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!
What Frequency?
What Mode?
Weight?
Ive been think of a long duration balloon since the 80’s. Built one around the 8051 derivative in the early 90’s, but too heavy. It did make a good CW weather station beacon.