My 2c from some rebuild experiences
Hams seem to think grease lasts forever. Bearing manufacturers state 5
years, but I think that is conservative. Precision greases have a "use
by" date. Now put a rotator in direct sun and elements and who knows.
What I found in several rebuilds was dry races with divots from balls
sitting in one place too long (fretting corrosion), and rusty balls.
Rotators from SK estates may not have been rotated for years.
OTOH, cleaning up the sludge, installing new SS balls, taking a little
220 grit to the divots and my refurb 2800 SDX has been up for 8 years,
big 4L steppir, working fine. I use full synthetic grease - Superlube.
Same for a Ham-IV. Same process for a pre Yaesu G-5500 EL-AZ which had
leaking ends, trashed balls, rusty gears, now works ok, but a more
difficult refurb. There really are no "seals" as such (like RS ball
bearings) in what I have disassembled, just a configuration that sheds
water when upright. Not good if stored outside laying down.
The bad news is plain steel ball bearings in a die cast aluminum race is
a bad idea (except for cost), but the good news is the mechanism is so
sloppy it doesn't matter much. Keep the water out and lube it every
5-10 years and I think they will last a long time as "no maintenance"
Hammy Hambone regularly demonstrates.
My advice for a Yaesu disassembly is keep careful track of the top and
bottom section registration and the pot position and put it back
together exactly the same way.
Older ones are a big caveat emptor, but if they rotate and indicate, are
perhaps a good refurb candidate. About $50 for balls and grease and your
time and the risk that something else is wrong inside.
Attractive pricing at a hamfest - SDX $200; DXA $400 assuming
demonstration. I value the Yaesu controller at zero, they've been
offered for free on towertalk when replaced with a GH.
Grant KZ1W
On 3/2/2020 19:07, john@kk9a.com wrote:
Good advice Jim. I think that it's silly to exclude most of the US ham
population from buying it by not offering shipping. This is an aluminum
rotator that weighs 15 pounds. I brought three of them to Aruba.
John KK9A
jimlux wrote:
Certainly no more than half the new price.
Think of these in terms of:
1) what was the original warranty (I assume you're selling as-is)
2) What is the design life? What's the wear out component and how much
of its life is left?
This is kind of tricky - there are plenty of electric motors out there
that are 100 years old and still working - but that doesn't mean that
they were designed to last that long - you might have gotten lucky, or
the loads were low, etc.
In the case of used gear you don't really know the history - sure, the
ham selling it to you (if alive) will say that it was never abused, but
oh yeah, there was that wind storm 10 years ago which bent a bunch of
the elements on his antenna. Nobody has *real* usage data (like you
would with a regularly monitored mechanical system).
I would think that the wear out parts are things like bearings, seals,
feedback pots, etc. What affects its wearout? temperature, ice, water,
mechanical loads. These are all hard to estimate. It's not like a car
engine, where you've got X hours of running at Y RPM, against a rated
bearing life of Z hours.
I would assume, without other information, that the useful life of
something like this is 10-15 years - I can't imagine a company
*designing* for a 20 year life for a piece of consumer gear. Therefore,
the 15 year old one is basically at "scrap value" - what are the parts
inside worth if someone wanted to use it to fix something else, or if
they were going to sell it as scrap metal. If someone happened to need
the control box, or the connectors on the cables, it might be worth a
bit more *to that one person*.
The 2 year old one that's been outside, but not operated? A lot would
depend on the environment, and what the seals are like. It's probably
not "worn out", but if something sits, unmoving, through rain, ice, sun
beating on it, etc., it might have developed leaks, or the elastomers
have gotten stiff.
It's not under warranty. Maybe half the new price if *everything* is
like new and there's no obvious damage.
At some point, too, you've got to decide if shipping 40-50 lbs is worth
it. Shipping UPS for something that size is about $75-80 depending on
where it's going.
There are few if any recent examples on the usual swap forums and I’d
like to sell them locally (they’re very heavy).
- The first is a used G-2800 SDX rotor and controller. Nothing special
other
than its fully functional with all parts included. It had been mounted on
a
tower for 15 years rotating a VHF stack (6, 2, 1.25 and 0.7-meter yagis).
- The second is a relatively new (1 ½ years old) G-2800 DXA rotor,
controller and tower shock absolver. The controller has the optional
remote-control interface installed. It had been mounted on the tower but,
the owner passed away before the full VHF array could be assembled. It’s
also fully functional with all parts included.
Any advice would be appreciated.
(this is not an offer to sell them)
73, Jim
K0MHC
Kerrville, TX
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