Bird Technologies Group 5PI613805 Manual De Usuario
61-38-05 UserMan page 16 of 38
TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 16
and downlink branches are physically identical,
both being constructed from the same set of sub-
assemblies, the signal flow discussion that follows
is applicable equally well to both branches. The
only difference between the two branches is the
tuning of their passbands.
both being constructed from the same set of sub-
assemblies, the signal flow discussion that follows
is applicable equally well to both branches. The
only difference between the two branches is the
tuning of their passbands.
Signals enter the system through the RF connec-
tors at the top of the cabinet. This is where the cus-
tomers antenna system is interfaced to the booster.
Input signals are immediately passed through pas-
sive filtering. The filter configurations can vary
slightly depending on the exact model of booster.
The filters provide the necessary isolation to allow
a pair of amplifier chains to be tied together provid-
ing bi-directional amplification with a single com-
mon input and common output connection. A
secondary but very beneficial effect of filtering is
instantaneous input and output frequency spec-
trum limiting which helps to prevent amplification of
unwanted channels. After filtering signals are then
applied to a preamplifier stage (the first section of
the multi-stage amplifier assembly 3-11423).
tors at the top of the cabinet. This is where the cus-
tomers antenna system is interfaced to the booster.
Input signals are immediately passed through pas-
sive filtering. The filter configurations can vary
slightly depending on the exact model of booster.
The filters provide the necessary isolation to allow
a pair of amplifier chains to be tied together provid-
ing bi-directional amplification with a single com-
mon input and common output connection. A
secondary but very beneficial effect of filtering is
instantaneous input and output frequency spec-
trum limiting which helps to prevent amplification of
unwanted channels. After filtering signals are then
applied to a preamplifier stage (the first section of
the multi-stage amplifier assembly 3-11423).
Following the preamplifier signals are applied to
the input of OLC (output level control) assembly 3-
6280. This assembly will attenuate the incoming
signals if necessary, to protect the final amplifier
from being overdriven by stronger than usual input
signals. The amount of attenuation is determined
by a reference voltage produced by a detector cir-
cuit built into the OLC assembly, which continu-
ously samples the output level of the final amplifier.
Once past the OLC assembly the signals are
applied to a driver amplifier composed of the final
three sections of the multi-stage amplifier assem-
bly 3-11423. The driver amplifier ensures that sig-
nals applied to the next stage, the final amplifier,
are at their optimum level and as free of any inter-
modulation distortions as possible. The high power
amplifier 3-11792 is a linear amp operated at con-
siderably less than it’s maximum output power to
insure maximum linearity.
the input of OLC (output level control) assembly 3-
6280. This assembly will attenuate the incoming
signals if necessary, to protect the final amplifier
from being overdriven by stronger than usual input
signals. The amount of attenuation is determined
by a reference voltage produced by a detector cir-
cuit built into the OLC assembly, which continu-
ously samples the output level of the final amplifier.
Once past the OLC assembly the signals are
applied to a driver amplifier composed of the final
three sections of the multi-stage amplifier assem-
bly 3-11423. The driver amplifier ensures that sig-
nals applied to the next stage, the final amplifier,
are at their optimum level and as free of any inter-
modulation distortions as possible. The high power
amplifier 3-11792 is a linear amp operated at con-
siderably less than it’s maximum output power to
insure maximum linearity.
Signals output from the high power amplifier stage
are routed to the detector input of the OLC assem-
bly by the first signal sampler 3-6999. The purpose
of the detected signal is to adjust the amount of
attenuation provided by the OLC assembly to the
incoming signal after the preamplifier stage. The
output of the high power amplifier is passed
through a second signal sampler 3-5969 that pro-
vides a -50 dB sampled signal as a convenience for
service technicians. The signals then pass through
are routed to the detector input of the OLC assem-
bly by the first signal sampler 3-6999. The purpose
of the detected signal is to adjust the amount of
attenuation provided by the OLC assembly to the
incoming signal after the preamplifier stage. The
output of the high power amplifier is passed
through a second signal sampler 3-5969 that pro-
vides a -50 dB sampled signal as a convenience for
service technicians. The signals then pass through
passive filtering before leaving the signal booster at
the output connector located on the top of the cabi-
net. This is where the customers antenna system is
interfaced to the booster.
the output connector located on the top of the cabi-
net. This is where the customers antenna system is
interfaced to the booster.
