75 Ohm HD-BNC Jack for 18 GHz Signal Paths
The Amphenol 034-1139-12G is a 75 Ohm HD-BNC™ jack, female socket, designed for signal paths that push past the 4 GHz ceiling of standard BNC. Rated to 18 GHz, this bulkhead-mount connector uses a bayonet lock and isolated construction to maintain impedance through the panel interface.
Impedance and Frequency — What the 75 Ohm and 18 GHz Ratings Mean
The 75 Ohm impedance targets video distribution, broadband CATV, and high-resolution imaging systems — not the 50 Ohm world of RF test gear. Mating a 75 Ohm jack into a 50 Ohm line creates a 1.5:1 VSWR bump that degrades return loss at higher frequencies. The 18 GHz maximum frequency is the upper bound of the HD-BNC interface; standard BNC typically rolls off around 4 GHz. For a 3 GHz HD-SDI signal this connector has headroom well beyond the fundamental.
Mounting and Termination — Bulkhead Fit and Solder Connection
Panel mount with a front-side nut through a bulkhead hole, secured by the through-hole solder posts. The shield termination is solder, as is the centre contact — no crimp tooling required. The isolated feature means the connector body is electrically separated from the panel ground, useful where ground loops must be broken.