[Elecraft] KX3 reboot only on JT modes?

[rich hurd WC3T]

Okay, here's an odd one and I couldn't find any suggestions in the archives
or using Google-fu.

I can run any mode with my KX3/PX3/KXPA100 station with no incident except
for JT modes; using WSJT-X, I will complete a Tx cycle and randomly the KX3
will bounce (power off/power on.)
9 times out of 10, I'm operating at 3W.   I'll sometimes bump to 5.  To
test this, I have also bumped it to 11 watts to kick the amp in and I get
the same reaction; that is, sometimes (but not always) the station just
decides it's had enough and the power bounces.   Power supply is a Samlex
SEC-1223.

ALC is within tolerance, MIC BTN is off, it's operating in DATA A and VOX
is set on.

I'm kind of running out of things to try.  Any thoughts?

BTW, I am getting out there; PSKReporter shows activity so I'm putting the
fire in the wire.  It's just this power thing is flakey.

-- 
73 (or 72 for the QRP folks),
Rich Hurd / WC3T
Northampton County RACES
EPA-ARRL Public Information Officer for Scouting
Latitude: 40.761621 Longitude: -75.288988  Grid: *FN20is*
40°45.68' N 75°17.33' W