Thanks to Don, Rick, and Johnny for the suggestions. I had the opportunity to closely inspect the 80 meter antenna today after running a dummy load at the antenna switch and found a carbon trace on an insulator at the feed point. Mystery solved.
73, Bob K5SM On 9/29/2011 7:50 PM, Don Wilhelm wrote: > Bob, > > I suspect a fault in your antenna system that is OK at 100 watts, but > does something "funny" (like perhaps arc over) when 500 (or 250) watts > is applied. > > Does the same thing happen into a dummy load? If so, then it is a > KPA500 problem, but if OK on a dummy load, take a good look at your > antenna system. > > 73, > Don W3FPR > > On 9/29/2011 8:43 PM, Robert Redmon wrote: >> I put my KPA500 on 80 meters for the first time this morning, and it >> faults after several characters. SWR as shown on both the K3 and the >> KPA500 is 1.3:1. I reduced drive to 11w (250w out), and it still does >> it. The first few cw characters, swr looks fine, but if I pause a bit >> and hit the key again, swr jumps above 5:1 and the amp shuts down with a >> "refl hi" fault. If I run the K3 barefoot at 100w, the swr is steady at >> 1.3:1 no matter what I do. Anybody know what is going on? >> >> > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
