Many thanks to all of those who responded to my message and shared their experiences and thoughts: Dave WO2X, Mike VA3MW, Bob K4TAX, Jim K9YC, Victor 4X6GP, and Alan N1AL. With a dummy antenna (Cantenna) on 7MHz, and a 1.1:1 match, using 10w drive the KPA-1500 puts out 605w at first, then settles down two seconds later to 384w with 8w reflected power. With 25w drive, the initial output is 1431w, settling down to 1105w after two seconds, with 20w reflected power. So, the fault seems to be in the antenna, not in the amplifier. The same initial power surge occurs on 14MHz using the dummy antenna. I don't know if it originates in the transceiver or the amplifier, but it doesn't have much effect on reflected power except with the defective antenna. Answering some of the questions that were posed, the double bazooka in this case is the high power version from Radiowavz, two years old. A common mode choke from DX Engineering sits between the end of the feed coax and the antenna. Several Mix 31 snap-on chokes from Palomar are on various short coax jumpers in the shack, and the ground system is very good. The double bazookas I use on 80m and 30m work well and are from iacantennas.com. I am ordering a 40m version from them to replace the one that seems to be faulty. I will try to report the result after I install it. Many thanks again to all, 73, Steve K2SN
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