How hard are you driving your 6146's on 75 meters? Those tubes are rated at
75 watts continuous carrier a piece. 90 watts on cw, and since the duty
cycle is so much less on SSB, they can be pushed even harder. If you are
running more than 200 watts on SSB, I want to see that radio. 6146B's are
rated on CW at 120 watts each, and 6146W's go at 150 watts a piece. Their
is no ts520 with the plate supply to do that.