Courtesy of Bill Meara over at SolderSmoke, check out this link to the HF Beacon for MIT Atlantic Balloon Program. It’s a pretty simple 1.5w transmitter for 30m that could be built for about $25. It’s heart is a 74HC540 octal inverter chip, and uses two 2n7000 transistors. Very neat!
This is the greatest thing I’ve seen on youtube in at least a few hours.