What emission is produced by a reactance modulator connected to a transmitter RF amplifier stage?
Why A reactance modulator makes a varying capacitance or inductance appear across a tuned circuit, shifting its resonance in step with the audio. When that tuned circuit is in an amplifier stage after the oscillator, the carrier frequency itself is fixed, so the varying tuned circuit shifts the signal's timing instead, producing phase modulation. Phase and frequency modulation are closely related (both are angle modulation), and PM can be converted to equivalent FM by pre-shaping the audio.
Watch out The choice naming frequency modulation, when it appears, describes what the same reactance modulator would produce if it were connected directly to the oscillator; connecting it to a later amplifier stage gives phase modulation instead. Amplitude modulation requires varying the signal's amplitude, which a reactance modulator does not do.
Reactance modulator on the oscillator = FM; on an amplifier stage after it = PM.