Deep Dive: E7C08
The correct answer is B: A helical filter. Which of the following is most frequently used as a band-pass or notch filter in VHF and UHF transceivers is a helical filter. Helical filters are commonly used in VHF/UHF transceivers. For amateur radio operators, this is important for filter design. Understanding this helps when working with transceivers.
Why Other Answers Are Wrong
Option A (Sallen-Key filter): Incorrect. Sallen-Key isn't most frequently used - helical filter is used in VHF/UHF transceivers. Sallen-Key isn't the answer. Option C (Swinging choke filter): Incorrect. Swinging choke isn't most frequently used - helical filter is used in VHF/UHF transceivers. Swinging choke isn't the answer. Option D (Finite impulse response filter): Incorrect. FIR filter isn't most frequently used - helical filter is used in VHF/UHF transceivers. FIR filter isn't the answer.
Exam Tip
Band-pass/notch filter in VHF/UHF transceivers = helical filter. Think 'H'elical 'F'ilter = 'H'igh frequency (VHF/UHF). Helical filters are commonly used in VHF/UHF transceivers. Not Sallen-Key, not swinging choke, not FIR - just helical filter.
Memory Aid
Band-pass/notch filter in VHF/UHF transceivers = helical filter. Think 'H'elical = 'V'HF/'U'HF. Helical filters are commonly used in VHF/UHF transceivers. Important for filter design.
Real-World Example
Band-pass or notch filters in VHF and UHF transceivers: A helical filter is most frequently used. Helical filters provide good performance at VHF/UHF frequencies. This is the filter - helical filter for VHF/UHF transceivers.
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.