creeper6530
commented
10 months ago TL;DR: No, you can't. Also, you don't want to, since it would make it more probable for you to get arrested.
No, you can't increase the transmit power on the Pi alone. Since the Pi has quite low maximum output power per pin, there isn't much one can do inside the code. Larger voltage or current would fry the microchips and PCB traces.
You probably could try using an optimized antenna for greater reach, but note that that increases the chance that you'll disrupt someone else. Also, square waves that the Pi transmits have a crapton of harmonics, therefore you will disrupt people outside the FM band as well, which is much larger problem, as those bands might be better monitored and more important, such as military or aviation bands.
But if you want really far reach and do acknowledge that you WILL get into huge trouble, you could maybe use an external booster. Just ensure that you have enough money for a hefty fine that will most probably follow.
tensorkernel
Is it possible to increase transmitting power by editing the code? I have a high speed power adapter for the PI, and would like to try with more power, or is it already the highest it can go?