Jim Kelley wrote:
Your expectation of obtaining 400 watts from two 100 watt radios hints
at a possible error in your understanding regarding simultaneously
superposing voltages and currents. Just a thought.

Put two 70.7 vdc batteries in series with a 50 ohm load.
Switch in one battery at a time. Each battery will
supply 100 watts. Now switch in both batteries. They
will supply a combined 400 watts. The batteries are
required to supply the extra constructive interference
energy assuming each battery maintains its constant
70.7 vdc voltage output.

This is what has to happen when two coherent RF voltages
are superposed in phase. I just don't think an IC-706
will do that, i.e. it is not a linear device, thus
violating the requirements for superposition. In phase
superposition would require that:

Vtot = V1/_0 deg + V2/_0 deg = |V1|+|V2|

Ptot = P1 + P2 + 2*SQRT(P1*P2)cos(0)

Ptot = 100w + 100w + 2*SQRT(100w*100w) = 400w

Presupposition of linearity of any amateur radio
transmitter without proof is foolish as is the
presupposition that a ten cent resistor or a $10
resistor will gobble up all the reflected energy.
--
73, Cecil http://www.w5dxp.com