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TX RX Systems Inc. Manual 7-9352 (version 4) 01/27/04 Page 9

antenna or signal source and the output distri-

bution system does not exceed the signal

boosters gain by at least 15 dB. This condition

will reduce the effectiveness of the system and

may possibly damage the power amplifier

stages.

2) The major cause of damage to signal boosters

is the application of input RF power levels in

excess of the maximum safe input. This can

happen inadvertently when connecting a signal

generator with full power out to one of the inputs

or by a very strong signal that is far stronger

than expected. Following the pre-RF connection

checks listed next will help to avoid these two

problems.

PRE-RF CONNECTION TESTS

Certain characteristics of the signal distribution

system should be measured before connecting it to

the signal booster. This step is necessary to insure

that no conditions exist that could possibly damage

the signal booster and should not be skipped for

even the most thoroughly designed system. Two

characteristics need to be measured; antenna iso-

lation and input signal levels.

Test Equipment

The following equipment is required in order to per-

form the pre-installation measurements.

1) Signal generator for the frequencies of interest

capable of a 0 dBm output level. Modulation is

not necessary.

2) Spectrum analyzer that covers the frequencies

of interest and is capable of observing signal

levels down to -100 dBm.

3) Double shielded coaxial test cables made from

RG142 or RG55 coaxial cable.

Antenna Isolation

Antenna isolation is the signal path isolation

between the two sections of the signal distribution

system that are to be connected to the signal

boosters antenna ports. Lack of isolation between

the input and output antennas can cause the

amplifiers in the system to oscillate. This can hap-

INTERNAL

SIGNAL DISTRIBUTION

SYSTEM

SPECTRUM

ANALYZER

EXTERNAL

ANTENNA

SIGNAL

GENERATOR

ZERO LOSS

REFERENCE

ISOLATION (dB)

Figure 2

: Typical test equipment setup for measuring antenna isolation.