Tropical Band DX And Noise

Turn your receiver on and, in an ideal world, you will hear only the stations that are on the frequency to which you are tuned. That, at least, is the theory.

In practice, this is far from the case for, whenever you switch on, you're greeted by a barrage of noise that swamps all but the strongest of signals. Reducing this noise to enable you to hear the stations you want provides a major contribution to identifying DX.

Natural noise
Noise is produced by many natural processes all the way from thunderstorms happening anywhere around the Earth to the signals we receive from the sun and the background radiation that is always present from the galaxy.

Since this noise is produced by natural processes there is little you can do to minimise it.

Man-made noise
This noise is caused by the many electrical devices in operation at only one time around us from car ignition systems all the way to TVs, washing machines and electric hairdryers.

Almost any device that uses electricity, particularly if it has some form of electric motor, will emit electromagnetic energy which is received by our antenna as radio waves.

A year or so back I spent a very relaxing week deep in the heart of the English countryside and was amazed at how quiet the bands were. There was very little background noise and signals seemed to be many times louder and easier to hear.

Devices in your own home
With the radio on, try turning off the various electrical units in your home that you can safely turn off and see how much difference this makes to the level of overall noise. You might find that a particular appliance, like a TV, may be making a noticeable noise.

Devices outside your home
There is little you can do about this but it may be possible to carry your radio around the house and see how the noise level changes from room to room. Often there is a room or position where the noise is lessened.

If you can be sure that noise is caused by a neighbour then a friendly approach might be met with a helpful attitude that will help to find the source of the problem.

Time of day
Early in the morning or late at night are times when traditionally the environment is electrically quieter and it is worth using these times to listen if you can.

Noise blanker
Some radios have a noise blanker fitted and, although of limited use, it is worth trying to see if will make stations easier to hear.

In my experience noise blankers seem to have little, if any, effect but your experience may be better.

Batteries rather than mains electricity
The mains electricity supply is well known for carrying around interference and noise so try operating with batteries and see if this creates better listening. Using rechargeable batteries can then become a regular feature of your listening.

Antenna
An external antenna, if one can be fitted, positioned well away from anything that might make electrical noise can have the combined effect of increasing signal strength and picking up less interference.

As time goes on the effect of man-made noise is making the reception of signals on the short wave bands harder and harder. Try the measures suggested above and see if you can reduce the noise or, to see how quiet it really can be, take your radio out into the countryside well away from people and see the difference.