The RS-232 thread comes coincidentally at a time when I have just experienced an RS-232 "gotcha."

If you own a Palstar AT-AUTO you need to remember that the RS-232 cable (null modem) originally supplied with the tuner is cross-wired (pin 2 to pin 3, and pin 3 to pin 2).  This is the correct wiring that allows the tuner to follow frequency excursions by the K3.

Recently I returned my K3 (sn 21) to Watsonville for hardware upgrades that included replacing the KIO3A board with the new KIO3B board (now standard on the K3S).  However, this new board no longer utilizes a DB-9 connector for RS-232 functions, but instead uses a female RJ-45 socket for RS-232 functions.  This now renders obsolete the original DB9-equipped cable that came with the AT-AUTO.  Fortunately, Elecraft includes with the upgraded KIO3B board a pre-wired 30-inch RS-232 cable.  This cable has an RJ-45 plug on one end and a DE9S plug on the other end.  Unfortunately, this cable is wired straight-through . . . no cross-wiring . . . which means no QSY following by the Palstar.

After spending more time than I care to admit in testing cable continuity, serial baud settings, and configuration menus in both the K3 and the Palstar, I suddenly tumbled to the fact that the Palstar cable is cross-wired while the Elecraft cable is not.

Home-brewing a new cable with the proper wiring now permits the AT-AUTO to follow band and frequency changes in the K3. Unfortunately, the Elecraft cable uses molded connectors which prevented an easy and quick fix.

Just a tip for those who own either the original Palstar AT-AUTO or the newer HF-AUTO (which I presume is wired the same), or for anyone using RS-232 peripheral devices who want to upgrade to the new KIO3B board.  Those pin-outs in the manuals are there for a reason!

73,

Kent Trimble, K9ZTV
Jefferson City, Missouri

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