MCX Plug for 75-Ohm Cable Assemblies
The 919-421P-71S12G: It covers DC through 12 GHz, making it suitable for video, broadcast, and high-speed data links where 75-Ohm infrastructure is standard. The snap-on coupling gives a positive lock without requiring a threaded collar, which speeds up field mating and unmating in dense patch panels. The centre pin is brass with gold plating; the body is beryllium copper and brass with a gold finish. Gold-over-brass on the centre contact and gold on the body give this plug corrosion resistance and stable contact resistance over repeated matings — the rated 500 mating cycles reflect that plating grade. The PTFE dielectric holds its dielectric constant across that span, so the 75-Ohm impedance stays consistent through temperature swings.
This plug is specified for Belden 4855R cable, a 75-Ohm precision video coax. For the harness builder: the ferrule in the kit matches the cable jacket diameter of 4855R; using a different cable group will change the crimp die and may shift the impedance match. Stick with the listed cable group unless you verify the dielectric diameter and centre conductor gauge against the contact and ferrule dimensions.