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Adjustments
6. INSTALLATION
Adjustments
After checking the unit for proper installation its time to adjust it.
To prevent possible personnet injury from radio frequency (rf) radiation hazards and scanner
rotation, be certain that no one is near the scanner b^ore tuming on the radar.
Tuning and calibrcUion of this equipment requires experience and specific technical skiils. Thus
this Work should be performed by a qualified service technician.
Initial procedures
L Press the
POWER
touchpad on the display unit, and the front panel will light up. In
approximately 1 nunute and 30 seconds, the message "ST-BY" will appear at center of the
screen. While this warmup is in process, set the
GAIN
control at 2 o'clock, and the
A/C RAIN
and
A/C SEA
Controls at fully counterciockwise.
2. When "ST-BY" appears press the TX touchpad. The radar will start transmitting, and you
will probably see some targets around you, even though the adjustments have yet to be
optimized.
3. Bring up the
GAIN
control until a small amount of noise appears on the screen.
4. Adjust the
GAIN
control on the front panel, for a little background noise showing on the
screen, and then hit the
RANGE
- touchpad several times to bring you down to the
minimum range. Without disturbing the front panel
GAIN
control, adjust the
A/C SEA
control until nearby radar targets are clearly shown on the screen. Too much A/C SEA
action will eliminate small targets, and too little A/C SEA action will cause the screen to
be so full of targets and noise that it is hard to determine which target is which as compared
to Visual sightings. Note that adjusting the
GAIN
and
A/C SEA
Controls in this manner
(GAIN
at long range,
A/C SEA
at short range) will equalize the picture at all ranges, and you will
not have to jockey back and forth with the
GAIN
control especially when you change range
scales.
Sweep timing
This adjustment ensures proper radar performance, especially on short ranges. The radar
measures the time required for a transmitted echo to travel to the target and return to the
source. The received echo appears on the CRT based on this time. Thus, at the instant the
transmitter is fired, the "Sweep" should start from the center of the CRT (sometimes called
sweep origin.)
A "trigger" pulse generated in the display unit goes to the scanner unit through the intercon-
nection cable to trigger the transmitter (magnetron). The time taken by the signal to travel
up to the scanner unit varies, depending largely on the length of interconnection cable.
During this period the display unit should wait before starting the sweep. When the display
unit is not adjusted correctly, the echoes from a straight local object (for example, a harbor
wall or straight pier) will not appear with straight edges—namely, they will be seen as
"pushed out" or "pulled in" near the picture center. The range of objects will also be
incorrectly shown.
6-15
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Troubleshooting
