Jim, I think it could all be done with your Raspberry Pi idea.
The transmit state of the K3 can be indicated by the state of KEYOUT-LP on pin 10 of the ACC connector. Since it is an open drain, you will need a pullup to determine its state. It is grounded during transmit and open circuit otherwise. When it is grounded, start the timer. You will have to decide how long your transmissions will be. Reset the timer with a positive-going transition of the KEYOUT-LP line.
If the timer expires, I would suggest first issuing a Power Off command to the K3 over the RS-232 connection. If that fails, then more drastic action is required - like pulling the plug.
You can power the K3 back on by pin 8 of the ACC connector. See Remote Power On at page 43 of the manual.
73, Don W3FPR On 5/29/2017 11:20 AM, Jim Miller wrote:
In considering remote operation options I'm still struggling with how to implement a kill switch that is foolproof.
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