At 5 watts input, I get something just "north" of 75 watts out of the
KPA500. At 7 watts input, I get 100 watts out from the KPA500. That's not
a "precise" measurement, but hopefully close enough. That was on 40 meters,
by the way. In any event, without doing the math, that seems pretty close
to the 15 DB gain figure I think they were shooting for. I know that about
28 watts input from the K3 just "tickles" the 500 watt output LED on the
KPA500. That's about where I run it when using the amp.
Looking ahead, at the KX3, 10 watts generates about 150 watts, and 12 watts
gets nearly 175 watts.