[ARC5] Power up Modulators

[David Stinson]

-----Original Message-----
From: "Todd, KA1KAQ" <ka1kaq at gmail.com>

To add just a bit to the excellent post by Dave, I would throw in the
tidbit from Mike Hanz about cleaning and repacking all dynamotor
bearings that are accessible (not sealed), if you intend to use them.
Apparently some folks don't use them on receivers due to noise and
interference issues. Hopefully Mike or others with dynamotor
experience will chime in. Do you use them, Dave?
---------------

I do indeed.  And I'm probably going to
make Mike mad at me here ;-).
Mike is wise to pull, clean and repack the bearings
on his dynos and that's certainly the best idea.

I don't have a bearing puller. 
I don't think many of us do. 
Bearing pullers scare me.  I don't see how you 
can pull them off like that without tearing them up.
You'd think the race would pop off the balls or something.
Raises the hair on my neck when I see someone do it.

Now, if my dynos were going to be running for hours and hours,
I'd go buy a bearing puller and get over it.  
But they don't; they run for one to four hours, 
maybe twice a month, if that often.  
Hold onto your jaw, Mike,  cuz here's what I do:

I pull the covers off the ends of the dynos
and open the bearing covers, being careful
to note any shims or such things so they go back
in the same way they came out.
If the grease in there looks "wet" and servicable,
I drop in several drops of high-quality electric 
motor bearing oil.  I spin the armature with my thumb
to get the oil down in the bearing so it will mix with
the grease, then put in more
until it won't take any more, being careful not to add
so much that it goes running out the back or makes a mess.
Then I put the shims back in, the bearing covers
back on and throw the juice to it.  I listen for 
rattling bearings and watch for over-sparking 
brushes that say "I'm dragging here."
 95% of the time the dyno runs up fine
and the bearings run cool and happy over the 
hour I let it run.  I constantly check them to see if
they're flinging out junk or getting hot.
After an hour's run, I reopen the bearings and 
see if they look lubed, wet and happy.
If they do, it goes into service and "God protect the foolish."

If the grease looks oxidized and "dried out" 
crumbly, I go ahead and remove the armature 
and "pick out" as much of the old grease as I can
with a wooden tooth pick- no metal that might
scratch the balls or race.  A little petrolium product
like kerosene and a tooth brush will get the itty bits out.
Then I use my thumb to mash as much 
Mobil 1 High-speed, synthetic bearing grease in 
there I as I can get it to take, turning it several times
and cleaning any "push-through" out of the grease
slinger with the toothpick.  Then I put it back together,
say a "Hail Mary" and let'er rip.
I check it after an hour to see if it's "doing OK."

After dozens of dynos, I've never yet lost a bearing
that wasn't damaged or worn when I got it.
Now, if I was going to run these things constantly for days,
I think it would be wise to go "whole hog" and do it
according to the wisdom of our resident master
machinist.  As I said: I've run them for hours 
under "hobbiest duty cycle" conditions and they
don't get hot or go bad.  At least, no yet.

OK, Mike-  I *know* you're right.  
I *know* I should buy a bearing puller
or just take the armatures 
to a motor shop and let them do it.
I'm just an old sinner.... ;-).

73 Dave S.