What is the purpose of the preselector in a communications receiver?
The correct answer is C: To increase the rejection of signals outside the band being received. What is the purpose of the preselector in a communications receiver is to increase the rejection of signals outside the band being received. Preselectors filter out-of-band signals. For amateur radio operators, this is important for receiver performance. Understanding this helps when using preselectors.
Exam Tip
Preselector purpose = increase rejection of signals outside band being received. Think 'P'reselector = 'P'revents 'O'ut-of-'B'and signals. Preselectors filter out-of-band signals. Not frequency storage, not broadband attenuation, not device selection - just out-of-band rejection.
Memory Aid
"Preselector purpose = increase rejection of signals outside band being received. Think 'P'reselector = 'O'ut-of-'B'and rejection. Preselectors filter out-of-band signals. Important for receiver performance."
Real-World Application
The preselector in a communications receiver: Its purpose is to increase the rejection of signals outside the band being received. The preselector filters out unwanted frequencies before they enter the receiver, reducing interference. This is the purpose - out-of-band rejection.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Storing frequencies that are often used isn't the purpose - preselectors filter out-of-band signals. Frequency storage isn't the purpose.
Option B: Incorrect. Providing broadband attenuation before first RF stage isn't the purpose - preselectors filter out-of-band signals. Broadband attenuation isn't the purpose.
Option D: Incorrect. Allowing selection of optimum RF amplifier device isn't the purpose - preselectors filter out-of-band signals. Device selection isn't the purpose.
题目解析
The correct answer is C: To increase the rejection of signals outside the band being received. What is the purpose of the preselector in a communications receiver is to increase the rejection of signals outside the band being received. Preselectors filter out-of-band signals. For amateur radio operators, this is important for receiver performance. Understanding this helps when using preselectors.
考试技巧
Preselector purpose = increase rejection of signals outside band being received. Think 'P'reselector = 'P'revents 'O'ut-of-'B'and signals. Preselectors filter out-of-band signals. Not frequency storage, not broadband attenuation, not device selection - just out-of-band rejection.
记忆口诀
Preselector purpose = increase rejection of signals outside band being received. Think 'P'reselector = 'O'ut-of-'B'and rejection. Preselectors filter out-of-band signals. Important for receiver performance.
实际应用示例
The preselector in a communications receiver: Its purpose is to increase the rejection of signals outside the band being received. The preselector filters out unwanted frequencies before they enter the receiver, reducing interference. This is the purpose - out-of-band rejection.
错误选项分析
Option A: Incorrect. Storing frequencies that are often used isn't the purpose - preselectors filter out-of-band signals. Frequency storage isn't the purpose. Option B: Incorrect. Providing broadband attenuation before first RF stage isn't the purpose - preselectors filter out-of-band signals. Broadband attenuation isn't the purpose. Option D: Incorrect. Allowing selection of optimum RF amplifier device isn't the purpose - preselectors filter out-of-band signals. Device selection isn't the purpose.
知识点
Preselector, Communications receiver, Increase rejection, Signals outside band being received
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.