Possible low thermal emf connectors?

[Alex Nikitin]

Here:

http://www.ebay.com/itm/321910325427?

http://www.ebay.com/itm/221473914725?

As I've just bought the Keithley 181 without the input lead, I would need to connect to it somehow. Are these CuTe XLRs are a possible option? It looks like it should be possible to crimp the wires and if these use truly tellurium copper contacts, it might be OK for the K181, replacing the input connector and making a cable and a shorting link?

Cheers

Alex

[TiN]

I always somewhat reluctant for these audiophoolery-grade stuff. Even if it's truly copper, it's just feels sponsoring whole foolery industry instead.

Perhaps you can try your luck with LEMO 1S, like ones used in 2182/34420 (except those are copper version of them).

[Alex Nikitin]

I always somewhat reluctant for these audiophoolery-grade stuff. Even if it's truly copper, it's just feels sponsoring whole foolery industry instead.

Perhaps you can try your luck with LEMO 1S, like ones used in 2182/34420 (except those are copper version of them).

What is the point if these nice LEMO are not copper? And I have to admit that I was part of that very industry for over twenty years  . One of my amplifiers did get "Class A" recommendation in Stereophile magazine at that time (and I have some other awards as well). Perhaps for that reason I am not inclined to dismiss it, but would rather use that industry for something I'm interested in now  .

Cheers

Alex

[Echo88]

LEMO doesnt specify the used connector for the 2182. Seems the best copper contacts they can provide are beryllium copper contacts, not tellurium copper.

[manganin]

I always somewhat reluctant for these audiophoolery-grade stuff. Even if it's truly copper, it's just feels sponsoring whole foolery industry instead.

Audio power cords made of pure silver? (For some reason the visible short length from the wall socket to the amplifier is very important, but no one cares about all the "low grade" cable hidden inside the wall.)

What is the point if these nice LEMO are not copper?

The original Keithley connector is not copper either and there are soldered connections in the signal path inside the meter as well.

The contact material is not important if you keep the connections symmetrical and protected from the temperature gradients.

[Kleinstein]

Pure copper is to soft to be very practical. So to make is harder one has to add something like tellurium or beryllium ( or less common chromium). In both cases thermal EMF does not change very much. To protect the surface often a gold flush us used. As the gold layer is very thin, there will not be a significant temperature difference across it.

Audio cables tend to use oxigen free copper - this is adding phosphorus to the copper to catch any oxygen. So this is not pure copper either.

I one used thermocouples with LEMO connectors. They were mechanical nice, but not very low EMF - so a visible voltage if there was a gradient in the connector area. So I would be a little reluctant with those. If protected they were ok down to the < 100 nV range.

[Alex Nikitin]

The original Keithley connector is not copper either and there are soldered connections in the signal path inside the meter as well.

The contact material is not important if you keep the connections symmetrical and protected from the temperature gradients.

The service manual mentions some cadmium solder in a repair kit to replace the input socket... . I probably would just crimp the wires.

Cheers

Alex

[Vgkid]

The service manual mentions some cadmium solder in a repair kit to replace the input socket... . I probably would just crimp the wires.
Cheers
Alex

In the newer ones, they use 96/4 solder.

[VintageNut]

I would not modify the input connector. I bought a KE147 that the seller had replaced the input connector because the cable is so expensive. His replacement connector and cable was almost useless.

Fortunately he was able to find the original connector and send it to me. I have one of the original cables and it is 10X better than the replacement cable that the previous owner used.

If there were a better input connector or a cheaper one that is just as good, Keithley would have used it.

You can still buy the cable that is used for the KE147, 148, 150B, 181 etc etc. It is not cheap but it is a very good cable.

Here:

http://www.ebay.com/itm/321910325427?

http://www.ebay.com/itm/221473914725?

As I've just bought the Keithley 181 without the input lead, I would need to connect to it somehow. Are these CuTe XLRs are a possible option? It looks like it should be possible to crimp the wires and if these use truly tellurium copper contacts, it might be OK for the K181, replacing the input connector and making a cable and a shorting link?

Cheers

Alex

[acbern]

Keithley, as well as Keysight, use copper contacts (i.e. tellurium copper, as they are lated/milled), without gold flash. These are custom Lemo connectors, not available in the Lemo standard catalog. The 181 and 182 uses standard connectors, MIL type, but these meters are also lower resolution/accuracy, perfectly fine here.
The chinese connectors mentioned look very nice, teflon used also for good insulation. It would be worth while testing them. And despite the fact that I hate the audio foolery too, I would think they are nice metrology connectors, but do not contribute anything to audio quality.

[Alex Nikitin]

The 181 and 182 uses standard connectors, MIL type, but these meters are also lower resolution/accuracy, perfectly fine here.

Thank you. Do you know the exact part number for the matching plug? That would be very helpful.

The chinese connectors mentioned look very nice, teflon used also for good insulation. It would be worth while testing them. And despite the fact that I hate the audio foolery too, I would think they are nice metrology connectors, but do not contribute anything to audio quality.

I've ordered a couple, let's see how it turns out.

Cheers

Alex

P.S. - It looks like Sn10Pb90 solder is used for low thermal EMF joints on pure copper, as a replacement for the Cadmium solder. Any experience with that solder here?

[acbern]

A mating connector is the MS3106A16-11P, and clamp 3057-1008 from Amphenol. These may also be available with gold plating, you may wish to check with Amphenol. They are also available from other vendors. The 181 uses tin plating iirc, the 182 gold. If you find a gold-plated version, maybe you list it here for all the others (including me).

