As far as I can tell from looking at the drivers, the transmitter is Si4713. https://www.silabs.com/Support%20Doc...2-13_short.pdf The part is capable of transmitting from 76 to 108 MHz, but probably has a software limitation to keep it legal. Similarly, given the last paragraph in the left column, it's likely that the output power can be increased from the present level, but again may be software limited.