Bill: The intent is that you can keep the tuner in auto or perhaps better manual. When you tune initially at 3550 and press ATU tune, the tune search quickly finds the ATU bypassed setting is appropriate because the SWR when L and C are bypassed is 1.2 or better. It saves "bypassed" as the preferred tuner solution for that frequency,. Thereafter when you transmit on 3550 in Mode Auto or Manual, the ATU loads the bypassed tuner solution.
Further up the band the ATU finds that a little L and C helps, so when you first tune there, the ATU stores that solution for that frequency. Without changing mode, the ATU can load the appropriate tuner setting, which may be bypassed on 3550. In mode manual and auto the bypassed tuner solution is exactly the same relay settings as you get with mode bypass; all the inductors and capacitor relays are bypassed. There is no ATU loss advantage to being in mode bypass vs mode manual or auto and the bypassed tuner solution. To answer you other question, in mode bypass the ATU won't retune. If the SWR exceeds a configurable threshold, it can interrupt your amp. That is the VSWR threshold for amp interrupt. I think we default it high, but you can set it to 3 or 5 to 1. Some amps are touchy about having the key line changed with RF flowing. But to avoid having to remember, consider letting the ATU tune at 3550. The KAT500 Utility operate page will help you understand the tuner solution found. The bypass VSWR shown is the VSWR measured with the ATU bypassed, the SWR of your antenna without correction. The full search tune algorithm tries "Bypassed" as its very first try. If you would prefer a different SWR threshold for the bypassed tune solution, it can be changed in Edit Configuration, VSWR threshold, bypass SWR. I think I have mine at 1.5 or so. Some people like to see really low SWR, some prefer fewer changes as long as the amp stays happy. 73 de Dick, K6KR > On Nov 14, 2013, at 20:39, bill.va...@gmail.com wrote: > > will the interrupt feature work even when the tuner is in the bypass mode? > > For example: at 3.550 I don't need a tuner, so I put it into bypass. I then > move to 3.750 but forget to reset the tuner to auto. will the KPA500 be > protected with the key-line interrupt even when I am in bypass mode? > > Thanks, I looked in the manuals but didn't find a definitive answer. > > Bill, VA3OL > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
