TM 11-5895-846-14
a. Disconnect the SHF OUTPUT type N
WARNING
connector.
ELECTROMAGNETIC RADIATION
b. Loosen the six socket-head captive screws
DO NOT STAND IN THE DIRECT PATH
around the RF input waveguide. The screws are fully
OF THE ANTENNA WHEN THE POWER
loosened when the heads are extended under spring
IS ONI DO NOT WORK ON THE WAVE-
pressure.
GUIDES WHILE THE POWER IS ONI
c. Disconnect the power connector.
High
Frequency
electromagnetic
d. Hold the LN in place and loosen the four
captive screws which secure the LNA to the center
If you feel the slightest warming effect
while near this equipment, MOVE AWAY
e. Remove the LNA, taking care not to damage
QUICKLY!
the input waveguide.
f.
Remove the three sunshields and their standoff
CAUTION
supports from the faulty LNA, noting their positions.
The LNA is mounted on the center
g. Install the standoff supports and the three
section of the antenna. Use extreme
sunshields on the replacement LNA in the same
care during this procedure to avoid
positions as on the faulty LNA.
damage to the LNA and the other
h. Install the replacement LNA by performing
mounted electronic units.
The LNA
steps a through e in reverse order.
weights approximately 13 pounds.
NOTE
When waveguide flanges are opened to expose
the interior of the waveguides, it is very important to
enters the waveguides.
Section XV. MAINTENANCE OF LNA BITE
5-52.
Scope
NO. 2 position, then LNA 2 is connected (on-line)
This section contains instructions for the operational
between the antenna and the downconverter and LNA 1
checkout and adjustment of the LNA BITE and for
is connected (in standby) to the LNA BITE for test.
removal and replacement. The LNA BITE also includes
a coaxial transfer switch to provide LNA output switching.
5-54.
If this switch fails, the LNA BITE must be replaced and
then returned to the next higher level of maintenance.
WARNING
ELECTROMAGNETIC RADIATION
5-53.
Operation
DO NOT STAND IN THE DIRECT PATH
OF THE ANTENNA WHEN THE POWER
a. The LNA BITE receives power from, and is
IS ONI DO NOT WORK ON THE WAVE-
controlled by, the LNA control/translator. It also serves
GUIDES WHILE THE POWER IS ONI
as an interface between the LNA control/ translator and
High
electromagnetic
the waveguide switch. When the ON LINE switch on the
LNA control/translator is placed to the LNA NO. 1
If you feel the slightest warming effect
position, the control signal passes through the LNA BITE
while near this equipment, MOVE AWAY
to the LNA waveguide switch, which connects the
QUICKLY!
antenna to the input of (on-line) LNA 1.
b. The LNA waveguide switch also connects the
The LNA BITE should be adjusted whenever the Gunn
LNA BITE test output cable to the input of (standby) LNA
oscillator in the LNA BITE is tuned to a different
2. An auxiliary set of contacts in the LNA waveguide
frequency. Whenever the standby LNA test shows a
switch provides for the ON LINE indicator on the LNA
fault on both LNAs, the LNA BITE adjustment should be
control/translator and also for the coaxial transfer switch
checked and the LNAs retested, in standby, to help
in the LNA BITE. The coaxial transfer switch connects
determine if the LNA BITE is faulty before replacing the
the output of (on-line) LNA 1 to the downconverter inputs
LNA.
and the output of (standby) LNA 2 into the LNA BITE for
testing. When the ON LINE switch is placed to the LNA
5-74