I have worked on a good number of power amplifiers, most are broadband. The load Z for max output power from all of them is never 50 ohms and if it is it is by chance. All of them are designed to supply a specified power into 50 ohms and into a specified SWR (sometimes up the 3:1 but mostly limited to 2:1) but they can pump out a lot power above the specification into some non-50 ohm loads if the power control loop is not closed. Who knows exactly what load the final device sees when it goes thru output filters and t/r switching. (in the mil and other radio services I bet none of the transmitters run without a power control loop. I never checked my ham band transceiver to see how its power is controlled) When I measured return loss and transmatch output current, I used a good 50 ohm source impedance device (not a power amplifier but a good leveled sig gen and with good RL bridge). What Cecil brought up is not related to what the PA can pump out.....at least I don't think so at the moment If you want to see what the Z is for max output is for you transmitter, re-run the test and then measure the Z looking into the tranmatch. Should be the conjugate of what the transmitter's output Z is for max output...correct?