Deep Dive: G8B07
The correct answer is B: 416.7 Hz. The frequency deviation for a 12.21 MHz reactance modulated oscillator in a 5 kHz deviation, 146.52 MHz FM phone transmitter is 416.7 Hz. The deviation is reduced by the multiplication ratio: 5 kHz / 12 = 416.7 Hz (since 146.52 / 12.21 ≈ 12). For amateur radio operators, this explains how multipliers affect deviation. Understanding this helps when designing FM transmitters.
Why Other Answers Are Wrong
Option A (101.75 Hz): Incorrect. 101.75 Hz is too low - calculation gives 416.7 Hz, not 101.75 Hz. Calculation error. Option C (5 kHz): Incorrect. 5 kHz is the final deviation, not the oscillator deviation - oscillator deviation is reduced by multiplication ratio. 5 kHz is the output, not input. Option D (60 kHz): Incorrect. 60 kHz is way too high - oscillator deviation is less than final deviation, not more. 60 kHz is too high.
Exam Tip
Oscillator deviation = final deviation / multiplication ratio = 5 kHz / 12 = 416.7 Hz. Think 'O'scillator 'D'eviation = 'O'utput 'D'eviation divided by 'M'ultiplication. Deviation is reduced by multiplication ratio. Not 101.75 Hz, not 5 kHz (final), not 60 kHz - just 416.7 Hz.
Memory Aid
Oscillator deviation = final deviation / multiplication ratio = 416.7 Hz. Think 'O'scillator 'D'eviation = 'O'utput divided by 'M'ultiplication. Deviation is reduced by multiplication ratio. How multipliers affect deviation.
Real-World Example
A 146.52 MHz FM transmitter: Final deviation = 5 kHz, multiplication ratio = 12 (146.52 / 12.21 ≈ 12). Oscillator deviation = 5 kHz / 12 = 416.7 Hz. The reactance modulated oscillator at 12.21 MHz has 416.7 Hz deviation, which is multiplied to 5 kHz at 146.52 MHz. This is how multipliers affect deviation.
Source & Coverage
Question Pool: 2023-2027 Question Pool
Subelement: G8B
Reference: 2023-2027 Question Pool · G8 - Signals and Emissions
Key Concepts
Verified Content
Question from the official FCC General Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the G8B topic.