Mike,
Your calculations are for the HORIZONTAL distance from the element tips
to the guys; however, the closest distance is PERPENDICULAR to the GUY,
and will NOT be one foot with your 'clearance'.
With guy & element 'sag' I estimate the guy will touch the element tips
UNLESS the element sag is the greater of these two 'sags'.
Better to emphasize to the antenna erector to lower the yagi to give
assured clearance .. [what's another two feet of antenna height?]
Don
N8DE
"Mike Gilmer, N2MG" wrote:
>
> 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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