Hi Paul, Right. The PSU should be rated at 13.8V, minimum 25A continuous. A 30A power supply is better. I find that either the IC-PS15 or the IC-PS125 will do fine at 100W CW output. A PSU which is "short of breath" will sag at full load, causing the symptoms Bob described. Cheers for now, 73, Adam VA7OJ/AB4OJ Scanned for viruses by Blue Coat http://www.WinProxy.com/