Deep Dive: T7B07
The correct answer is D: Installing a band-reject filter. A band-reject filter (also called a notch filter) can reduce overload of a VHF transceiver by a nearby commercial FM station. The filter is installed in the receive path and blocks the strong commercial FM signal (typically 88-108 MHz) while passing your amateur VHF signals (144-148 MHz). This prevents the strong commercial signal from overloading your receiver's front-end. For amateur radio operators, band-reject filters are essential when operating near commercial FM broadcast towers, which can cause severe receiver overload and make it impossible to receive weak amateur signals.
Why Other Answers Are Wrong
Option A: Incorrect. Installing an RF preamplifier would amplify the commercial FM signal along with your desired signals, making the overload worse, not better. Option B: Incorrect. Double-shielded cable reduces RF pickup on cables but doesn't prevent a strong signal from overloading the receiver through the antenna. Option C: Incorrect. Bypass capacitors on microphone cables prevent RF feedback in audio circuits but don't prevent receiver overload from strong signals.
Exam Tip
Commercial FM overload = band-reject filter. Think 'B'and-'R'eject 'F'ilter = 'B'locks 'R'adio 'F'requency interference. It blocks the interfering frequency while passing desired signals. Preamplifiers make it worse.
Memory Aid
Band-reject filter = blocks interfering frequency. Think 'B'and-'R'eject = 'B'locks 'R'adio interference. Filters out the unwanted frequency while passing desired signals.
Real-World Example
A commercial FM station on 100.5 MHz is overloading your 2-meter receiver, making it impossible to hear weak amateur signals. Installing a band-reject filter tuned to 88-108 MHz in your receive path blocks the commercial FM signal while passing your 144-148 MHz amateur signals. This allows your receiver to function normally despite the nearby strong commercial signal.
Source & Coverage
Question Pool: 2022-2026 Question Pool
Subelement: T7B
Reference: 2022-2026 Question Pool · T7 - Practical circuits
Key Concepts
Verified Content
Question from the official FCC Technician Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the T7B topic.