[Elecraft] KAT100 - confused on R3 and R4 adjustment

[tlogan7@cox.net]

When I set the K2 to 5 watts, I then adjust R4 so that the analog meter
reads the proper voltage.  I then change the K2 to 10 watts and again adjust
R4 to get the proper voltage; then repeat the sequence for 20 watts.  This
makes no sense to me, because obviously when you adjust the power back down
to 5 watts and check the voltage, the voltage will be different than the
original target voltage because you just finished adjusting R4 for two other
power levels. What am I missing?
73/Tim NZ7C