Following the Ocean Floater and the many balloons that utilize this amazing and inexpensive device added further inspiration as did the news that Hans G0UPL is now developing an extremely lightweight transmitter designed for high altitude balloon flights.
At present my U3S is only in its larval stage. I will soon add additional bands (15m only for now) and the automatic band-switching board, a 5V internal converter and a detachable configuration for the GPS receiver that feeds time, grid and freq cal data to the U3S.
|GPS receiver - U3S - wattmeter showing 100mW out|
This is quite a lot of kit for the money - $33 if you don't need the aluminum/aluminium housing ($22) or GPS receiver ($23). For that, you get a transmitter that operates more modes than Kim Kardashian with a Kama Sutra.
Maximum output with only 1 (of three possible) transistor is 250 mW but I've turned mine down to 100 mW.
Initial reports on 15m at this late hour for that presently-handicapped band are proof positive that it works FB and I could almost say that this is a good kit even for a first-time builder. There are no SMD parts and the overall parts count is quite low.
Now to wind those toroids for the other band filters...