His question is how do you determine the tension requirement for mixed guy
materials. I would recommend using the lowest tension that you would get if
each material were used for the whole guy... that will probably be the 400# for
3/16"ehs if i am reading all those materials correctly. you don't want to
overstress anything by using a higher preload than necessary, and since 3/16"
ehs is the standard material for guying rohn 25 that should give close to the
proper side forces even if it sags a bit more because the other stuff is
heavier.
May 9, 2011 03:38:59 PM, K7LXC@aol.com wrote:
In a message dated 5/9/2011 12:01:06 P.M. Pacific Daylight Time,
towertalk-request@contesting.com writes:
> I have a 97' Rohn 25 tower mounted on a pier pin. The guys are at 92,
61, and 31 feet above ground. The tower has 2 C-3E tribanders at 69 and
98 feet, and an EF-240 on a 10-foot mast above the top yagi. We're in a
pretty benign wind environment.
> Now here's the complex part. I want to re-tension the guys, which were
originally set a number of years ago at 400 lb all around, and I figured
as long as I am doing this job, I should do it better, if possible.
Why? Because each guy set is made of different material, and I suspect
that should/might influence the desired pre-set tension.
> The top guys are 6700-lb Phillystran down to about 15 feet above
ground,
and 3/16 EHS below that. I know it's a mismatch, but I got the Philly
guy sets cheap.
> The second set of guys use Joslyn 21-foot fiberglass power-pole
insulators on the tower end, and 3/16 EHS the rest of the way to the
ground. These insulators are only a little heavier than EHS of the same
length, but pretty stiff, as you might expect.
> The third set are 3/16 EHS all the way, insulated at the tower.
> My question is this - what, if any, adjustment would you make to the
400-lb pre-tensioning value for each guy set?
I'm not sure what your question is but this is a typical
plumb-and-tension job. Start at the bottom and make sure the segment below the
bottom guys is plumb. When it is, tension the guys to the prescribed tension.
Repeat as necessary as you go up the tower to the next set of guys.
Cheers,
Steve K7LXC
TOWER TECH -
Professional tower services for hams
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