Deep Dive: E7E01
The correct answer is B: Reactance modulation of a local oscillator. Which of the following can be used to generate FM phone signals is reactance modulation of a local oscillator. Reactance modulation varies frequency for FM. For amateur radio operators, this is important for modulation. Understanding this helps when generating FM signals.
Why Other Answers Are Wrong
Option A: Incorrect. Balanced modulation of audio amplifier isn't FM - reactance modulation of oscillator is FM. Balanced modulation isn't FM. Option C: Incorrect. Reactance modulation of final amplifier isn't correct - reactance modulation of local oscillator is FM. Final amplifier isn't correct. Option D: Incorrect. Balanced modulation of local oscillator isn't FM - reactance modulation is FM. Balanced modulation isn't FM.
Exam Tip
Generate FM phone signals = reactance modulation of local oscillator. Think 'F'M = 'F'requency 'M'odulation (reactance modulation). Reactance modulation varies frequency for FM. Not balanced modulation, not final amplifier, not balanced modulation of oscillator - just reactance modulation of local oscillator.
Memory Aid
Generate FM phone signals = reactance modulation of local oscillator. Think 'F'M = 'R'eactance 'M'odulation. Reactance modulation varies frequency for FM. Important for modulation.
Real-World Example
Generating FM phone signals: Reactance modulation of a local oscillator can be used. By varying the reactance in the oscillator circuit, the frequency is modulated. This is the method - reactance modulation of local oscillator.
Source & Coverage
Question Pool: 2024-2028 Question Pool
Subelement: E7E
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 E7E topic.