IMO the best bargain is a used Ameritron AL-811 three tuber with 572B tube upgrade. Amp is usually $400-$450 and three new 572B are under $200. 80 watts in, 800 watts PEP out on 75 meters, a little less on 10 meters. It will run 1000 PEP out with 100 watts drive on 75 meters, but 800 watts is about the same on the receive end. The extra 572B in the four tube model is a waste of a tube, both the 3 or 4 tube Ameritron have the same strong power supply and three tubes does not need neutralization.