Insulated BNC Bulkhead Jacks A series of professional quality 75 Ω machined BNC connectors from Coax Connectors. These insulated bulkhead jacks all have gold plated phosphor bronze contacts and nickel plated brass bodies. The BNC connectors have a simple bayonet coupling requiring only a quarter turn to connect and disconnect. The simple method of connection makes them one of the most commonly used coaxial cable connectors. This range of connectors can operate up to 4.5 GHz and meet SMPTE 292M and 424M standards.