Originally Posted by Z1NONLY

Is this an AM or FM radio?

It's been decades since my radio-tech training but the audio volume is a function of the modulation of the carrier frequency. (at least with respect to the audio you are transmitting)

4w is just the carrier's power. I'm guessing that something is happening to the modulation of the signal when you run at 4w. I have never tuned a radio to do this, but I wonder what happens to the audio's amplitude when it's delivered on a clipped AM carrier. -If a radiated carrier Fq even "clips" the same way an audio signal does when produced by an over-driven audio amplifier...

An oscilloscope and a test tone would go a long way to nailing this down. (I'm really curious about the carrier fq at the different power ratings.