:53:18 pm
content: Own measurements have shown that the plating (tin versus gold) does not make a measureable difference (at the levels discussed here), always provided copper is used as the base material. Gold has additional advantages of course.Brass e.g. used for the spade material is making a difference though, you do see differences.

author: BradC
author_rank: Super Contributor
timestamp: October 19, 2018, 04:05:57 pm
content: Quote from: JohnG on June 23, 2018, 10:58:27 pmJust a late update, but they are out of these binding posts. I got some of these however :They are really nicely plated, but after attacking one with a file, they are definitely brass underneath.(edit) Just had some more land, and I cross checked the UPC code on the packet.UPC is the same as these :https://www.digikey.com/product-detail/en/pomona-electronics/3750-0/501-1331-ND/736538, and the FSCM seems to be a match too.So they must be similar to the gold plated brass Pomona.

author: balage
author_rank: Regular Contributor
timestamp: September 10, 2019, 07:26:54 am
content: Sorry for the solicitation, but is here anybody want to buy those LEMOs for the nanovoltmeter?Those can join here:https://www.eevblog.com/forum/metrology/buying-low-thermal-emf-lemo-connector-for-nanovoltmeter-(344202182)/msg2670537/#msg2670537

author: mrk
author_rank: Newbie
timestamp: March 14, 2021, 08:59:37 pm
content: Has annyone though about using Type U(Copper+Copper) thermocouple connectors? Those are cheap and I would expect them to be optimized for measuring low voltages.

author: doktor pyta
author_rank: Frequent Contributor
timestamp: April 16, 2021, 10:34:17 pm
content: Just cut Pomona 1693-12-0 low EMF spade lugs.I was expecting crimped connections, but saw soldering.I've tried to compare the melting point of the solder against Pb60Sn40.I observed no difference.So rather not cadmium-based.The solder joint is surrounded by thick plastic barrel.

author: 1audio
author_rank: Frequent Contributor
timestamp: April 16, 2021, 11:08:20 pm
content: Having gone that far can you take a file to the spade and confirm its copper, if it actually is? Otherwise its a questionable value indeed.They could argue that you use them in pairs and all the metal to metal junctions will cancel.

author: doktor pyta
author_rank: Frequent Contributor
timestamp: April 17, 2021, 12:05:16 am
content: OK." alt="" class="bbc_img" />It's hard to have the colors right.I'm pretty sure it is true 3 layer structure: copper, silver, gold.

author: JohnG
author_rank: Frequent Contributor
timestamp: April 19, 2021, 01:36:50 pm
content: Usually gold is not plated directly on copper because the copper will diffuse into the gold. A barrier metal is used to prevent this, and nickel is the most common one. I think sometimes more expensive metals may also be used, like rhodium.So, the silvery layer is most likely nickel. If you want to test, hang the lug by a thin thread, and see if you can deflect it with a high energy (rare earth) magnet. If so, the plating is almost certainly nickel.Cheers,John

author: doktor pyta
author_rank: Frequent Contributor
timestamp: April 19, 2021, 02:15:36 pm
content: Good point.The spade lug is attracted by the neodymium magnet indeed.I'm also not sure about the solder used.I've made nanovoltmeter cable using Pb60SN40 solder and these two spade lugs.I cannot get the EMF voltage less than 300nV even after reaching thermal equilibrium.When I test original cable with spade lugs by Pomona o get approx 30nV.I've never found any info if there is cadmium in the Pomona product.Any suggestion how to determine it using simple methods?

author: beanflying
author_rank: Super Contributor
timestamp: April 19, 2021, 02:26:39 pm
content: You cant necessarily use magnetism to determine a material. Brass and most Copper alloys are weakly magnetic to modern Strong magnets.That said some of the ELectroplaters I had as customers way back when did electrical and gold decrotive work and it was a prep layer before gold but part of that was a cost thing as a thinner coating could be used.

