Which of the following might be useful in reducing RF interference to audio frequency circuits?
The correct answer is B: Bypass capacitor. What might be useful in reducing RF interference to audio frequency circuits is a bypass capacitor. Bypass capacitors provide a low-impedance path to ground for RF signals, preventing them from entering audio circuits. For amateur radio operators, this is a common RFI fix. Understanding this helps when troubleshooting RF interference.
Exam Tip
Reduce RF interference to audio = bypass capacitor. Think 'B'ypass 'C'apacitor = 'B'ypasses 'C'arrier (RF). Provides low-impedance path to ground for RF signals, preventing them from entering audio circuits. Not inductor, not diodes - just bypass capacitor.
Memory Aid
"Reduce RF interference to audio = bypass capacitor. Think 'B'ypass 'C'apacitor = 'B'ypasses 'C'arrier. Provides low-impedance path to ground for RF signals, preventing them from entering audio circuits. Common RFI fix."
Real-World Application
RF is getting into your audio amplifier, causing interference. You add a bypass capacitor (e.g., 0.01 µF) from the audio input to ground. The capacitor provides a low-impedance path for RF signals to ground, preventing them from entering the audio circuit. This is a common RFI fix.
Key Concepts
Why Other Options Are Wrong
Option A (Bypass inductor): Incorrect. Bypass inductors would block RF, not bypass it - inductors have high impedance at RF. Bypass capacitors are used, not inductors.
Option C (Forward-biased diode): Incorrect. Forward-biased diodes conduct, they don't bypass RF. Diodes aren't used for bypassing RF to audio circuits.
Option D (Reverse-biased diode): Incorrect. Reverse-biased diodes block, they don't bypass RF. Diodes aren't used for bypassing RF to audio circuits.
题目解析
The correct answer is B: Bypass capacitor. What might be useful in reducing RF interference to audio frequency circuits is a bypass capacitor. Bypass capacitors provide a low-impedance path to ground for RF signals, preventing them from entering audio circuits. For amateur radio operators, this is a common RFI fix. Understanding this helps when troubleshooting RF interference.
考试技巧
Reduce RF interference to audio = bypass capacitor. Think 'B'ypass 'C'apacitor = 'B'ypasses 'C'arrier (RF). Provides low-impedance path to ground for RF signals, preventing them from entering audio circuits. Not inductor, not diodes - just bypass capacitor.
记忆口诀
Reduce RF interference to audio = bypass capacitor. Think 'B'ypass 'C'apacitor = 'B'ypasses 'C'arrier. Provides low-impedance path to ground for RF signals, preventing them from entering audio circuits. Common RFI fix.
实际应用示例
RF is getting into your audio amplifier, causing interference. You add a bypass capacitor (e.g., 0.01 µF) from the audio input to ground. The capacitor provides a low-impedance path for RF signals to ground, preventing them from entering the audio circuit. This is a common RFI fix.
错误选项分析
Option A (Bypass inductor): Incorrect. Bypass inductors would block RF, not bypass it - inductors have high impedance at RF. Bypass capacitors are used, not inductors. Option C (Forward-biased diode): Incorrect. Forward-biased diodes conduct, they don't bypass RF. Diodes aren't used for bypassing RF to audio circuits. Option D (Reverse-biased diode): Incorrect. Reverse-biased diodes block, they don't bypass RF. Diodes aren't used for bypassing RF to audio circuits.
知识点
Bypass capacitor, RF interference, Audio frequency circuits, RFI reduction
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.