Listen LR-100 Series, Руководство пользователя

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Speci
fi cations
Speci
fi cations
Programming
The antenna for the LR-100 can be mounted directly on the unit if desired. However, you may
find that the unit will provide better performance when the antenna is located elsewhere. If
you plan to mount the antenna in a different location than on the top of the unit, you must use
cable and connectors rated at 50 ohms. Although cable used for cable TV installations looks
similar to this cable, it won’t work with your Listen system.
If you need to run cable over a greater length than 50 feet for 216 MHz applications or greater
than 100 feet for 72 MHz applications, we recommend that you use RG-8 cable rather than
RG-58. It is a lower loss cable, meaning that more of your signal will reach the antenna.
Long cable runs can result in signal degradation due to “loss” characteristics of the cable. At 72
MHz, there is an average loss of 2 dB per 100 feet of cable and at 216 MHz an average* loss of
5 dB per 100 feet of cable. (A 3 dB loss means half of your power has been lost.) However, it is
better to suffer coaxial power loss than to try to shoot your signal through obstacles! Obstacles,
especially metal, can create drop-outs or reflections of your signal that will result in poor listening
conditions.
*Note: There are large varieties of 50 ohm, RG-58 and RG-8 cables. You may purchase a
cable that is better or worse than this value. Please check with the cable vendor or
manufacturer for exact specifications.
Coaxial Cable