The 31-5137-RFX: The center contact is gold-plated brass, and the body is zinc die-cast with a nickel finish. This plug is part of Amphenol's broad BNC series, built for RG-58, RG-141, RG-303, LMR-195, and Belden B7806A/9907 cables — the cable group compatibility is the primary selection criterion for field use.
The 4 GHz upper frequency limit covers most commercial and industrial RF bands (Wi-Fi, cellular, ISM) but not higher microwave bands. The 0.2 dB insertion loss is low for a BNC plug, meaning minimal signal power is lost through the connector — important for sensitive receiver paths or long cable runs. The 500 mating cycles rating reflects the gold-plated center contact; this plug is suited for test equipment or field-service applications where connectors are frequently disconnected and reconnected.
This plug is designed for RG-58, RG-58A, RG-58B, RG-58C, RG-141, RG-303, LMR-195, Belden B7806A, and Belden 9907 cables. The contact termination is push-on (crimp-style center pin), and the shield is terminated by twisting the braid over the ferrule — a standard field-installable method. Note: RG-59 cable (75 Ohm) is not listed in the compatible cable group; using it would create an impedance mismatch and degrade signal integrity.