Lets say our rippy doo amp is running 5 kv plate AB2 GG. The plate Z = about 12.5K at idle current..Now at "berserko speech", as Rich would say, 1 amp of plate current the plate Z = 3.125k. What's up with the output spectrum??? How do I match to this thing?? What plate Z should I design around??? Near as I can see it varies from >12k to < 3k over the speech envelope!! Dennis