[Elecraft] Can the K3 make power without activating Key Out?

[Andy Durbin]

"So I guess the correct sequence would be to press TUNE on the KAT500 and then push TUNE on the K3 and the KPA500 would not KEY. Correct? Why not have pushing TUNE on the KAT500 initiate the whole sequence...unkey the KPA, start the TUNE on the K3 and tune?"

That's may not be as perfect a solution as you might think.  While I developing my Kenwood/KAT500/KPA500 controller I found that KAT500 enabled the key line when its internal logic saw the tune sequence had terminated.  That was before TX had completed and there was a large power spike.  KAT500 should not re-enable the key line until it detects RF has gone to zero. (Maybe it works better with full Aux bus integration with a K3).

For me the solution was simply to manage the entire tuning sequence with my controller. One key press and the  rest is automatic.  The sequence is:

Detect tune request
Ensure KAT500 keyline is inhibited
Initiate tune TX and increase tune power to level needed by KAT500
Initiate KAT autotune
Detect end of autotune
Terminate tune TX and reset tune power to low level
Verify TX has terminated
Enable keyline (but only if KPA500 OPER mode is active)

It may sound complicated  but the effort of developing the code is more than paid for by having a completely automatic single button capability.

As a bonus I save the tuning solution that existed before tune initiation so it can be restored if I don't like the new solution.

73,
Andy, k3wyc