Good Priced Low Thermal Leads and Parts

Started by Hawaii596, 04-08-2014 -- 19:15:10

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Hawaii596

04-08-2014 -- 19:15:10
So I know the Fluke 5440A series is one of the best.  We recently had the Fluke traveling standard in house to do a comparison on my Fluke 732A (good news, 0.55 ppm extrapolated 1 year uncertainty - sorry, rabbit trail).

A few years ago I bought some replacement copper elements for the banana plugs on my Fluke 5440A-7002 lead sets.  I don't remember where I bought them.  Time to get some more.  So first question, does anyone know where to buy replacement copper banana elements?

Second question, are there more cost effective good low thermal cable brands out there?  I did buy a spool of shielded twisted pair with braid shield.  It looks like it is Belden 8762, which is tinned copper braid in each of the leads.  Looks like AWG20 with 7x28 being the strands (7 strands of AWG28 in each lead).

This was from a recommendation from someone who used to work at Fluke standards lab.  Maybe that person will read this.

So I am thinking of buying some good low thermal banana plugs to attach.  I know I need to stay low thermal.  So copper I think.  But the leads that came in with the Fluke traveling standard used Gold bananas.  Is Gold adequately low thermal emf?  If so, do I use normal solder? 

Bottom line is I am setting up to intercompare 10 VDC references, and calibrate up to 5720A's, Fluke 8508A's (eventually) the good cal's on HP 3458A's.  So I want to get good cabling.  This has been a long time in prep (a few years).  All standards are finally cal'd.  Getting ready for dry runs.  It will still be a while until I am ready for prep for ISO17025.  Meanwhile, any knowledgeable ideas about cables and connectors would be greatly appreciated.

COPPER SPADE LUGS.  Also, any recommendations for brand or vendor for copper spade lugs?  Same context.
"I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind."
Lord Kelvin (1824-1907)
from lecture to the Institute of Civil Engineers, 3 May 1883

quarks

#1
04-09-2014 -- 08:11:54
Hello,

for real low EMF measurements I prefer crimped spade lugs (see picture).
I contacted TE about these AMP spade lugs, but unfortunately nobody knew anything about them.
If anyone knows where to get these, please let me know.

Right now the best solution is probably to go for jswilley products (like 2758-Fork) :
http://jswilley.com/Accessories.html

But if you want banana, have a look at MC parts:
http://www.multi-contact.com/downloads/ma.php?cat=tm

About cables, I have tested quite a lot and found plain Telefon cable (twisted pair with solid copper wire) is working well (and also is very cheap), but you have to take care of oxidation and only use it at low voltages.

If you want something like Fluke 5440A-7002 or 7003, have a look at Pomona 1756 (very good, but spade lug material is so thick you cannot stack two in the same binding post). Otherwise Belden Types 8422 / 8719 / 8762 seem to be really good choices.

bye
quarks

metrologygeek

#2
04-09-2014 -- 08:58:39
I've got an old (obsolete) Keithley 1483 low thermal EMF connection kit which includes gold plated lugs of various sizes and configurations. I use the Belden 8762 20 ga wire, and it works very well. I have a number of four-conductor assemblies, also. All of the cables used in primary temperature on the physical side where I work are constructed in-house, and over on the other side of the house in primary electrical we use exactly the same configuration of cables. Luckily (for me) I have enough stock left in the Keithley kit to last a few more years 'cause Keithley discontinued it quite a while ago. I would not recommend using bananas for your high accuracy low-thermal DC measurement setup.

Hawaii596

#3
04-09-2014 -- 09:01:33
The bottom photo of a banana plug looks like it may be the exact one used by FLuke in their fixturing they sent for calibration of my Fluke 732A.  I may go ahead and buy those.  Thank you for that info.

I also have an Agilent 34420A meter with low voltage  that uses copper spade lugs.  One of them broke off and we replaced it with gold.  But the gold doesn't do quiet as good a job at very low voltages.  Maybe I'll take a look to see what brand the original spade lugs are on that cable (Keithley sells the same cable assembly on their website as well).

