The AN/SPS-33 was a vertical, 3-dimensional target-tracking radar developed by the firm Hughes for the American Navy. It operated in combination with the AN/SPS-32 to form the SCANFAR system. The AN/SPS-33 was phased array and was frequency scanned in elevation and phase scanned in azimuth. The AN/SPS-33 had a maximum range of 250 nautical miles. It was unreliable and consumed a lot of power and it was built with vacuum tubes.