C.  The indicator also contains circuitry for generating alphanumerics used to display information on the CRT (Fig. 3). The different types of indications are as follows:
(1)  
Message slot 1 - Mode presentation appears on top left corner of display. Selected mode is displayed as WX, WX+T, MAP, and TEST.

(2)  
Message slot 2 - Located at the top center of the display, annunciates, in flashing yellow characters, the alert messages of HOLD, WEAK or FAIL. If the data bus input to the indicator is not detected the FAIL message will be a flashing (blue) cyan color.

(3)  
Message slot 3 - Located at the top right corner of the CRT displays the selected range setting in blue (cyan) color.

(4)  
Message slot 4 - Located immediately below the MODE presentation, a color bar displayed. This message slot normally displays a green, yellow, and red color bar. Should the display experience a failure affecting the color scheme, the message slot will identify the modified color scheme.

(5)  
Message slot 5 - located directly below message slot 3 (range), indicates range mark intervals.

(6)  
Message slot 6, 7, 8, and 9 - located directly below message slot 4 (color bars), display system detected LRU faults. The yellow colored failure messages consists of T/R (receiver

- transmitter), ANT (antenna), and DSP (display indicator). The faults are priority rated with the highest priority displayed in slot 6 with descending priority in slots 7, 8 and 9. If the data bus input to the indicator is not deleted, combined FAIL T/R blue (cyan) messages in  slot 2 and 6 respectively will be displayed.

(7)  
Message slot 10 - The system GAIN setting is displayed at the bottom left corner of indicator's CRT in the MAP mode. Gain characters are in blue (cyan): MAX, 01 thru 08, MIN. Each gain step reduces system sensitivity by 2 dB.

(8)  
Message slot 11 - Located immediately to the right of message slot 10 at the bottom left corner of the indicator's CRT displays IDNT when ground clutter suppression is selected. Otherwise, the message is blank.

(9)  
Message slot 13 - The system stabilization status is presented at the bottom of the display, immediately to the left of the tilt message (slot 14). The message is normally blank for stabilized operation. A USTB message is displayed for a manually selected unstabilized condition. A flashing ATT message is displayed when an attitude input failure is detected. A SAT message is displayed when the system stabilization reaches saturated limits due to unusual attitude maneuvers. All messages are blue (cyan) colored.

(10)
Message slot 14 - Located at the bottom right corner of the indicator's CRT, displays the antenna tilt angle in 0.25-degree increments, from -15.00 to +15.00 degrees in blue (cyan). If the antenna tilt position is different than the position annunciated, a flashing yellow FAIL message in slot 2 and a yellow ANT failure message in slot 6, 7, 8 or 9 will be present.

505 
34-41-02 Page 6  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  Jun 20/86 

505  Weather Radar Indicator Controls and Numerics Location 
Jun 20/86  Figure 3 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  34-41-02 Page 7 

5.  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.
B.  The antenna is a line-of-sight type mount, having its elevation axis mounted on the scan axis. The radiator plate moves in both scan and elevator excursions to maintain a constant radar pattern over the full range of airplane maneuvers.
C.  On the antenna pedestal there are two toggle switches used to disable the scan and elevation stepper motors.
505 
34-41-02 Page 8  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  Jun 20/86 

K83165
505 Weather Radar Interface SchematicOct 20/84 Figure 4 34-41-02 Page 9/10BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.

6.  Operation
A.  Functional Description, Reception, Transmission, and Display (Fig. 4)
(1)  
The source of the RF transmission is in the R/T unit driver, where a 777.77 MHz signal is generated and applied to the power amplifier. In the power amplifier, the signal is amplified and split into two separate signals. The multiplier frequency multiplies the signals from the power amplifier in two stages and recombines them to obtain the 125 watt 9333.24 transmitter output signal.

(2)  
The duplexer couples the transmitter output signal to the waveguide. The duplexer is monitored by power monitor circuits that develop a loop error signal to correct for output frequency variation and noise. The output signal is transmitted through the waveguide and then radiated out the flat plate antenna.
　
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