The 031-70221: The 75 Ohm characteristic impedance tells you this is a video-grade BNC — not the 50 Ohm variant used in RF test equipment — so it pairs with RG-59, RG-6, and similar 75 Ohm cable types. Rated to 3 GHz maximum frequency, it covers standard-definition, HD-SDI, and 3G-SDI signal paths without the insertion loss penalty you'd see pushing a 50 Ohm BNC past 1 GHz on a 75 Ohm line. The right-angle through-hole termination with bulkhead front-side nut mounting lets the connector sit flush against the panel face while the PCB-mount pins route parallel to the board. That orientation saves depth in shallow enclosures — broadcast switchers, video patch panels, and camera interface boxes where the rear panel is tight against the chassis wall. The kit includes the lockwasher and nut, so the panel cutout is the only additional prep needed. The PTFE holds its dielectric constant across temperature swings, which keeps the 75 Ohm impedance stable when the connector is in an outdoor broadcast truck or an unheated equipment shed. The nickel-plated brass body handles the ground return and the bayonet lock gives a positive mechanical mate that won't vibrate loose under fan or vehicle vibration.
75 Ohm vs 50 Ohm — the Impedance Choice Drives the Signal Path
The 75 Ohm impedance of the 031-70221 is the primary selection gate. A 50 Ohm BNC like the 031-5329-52RFX will physically mate with the same bayonet lock and panel cutout, but the impedance mismatch at the junction creates a reflection that degrades the signal above a few hundred MHz. For video baseband and digital video up to 3 GHz, the 75 Ohm path is the correct one. The 031-70016 is the same 75 Ohm impedance but uses crimp shield termination instead of solder — choose the 031-70221 when you want a soldered shield connection for field reliability or when the cable jacket won't accept a crimp ferrule.