Why do most amateur stations use lower sideband on the 160-, 75-, and 40-meter bands?
The correct answer is D: It is commonly accepted amateur practice. Most amateur stations use lower sideband on the 160-, 75-, and 40-meter bands because it is commonly accepted amateur practice. This is a convention that developed over time - there's no technical reason LSB is better than USB on these bands, but everyone uses LSB, so you must use it too for compatibility. For amateur radio operators, following this convention ensures you can communicate with others. Understanding this helps explain operating conventions.
Exam Tip
LSB on 160m, 75m, 40m = commonly accepted practice. Think 'L'ower 'S'ideband = 'L'ongstanding 'S'tandard practice. It's a convention everyone follows for compatibility. Not about efficiency, legality, or AM compatibility - just accepted practice.
Memory Aid
"LSB on 160m, 75m, 40m = commonly accepted practice. Think 'L'ower 'S'ideband = 'L'ongstanding 'S'tandard. It's a convention for compatibility. Not about efficiency or legality - just what everyone does."
Real-World Application
You operate SSB on 40 meters. Everyone uses lower sideband - it's the accepted convention. There's no technical reason LSB is better, but since everyone uses it, you must too for compatibility. If you used USB, your signal would be on the wrong side of the carrier, and others couldn't copy you.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. LSB isn't more efficient than USB at these frequencies - both are equally efficient. The choice is convention, not efficiency.
Option B: Incorrect. LSB isn't the only legal sideband - USB is also legal. The choice is convention, not regulation.
Option C: Incorrect. LSB compatibility with AM detectors isn't the reason - modern receivers don't use AM detectors for SSB. The reason is convention.
题目解析
The correct answer is D: It is commonly accepted amateur practice. Most amateur stations use lower sideband on the 160-, 75-, and 40-meter bands because it is commonly accepted amateur practice. This is a convention that developed over time - there's no technical reason LSB is better than USB on these bands, but everyone uses LSB, so you must use it too for compatibility. For amateur radio operators, following this convention ensures you can communicate with others. Understanding this helps explain operating conventions.
考试技巧
LSB on 160m, 75m, 40m = commonly accepted practice. Think 'L'ower 'S'ideband = 'L'ongstanding 'S'tandard practice. It's a convention everyone follows for compatibility. Not about efficiency, legality, or AM compatibility - just accepted practice.
记忆口诀
LSB on 160m, 75m, 40m = commonly accepted practice. Think 'L'ower 'S'ideband = 'L'ongstanding 'S'tandard. It's a convention for compatibility. Not about efficiency or legality - just what everyone does.
实际应用示例
You operate SSB on 40 meters. Everyone uses lower sideband - it's the accepted convention. There's no technical reason LSB is better, but since everyone uses it, you must too for compatibility. If you used USB, your signal would be on the wrong side of the carrier, and others couldn't copy you.
错误选项分析
Option A: Incorrect. LSB isn't more efficient than USB at these frequencies - both are equally efficient. The choice is convention, not efficiency. Option B: Incorrect. LSB isn't the only legal sideband - USB is also legal. The choice is convention, not regulation. Option C: Incorrect. LSB compatibility with AM detectors isn't the reason - modern receivers don't use AM detectors for SSB. The reason is convention.
知识点
Lower sideband, LSB convention, Operating practice, Amateur conventions
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.