[Elecraft] How can one shut down a K3 radio remotely?

[Don Wilhelm]

John,

Use the PS cat command - see the K3 Programmer's Reference.
Power on must be external to the K3 - pull pin 8 of the ACC connector 
low with some external device (or press the POWER switch)..

Please note: Even if you ask a question in the subject line, please 
repeat it in the body of your post - IMHO it is more meaningful just to 
make a brief reference in the subject line and ask the question in the text.

73,
Don W3FPR