1. Observe the roundness of the insulating medium
The cross-section of a standard RF coaxial cable is very round and smooth. The outer shield and aluminum foil of the cable are attached to the outer surface of the insulating medium. The rounder and smoother the outer surface of the medium, the smaller the gap between the aluminum foil and its outer surface, and the larger the gap if it is less round. Practice has proven that the smaller the gap, the better the performance of the cable. In addition, large gaps allow air to easily penetrate the shielding layer, affecting the service life of the cable.
2. Inspect the consistency of the insulating medium of coaxial cables
The fluctuation in the diameter of the insulating medium of coaxial cables primarily affects the cable's echo coefficient. This inspection involves cutting out a section of the cable's insulating medium and carefully measuring the outer diameter at various points with a micrometer to check for consistency.
3. Check the quality of aluminum foil
The aluminum foil plays a crucial role in shielding within coaxial cables. It is instrumental in preventing external open-circuit signal interference and leakage of cable television signals. Therefore, it is essential to inspect the quality of aluminum foil in newly installed coaxial cables.
Firstly, peel off the sheath layer and observe whether the braided mesh wire and the surface of the aluminum foil layer maintain a good luster. Secondly, take a section of cable, tightly wrap it around a small metal shaft, straighten it, and rotate it in the opposite direction several times. Then, cut off the cable sheath layer to check if the aluminum foil is cracked. Alternatively, cut off a small section of aluminum foil and repeatedly rub and stretch it in your hand. If it remains intact after multiple rubs and stretches, indicating a certain level of toughness, it is considered a qualified product. Otherwise, it is a defective one.
4. Check the braided mesh of the coaxial cable
The braided mesh of coaxial cables plays a crucial role in the shielding performance of the cables. Whether in centralized power supply cable television lines or power return lines, careful observation of the tightness and flatness of the braided mesh is essential for quality inspection of coaxial cables.
The method involves cutting open the outer sheath of the coaxial cable, trimming a small section of the coaxial cable's braided mesh, and assessing the number of braided meshes. If it matches the given indicator value, it is considered qualified. Additionally, a single braided wire is measured using a spiral micrometer. In a comparison at the same price, the thicker the wire diameter, the better.
5. Detect the tightness of the extruded outer sheath
High-quality coaxial cables have their outer protective layers tightly wrapped, which can reduce the gap within the shielding layer, preventing air from entering and causing oxidation, and preventing the relative sliding of the shielding layer from causing electrical performance drift. However, if the extrusion is too tight, it can make it difficult to strip the end and increase the difficulty of construction. The inspection method is to take a 1m-long cable, strip off the protective layer at the end, and ensure that the core cannot be pulled out with force.
6. Observe the shape of the cable coil
Cable looping is not only about aesthetic appearance, but more importantly, it concerns cable quality. When cables are neatly looped, each cable remains on the same concentric plane, and they make circular arc-shaped parallel contact with each other. This can reduce the mutual stress between cables, making them less prone to deformation and damage during stacking. Therefore, when inspecting cable quality, one should not be careless and just take a cursory glance. Instead, one should observe carefully and thoroughly.
