Frequency divider on FM transmitter

I have an FM transmitter with integrated PLL and VCO synth. I want to use the transmitter on a lower frequency. Is there any easy way to divide the signal by 2?

I have another chip that has a built in divider that outputs a square wave. If i use the divider function of this chip and modulate the vtune pin, will the modulation on the divided frequency be distorted or will it sound the same as the fundamental?

What do you want to do ?

Make frequeny deviation half without changing carrier frequency ?

Make instantaneous frequency half ?

I want the deviation to stay the same. I just want the carrier frequency in half.
It is an FM transmitter chip, but I want to use it at 50mhz. Will it distort the audio?

It depends on how the modulation is applied to the carrier. Most systems directly modulate the VCO and that makes things difficult because the modulation will also be divided. If the PLL is mixed with another local oscillator and the modulation is applied there, you can divide the original frequency by some figure and it will then work. The down side to that is the division ratio isn't 2 because you are only changing part of the final frequency.

What is the 'integrated PLL and VCO' device? It may be possible to simply re-tune it to a different frequency if you can sacrifice multi-frequency operation.

Brian.