[Elecraft] KX3 && KXPA100 - PA Mode Switches Off

[John Overbaugh]

Following up on a note I sent a few weeks ago, my KX3 and KXPA100 are no
longer playing nice together. When I put the KX3 PA Mode to "On," the
KXPA100 switches on, sits for a couple seconds, and switches off.

I have tried:

   1. Checking power supply (it's at a continuous 13.8v at the KX3)
   2. Changing power cables from the supply to the KXPA100 (from one
   anderson-terminated to another)
   3. Changing which cable plugs in at the rear (KX3 on top, Power In on
   top)
   4. Changing cables: bought a new cable set from Elecraft
   5. Changing RJ-45 connectors: swapped in something I've had laying
   around for the factor connector
   6. Wiggling the RJ-45 connector
   7. Changing KXPA100 modes (ATT on/off, amplifier power on/off, etc.

Same behavior every time. Switch PA Mode to "On" and the KXPA perks up.
10-15 sec later, it drops out. While PA Mode is on, the KX3 allows me to
tune up to 100 watts, but immediately drops to 5 when the KXPA drops out.

I can provide a link to a video of the situation for anyone who thinks they
might have an idea.

The only other piece of data that I can think of that might be helpful: I
run my station off of a LiFePo battery under continuous 13v power. Just
before this started, I realized the KXPA was turning on and off and on and
off - the power supply had been switched off and the battery drained to
nearly flat. I don't know how long it had switched like that and I'm
worried it caused damage to the KXPA100, but don't know how to start
troubleshooting that.

Is there anything I may have overlooked, before I reach out to Elecraft
support and ultimately send the KXPA in for testing?