Tiny XLR wire gauge

[Keith Graham]

Hi,

I am making a cable for the new Lhires upgrade. I have the tiny XLR female connector and tried 18 gauge wire, but soldering that wire size was not very successful for my limited soldering experience (too thick). I experimented with some 20 gauge speaker wire I had and it worked much better. I will need to order up some 4 conductor cable, but I would like to know if I can use 22 gauge wire. That would appear to be ideal for me, but would that be too fine a wire for this purpose or should i stick with 20 gauge?

Thanks,

Keith Graham

[Paolo Berardi]

Hi Keith, waiting answers from more experienced people (I don't know gauge numbers), I would recommend the use of heat shrink for each contact to ensure proper isolation. Indeed the pins are very close together.

Paolo

PS: electric current should be very low for Lhires III operations so I would expect that the wires may be also thin.

[Keith Graham]

Thanks Paolo,

Actually, I saw on your website the setup you made for remote operation of the LHires. I also saw that cable that I am making. Do you remember the wire size you used for that? Also, a good point about the heat shrink. I had not thought of that, but it is certainly a great idea. I do have some and will use it.

Cheers,

Keith

[Paolo Berardi]

Hi Keith, I just did a check in observatory, unfortunately the cable has no brand or writing on it. I didn't remember the internal wires size (I used the entire cable, now carefully isolated in both connectors). External diameter measures 4.5 mm and cable is shielded (I do not use the ground) with four wires inside. But I realized that it is an insufficient information...

Anyway, a good starting point would be to know the maximum current required by the spectroscope. I hope someone from Shelyak may provide the data.

Paolo

[Keith Graham]

Hi Paolo,

Just for information purposes, I did use a very fine tip on my soldering iron. The 18 awg stranded wire was quite stiff and difficult to position and solder onto the small contacts. I actually boogered up the connector so badly that I had to order a new one. Even with very tight twisting and even removing some of the strands, the wire was still quite bulky for those small contacts on the connector. I had some 20 gauge speaker wire that I experimented with and that worked much better. Problem is I cannot find small amounts (10-25 ft) of 20/4 wire anywhere, even on Ebay. I did find 25 ft. of 22/4 wire. I believe that size should be good enough for the Lhires purposes, but I wanted to be sure before proceeding with the 22 gauge. So if anyone else has made this cable, it would be helpful to know what wire size was used and if 22 awg would be sufficient.

Cheers,

Keith

[Robin Leadbeater]

Hi Keith,

I just checked the current drawn by my ALPY calibration module which I expect is similar. The control lines take very little current (a few mA) and the maximum current carried by the main 12v supply is 470mA with the flat lamp on. Based on this, if you know the resistance/unit length of your 22awg stranded wire you could calculate the voltage drop.

Robin

EDIT: looking here
http://www.bulkwire.com/wireresistance.asp
I would say 22awg would be fine unless you are planning a long cable run > 5-10 m say

[Keith Graham]

Thank you for that great explanation, Robin. I had not considered that resistance factor, but of course it makes perfect sense to figure in the length of the wire. Actually, my cable length will be about 3 meters, so all should be good with the 22 awg sire.. I do appreciate your help.

Cheers,

Keith