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No 9. Final Comments.


Our model transmitter may have seemed at times quite a complex beast but really it was somewhat unrefined and some stages that would be required for a good quality broadcast transmitter were skipped. For instance our transmitter really ought to have  a peak audio limiter to place a limit on the frequencies transmitted at a low level part of the audio amplifier. Without it, we may exceed our permissible bandwidth. We need an amplitude limiter, and possibly an automatic volume control, and most certainly a low pass filter to cut off any harmonics we may transmit at the feeder stage. This is to prevent our transmissions popping up all over the band at harmonics of our RF frequency: if we pass only the fundamental frequency and attenuate everything above we do not interfere with anybody else's transmissions. We would have to introduce cable carrying systems in as the audio we may want to transmit might well be coming from far afield, and we'd probably have to make our aerial directional so that we didn't interfere with other transmissions, in the UK or Europe. At night we'd probably have to turn our power down and so we'd need a control for that too. A modern transmitter has dozens of little whistles and bells to get the best advantage and  efficiency and stay in legality, some of which are entirely automated.

There is a wealth of information on the internet about the topic, starting here:











Which teaches you about radio communication techniques for the Amateur Radio Licences.










This is the end of the Transmitter Explanations Section.

Written by Ian Lang Sep/Oct 2010 Last update Oct 2010


Radio Principles