[Elecraft] K3 Transmit Timeout for Remote Operation

[Dana Roode K6NR]

I've been using my K3 remote for many years.  I'm using VNC to a
controlling PC to operate the K3 and a variety of other equipment.  I have
relied on an imperfect external solution to protect against runaway
transmission.

I've seen postings to the list over the years about a timeout that
tracks when the PTT is on and triggers TX Inhibit if its on more than a
defined length of time, resetting when PTT goes off.  Does anyone have a
circuit for this to share or other suggestions?  I imagine a 555 timer or
the like with the right interfaces to the K3.  I understand that some of
the Remote Radio interfaces have this built in, but I'm not using them.

  Dana