Topband: Inverted L SWR Jumps ???

[Jeff Woods]

"The inverted L loads just fine to about 700 watts and then causes the Alpha amp to fault out. I think I am getting a sudden change in antenna impedance. The antenna is fed through a 5 KW rated choke balun. The feed line exits the base between radials."

Remove the balun.  It's not doing anything for your and is a potential source of loss and problems.  Coaxial cable is unbalanced, as is a ground-fed inverted L. No need for a balun.  


Check all your connections - make sure they're tight and well soldered or clamped.  You're pushing a lot of RF current through them and a marginal connection will generate much heat and expand.  


-Jeff
W0ODS