A rough build of a Pal Electronics KW-1 Watt / SWR meter.
SWR portion not modeled.
Watt meter is for HF (CB?) radio.
The switch in the down position sets the range of the meter to a max of 1000 watts.
To provide 1000 watts input, set the AC generator to an amplitude of 316 volts. The amp meter should be at about 200 mA, that would be full scale on the panel meter.
The switch in the up position gives 100 watts full scale.