75 Ohm BNC Crimp Jack for Belden 1794A / 4794R
The 031-70539-12G: This is the 75 Ohm variant of the standard 50 Ohm BNC — the impedance mismatch between a 50 Ohm plug and 75 Ohm cable will cause a reflection at the interface, so matching the connector impedance to the cable is non-negotiable. Rated to 12 GHz with 500 mating cycles, it covers high-frequency video, broadcast, and data applications where signal integrity matters.
75 Ohm vs 50 Ohm — The Impedance Match
The physical interface is identical — both use the same bayonet lock and center contact geometry — but the dielectric and center pin dimensions differ to achieve the target impedance. Using a 75 Ohm connector on a 50 Ohm cable (or vice versa) creates a mismatch that degrades return loss and signal amplitude, especially above a few hundred MHz. For Belden 1794A (75 Ohm) or 4794R (75 Ohm), this is the correct impedance.
Crimp Kit Contents and Installation
The kit ships with four pieces: the BNC jack body, one gold-plated center contact, one crimp ferrule, and one PTFE insulator. The center contact is crimped onto the cable center conductor, the ferrule is crimped over the braid and jacket, and the insulator positions the contact inside the body. The PTFE dielectric provides stable impedance and low loss up to 12 GHz. For Belden 1794A, the crimp die selection must match the cable diameter — the ferrule is sized for that cable group.