Two years after KPEN's successful debut, the transmitter was moved to San Bruno Mountain and power increased to 35,000 watts. Then, on August 14, 1964, power was further increased to 125,000 watts, making it the most powerful signal west of the Mississippi River (it was grandfathered in at that power level by the Federal Communications Commission (FCC), which capped stations in that part of the country at 50,000 watts).