author: antintedo
author_rank: Contributor
timestamp: April 19, 2021, 06:29:19 pm
content: Datasheet lists the base material as copper alloy 110, which is the ordinary type electrolytic copper.QuoteConsider ordering a spectroscopic analysis from a lab that does water quality testing, they are pretty cheap.QuoteI would look into the construction of the leads first. Copper wire strands should lay flat to maximize overlap and thermal conduction, solder layer should be as thin as possible.If you are willing to try exotic solders, pure indium is the most accessible thing and has about 5x lower TEMF than regular solder. SMDIN100 from Chipquik.I had good results with Sn81Bi19 (or rather Sn79Bi21 at room temp), but it has to be alloyed from base metals as nobody sells it.

author: jonpaul
author_rank: Super Contributor
timestamp: April 19, 2021, 07:54:33 pm
content: We bought many gold plated banana jumper leds in Germany decades ago.All have residual EMF ~ 1-3 uV.May still be availableJon

author: JohnG
author_rank: Frequent Contributor
timestamp: April 20, 2021, 02:15:58 pm
content: Quote from: beanflying on April 19, 2021, 02:26:39 pmA small (about 10 mm diameter, 5 mm thick, NIB) magnet will not noticeably attract high purity piece of copper or brass. I learned about this trick from an engineer who worked on MRI development. It will easily and unmistakably attract something with a thin nickel plate, which is used in the vast majority of gold-plated copper, precisely because you can use a much thinner gold plate. Otherwise, you need a much thicker and more expensive gold plating that very few are willing to pay for, unless they absolutely feel they need it.Note that I specifically said attract here, not move. If something is magnetic, or paramagnetic, the force is attractive.Brass is another story. Lots of brass has some iron content, especially cheap brass, because they melt a lot of scrap, and they are not going to spend a lot of money extracting every steel nail, screw, or hinge pin from the pile of scrap. This was a sad discovery by my MRI colleague, who discovered that hundreds of brass machine screws used in an MRI were magnetic. He learned to test them by laying them on a flat surface and seeing if a magnet would make them roll across the surface. The ones that did were not used.It is true that copper has a non-zero magnetic moment. A much stronger effect is the eddy currents induced by relative motion of the copper and magnet, but this can be alleviated by moving the magnet or copper piece very slowly.Cheers,JohnEdit: fixed a typo

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: June 01, 2021, 01:10:17 pm
content: Quote from: BradC on October 19, 2018, 04:05:57 pmFYI, the seller responded to my recent inquiry. They are not sold out."I have about 800 remaining in stock. These are 75+ years old. I do not have a factory spec but would guess that the base is brass because that was the case 99% of the time back then. It was harder than copper of the day and the threads held up better. Typically the gold plate thickness is 50-75 micro inches, 20-40 times thicker than what is typically used in current electronics. These were government specified and used parts. I have no additional information."

author: aronake
author_rank: Frequent Contributor
timestamp: November 25, 2021, 03:51:43 pm
content: Hi,Could anyone drop some names of cables that are good to use to build low thermal measurement cables?What is recommended AWG or square mm?I am thinking of building both 4 leads and 2 leads versions.Seems the general guideline is shielded PTFE cables.Links to where to buy would also be helpful.

author: ermionesrl
author_rank: Contributor
timestamp: January 28, 2022, 06:24:48 pm
content: Hello.I am about to repeat the measurement of thermal EMF of different solder alloys I did in 2016 with different equipment.Back then I used the Agilent 34401A, now I plan to use Keithley 181 and I fabricated some new all-copper cables (besides the solder joint inside the MIL-DTL-5015 connector - but I ordered a crimp one so it too will be solved), included the lugs.They are very crude, but preliminary results are very encouraging, instrument reads stable zero +- 3nV at thermal equilibrium.Here is a photo. You see the crimp and wire-wrap versions. I made also different shapes but the idea is the same... Size are 15mm x 20mm, the hole is 6mm and thickness is 1.1mm.Best regards,Andrea Baldoni.

