A fixed high frequency oscillator, variable frequency divider, and low frequency timer are provided to produce a high frequency output pulse group which is terminated at different intervals by both the variable frequency divider and the timer. The characteristics of the frequency divider may be varied to produce a number of modes of generator operation, all of which utilize a single high frequency output. The generator includes circuitry for producing a voltage spike as one of the pulses of each output group with a ratio of peak power to RMS power of at least 10:1 in the cut command group and at least 19:1 in the coagulate command group. The spike reionizes the current path through tissue without excessive tissue destruction due to wasted power. A pair of opto-isolated hand-held switches allow the user to select continuously between two preset modes of operation without risking shock.