and minus direction from the local control/motor drive controller at least once every three months during antenna down time. Check the mechanical limit switches provided at the end points stop antenna and feed movement, and limit travel to prevent structural interference and damage. Check the mechanical limit switches for corrosion and water entry and the arm on each feed limit switch for free movement without binding. Be cer- tain both feed rotation limit switch arms are not distorted and ride centrally on the actu- ating cam to open their corresponding limit switch.
•Inspect the azimuth and elevation jackscrew boots for security of attachment at both
ends, for abrasion, tears, cuts, brittleness and other damage that may expose the jackscrew to the environment (water, dust, etc.). Minor repairs can be made with RTV- 108 silicone rubber sealant.
•Visually inspect the feed window for dirt and the feed, feed supports, feed window,
and reflector for distortion, foreign object damage and environmental deterioration due to ice and snow, dust, rain, hail, and high winds, etc. which may cause electrical compo- nent and/or structural deformation.
•Check the cable attachment to the resolvers and to the LNA or LNB’s and enclosure
mount interface for security, the cable rouging for secure hanger attachment and the cable insulation for cuts, cracking, abrasion, and other deterioration. Check the LNA or LNB’s and the resolvers for a secure mechanical attachment. Ensure proper torquing of polarization drive gear box setscrews and appropriate tensioning of corresponding drive chain assembly, if applicable.
•Check (if applicable) that the drain holes in the bottom of the enclosure are not
obstructed and there is no evidence of water accumulation. Check the enclosure doors for proper closure and that the door seals are intact, not torn, abraided or otherwise damaged. Check that all other seals are intact and if not, use a coating of
•Check for the appearance of surface lubricants that will cause the accumulation of dirt
and grime. Clean off all excess surface lubricants with a cloth and if required, a cloth dampened not wetted with trichlorethylene, or equal.
•Visually inspect all mechanical parts for freedom of operation with no misalignment,
binding or interference. Check all cabling for sufficient slack to prevent cable strain as well as adequate restraint to prevent abrasion or chaffing during antenna and feed movement.
•Check security of antenna mounting and interconnecting assembly hardware. Be cer-
62 | Preventive Maintenance |