(e)  
An ON/OFF 2 discrete ground from the SYS transfer switch in the 2 position goes to the R/T No. 2 switch S1. This ground energizes R/T No. 2 relay K1 as discussed for R/T No. 1 above. With the SYS transfer switch in the 2 position an additional ground is sent to disable R/T No. 2.

 EFFECTIVITY

 AF 160, 162-171, 183, 184  CONFIG 4  01 Page 21  Sep 25/9434-43-00
 (f)  
Energizing R/T No. 1 or No. 2 relay K1 sends 115-volt ac switched power to the respective cooling blower located on the R/T mount. A blower test switch on each R/T mount tests blower operation when the R/T is removed.

 (g)  
Power to the captain's and first officer's indicator comes directly from the 115 volt ac circuit breaker on the P7 circuit breaker panel.

 (10)
 Weather Radar System Control Functions

 (a)  
The receiver/transmitter acquires ARINC 429 digital data from the weather radar control panel and indicators and inertial navigation units No. 1 and 2.

 (b)  
AF 160, 162-171; Either indicator PWR switch provides the discrete ground to turn on the radar system selected by the weather radar control panel SYS transfer switch. One of the two indicators can be turned off with its PWR power switch placed in off without turning off the system selected by the control panel.

 (c)  
The weather radar control panel system 1 and 2 logic circuits accepts data from their respective control panel mode switches, and gain and tilt controls. The system 1 and 2 logic circuits output ARINC 429 serial data on two control bus 0 to R/T 1 and R/T 2 respectively. Range ARINC 429 serial data from the captains indicator is sent to R/T No. 1 and No. 2 on control bus 1. Range serial data from the F/Os indicator is sent to R/T No. 1 and No. 2 on control bus 2.

 (d)  
The control word is sent to the selected R/T. The control information required by the R/T is assembled by the microcomputer as it examines the control words. The serial data is multiplexed, converted to parallel data and routed to the I/O ports of the R/T units.

 (e)  
Within the receiver/transmitter, the input control data is fed to the timing, control, and monitoring circuts and the antenna stabilization circuits. The timing, control, and monitoring circuits provide timing, control, and monitoring of all functions of the receiver/transmitter.

 (f)  
ARINC 453 data buses 1 in bipolar manchester format are sent from R/T 1 and R/T 2 to the captain's indicator. Also ARINC 453 data buses 2 in bipolar manchester format are sent from R/T 1 and R/T 2 to the F/Os indicator.

 (11)
 Control Panel Function

 (a)  
The control panel is a microprocessor-controlled unit which provides mode, system gain, ground clutter suppression and antenna tilt control information for operation to the selected R/T.

 (b)  
When system 1 is selected by the control panel, the 28-volt dc switched power from R/T 1 is sent back to the control panel system 1 (left) power supply. The powered system 1 or system 2 power supply provides operating power to system 1 or system 2 logic circuits.

 EFFECTIVITY

 AF 160, 162-171, 183, 184  CONFIG 4  01 Page 22  Sep 25/9434-43-00
 (c)  
The logic circuits converts the control panel switch inputs into ARINC 429 data words. All inputs are sent directly to the digital input ports except the antenna input. The dual mode and gain switch inputs are applied to input latches. Antenna tilt analog signals are changed to digital signals and sent to the input port. The logic circuits with the microcomputer determine the ARINC word format and the shift register change the parallel data into serial word format. The ARINC transmitters produce the ARINC 429 control word 0 to R/T No. 1 and R/T No. 2.

 (d)  
The system 2 logic circuits operate identically to system 1 when the SYS transfer switch is in the SYS 2 position.

 (e) Mode select switch operations are explained as follows: 1) TEST mode - activates the test mode for the selected system. Initially, the transmitter is enabled for less than 1 second and then muted for the remainder of the test. A test pattern is generated containing four concentric arcs with magenta, red, yellow, and green display from top to bottom. An antenna test sequence is automatically performed. A complete left-to-right scan and up-to-down tilt cycle will occur, with the tilt angle displayed on the indicator. 2) WX mode - places weather radar system in the normal weather detection mode of operation. The indicator shows areas of significant rainfall as colored areas for ranges from 10 to 320 miles or 20 to 240 miles. Terrain may also be displayed. 3) MAP mode - terrain features below and forward of the airplane are displayed when the control panel TILT control is placed in a down attitude. The most reflective returns are displayed in yellow and lower level returns are displayed in green. The system gain is selectable in the MAP mode by the use of the GAIN control on the weather radar control panel. 4) AF 160, 162-171; WX+T mode - selects the normal weather detection and turbulence modes of operation which show areas of significant rainfall and areas where rainfall and winds combine to produce turbulence returns within 50 miles of the airplane.
　
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