TELECOM KNOWLEDGE-Be careful when using RF coaxial cables!

2021-12-03

1. First observe the roundness of the insulating medium

The cross-section of the standard radio frequency coaxial cable is very round. The outer shield of the cable and the aluminum foil are attached to the outer surface of the insulating medium. The more rounded the outer surface of the medium, the smaller the gap between the aluminum foil and its outer surface, and the less round the larger the gap. .
Practice has proved that the smaller the gap, the better the performance of the cable
In addition, the large gap air is easy to invade the shielding layer and affect the service life of the cable.

2.check the consistency of the coaxial cable insulation medium

The fluctuation of the diameter of the coaxial cable insulation medium mainly affects the echo coefficient of the cable. This inspection can cut out the insulation medium of a section of the cable, and carefully check the outer diameter of each point with a micrometer to see if it is consistent.

3.check the quality of aluminum foil

Aluminum foil plays an important role in coaxial cable shielding, which plays an important role in avoiding external open-circuit signal interference and preventing cable TV signal leakage
Therefore, the quality of aluminum foil should be tested for new coaxial cables.
First, cut open the sheath layer to observe whether the surface of the woven mesh cable and aluminum foil layer maintains a good gloss;
The second is to take a piece of cable, wrap it tightly on a small metal shaft, straighten it and turn it in the opposite direction, repeat it several times, and then cut the cable sheath to see if the aluminum foil is broken or not. You can also cut it out. A small piece of aluminum foil is repeatedly rubbed and stretched in the hand, and it is still not broken after repeated rubbing and stretching. The one with a certain toughness is cooperative vomiting, otherwise it is inferior.

4.check the braided net of the coaxial cable

The braided network cable of the coaxial cable plays an important role in the shielding of the coaxial cable, and whether it is in the centralized power supply cable TV line or the return line of the power supply, the quality inspection of the coaxial cable must carefully observe whether the textile network is tight and flat.
The method is to cut off the outer sheath of the coaxial cable, cut a short section of the coaxial cable braided net, and appraise the number of braided nets
If it is in conformity with the given index value, it is qualified. In addition, a single textile network cable is measured with a spiral micrometer. Under the comparison of the same price, the quality of the wire diameter is thicker, the better.

5. Detect the tightness of the outer sheath

The outer sheaths of high-quality coaxial cables are tightly wrapped, which can reduce the gap in the shielding layer, avoid air ingress and cause oxidation, and prevent the relative sliding of the shielding layer from causing electrical performance drift. However, if the package is too tight, it will cause peeling. Head inconvenience, increasing the difficulty of construction.
The inspection method is to take a 1m long cable, peel off the protective layer at the end, and it is appropriate that the core cannot be pulled out with force.

6.observe the shape of the cable loop

The looping of the cable is not only reflected in the beauty and unsightly appearance, but more importantly, the quality of the cable. The cables are looped and flat, each cable is kept on the same concentric plane, and the cables and the cables are in circular arc parallel and overall contact, which can reduce the mutual force between the cables, and the stacking is not easy to deform and damage
Therefore, when checking the quality of the cable, don't just look at it carelessly, but carefully observe it.

Analysis of the development trend of RF front-end