You can learn a lot about the hardware used over at http://qrp-labs.com/lightaprs.html http://qrp-labs.com/lightaprs.html Of course he sells stuff to do it, b

You can learn a lot about the hardware used over at http://qrp-labs.com/lightaprs.html http://qrp-labs.com/lightaprs.html Of course he sells stuff to do it, but there are many balloon flights documented on that site too. Some of them have circumnavigated the Earth more than once!