Last week I started to transmit with my new multi-band wspr beacon. Hardware is here:
http://gadgetgangster.com/find-a-project/56?projectnum=257
http://blog.g4ilo.com/2012/01/propeller-takes-to-air.html
This is multi-band multi-mode beacon and now I transmit wspr and opera (http://groups.yahoo.com/group/O_P_E_R_A_/) on 10Mhz, 7Mhz and 3,5 Mhz, RF output power after filter(s) is approximately 11-14 milliwatts, input power ~ 30 mA on 12V DC battery.
Signal from propeller IC PLL is dirty and I decide to not use any amplifier.
Antennas: quarter wave vertical for 30m, quarter wave vertical for 40m, two phased verticals for 40 meters and long wire for 80m.
On 30m I received many reports from EU but noting from DX stations. On 40m with vertical max distance was north EU about 2600km but with two element I have almost every night some report from North America stations. Till now I don't receive any report on 80meters and next days will try with different antenna.
I receive only EU 30m opera reports, nothing on 40 and 80m...

73 to all,
cu

Andrea, 9a3jh

The best amplifier is antenna :-)