"Have you considered that there may be something in your antenna system that is heating up or otherwise changing with the 1500 watts power? The first thing I would suspect is a balun that is heating, or a connector that is not quite tight enough."
After years in lab and flight test I came to appreciate the value of good instrumentation. The data below is a case of SWR run-away believed to be caused by heating of a mix 31 choke when an antenna matched for 160 m was used on 80m. The rapid but progressive rise in SWR is very different from what would be expected for an arc-over event. This data log shows parameters reported by my KAT500. The final two events are the KAT500 faulting and opening the KPA500 key line. 2019-02-21 06:56:02 New VSWR - VSWR 1.06; 2019-02-21 06:56:02 New VSWR - VSWR 1.00; 2019-02-21 06:56:02 New VSWR - VSWR 1.08; 2019-02-21 06:56:02 New VSWR - VSWR 1.07; 2019-02-21 06:56:03 New VSWR - VSWR 1.05; 2019-02-21 06:56:03 New VSWR - VSWR 1.08; 2019-02-21 06:56:03 New VSWR - VSWR 1.15; 2019-02-21 06:56:05 New VSWR - VSWR 1.19; 2019-02-21 06:56:05 New VSWR - VSWR 1.25; 2019-02-21 06:56:05 New VSWR - VSWR 1.30; 2019-02-21 06:56:05 New VSWR - VSWR 1.38; 2019-02-21 06:56:05 New VSWR - VSWR 1.44; 2019-02-21 06:56:05 New VSWR - VSWR 1.49; 2019-02-21 06:56:06 New VSWR - VSWR 1.58; 2019-02-21 06:56:06 New VSWR - VSWR 1.72; 2019-02-21 06:56:06 New VSWR - VSWR 1.85; 2019-02-21 06:56:06 New VSWR - VSWR 1.90; 2019-02-21 06:56:07 New VSWR - VSWR 2.00; 2019-02-21 06:56:07 New FLT - FLT4; 2019-02-21 06:56:07 New AMPI - AMPI1; 73, Andy, k3wyc ______________________________________________________________ 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
