Yesterday many stations called 9K2GS. I set KX3 to max processing and started calling signing as QRP. He picked me up from many stations and gave 59. Excellent achievement for KX3. Efficient EQ + proc in KX3 is revolution in QRP radios.
However, he could not copy me later. My battery dropped from 11.2 to 11V (under load), and according to LP100, KX3 reduced power from 10W to 1.5W. Must have been combination of power reduction under lower voltage plus ALC adjustments. The battery is 3S2P 4.4AH Li-Ion. Max 12.6V and smaller and lighter than LiFePO3.
With current firmware, KX3 drops power from 10W to 5 W at 11V. At >11V, KX3 can switch to more efficient winding at 5 W (although the relay clicks at 3W in SSB).
As the primary purpose of KX3 is portable operation, I suggest a more flexible power scheme.
1. Reduce power gradually based on voltage. May be based on lookup table.
2. Whenever the power is set to <=5W, use the more efficient winding. Even though the power can be < 5W at lower voltage.
KX3 is an excellent radio. Played HDSDR with it and it worked very well.
I will write an eham review soon.