9c.1 Understand that operating in vehicles and vessels can introduce
new hazards (i.e.insecure equipment, long/flexible antennas, accidental
shorts to earth, lack of attention to driving, RF induction into
vehicle control circuits).
Let us look at the hazards listed in the syllabus:
- Insecure
equipment - If you brake suddenly insecure equipment could hit you,
damage the vehicle, cause wires to come loose, possibly being earthed
and blowing fuses, obscure you view of the road and causing distraction
- Long
flexible antennas - These can whip around causing rapid changes in SWR,
they can catch low roofs in car parks, break fluorescent tubes, they
may come into contact with pedestrians, cause excessive strains on
antenna mounts which may break causing the antenna to separate from the
vehicle. They may catch low bridges.
- Accidental
shorts to earth - if properly fused, the fuses will blow. Without
adequate fusing the flow of current could cause overheating and
possible fire and or fumes. Remember that a car battery can supply a
high current which is likely to cause overheating. there is also a risk
of shorts to earth causing electronic control systems to fail.
- Lack
of attention to driving - always a risk when
trying to operate a radio and drive a vehicle at the same time.
Preferably everything should be set up on a single frequency with a
neck mike or fixed mike rather than a hand held mike. Radio controls
should be easily
accessible. For example using a detachable head connected to the
dashboard where it does not obscure the driver's view and ability to
operate car controls. Avoid having to carry out complex operations such
as going into menus to change the radio controls. Learn how to change
frequency, volume, mode etc without having to take your eye off the
road. Make sure the radio readout is not too bright when carrying out
night time driving
- RF
induction into
vehicle control circuits - Modern vehicles have many electronic
controls systems. Try to route cables well away from these and the
wires running to them to avoid inducing Rf currents into the control
system.
Recall the additional safety precautions that should be taken whilst
operating mobile and/or maritime mobile (i.e. secure equipment, cable
routing/protection, correct fusing, use of hands-free equipment,
attention to good radio housekeeping).
- Secure equipment - in
addition to the hazards mentioned above, operating maritime mobile may
involve movement of the vessel and so extra precautions are required to
hold the equipment in place
- Cable routing - try to
keep the antenna as far away from the vehicles electric control systems
as possible. Keep 12/28 volt power cables as short as possible with a
direct run back to the battery for both the positive and negative
cables. Route neck mikes and similar cables so that they do not get in
the way of driving the vehicle.
- Cable protection - It
is not a good idea to route power cables under carpets. It may look
better and prevent passengers catching their feet in them, but if the
cable gets warm the good insulation could speed up the possibility of a
fire. keep the cables in the air, but out of the way. Where cables pass
through holes use a grommet to stop the cable chafing and losing its
insulated coating. When passing power cables through the bulkhead from
the engine compartment to the body of the vehicle be careful not to
damage existing cables passing through the holes. In maritime mobile
conditions ensure that cables and earthing points are not subject to
the ingress of salt water which would lead to rapid corrosion.
- Correct fusing - again
check that equipment has the correct fuse. It is a good idea to fuse
the power cables near to the battery with the correct fuse in a
waterproof case. Although the 12v accessory socket used for
providing 12volts near the driver and sometimes in the boot of vehicles
looks a convenient source of power, it is best not to use these for
radio equipment as the wires to them will be in a wiring harness which
could easily spread rf interference as it meanders around the car! In
addition the power available will certainly not run a 100W transceiver!
- Use
of hands free equipment - as mentioned above there are is a variety of
neck mikes and ear mikes that do not require the operator to hold a
fist mike. TX/RX switches can be attached to gear sticks as can volume
controls and channel changing switches
- Attention to good
housekeeping - the risk of accidents will be reduced by applying the
above precautions. Plan your mobile set up carefully and try it out
when the vehicle is stationary before you try it mobile. If at anytime
you feel unsafe analyse the problem and try to overcome it. I have
found that there are some occasions when you just need to turn off the
radio and concentrate on the driving. However on long runs on motorways
a good mobile set up can help to keep you awake although there are some
who would disagree!
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