You are making some very flawed assumptions here. The very fact that both KAT500's are showing the exact same thing should have told you that they are not the likely problem. Having "new coax" doesn't mean a thing since there are several other possibilities ... connectors, the antenna itself (including the ladder line or the connection to it), or even your new coax. All of those could be fine at low power and yet be problematic at higher power. In fact, if the problem showed up shortly after you installed the new coax I'd bet $100 that the amps aren't the source.
Dave AB7E On 7/19/2025 9:35 AM, dave ingebright via Elecraft wrote:
Jim, Thanks for your query. I'm tuning at less than 10W, KPA amp always in STBY. Sometimes the tuner finds a better match at a little more power (25-75 Watts); someone else mentioned that, too. But again, yesterday, it found the solution (Multiband ladder-fed G5RV at 40') 14Mhz, and everything was fine during the first part of the FT8 QSO, and then the tuner went to a high SWR fault for no apparent reason. I reset it, and it was fine for the rest of the operating session. It doesn't matter what band or what power. Remember, I have two of these doing the same thing. I still bet there are a couple of little reed relays with pitted contacts in the auto tuner. I am sure a lot of us have wondered how they get away with using those in a ~500W high-voltage environment. I will call the tech line, but wondered if any of you on this reflector have had this problem //dave WB7ELY
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