Deep Dive: E4D09
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.
Why Other Answers 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.
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 Example
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.
Source & Coverage
Question Pool: 2024-2028 Question Pool
Subelement: E4D
Reference: 2024-2028 Question Pool · E4 - Amateur Practices
Key Concepts
Verified Content
Question from the official FCC Extra Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the E4D topic.