Author Topic: DIY Low EMF cable and connectors  (Read 64728 times)

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Online martinr33

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Re: DIY Low EMF cable and connectors
« Reply #175 on: September 16, 2017, 06:28:35 pm »
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..
 

Offline MisterDiodes

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Re: DIY Low EMF cable and connectors
« Reply #176 on: September 17, 2017, 12:43:35 am »


I think that my meter jacks are gold plated, so I am facing gold no matter what..

None 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.
 

Offline Neomys Sapiens

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Re: DIY Low EMF cable and connectors
« Reply #177 on: September 17, 2017, 10:44:20 pm »
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.
 

Offline cellularmitosis

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Re: DIY Low EMF cable and connectors
« Reply #178 on: September 19, 2017, 03:49:04 am »
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.
« Last Edit: September 19, 2017, 03:53:24 am by cellularmitosis »
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Offline lukier

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Re: DIY Low EMF cable and connectors
« Reply #179 on: September 25, 2017, 02:37:18 pm »
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?
 

Offline CalMachine

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Re: DIY Low EMF cable and connectors
« Reply #180 on: September 25, 2017, 04:50:34 pm »
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 well

Connector - AIT6E16-11PC-B30 (Gold Plated, Copper Alloy, Crimp connection)
Cable - Belden 5500FE (~1.5m)
Spades - Bare copper crimp spades

I 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  :-+













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Offline 0.01C

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Re: DIY Low EMF cable and connectors
« Reply #181 on: September 26, 2017, 02:49:48 am »
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?
I just send your message to the taobao seller , you can file a item not received case on taobao to get full refund.
« Last Edit: September 26, 2017, 02:52:58 am by 0.01C »
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0.01C
 

Offline 0.01C

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Re: DIY Low EMF cable and connectors
« Reply #182 on: September 26, 2017, 03:00:48 am »
Seller reply your item is on the way now , the tracking detail update very slow ,please wait some more days
Guildline Datron Fluke L&N ESI HP
0.01C
 
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Offline 0.01C

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Re: DIY Low EMF cable and connectors
« Reply #183 on: September 26, 2017, 03:07:55 am »
Seller will reply you here
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Offline Squantor

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Re: DIY Low EMF cable and connectors
« Reply #184 on: September 26, 2017, 07:44:17 am »
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 well

Connector - AIT6E16-11PC-B30 (Gold Plated, Copper Alloy, Crimp connection)
Cable - Belden 5500FE (~1.5m)
Spades - Bare copper crimp spades


Where did you get the  AIT6E16-11PC-B30 from? I have been looking for a solution for my Keithley 150B for ages.
 

Offline lukier

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Re: DIY Low EMF cable and connectors
« Reply #185 on: September 26, 2017, 07:48:36 am »
Buy the  binding posts from taobao,you can through Taobao tools "wangwang"contact the seller,see that

Seller reply your item is on the way now , the tracking detail update very slow ,please wait some more days

Thanks 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.
« Last Edit: September 26, 2017, 10:13:44 am by lukier »
 

Offline 0.01C

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Re: DIY Low EMF cable and connectors
« Reply #186 on: September 26, 2017, 07:11:10 pm »
Buy the  binding posts from taobao,you can through Taobao tools "wangwang"contact the seller,see that

Seller reply your item is on the way now , the tracking detail update very slow ,please wait some more days

Thanks 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.
your item is arrived in the UK.
Guildline Datron Fluke L&N ESI HP
0.01C
 

Offline lukier

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Re: DIY Low EMF cable and connectors
« Reply #187 on: September 26, 2017, 07:46:37 pm »
your item is arrived in the UK.

Yup, 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 :)
 

Offline CalMachine

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Re: DIY Low EMF cable and connectors
« Reply #188 on: September 26, 2017, 08:17:46 pm »
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 well

Connector - AIT6E16-11PC-B30 (Gold Plated, Copper Alloy, Crimp connection)
Cable - Belden 5500FE (~1.5m)
Spades - Bare copper crimp spades


Where did you get the  AIT6E16-11PC-B30 from? I have been looking for a solution for my Keithley 150B for ages.

It 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.
« Last Edit: October 01, 2017, 03:04:28 am by CalMachine »
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Offline branadic

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Re: DIY Low EMF cable and connectors
« Reply #189 on: September 30, 2017, 11:39:46 pm »
Sorry to hack this thread, but maybe someone in here can help. Were can I get those security gold plated copper posts used 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-
Fluke 8050A | Prema 5000 | Prema 5017 SC | Advantest R6581D | GenRad 1434-G | Datron 4000A | Tek 2465A | VNWA2.x with TCXO upgrade and access to: Keysight 3458A, Keithley 2002, Prema 5017 SC, 34401A, 34410A, Keithley 2182A, HDO6054, Keysight 53230A and other goodies at work
 

Offline lukier

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Re: DIY Low EMF cable and connectors
« Reply #190 on: October 01, 2017, 12:03:52 am »
Sorry to hack this thread, but maybe someone in here can help. Were can I get those security gold plated copper posts used 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?

Security 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/CT2912

If 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.
 

Offline The Soulman

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Re: DIY Low EMF cable and connectors
« Reply #191 on: October 01, 2017, 09:43:19 am »
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%2Bgold

I 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?
 

Offline Echo88

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Re: DIY Low EMF cable and connectors
« Reply #192 on: October 01, 2017, 10:03:33 am »
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.
 

Offline VK5RC

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Re: DIY Low EMF cable and connectors
« Reply #193 on: October 01, 2017, 10:15:33 am »
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 Mouser http://au.mouser.com/ProductDetail/Pomona-Electronics/3770-0/?qs=yih5jomMvb3Uhbdu3XO%2FAg%3D%3D
Data Sheet http://www.mouser.com/ds/2/159/d3750_60_70_1_01-34263.pdf
Whoah! Watch where that landed we might need it later.
 

Offline branadic

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Re: DIY Low EMF cable and connectors
« Reply #194 on: October 01, 2017, 11:04:38 am »
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-
Fluke 8050A | Prema 5000 | Prema 5017 SC | Advantest R6581D | GenRad 1434-G | Datron 4000A | Tek 2465A | VNWA2.x with TCXO upgrade and access to: Keysight 3458A, Keithley 2002, Prema 5017 SC, 34401A, 34410A, Keithley 2182A, HDO6054, Keysight 53230A and other goodies at work
 

Offline ManateeMafia

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Re: DIY Low EMF cable and connectors
« Reply #195 on: October 01, 2017, 12:33:22 pm »
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.
 

Offline Echo88

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Re: DIY Low EMF cable and connectors
« Reply #196 on: January 07, 2018, 04:39:12 pm »
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?  :-DD
 

Offline ManateeMafia

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Re: DIY Low EMF cable and connectors
« Reply #197 on: January 07, 2018, 05:16:51 pm »
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.
 

Offline Echo88

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Re: DIY Low EMF cable and connectors
« Reply #198 on: January 09, 2018, 02:29:18 pm »
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?
 

Offline dl1640

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Re: DIY Low EMF cable and connectors
« Reply #199 on: January 19, 2018, 03:59:45 am »
Remember 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.

i 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!
 


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