What would cause a broadcast AM or FM radio to receive an amateur radio transmission unintentionally?
The correct answer is A: The receiver is unable to reject strong signals outside the AM or FM band. A broadcast AM or FM radio receiving an amateur radio transmission unintentionally is caused by fundamental overload - the receiver cannot reject strong signals outside its intended band. When a strong amateur signal (even on a different frequency) is near the broadcast receiver, it can overload the receiver's front-end, causing it to receive the signal even though it's outside the AM or FM band. This is a receiver problem, not a transmitter problem. For amateur radio operators, understanding this helps when neighbors report interference - the issue is often their receiver's lack of filtering, not your transmitter's output.
Exam Tip
Broadcast receiver picking up amateur signal = receiver overload. Think 'R'eceiver 'O'verload = 'R'eceiver can't 'O'reject strong signals. The receiver lacks filtering to reject out-of-band signals.
Memory Aid
"Receiver overload = can't reject strong signals. Think 'R'eceiver 'O'verload = 'R'eceiver 'O'verwhelmed by strong signals. Lacks filtering to reject out-of-band signals."
Real-World Application
Your neighbor's AM radio picks up your 2-meter FM transmission even though you're on 146 MHz and AM broadcast is around 1 MHz. This happens because your strong signal overloads their receiver's front-end, which lacks sufficient filtering. The solution is to add a filter to their receiver's antenna input, not to change your transmitter settings. Your signal is legal - their receiver needs better filtering.
Key Concepts
Why Other Options Are Wrong
Option B: Incorrect. Microphone gain affects audio level and deviation, not whether broadcast receivers pick up your signal. This is an audio control, not an RF issue.
Option C: Incorrect. Audio amplifier overload affects your transmitted audio quality, not whether other receivers pick up your signal. This is an internal transmitter issue.
Option D: Incorrect. Low deviation would make your signal weaker, not cause interference. The problem is receiver overload from strong signals, not deviation level.
题目解析
The correct answer is A: The receiver is unable to reject strong signals outside the AM or FM band. A broadcast AM or FM radio receiving an amateur radio transmission unintentionally is caused by fundamental overload - the receiver cannot reject strong signals outside its intended band. When a strong amateur signal (even on a different frequency) is near the broadcast receiver, it can overload the receiver's front-end, causing it to receive the signal even though it's outside the AM or FM band. This is a receiver problem, not a transmitter problem. For amateur radio operators, understanding this helps when neighbors report interference - the issue is often their receiver's lack of filtering, not your transmitter's output.
考试技巧
Broadcast receiver picking up amateur signal = receiver overload. Think 'R'eceiver 'O'verload = 'R'eceiver can't 'O'reject strong signals. The receiver lacks filtering to reject out-of-band signals.
记忆口诀
Receiver overload = can't reject strong signals. Think 'R'eceiver 'O'verload = 'R'eceiver 'O'verwhelmed by strong signals. Lacks filtering to reject out-of-band signals.
实际应用示例
Your neighbor's AM radio picks up your 2-meter FM transmission even though you're on 146 MHz and AM broadcast is around 1 MHz. This happens because your strong signal overloads their receiver's front-end, which lacks sufficient filtering. The solution is to add a filter to their receiver's antenna input, not to change your transmitter settings. Your signal is legal - their receiver needs better filtering.
错误选项分析
Option B: Incorrect. Microphone gain affects audio level and deviation, not whether broadcast receivers pick up your signal. This is an audio control, not an RF issue. Option C: Incorrect. Audio amplifier overload affects your transmitted audio quality, not whether other receivers pick up your signal. This is an internal transmitter issue. Option D: Incorrect. Low deviation would make your signal weaker, not cause interference. The problem is receiver overload from strong signals, not deviation level.
知识点
Fundamental overload, Receiver overload, RF interference, Broadcast receiver interference
Verified Content
Question from official FCC Technician Class question pool. Explanation reviewed by licensed amateur radio operators.