What is the stage in a VHF FM transmitter that generates a harmonic of a lower frequency signal to reach the desired operating frequency?
The correct answer is D: Multiplier. The stage in a VHF FM transmitter that generates a harmonic of a lower frequency signal to reach the desired operating frequency is a multiplier. Multipliers multiply the frequency (e.g., 2×, 3×) to reach higher frequencies. For amateur radio operators, this is how VHF transmitters work. Understanding this helps when designing transmitters.
Exam Tip
VHF FM transmitter harmonic generation = multiplier. Think 'M'ultiplier = 'M'ultiplies frequency to reach 'M'uch higher frequencies. Multipliers multiply frequency (2×, 3×) to reach desired operating frequency. Not mixer, not reactance modulator, not balanced converter - just multiplier.
Memory Aid
"VHF FM transmitter harmonic generation = multiplier. Think 'M'ultiplier = 'M'ultiplies frequency. Multipliers multiply frequency (2×, 3×) to reach desired operating frequency. Used to reach VHF from lower frequencies."
Real-World Application
A VHF FM transmitter: A 12.21 MHz oscillator feeds a multiplier (e.g., 12× multiplier). The multiplier generates harmonics, producing 146.52 MHz (12.21 × 12 = 146.52). Multipliers are used to reach VHF frequencies from lower-frequency oscillators. This is how VHF transmitters generate their operating frequency.
Key Concepts
Why Other Options Are Wrong
Option A (Mixer): Incorrect. Mixers combine frequencies (sum/difference), they don't multiply to generate harmonics - multipliers multiply frequency. Mixers are different.
Option B (Reactance modulator): Incorrect. Reactance modulators vary phase for modulation, they don't multiply frequency - multipliers multiply frequency. Reactance modulators are different.
Option C (Balanced converter): Incorrect. Balanced converters are for frequency conversion, not multiplication - multipliers multiply frequency. Balanced converters are different.
题目解析
The correct answer is D: Multiplier. The stage in a VHF FM transmitter that generates a harmonic of a lower frequency signal to reach the desired operating frequency is a multiplier. Multipliers multiply the frequency (e.g., 2×, 3×) to reach higher frequencies. For amateur radio operators, this is how VHF transmitters work. Understanding this helps when designing transmitters.
考试技巧
VHF FM transmitter harmonic generation = multiplier. Think 'M'ultiplier = 'M'ultiplies frequency to reach 'M'uch higher frequencies. Multipliers multiply frequency (2×, 3×) to reach desired operating frequency. Not mixer, not reactance modulator, not balanced converter - just multiplier.
记忆口诀
VHF FM transmitter harmonic generation = multiplier. Think 'M'ultiplier = 'M'ultiplies frequency. Multipliers multiply frequency (2×, 3×) to reach desired operating frequency. Used to reach VHF from lower frequencies.
实际应用示例
A VHF FM transmitter: A 12.21 MHz oscillator feeds a multiplier (e.g., 12× multiplier). The multiplier generates harmonics, producing 146.52 MHz (12.21 × 12 = 146.52). Multipliers are used to reach VHF frequencies from lower-frequency oscillators. This is how VHF transmitters generate their operating frequency.
错误选项分析
Option A (Mixer): Incorrect. Mixers combine frequencies (sum/difference), they don't multiply to generate harmonics - multipliers multiply frequency. Mixers are different. Option B (Reactance modulator): Incorrect. Reactance modulators vary phase for modulation, they don't multiply frequency - multipliers multiply frequency. Reactance modulators are different. Option C (Balanced converter): Incorrect. Balanced converters are for frequency conversion, not multiplication - multipliers multiply frequency. Balanced converters are different.
知识点
VHF FM transmitter, Multiplier, Harmonic generation, Frequency multiplication
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.