What band are you tripping out on?
What is the SWR on the band?
When you are using low power, what is the reflected power coming back?
Are you using an antenna tuner?
If using an antenna tuner, the one in the rig or and external tuner on the antenna side of the LA-1K?
What kind of coax are you using?
Have varmints attacked the coax? ?Very common issue BTW,
Are all of your PL259 connections good?
Has this tripping out situation just started or has it been since day one?
All of these questions may lead you to a solution.
73
Art W1SWL