[VintageNut]

Keithley, as well as Keysight, use copper contacts (i.e. tellurium copper, as they are lated/milled), without gold flash. These are custom Lemo connectors, not available in the Lemo standard catalog. The 181 and 182 uses standard connectors, MIL type, but these meters are also lower resolution/accuracy, perfectly fine here.
The chinese connectors mentioned look very nice, teflon used also for good insulation. It would be worth while testing them. And despite the fact that I hate the audio foolery too, I would think they are nice metrology connectors, but do not contribute anything to audio quality.

The 147 and 148 are higher resolution and accuracy than any digital nanovoltmeter ever produced. The 2182A uncertainty is 40nV. The exception to this assertion is the 1801 which is pretty much unobtainable. 

[3roomlab]

has anyone tried to spot weld yet? seems like the best alternative in not adding any solder? the kind used for welding battery linkers?
a good tack, then add a good bulk of solder to improve rigidity

[David Hess]

The service manual mentions some cadmium solder in a repair kit to replace the input socket... . I probably would just crimp the wires.
Cheers
Alex

In the newer ones, they use 96/4 solder.

We ran some tests over on the volts-nuts list and Sn64Ag4 was no better than any other common solder.

Update: Whoops, I meant Sn96Ag4.  I randomly acquired a whole spool of it more than a decade ago and recently had my hope that it was low EMF dashed.

[Vgkid]

The service manual mentions some cadmium solder in a repair kit to replace the input socket... . I probably would just crimp the wires.
Cheers
Alex

In the newer ones, they use 96/4 solder.

We ran some tests over on the volts-nuts list and Sn64Ag4 was no better than any other common solder.

Yep, those post were interesting. To bad the VN list has been kind of dead lately.
Calling for that solder would help keep things consistent.

[Alex Nikitin]

We ran some tests over on the volts-nuts list and Sn64Ag4 was no better than any other common solder.

Anything on the Sn10Pb90 ?

Cheers

Alex

[Vgkid]

We ran some tests over on the volts-nuts list and Sn64Ag4 was no better than any other common solder.

Anything on the Sn10Pb90 ?

Cheers

Alex

Look into the vn archieves of June/July/October 2016.

[ManateeMafia]

From my email with Data Proof, before I replaced the old cables, they recommended SN63PB37 solder. They wrote that they had good results with it.

I would guess that they have already been down this road and they specifically mentioned that they didn't see any additional benefits with cadmium based solder.

[Vgkid]

https://www.febo.com/pipermail/volt-nuts/2016-July/subject.html
https://www.febo.com/pipermail/volt-nuts/2016-June/subject.html
https://www.febo.com/pipermail/volt-nuts/2016-October/subject.html

[Alex Nikitin]

https://www.febo.com/pipermail/volt-nuts/2016-July/subject.html
https://www.febo.com/pipermail/volt-nuts/2016-June/subject.html
https://www.febo.com/pipermail/volt-nuts/2016-October/subject.html

Thank you, it looks like the Sn10Pb90 was not tested. I should get some soon and will try it, comparing with Sn60Pb40 and Sn96Ag4Cu1 . If it measures well, I'll be happy to share some for a price of postage, as I've bought 5lb reel  . I've also ordered a couple of plugs for the Keithley 181, hopefully correct ones... .

Cheers

Alex

[VintageNut]

I look forward to seeing the results of your DIY cable efforts.

https://www.febo.com/pipermail/volt-nuts/2016-July/subject.html
https://www.febo.com/pipermail/volt-nuts/2016-June/subject.html
https://www.febo.com/pipermail/volt-nuts/2016-October/subject.html

Thank you, it looks like the Sn10Pb90 was not tested. I should get some soon and will try it, comparing with Sn60Pb40 and Sn96Ag4Cu1 . If it measures well, I'll be happy to share some for a price of postage, as I've bought 5lb reel  . I've also ordered a couple of plugs for the Keithley 181, hopefully correct ones... .

Cheers

Alex

[Squantor]

Same here. I have a 150b without a cable, I have been contemplating to replace that cannon input connector with something more available. Unfortunately the manual states that I need to solder specific connections with cadmium solder. There is even a small spool of it in the amplifier section! Reminds me of the vintage tek oscilloscopes that carried the silver solder inside for repairs.

Maybe talk here at work on using one of the fume hoods in off work.

I look forward to seeing the results of your DIY cable efforts.

[VintageNut]

I have a spool of the same solder that was in the same place as yours. I would use it outside in warm weather as an afternoon soldering project. Fortunately I have one of each of the cables. One has spade lug ends and the other has alligator ends. A third one came with the 150B and was hacked by a previous owner. The ends are just flying wires with the connectors missing. I bought the 150B just for the cable that was pictured in the auction.

Same here. I have a 150b without a cable, I have been contemplating to replace that cannon input connector with something more available. Unfortunately the manual states that I need to solder specific connections with cadmium solder. There is even a small spool of it in the amplifier section! Reminds me of the vintage tek oscilloscopes that carried the silver solder inside for repairs.

Maybe talk here at work on using one of the fume hoods in off work.

I look forward to seeing the results of your DIY cable efforts.

[Kosmic]

Hi,

This is my take on the Keithley 181 DIY test lead.

I used:
- Amphenol MS3106A16-11P connector
- Amphenol 97-3057-1008-621 Backshell connector
- 4 feets of PTFE cable (shielded, silver plated, 20awg)
- Copper alligator clip
- Sn10Pb90 Solder

Did a quick test with limited air draft protection, clip shorted on the 2mV range, I'm sitting at -60 nanovolt. Nevertheless, my 181 is out of call and he is probably off.