Please tell us ho you have the K3, KPA500 and KAT500 connected. I have to assume there is a computer in the mix. The K3 cannot talk to the KPA500 to tell is to shut off, nor can it cause the KPA500 to power up. The same is true for the KAT500, although the KAT can power up on its own when power is applied. A computer or other “intelligent” device is needed to tell the KPA and KAT to power up. In the case of the KPA500, there are two ways to remotely power it up - one is to momentarily ground the power line in the AUX IO connector. This signal cannot be tied to the K3’s power signal because of differences in voltage levels. Connecting them will probably be a good reason to send the KPA back for repairs. The second method is to send a “P” (just the P, no quotes needed) to the KPA500 when it is off (using the serial port). After it powers up, you can shut it off by sending the “^ON;” command to the KPA500. See the KAT500 serial command reference for info on commands specific to it.
And again, the K3 does not send data to the KPA500. The Auxbus is strictly send-only from the KPA500. The only signals that go from the K3 to the KPA are the band signals and PTT. Note that the KPA1500 and KPA500 communicate differently - I don’t have an answer for Jim on his situation. Second, please trim your list emails when replying to digests, and follow the request to change the subject line. It cuts down on the amount of stuff we have to look through, and tells us which of the message you are replying to. 73, Jack W6FB > On Jun 27, 2026, at 12:00 PM, Joseph Koester via Elecraft > <[email protected]> wrote: > > I have a similar issue with my K3 and my KPA500. I cannot turn the amp off. > I can turn the tuner off but not the amplifier. > > Joe/W4NSA > > On Sat, Jun 27, 2026, 11:01 <[email protected]> wrote: > >> Send Elecraft mailing list submissions to >> [email protected] >> >> To subscribe or unsubscribe via the World Wide Web, visit >> http://mailman.qth.net/mailman/listinfo/elecraft >> or, via email, send a message with subject or body 'help' to >> [email protected] >> >> You can reach the person managing the list at >> [email protected] >> >> When replying, please edit your Subject line so it is more specific >> than "Re: Contents of Elecraft digest..." >> >> >> Today's Topics: >> >> 1. K4/KPA500 macro question (Jim Rhodes) >> 2. KX3 Passband, Pitch, and APF (paul somlo) >> >> >> ---------------------------------------------------------------------- >> >> Message: 1 >> Date: Sat, 27 Jun 2026 00:17:07 -0500 >> From: Jim Rhodes <[email protected]> >> To: [email protected] >> Subject: [Elecraft] K4/KPA500 macro question >> Message-ID: >> <CALhxr4ZyaBLACkEM_3O-1iwJyWgW+wgJWKEWWpQDrFbZMQLz= >> [email protected]> >> Content-Type: text/plain; charset="UTF-8" >> >> I am trying to set up macros to turn the KPA500 on and off. I seem to have >> them entered correctly in the K4D and in the KPA500 app. But the app will >> turn the amp on but not off. The K4 will turn it off but not on. Object >> is to get it set up for use with the K4/0. Does anyone how I messed those >> up? >> >> Jim K0XU >> [email protected] >> >> >> ------------------------------ >> >> Message: 2 >> Date: Sat, 27 Jun 2026 05:30:12 +0000 (UTC) >> From: paul somlo <[email protected]> >> To: "[email protected]" <[email protected]> >> Subject: [Elecraft] KX3 Passband, Pitch, and APF >> Message-ID: <[email protected]> >> Content-Type: text/plain; charset=UTF-8 >> >> When I turn on "pitch", does the passband coincide with the signal being >> centered between right and left?? And does the audio peaking filter >> passband coincide with the regular passband? >> Paulwb2eiu >> >> ------------------------------ >> >> _______________________________________________ >> Elecraft mailing list >> Post to: [email protected] >> http://mailman.qth.net/mailman/listinfo/elecraft >> You must be a subscriber to post. >> Elecraft web page: http://www.elecraft.com >> >> End of Elecraft Digest, Vol 266, Issue 17 >> ***************************************** >> > ______________________________________________________________ > 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]