SYSTEM COMPONENTS
Each of the major system components used in the
model 61-38-05 family of signal boosters are briefly
discussed in the following text. Refer to the system
specification drawing that shipped with your system
during this discussion. The specification drawing
will include complete electrical and mechanical
specifications for your model. These include fre-
quency band, bandwidth, power gain and maxi-
mum power ratings. Recommended maximum
power ratings are shown for single signal and multi-
ple signal applications.
model 61-38-05 family of signal boosters are briefly
discussed in the following text. Refer to the system
specification drawing that shipped with your system
during this discussion. The specification drawing
will include complete electrical and mechanical
specifications for your model. These include fre-
quency band, bandwidth, power gain and maxi-
mum power ratings. Recommended maximum
power ratings are shown for single signal and multi-
ple signal applications.
The functional block diagram included on the spec-
ification drawing shows all of the major subassem-
blies and their interconnections. Part numbers for
the major assemblies are also shown. We suggest
you look this drawing over carefully to fully familiar-
ize yourself with the unit.
ification drawing shows all of the major subassem-
blies and their interconnections. Part numbers for
the major assemblies are also shown. We suggest
you look this drawing over carefully to fully familiar-
ize yourself with the unit.
Passive Filtering
The passive filters on the input and output ends of
each active section have one major purpose: they
provide the necessary isolation to allow a pair of
amplifier chains to be tied together providing bi-
directional amplification with a single common
input and common output connection. The filters
provide duplex operation and each one is tuned to
pass either the downlink or uplink frequency band.
They must provide a minimum isolation factor that
exceeds the amplifier gain by 15 dB in order to pre-
vent regenerative feedback and maintain spurious-
free operation. In the VHF spectrum, these filters
are usually constructed from cascaded coaxial
bandpass cavities or multistage helical bandpass
filters. Bandpass filters may be augmented by
notch filters using the same basic resonator style
(coaxial or helical). Notching filters allow the filter
response to be closely tailored to the specific isola-
tion requirements for the specific uplink and down-
link frequency band separation. Typical VHF
frequency pairs (repeater input/output frequencies
= Down/uplink frequencies) vary considerably in
frequency separation making flexibility in tailoring
the filter response a necessity for proper operation.
When necessary, single channel bandpass filters
may also be used as an augment to facilitate close-
spaced frequency operation without interference.
The passive filters on the input and output ends of
each active section have one major purpose: they
provide the necessary isolation to allow a pair of
amplifier chains to be tied together providing bi-
directional amplification with a single common
input and common output connection. The filters
provide duplex operation and each one is tuned to
pass either the downlink or uplink frequency band.
They must provide a minimum isolation factor that
exceeds the amplifier gain by 15 dB in order to pre-
vent regenerative feedback and maintain spurious-
free operation. In the VHF spectrum, these filters
are usually constructed from cascaded coaxial
bandpass cavities or multistage helical bandpass
filters. Bandpass filters may be augmented by
notch filters using the same basic resonator style
(coaxial or helical). Notching filters allow the filter
response to be closely tailored to the specific isola-
tion requirements for the specific uplink and down-
link frequency band separation. Typical VHF
frequency pairs (repeater input/output frequencies
= Down/uplink frequencies) vary considerably in
frequency separation making flexibility in tailoring
the filter response a necessity for proper operation.
When necessary, single channel bandpass filters
may also be used as an augment to facilitate close-
spaced frequency operation without interference.