The Four Wheel Drive Club of Southern Africa

Two-Way Radios

Radio manufacturers use different means to identify channels and frequencies. There are three popular schemes, and you can get all the radios in a group to be on the same frequency (channel) by using this table

29MHz Channels and Frequency allocation

Channel Number

Channel Number

Channel Number

Frequency

Purpose

1 14 A 29.8725 General open ORRA/4×4 Clubs
2 16 B 29.8975 General open ORRA/4×4 Clubs
3 6 C 29.7725 Ski boat Talk frequency
4 19 D 29.9350 Ski boat Call frequency
5 11 E 29.8350 Trail Mountains
6 12 F 29.8475 Civil Defence
7 15 ¬† 29.8850 General open ORRA/4×4 Clubs
ORRA = Off Road Radio Association (FWDCSA, 4x4ATV, Land Rover Owners’ Club, Toyota Land Cruiser Club)

The channel mostly used by club members is channel 2 or channel 16 or channel B (Depending on the radio you are using).

Buying a 29 MHz radio

There are a few different makes and it may pay to shop around. Current prices for new radios are in the R600 to R1200 range. Ask advice from other FWDCSA members, particularly members of the Off-Road Rescue Unit, many of whom are qualified and licensed radio amateurs (hams).

Fitting a 29 MHz radio and antenna

The radio and antenna should be properly installed to obtain the best performance.

The radio, no matter which type, should always be connected directly to the car battery, and via a fuse. (Always carry a spare fuse). By doing this you will isolate any interference from the vehicle’s electrical system which could cause a degradation of reception. If you are going to be crossing rivers install the radio out of reach of the water.

If the antenna is not installed properly and tuned for the correct frequency, you may be unable to transmit or receive effectively, and could damage the radio.

Vertical whip antennas are the best solution for vehicles, and there are three methods of mounting on 4x4s, each with advantages and drawbacks.

Clamp-base antennas clamp onto the edge of a boot or bonnet panel. These are fragile and will be ripped off your vehicle as soon as you go into the bush.

Magnetic base antennas have the advantage of being easy to fit and remove, leaving no permanent damage to the car. The antenna can be placed in the centre of the roof at the highest part of the vehicle, resulting in a good signal, and if you have to go into a low-roofed garage, the antenna is easily removed. With some vehicles (like Land Rovers) having aluminium body panels, the magnetic base will not work. Drawbacks are that the antenna and base can be easily stolen and the antenna’s co-ax cable will have to be fed into the vehicle through the door or window and could result in noise and dust entering the vehicle on gravel roads.

Body-mounted antennas give a better result but the hole in the bodywork will be permanent. Permanently-mounted antennas can be very effectively earthed, thereby providing an effective ground plane for the antenna, resulting in a stronger signal. The antenna cable is mounted permanently and properly routed into the passenger compartment and is therefore out of the way of passengers and will not allow dust to enter.

There is a vast range of antenna manufacturers and designs to choose from. Tell your supplier that you are going off-road and select an antenna made from steel with no plastic base fittings as these will snap off the first time you drive under a branch. The antenna should be mounted as high as possible. The location of the antenna on the vehicle will also affect the radiation pattern of the signal and this must be kept in mind if you are at the limits of your reception. An antenna mounted in the centre of the roof will radiate equally in all directions. If it is mounted at the back of the roof, it will project most of the signal towards the front of the car and vice versa.

It is very important that the antenna is correctly matched to the frequency of the radio. To get the greatest amount of the radio’s output power radiated into the air, the length of the antenna has to be adjusted to ‘tune’ it to the frequency and the installation. This will need to be done by a qualified radio operator/technician with the necessary test equipment.

Hand-held low-power FM radios

These radios do not require a licence but they have a very limited range. Of the makes currently available there seems to be a substantial difference in performance and you should try to carry out your own tests if you propose to buy a pair of these. (One unit on its own would be useless unless you know someone with a similar radio, as they are not compatible with the 29 MHz AM radios. They operate in the UHF band.) They are useful for convoys.