In a message dated 98-08-30 19:17:36 EDT, lburke@wt.net writes:
> Finally got finished with my tower project today: 80 ft of 45G with a 20 ft
> 3/8" wall CrMo mast and 10M, 15M, 20M KLM monobanders on top. I guyed the
> tower per the Rohn catalog. This puts the top guy down several feet from
the
> top of the tower. Found out after the fact that this configuration is
> intended for commercial installations more than heavily loaded ham
> installations. When you get to the top with the load I have, it's pretty
> obvious why. A good twist on those long booms can torque the tower. But it
> sure made it nice putting up the beams.
>
> My question is this... rather than move the guys and brackets up to the top
> of the section (where it would make it difficult to haul up and take down
> yagis because it's in the way) should I add a "third" guy of Phillystran on
> the ears of the top flat section?
Congrats! Lots of work but it sure looks nice up there.
Having the guys a couple of feet below the top is okay. The Rohn spec
includes a big 'headload' even with the guy points a couple of feet down so
you're not violating anything.
If your rotator is below the top set of guys, then the big torque is
being transmitted down below the guys anyway so the additional exposed tower
is just additional 'big' mast.
Since Galveston County is a 100 MPH windspeed zone, you may want to go to
the trouble of moving moving the guy points up. You can do it in a couple of
hours by using a temporary guy and a couple of cable grips and comealongs.
>The other guys are EHS, and I've heard
> arguments against adding extra EHS guys. Is that strictly because of the
> weight of the EHS or the downward force any additional guy tension may have
> on the tower? With this "extra" set of guys, I could drop them when
> adding/removing antennas while keeping the two sets of EHS in place. I
> really don't think it would be a good idea to move the current top set of
> guys without some sort of temporary guying... particularly with all that
> stuff up there. And if I'm going to install temporary guying I may as well
> put up the permanent stuff. Will cost another $400 or so, but that's small
> change compared to what I'm trying to protect.
How big are the antennas - weight, boomlength, size? Did you build it to
100 or 110 MPH spec? I think that while the additional set of guys is
redundant, it might be worth the psychological insurance. I'd move the guys up
instead of adding another set.
Cheers, Steve K7LXC
www.championradio.com
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