Honeywell SPZ-8000 Pilot's Manual page 269

10 GAIN knob
The GAIN knob is a rotary control and push/pull switch that controls the
receiver gain. Push the GAIN knob in to put the system into preset
(calibrated) gain mode. Preset gain is the normal mode of operation and
is recommended for weather avoidance. In preset gain, turning the
GAIN knob does nothing.
Pull the GAIN knob out to put the system into the variable (VAR) gain
mode. Variable gain is useful for additional weather analysis. In the
weather mode, variable gain can increase receiver sensitivity over the
calibrated level to show very weak targets or it can be reduced below
the calibrated level to eliminate weak returns.
Selecting RCT, TGT, TRB, or GCR overrides the variable gain selection
and puts the system into the preset gain mode.
HAZARDOUS TARGETS ARE ELIMINATED FROM THE DISPLAY
WITH LOW SETTINGS OF VARIABLE GAIN.
In the ground mapping mode, variable gain is used to reduce the level
of strong returns from ground targets.
Minimum gain is set with the control at its full ccw position. Gain
increases as the control is rotated in a cw direction from full ccw to the
12 o'clock position. At the 12 o'clock position, both the gain and the
Sensitivity Timing Control (STC) are at their maximum values.
Additional cw rotation removes STC. At the full cw position, the gain is
at maximum and the STC is at minimum.
NOTE: STC reduces the receiver gain at the start of the trace, and
then increases it as the more distant returns are received.
With STC a uniform display of cell strength is displayed for
both near and distant cells.
A28--1146--055
REV 2
SPZ--8000 Digital Integrated Flight Control System
WARNING
R
PRIMUS 870 Weather Radar
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