[Elecraft] K3 and XV144 strange behaviour

[Giulio Pico - IW3HVB]

I noticed a strange behaviour during the last IARU VHF Contest last 
weekend.....
With our team we managed to have a first field test of the rig.... 
coming for our experience with the K2/xv144 MHz combination the 
expectations were high.
The setup was composed by the K3 and a XV144 transverter, plus a Power 
amplifier, a preamplifier at the antenna (with some 30 mt of 1/2" 
cellflex line) and two stacked 19 elements Log Loop Yagis.
The switching sequence was controled by an external sequencer drived by 
a foot pedal.
On the receiving side the combo was wonderful, the dynamic range allowed 
us to manage very well in the pretty crowded 2 mt band.
But we had some troubles mainly on TX.
Let say that our P.A. needs to be drived with circa 7/10 Watts at 
maximum (depending on the mode, SSB or CW). It's made from 2 x 4CX250B 
in push-pull configuration.
So I tuned the transverter to go from a range of 1 W (with -10 dBm drive 
from the KXV3 module) to a mazimum of 10 W (with 0 dBm of drive).
Things have worked pretty smoothly most of the time, but on a few 
occasions, we noticed a sudden loss of output power from the transverter 
(and from the P.A. of course).
Turning the K3 off and on again the transverter didn't power up. The 
XV144 label on the front panel flashed for a brief moment and then 
stayed off.
Changing band to HF and back again on 144 MHz (TRV1) and the XV144 
module powered up again. Not always on the first try.
Once powered up most of the times the output power was correct, but 
occasionally we had to do the procedure three or four times before 
coming back to normal functioning.

Any clues of the reasons of this behaviour???

73 de Giulio IW3HVB