1, check the shielding layer mesh: braid number is enough? Copper braiding, check the weldability, tinned copper wire scraping to see if the inside is copper wire, aluminum-magnesium alloy wire hardness is significantly greater than the copper wire; braided mesh sparse, uneven distribution, and the insulation layer is not tightly wrapped, etc. is poor cable;

2, check the core line and the insulation layer of the adhesion: cut the insulation layer diagonally, according to the stripping direction of the core line, see the core line and the insulation layer there is no adhesion process materials; good cable has a greater adhesion, the poor cable has no adhesion;

3, check the core wire: diameter - SYV cable for 0.78-0.8mm, SYWV cable for 1.0mm; recently appeared a kind of SYV75-5 core wire diameter is 1.0mm cable, the characteristic impedance of this cable, certainly not 75 ohms, should not be used to 75 ohms transmission system.

4, PVC sheath: the surface can be seen inside the compression of the braided network has a regular "unevenness", indicating that the processing technology is good, will not produce relative sliding, is a good cable. Smooth appearance, can not see the "unevenness" of the compression network, pinch the sheath with a loose feeling, is poor cable;

Translated with DeepL