[Milsurplus] Need help with ART-13

[Robert Watson]

Meir, Jack, Robert, Ralph, Ray, and Mac,  thanks so much for all the wealth of information.  My power supply is actually three separate supplies mounted on a common chassis.  The 26v, 400v, and 1200v supplies are all solid state.  There is a 12.5 ohm 10 watt shunt resistor on the centertap of the power transformer supplying 1200VDC and is connected to pin 5 of the ART-13 power connector.  The center tap is floating, at least to the point where the shunt resistor is connected to pin 5.
 
The only band I have tried to load up on is 80 meters.  I can watch my wattmeter and adjust the tune and load controls and get a definite peak on output power albeit only about 30 watts carrier.  I have listened to the signal in my 51J4 and it is on frequency.
 
I will loook at the meter circuit.  The unit appears to have not been modified anywhere I can physically observe.
 
Bob, KN4HH