You can also use a bare raspi (plus a couple passives...) as a 10mW QRP transmit...

Florin_Andrei · on March 7, 2014

You also need a very, very good antenna for that sort of stunt.

QRP is tough. I'm a licensed HAM radio operator and my Tx has a 5 W final stage, so I fit right into the QRP limits. It's tough. You're at the mercy of the ionosphere all the time.

100 W amplifiers are cheap. :)

sbierwagen · on March 7, 2014

Plus he's doing QRSS using WSPR, which transmits at the breakneck pace of 1.46 baud. Supposedly WSPR works down to -28dB.

http://en.wikipedia.org/wiki/WSPR_%28amateur_radio_software%...

adestefan · on March 7, 2014

I use a WSPR transmitter that outputs around 200mW on 20m and am easily heard all over North Americdn and Europe. I've also had two South Pacific reports.

This was into a poorly tuned dipole at 35ft.

kd0amg · on March 7, 2014

You also need a very, very good antenna for that sort of stunt.

For 10mW, sure, but I've done Michigan to France on 5W with a plain old 40m loop 15-20 feet off the ground. In hindsight, I should have tried it on 3W if only to get 1000mi/W on a cloud warmer.