Japanese coaxial cable specifications, from thin and thick, there are 1.5C, 2C, 3C, 4C, 5C, 3D, 4D , 5D and other cable diameter distinction .

Such as "3"refers to the outer diameter of the cable is about 5.4 mm, “5”refers to the outer diameter of the cable is about 7.4 mm, “C” refers to the impedance of the cable is 75 ohms, D refers to the impedance of the cable is 50 ohms . Does that make sense to you ? 

In the commonly used 5C-FB, F refers to translucent foamed PE polyethylene insulation, B refers to Braiding . Expanded polyethylene insulated vinyl sheath coaxial cable for satellite television reception . 

For coaxial cable, its grade is not as good as 5C-2V/CS; 2 refers to Solid PE insulation; CS means that the central conductor is copper-covered steel wire;

5C-2V/S, S means that the central conductor is copper stranded wire, 5C-FB,

RG/6-U stands for High frequency Official use Radio frequency Government,

Universal specification coaxial cable with 18 AWG 1.02 mm square conductor, foamed polyethylene Foam PE insulation, hot melt aluminum foil and double aluminum wire braided isolation .

So you can see , actually there is not much difference in international standard and Japanese standard from inner structure , You can find the latter is more suitable and right for Japanese market and using according to to their CCTV and CATV system and preference .

Welcome to leave your comments , if you still have a confusion on them !