Ham Radio General Class Practice Test

Which of the following describes a linear amplifier?

1. Any RF power amplifier used in conjunction with an amateur transceiver

2. An amplifier in which the output preserves the input waveform

3. A Class C high efficiency amplifier

4. An amplifier used as a frequency multiplier

The correct answer is: An amplifier in which the output preserves the input waveform

A linear amplifier is characterized by its ability to amplify input signals without distorting their waveform. This means that the output signal maintains the same shape as the input signal, allowing for more precise and accurate transmission of information, particularly in applications such as voice and data communications where fidelity is important. Linear amplifiers typically operate in Class A or Class AB modes, where they can handle a wide range of signal amplitudes while preserving the linearity of the output. This is crucial in ham radio applications to prevent unwanted harmonic distortion and ensure clear communication. The other options do not fully define what constitutes a linear amplifier. For instance, while an RF power amplifier can indeed be used with amateur transceivers, not all RF amplifiers are linear. Similarly, Class C amplifiers are designed for high efficiency and are typically used for continuous wave (CW) applications rather than linear amplification. Finally, amplifiers used as frequency multipliers do not preserve the original signal waveform; they generate harmonic frequencies that are multiples of the input frequency, which diverges from the linear amplification principle.