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Figure 3-4.-RT-889/APS-115 receiver-transmitter control panel | Up
Aviation Electronics Technician 1 (Organizational) | Next
Figure 3-6.-C-7557/ASA-69 radar scan converter control |
AS-2146/APS-115 Antenna
The radar antenna radiates the transmitter pulses
in either a pencil beam mode or a cosecant squared
(spoiled) beam mode. The mode of radiation is not
operator selectable.
A spoiler must be physically
added to the antenna dish if the spoiled beam
operation is required. This spoiler causes the beam to
be a wide vertical beam.
The basic characteristics of the antenna are as
follows:
Scan speed:
6 RPM with 2.5 microsecond
pulsewidth or 12 RPM with
0.5 microsecond pulsewidth
Radiation pattern: Pencil beam 2.5 by
3.8 degrees; spoiled beam
2.5 by 20 degrees
Scan modes:
45-degree sector, 360-degree
full scan, 240-degree sector
(single system operation)
Manual tilt:
+10 to –20 degrees
Tilt stabilization:
Pitch and roll ±30 degrees
A361 Antenna Elevation Parking Control
The antenna elevation parking control is used to
stow the aft antenna in a zero-degree elevation
attitude, relative to the aircraft, when the aft radar is in
the standby mode.
C-7512/APS-115 Radar Control Panel
There are two radar control panels (fig. 3-5), one
for the forward and one for the aft system. This
control panel enables the operator to turn the system
on and control most of the functions of each system.
There are 12 function switches and 2 fail lights on
each control box.
WARNING
Ensure power is applied to the RADAR
SCAN switch on the C324 TACCO control
panel prior to applying power to the
APS-115 radar system. If the RADAR
SCAN switch is left off and then turned on
after power is applied to the APS-115, the
system will automatically cycle to high
voltage on.
FREQ PUSH BUITON.— This push button has
two positions. With FIXED selected, the system will
be in the fixed frequency mode of operation. With
AGILE selected, the system will be operating in the
sweep frequency mode. This mode is used in high
clutter areas to improve target definition.
PULSE PUSH BUTTON.-— The operator uses
this button to select either LONG or SHORT
pulsewidths for the system. In the LONG mode, the
system has a 2.5 µsecond pulsewidth, 400 pps PRF,
and 6-RPM antenna scan rate. In the SHORT mode,
the system has a 0.5 µsecond pulsewidth, 1600 pps
PRF, and 12-RPM antenna scan rate.
HV PUSH BUTTON.— This is the high-voltage
select switch. There are three indications on the
switch, of which only two are selectable. As soon as
the system power is turned on, the WARMUP section
illuminates. This section will remain illuminated
until the system has warmed up. The operator cannot
apply high voltage until the system has warmed up
sufficiently. After approximately 3 minutes of
Figure 3-5.-C-7512/APS-115 radar control panel.
3-5
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