I cracked into one of these and there is an adjustable coil so I am
sure you could bring the output up into a dead frequency of the
broadcast FM band. There is also a BA1401 that is the chip in most of
the FM transmitter kits you see on the internet. I assume you can also
buy that assembled. I played with one for a while and it does have an
adjustable output. I probably still have that around here too.
It is also pretty low power and would not really work out in the yard
either. There is an FM pirate radio web site that tells you how to
ramp up the power but once I found the RCA deal I didn't see the need
to play "come and get me copper" with the FCC..