D. The R/T mount consists of a dual mounting shelf for the R/Ts, mating quick-disconnect electrical and waveguide fittings, a rotary waveguide switch, and rf feeder waveguides between the switch and R/Ts. Two holddown clamps secure the R/Ts to the R/T mount.
E. The R/T mount provides the rf waveguide interconnection between the receiver/transmitters and antenna and wiring connections between various system components. The R/T mount is located on equipment rack E5 in the right-hand crawlway outboard of the nose gear wheel.
5. Waveguide
_________
A. The waveguide connects the selected R/T from the waveguide switch to the antenna. A flexible waveguide section is connected to the waveguide switch and then rigid sections extend forward and pass through the pressure seal into the nose radome area. In the unpressurized nose radome the rigid waveguide sections connect to a flexible waveguide section. The flexible waveguide section is connected to a quick-disconnect flange on the antenna.
B. An rf waveguide switch on the R/T mount connects the two R/T unit waveguides to the antenna waveguide. The waveguide switch is controlled by the system transfer switch on the control panel.
6. Antenna
_______
EFFECTIVITY
AF 121, 122; SN 351-399 CONFIG 3 02 Page 7 Apr 25/9834-43-00
A. The antenna is mounted on the airplane bulkhead behind the radome in an unpressurized section of the airplane. It is used for both transmitting and receiving.
B. The antenna system consists of an azimuth drive motor, a tilt drive motor, an azimuth position synchro, an elevation position synchro, and a 30-inch planar array radiating element.
C. Operation of the TILT control, on the control panel, up or down from the zero position impresses a fixed angle on the stabilized/boresight zero position of the antenna planar array. Maximum compensating movement of the antenna is 30-degree combined pitch and roll plus or minus the tilt angle set at the control panel.
7. Operation_________
A. General
(1) Weather radar operation consists of: B. Normal Operation,
C. Functional Description, D. System Self-Test and E. System Shutdown Procedures. Normal operations describes normal startup operations of the weather radar system. The functional description is a more in depth description of the system components and their interface. The system shutdown procedures are performed when weather radar operations are completed.
WARNING: DO NOT OPERATE WEATHER RADAR WHILE THE AIRPLANE IS BEING
_______ REFUELED OR DEFUELED AND DO NOT OPERATE IN ANY RADIATION MODE WHILE A FUELING OPERATION IS BEING CONDUCTED WITHIN 300 FEET OF THE ANTENNA OR AN EXPLOSION MAY OCCUR.
PERSONNEL MUST NOT ENTER AN AREA CLOSER THAN 50 FEET OF A RADIATING ANTENNA OR INJURY TO PERSONNEL MAY OCCUR.
CAUTION: WHEN THE WEATHER RADAR IS OPERATED IN ANY MODE OTHER THAN
_______ TEST, DIRECT THE NOSE OF THE AIRPLANE SO THE FORWARD 180-DEGREE SECTOR IS FREE OF LARGE METALLIC OBJECTS (HANGARS, TRUCKS, OTHER AIRPLANES, ETC.) FOR A DISTANCE OF 300 FEET OR DAMAGE TO THE RECEIVER MAY OCCUR.
WHEN OPERATION IN A RADIATING MODE, ALL LARGE METALLIC OBJECTS MUST BE AT A DISTANCE OF 300 FEET OR GREATER BEFORE TILTING THE ANTENNA DOWN OR DAMAGE TO THE RECEIVER MAY OCCUR.
B. Normal Operation
(1)
Prior to operation perform the following:
(a)
Check WEATHER RADAR circuit breakers on P-7 panel are closed.
(b)
Check inertial navigation system INS-1 and INS-2 is in NAV (navigate) mode (Ref 34-41-00).
(2)
Position controls on weather radar indicator as follows:
(a)
Range switch - 60 or 80
(b)
BRT control - midscale
(c)
SN 351-399;
SCAN/HOLD switch - SCAN
EFFECTIVITY
AF 121, 122; SN 351-399 CONFIG 3 01 Page 8 Apr 25/9834-43-00
Weather Radar System Block Diagram
Figure 2
EFFECTIVITYAF 121,122;
CONFIG 3 SN 351-399
799 Page 9
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