[Amps] High Grid Current

[Kelly Jones]

Hi Ampsters...
 
Today I replaced the 3 3CX800s in my LK800 with 3 brand new, never out
of the box 3CPX800s.  I originally thought that one of the old tubes
finally kicked off but now I'm beginning to wonder.
 
The amp still seems to be drawing much more grid current than it should.
For example, with about 10 watts drive I'm seeing about 120 watts out.
However the grid current is reading about 50 mills.  If I increase the
drive level, the output goes up slightly, but the grid current goes up
at a much faster rate.  I'm also seeing the SWR bounce around on the
Mark V meter like the input impedance is changing very quickly.
 
Any suggestions as to why the grid current may be high?  I will do some
further tests, but something doesn't seem right somewhere.
 
73
Kelly - N0VD