*Question T4B01:
What is the effect of excessive microphone gain on SSB transmissions?*  

*Correct Answer is  B: Distorted transmitted audio*  

### AI Response: (may contain errors)  

Excessive microphone gain can significantly affect Single Sideband (SSB) transmissions. Let's break down the question and the choices:

### Correct Answer: B - Distorted transmitted audio

- **Explanation**: When the microphone gain is set too high, it can cause the audio signal to clip. Clipping occurs when the amplitude of the audio signal exceeds the maximum level that the transmitter can handle, resulting in distortion. This distortion can make the transmitted audio unintelligible and can lead to poor communication quality.

### Why the Other Choices are Incorrect:

- **A: Frequency instability**  
  - **Explanation**: Frequency instability is typically related to issues with the transmitter's oscillator or power supply, not microphone gain. While excessive gain can affect the quality of the audio, it does not directly cause frequency instability.

- **C: Increased SWR**  
  - **Explanation**: Standing Wave Ratio (SWR) is a measure of how well the transmitter is matched to the antenna system. Excessive microphone gain does not affect the impedance matching of the transmitter and antenna, so it does not increase SWR.

- **D: All these choices are correct**  
  - **Explanation**: Since only option B is correct, this choice is also incorrect. Not all the listed effects occur due to excessive microphone gain.

### Summary

In summary, excessive microphone gain primarily leads to distorted transmitted audio, which is the main concern for SSB transmissions. The other options do not relate to microphone gain and are therefore incorrect. 

### Useful Rule of Thumb

- **Microphone Gain Setting**: Always adjust the microphone gain to a level where the audio is clear and free from distortion. A good practice is to monitor the transmitted audio using a receiver to ensure clarity and quality.