|If you could change the Firmware to broadcast in AM it would not work because all of the client software is written for FM. Also, AM sucks. It is susceptible to EMF which is given off by just about every thing electrical. This is why your AM radio sounds so bad in an electrical storm. |
That aside, there are signal boosters and directional antennas that will improve the distance. Be careful though, if your transmitter is to powerful you may have to get an FCC license.