RF and Coaxial Connectors Explained: PL-259, N-Type, BNC and SMA
A bloke once walked in with a perfectly good dual-band radio, a new length of coax and three adaptors screwed together like a little brass sculpture. None of it was doing quite what he expected. The antenna had an N-type socket, the radio wanted a PL-259, and somewhere along the way he'd added a BNC adaptor because it looked close enough in the online photo. It fitted. Sort of. The receive side sounded weak, his SWR reading wandered, and touching the adaptor stack changed the result. Naturally, the radio got blamed first. Most people don't think much about coaxial connectors until the signal drops out. They're small, inexpensive compared with the radio, and often bought at the end of a project when patience and budget are both running low. Yet that little joint between the radio antenna cable and the equipment has to preserve the shield, maintain solid centre-conductor contact and carry RF without introducing an ugly impedance change. It also has to survive movement, vib...