All of our products with TTL RS232 3.5 mm jacks use the same pin assignments. Tip is RXD from the radio's perspective, Ring is TXD. Remember that on the KH1 this is also the key jack (DOT is tip, DASH is ring, though these can be reversed in firmware). To use the RS232 interface, set MENU:KEY JACK to RS232. This is what you'd use with a SOTACAT, etc., for FT8.
73, Wayne N6KR On Sat, Feb 7, 2026 at 5:39 AM Matthew Kaufman via Elecraft < [email protected]> wrote: > Someone emailed me direct - my information was for the KH1, NOT the KX2 - > I mistakingly read the email as looking for the KH1 info because of that > first sentence, but your subject is for the KX2. Check the KX2 manual, > page 9, for the KX2 pinout. > > Sorry about that! > > 73 > > -- Matt N3AR > > > On Feb 7, 2026, at 5:16 AM, Matthew Kaufman <[email protected]> > wrote: > > > > I believe that sleeve is ground, ring is TxD, and tip is RxD. Wayne or > someone else will correct me if I'm wrong, I hope. > > > > 73 > > > > -- Matt N3AR > > > >> On Feb 7, 2026, at 2:56 AM, Stefan Jansen via Elecraft < > [email protected]> wrote: > >> > >> Hi Wayne, > >> > >> Maybe you remember me, we had a talk at the Ham Radio Friedrichshafen > in 2025 and I asked you about the morse UI for the KH1. > >> > >> Now I would like to come back with another question about the USB cable > for Elecraft KX2/KX3/KH1. I would like to know how the RS232 signals are > mapped onto the 3.5mm plug. I know that RxD and TxD are on the tip and > first ring. Which one is what, and is TxD and RxD from the computer’s > perspective or from the transceiver’s? > >> > >> Sorry for asking, but I couldn’t find out this in text form in any > documentation. > >> > >> > >> Vy 73 de Stefan, DK7STJ > >> > >> -- > >> Stefan Jansen *** E-Mail: [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] > > > > ______________________________________________________________ > 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, Inc. ______________________________________________________________ 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]
