TM 11-5895-846-14
Figure 6-5. Antenna Mounted Electronics
(a) Low-noise amplifiers. The low-noise
and amplifier test circuits. AC power is supplied from the
LNA control unit located in the LNA control/translator.
amplifiers (LNA) are SHF preamplifiers which provide
The unit is maintained at a constant temperature of + 75
sufficient gain to meet the receive system noise
C by a dual heater system. A 130-watt, thermostatically-
temperature requirements and adequate input to the
controlled heater is on whenever the LNA is operating.
downconverters in the shelter. Each LNA is contained in
Under low temperature conditions, an additional 300-watt
a weatherproof, temperature-controlled case mounted at
element can be used to bring the LNA to operating
the rear of the antenna center section. The LNA
temperature more quickly.
Each LNA has a
contains a parametric amplifier to assure stable
corresponding LNA control panel in the LNA
operation, a bandpass filter, and an isolator. Each LNA
control/translator.
also contains dc power supply, fault detection circuits,
6-9
