Open the bottom and at back, there is the main board. At the right bottom is the option for the filters. Close to it - is R1707. This adjust the TX Power. Next to it is R1730. This adjusts the AM carrier.
Adjust R1707 for what you want up to about 200 watts. It will give more but that is at saturation point of the device. Adjust R1730 for the AM carrier for about 40 or 50 watts only. This mod is only in testing and I cannot stress more to be carefull and keep it COOL.