NBFM for transforming a Raspberry PI into a ham radio FM transmitter
Raspberry PI as RF Signal Generator
The Raspberry PI can be turned into a performant RF signal generator without modifications, just using the proper software.
nbfm by IK1PLD is a small program useful to transmit audio information via a frequency modulated RF carrier.
By setting the deviation parameter to zero, it performs like a continuous wave signal generator, in the range 123 kHz - 250 MHz.
Be careful laws may restric radio frequency transmission in your Country.