I saw a case (with another radio) where the power supply shut down under high VSWR. It turned out that the grounds were pretty hot with r.f. energy (it reminded me of when I used to get a slight r.f. burn when I close-talked my D104 and it touched my upper lip). Making sure you have a good shack ground and putting a current balun on the feed line (at the antenna) should help. 73, Bob, N7XY