*Question G7B10:
Which of the following describes a linear amplifier?*  

*Correct Answer is  B: An amplifier in which the output preserves the input waveform*  

### AI Response: (may contain errors)  

A linear amplifier is a type of amplifier that ensures the output signal is a faithful reproduction of the input signal, maintaining the same waveform shape. This is crucial in applications where signal integrity is important, such as in SSB (Single Sideband) and AM (Amplitude Modulation) transmissions.

### Explanation:

1. **Correct Answer (B): An amplifier in which the output preserves the input waveform**
   - A linear amplifier maintains the linearity between input and output, meaning the output is a scaled version of the input without distortion. This is essential for accurately amplifying complex signals without altering their characteristics.

2. **Why the Other Choices are Incorrect:**
   - **Choice A: Any RF power amplifier used in conjunction with an amateur transceiver**
     - Not all RF power amplifiers are linear. Some, like Class C amplifiers, are non-linear and are used for applications where waveform fidelity is not critical.
   - **Choice C: A Class C high efficiency amplifier**
     - Class C amplifiers are non-linear and are typically used for applications like CW (Continuous Wave) and FM (Frequency Modulation) where waveform distortion is acceptable. They are not suitable for SSB or AM because they do not preserve the input waveform.
   - **Choice D: An amplifier used as a frequency multiplier**
     - Frequency multipliers are inherently non-linear devices. They intentionally distort the input signal to generate harmonics, which are then filtered to produce a higher frequency output.

### Key Points:
- **Linearity** is crucial for maintaining signal integrity in modes like SSB and AM.
- **Non-linear amplifiers** (e.g., Class C) are used where efficiency is prioritized over waveform fidelity.
- **Frequency multipliers** rely on non-linearity to function, making them unsuitable for applications requiring linear amplification.