Fluke 5440A-7002 Low Thermal Test Leads - Page 1
Forum section: electronics / general

author: Kenny Powers
author_rank: Contributor
timestamp: February 12, 2017, 07:46:21 pm
content: Hi All,I am looking to make up a set of leads like these one Fluke supply using Belden 8262cable.http://us.flukecal.com/products/accessories/test-leads-probes-and-clips/5440a-7002Can anyone advise where I could get the adapter at the end of the lead with the 3 4mm connections? is that Guard Blue wire just connected to the black?Thanks for your help.

author: e61_phil
author_rank: Frequent Contributor
timestamp: February 12, 2017, 08:07:55 pm
content: The blue wire is connected to the screen of the two coaxial cables.

author: Kenny Powers
author_rank: Contributor
timestamp: February 12, 2017, 08:17:42 pm
content: And the black wire is also connected to the screen?

author: CalMachine
author_rank: Frequent Contributor
timestamp: February 12, 2017, 08:24:22 pm
content: You should look into Belden 8719.

author: dacman
author_rank: Frequent Contributor
timestamp: February 12, 2017, 08:26:22 pm
content: The High (red) is a shielded coax and the Low (Black) is also a shielded coax. The Blue is attached to both shields. (Two parallel RG-58/U cables, one High, one Low.)

author: Kenny Powers
author_rank: Contributor
timestamp: February 12, 2017, 08:29:28 pm
content: That makes more sense I didn't realize from the picture there were 2 coax cables.Thanks,

author: Kenny Powers
author_rank: Contributor
timestamp: February 12, 2017, 08:45:19 pm
content: Thanks guys found the rest of the answers in various other threads.

author: CalMachine
author_rank: Frequent Contributor
timestamp: February 13, 2017, 12:18:34 am
content: Quote from: Kenny Powers on February 12, 2017, 08:45:19 pmI have not. I've been comparing a lot of different cable types for AC applications in another thread. I just received my order of Belden 8719 and fashioned me up a nice cable I plan on testing some AC measurements with! I don't have a good set of Fluke leads or anything, so it's hard to get a baseline comparison.What seemed a little interesting to me is, the 5440S-7002 has tinned copper conductors... From my understanding, tinned copper will induce higher thermal EMF errors than bare Copper or Gold/Silver plated Copper.

author: Tony_G
author_rank: Super Contributor
timestamp: February 13, 2017, 05:41:43 am
content: As an aside, does anyone know where to buy these as OEM items?

author: quarks
author_rank: Frequent Contributor
timestamp: February 13, 2017, 02:01:31 pm
content: where possible, I much prefer using spade connectors instead of 4mm banana plugsif you want to make your own DIY low emf cables, have a look athttps://www.eevblog.com/forum/metrology/diy-low-emf-cable-and-connectors/msg190302/#msg190302

author: Kenny Powers
author_rank: Contributor
timestamp: February 13, 2017, 06:54:11 pm
content: I picked up a few feet of Belden 8719 instead, 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 34401As

author: Bill158
author_rank: Regular Contributor
timestamp: February 13, 2017, 09:35:09 pm
content: Quote from: Kenny Powers on February 13, 2017, 06:54:11 pmBelden 8219 has Tinned Copper Conductor and it is stranded. I have three of the Fluke Low Thermal cables 5440A-7002 from different sources. One was made with Belden 8240, and the other two were made with Intercomp P/N 2482A. All three say RG-58/U (solid bare copper conductor) on them. So to try to reproduce the Fluke original I purchased JSC Wire & Cable RG-58/U instead of the Belden, but it is equivalent to the Belden 8240. I then found some so called "Gold Plated" Banana plugs that have a screw to connect the center conductor and allow the RG-58/U center conductor to enter from the end rather than from the side as in the Pomona 5406 which is made from gold plated beryllium copper which is hopefully "low thermal". While Pomona doesn't state that the 5406 is low thermal some simple experiments seem to indicate they are. Yes, the Fluke leads are two parallel RG-58/U coax cables with the blue third lead hooked to the shield of both cables. So I made up a reasonable copy of what Fluke had done with the unknown manufacturer's banana plugs. They appeared to be gold plated so I bought them. I have no idea what the body is made from or what the spring is made from. It could be beryllium copper as they have worked well for a few years without loosing their "springiness" so to speak.See the attached pictures of what I have done. 1819 is the original Fluke cable, 1817 is my imitation of what Fluke has done (with my unknown banana plugs on the ends). 1962 has the Pomona 5406 on the left with two of my unknown manufacturer on the right, one assembled and one disassembled (1963 is a closer view). The unknown also has a hole where a banana plug can be inserted from the side for an additional cable if necessary. The screw then clamps the center conductor of the RG-58/U securely to the plug without soldering. I allow three minutes after insertion before making a measurement to allow any thermals to dissipate. I still need to find a good way to measure the thermal effects of this. One crude way is to just plug the cables in and then put my fingers on the plug/jack combination and see what effect this has at the input to my HP 3458A. I do know that the Fluke does NOT react much to this "test", at least at the sub microvolt level. Right now this seems to work ok for me.Bill