I have built several U3S and 5 watt PA units over the last few few years and one thing that I have noticed especially when using 10 meters is the single band unit with the LPF in the zero slot has more output than when in the #1 slot on the LPF board unit.
This really doesn't make a lot of sense to me as it is with the same antenna, PSU, etc.
I have tried changing from one amp to the other and still get the same results.
With the single band unit I can achieve 5 watts on 10m and run the amp at 12 vdc and it hardly gets luke warm and with the unit and LPF board I can get a max of 2 watts.
Anyway just wondering if anyone else has experienced this.