What could be a symptom caused by a ground loop in your station’s audio connections?
The correct answer is A: You receive reports of 'hum' on your station's transmitted signal. A symptom caused by a ground loop in your station's audio connections is that you receive reports of 'hum' on your station's transmitted signal. Ground loops can cause 60 Hz (or 50 Hz) hum that gets into your audio and is transmitted. For amateur radio operators, this is a common ground loop symptom. Understanding this helps identify ground loop problems.
Exam Tip
Ground loop symptom = hum on transmitted signal. Think 'G'round 'L'oop = 'G'enerates 'L'ow-frequency hum (60 Hz). Ground loops cause 60 Hz hum that gets into audio and is transmitted. Not high SWR, not excessive current, not harmonics - just hum.
Memory Aid
"Ground loop symptom = hum on transmitted signal. Think 'G'round 'L'oop = 'G'enerates 'L'ow-frequency hum. Ground loops cause 60 Hz hum that gets into audio and is transmitted. Characteristic ground loop symptom."
Real-World Application
You have a ground loop in your station's audio connections. Other operators report hearing 60 Hz hum on your transmitted signal. The ground loop causes the hum to get into your audio chain and be transmitted. Fixing the ground loop eliminates the hum.
Key Concepts
Why Other Options Are Wrong
Option B: Incorrect. Ground loops don't cause high SWR - SWR is about antenna matching, not ground loops. High SWR is a different problem.
Option C: Incorrect. Ground loops don't cause excessive current draw - that's a different problem. Excessive current isn't a ground loop symptom.
Option D: Incorrect. Ground loops don't cause harmonic interference - harmonics come from non-linear operation, not ground loops. Harmonics are different.
题目解析
The correct answer is A: You receive reports of 'hum' on your station's transmitted signal. A symptom caused by a ground loop in your station's audio connections is that you receive reports of 'hum' on your station's transmitted signal. Ground loops can cause 60 Hz (or 50 Hz) hum that gets into your audio and is transmitted. For amateur radio operators, this is a common ground loop symptom. Understanding this helps identify ground loop problems.
考试技巧
Ground loop symptom = hum on transmitted signal. Think 'G'round 'L'oop = 'G'enerates 'L'ow-frequency hum (60 Hz). Ground loops cause 60 Hz hum that gets into audio and is transmitted. Not high SWR, not excessive current, not harmonics - just hum.
记忆口诀
Ground loop symptom = hum on transmitted signal. Think 'G'round 'L'oop = 'G'enerates 'L'ow-frequency hum. Ground loops cause 60 Hz hum that gets into audio and is transmitted. Characteristic ground loop symptom.
实际应用示例
You have a ground loop in your station's audio connections. Other operators report hearing 60 Hz hum on your transmitted signal. The ground loop causes the hum to get into your audio chain and be transmitted. Fixing the ground loop eliminates the hum.
错误选项分析
Option B: Incorrect. Ground loops don't cause high SWR - SWR is about antenna matching, not ground loops. High SWR is a different problem. Option C: Incorrect. Ground loops don't cause excessive current draw - that's a different problem. Excessive current isn't a ground loop symptom. Option D: Incorrect. Ground loops don't cause harmonic interference - harmonics come from non-linear operation, not ground loops. Harmonics are different.
知识点
Ground loops, Hum, Transmitted signal, Audio connections
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.