TM 11-5840-360-14-1-1
3.7.5 VRM Control
WARNING
This control adjusts the diameter of the variable
PRIMARY POWER IS PRESENT AT
range ring on the PPI to read any range from
THE
INDICATOR,
RECEIVER
approximately 5 to approximately 130,000 yards.
TRANSMITTER,
AND
EVEN WITH THE INDICATOR POWER
3.7.6 CURSOR Control
SWITCH SET TO OFF.
DO NOT
PERFORM ANY ADJUSTMENTS OR
This control rotates the cross-hair bearing cursor
MAINTENANCE UNLESS THE SHIP'S
through 3600 to provide an accurate indication of echo
POWER DISCONNECT SWITCH TO
bearing.
THE RECEIVER TRANSMITTER (AND
TO THE INDICATOR IF SEPARATE
3.7.7 PNL LIGHTS, BRG SCALE, RANGE RINGS
SWITCHES ARE USED) IS OFF.
Controls
3.7.2 Transmit Indicator
These controls vary the brightness of: (1) the
control panel lamps and plotter lamps; (2) the bearing
The transmit indicator (connected in parallel
scale and cursor lamps; and (3) the range markers.
with one on the receiver transmitter) is off when primary
power is removed from the radar. It glows steadily when
3.7.8 BRILLIANCE Control
the transmitter is on, and flashes when the transmitter is
in standby. The transmit indicator flashes when the
Adjusts the brilliance of the PPI display.
POWER switch is in TX ON and the timer has not run
down, or when the system contains a fault.
3.7.9 RANGE SELECT Switch
3.7.3 CONTRAST Control
Selects any of the 11 ranges. The shortest
range that covers the desired area should be used.
The CONTRAST control is a video gain control
Range is increased by clockwise rotation and decreased
which adjusts the brightness of the digital video only and
by counterclockwise rotation of the switch. The selected
has no effect on the brightness of the range rings or the
range is illuminated on the RANGE MILES scale of the
VRM ring. The correct setting of this control produces a
selector knob; the value of the corresponding range
PPI display on which all targets are visible with an
rings is displayed on the MARK scale. Range and mark
optimum two-level brightness differential between strong
information is also displayed by indicators located above
and weak returns.
As the control is turned
the PPI screen.
counterclockwise, the video gain is decreased causing
all target returns to become dimmer. As a result, weak
3.7.10 PWR BOOST Switch
target returns become so dim that they are barely
visible, and in some cases, disappear completely from
When held in the ON position, system operation
the PPI. If rotation is continued in the counterclockwise
is changed from short pulse to medium pulse on the 3-
direction, all video returns eventually disappear from the
mile range to improve reception of small or weak
screen.
When the CONTRAST control is turned
echoes near the limit of that range. The switch returns
clockwise, the brightness of all digital video is increased.
to the OFF position when released.
Strong target returns become much brighter and weak
returns which were not displayed before are now visible.
NOTE:
If the control is turned fully clockwise, all target returns
(weak and strong) are displayed with a high degree of
Because of the operating parameters
brightness and may appear slightly out of focus.
of the power supply protection
features,
the
transmitter
may
3.7.4 VRM and READOUT Controls
occasionally shut down when the
system is switched from 3 to 6 miles,
The inner control (VRM) adjusts the intensity of
or when PWR BOOST is selected.
the variable range ring displayed on the PPI. The outer
This will result in blanking of echoes
control (READOUT) adjust the brightness of the VRM
for the first 2 to 3 sweep rotations.
digital readout corresponding to the size of the variable
This is entirely normal; echoes will
range ring.
reappear automatically at the end of
6 seconds.
3-10
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