Honeywell PRIMUS 660 Pilot's Manual page 40

In GMAP mode, variable gain is used to reduce the level of strong
returns from ground targets.
Minimum gain is attained with the control at its full ccw position. Gain
increases as the control is rotated in a cw direction from full ccw at full
cw position, the gain is at maximum.
The VAR legend annunciates variable gain. Selecting RCT or TGT
forces the system into calibrated gain.
NOTE: Some controllers have a preset position on the rotary knob.
Rotating the knob to PRESET provides calibrated gain
functions. Rotating the knob out of the PRESET position
allows variable gain operation.
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REV 2
R
PRIMUS 660 Digital Weather Radar System
Operating Controls
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