You need a PLL somewhere, because the audio signal is encoded in the frequency shift of the carrier (e.g. 98 MHz +/- 150 kHz). Or maybe you were getting a leak

You need a PLL somewhere, because the audio signal is encoded in the frequency shift of the carrier (e.g. 98 MHz +/- 150 kHz). Or maybe you were getting a leak from the audio signal before modulation, e.g. via power lines or something.