NT-2000 REF Manual
Installation
7-3
7.2. Antenna Installation
The dimensions of the active antenna (ANT–2000) is given in Figure 7–3. The same
dimensions apply to the optional active antennas (ANT–900 and ANT–2002). If a long
wire is to be used permanently, it should be insulated and at least five meters long.
7.2.1. Installation Site Requirements
Active Antenna
For best results and a prolonged service life, the active antenna unit should be installed:
・ at a site free from continuous, heavy shocks and vibrations,
・ away as much as possible from the feedpoint or radiating elements of HF/MF
communications antennas, radar scanners and INMARSAT antennas, and
・ away as much as possible from, and above, any metallic obstructions.
< WARNING >
LOCATING THE ACTIVE ANTENNA CLOSE TO THE FEED POINT OR
RADIATING ELEMENTS OF AN HF/MF TRANSMITTING ANTENNA CAN
DESTROY THE PREAMPLIFIER IN THE CYLINDRICAL HOUSING.
Long Wire Antenna
・ A long wire antenna should be of insulated type and at least 5 meters long. Bare wire
can short–circuit the antenna to ground and must not be used.
Before connecting the wire to the appropriate rear apron antenna connector, ask
your dealer/qualified service engineer to change the internal wiring (two jumpers)
on each receiver PCB in the cabinet and on the frequency converter board in the rear
apron so that an input impedance match is achieved and that no DC voltage is
present on the connector’s center conductor.
・ For best results, the wire should be raised as high as possible from the ground, and
as much away as possible from nearby walls or surrounding structures as well as
from the onboard devices listed above, or very poor, noisy reception will result.
7.2.2. Precautions for Cabling
・ To minimize the effect of interference from other onboard electronics, the coaxial
cable from the antenna unit should not be run close to, and in parallel with, transmit
antenna feed lines, radar waveguides, echo sounder transducer cables, control cables,
power cables, etc. from such equipment. The same requirements apply to the routing
of the long wire antenna.
・ If the cable is extended with coaxial connectors ( e.g. PL–258/PL–259 pairs), be sure
to make the junctions waterproof using self–bonding tape or other appropriate
sealant.
< WARNING >
THE CENTER CONDUCTOR OF THE COAXIAL CABLE IS AT +8 VDC (OR AT +12V
WHEN WORKING ON 4209.5 KHZ) WITH THE EQUIPMENT SWITCHED ON. DO
NOT SHORT THE CENTER CONDUCTOR TO GROUND OR DAMAGE TO THE
POWER SUPPLY PCB CAN RESULT.
< CAUTION >
Water intrusion into the coax cable will seriously degrade the reception performance.
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