From Wayne N6KR on QRP-L this morning:
The latest KX2 field-test firmware allows power output to be set as high as 12 watts on 80 through 20 meters. (Max out is still 10 watts on 17-10 meters.) Supply voltage must be 12.8 V or higher on key-down. ~14 V supply recommended.
Yes, this is only about 1 dB, but it did help me snag XF1IM this morning on 20 CW.
We consider the change experimental at this point. Not all KX2s are guaranteed to hit 12 W on all of these bands, and this level is recommended for low duty-cycle use, i.e. hunt/pounce.
If you’d like to give it a try, please email me directly. (Editor's note: firstname.lastname@example.org)
So there you have it from The Man, himself!
72 de Larry W2LJ
QRP - When you care to send the very least!