Author Topic: DIY Low EMF cable and connectors  (Read 60483 times)

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Online Echo88

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Re: DIY Low EMF cable and connectors
« Reply #225 on: July 03, 2018, 05:35:45 am »
@ 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.pdf which 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 K181
I 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.  :popcorn:
 

Online JohnG

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Re: DIY Low EMF cable and connectors
« Reply #226 on: July 06, 2018, 04:43:08 am »
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
 

Offline martinr33

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Re: DIY Low EMF cable and connectors
« Reply #227 on: July 10, 2018, 11:05:31 am »
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.pdf

In 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.
 

Online Echo88

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Re: DIY Low EMF cable and connectors
« Reply #228 on: July 10, 2018, 06:38:46 pm »
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.  ;D
 

Online JohnG

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Re: DIY Low EMF cable and connectors
« Reply #229 on: July 11, 2018, 12:31:49 am »
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

 

Offline dl1640

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Re: DIY Low EMF cable and connectors
« Reply #230 on: July 12, 2018, 09:05:34 pm »
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?

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Offline TiN

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Re: DIY Low EMF cable and connectors
« Reply #231 on: July 13, 2018, 12:22:13 am »
Quote
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?

 :popcorn: Sounds like audiofoolery to me  :-DD
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Offline dl1640

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Re: DIY Low EMF cable and connectors
« Reply #232 on: July 13, 2018, 01:26:07 am »
I guess so...
Couldnt expect the difference between *directions*.

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Offline TiN

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Re: DIY Low EMF cable and connectors
« Reply #233 on: July 13, 2018, 04:06:41 am »

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.
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Offline dl1640

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Re: DIY Low EMF cable and connectors
« Reply #234 on: July 13, 2018, 10:28:00 am »
These copper are leaded so are easy for soldering, look nice.

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Online HighVoltage

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Re: DIY Low EMF cable and connectors
« Reply #235 on: July 13, 2018, 06:52:56 pm »
Original LEMO connectors are always so beautiful.

TiN
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Offline TiN

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Re: DIY Low EMF cable and connectors
« Reply #236 on: July 13, 2018, 09:10:42 pm »
Sure, it's LEMO  ;D.

I plan to build few cables for sale to fellow nuts :) I think i'd need just 4-5 connectors for my uses.
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Offline babysitter

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Re: DIY Low EMF cable and connectors
« Reply #237 on: July 14, 2018, 07:15:28 am »
Quote
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?

 :popcorn: Sounds like audiofoolery to me  :-DD

Of 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.

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Offline retroware

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Re: DIY Low EMF cable and connectors
« Reply #238 on: August 06, 2018, 12:34:42 am »
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.pdf

The 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.

 

Offline dl1640

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Re: DIY Low EMF cable and connectors
« Reply #239 on: August 06, 2018, 08:24:00 pm »
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.pdf

The 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.

So 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.
 

Offline VK5RC

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Re: DIY Low EMF cable and connectors
« Reply #240 on: August 06, 2018, 10:04:00 pm »
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.pdf

The 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.
Thanks 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
Whoah! Watch where that landed we might need it later.
 

Offline ap

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Re: DIY Low EMF cable and connectors
« Reply #241 on: August 06, 2018, 11:53:18 pm »
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.
« Last Edit: October 20, 2018, 09:47:12 am by ap »
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Offline BradC

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Re: DIY Low EMF cable and connectors
« Reply #242 on: October 20, 2018, 03:05:57 am »
Maybe these will work: http://www.surplussales.com/Connectors/banana.html

Look on the page for "Gold Binding Post"



Don't know anything about them, haven't cut one open, but worth a look.

John

Just 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.
« Last Edit: November 02, 2018, 10:57:27 pm by BradC »
 


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