User's Manual Part 2

34
Extending the antenna coax cable
If required, the coaxial cable may be extended with 50 ohm coaxial cable and
connectors. The maximum cable length should not exceed 100 m. Ensure that any
cable joints are well secured and waterproofed using self-amalgamating (rubber)
tape.
Cable should be RG-58 / RG-67 / RG-213 / RG-214 grade or better; connectors
should be suitable RF types (TNC, BNC, etc).
Testing the tri-channel active antenna installation
By default the NAV-7 provides a regulated 12 V DC (nom) 100 mA output to provide
power for an active antenna such as the one supplied as part of a NAV-7 System.
If you are using an alternative active antenna please check that it is compatible with
this power output. If it is not, then an external power supply interface will be
required. Your antenna supplier should be able to provide this.
WARNING
Take care not to apply power to the antenna TNC connector
from an external supply
Switch on the NAV-7 by applying power (12 V DC or 24 V DC) via a circuit breaker
or fuse.
There will be a few seconds delay whilst the software loads the contents of the
NAVTEX message store during which time the front panel red LED will blink.
The LCD display backlight will come on and the NAV-7 start-up screen will be
shown.
If the antenna fault icon appears along the top of the display, switch off immediately
and check for a short circuit at the antenna, the TNC connector or any other RF
connections in-between. If the fault persists then please follow the trouble shooting
guide in this manual.