Radio Transmitters

Any electronic device which can broadcast an electromagnetic signal, usually using the help of an antenna, is a transmitter. Broadcasting of signals such as radio, television or any other telecommunication signals use a transmitter. Signals sent from a transmitter are sent to an object or a receiver for use of communication. If that is so, a person’s vocal cords can also be called a transmitter. During the beginning of the history of radio transmitters and radio engineering, radio waves were produced from arcs called Alexanderson alternator or mechanical alternators. You can find such a specimen inside the SAQ transmitter used in Grimeton, Sweden. Later in the 1920, electronic transmitters employing the use of vacuum tubes started to be used.

The transmitters used for radio broadcasting are usually equipped with a power supply, an oscillator, a modulator to carry the signal information over to the carrier frequency to be broadcasted, and also amplifiers that are needed for Audio Frequency (AF) and Radio Frequency (RF). In many a times, a device may include a transmitter as well as a radio receiver in a single unit. This is called a transceiver, which you can find in any ordinary cell phone.

In some cases, transmitters are powered by a higher voltage transformer, than the amount of power which is required, from the power grid. This is usually done so that a constant supply of electricity can be secured. Such examples can be found in the Allouis, Roumoules and Konstantynow transmitters which are powered directly from the high-voltage network regardless of the fact that a regular, medium voltage power supply can provide enough power for the transmitter to work properly.

Transmitters usually produce some amount of heat, with bigger transmitters producing more than smaller ones. Low-voltage transmitters do not usually need a unique cooling system as modern transmitters are able to achieve efficiencies of over 98%. But then again, a broadcast transmitter conveying 98% of the energy received from a megawatt power-stage onto an antenna is somewhat an equivalent of a 20 kilowatt electric heater.

Medium-powered transmitters that use nearly a few hundred watts are cooled using air fans cooling system. For those that use a few kilowatts of power, a forced liquid cooling system is used to cool the output-stage which is quite similar to the cooling system used by an ordinary car. Because the cooling liquid comes in direct contact with the high-voltage anodes present in the tubes, distilled, deionized water or a special dielectric cooling liquid can only be used in the cooling circuits. The pure coolant is itself cooled with the help of a heat exchanger using water of regular purity. This is so because that water does not touch the energized sections of the transmitter.

Radio waves emitted from transmitters can be used to convey music, pictures, conversation, any form of data unseen through the skies. This could be happening in hundreds of thousands of various ways and usually over millions of miles. Irrespective of the fact that people are not able to see or feel radio waves in any way, they are indeed one of the factors that changed the society and the way we look at the world. If you are talking through a cell phone or cordless phone, or using a baby monitor for the safety of your child, or any other of the millions of wireless devices that you use contains radio transmitters – you should be grateful to the technology. In a way, radio transmitters are directly responsible in changing the face of the modern world, and one of the chief technology drivers that is going to continue having a major impact on lifestyle and economy for centuries to come.

This Radio Transmitters Review is Written/Updated on Sep 6th, 2010 and filed under Consumer Electronics. Both comments and pings are currently closed.

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