Transmit at lower frequencies?

[kuttikutt]

I would need this bady to transmit at lower frequencies. (I'm builing a circuit and need a FM transmitter to do some debugging)

A division by facor 20 would be nice, so the PI can output a 22050Hz 16Bit wav file at adjustable carrier between 450 and 550 kHz (adjustable by 1kHz).

Is it possible to adjust the registers somehow to achieve this?

I tried to enter frequencies below 1Mhz, however - I get the feeling that the PI only transmits the carrier without any modulation...