Question: 11059A Kelvin Probe Set - Page 1
Forum section: electronics / testgear

author: smgvbest
author_rank: Unknown
timestamp: December 15, 2015, 12:09:23 am
content: I was looking at Kelvin probes and see these cost $189 new.I was wondering what it is about them the has a cost like this?is it the kelvin clips they use?is it the cables or banana plug?Just curious where the cost isOf course it could be just profitagain just curious

author: tautech
author_rank: Super Contributor
timestamp: December 15, 2015, 12:24:16 am
content: Quote from: smgvbest on December 15, 2015, 12:09:23 amYou might be interested in these:https://www.eevblog.com/forum/buysellwanted/franky's-sales-thread/msg812081/#msg812081EditAnd here's the thread:https://www.eevblog.com/forum/testgear/franky's-kelvin-clip-kit/

author: smgvbest
author_rank: Unknown
timestamp: December 15, 2015, 01:02:27 am
content: Thank you for the link and I should fix part of my post, the kelvin probes I was lookng at are Keysight/Agilent ones for 183

author: PedroDaGr8
author_rank: Super Contributor
timestamp: December 15, 2015, 01:58:33 am
content: Quote from: smgvbest on December 15, 2015, 01:02:27 amThe biggest reasons are low sales numbers, high part count, high quality and of course the corporate name. I will compare these throughout to standard test leads to explain the costs to SOME degree.When you compare the sales of Kelvin leads to test leads, the ratio is likely 1:1000. This means you have a MUCH smaller pool to make up your tooling and manufacturing costs. Additionally, when you compare these to a standard set of test leads, these are drastically more complex devices. A standard set of test leads is comprised of a sharp metal tip, soldered to a wire and then placed in a mold. Thermoset polymer is injected into the mold and then a formed set of test leads is born. This is a VERY simple, easy and CHEAP methodology. When combined with the economy of scale, this is why you can get quality test leads for very cheap. Klevin clips on the other hand have loads of parts, the wire loom, the heatshrink, 2x more cables minimum, etc. All of these parts cost money, not just to make but to assemble and these costs have to be spread over a much smaller number. Plus being a Keysight product they are likely made of at least acceptable quality parts. These are NOT budget basement parts. The people that need Kelvin clips in a corporate environment will have a much easier time getting Keysight branded ones than no name branded parts for a variety of reasons. So the fact they are from Keysight and not from Uni-T, GW Instek or PedroDaGr8's Backyard Basement Shop O' Fun is worth some money.Now does all of this add up to $189, not really but that is what they thing the market will bear. Plus, the high price gives them some leverage in negotiations on instruments. They can throw in this "$189" set of leads for free! In reality it maybe cost them $20-30 in parts and assembly MAXIMUM. Frankly, in Kelvin clips you don't really need that high of quality. As several people mentioned, you can make the wire as thin as possible to carry the current without affecting your reads.

author: smgvbest
author_rank: Unknown
timestamp: December 15, 2015, 02:37:44 am
content: So there is not a special cable type just standard silicone test lead cable, high quality banana lug and the kelvin clips and that's all

author: BravoV
author_rank: Super Contributor
timestamp: December 15, 2015, 03:21:02 am
content: Quote from: smgvbest on December 15, 2015, 02:37:44 amNot an expert though, suggesting to download this excellent book ->Agilent Impedance Measurement Handbook (PDF)The clips actually nothing special, of course as long the 4 contact points can maintain good contact and with consistent results, not easily get rusted, mechanically good and etc.The wires, as PedroDaGr8 pointed above, nothing special on the 4 conductors, but .. at special case where you want to measure impedance especially at high frequency (typically > 100KHz) using a high end LCR meter, the dielectric of the cable's insulator becomes a factor. Teflon (PTFE) coax cable usually comes into play.But for just ordinary resistance measurement, I believe the wire insulator type doesn't matter.Again, suggesting to read above book.

author: MarkL
author_rank: Unknown
timestamp: December 15, 2015, 03:29:36 pm
content: Quote from: smgvbest on December 15, 2015, 02:37:44 amThere's more shielding on the 11059A than your ordinary kelvin clips.The four connecting cables are actually RG174/U MIL (nice and flexible) from the banana plugs all the way to the clips.The fifth banana plug connects to all the shields on the meter end, which you would plug into the guard jack. The guard wire is carried through the loom on a fifth wire and terminates on an alligator clip to attach to any shielding surrounding the DUT.Whether you need the extra shielding is up to your application, but most would probably not need it.