I looked at hard-wiring a Hi-5 to a motor controller using an LBUS cable and I was told there was a limit to how long the LBUS could be (50ft I think). I did some further investigating and someone showed me these adaptors (see photo below) that allow you to connect the antenna socket of the Hi-5 to the antenna socket of the UMC via a BNC cable. You put the radio module on the Hi-5, then unscrew the antenna from the radio module and screw in the BNC adaptor. At the other end you just unscrew the antenna from the UMC and screw in another adaptor, then connect the two with a BNC cable. I was told it works with a BNC more than 200’ long so that seemed to be a better (and cheaper) solution than LBUS cable. I bought some of these adaptors (they’re called reverse polarity SMA to BNC connectors) and, very strangely, they seem to work perfectly when the end of the BNC cable is just lightly touching the adaptor but they stop working as soon as you screw the two together properly! I’ve tried several adaptors and several BNC cables and it’s always exactly the same. Can anyone explain?

Thanks!