author: julian1
author_rank: Frequent Contributor
timestamp: January 28, 2022, 10:48:09 pm
content: I just noticed the possibility of using BNC cables for shielded measurements, versus hand-rolled twisted pair. Any suggestions or preferences for bananna to BNC connectors? These are the two that I found, but I worry about the combination of alloys and thermocouple offsets.Model 1269 Pomona.pdf datasheet,https://www.pomonaelectronics.com/file/16994/download?token=cRlo0ROC(https://www.digikey.com/en/products/detail/pomona-electronics/1269/603922)MATERIALS: BNC (Female):Body: Brass, Nickel Plated, Dielectric: PTFECenter Contact: Beryllium Copper, Gold PlateBanana Plug - Body: Brass, Nickel PlatedSpring: Beryllium Copper, Nickel PlatedMueller BU-00260pdf datasheet,https://au.mouser.com/datasheet/2/279/DS-BU-00260-1622138.pdfMaterial: Body NylonBNC Plated brass body, gold-plated brass centerBanana Brass body, beryllium copper nine-leaf springs,nickel-plated

author: ermionesrl
author_rank: Contributor
timestamp: January 29, 2022, 10:13:52 am
content: Hello julian1.Electrometers have triaxial BNC connections, so the idea could work, yet current nanovoltmeters still have special low thermal EMF connectors that avoid dissimilar metals.Normal BNC, adapters and even most coaxial cables, with dissimilar plating and alloys in the inner conductor and shield, are a nightmare on this respect (triaxial BNC are gold plated in both inner conductors, at least).By the way, twisted pair work very well, why you don't want to use it? It's even cheaper to roll your own, even with teflon insulation.

author: OscarM
author_rank: Newbie
timestamp: February 10, 2022, 07:41:43 pm
content: Apologies in advance if this has been covered somewhere but I have looked and failed to find it.Is there any merit in connectors like this?Available as FMTC-CU-M for about $5It is meant for 'copper thermocouples' which strikes me as odd but might be suitable for this application.Presumably Deoxit is a good idea.Mates in chassis mounting or inline are available.PCB mounting is also available.I have also seen a version with round pins which is larger.Clearly it isn't shielded/guarded but on the other hand it is small so the coupling loop for EMI is small and the pins are in close proximity and so will be close in temperature (which shouldn't matter because it is all copper)

author: martinr33
author_rank: Frequent Contributor
timestamp: February 11, 2022, 03:02:19 am
content: I could see that working. It ise really hard to get good copper bananas!It would make a good connector for some kind of custom box - resistor testing, for example.However, most of our instruments use bananas so it isn't useful for the instrument end.

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: February 11, 2022, 03:49:09 am
content: Quote from: OscarM on February 10, 2022, 07:41:43 pmI work with K-type and S/R-type thermocouples for high-temperature applications because they are standardized. These 'copper' types are unfamiliar to me.I think there is some potential with using FMTC-CU-M as jacks. However, I would be careful about what 'pure' copper means. All metals are alloys and thermocouples work on the uniqueness of coupled alloys to make a thermal sensor.Looking at the available thermocouples that LABFACILITY manufactures, there are no Cu/Cu types -- only Cu/Cu-alloys:https://www.farnell.com/datasheets/2371070.pdfThis may suggest that the connectors you propose are actually pure copper (i.e., C101 or C110) and are used generically for all Cu/Cu-alloy thermocouples available (e.g., Cu/Cu-Ni and others). This is possible because typical thermocouples do not have a high tolerance (unless well characterized and used under the specified temperature range to prevent oxidation). For example, I usually assume a > ± 5 °C on K-types below 800 °C. When using these extension/generic connectors for general measurements, it is good enough.Furthermore, I would be concerned also with the connection quality too. They might not be as reliable as one would need for metrology-grade measurements. That being said, I have never had a problem with MINI jacks when using them for temperature measurements. Buy the high-quality brand-name ones though.More information at:https://www.thermocoupleinfo.com/Conclusion: Give it a try, but make certain that the material is actually pure copper.P.S. How are you going to clean the female connector with corrosive deoxit and expect the connection to remain consistent?

