The radio, no matter which type should always be connected directly to the battery via a fuse, and not to any convenient wire under the dashboard. By doing this, you will isolate any interference from the vehicle’s electrical system which could be misinterpreted as poor reception. A filter can be wired between the power supply and the transceiver to stop the interference.
The reason for putting a fuse at the battery is that if a short circuit were to occur the fuse would blow before the wires got hot and caused a fire. Spare fuses should be carried and a piece of tin foil from a cigarette box must not be treated as a fuse.
Positioning of the Radio:
The actual transceiver should be positioned so that you can see it without taking your eyes off the road and definitely should be not positioned in full sunlight (on the dashboard). If you are going to be crossing rivers consideration should be given to keeping the unit out of the anticipated water.
With all these systems it is essential that the equipment is installed professionally and correctly and the perception that the system can be installed by yourself is generally incorrect. All antennas have to be adjusted to resonate at the correct frequency and if this is done incorrectly your transceiver can malfunction and require repair from an electronic technician.
If an error is made in the wiring of the system a fire can occur with disastrous results.
Buy only well known brands as these systems are supported internationally and you should be able to obtain spares and repairs from their agents in all countries.
Remember that the most important component in the whole system is the antenna, DON’T go for the best looking —go for what works.