The role of CATV protector, and usage
If cable TV is joined or cable Internet is joined, a protector will be installed in the outdoors. The role of this CATV protector and usage were considered.
The role of a CATV protector
The role of a CATV protector is equipment for protecting television and its peripheral equipment. Unusual voltage may be added to the antenna cable of CATV by guidance thunder etc. The high voltage is then missed to the earthing conductor.
The standard of a CATV protector (electrical property)
This photograph is a CATV protector installed in my home. It is an insulated type in 2 distribution type. The output has become those with two line, an object for the Internet, and televisions. After the object for televisions connects booster only for CATV to next, it is distributed to each part store.
The main electrical properties of the common CATV protector for ground-digital-broadcasting reception are as follows.
- Frequency band
- The object for ground digital broadcasting has a 10-770-MHz. As for the thing corresponding to BS, the frequency characteristic is prolonged to 1350 MHz. Generally, it is DC (direct current) cut. There are some which cut 70 MHz or less.
- Insertion loss
- About 0. 5-1 dB. The loss of the distribution and branch is added to distribution or a branched type.
- V. S. W. R. (voltage standing wave ratio)
- About 1. 3 to 1. 7
- Input-and-output impedance
- Insulation of input and output
- Generally, input and output are insulated also including the ground side. There is also a non-insulating thing. Resisting pressure is for 1 minute in AC1,000V.
- Protecte element
- Arrester (surge arrester), fuse, and choke coil -- it is used, independent or combining.
How to use CATV protector and notes.
Since a CATV protector is a surge arrester fundamentally, it is installed in the outdoors. Therefore, the waterproofing mechanism is equipped. It is made not to install indoors.
Since there are "streamed noise prevention type", "two-way communication type", "1 branch type", "2 distribution type", etc. in the kind of CATV protector, it is necessary to carry out usage which responded to the use.
It wires so that the terminal of input and output may not be mistaken. The thing with two output terminals wires so that the use may not be mistaken. Since the input and output side is generally insulated, it dissociates and the cable input-and output side wires. It is made not to bundle the input cable and output side together.
The CATV protector generally uses the messenger wire for the grounding. For the reason, a messenger wire is connected to the grounding terminal by the side of a protector.
You may attach a CATV protector to the antenna for ground digital broadcasting.
Although no surge arresters are also attached to the common antenna for ground digital reception (UHF antenna) in many cases, this CATV protector can also be used as a surge arrester of an antenna. In this case, it is necessary to perform grounding construction on the ground in the place of a protector. The ground resistance value in this case is 100ohms or less.