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: February 11, 2022, 04:05:30 am
content: Quote from: OscarM on February 10, 2022, 07:41:43 pmThose are standard-size thermocouples:https://www.omega.ca/en/temperature-measurement/temperature-connectors-panels-and-block-assemblies/temperature-connectors/ostw-cc/p/OSTW-CC-C-FThe TC jacks you were suggesting as a substitute for banana jacks are called MINI.

author: mendip_discovery
author_rank: Super Contributor
timestamp: February 11, 2022, 01:51:40 pm
content: I use them in the Calibration world as they are universal connector. Often used on the end of a simulator to plug into a display.You can get then in male/female options etc. Even in slightly larger sizes.

author: OscarM
author_rank: Newbie
timestamp: February 11, 2022, 06:25:16 pm
content: Quote from: leighcorrigall on February 11, 2022, 03:49:09 amI was going by pp.128 of the Keysight 34420a manual.Here, Keysight suggests putting a drop of Deoxit in the contacts of the Lemo connector.Those contacts are copper.They don't say remove it afterwards. In fact they end with 'Engage and disengage several times to distribute...'They also don't specify which Deoxit product to use which is a whopping drawback.Perhaps they mean the 'shield' version?If you don't like Deoxit (whichever one it turns out to be) there is always Santovac 5. Very viscous and about as inert as anything.Sadly I cleaned my diffusion pump and haven't filled it again.Santovac 5 won't remove oxidation but it will probably prevent it if applied to new parts which is really what we are talking about here.To test, I can either restore my HP 419A or use my HP 3456A. Neither may be ideal but they are on hand.Tentative test plan:1) Measure resistance of a loop using some of said parts once lubricated. Perhaps 5 mated pairs.2) Measure Seebeck of said loop after, I don't know, heating up one side of the connector with a hot air pencil or heating up one connector with a hot air gun and then immediately mating them.3) Put parts on shelf4) Repeat after a month.Constructive criticism of test plan welcomed.

author: 1audio
author_rank: Frequent Contributor
timestamp: February 11, 2022, 07:35:26 pm
content: it should be pretty obvious if there is a contact issue. Copper to copper Seebeck is nanovolts, Copper to copper oxide is millivolts. The only issue with the test is making sure only one contact pair is heated. if both are you may have cancellation. I hope it works out.Looking into Deoxithttps://www.hagensieker.com/wordpress/2018/06/18/deoxit-what-is-it-what-isnt-it/it seems that there are little or no corrosives in it. Its seems more to preventing corrosion. For copper that is badly oxidized I used some Brasso and then cleaned everything with isopropyl. It seems to work quite well. I would not do this unless the connector is really brown or green and otherwise a lost cause. It worked well with my vintage Keithley 148.

author: martinr33
author_rank: Frequent Contributor
timestamp: February 12, 2022, 01:24:24 am
content: I have some bare copper banana sockets on a 0Ohm resistance standard.I liberally dosed them up with Deoxit Red, screwed them loosely together and put the vinyl caps back on.Some months later, there was a tinge of green in the Deoxit and the terminals looked fine. However, that's after a very long time and with a liquid layer. Seems that Deoxit is partly oleic acid. But I would exect that acid to very quickly denature when used as instructed.The flip side is that Deoxit is pretty hopeless at treating corroded copper spades. For that, I use vinegar immersion and a fresh water rinse.I was skeptical of Deoxit for a long time. However, I have found it very effective in improving contact performance in batteries and potentiometers. And HP recommends it for use with the 3458A.Overall, you should have a small bottle around.

