Bird Technologies Group 5PI616550 Manual De Usuario

One set changes state when the AC power supply
shuts down for any reason and the unit switches to
operation on the backup DC power system.

The other set of contacts changes state when any
of a number of fault conditions arises within the
electronics such as current drain outside of the
expected operating range in some module.

A six-terminal strip is provided for the interface and
uses screw terminals for ease of connection. Route
the alarm wires through one of the access holes in
the bottom of the box, strip about 3/16” of insula-
tion from each end, loosen the screw terminal,
insert and retighten. Use #20 or #22 gauge insu-
lated wire.

Use of these terminals is optional. SB II also has a
number of status LEDs built-in to individual mod-
ules to indicate a fault condition.

RF Connections
N(F) bulkhead connectors are provided on the bot-
tom of the cabinet for connection to the signal dis-
tribution system. Be sure that the correct branch of
the distribution system is connected to its corre-
sponding Uplink/Downlink connector or the system
will not work properly. Using high-quality connec-
tors with gold center pins is advised. Flexible
jumper cables made of high-quality coax are also
acceptable for connecting to rigid cable sections.

Antenna isolation between the uplink and downlink
branches should be measured before connecting
the signal booster to the antenna system. 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.

Note: The 80 dB gain models are fac-
tory preset to 50 dB gain and should
only be reset to a higher value after
determining the safe maximum gain
based on antenna isolation

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 or better.

3) Double shielded coaxial test cables made from

RG142, RG55 or RG223 coaxial cable.

Antenna Isolation 
Just like the feedback squeal that can occur when
the microphone and speaker get too close to each
other in a public address system, a signal booster
can start to self oscillate. This can occur when the
isolation between the input antenna or signal
source and the output distribution system does not
exceed the signal boosters gain by at least 15 dB.
Oscillation will reduce the effectiveness of the sys-
tem and may possibly damage the power amplifier
stages.

In general, if one or both antenna ports are con-
nected to sections of radiating coaxial cable (lossy
cable) the isolation will be more than adequate
because of the high coupling loss values that are
encountered with this type of cable. When a net-
work of antennas are used for the input and output,
this problem is much more likely. Isolation values
are relatively easy to measure with a spectrum
analyzer  and signal generator.

Procedure for Measuring Antenna Isolation
1) Set the signal generator for a 0 dBm output

level at the center frequency of the signal boost-
ers passbands.

2) Set the spectrum analyzer for the same center

frequency and a sweep width equal to or just
slightly greater than the passband chosen in
step one.

3) Connect the test leads of the signal generator

and the spectrum analyzer together using a
female barrel connector, see Figure 4. Observe
the signal on the analyzer and adjust the input
attenuator of the spectrum analyzer for a signal
level that just reaches the 0 dBm level at the top
of the graticule. 

NOTE