IEC 60169-16 Amd.1 Ed. 1.0 b:1996

Amendment 1 - Radio-frequency connectors. Part 16: R.F. coaxial connectors with inner diameter of outer conductor 7 mm (0.276 in) with screw coupling - Characteristic impedance 50 ohms (75 ohms) (Type N)

International Electrotechnical Commission , 03/07/1996