[1000mp] Driving 3-500Z Amp with Mark V

[frank60]

I have a brand new Mark V and I am trying to drive
a Drake L7 amp and a TL-922A amp but the Mark V
just shuts down and wont put any power out at all.   

I've been driving these two amps with all my other previous
rigs including the Yaesu 920 with no problems.   
I even put both amps into a 2000 watt dummy load and it
still wont drive them.     It just drops down to zero output
power and shuts completely down as I try to drive either 
amp.  

My station grounding is via a large copper plate that is used
as common ground going to a large grounding grid outdoors.  

So this appears to be a problem only related to the Mark V.

Has anyone else had a similar problem? 

W7is@arrl.net