With too little gain, some weak echoes are
3.7.18 HD UP/GYRO STAB/HDG SET Switch
missed, and there is a decrease in the range at which
objects can be detected.
With excessive gain,
This switch is supplied as part of the North
additional echoes are not seen, but the contrast between
Stabilized Presentation option. In the HD UP position,
echoes and the background noise signals is reduced,
the heading line flashes at 0relative at every revolution
making observation more difficult.
of the sweep trace on the PPI. In the GYRO STAB
position, North always appears at the 0 position, and
A temporary setting at lower or higher than
the heading line flashes to indicate ship's true heading.
normal gain may be useful in detecting significant
The HDG SET position is selected to automatically
echoes. For example, with the GAIN control at its
synchronize the sweep orientation with the ship's gyro.
normal setting, "clutter" from rain or snow may obscure
the echo from a nearby ship (or other object) within a
3.7.19 COMPASS Control (16-Inch Indicator Only)
squall or storm. Reducing the gain temporarily will
usually permit the stronger and more distinct ship echo
Provides manual rotation of the true bearing
to override the "clutter". However, detection of objects
ring when the TBK (optional) is not installed.
beyond the squall or storm may require a higher GAIN
control setting than normal. At the longer range,
3.7.20 EBL DIM/EBL READ Switch
"clutter" may attenuate, but not completely obscure,
echoes from distant objects.
EBL DIM controls the brightness of the EBL.
EBL READ returns the EBL origin to the center of the
3.7.15 TUNE Control and Indicator
display when the radar is in the offset mode.
The TUNE control and indicator operate from
3.7.21 EBL Control
signals integrated over the first mile of range only. For
correct operation, the RANGE SELECT switch should
Controls the azimuth position of the electronic
be set to either the 6 or 12 mile range and the ANTI-
CLUTTER SEA control adjusted counterclockwise until a
presentation is observed on the screen. The TUNE
3.7.22 TGT MARK Pushbutton/EBL ORIGIN
control is now adjusted near the center of its range until
the TUNING indicator glows at maximum average
brightness. The indicator will brighten and dim as the
This combination control is supplied with the
tuning comes on and off peak. Tuning may also be
TM/CPA option and the Collision Avoidance System
accomplished by observing a weak. isolated echo and
option. The joystick portion of the control is used to
rotating the TUNE control until the echo is maximized.
position a reference spot over a target of interest on the
PPI screen. The TGT MARK button is now pushed to
3.7.16 ANTENNA Switch
identify that target for future reference in course plotting.
3.7.23 OFFSET Switch
This spring loaded switch is normally in the ON
position and is used to apply rotation power to the
antenna. When held in the OFF position, power is
Allows ship's position to be offset by 70% of
removed from the antenna motor, and the antenna stops
CRT radius (astern only). This permits an expanded
The brightness of the PPI display also
view of the area ahead of the ship without giving up the
decreases since the automatic dimming feature of the
advantages of being on the shortest range possible. No
radar is activated.
offset is available on the 48 or 64 mile ranges.
3.7.17 INTRF REJECT Switch
No other controls, including those
circuit (optional) which functions to cancel the display of
adjusted by screwdriver, may be
moved or adjusted by unauthorized
operating within reception range.