What This BNC Shorting Cap Does
The Amphenol RF 031-17 is a BNC shorting cap — an accessory that terminates a BNC jack by shorting the center contact to the outer shield. It is used to ground unused ports on RF distribution panels, test equipment, or patch bays, preventing signal reflections and keeping the line impedance stable. The cap fits standard BNC jacks and is secured by the bayonet coupling, with a chain attachment (listed as a feature) to keep it tethered to the panel so it doesn't get lost during service.
Construction and Finish
The body is machined brass with a nickel finish, giving it corrosion resistance and a consistent ground path to the jack shell. The center contact is also brass with a silver finish — silver provides low contact resistance and good RF conductivity at the shorting interface. The cap is silver in color, matching the standard nickel finish of most BNC jacks. It ships in bulk packaging.
Compatibility Note
This cap is designed for use with BNC jacks. It is not a 75-ohm terminator — it is a shorting cap, meaning it creates a DC short between center and ground. For 75-ohm systems requiring a matched termination, a dedicated 75-ohm terminator is needed instead. The cap works with both 50-ohm and 75-ohm BNC jacks mechanically, but the electrical function (shorting) is the same regardless of system impedance.