Section IV. TRANSPONDER AND RADAR
3-30. WEATHER RADAR SET (AN/APN-21 5).
Description. The weather radar set (fig.326),
provides a visual presentation of the general sky area of
approximately 120° around the nose of the aircraft, extending
to a distance of 240 nautical miles. The presentation on the
screen shows the location of potentially dangerous areas, such
as thunderstorms and hailstorms, in terms of distance and
azimuth with respect to the aircraft. The radar is also capable
of ground mapping operations. The weather radar set is
protected by a 5-ampere RADAR circuit breaker located on
the overhead circuit breaker panel (fig. 2-27).
Controls/Indicators and Functions.
GAIN control. Used to adjust radar receiver
gain in the MAP mode only.
STAB OFF switch. Push type on/off switch.
Used to control antenna stabilization signals.
Range switches. Momentary action type
switches. When pressed, clears the screen and increases or
decreases the range depending on switch pressed.
TILT control. Varies the elevation angle of
radar antenna a maximum of 15 degrees up or down from
horizontal attitude of aircraft.
60° switch. Push type on/off switch. When
activated, reduces antenna scan from 120° to 60 degrees.
TRACK switches. Momentary action type
switches. When activated, a yellow track line extending from
the apex of the display through top range mark appears and
moves either left or right, depending on the switch pressed.
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