Coax of woe

Anyone who even vaguely knows me will know that I have certain issues with small coaxial cables. I’ve tried various varieties of coax and connector to wire the fridge for the low temperature, low noise experiments. However I’ve always had failures due to these coaxial lines just being too complicated (too tiny, too many filters, connectors, etc running down the length of them). The previous coax I used was a 0.3mm stainless steel variety, as I mentioned in an earlier post. I have also tried flexible braided stainless steel coax (which also have the issue of the difficulty of soldering to stainless), and twisted pair, in which case I connected the filters to the twisted pair using small pins, which was a mistake as too many solder joints mean that again they are likely to fail.

Well I’ve just installed some new 0.5mm CuNi coaxes. These are much easier to solder to, and easier to work with in general (they don’t break every time you breathe on them) so we’ll see how they go, I’m going to cool them down today.


2 thoughts on “Coax of woe

  1. UHV says:

    How did the CuNi coaxes work? What is your base temperature. We have a devil of a time using stainless steel.

  2. physicsandcake says:

    I’m still using the CuNi coaxes and they seem to work OK upon thermal cycling, although you still have to be careful when installing them not to bend them too much or they’ll break at the join to the connector. The base temperature of the fridge is about 40mK. The stainless steel ones were awful; they repeatedly failed. I’d really avoid them if possible.

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