Rotor repair hints and links received from the AMSAT-BB group
Here are some pictures from the repair of the G-5500 Az/El rotor which had been installed for 2.5 years. Symptoms were sluggish, or no, elevation movement. Upon disassembly found the local salt spray and rain had intruded into the rotor assembly. Bearings were rusted and the retention assembly broken.
(Click on images for larger size.)
Antenna and rotor up and running for AO-40 on homebrew mast. Note large body of salty water in background!
Here's what the elevation rotor looked like prior to opening. This photo was invaluable during reassembly to get the shaft in proper alignment.
At least the gears are OK, but need grease.
You can see the moisture on the top of the capacitor, droplets on the connector housing, and some drops on the inside of the aluminum case.
(28 Feb 2005) Rotor disassembled. Note salt deposits. Missing bearings in left section. Rust from bearings. There were large water droplets visible inside when the unit was disassembled. (Required an impact driver to free all eight of the #3 Phillips head screws.)
(2 Mar 2005) Housing cleaned, masked, and ready for priming.
(3 Mar 2005) After thorough cleaning, including rinsing in vinegar just prior to priming, the housing is primed inside and out, along with capacitor mount which had some minor surface corrosion. No zinc chromate could be found locally, so aluminum primer from the hardware store was used. Screw holes were masked, as well as the facing where the two housing sides meet.
(3 Mar 2005) Both housing halves are painted and ready for the new bearings. Also, the capacitor mount has been primed, painted, and reinstalled.
(4 Mar 2005) The bearings and retainer clips arrived! Surprise - There are 40 bearings in each bag, so I've ordered too many. Will keep them for "next time". The retainer clips ("bearing ring") come two to a bag.
(5 Mar 2005) The bearings and retainer clips are mounted and ready for grease.
(5 Mar 2005) The bearings and retainer clips are greased and ready for the final assembly and test. Used Sta Lube Moly-Graph multipurpose automotive grease. Will open the housing in a year or so and see how it held up.
(5 Mar 2005) Everything is reassembled and bench tested to ensure the limit switches were working. Both housing halves were lightly coated with RTV liquid gasket before final mating. Replaced the original Phillips head screws holding the two halves together with hex head screws. Early pictures of the unit before it was disassembled were invaluable in getting everything aligned correctly.
(5 Mar 2005) Sure don't want to mount my nice elevation rotor on this rusty bracket. So, removed, cleaned, primed, and painted it, too.