KPA500 TX with second radio SOLVED
Posted by
ANDY DURBIN on
Feb 07, 2021; 1:33am
URL: http://elecraft.85.s1.nabble.com/KPA500-TX-tp7668050p7668089.html
"Chuck keeps providing riddles for behavior that is a bit different than what I expected. The original K3 with the KIO3 board exhibits exactly the behavior I outlined previously. A K3S or K3 with the KIO3B interface behaves the way Chuck describes. A look at the KIO3B schematic reveals why - it has series connected diodes in the band pull-ups so that when the main Vcc drops at power-off, the band lines are disconnected from the power rail. Thus the pull-ups inside the KPA500 take over and it sees the magic 1111 pattern indicating that no band is connected."
Perhaps I'm a bit perverse but that provided some amusement.
73,
Andy, k3wyc
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