User's Manual Part 2

Testing the Banten active antenna

If it is suspected that reception is being compromised by the antenna performance,

the antenna should be checked for electrical damage.

Disconnect the antenna from the NAV-7 by unscrewing the TNC connector at the

back of the NAV-7.

Using a DVM set on resistance, measure across the TNC RF connector from the

centre pin to the outer ferrule, looking back up towards the antenna. DO NOT

ATTEMPT TO MEASURE THE RESISTANCE OF THE TNC SOCKET ON THE

NAV-7.

A good antenna will show a reading in the range 1500 – 2000 ohms.

A failed antenna will show a reading < 1000 ohms.

If a reading of greater than 5000 ohms is measured, then there is a continuity

problem with the connector or cable; these should be checked for damage or

misconnection.

Note that these resistance values only apply to a Banten active antenna as supplied

by McMurdo. Other active antennas will have different resistance readings; consult

the supplier in order to check such antennas.

Testing a passive antenna installation

The NAV-7 regulated 12 V DC 100 mA output can be disabled for passive antenna

installations or for installations using a matching transformer.

NOTE: This should be done the first time that power is applied to the NAV-7

BEFORE the antenna is connected.

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.