TM 11-5895-846-14
(3) Control, fault detection and isolation. The
line path through the directional coupler, wideband
POWER circuit breaker on the right side of the panel
preselector, wave-guide switch, LNA-1, the coaxial
controls the power supply. Power to the LNA is directly
switch in the LNA BITE assembly, and out to the
controlled by the LNA control POWER circuit breakers.
received power divider in the shelter.
The input
Translator operation is initiated by the TRANSLATOR
directional coupler permits the coupling of a test signal
switch. POWER supply voltages and the 725-MHz
into the receive path. It isolates the test signal input from
source output and phase are checked by the MONITOR
the receive path by 20 dB. Test signals are sent from
meter and switch group. The translator should be used
the test translator located inside the shelter and are used
only when the terminal is not performing any of its
when performing a loop test of the entire
operational functions. The upconverter must be tuned
communications channel. When no testing is required,
725 MHz above the downconverter for this test. To avoid
the unit can be turned off. The off-line LNA, in this case
interference through the satellite, this system loop test
LNA-2, is connected into the LNA BITE assembly
should be done with the PA output connected to a
through the remaining ports of the waveguide and
dummy RF load.
(4) LNA BITE. The LNA BITE assembly is
coaxial switches. When energized by a TEST switch on
the LNA control/translator panel, the LNA BITE assembly
used for switching the output of either LNA to the
generates an SHF test signal. This signal is routed
receiving equipment in the shelter. A second function of
through the standby LNA and reenters the LNA BITE
the unit is to generate a test signal to test the off-line
assembly where it is detected. If the gain of the LNA is
(standby) LNA.
The directional coupler (fig. 6-18)
at least 37 dB, the detected output will illuminate an LNA
connects to a test translator. By a simple 725-MHz
NORMAL test lamp on the LNA control/translator panel.
downshift of the output of the power amplifier (sampled
Refer to figure 6-18. This test can be performed at any
from the output waveguide) and the coupling of the result
time on either LNA when it is off-line and has been
to the receive channel at the proper level, the test
energized for at least five minutes.
translator enables a complete loop test of the
communications channel. The RF components mounted
6-32