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: February 12, 2022, 02:28:23 am
content: Quote from: martinr33 on February 12, 2022, 01:24:24 amAcetic acid (essentially synthesized vinegar) is very effective at removing copper oxides. This is what is commonly used in metallurgy. Wear gloves and use afume hoodwell-ventilated area when using the high-molar concentrate because it will burn you and is bad for the lungs. Acetic acid stinks. To prevent tarnishing, rinse with water immediately followed by drying with a clean cloth (or compressed air when the geometry is complex). C101 will remain oxide-free for months after treatment. If the part oxidizes in a few days or weeks, you may have either contaminated it or you are working with a lower purity copper (e.g., C110 and C122).If all you can access is grocery store vinegar, heat the acid to improve its activity. An ultrasonic cleaner will also help encourage oxide stripping.

author: martinr33
author_rank: Frequent Contributor
timestamp: February 20, 2022, 10:34:45 pm
content: Here's a picture of the business end of the latest Fluke metrology cables for the 8558 multimeter.- the cable is 22GA PTFE shielded twisted pair. It is black, not white.- the ends are sleeved in silicone rubber. They are very flexible, so much so that the PTFE insulation may have been stripped back inside the sleeving. They do not behave as if they are still insulated with PTFE, as they will not hold a bend. I wonder if the insulation might have been removed and the wire untwisted to make it more flexible.

author: TimFox
author_rank: Super Contributor
timestamp: February 20, 2022, 11:08:37 pm
content: Quote from: OscarM on February 10, 2022, 07:41:43 pmThose thermocouple-style connections are designed to connect copper wires used after a ice-point calibrator (real ice or electronic circuit) that connects the thermocouple materials into the world of copper connections. Mechanically, they are the same as the connectors for J, K, etc. thermocouples that use the same alloys as the wires.

author: martinr33
author_rank: Frequent Contributor
timestamp: November 12, 2022, 05:34:16 am
content: An update on Pomona low thermal spade connectors.I started testing with magnets, and found mixed results on individual cables. eg black spades magnetic, red not.The difference is visible. Low thermal gold plating has a sort of matte look, while gold over nickel is mirror bright.What I cannot easily tell is if the nickel is a mistake, or the whole spade is a mistake (i.e. nickel over copper probably OK, nickel over brass is bad).

author: mzzj
author_rank: Super Contributor
timestamp: November 12, 2022, 09:11:16 am
content: Quote from: ap on August 06, 2018, 01:53:18 pmThis is my limited experience also. Bog standard tinned spade connectors seem to work very well on 8508A and 3458A compared to bare copper wire or the 8508A "official" zeroing fixture.All of the fancy low-emf banana connectors seem worse than 10 cent tinned spade connector. I'm thinkig this has to do with the thermal mass and conductivity: Adding a "big" hunk of copper to DVM terminals creates slightly different thermal conditions for the binding posts. This is probably even more important if your lab temperature is fluctuating.Body material, smaller mass and thermal "disturbance" seem far more important than plating.Probably a different situation with connectors that don't have as firm mechanical connection like binding post+spade as it provides sort of wiping action + ample of contact pressure.Anyone attempted to chemically strip the ordinary tinned spade connectors to bare copper? Electrolytic stripping with NaOh (drain cleaner) and 6 volt power supply seemed reasonably straightforward.

author: DavidKo
author_rank: Frequent Contributor
timestamp: November 14, 2022, 01:55:37 pm
content: Quote from: mzzj on November 12, 2022, 09:11:16 amI used HCl - it took a while, but the work was done after few weeks outdoors in the jar. The surface was than matt, so I polished it.

