Total posts : 45366
… the Hamilton Rangemaster is probably the best transmitter available that will get you the most range. The ChezRadio Procaster is a close second. …
Note that Part 15 AM “range” depends not just on the transmitter design/performance and its settings.
It also depends on the physical configuration of the transmit antenna system, earth conductivity at/near the transmit site, signals from co- and adjacent-channel stations, ambient r-f noise levels at the receive location, the performance of the AM receiver+antenna, and the tolerance of the listener to the noise/interference levels in the audio they hear.