I have numerous sets of 5440A-7002 (banana).  A few years ago I replaced some of the banana contact springs.  I found a vendor to sell those copper replacements, but I just can't find it again.  I have a spool of cable as mentioned in my original post, which I can use along with some of these banana plugs in your photo.
"I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind."
Lord Kelvin (1824-1907)
from lecture to the Institute of Civil Engineers, 3 May 1883

Hawaii596

#4
04-09-2014 -- 09:05:27
METROLOGYGEEK- I think in Fluke's setup, the way they got around it was they did a variety of forward and reverse measurements (good practice to null lead compensation any way).  But they had a setup which looked like it used gold banana plugs like in the photo in QUARKS' post.  I think I have seen the old low thermal kits from Keithley.  I believe a lab I worked at a number of years ago had one of those kits.  If I could just ID the brand of the copper spades on the end of the HP 34420A cable assembly, I think I'd have something.
"I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind."
Lord Kelvin (1824-1907)
from lecture to the Institute of Civil Engineers, 3 May 1883

Hawaii596

#5
04-29-2014 -- 17:08:10
I just inherited some version of a Keithley 1483 kit.  I opened one of the pouches (previously sealed) and it had really nice copper spade lugs.  Very nice stuff.
"I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind."
Lord Kelvin (1824-1907)
from lecture to the Institute of Civil Engineers, 3 May 1883

measure

#6
05-05-2014 -- 13:46:20
Hawaii, Fluke sells replacement spring contacts for the 5440A-7001 and 5440A-7002 (banana) lead sets, though I don't know the part number off the top of my head. They also sell a lead set, 5440A-7003, that uses the same high-quality cable as the aforementioned but is terminated with gold-plated spade lugs instead of sheathed, banana plugs. I agree with the 'geek' that spade lugs are superior for low uncertainty connections, based on my experience. Good Luck!

KKilo

#7
08-15-2014 -- 11:40:35
Hi all,
I'm a noob here. This my first post, but been managing the cal lab here for 9yrs.
Try this: http://www.douglasconnection.com/searchquick-submit.sc?keywords=TSTW38NP
I have a set, at $13 (2013 USD) a pair not too shabby but they are not the ordinary banana-like spring.
I asked them for a certificate of origin and they ignored me...uncertain these are genuine Tellurium but for the price. They come with rubber gloves and cleaning wipes.
k

Hawaii596

#8
08-18-2014 -- 15:35:47
Thanks all for the numerous helpful inputs.  Sad that it is mostly the high end audiophile stuff.  In high quality (good, low thermal connectors), we kind of don't get much of our own.  By the way, I also recently inherited two boxes of the old Keithley copper kits.  I presume those are long discontinued; but should be brought back. Those are great kits.
"I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind."
Lord Kelvin (1824-1907)
from lecture to the Institute of Civil Engineers, 3 May 1883

jwilley127

#9
12-29-2017 -- 08:01:10
Old thread but just an FYI...

36" 20 AWG dual conductor shielded twisted pair PTFE dielectric
cable terminated with LTE low thermal EMF ¼" forks

36" 20 AWG dual conductor shielded twisted pair air/PTFE dielectric cable terminated with LTE low thermal EMF ¼" forks

Now available through JW Solutions
JW Solutions
Resistance, Temperature & Pressure Standards
Test Equipment & Accessories
Calibration & Repair Referrals
407.340.7323
jwilley127@gmail.com

microwave-kevin

#10
01-15-2018 -- 23:54:34
NMI's have also faced this problem and they have solutions, I bought my lugs, dies and tool from METAS.

They are made for metrology (METAS is the NMI of Switzerland)

I love the ease of use and it is a tool / crimp that has specs.

http://metasweb01.admin.ch/euromet/copperlugs/copper_lugs.pdf


Aloha

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