Sorry if this ends up being a re-post. I sent it 20 hours ago and still
haven't seen it pop up on TT. Maybe that was caused by CCing the message to
a couple of addresses at U.S. Tower. I thought it was a no-no to put the TT
address in the CC field, but does the reflector also reject any message with
anything in the CC field?
Anyway, that's not the important question here. Please read on.
> I am in process of putting up a ma-770 tower. I also asked USTower about
> lubricating the cables and they said don't. They had several reasons for
> this advice. The ones I remember are: (1) most lubricants tended to
> collect debris, twigs, dirt, etc which interfere with the cable path, (2)
> they had heard anecdotal reports from users that penetrating lubricants,
> that would not collect debris, seemed to hasten rusting, but they did not
> have evidence on this themselves either way, and (3) in their experience
> they had never had any trouble not lubricating the cables over several
> years of use. I don't remember them mentioning what the cable manufacture
> recommended.
As an owner of a two-year old U.S. Tower MA770MDP, I've found this very
important subject to be incredibly frustrating. When I first bought the
tower, Bruce Kopitar, the owner of U.S. Tower, told me not to lubricate the
cables. He did say that it would be OK to lubricate the pulleys, but not the
cables.
Of course, U.S. Tower also recommends that the cables be replaced every
three years. I seriously doubt that any lubrication would be required if the
cables were replaced on such a schedule. However, given the expense and
difficulty of doing so (the antenna has to be removed and the sections have
to be disassembled), I'm sure that few, if any, amateur owners of their
towers actually replace the cables every three years. I figure 6-10 years is
a more realistic figure. That's why the subject of lubrication is so
important to us.
I should point out that lubrication of the cables on a tubular tower like
the MA770 is somewhat problematic: the two upper cables are inaccessible
inside the section tubes when the tower is retracted, and cannot be reached
when the tower is extended. It is simply not possible to lubricate them. It
is possible to lubricate most of the main cable, but a short portion of it
remains inside the lowest tube and cannot be accessed at all. There are also
portions of the main cable that can only be accessed with the tower tilted
over.
As many of you know, the advice from virtually all the experts on Tower Talk
is to lubricate the cables with a special lubricant designed specifically
for wire rope. I bought a can of PreLube 6 from our own K7LXC, but never
used it. That's because another expert, Skip, KJ6Y, told me that the motor
drum on my tower, which uses a single-layer spiral path, holds the cable
(and the tower) in place by friction and that lubrication may cause the
cable to slip in the grooves and the tower could gradually slide down. So I
never used the can of PreLube 6.
Next, Joel, owner of First Call Communications, a major distributor for U.S.
Tower products, strongly recommended lubricating the cables. He sells a
special lubricant called Whitmore's designed for the purpose. When I pointed
out the discrepancy to Skip, he conferred with Joel and was told that the
lube sold by First Call would not cause such slippage. Skip then recommended
that I lube the cables with this product. I bought a couple of cans and have
been intending to lube the cable this Fall.
I read with concern the stories from Jim, KH7M, about the cable failure on
his MA550. His cable rusted and broke after seven years of operation near
the seacoast in Hawaii. Jim did not lubricate the cable. If I'm reading
Jim's report correctly, though, he has the manually winched version of the
MA550, where unused portions of the cable are wound on top of each other on
the winch drum. I can see where water could collect between the cable turns
on a drum like that and sit against the cable strands for long periods of
time without evaporating. In my setup, the cable runs in a single layer
through the spiral drum grooves. I think this would tend to promote faster
evaporation and less danger of rusting on the drum.
I've gone back and forth on this lubrication issue, and now I'm not sure
what to do. Follow the K7LXC prime directive and always do what the
manufaturer says? Should I do what the tower manufacturer says or what the
cable manufacturer says? I've copied U.S. Tower on this message and would
appreciate it if they would *please* comment on the subject of lubricating
crank-up tower cables. We really need to hear the advice from the source.
73, Dick Green WC1M
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