1, PVC sheath: The surface can see the pressure inside the network has a regular "roughness", show that the processing technology is good, will not produce relative sliding, is a good cable, the appearance of smooth, can not see the compression of the network of the "roughness ", with a hand pinch sheath has a loose movement, is the cable.
2, check the shielding layer network: The number is enough, copper wire mesh, check solderability, tinned copper wires scraping inside is not copper wire, aluminum-magnesium alloy line hardness is significantly greater than copper wire, the network sparse, uneven distribution, and insulating layer is not tight, such as cable.
3, check the core wire: diameter---syv cable is 0.78 to 0.8MM,SYWV cable for 1.0mm; Recently, a syv75-5 core wire diameter is 1.0mm cable, the characteristic impedance of this cable is certainly not 75 ohms, not applied to 75 ohms transmission system. 4, check the core wire and insulation layer of adhesion: oblique cut insulation layer, according to the stripping direction of the core line, see the core line and insulation layer has no bonding process material; good cable has a greater adhesion, the cable does not glue.
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Longitudinal tensile experiment: Take one meter cable, layer peel open core line, insulation layer, shielding layer, outer sheath, each leave 10 centimeters long. The method is: Two hands respectively grip the adjacent two layers of cable, pulling in the opposite direction; good cable general strength pull not move, the cable can not be hard to pull out easily.
