[Elecraft] K3 not transmitting anymore

[Ron D'Eau Claire]

Glad to hear it was such an easy fix, Maarten! But you do bring up an issue
that has appeared on the reflector before: the K3 *wants* an orderly
shutdown sequence to avoid unusual and troublesome issues.

An orderly shutdown requires the POWER button be pressed on the K3 before
the power supply is shut down. 

One may be able to shut off the K3 by shutting off the power supply many
times, perhaps hundreds of times, without problem, but there's always a
chance. Indeed, before I understood the situation, I did just that without
incident literally hundreds of times while working on the documentation.
It's easy to forget that radios like the K3 are more "computer" than "radio"
- at least as many of us know "radios", Hi!

The issue is whether the MCU is writing anything to memory at the moment of
power loss. If a data write sequence happens to be underway when power is
removed, there will be a data loss that may cause a wide range of symptoms.
That never happens when the POWER button is used. When you press the POWER
button, any processes that need completion are finished automatically before
the K3 shuts down. 

IIRC, the recovery from a 'scrambled' K3 caused by suddenly removing the
supply power was to do a full reloading of the firmware. I don't recall
whether anyone had to reset the K3 and start over, but that's not a big
issue if you've saved your configuration. 

Ron AC7AC