[Milsurplus] Need help with ART-13

[Robert Watson]

I have acquired an ART-13 (ATC model) and am having trouble getting it on the air.
My power supply provides 26vdc, 400vdc and 1200vdc.  I powered up the transmitter and the battery meter functrion indicates normal.  In tune mode and using manual channel, I see appropraite amount of grid current when the test switch is operated.  When I place the meter switch in the plate position, the meter immediately pegs off scale to the left.  If I operate the test switch, no change in the reading.  My power meter indicates that approximately 30 watts of carrier is present at the transmitter output and the antenna current meter does show  a low value.  No increase in output power no matter where I position the tune and load controls. I am able to adjujst frequency OK. Hopefully, I am overlooking something.  
 
I would appreciate any suggestions for troubleshooting.
 
Many thanks,.
Bob, KN4HH