Gold plated banana plugs - question

[cdev]

I recently bought a set of Kelvin clips with a banana plug connection and also at around the same time got a package of gold plated banana plugs from ebay with the purpose of making up a bunch of nice test leads with thick low-resistance copper wire.

However, I was kind of distressed to find when they both arrived within a few days of one another that their banana plugs all had a swiveling pin in the center so the handle and its attached wire rotates.

Currently the connections they make aren't particularly noisy but I can see some (currently small) interruption in the continuity (on the oscilloscope) when voltage is applied and banana connector 'swiveled'.

Its likely a dab of solder on each end would permanently anchor the plugs so they cannot swivel without covering the curved portion of the plug where the electrical connection is made.

Would you do/have you done that? Is there any reason I shouldn't?

[MK]

check in an incononspicous part of the plating to see if they are brass anyway, if they are then they are ok for 4.5 digit meters, but it might help you decide what to do with them...

[cdev]

How could I tell?

Will Google a bit more, I should have before posting.

The main reason I would like to be able to measure very low resistances accurately is because having a very low resistance can make a huge difference with the "Q" factor with loop antennas, specifically.

They look like gold plating, although they might be brass under the gold.

The meter that I'm hoping to use the Kelvin clips on is a GWInstek GDM-8251A and it has 120000 counts.

I will take a good photo of them with a tripod and decent lighting and upload it here in a bit.

[Kleinstein]

The possibility to rotate can be a problem in some cases, as this is an extra movable contact. However for the kelvin clips this should not be a problem, as the cable resistance should not matter.

For testing how good the connectors are from the point of thermal EMF, one could do a test. In the lowest voltage range of the meter use such a cable for a short and touch one of the connectors with the hand to warm it. This should be a worse than the worst normal use case. If you see a voltage of more than about 10 digits one might have to consider better plugs or some care when using them for low DC voltages.

Just a gold coating would not be a problem, as the metal is usually so thin that there is essentially no temperature difference across the coating. If the coating is more than 1 mm I would not complain either. 

[cdev]

Okay -

It does appear to be working..

My meter is still settling down, it seems. When turned on it registered around 16 uv with the Kelvin leads shorted and now its showing around 0-1 uv

its set to the 100 uv range.


I'll wait a bit longer and see if it gets to zero. Warming one plug up doesn't seem to generate measurable voltage.. but I am not sure if I am doing it correctly.


This is actually the first time Ive attempted to measure such a low voltage. 

It shows the current coming out of an LED from ambient light shining on it.

[Vtile]

I would also use a magnet to test if they are iron ...As many Chinese banana plugs are (the ebay source).

[cdev]

Thank you for that, indeed, they do appear to be attracted to a magnet..

All of the banana plugs on test leads that I have here are!

[MK]

check it is not just the screw that is attracted to the magnet, also the way to tell what is under the gold plate is to file a lttle bit of the plating off in some non contact area somewhere that does not affect the measurements.

[cdev]

It does seem like it is the (central holding) screw mostly which is being attracted..

check it is not just the screw that is attracted to the magnet, also the way to tell what is under the gold plate is to file a lttle bit of the plating off in some non contact area somewhere that does not affect the measurements.

Need to find some photos of what typical "underlying metals" might look like at 20x magnification.

[Vtile]

Is the part arrow points in attached picture, the "central pin screw" you are referring?

[cdev]

Yes and on mine that part is not gold plated, its silver colored. the other side of the 'swivel' is though, thats the part the screw to hold the wire screws into.

[MK]

It does seem like it is the (central holding) screw mostly which is being attracted..

check it is not just the screw that is attracted to the magnet, also the way to tell what is under the gold plate is to file a lttle bit of the plating off in some non contact area somewhere that does not affect the measurements.

Need to find some photos of what typical "underlying metals" might look like at 20x magnification.

The underlying metals might be steel, brass or copper.

[Vtile]

It is typical Chinese banana plug cheapening it seems, I do have also those which have the ferromagnetic material used in the body of the connector, to overall quality on those are also poor and do have those "connection" issues. One tweak is to use a hammer to squeeze the head of the connector a bit to make better contact with the loose spring assembly and body if the structure is the same as on the connector I attached picture of (which are also chinese Uni-T branded and do not suffer noticeable issues and aren't magnetic ... at least the one pair I do have).

[cdev]

For what I paid they are still a good value, they just need a tiny bit of work to make them what I was hoping for.

