SCAN
BRT
50 150
25 300 HOLD
BRT OFF
PPI-1N INDICATOR 5 PPI-1N INDICATOR 6
B
3 AZ 201-224 (50,150,300 NM RANGE SELECTION)
4 AF 157,161
5 AT ALL
6 IB 406-499; AZ 231-280; LH ALL
Weather Radar System Component LocationFigure 1 (Sheet 2)
EFFECTIVITY
CONFIG 1AT ALL; AZ ALL; LH ALL; 7XA Page 3AF 157,161; IB 406-499 Sep 25/94
34-43-00
..... ................ .............XA
5 10
CONTROL PANEL
PPI-1T INDICATOR
CONTROL PANEL
RADAROFF NORM
1
2
GAINSTBY CONT 5 10
UP
AUTOTEST MAP
05 DN
5 10
CONTROL PANEL
STBY
OFF
AZ 225-229,281-299
AZ 201-224
AT ALL
IB 406-499; AZ ALL EXCEPT
201-224; LH ALL
AF 157,161
Weather Radar System Component Location
Figure 1 (Sheet 3)
EFFECTIVITY
CONFIG 1AT ALL; AZ ALL; LH ALL;
7XA Page 4 AF 157,161; IB 406-499 Sep 25/94
34-43-00
115V AC
Weather Radar System Block Diagram
Figure 2
EFFECTIVITY AT ALL; AZ ALL; LH ALL;
CONFIG 1 AF 157,161; IB 406-499799 Page 5
34-43-00
Sep 25/94
E. The weather radar system has two types of self-test provisions; on-line monitoring for automatic fault indication, and operator-actuated test for further fault identification (and/or adjustment of the display). The on-line monitoring consists of antenna, R/T and VSWR fault lights/ annunciators at the R/T. R/T and ANT fault lights (if provided on the pilots' weather radar control panel) also perform on-line monitoring. The operator-actuated test causes the injection of test signals, which are used to generate a test pattern on the indicator, allowing the operator to adjust the display prior to flight.
F. The interface with other systems is shown in figure 2, in which the INS is shown providing antenna stabilizing signals.
2. Control Panel
_____________
A. On AZ ALL; LH ALL; IB 406-499, the control panel has illuminating pushbutton switches to allow mode selection. The buttons are mechanically interlocked such that only the last pushbutton pressed has effect on mode selection.
B. AT ALL, AF 157, 161, the control panel has a mode function selector switch to allow mode selection.
C. A radar system transfer switch allows selection of system (R/T) 1 or 2. A tilt control, calibrated in 1-degree increments, allows the antenna system to be tilted up or down through 15 degrees (in each direction).
XA AT ALL; AF 157, 161, receiver sensitivity in the map mode is controlled by a gain control potentiometer.
XA On AZ ALL; IB 406-499; LH ALL, receiver sensitivity in the radiate modes is controlled by a gain control potentiometer.
3. Receiver/Transmitter
____________________
A. LH ALL EXCEPT LH 082-099; AZ ALL EXCEPT 281-299; IB 406-499; AT ALL, the two weather radar receiver/transmitters (R/T) are full ATR size. Access to an R/T is gained through the right crawlway that extends forward from the main electronics equipment center. The R/T units are installed in a mount which has quick-disconnect waveguide fittings, a waveguide switch, and a dummy load.
LH 082-099; AZ 281-299; AF 157, 161;
access to the R/T's is gained through the access door, on the centerline,
on the compartment floor in the nose cargo door section.
B. Each R/T unit has a blower fan. Three fault monitor lamps and a reset button on the front panel of each R/T assist in isolating faults during maintenance testing. The front panel also mounts three gain adjustments, an air filter and an hours meter.
C. The R/T contains modulator, duplexer, receiver, stabilization, power supply, and control circuits. The modulator is solid-state, using silicon-controlled rectifiers (SCR's) and saturable reactors to perform the switching functions. Additional circuits protect all solid-state devices against such faults as magnetron arcing, short circuiting, open circuiting, SCR lock-on, and loss of trigger.
EFFECTIVITY
AT ALL; AZ ALL; LH ALL; CONFIG 1 AF 157, 161; ATG Page 6 IB406 THRU 499 Sep 25/94
34-43-00
D. To isolate the receiver from high power transmitted rf, a ferrite duplexer is employed. High energy pulses from a nearby radar set can not damage the receiver due to the action of the duplexer and a TR tube in the rf limiter.
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