This report describes the design of a versatile gimbal structure for use in the West Aperture Room of the Army's Radio Frequency Simulation System (RFSS) for performing RF evaluation measurements of missile radomes and RF seekers. This gimbal is capable of rotating radomes of up to 18 inches in diameter and weighing as much as 50 lbs about fixed RF seeker antennas. The radome motion limit is + or - 40 deg about boresight in both azimuth and elevation. Other elements used are: (1) A sturdy hinged seeker antenna mount that will permit accurate positioning of the seeker antenna when the radome is mounted or removed from the gimbal. (2) A movable cart that can lift the entire assembly off the door frame and carry it out of the way. and (3) A specially designed cart to remove the aperture door and store it while the radome positioner is being used. The radome positioner is controlled by a microprocessor that permits manual operation and the selection of one of several raster scan patterns to ease data taking. Precision speed and position controlling is accomplished by a closed-loop servo approach where the loop is closed via the computer. The positioner provides additional capability to perform antenna pattern measurements using the RFSS array and anechoic chamber and may possibly function as a general purpose gimbal permitting closed-loop tracking of the array by experimental RF seekers. Keywords Gimbal mechanical design; and Electrical controls.