[Towertalk] Calculating guy distance for rotating towers

[kk9a@arrl.net]

I guess your guy wires run straight up and down.  If the guy was on a 45
degree angle adding 1' to the turning radius would only give 8 1/2" of
clearance.

----- Original Message -----
From: "Mike Gilmer, N2MG" <n2mg@eham.net>
To: <towertalk@contesting.com>
Sent: Friday, October 11, 2002 7:18 AM
Subject: [Towertalk] Calculating guy distance for rotating towers


Oops, somehow the word "Boom" got into this thread... "Boom" is the
wrong term - changing the boom length is not the same as changing the
turning radius (in most cases!)

In my original post (bottom) I said it correctly: adding one foot to
the "turning radius" - not adding one foot to the "boom" - and
recalculating gives one foot of clearance.  We *were* talking about
"turning radius" all along anyway, but I just want to be clear.

-Mike


N2MG wrote:
> I disagree.  If you push the guy out from the tower by one foot
> at the spot where the boom would otherwise hit it,
> you've added one foot to the clearance.

> To push it 1 foot away at the example's 60-foot height, the
> anchor moves 5 feet away.

> KK9A wrote:
> > Adding 1' to the boom does not give 1' of guy clearance unless
> > the guy runs straight up and down.  Guy clearance should be
> > measured perpendicular to the guy. In this case for 1' of
> > clearance the guy would be at a 29 degree angle and the anchor
> > would be 136' from the base of the tower.

> > N2MG wrote:
> <SNIP>
> > > This makes guy anchor distance x = 125' for zero clearance.
> > > To get 1 foot of clearance we change the 25' turning radius
> > > to 26' and get: 130'  Then there's ground irregularities and
> > > guy wire sag so you may opt for more minimum clearance.
> > > Lower the antenna 5 feet and the 1-foot clearance anchor
> > > spacing is only 98 feet  Big difference.  Of course, if you
> > > have the room and the EHS...

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