author: krasimir.k
author_rank: Contributor
timestamp: March 03, 2024, 10:49:51 am
content: Quote from: OscarM on February 11, 2022, 06:25:16 pmTaken from Agilient 34420A user guide page 273:"You can obtain additional DeoxIT, part number D100L2"Kind Regards,Krasimir

author: tatel
author_rank: Frequent Contributor
timestamp: March 03, 2024, 04:47:08 pm
content: Since I'm in Europe, this is what I gothttps://www.conrad.com/en/p/cramolin-schutz-1151611-lubricant-400-ml-820553.html400 ml, 10.99€This schutz thing remains over the copper as a thin film, while cramolin contaclean mostly evaporates and cramolin wasche really evaporates after cleaning the contaclean thing.Not affiliated in any way with cramolin nor conrad. But as I understand it, these products look really like the original DeOxit products, even in color. AFAIK original DeOxit was cramolin. And, 11€/400 ml looks way cheaper that what I found when I was looking for DeOxit

author: alm
author_rank: Super Contributor
timestamp: March 07, 2024, 08:11:08 pm
content: I'm not that familiar with the Cramolin product line, though I have used their Contaclean. From what I understand, Cramolin Contaclean is like Deoxit D5 (with solvent / flushing action), so I guess Cramolin Schutz (also given the name) is more like Deoxit Shield, which is advised to be used after cleaning to protect contacts against future corrosion, and leaves more of a residue. I'm not sure if this extra residue is beneficial in this application. Given Keysight's recommendation of Deoxit D100, I'd think that Cramolin Contaclean would be the better match with a better cleaning action and less (but still some) residue.

author: tatel
author_rank: Frequent Contributor
timestamp: March 09, 2024, 10:31:41 pm
content: You're probably right. Here you can see how the film looks over copper clad boards after a week in hot and humid summer with open windows. No the best pictures I took in my life but I think the difference in film thickness is clear.https://www.eevblog.com/forum/repair/no-deoxit-but-cramolin-contaclean-cramolin-protection-and-cramolin-spraywash/msg4960474/#msg4960474IIRC, original Deoxit was Cramolin, reselled or even produced under license in the US. Then there was some drama and looks as if Craig developed copies/new products.Some more testing would be in order, I guess.

author: TERRA Operative
author_rank: Super Contributor
timestamp: February 11, 2025, 11:01:23 am
content: Apologies for the gravedigging...I read most of the thread, but maybe I missed it... If I were to use shielded PTFE insulated silver plated copper wire (The stuff you see all over ebay and Aliexpress etc) crimped into bare copper lugs, would that be any worse than bare copper wire of the same construction for use with my 3458A?Also, should I do away with the copper lugs or assuming I keep them clean will they have any effect? (Although the lugs do help preserve the cable better).And finally, gold plated directly onto copper lugs (no nickel layer) crimped to silver plated wire? How would that go?

author: ch_scr
author_rank: Frequent Contributor
timestamp: February 11, 2025, 12:52:30 pm
content: Here is a snippet from theKeithley Low Level HandbookSection 3.2.2Think there also was a more detailed PDF posted about this here, but can't seem to find it.

author: Overspeed
author_rank: Frequent Contributor
timestamp: February 11, 2025, 01:36:43 pm
content: Quote from: martinr33 on February 12, 2022, 01:24:24 amHellowater to remove acid is OK , but just after than that mandatory to dry out the surface by using acetone or chloroform as that a very fast evaporating solvent and by evaporation you remove all traces of waters .If you let any trace of water / humidity you will generate oxidation .RegardsOS

author: donlisms
author_rank: Frequent Contributor
timestamp: February 12, 2025, 07:25:35 am
content: The Seebeck effect is often described as the result of letting two different metals contact each other, with something about a temperature difference possibly described in some vague way.What's really going on is that there will be current flow in a single conductor that is at different temperatures at its ends. If you tie two conductors together, you see the difference (or sum, depending on how you like to think of it) of their Seebeck EMF's at the open ends.Plating is most likely going to be so thin that the temperature difference between one "end" of the plate and the other (i.e., between the inner and outer surfaces) is inconsequential. This would especially be true with silver-plated copper, because silver and copper have very nearly the same coefficients. Very (very) small Seebeck coefficient difference multiplied by a very (very) small temperature difference.