Abstract: A self-locking electrical connector is disclosed in which a locking ring is mounted in an annular groove in the interior of a coupling nut on the plug of the connector. When the plug is mated with the receptacle, inwardly extending projections on the locking ring ride up over a low-angle ramp on the shell of the receptacle and then snap into a locking groove formed in the receptacle shell behind the ramp to lock the connector members together. The surface of the locking groove next to the low-angle ramp is formed as a high-angle ramp which allows removal of the projections of the ring from the groove when the coupling nut is rotated with high torque to unthread from the shell. In an alternative embodiment, the locking ring is carried by the receptacle shell, and the locking groove and angular ramps are formed on the inner surface of the coupling nut.