Dave --
You own a dangerous tower.
Sorry to point this out, Dave, but your tower is not very strong.
Go to http://www.ustower.com/selfsupport.html
and look at the weights and section sizes for a US Tower.
The weight of a 72' light-duty tower is 1040 lbs. The base
face width is 21 5/8" . Tower strength increases greatly with
face width (probably cube or 4th power - a PE would know).
Note that the US Tower ratings are for 50 mph. The
minimum you should design for is 70 mph. Higher wind
speeds are mandated in some counties.
Regarding guying a crank-up tower, it is not usually a good
idea. Guys create very large downward forces. If you were to
add 4 sets of guys to that tower, you would be expecting the
crank-up cable to counteract the downward force of 12 guys --
you better have a big cable! Note: the closer guys are to the
tower, the greater the downward force for a given horizontal
force.
This is very blunt, Dave, but I would not erect an 80' crank up tower
that was light enough for two guys to lift -- particularly
if the face width was only 14". This is a serious safety matter.
The tower is dangerous. There are many other problems with
your analysis of this project. You are not nearly ready to do this.
Keep reading this reflector until you are. Towers can kill.
Please understand that it would have been much easier for me
to ignore your post, than to respond. If you do not believe me,
please ask a PE. It is not my safety at risk - it's yours.
Tom Wagner - N1MM
----- Original Message -----
From: Dave H. <wiseguy@attitude.com>
To: <towertalk@contesting.com>
Sent: Friday, October 08, 1999 2:46 PM
Subject: [TowerTalk] newbie, Installing a 80' crank up .
>
>Hi to All,
>
>
>I am a new member to this fine forum of information "Tower Talk".
>
>I have just purchased a 80' crank up Tower . Dont know the manufacture .
>This tower is extremely heavy (two guys can barely lift it off the ground)
>it's galvanized and is in 20' telescopic lengths.it is made of 1" tubing,
>the largest section is 14" x 14" x 14" (a triangular design) (inside ones
>are smaller than the next 4 total= 80') The tower has "ears" at the top of
>each section or tabs to connect guy wires to them. The tower is a ladder
>design and cross bars are horizontal (ladder type) not Chris-cross . A bar
>design,(as opposed to a (X) design.) I hear this is not strong like the X
>design.
> It can be laid over on two bolts/pins, tilt up into place and then one
>would add the third pin to the base plate.
>these bolts don't seem strong enough to do much of anything other than to
>keep it into place on the 3/4' steel base plate which has 4 large holes at
>the corners for the base bolts (1" I think) the use of 2' long "J" bolts
>might work well here.
>I was thinking of a 3x3x3 base pour 4" above grade, since the tower is not
>of the "free standing" variety.
>But, I live where the soil is considerably heavy,(California Desert) when
>the soil is saturated it becomes terrible, and in the summer months it is
so
>hard I have to drive a spike with a large hammer in the ground just to put
a
>sprinkler in place (the type with a 7' spike on 'em)
>
>As far as placement on the property goes, I have enough property to locate
>it anywhere. So, the $64K question is...do you guys think it should be
AWAY
>from the house? or, NEXT to the house? if we go next to the house, one set
>of the the guys will be in the front yard. Since I have more than ample
room
>on this property for the tower and guying. If I set the tower away from the
>house how far should this be? and do I run the cables down a nearby guy
wire
>or underground from base.?
>
>I am guying it 3 ways (120 degrees apart).
>One of my main concerns is the degree of guying the antenna down. I want to
>get away with going with 30 degrees. Should it be guyed at each 20' section
>or one near the top and one set at the second section? which is @ 40'. I
am
>going to be running 10 meters, I have a 8 element beam by Avanti (AV-140)
>some know it as a "Moonraker IV". (dimensions are 19' boom, from top to
>bottom each element is 20' has horiz. and vert. elements) this antenna has
a
>wind load of only 5 sq.. ft. and weighs 24 pounds so with this factor, I
>want this thing to last through "super cell storms" with no problem.
>eventhough I live in a mild climate.
>I would like to guy with "poles" so one can walk around the pole rather
than
>trip over ground level turnbuckles. Any comments?
>The prevailing winds are from the NW and there can be gusts of what I've
>seen in the past 11 years here of about 40 mph. So, would pointing or
guying
>a tower directly into the prevailing winds benefit the load better or
should
>I consider the placement of the guy wires first and formost in the
>landscape? what about running two guys off same eyelet at 60 degrees into
>the prevailing wind? or does this matter at all.?
>Also the issue of running a solid run of guy wires, is it truly necessary
to
>break these up with insulators? I heard 22' to be the rule. I would think
>just run the guys solid all the way to the tower.
> I think the solid run of a guy is important and that I shouldn't worry
>about breaking them up for ''coupling or resonance" issues. I just was
>worried about the vertical elements getting too close to the top guys and
>that they are metal because, The worst part is at the top. this antenna has
>9' vertical elements from the boom. if I guy at the top eyelet, the tower
>won't rotate. Is this solved by guying at 10' lower point on tower, or
using
>a 10' section of mast putting antenna well above top plate? or how is it
>going to turn a vertical beam?
>
>I'll need to look into the anchors as well. What do you think about having
>them at ground level with big turnbuckles on them. OR getting a large
>diameter. pole as to be able to walk around the guys since they terminate
>5-6' on to of the pole?Whatever type I decide on they will be cemented in.
>so I need to know what dimensions of a base pour these "anchors" should be.
>and about these "anchors" are the holes wide? or just deep?
>Guy wire cable size is of importance I think. should I look at 1/4 " ? or
is
>that an over kill?
>
>. I need info on base pour dimensions, grounding, guy wire distance from
>tower, type of anchors/posts for guys, insulators on guys set for 10-11
>meters,(resonance/reflector issues) ANY and all suggestions will be
>appreciated, as I am just starting out. If you know of web sites or reading
>material for this, please help,
>
>As I will need to climb the tower (at lowest setting) to add the antenna,
or
>will have to hire a truck.
>
>Thank you all for any feedback concerning this achievement, For the
>"hoisting" of this construction , I will offer folks around here " an
>erection party". hehe
>
>73s
>Dave H.
>
>
>--
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>
--
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