The normal arrangement of a c.w. transmitter is Fig. 17.1.
The buffer amplifier will be of high input impedance and operating in class A, such that it acts as a buffer or damper to the oscillator. The frequency multiplier stages, the driver, and power amplifier will be operating in class C for c.w. Subsequent filtering will be required because of the harmonics associated with class C operation.
Keying is the switching on and off of the carrier wave. Without a keying filter, interference over a wide frequency range may be caused. The effect of the components in a key-click filter are to create an RL and RC circuit which will have a time constant, and thus ‘slow down’ the rise and fall of current.
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