MCX Connector MCX connector has smaller size compared with some RF connectors like SMA connector, SMB connector. MCX subminiature snap-on connectors offer a stable and durable connection. The subminiature design allows other electronic assemblies to be densely packaged on the PCB. The MCX uses identical inner contact and insulator dimensions as the SMB,the outer diameter of the plug is 140 inches, which is 30% smaller than the SMB. MCX provides broadband capability though 6 GHz with a snap on connector design. A range of connectors are available, including printed circuit board and cable connectors.