TNC Plug for LMR-240 — Field Termination Kit
The AMPHENOL RF 031-6826 is a TNC plug, male pin, designed specifically for LMR-240 cable. It ships as a two-piece kit: the connector body and a protective cap, ready for field termination. The TNC interface is threaded, giving a more vibration-resistant mate than a BNC, while maintaining 50 Ohm impedance up to 6 GHz.
Cable Prep and Termination Sequence
Termination is a hybrid: the center contact is soldered, the shield is crimped. For LMR-240, this means stripping the jacket and dielectric to expose the center conductor for solder, then folding the braid back over the prepared cable jacket for the crimp ferrule. The shield termination is crimped, not soldered — that avoids heat damage to the foam dielectric that LMR-240 uses. The threaded coupling nut ensures the interface stays tight under vibration, which is the main reason to pick TNC over BNC in a mobile or industrial RF link.