I'm having an ongoing problem with burning up coax cable feedlines. This has been almost entirely on 6m, where I have been doing the majority of my operating the past few years and primarily during the summer Es season.  I usually run between 500--1000W.  SWR has been very good right up until the moment of failure, which never seems to occur at an opportune time.  Cable does not internally short, so I assume the inner conductor has wandered far enough to send SWR through the roof.  It has been happening every 18--24 months, with the latest cable failure during a meteor scatter run in this weekend's Perseids shower.  I don't trust my cable assembly skills, so have been buying professionally made cable runs from BuryFlex, CableXperts, and recently JEFA Tech, and always a variant of the flexible LMR400.  Stiffer cable would be a substantial pain to install at my station, but I will have to deal with it if this is the solution.  Advice appreciated.  Mike WB2FKO