RADIO-FREQUENCY CONNECTOR. PART 21: TWO TYPES OF RADIO-FREQUENCY CONNECTORS WITH INNER DIAMETER OF OUTER CONDUCTOR 9,5 MM (0,374 IN) WITH DIFFERENT VERSIONS OF SCREW COUPLING. CHARACTERISTIC IMPENDANCE 50 OHMS (TYPES SC-A AND SC-B). (Endorsed by AENOR in June of 1998.)