[TowerTalk] Rotor on AB577

Tue May 31 20:00:05 EDT 2005

The same thing happened to me -- twice as well. The aluminum casting broke. 

The first time it was a clip on one of the launcher guy wires. That wasn't a
terrible problem because the top and middle guys apply sufficient downward
force to keep the launcher from slipping out from under the mast. I quickly
replaced the broken clip with a steel screw link available at any hardware
store. 

The second time it happened, a clip on one of the top guys on one of my
50-footers snapped. My AB-577s are hidden behind trees, so I didn't know it
happened. By great good fortune, I did a little tower inspection before CQ
WW and found the break. No telling when it happened, but it could have been
a month or more earlier. This was a serious problem -- one stiff gust of
wind and the whole tower would have come down! I guess the 5-el 15m
monobander was a small enough windload that it hadn't happened yet. I raced
to the garage to get the winch and tube wrench, donned my hardhat, ran back
to the tower and lowered it in about five minutes flat. Whew! This time I
had a supply of steel screw links on hand to effect the repair. Had the
tower back up 45 minutes after discovering the broken clip. This was with
about a foot of snow on the ground.

Some AB-577s come with forged steel hoist hooks and some come with cheap
cast aluminum clips. One of my AB-577s, which was purchased from Ontario
Surplus in mint "unused" condition, had steel hoist hooks and all-stainless
guys. The other two AB-577s were used-refurbished units that had cast
aluminum clips and plastic-coated galvanized steel guy wires. While it might
seem that cheaper parts were substituted when the towers were refurbished,
that may not be the case. The manual clearly shows the cheap cast aluminum
clips in several pictures and drawings. I suspect the Army had the same
problem we did, and possibly had problems with the plastic-coated guy wires,
and had the manufacturer respecify the AB-577 to use forged steel hoist
hooks and stainless guys. In any case, the clips and hoist hooks are
attached using a nicopress machine and the length of the guy is usually
stamped in the sleeve. The joints appear to be either factory-made or
professionally refurbished.

I'm planning on replacing all the cast aluminum clips and plastic-coated guy
wires on my two AB-577s that have them. The clips need to be replaced for
safety, but the stainless wire rope is a bit of a luxury. But I've found
that it works much better in the snubbers than the plactic-coated wire rope.
Last year I proved out the technique by making custom guy sets to extend my
third AB-577 (the mint one) to 75 feet. I had to do this because extension
kits haven't been available for years. The extra tubes and middle guy rings
(very expensive now!) are still available, but the longer guy sets are gone.
So, I bought a bunch of the regular guy sets, removed the shorter guy wires,
and fabricated new guy wires using the empty snubbers. I bought enough
regular guy sets to make extensions for all three towers, and I'm afraid I
cleaned out the last of the spare guy sets Ontario Surplus had! 

The project required 1/8" stainless wire rope, 1/8" zinc-plated copper
duplex sleeves and a hand swaging tool. All this came from an outfit called
Web Rigging Supply (www.webriggingsupply.com) They cut the stainless wire
rope to the lengths I needed for six guy sets at no extra charge. I also
ordered forged steel hoist hooks. They're the right size, but they're a bit
too wide to fit the guy ring slots. That's been the case with some of the
hooks that came with the mint tower, too, and in that case I had to file
them down. Instead of doing that, I used the hoist hooks from the discarded
guy wires I removed from the snubbers I bought. All of these happened to be
the right width, and look like something the Army may have ordered up custom
-- I haven't been able to find these narrow hoist hooks anywhere. When I
replace the guys on the other two towers I'll probably just file down the
fat hooks and repaint them.

I had to develop a technique and practice a bit, but the hand swaging tool
did an excellent job -- every bit as good a joint as those made by machine,
and a lot more sturdy than wire rope clips. Wire rope clips have no load
ratings, so it's really a guessing game what forces they will withstand. The
swaged joints are rated well beyond any forces that would be applied to the
guys. Web RIgging Supply now had a bench-mounted swaging tool, had they had
it when I ordered the parts last fall I probably would have spent the $40 or
so extra for it.

This is all probably more than you wanted to know, but I find it an
interesting subject and hope other AB-577 owners do too!

73, Dick WC1M

> -----Original Message-----
> From: ChetMoore [mailto:ChetMoore at cox.net] 
> Sent: Monday, May 30, 2005 11:18 PM
> To: Jerry K3BZ; Dana Roode; towertalk at contesting.com
> Subject: Re: [TowerTalk] Rotor on AB577
> 
> 
> I did exactly what Jerry suggested.    One more thing,  Two 
> of the Clips on 
> the guy wires that came pre attached to the color coded guy 
> wires on my unit 
> broke on two different occasions.  I would recommend 
> replacing those all of 
> these clips with  stainless steel or brass clips or  cutting 
> the original 
> clips off , and use  a thimble and wire clamps
> 
> Chet N6ZO
> ----- Original Message ----- 
> From: "Jerry K3BZ" <k3bz at arrl.net>
> To: "Dana Roode" <dana.roode at gmail.com>; <towertalk at contesting.com>
> Sent: Monday, May 30, 2005 8:48 PM
> Subject: Re: [TowerTalk] Rotor on AB577
> 
> 
> > The top cap on my AB577 tapers down to 2.75" OD, and with 1/2" wall 
> > thickness the ID is 1.75".  A short piece of pipe will fit in the 
> > 1.75" center hole.  Drill a hole thru the pipe to accept a 
> 3.5" bolt 
> > so it extends out , such that when you insert the pipe in 
> the hole the 
> > bolt fits neatly into the slot in the top cap. That holds the pipe 
> > "mast" and keeps it from turning so you can mount your 
> rotator on the 
> > pipe. Of course the bottom clamp on some rotors (such as 
> the AlfaSpid) 
> > will expand to fit 2.75" so you
> > can mount it directly onto the top cap, with the antenna 
> mounted to a 
> > short
> > piece of pipe on the top.
> >
> > Just some ideas.... 73,  Jerry K3BZ
> >
> > ----- Original Message -----
> > From: "Dana Roode" <dana.roode at gmail.com>
> > To: <towertalk at contesting.com>
> > Sent: Monday, May 30, 2005 8:34 PM
> > Subject: [TowerTalk] Rotor on AB577
> >
> >
> >> Hi all,
> >>
> >> I have a AB577 mast and I need to put a rotor on it - if 
> someone out 
> >> there has done this and would like to share your approach with me, 
> >> please drop me a line.  I built an adaptor I am not completely 
> >> satisfied with out of the top piece I got for the 577.  
> Does anyone 
> >> know if other top pieces for the mast are available 
> somewhere?  For 
> >> example, a mast adaptor to take the 5" diameter mast down to 2"?
> >>
> >>   Dana
> >>   k6nr at arrl.net _______________________________________________
> >>
> >> See: http://www.mscomputer.com  for "Self Supporting Towers", 
> >> "Wireless
> > Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 
> > with
> > any
> > questions and ask for Sherman, W2FLA.
> >>
> >> _______________________________________________
> >> TowerTalk mailing list
> >> TowerTalk at contesting.com 
> >> http://lists.contesting.com/mailman/listinfo/towertalk
> >>
> >
> >
> > _______________________________________________
> >
> > See: http://www.mscomputer.com  for "Self Supporting Towers", 
> > "Wireless
> > Weather Stations", and lot's more.  Call Toll Free, 
> 1-800-333-9041 with 
> > any questions and ask for Sherman, W2FLA.
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk at contesting.com 
> > http://lists.contesting.com/mailman/listinfo/towertalk
> > 
> 
> 
> 
> 