12 inch antenna/8 degree beam width.
a. The following paragraphs describe the WXP-850A/B operating controls.
With the TWR-850 system, the colors of weather radar mode annunciators, arc format, and map
format depend on the type of MFD display being used. Refer to the Universal EFI-890R vendor s
manual for annunciator, arc format, and map format colors.
(1) MODE Control. The WXP MODE control is a rotary switch used to select the various operating modes
of the TWR-850 system. The modes and their operation are as follows (Refer to Figure 3-10):
(a) OFF mode on the WXP-850A/B removes power from the RTA-85X Receiver/Transmitter/Antenna.
OFF will be displayed on the MFD. OFF does not remove power from the WXP-850A/B control.
(b) STBY (Standby). In STBY mode, power is applied to the RTA-85X Receiver/Transmitter/Antenna with
a short (approximately 3-second) initialization period. During the initialization process, the RTA drives its antenna
to the bore sight position (0-degree azimuth and 0 degree tilt). The antenna will remain in this position as long as
STBY is selected. The Weather display, radar transmitter, and after initialization, antenna scan drive circuits, are
inhibited whenever STBY is selected. STBY is annunciated on the MFD
(c) TEST mode initiates the radar and display color self-test function and causes the self-test display
to appear. Any range can be selected for the self-test function. TEST is annunciated on the MFD. The transmitter
is disabled in the TEST mode, but antenna scan and tilt functions are enabled. This allows ground personnel to
visually inspect the antenna for proper scan and tilt operation without the concern of radiation hazard. The radar
self-test display is graphically described in Figure for the MFD. The display consists of six colored arcs evenly spaced
across the full sector of the display. Each arc veriies the system s ability to display the precipitation intensity level
or other display that is normally represented by that color. The display of the self-test function is as follows: at the
apex, occupying a range approximately equal to two of the color bands, are two arcs of black which represent no
detectable moisture. Progressing outward, the colored arcs precede as green, yellow, red, magenta, and a ring
that alternates between red and magenta, and inally, an outer band of yellow. The green band represents the irst
level of precipitation. The irst band of yellow represents the second level of precipitation intensity, while the outer