About banana plugs

[Sbampato12]

Hi everyone,

I'm restoring a Yokogawa resistance decade box, wich was in a junkyard (  ), so it was in a really bad state outside, but the inside, and the rotary switches are ok.
The question is, about the banana plugs, they are very bad, I don't think it is worth to try to clean then. So I will order some new, but I want to get some nice pieces, but when looking for them, I encountered many tipes of base materials.
On Farnell/Newark (http://www.newark.com/CategoryDisplay?storeId=10194&urlLangId=-1&urlRequestType=Base&categoryId=800000030002&langId=-1&catalogId=15003) there are for example: Beryllium Copper, Brass, Bronze, Copper, Phosphor Bronze and Steel. With Gold, Nickel, Silver or Tin Plating.

And my doubt is, wich is better? There are one more indicated for each use? one better overall?

Thanks in advance!

[robrenz]

What is the lowest resistance setting and does it have 4 wire connections?  This will affect how important the jack materials are.

[Sbampato12]

The lowest resistance is 1 ohm. And it hasn't 4 wires.

[robrenz]

What is the stated accuracy of the unit?  Since it does not have 4 wire yet has 1 ohm I suspect that it is not a real high accuracy. Gold direct on copper jacks is probably the best.  Brass jacks will have higher resistance than copper and may shift the low ohms out of spec. (Assuming it used copper to begin with)  Don't worry about seeing Telurium in the copper It is only for machinability not electrical properties.

[Sbampato12]

Yeah, these doesn't need to be a high precision, due the box itself its a little old, but I thought it was better to ask before...

And as I saw so many options, I get curious about they. But your explanation was enough for me, and I've got the ideia.

Thanks!

[Fsck]

What is the stated accuracy of the unit?  Since it does not have 4 wire yet has 1 ohm I suspect that it is not a real high accuracy. Gold direct on copper jacks is probably the best.  Brass jacks will have higher resistance than copper and may shift the low ohms out of spec. (Assuming it used copper to begin with)  Don't worry about seeing Telurium in the copper It is only for machinability not electrical properties.

actually, the tellurium reduces electrical properties slightly. something like 5-8% reduction of conductance.

[robrenz]

Correct.  Many think Telurium copper is some "magic low thermal EMF alloy" that is superior to generic copper, it is not. It is electrically inferior but is much more machinable which is important on a machined product like a banana jack.  Pure copper has a machinability rating of 20 and Telurium copper has a rating of 80. this is based on free machining 360 brass being 100.
So even though it is possible to machine banana jacks from pure copper it would not be fun and they would cost at least three times as much.

[Sbampato12]

These last two posts, very good. That was the kind of information I was trying to find.
Thanks a lot!