Chapter 8

What you need to know about the principles of transmission and reception

Chas E. Miller

In the previous chapter we looked at a basic valve oscillator circuit. It is possible to use this as a simple radio transmitter. If an aerial were to be connected to the top of the coil L1 and an earth to its bottom end, the oscillations produced would be radiated as electromagnetic waves, but not very effectively because the power would be low. However, high frequency amplifying stages can be used to build up the strength of the oscillations, culminating in a power output stage capable of putting out anything from a few watts to hundreds of thousands of watts into the air.

What would be sent out from such a transmitter would be a continuous series of ...

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