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B. PASSENGER AIRPLANES, The weather radar receiver/transmitters (R/T) are ARINC 600 size 8 MCU units. The R/T units are installed in a dual R/T mount located on electronic equipment center rack E5. Access to the R/T is gained through the right crawlway that extends forward of the main electronics equipment center.
C. FREIGHTER AIRPLANES, The weather radar receiver/transmitters (R/T) are ARINC 600 size 8 MCU units. The R/T units are installed in two single R/T mounts located on the centerline of the compartment floor in the nose cargo door section.
D. The double conversion superheterodyne receiver contains a limiter, a mixer, two IF amplifiers, an analog to digital converter, two digital filters, and an encoder. The digital filters optimize the bandpass of the receiver for improved signal-to-noise ratio. The encoder sends the digital output of the receiver thru the ARINC 453 line driver circuits to the indicators.
E. The front panel of the R/T has an overtemperature (OVERTEMP) fault indicator, a fault RESET button, an elapsed time indicator, and an Automatic Test Equipment (ATE) connector. The overtemperature fault indicator monitors the electronic cooling system and must be manually reset (Ref 21-58-00). The RESET button is used to manually reset the OVERTEMP fault indicator. The time indicator displays elapsed operating time in hours.
5. R/T Mount
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A. PASSENGER AIRPLANES; The R/T mount consists of a dual mounting shelf for the two R/Ts, mating quick-disconnect electrical and waveguide fittings, blower motors, blower motor test switches, a rotary waveguide switch and rf feeder waveguides between the switch and R/Ts. Two holddown clamps secure each R/T to the R/T mount.
B. FREIGHTER AIRPLANES; The R/T mount provides the rf waveguide interconnect between the R/T and the antenna and wiring connections between various system components. The two single R/T mounts are located below the floor compartment of the nose cargo door section.
EFFECTIVITY
AF 160, 162-171, 183, 184 CONFIG 4 01 Page 9 Sep 25/9434-43-00
6. Waveguide
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A. Flexible waveguide sections are installed between both R/T mounts to the waveguide switch. From the waveguide switch rigid sections extend forward and pass through the pressure seal into the nose radome area. In the unpressurized nose radome rigid sections are connected to a final flexible section that connects to a top-mounted waveguide flange on the antenna.
7. Waveguide Switch
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A. An rf waveguide switch 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.
B. PASSENGER AIRPLANES;
The waveguide switch is part of the R/T mount.
C. FREIGHTER AIRPLANES; The waveguide switch is mounted to an airplane floor compartment beam.
8. Antenna
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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 performs the functions of transmitting rf energy in a radiating pattern forward of the airplane and receiving the returning echo and sending this data to the selected receiver/transmitter.
C. The antenna consists of an antenna pedestal and 30 inch antenna flat plate radiator. In the pedestal two independent systems provide command signals to the scan and elevation stopper motors. Each system (system 1 and system 2) consists of a power supply, motor driver, receiver, receiver/monitor driver and zero monitor. The antenna flat plate radiator moves in both scan and elevation excursions to maintain a constant radar pattern over the full range of airplane manuvers.
D. On the antenna pedestal there are two toggle switches used to disable the scan and elevation stepper motors. Two connectors are provided for interface with the left and right R/T.
E. Operation of either system 1 or 2 TILT control, on the control panel either up or down from the zero position impresses a fixed angle on the stabilized/boresight zero position of the antenna flat plate radiator. Maximum compensating movement of the antenna is 30 degrees combined pitch and roll plus or minus the TILT angle set at the control panel.
9. Operation
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A. General
EFFECTIVITY
AF 160, 162-171, 183, 184 CONFIG 4 01 Page 10 Sep 25/9434-43-00
B. Weather radar operation consists of: C. Operational description,
D. Functional description, E. System monitoring, F. Self-test and
G. System shutdown procedures. The Operational description is a brief overall description of the weather radar system. The functional description, system monitoring, and self-test are more in-depth descriptions of the system components and their interface. The system shutdown procedures are performed if the weather radar system is put into operation in the operational description (Fig. 2 and 3).
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本文链接地址：747飞机维护手册AMM CHAPTER 34 - NAVIGATION 第34章导航3(103)
