76
•
Check all electrical components for dirt, cracks, chips, breaks, discoloration and other
signs of deterioration and damage. A discolored, blistered or burnt condition is evidence
of overload.
•
Operate the azimuth and elevation drives as well as the feed rotation in both the plus
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 limits 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 component
and/or structural deformation.
•
Check the cable attachment to the resolvers and to the LNA or LNBs 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
LNBs 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, abraded or otherwise
damaged. Check that all other seals are intact and if not, use a coating of RTV-108 (sili-
cone rubber sealant) to seal any exposed electrical fitting, bolt hole, or other possible
water entry to electrical components in order to maintain a weatherproof condition. If the
enclosure is provided with a vent fan, check for free operation of the fan blade. The fan
bearings are permanently lubricated; any binding, abnormal noise or vibration necessi-
tates replacement of the fan assembly. Check and replace the fan filter element if it
appears dirty or obstructed with dust.
•
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.
Preventive Maintenance
