Allison KB1GMX notes that if you have a v4 board and experiencing low power output on lower bands (80m and 40m) you may want to check the emitter of Q90 to see if a .01uf or a 470pf or 220PF is there.
There was a change to lower the value from .01 to 470 pf to level the output
power so 80M wasn’t 15-20W when 20m was maybe 8 watts output.
Some have experienced that low bands work very poorly with a 470pF or 220pF capacitor. You may want to increase the capacitor back to 0.01µF or perhaps 1000pf.