Weather Radar System Component Location 5D8
34-41-0 Figure 1 (Sheet 1) Jun 20/84
Page 2
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
5B8 Weather Radar System Component Location
Feb 20/85 Figure 1 (Sheet 2) 34-41-0
Page 3
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
Weather Radar System Component Location 5D8
34-41-0 Figure 1 (Sheet 3) Jun 20/84
Page 4
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
F. The indicator uses digital circuits, integration/averaging, and memory storage to provide a low noise non-fading display. The digital display is refreshed at a 60.7 Hz frame rate by video information stored in memory. The solid state memory holds the image between sweeps, with the data sweep displayed on the CRT moving in synchronism with the antenna's scan.
3. Receiver/Transmitter
A. The Weather Radar R/T unit transmits RF energy and receives the return signals to develop weather and terrain video outputs.
B. The Receiver Transmitter (R/T) is housed in a short 1/2 ATR case. A blower is mounted on the front of the unit to provide cooling air. Behind the access panel marked GAIN ADJ (Fig. 1) are two potentiometers for calibrating the system pitch and roll stabilization circuits to the output of the airplane attitude reference system. A single connector at the rear of the unit provides electrical connections between the R/T and other units. A quick disconnect waveguide fitting provides interconnection between the R/T and the waveguide system. Under the dust cover is a MOD ON PUSH/MOD OFF PULL switch to disable the R/T modulator transmit circuit.
C. The R/T unit operates at a frequency of 9345 + 30 MHz (X band). The peak power output is 10 kw; the average power output is 3 watts. The pulse repetition frequency is 120 pps.
4. Waveguide
A. The waveguide is standard rectangular section X-band and consists of rigid and flexible sections which connect the receiver-transmitter to the antenna or dummy load via a rotating waveguide switch.
5. Dummy Load
A. A dummy load is provided at the rotary waveguide switch mounted near the R/T unit. When TEST mode is selected on the RANGE switch, the waveguide switch rotates to direct output of the R/T into the dummy load for dissipation. When an operating mode (WX, CYC, or MAP) is selected and the RANGE switch is set to an NM range, the waveguide switch rotates to direct output of the R/T to the antenna.
6. Antenna
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.
5D8
Jun 20/84 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 34-41-0 Page 5
B. The antenna is a single-axis stabilized unit consisting of a pedestal containing the necessary positioning mechanisms and circuitry, and a slotted 24-inch flat circular plate radiator. The antenna emits a 4.2° pencil beam in all modes. It is capable of scanning angles of 40° or 80° either side of dead ahead (80 or 160 total degrees). The antenna has a total of 40 +3 degrees of pitch and roll movement to compensate for airplane attitude changes. The scan rate is 14 looks/minute on the 160 degree scan and 28 looks/minute on the 80 degree scan. The antenna assembly includes fixed sections and two rotating joints of X band waveguide.
C. An Azimuth Index Scale (Fig. 1), on the upper azimuth bearing, is indented at increments of
D. -80, -48.6, 0, +48.6, and +80 degrees. The index mark should be opposite +48.6 mark at the end of a 40 degree sweep, and opposite +80 at the end of 80 degree sweep. An Elevation Index scale is on the right side of the tilt bearing, and is indented at increments of 0, 15, 19.7, 20 and 30 degrees. The index is opposite the 15 degree mark when 15 degrees of manual tilt is selected. The Azimuth SCAN DISABLE switch is located on the left side of the antenna, and has a locking bar to hold the switch in the ON position.
7. Operation
A. General
(1) Weather radar operation consists of, A. Operational description and, B. Functional description. The Operational description is a brief overall description of the Weather Radar System. The Functional description is a more in depth description of the system components and their interface.
WARNING: DO NOT OPERATE WEATHER RADAR WHILE AIRPLANE IS BEING REFUELED OR DEFUELED AND DO NOT OPERATE IN ANY RADIATING MODE WHILE A FUELING OPERATION IS BEING CONDUCTED WITHIN 200 FEET OF THE ANTENNA OR AN EXPLOSION MAY OCCUR.
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