Mid 1980s with stand alone cast iron generator/lamp, solid cast iron engine, cast flywheel, plywood base, electrically heated. Reversible on the fly with proper Stevensons linkage.
The G designation, following the modelnumber for plants with generator, didn?t appear until 1992. Up to that point, the Jensen 20 plants carrying a Jensen 15 generator, was know as Jensen 20 - Big Power Plant