Use sweetcorn - it has a higher latent heat figure so will stay frozen for longer!

I got a small piece of CW1724 cable from eBay (think it was external cable) and used two RJ12 connectors and crimped it myself. Kept the cable short 50cm. Works great. CW1724 is basically CAT5E but with 2 pairs instead of 4, so easier to crimp.

Edited by deleted (Fri 11-Sep-20 21:14:47)

For what it’s worth you may as well run it in Cat 5E as it’s a higher specification of cable rather than CW1308 (which is more or less like the old Cat 3).

If “noise“ is troubling you, stick it in some earthed Kopex or galv coinduit, but then again it’s only a tiny bit of the whole link back to the cab...

In reply to a post by MrSaffron:

Solid gold single core stranded cable with cooling jacket to -170 degrees C

Any audiophile would be able to tell you that gold would make a [censored] poor cable. Copper has a conductivity of 5.96×10⁷ S/m at 20°C. for gold this is only 4.11×10⁷ S/m. That is significantly worse. If you want better then you go to silver which has the best conductivity of all metals 6.30×10⁷ S/m. You use gold to plate contacts because it does not oxidize and there is a trade off between surviving more insertion events with a thicker coating compared to it's higher resistance the thicker the coating.

For a low temperature superconductor then niobium-titanium would be the material of choice, For a high temperature supercondutor then yttrium barium copper oxide (YBCO) tapes are used. However none of these superconduct at -170°C. I would note that as long as you can cool it with liquid nitrogen the actual temperature at which it super conducts is largely a willy waving contest and things like current density and critical magnetic field strength are much more important than critical temperature.

Lanthanum hydride does superconduct at -23°C which would put it firmly in the realm of dry ice cooling. However it requires a pressure of 170 gigapascals which is even less practical that liquid nitrogen cooling.

The best idea is to use as short as possible a piece of wire and convert it ethernet as soon as you possibly can.