WA2AAU has a article at http://www.mgef.org/amps/presentation/AMLpa6_C.pdf for modifications to the AML Model S80PCSA amplifier. He has a bunch of these amplifiers that he has been selling at conferences for $35 (as I recall). Modifications are easy ... see the article. While it likes higher voltage, I run mine at 13 vdc in the rover and get ~ 35 watts out. 73, Jon W0ZQ