I was a person who was going to do a bracketed tower. The "attractive" part
is that Rohn says you can go 30 feet or so above the bracket. In other
words, you can put up Rohn 25 at pretty low cost w/no guys. I never
understood the dual bracket thing either.
I even had a spot on the house where I installed the bracket at my roof
peak. I reinforced everything inside the attic, etc. Then I began thinking
about working on the tower 30 feet above that bracket. That's not the most
stable thing! And I never could find specs on what that 30 feet above thing
related to. How much wind load? What wind speed, etc. I wonder if that
sort of thing is just more suited to throwing up a single, vertical antenna
(such as some commercial user would have) as opposed to a ham station with a
large tribander and possibly other antennas as well.
While you certainly can have 30 feet of unguyed tower above a guy or other
attachment point and safely climb it - it is not the most stable. We had
two guys on my guyed tower about 25 to 30 feet above the first guy point who
put up everything before we attached the upper guys. And I worked up at
that point w/o the upper guys as well as I had to redo the guy bracket. But
this was all only temporary and the tower would move somewhat. You could
feel it and see it from the ground.
The idea of having antennas and a rotor unguyed and 30 feet above a house
bracket in a windstorm does scare me. The tower would probably move around
a lot! That's why I scrapped the house bracket idea and went with a guyed
tower with two guy points. It is very stable and solid.
I agree with Tom.
73,
Jon
NA9D
on 10/2/02 8:02 AM, n4kg@juno.com at n4kg@juno.com wrote:
> I am NOT a fan of house bracketing for several reasons:
>
> - Low support height
> - Tower vibration transfers to house as NOISE when wind blows
> - Possible damage to the house from strong winds
>
> As I have often preached, there is nothing STRONGER, SAFER,
> or more COST EFFECTIVE than a properly GUYED Tower.
>
> Short Towers can be guyed closer than the typical 80% radius.
> Even 50% to 60% is acceptable for light loads.
>
> Tom N4KG
>
>
> On Tue, 1 Oct 2002 "Jason Hissong" <jhisson1@columbus.rr.com> writes:
>> Hi guys,
>>
>> I am sure you get this question alot... and I have not found an
>> efficient way to search through the archives of the list to find the
>> answer. I am going to be installing a 25G at about 40 feet
>> (maybe 50 feet). The specs talk about bracketing the tower
>> at 15 and 30 feet. I cannot bracket the tower in both places,
>> I can probably bracket it at about 12 or 13 feet.
>
>> Does this effectively put the wind load specs for a 25G at 38 feet
>> (50'-12') or 28' (40'-12')? I want to put an MQ34R and an 11
>> Element Beam up.
>>
>> Thanks!
>>
>> Jason N8XE
>>
>
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-------------------------------------
Jon Ogden
NA9D (ex: KE9NA)
Life Member: ARRL, NRA
Member: AMSAT, DXCC
http://www.qsl.net/ke9na
"A life lived in fear is a life half lived."
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