Common problems caused by incorrect installation are listed in Table 18.
WARNING Poor installation can damage the antenna such that a replacement is needed.
Table 18: Possible faults in the installation Symptoms Possible causes Action
Antenna detunes Inadequate support of the antenna.
Ensure the antenna has adequate support so it does not sway or sag. If required, use antenna supports such as guyed masts (see page 34, Antenna supports in a fixed station).
Improve the earth connection (see page 49, Grounding the antenna and page 50, Grounding the tuner (fixed station only)).
Ensure a good earth connection to the vehicle body is provided by an earth braid or copper strap, keeping it as short as possible.
Check the vehicle earth on metal areas close to the antenna and rectify if necessary, for example, the bonnet of the vehicle may be isolated from the main vehicle earth.
If the problem persists, shorten or lengthen the coaxial cable between the antenna and the transceiver by approximately 1 m (1 yd). Check that the problem does not move to other channels.
Incorrect positioning of the antenna.
Check that the position of the antenna corresponds to the desired direction of communication. The antenna must also be positioned away from trees, buildings etc, which provide a shielding effect and diminish the efficiency of the antenna. With an SWR meter in place, alter the position of the antenna to achieve best forward radiated power (see page 68, Voltage standing wave ratio).
Inadequate support of the antenna.
Ensure the antenna is adequately supported, so that it does not sway or sag. If required, use antenna supports such as guyed masts (see page 34, Antenna supports in a fixed station).
The antenna may have been tuned without the whip in place.
Ensure the whip is in place before tuning.
Antenna tunes when
Ensure correct installation and tuning procedures are followed.
With an SWR meter in place, alter the position of the antenna to achieve best forward radiated power (see page 68, Voltage standing wave ratio). Carry out all testing in the open, away from trees and buildings etc.
Leaning the antenna away from the bodywork sometimes assists in tuning. Check that the problem does not move to other channels.
Improve the earth of the transceiver by connecting an earthing strap (braid or copper strip) from the earth screw of the transceiver to the vehicle chassis, keeping the strap as short as possible (see page 47, Grounding the
transceiver).
Noise interference Noise interference by other equipment.
Identify the source of interference by switching other equipment off. If possible, move the transceiver and/or antenna away from the noise source.
Inadequate earthing of the transceiver.
Improve the earth of the transceiver by connecting an earthing strap (braid or copper strip) from the earth screw of the transceiver to the earthing point, keeping the strap as short as possible (see page 47, Grounding the
transceiver).
No power The internal fuse of the transceiver has blown.
Replace the fuse.
Poor connections. Check the connections from the battery to the transceiver, ensuring that they are connected correctly.
Power not switched on.
Check that the switch is on at the AC mains supply and the transceiver supply.
Battery not supplying the correct voltage, or is in poor condition.
Check battery supply (see page 53, Checking the battery).
Incorrect cable connections.
Check the connections from the AC mains supply to the transceiver supply, and from the transceiver supply to the transceiver. Ensure that the cables are connected
correctly.
Faulty cables and/or connectors.
Check that the cables and connectors between all items of equipment are securely connected and not damaged. If the cables or connectors are faulty, contact your Codan Table 18: Possible faults in the installation (cont.)
Symptoms Possible causes Action
Poor radiation efficiency
Poor installation. Improve the earth connection (see page 49, Grounding the antenna).
Incorrect positioning of the antenna.
Check the position of the antenna, ensuring that the vehicle body is not acting as a shield.
Check that the position of the antenna corresponds to the desired direction of communication. The antenna must also be positioned away from trees, buildings etc, which provide a shielding effect and diminish the efficiency of the antenna. With an SWR meter in place, alter the position of the antenna to achieve best forward radiated power (see page 68, Voltage standing wave ratio).
If the problem persists, check the antenna length (for long wire antennas), the length of the antenna feed wire, and the conductivity of the grounding system. Alter these slightly in an attempt to achieve better tuning. Check that the problem does not move to other channels.
The antenna and/or tuner may not be earthed correctly.
Improve the earth connection (see page 49, Grounding the antenna and page 50, Grounding the tuner (fixed station only)).
Table 18: Possible faults in the installation (cont.) Symptoms Possible causes Action
SWR is bad The SWR
Ensure the SWR meter is connected to the coaxial line at the base of the antenna to achieve an accurate reading (see page 68, Voltage standing wave ratio).
The antenna may not be positioned
correctly.
Check the position of the antenna, ensuring that the vehicle body is not acting as a shield. With an SWR meter in place, alter the position of the antenna to achieve best forward-radiated power (see page 68, Voltage standing wave ratio).
Check that the position of the antenna corresponds to the desired direction of communication. The antenna must also be positioned away from trees, buildings etc, which provide a shielding effect and diminish the efficiency of the antenna. With an SWR meter in place, alter the position of the antenna to achieve best forward-radiated power (see page 68, Voltage standing wave ratio).
Faulty coaxial cable
Improve the earth connection (see page 49, Grounding the antenna and page 50, Grounding the tuner (fixed station only)).
Check that all the connections between the units of the station are correct and secure.
Faulty cables and/or connectors.
Check that the cables and connectors are securely connected and not damaged. If the cables or connectors are faulty, contact your Codan representative.
Table 18: Possible faults in the installation (cont.) Symptoms Possible causes Action
Tuning fails Inadequate earthing. Antenna mounting bracket should be welded or bolted directly to the chassis.
All paint should be cleaned from mating surfaces.
The earth braid provided should be connected to an independent grounding point going to the bodywork of the vehicle, or to the battery negative if possible.
Improve the earth of the transceiver by connecting an earthing strap (braid or copper strip) from the earth screw of the transceiver to the earthing point, keeping the strap as short as possible (see page 47, Grounding the
transceiver).
Voltage drop in either the fuse, the control leads, or the battery
Voltage less than 12 V DC.
Check the voltage; it must be greater than 12 V DC on transmit.
Table 18: Possible faults in the installation (cont.) Symptoms Possible causes Action