Re: [amsat-bb] To open, or not open it

[Bruce Nolte N3LSY <brucenol@xxxxxxx>]

Francisco Costa wrote:

>----- Original Message -----
>From: Paul Willmott <pwillmott@northrock.bm>
>To: <gjmouse@neo.rr.com>; <amsat-bb@amsat.org>
>Sent: Wednesday, October 09, 2002 11:19 PM
>Subject: Re: [amsat-bb] Yaesu Rotor REPLY
>
>  
>
>>I havn't cracked the case open yet on the 5500 unit, I need to get an
>>    
>>
>impact
>  
>
>>driver, those screws are in tight!
>>    
>>
>
>They sure are!
>I have my 5400 down, and before I put it up again
>(on the new tower) I thought it might be a good idea
>to do maitenance on it, in order to avoid future problems.
>The first job was to gave an anti corrosion treatment to
>the U bracket (that connects the az with the ev rotator)
>who was looking pretty rusty.
>The second task was open the elevation rotator and
>replace grease and any bearing ball (if necessary).
>Well, even with an impact tool, opening the case wasn't
>easy as I supposed it was. I only removed one screw,
>and the head was so damaged I can't use it anymore.
>So, I question myself: should I gave up my inicial idea
>and trust luck, or open it and do the job, even I have
>to smash all the screws?
>Any opinion from "rotator guru's" is wellcome!
>
>73 F.Costa, CT1EAT
>http://www.qsl.net/ct1eat
>
>P.S. FYI, the unit is working fine (since 1996) and has been
>        light used. Not much strong winds, but many days of
>        hot temperatures...
>
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>
>  
>
I have torn down my 5400 twice, including once during Field Day a few 
years ago to clean up some unnoticed ball bearing corrosion after buying 
the rotor used, and again to repair it properly before mounting it 
outside. The innards are not terribly complicated, just lots of loose 
ball bearings and a few gears in addition to the motor, but rebuilding a 
rotor can be a messy proposition. Open it up on a table covered with a 
Terrycloth towel to catch the bearings as they roll out, or you will be 
chasing them for weeks.The balls in the Elevation part do have a race 
IIRC, but once it is out of the rotor, the balls tend to go everywhere.

 Once the bearings are removed,  put them in an old coffee can partially 
filled with Kerosene or paint thinner and swish it around for a while 
until all of the grease is removed. Once the balls are clean, inspect 
them for pitting, and replace any that are pitted.   Clean and inspect 
the bearing races, (hopefully they are in good shape), minor burrs and 
rough edges can be sanded out, but if the pitting is deep, then order 
new races, along with any bearing balls that need to be replaced. Norms 
Rotor Service has a good deal on the balls, about $15.00/100 for the 3/8 
inch balls you will need for the azimuth rotor. I forget what size the 
elevation rotor balls are,  so measure them before ordering them. Clean 
and check the geartrain, and if you will have trouble  remembering how 
to reassemble it, make a diagram of what goes where. Make sure the 
wiring is in good shape, and make any necessary repairs. There is a 
drainhole in the middle of the Azimuth rotor lower housing that must be 
clear. Make sure it isn't clogged with corrosion or debris, and you 
might want to enlarge it a little.

When reassembling the rotors, I like to use white lithium based  grease 
to pack the races. It is water resistant, and is not so heavy that your 
rotor becomes sluggish on cold days. Don't overpack the races, or the 
grease will start oozing out all over the place. Also, make sure the 
limit switches line up with their actuator inside the housing before 
bolting everything together, and do a quick operational check while it 
is still on the bench. A spare piece of scrap thermostat or  CAT 5 cable 
will suffice as a control cable for short distances with an unloaded 
rotor. It is a lot easier to test a rotor on the bench than to deal with 
an assembly or other unforseen problem once it is on the mast or tower 
and antennas are mounted on it.

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