Here is what Rohn said in a 1980 catalog:
25G can survive with 33 ft maximum height above a well placed bracket with
a 2 sq ft antenna and 70 mph wind. This configuration is intended to be
used with tv antennas, not with the larger antennas used by us.
Going through the published numbers, by the time the wind reaches 90 mph,
the tower is about 10% beyond survival ratings with no antenna load at all.
Guy wires are our friends!
73,
Gerald K5GW
In a message dated 12/14/2015 10:28:09 A.M. Central Standard Time,
herbert.schoenbohm@gmail.com writes:
I thought that you could safely put 30 feet of Rohn 25 un guy above a
good house or side building bracket. That is what I use here for an
10/12/ and six meter tower but to get to 60' I have a set of Phillystran
guys at the rotor plate. The house bracket is in to 2X6 and they are
back by a long 1 X4 .of treated lumber with over sized washers and nuts.
Herb Schoenbohm, KV4FZ
On 12/14/2015 10:29 AM, Chuck Dietz wrote:
> And I would not hesitate to put up 30 feet of Rohn 25 with only one set
of
> guys at the top.
>
> Chuck W5PR
>
> On Mon, Dec 14, 2015 at 8:27 AM, Chuck Dietz <w5prchuck@gmail.com> wrote:
>
>> A couple of inverted V antennas could help the guying of a small roof
top
>> tower too...
>>
>> Chuck W5PR
>>
>> On Mon, Dec 14, 2015 at 7:19 AM, Ed Sawyer <sawyered@earthlink.net>
wrote:
>>
>>>
>>> Stan, K5GO said "At risk of purists saying absolutely not, if I were
going
>>> to put up just 30 feet of 25G tower and didn't have all the proper
>>> materials
>>> to insulate the guy wires and guy it as would normally be done, I
wouldn't
>>> hesitate for a moment to put two levels on that small tower using 3/8"
>>> diameter polyester (Dacron) low stretch rope. The antenna will blow
apart
>>> first eliminating a potential problem and rope doesn't rust."
>>>
>>>
>>>
>>> I would second Stan's suggestion for 2 reasons: 1) a spider beam is
going
>>> to
>>> collapse anyway under a really strong Hurricane wind and 2) whenever
>>> someone
>>> says "rooftop" tower, what they really are saying is "how strong are
my
>>> anchor points anyway?". This is all about the ability of the guy
anchors
>>> to
>>> support the pull of the tower in wind. Rarely is any roof connection
>>> system
>>> up to the task. By support with a strong rope, you kill many birds
with
>>> one
>>> stone and you likely don't add any weakness vs the anchor points.
>>>
>>>
>>>
>>> I had a 60 ft tower of 25G support by 2 sets of rope guys for 5 years
as
>>> my
>>> 160M vertical. It was heavy rope and there was a plate under the
tower.
>>> It
>>> was purposely not permanent because it was on a farmers land. I had
to
>>> remove it when the land sold. Now I have 2 T top wire verticals -
phased.
>>>
>>>
>>>
>>> Ed N1UR
>>>
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>>
>>>
>>>
>>> _______________________________________________
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>>> TowerTalk@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>
>>
> _______________________________________________
>
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