9. Power Amplifier

TODO: work in progress

Definitions

• Power Amplifier takes the output from the exciter which is usually very low and amplifies the signal before passing it to the aerial
• Modulation is the process of impressing speech on to the carrier wave
• ATU is aerial tuning unit is a device connected between a radio transmitter or receiver and its antenna to improve power transfer between them by matching the impedance of the radio to the antenna’s feedline.

Diagrams

• Spectrogram and waterfall of a transmitted signal on 145.5 MHz, showing harmonics

Circuit diagrams

• Circuit of Icom IC-718’s Power Amplifier

Graphs

Notes

Power Amplifier

• no frequency change within a P.A.
• very important to ensure that self-oscillation does not take place
• Class of oscillation decided based on the modulation scheme (Class C for FM, AB for SSB)
• Harmonics must be suppresed to avoid unintended interference