I think I'm going to add the dab of solder to stop them from spinning. That should be enough for now, the screw seems to hold the wire fairly securely. If not I'll solder that too.

[sleemanj]

I've posted about this before recentlyish, recent batches of banana plugs i've had from China have had very very loose spring bits, from multiple suppliers.

i ended up soldering the springy bits top and bottom,  I hung them by the cross-hole on the soldering iron tip, heated, and flowed solder in as appropriate, you can do it pretty tidy.  It's a PITA, but without doing so in my opinion they were near worthless.

The cross holes on some were also very bad and would need drilling, they went in my junk drawer.

I have not had such bad ones before.

[sleemanj]

[cdev]

I tried to explain to the seller what I was looking for and what I might have to do. I wasnt sure if they understood me.

But I tried.

[martinr33]

I've been looking for reasonably priced copper banana plugs before.

If you file off the plating at the back of the connector and see reddish metal,let us all know!

You most likely have brass. Brass is yellow, close in color to the plating. If you are unlucky, you will have steel or even pot metal which look gray.

Generally, brass in Chinese  seems to translate to copper in English. However, as I noted, there is little chance or risk of getting copper.

All that said, you will have a hard time getting to a millivolt of error. Tens of microvolts, if there is a temperature difference between the contacts.

[Alex Nikitin]

I am using these plugs with good results.

Cheers

Alex

[cdev]

Is "multi-contact" a trade mark/brand or a generic term for that kind of plug?

I am using these plugs with good results.

Cheers

Alex

[Alex Nikitin]

Is "multi-contact" a trade mark/brand or a generic term for that kind of plug?

I am using these plugs with good results.

Cheers

Alex

http://ec.staubli.com/

Cheers

Alex

[Awesome14]

Chinese commerce standards dictate that any metal that is gold-colored can be referred to as 'gold'. Ebay is pretty good at keeping the Chinese from marketing gold-colored jewelry as 'gold', but banana plugs I'm not so sure.

[glarsson]

One can easily detect that the inner metal is an alloy - not pure tellurium copper ...

Tellurium copper, CuTe, is an alloy of mostly copper with a small part of tellurium. What other alloy are you referring to?

[cdev]

What's a good setup to take advantage of sense wires?

Right now my desk is not so roomy so my power supplies are a good two meters from my desk. Enough so there has been quite measurable voltage drop in my previous power wires.

I'm making up new cables and Ive decided to solder the banana plugs everywhere I use them. I think I am going to try crimped and then soldered spade lugs for the power leads in stead of banana plugs. Less chance of them coming off, also they are flatter, so more surface area to make contact. if the wires are stranded and clean (freshly stripped and maybe cleaned with IPA) and the wire gauge is enough to fill the interior of the crimp connector fully before crimping, should I solder it as well, or will that not add much?

On my power supply there is no choice for the sense wires, it just takes banana plugs.

I have some fairly thin shielded two conductor wire. Recently when Ive used that for power lines (but its too thin) for my electronics Ive been connecting the shield to ground. It did seem to make an improvement (reduction in RF noise) That wire is too thin for use for power cables except when the current is really low but it does seem like it might be ideal for sense wires. They are twisted on the inside but not as much as say the thin wire from Ethernet cables. Basically they are my two options for sense wires. Is using Ethernet wire not good- too thin? if it has a longish distance to go?
( as I said two meters or perhaps even more.)  I wish my power supplies were smaller. All but my little HP take up a fair amount of space.

[Andreas]

MC - Multi-Contact - Staubli:
The well-respected (german) company Staubli is the owner of the Multi-Contact brand (not to be confused with a white good MC brand from Farnell PLC) - Staubli used to be the parent company of Hirschmann - (famous for its BUELA 20K banana plug) - and Hirschmann brand was recently acquired by Belden Cable.

Hello,

I think you are mixing up some things:
Stäubli and MC are Swiss companies.
https://de.wikipedia.org/wiki/St%C3%A4ubli_International

Hirschmann is a german founded company.
Afaik there is/was no connection to MC/Stäubli.
Aquisition by Belden was in 2007.
http://www.beldensolutions.com/en/Company/About_Us/belden_brands/belden_history/index.phtml
https://de.wikipedia.org/wiki/Hirschmann_(Unternehmen)

With best regards

Andreas

[beanflying]

Interesting thread. A few of the earlier replies stated to test with a magnet. Brass and in fact some copper alloys are mildly magnetic to strong magnets. So to state they are non magnetic is not a good guide or method.

