Deep Dive: G8A04
The correct answer is B: Phase modulation. The emission produced by a reactance modulator connected to a transmitter RF amplifier stage is phase modulation. Reactance modulators vary the phase of the oscillator, producing phase modulation. For amateur radio operators, this is how phase modulation is generated. Understanding this helps when designing modulators.
Why Other Answers Are Wrong
Option A (Multiplex modulation): Incorrect. Reactance modulators don't produce multiplex modulation - they produce phase modulation. Multiplex is different. Option C (Amplitude modulation): Incorrect. Reactance modulators don't produce amplitude modulation - they vary phase, not amplitude. AM is different. Option D (Pulse modulation): Incorrect. Reactance modulators don't produce pulse modulation - they produce continuous phase modulation, not pulses. Pulse modulation is different.
Exam Tip
Reactance modulator output = phase modulation. Think 'R'eactance 'M'odulator = 'R'egulates 'M'odulation by varying 'P'hase. Reactance modulators vary oscillator phase, producing phase modulation. Not multiplex, not AM, not pulse - just phase modulation.
Memory Aid
Reactance modulator output = phase modulation. Think 'R'eactance 'M'odulator = 'P'hase 'M'odulation. Reactance modulators vary oscillator phase, producing phase modulation. Standard phase modulation method.
Real-World Example
A reactance modulator: It varies the reactance (capacitance or inductance) in the oscillator circuit, which changes the oscillator's phase. This phase variation produces phase modulation. Reactance modulators are used to generate phase modulation in transmitters. This is how phase modulation is created.
Source & Coverage
Question Pool: 2023-2027 Question Pool
Subelement: G8A
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 G8A topic.