BNC Connectors

A BNC connector is an individual plug or socket with a bayonet lock, fitted to a coaxial cable or mounted in a panel, rack or device. In audio and video it is used mainly for SDI video, word clock synchronisation and antenna distribution for wireless systems. Ready-made leads are in BNC cables.

75 Ω or 50 Ω

BNC connectors come in two impedance versions. 75 Ω is the standard for video (SDI, HD-SDI, 3G to 12G-SDI) and word clock, while 50 Ω is used for RF and antenna lines, for example with wireless microphones. The two versions usually mate mechanically, but at high frequencies an impedance mismatch causes reflections and signal loss. The connector impedance must therefore match both the cable and the equipment.

What you are choosing	Typical use	Check before buying
Cable connector	Cable end for SDI video or word clock	Cable type and diameter, termination method
Panel / feed-through socket	Mounting in a panel, rack or patch panel	Mounting hole size and isolated or grounded version
Caps and protective parts	Protection and colour coding of the connector	Size matching the specific connector

Fitting to a cable

A BNC cable connector is always designed for a specific type of coaxial cable – the outer diameter, centre conductor diameter and shield type all matter. Professional connectors are mostly crimped with a dedicated tool, and the centre contact is crimped or soldered. Before buying, check in the manufacturer's specification which cable the connector is intended for.

Bayonet lock

A BNC connection is made by pushing in and turning a quarter turn. It will not come loose when the cable moves or is pulled by accident, yet it disconnects quickly without tools. That is why it is popular in broadcast, on stage and in studios where connections change often.