Greetings!
This Raspberry Pi thing is too good to ignore. It only needs a small broadband output amp of 1-5 watts, and simple transmatch which can serve also as a high-pass filter, and we're on 100KHz to 144MHz. The Pi board has plenty of I/O that can be used to operate a transmatch I am sure.
How hard could it be? If the transmatch was automatic, there could be a plug-and-play beacon - just add longwire antenna.