I have just tested some of my older Gold Bullet connectors from some earlier electric R/C (circa 20 years old) and they are weakly magnetic and they were at the time definitely Gold Plated 'brass' ex Germany and very expensive. We incidentally were pulling 90-100A plus at 25V+ through these at the time. The trend is toward 6mm and 200A+

The couple shown below are some cheap sub $1 each ebay ones and some very cheap ebay ones. The Red and Black ones appear to be brass back end and either the shield or pin at the front is iron based. The colourful ones exhibit the same sort of magnetic properties as my old ones in that the Neo magnet stack will attract them but is not sufficient to pick one up. https://www.ebay.com.au/itm/10set-5color-Gold-Plated-Brass-Stackable-4mm-Banana-Plug-Speaker-Cable-Connector/253102319127?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

edit: just removed the shield of the red and black and it is the spring that is iron based, the entire underlying pin and back end appear very mildly magnetic like the others.

If the plating is in fact gold on either is a completely different matter

[beanflying]

Just for a little more info I have dismantled for 4mm evilbay binding posts I had in stock. Nuts and washers on both are Iron based Posts and post nuts are not.

Seems that if you solder to the back end of these and use the couloured plugs above then you are running without any iron in the loop.

[001]

Why You call it "gold plated"?

It is only shine like a gold but it is not gold anyway
It can be coated with titanium oxide or something else IMHO
What is we reason to use this oxide-coated contacts in metrology?

[beanflying]

And part of the reason NOT to buy Chinese origin evilbay Titanium Oxide cutting tools, chances are they are 'gold plated' too 


https://www.finishing.com/375/26.shtml 

[001]

Is it china bananas have identical "goldlike" TiO covering to china drill bits? 

It is OXIDATION covering. Is it good conductor for measurings?

[cdev]

I wonder if the "gold plated" SMA (RF) connectors Ive been buying recently are in reality titanium oxide coated?

They take solder quite well so i've been assuming that its real gold plating..

If it was titanium, I doubt if it would conduct very well, silver would likely be far better.

[001]

It is very interesting to know what this "gold" in fact
But extra cheap "gold" rca connectors is easy soldered too

[Muttley Snickers]

Slightly off topic as I wasn't sure where to ask, has anyone recently purchased or reviewed a set of these cheaper kelvin leads pictured and linked below, they appear similar to the quality Pomona set also pictured but obviously I expect they would not be in the same league, I need a couple of sets but nothing fancy and they don't look too bad considering the price.

Random Ebay listing.
https://www.ebay.com.au/itm/LCR-Meter-Test-Leads-Lead-Terminal-Kelvin-Clip-Wires-for-UT612-UT611/332008183641?

[martinr33]

They surely look nice, and that looks like gold plating. The problem is, the clips might be brass (most likely) or steel underneath. My experience is that these are pretty much never copper. I have a box of nice-looking inexpensive connectors from multiple suppliers that are gold plated and claim to be copper, but have only found two suppliers of plated copper connectors. You have to grind off a bit of the plating to see the color of the metal underneath.

Some of them are pot metal - a cheap zinc alloy.

[001]

I have some cheap "gold plated" bananas and jacks for about 8 years
And few tips became muddy or pale (probably from fat of the hand skin)

[Mickle T.]

Some of my old thermal EMF measurements (relative to copper, dT=100 C. deg.):

[zhtoor]

hello Mickle T.,

what is the gadget on the left of the picture, constant pressure against copper bus-bar?

also can you measure contact thermal emf of a 1cm^2 piece of copper-clad pcb against another copper-clad pcb?
would that be a viable poor-man's low thermal emf connection?

regards and keep up the good work.

-zia

[Mickle T.]

The gadget on the left of the picturea is a lab. device for measuring the Seebeck coefficient: heaters, thermocouples, ovenized uV amplifiers, PIDs, ADCs e.t.c.

[Awesome14]

It shows the current coming out of an LED from ambient light shining on it.

Glass diodes and LEDs are also passive photovoltaic devices. 

[Gyro]

Well... Active semiconductor devices actually.

[beanflying]

Evilbay at work again. I got these in for a non metorology use but interesting lack of consistency. All the bits on the right of photo 1 are magnetic and with a little closer inspection all the positive banana posts are made with an IRON based washer (2 piece pressed together)  at the base and not brass like the others (single piece cast brass) in the same bag 

The rest of the Positive post appears to be plated brass after a little grinding and sparks from the washer