Amateur radio support structures (towers) shall not exceed a height above ground level of 70 feet, unless a conditional use permit has been granted by the City Council. They shall be mounted on the roof of a dwelling or other building or located in the rear yard unless there is not sufficient space to erect them in those locations. They shall be installed in accordance with the instructions furnished by the manufacturer of that tower model. Because of the experimental nature of the amateur radio service, antennas mounted on a tower may be modified and changed at any time so long as the published allowable load on the tower is not exceeded and the structure of the tower remains in accordance with the manufacturer's specifications.