This link will make my various Propeller loving readers happy: Eldon, WA0UWH received a Propeller microcontroller board for Christmas, and decided to try to use it to create a QRSS beacon. With other microcontrollers you generally just program it to generate a keying signal that passes into a FSK input on some other transmitter/oscillator. But Eldon used a unique feature of the Propeller: it can directly synthesize frequencies using an on chip 80Mhz oscillator and a PLL. In theory all you really need to make a QRSS beacon is a low pass filter (which Eldon also created). There are some potential problems (phase noise, temperature stability) but the idea is very cool. Check it out!