1. PVC sheath: On the surface, you can see the regular "unevenness" of the compressed mesh inside, indicating that the processing technology is good and there will be no relative sliding. It is a good cable; the appearance is smooth, and you can't see the "unevenness" of the compressed mesh. "Unevenness", the sheath feels loose when pinched by hand, it is a poor cable.
2. Check the braiding of the shielding layer: whether the number of braids is enough, braid the copper material, check the weldability, scrape the tinned copper wire to see if there is copper wire inside, the hardness of the aluminum-magnesium alloy wire is obviously greater than that of the copper wire; the braiding is sparse, Uneven distribution, loose insulation, etc. are bad cables.
3. Check the core wire: diameter---SYV cable is 0.78 to 0.8mm, SYWV cable is 1.0mm; recently a SYV75-5 cable with a core wire diameter of 1.0mm has appeared. The characteristic impedance of this cable is definitely not 75 ohm, should not be used in 75 ohm transmission systems.
4. Check the adhesion between the core wire and the insulation layer: cut the insulation layer diagonally and pull the core wire apart according to the peeling direction to see if there is any bonding process material between the core wire and the insulation layer; good cables have greater adhesion, and poor cables No gluing.
Longitudinal tensile test: Take one meter of cable, peel off the core wires, insulation layer, shielding layer and outer sheath in layers, leaving 10 cm long each.
The method is: hold the two adjacent layers of the cable with both hands and pull in opposite directions; good cables generally cannot be pulled out with force, but poor cables can be easily pulled out without much effort.
![Singi Cable[Email: singi100@singi.com]](/u_file/2303/photo/11c1fa1eb8.jpg)
