For my project, I need to have BNC connectors on the test metal shield. So what I did so far is drilling holes, and mounting BNC connectors on it:
I used some hot shring on the part which passes through the hole. Those washers are normal fibre ones. I don't have something better at my arsenal now. This will not be a good insulator, because I measured the resistance from outer bnc connection to the metal shield and it happend to be around 1.4 GOhm:
The problem is, the signal LO (the outer connector of coax cables) should be totally isolated from the metal shield. The best thing I can think of is some sort of teflon washer (shoulder washer) that can pass through the hole of the metal shield and then I can insert the BNC connector through it. Unfortunately I was unlucky to find what I need. What I have found is made from nylon and I think it can not provide a resistance as good as teflon, also it has the problem of absorbing water (humidity) :
Please let me know what you think, and would be nice if you know a place that I can order the required stuff!