The ones that I had problems with were on a 235 and a 245. The but wasn't a hex, but was a round one with two notches in it. A similar, but much large version used to be used to hold GM radios in the dash board and you could buy a special wrench to tighten. IIRC, it was called a "spanner" wrench. It would seem that there would be something similar available for the BNC nut, but I've never been able to find one. I'm sure that some sort of specialized tool is used when the scanners are built, as I don't see the production crews using needle nose pliers or small screw drivers to put them together. Of course, that tool is probably pneumatic and costs a couple of hundred dollars. <G>
Gary