Quality judgment of communication cables

How to judge the quality of communication cables

1. Check the weaving of the shielding layer: is the weaving enough? Copper mesh, check the solderability, scratch the tinned copper computer 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 mesh is sparse, the distribution is uneven, and the insulation layer is not tightly wrapped, etc. Poor cable; use a lighter to burn the core wire, if it is copper-clad aluminum, it is easy to see that the inner color is different from the outer copper; peel off the outer skin, and look at the braiding angle of the shielding layer, if it basically stands up, then the basic It can be seen from the above that the weaving angle is relatively large, which is a product of cutting corners;

2. PVC sheath: It can be seen on the surface that there are regular "unevenness" of the braided net inside the compression, indicating that the processing technology is good and there will be no relative sliding, so it is a good cable. The appearance is smooth, and the "unevenness" of the compressed braided network cannot be seen, and the sheath feels loose when pinched by hand, which is a poor cable;

3. Check the bonding force between the core wire and the insulating layer: cut the insulating layer obliquely, pull the core wire according to the peeling direction, and see if the core wire and the insulating layer are bonded to the process material; good cables have greater bonding force, poor The cable is not bonded;

4. Check the core wire: diameter——SYV cable is 0.78-0.8mm, SYWV cable is 1.0mm; a cable with SYV75-5 core wire diameter of 1.0mm has appeared recently, and the characteristic impedance of this cable is definitely not 75 Ohm, not applied to 75 ohm transmission system; use a vernier caliper to check the diameter of the inner core of the cable;

5. Longitudinal tensile test: Take a one-meter security cable, peel off the core wire, insulation layer, shielding layer, and outer jacket layer by layer, leaving 10 cm long each. The method is: hold the two adjacent layers of the cable with two hands, and pull them in opposite directions; good cables cannot be pulled with general strength, and poor cables can be easily pulled out without much effort.

6. Unwrap a roll of wire to measure the length, or roughly judge by weighing;

Solutions for purchasing communication cables

1. If the transmission distance exceeds 800 meters, use the SYV-75-5 cable and find that there is no image or the image is jumping, you can use the video amplification anti-jamming device, which adopts the video segmentation amplification method, which can amplify the video signal by 10 times , so that the transmission distance can be effectively extended (a simple amplifier cannot be used, otherwise the signal loss will be great);

2. If several cables interfere with each other, multi-signal multiplexing equipment can be used to transmit 8 channels of video images and control signals simultaneously in one video cable;

3. If you encounter the problem of cable welding, it is recommended to buy pure tin solder wire, and use a high-power soldering iron for fast welding, and you must not slowly tin;

4. Finally, if you are not sure about video cables, you can also use radio frequency cables to transmit multiple video signal equipment. One radio frequency cable can transmit 20 channels of image and control signals at the same time. The transmission range can reach 3 kilometers, so the cost will be more cost-effective.

The above is how to judge the quality of communication cables for everyone. Engineering companies must keep their eyes open and carefully identify the advantages and disadvantages of cables..