Well, the tower is specifically designed to be guyed, and guy points are
welded to the tower at the top of each section. There is a shelf the
tower top section rests on, which is withdrawn by way of a thin rope
before the tower can be retracted.
I sent an e-mail to the manufacturer yesterday asking about this guy
tension business, and I'll convey the reply back here.
Dick Spindler, N9AM
----- Original Message -----
From: John Langdon <jlangdon@outer.net>
To: <towertalk@contesting.com>
Sent: Thursday, October 21, 1999 8:20 AM
Subject: RE: [TowerTalk] Crankup Aluminum Tower
>
> I doubt you would have much success devising some kind of "brush
assembly"
> to ground those top sections. I would ground the coax shield to the
tower
> at the top and bottom and use the Polyphasers as you suggest. I would
still
> ground the bottom section well, and have a good ground where the
cables
> enter the shack. Does the tower manufacturer say anything here?
>
> On the guying I would say that unless the tower is specifically
designed to
> be guyed, in which case follow the manufacturer recommendations, be
VERY
> careful. A crank up tower under guying tension is like a giant loaded
> crossbow, and if it fires some bad things are likely to happen. Do
not even
> consider this if there is no locking mechanism that takes the load off
of
> the crank up cable when the tower is fully extended. Even then, the
guy
> tensions projected into downward force can easily overload the locking
> mechanism or the tower sections themselves
>
> 73 John N5CQ
> .
>
> -----Original Message-----
> From: owner-towertalk@contesting.com
> [mailto:owner-towertalk@contesting.com]On Behalf Of Richard Spindler
> Sent: Thursday, October 21, 1999 6:54 AM
> To: towertalk@contesting.com
> Subject: [TowerTalk] Crankup Aluminum Tower
>
>
> I am in the process of erecting a nice AlumaTower crank-up 75 footer.
>
> This reflector has been a help in several respects, but some of the
most
> important issues discussed reveal that I am tower-savvy-impaired
despite
> reading what I can get my hands on.
>
> First, the issue of lightning protection. It looks to me as if the
> three sections of the tower are essentially insulated from each other
> with plastic pads which prevent them from rubbing against each other
> when the tower is cranked up. So it seems to me as if, even though I
> ground the legs to kingdom come with radials and multiple rods, the
> major lightning path is going to be right down the old coax. I'll
have
> PolyPhasers at the tower base and again at the entrance to the house,
> but that whole ground-at-the-tower-base issue seems moot. Am I
missing
> something here? Is there a custom of bonding the sections
electrically
> somehow? Looks like a real problem to me.
>
> Secondly, the issue of guy tension. I have read several treatises on
> properly installing and tensioning guys. It seems to me that if I try
> to tension my (PhillyStrand) guys to 10% of breaking strength, I am
> going to have a tough time cranking the tower up all the way in the
> first place, and have a pretty good chance of breaking the cable which
> cranks the tower up in the second place. I plan to guy each section,
> since we have a 100mph wind speed figure here in this county
(Highlands,
> Florida), so I would have nine guys tensioned. I don't see any
> information on this issue in the stuff I got from the manufacturer,
but
> I have written for it.
>
> There must be fellows (I hesitate to say "guys") here who have faced
> these issues. Any advice?
>
> Doc Spindler, N9AM
> Sebring, FL
>
>
> --
> FAQ on WWW: http://www.contesting.com/towertalkfaq.html
> Submissions: towertalk@contesting.com
> Administrative requests: towertalk-REQUEST@contesting.com
> Problems: owner-towertalk@contesting.com
> Search: http://www.contesting.com/km9p/search.htm
>
>
> --
> FAQ on WWW: http://www.contesting.com/towertalkfaq.html
> Submissions: towertalk@contesting.com
> Administrative requests: towertalk-REQUEST@contesting.com
> Problems: owner-towertalk@contesting.com
> Search: http://www.contesting.com/km9p/search.htm
>
>
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|