What is the effect of excessive microphone gain on SSB transmissions?
The correct answer is B: Distorted transmitted audio. Excessive microphone gain on SSB transmissions causes distorted transmitted audio. When the microphone gain is set too high, the audio signal level exceeds what the transmitter can properly handle, causing overmodulation and distortion.
SSB transmitters have a maximum modulation level. When microphone gain is too high, the audio input signal is too strong, and the transmitter tries to modulate beyond its capability. This causes clipping and distortion of the transmitted audio. The solution is to reduce microphone gain to a level where the audio is clear and undistorted. Proper microphone gain adjustment is important for good SSB audio quality.
Exam Tip
Excessive mic gain SSB = Distorted audio. Remember: Too much microphone gain on SSB causes distorted transmitted audio due to overmodulation. Reduce gain for clear audio.
Memory Aid
"**E**xcessive **M**ic **G**ain = **E**xcess **M**odulation **G**arbled (think 'EMG = EMG' = Excess Modulation Garbled)"
Real-World Application
You're operating SSB and other operators tell you your audio sounds distorted, especially on voice peaks. You check your microphone gain setting and find it's turned up too high. You reduce the microphone gain, and your transmitted audio becomes clear and undistorted. The excessive gain was causing overmodulation, which clipped your audio signal and created distortion.
FCC Part 97.307Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Excessive microphone gain doesn't cause frequency instability. Frequency stability is related to the transmitter's oscillator, not microphone gain.
Option C: Incorrect. Microphone gain doesn't affect SWR. SWR is related to antenna impedance match, not audio levels.
Option D: Incorrect. Not all options are correct. Only audio distortion is caused by excessive microphone gain.
题目解析
The correct answer is B: Distorted transmitted audio. Excessive microphone gain on SSB transmissions causes distorted transmitted audio. When the microphone gain is set too high, the audio signal level exceeds what the transmitter can properly handle, causing overmodulation and distortion. SSB transmitters have a maximum modulation level. When microphone gain is too high, the audio input signal is too strong, and the transmitter tries to modulate beyond its capability. This causes clipping and distortion of the transmitted audio. The solution is to reduce microphone gain to a level where the audio is clear and undistorted. Proper microphone gain adjustment is important for good SSB audio quality.
考试技巧
Excessive mic gain SSB = Distorted audio. Remember: Too much microphone gain on SSB causes distorted transmitted audio due to overmodulation. Reduce gain for clear audio.
记忆口诀
**E**xcessive **M**ic **G**ain = **E**xcess **M**odulation **G**arbled (think 'EMG = EMG' = Excess Modulation Garbled)
实际应用示例
You're operating SSB and other operators tell you your audio sounds distorted, especially on voice peaks. You check your microphone gain setting and find it's turned up too high. You reduce the microphone gain, and your transmitted audio becomes clear and undistorted. The excessive gain was causing overmodulation, which clipped your audio signal and created distortion.
错误选项分析
Option A: Incorrect. Excessive microphone gain doesn't cause frequency instability. Frequency stability is related to the transmitter's oscillator, not microphone gain. Option C: Incorrect. Microphone gain doesn't affect SWR. SWR is related to antenna impedance match, not audio levels. Option D: Incorrect. Not all options are correct. Only audio distortion is caused by excessive microphone gain.
知识点
Microphone gain, SSB, Audio distortion, Overmodulation
Verified Content
Question from official FCC Technician Class question pool. Explanation reviewed by licensed amateur radio operators.