I had that thought as well. I was also wondering if the cause was unkeying the amp while the IC7300 was still transmitting. To test that I’m going to manually key the amp and then start & stop FT8 transmissions while the amp is keyed. I also have a wide and receiver and directional coupler that I may be able to capture the TX spectrum from the radio at the instant the FT8 transmission ends…
Sent from the all new AOL app for iOS On Thursday, June 11, 2026, 11:35 AM, Andy Durbin via Elecraft <[email protected]> wrote: I had a problem with high SWR when unkeying a TS-590S used with KAT500 and KPA500. It was a challenging investigation. I found that, due to the failure of an electrolytic capacitor, my TS-590 was emitting a short burst of RF on a completely spurious frequency when it was unkeyed. The failed capacitor changed the rise time of a TX/RX switching signal and resulted in an unintended oscillatory loop. The spurious frequency was way off the frequency to which my antenna was tuned so I received a high SWR indication. I'd suggest you use appropriate tools to examine the frequency of the amplifier RF drive signal for the TX/RX transition. 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 Message delivered to [email protected] ______________________________________________________________ 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 Message delivered to [email protected]
