Deep Dive: E7E02
The correct answer is D: Produce PM or FM signals by varying a capacitance. What is the function of a reactance modulator is to produce PM or FM signals by varying a capacitance. Reactance modulators vary capacitance (or inductance) to modulate frequency. For amateur radio operators, this is important for modulation. Understanding this helps when working with modulators.
Why Other Answers Are Wrong
Option A: Incorrect. Producing PM or FM by varying resistance isn't correct - reactance modulator varies capacitance. Varying resistance isn't correct. Option B: Incorrect. Producing AM signals by varying inductance isn't correct - reactance modulator produces PM/FM by varying capacitance. AM isn't correct. Option C: Incorrect. Producing AM signals by varying resistance isn't correct - reactance modulator produces PM/FM by varying capacitance. AM isn't correct.
Exam Tip
Reactance modulator function = produce PM or FM signals by varying capacitance. Think 'R'eactance 'M'odulator = 'V'aries 'C'apacitance (PM/FM). Reactance modulators vary capacitance (or inductance) to modulate frequency. Not varying resistance, not AM - just PM/FM by varying capacitance.
Memory Aid
Reactance modulator function = produce PM or FM signals by varying capacitance. Think 'R'eactance 'M'odulator = 'V'aries 'C'apacitance. Reactance modulators vary capacitance (or inductance) to modulate frequency. Important for modulation.
Real-World Example
A reactance modulator: Its function is to produce PM or FM signals by varying a capacitance. By changing the capacitance in the oscillator circuit, the frequency is modulated. This is the function - PM/FM by varying capacitance.
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.