Why is automatic level control (ALC) used with an RF power amplifier?
The correct answer is C: To prevent excessive drive. Why automatic level control (ALC) is used with an RF power amplifier is to prevent excessive drive. ALC monitors the drive level and reduces it if it becomes too high, protecting the amplifier. For amateur radio operators, this prevents damage from overdriving the amplifier. Understanding this helps when operating with amplifiers.
Exam Tip
ALC purpose = prevent excessive drive. Think 'A'LC = 'A'voids 'L'ethal 'C'urrent (excessive drive). Monitors drive level and reduces it if too high, protecting amplifier. Not audio response, not harmonics, not efficiency - just drive protection.
Memory Aid
"ALC purpose = prevent excessive drive. Think 'A'LC = 'A'voids 'L'ethal 'C'urrent. Monitors drive level and reduces it if too high, protecting amplifier from damage. Primary purpose is drive protection."
Real-World Application
You drive an RF power amplifier. ALC monitors the drive level. If you increase drive too much, ALC automatically reduces it to prevent excessive drive that could damage the amplifier. ALC protects the amplifier by limiting drive to safe levels. This is its primary purpose.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. ALC doesn't balance audio frequency response - that's done by audio processing. ALC is about drive level, not audio response.
Option B: Incorrect. ALC doesn't reduce harmonic radiation - that's done by filters and proper tuning. ALC is about drive level.
Option D: Incorrect. ALC doesn't increase overall efficiency - it may actually reduce efficiency slightly by limiting drive. ALC is for protection, not efficiency.
题目解析
The correct answer is C: To prevent excessive drive. Why automatic level control (ALC) is used with an RF power amplifier is to prevent excessive drive. ALC monitors the drive level and reduces it if it becomes too high, protecting the amplifier. For amateur radio operators, this prevents damage from overdriving the amplifier. Understanding this helps when operating with amplifiers.
考试技巧
ALC purpose = prevent excessive drive. Think 'A'LC = 'A'voids 'L'ethal 'C'urrent (excessive drive). Monitors drive level and reduces it if too high, protecting amplifier. Not audio response, not harmonics, not efficiency - just drive protection.
记忆口诀
ALC purpose = prevent excessive drive. Think 'A'LC = 'A'voids 'L'ethal 'C'urrent. Monitors drive level and reduces it if too high, protecting amplifier from damage. Primary purpose is drive protection.
实际应用示例
You drive an RF power amplifier. ALC monitors the drive level. If you increase drive too much, ALC automatically reduces it to prevent excessive drive that could damage the amplifier. ALC protects the amplifier by limiting drive to safe levels. This is its primary purpose.
错误选项分析
Option A: Incorrect. ALC doesn't balance audio frequency response - that's done by audio processing. ALC is about drive level, not audio response. Option B: Incorrect. ALC doesn't reduce harmonic radiation - that's done by filters and proper tuning. ALC is about drive level. Option D: Incorrect. ALC doesn't increase overall efficiency - it may actually reduce efficiency slightly by limiting drive. ALC is for protection, not efficiency.
知识点
ALC, Automatic level control, Excessive drive, Amplifier protection
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.