Deep Dive: E7C10
The correct answer is B: A cavity filter. Which of the following filters is used in a 2-meter band repeater duplexer is a cavity filter. Cavity filters are used in repeater duplexers. For amateur radio operators, this is important for repeater design. Understanding this helps when working with repeaters.
Why Other Answers Are Wrong
Option A (Crystal filter): Incorrect. Crystal filter isn't used - cavity filter is used in 2-meter repeater duplexers. Crystal filter isn't the answer. Option C (DSP filter): Incorrect. DSP filter isn't used - cavity filter is used in 2-meter repeater duplexers. DSP filter isn't the answer. Option D (L-C filter): Incorrect. L-C filter isn't used - cavity filter is used in 2-meter repeater duplexers. L-C filter isn't the answer.
Exam Tip
Filter in 2-meter repeater duplexer = cavity filter. Think 'C'avity 'F'ilter = 'C'ommon in 'F'repeater duplexers. Cavity filters are used in repeater duplexers. Not crystal filter, not DSP filter, not L-C filter - just cavity filter.
Memory Aid
Filter in 2-meter repeater duplexer = cavity filter. Think 'C'avity 'F'ilter = 'R'epeater duplexer. Cavity filters are used in repeater duplexers. Important for repeater design.
Real-World Example
A 2-meter band repeater duplexer: A cavity filter is used. Cavity filters provide the high selectivity needed to separate transmit and receive frequencies in a duplexer. This is the filter - cavity filter for repeater duplexers.
Source & Coverage
Question Pool: 2024-2028 Question Pool
Subelement: E7C
Reference: 2024-2028 Question Pool · E7 - Practical Circuits
Key Concepts
Verified Content
Question from the official FCC Extra Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the E7C topic.