Rohn 25 and 20 stability

[Dave Hockaday]

>>Any opinions or
>>experience on using [Rohn 20G] sections at 120-130 ft with no load on
>top?
>
>Even a well guyed Rohn 25G tower feels pretty limber at 130 feet.  (The
>tallest 25G tower I've climbed personally is 160 feet.)  Irrespective
>of Rohn's specs., I would not be comfortable in working on a 130-foot
>Rohn 20G tower, even with no load on it.  And I'm a risk taker, at that!  

Hi Bob and gang. I have a comment about the 130' rohn tower above. 

*- I have a 200' Rohn 25 tower in Clayton NC that has been up for about 15
years. It has a Sinclair 4 bay vhf dipole array on top fed with a run of 1
5/8" hardline, a diamond dual-band vhu/uhf repeater antenna sidemounted near
the top and fed with 1/2" heliax. There is also a 3 element lowband dipole
array spaced around the tower and fed with 1/2" heliax. During the UHF
contests it has had a number of 1.75m and 70 cm antennas installed between
the 150 and 200' levels. There are 2 repeaters and a remote base operating
from that tower.

So far, no problems (except an increasing # of annual lightning hits!). It
has stood through 2 hurricanes, and multiple near tornados etc...still
hanging in there. I have been on the tower many times over the years, and
usually with another climber. It does move around a little at the top, but
80mph sustained winds haven't phased it. 

*- I also have 100' behind my house with an A3S, 2ea. 13B2's, 6m Ringo, and
6 m 5 el yagi all topmounted. Sidemounted are: 10 meter sidemounted
vertical, 11 el 70 cm yagi, a 70 cm 3 el yagi, and a 5 el 2 m yagi.

*- I maintain 4 repeaters near Wendell NC that have all their antennas
mounted on a 150' Rohn 25 tower that's over 20 years old. It has a custom
top section allows 3 repeater antennas to all share the top, similar to
those seen at cell sites. It has a Diamond dual band repeater antenna on one
point, a Hustler G7-220 repeater antenna on another point, and a 16' tall 10
meter antenna for the 10 meter repeater on the 3rd point. It has an 11el
Cushcraft 70cm antenna side mounted for linking, as well as a vhf antenna
for NOAA wx reception. Multiple runs of 7/8" heliax feed the VHF/UHF stuff
as well as 1/2" hardline for the 10 meter repeater and link antennas. It has
stood the test of time like the first tower I mentioned, and is still very
solid to climb. 

Just north of here is a 180' Rohn 25 tower with a set of 6, 2, and 440
repeater antennas...all fed through separate runs of 7/8" hardline. It is so
solid to climb that you'd think it was 55! It, too, stood through hurricane
Fran, and not so much as a loose bolt. 

I guess I was just trying to point out that 25 is really pretty tough stuff.
I did install a tribander and monster 2 meter yagi on a 70' Rohn 20 a few
years ago, at the insistance of the owner. I didn't think it could take it,
but it stood throught the hurricane and no problems. It's been up about5
years. I'll also add that it felt about the same as a Rohn 25 from the top.
Just my $.02 :-)
 
73 es Merry Christmas!



73 de Dave Hockaday WB4IUY
Youngsville, NC
wb4iuy@ipass.net  
WB4IUY@W4RAL.#RTP.NC.USA.NOAM

http://www.ipass.net/~wb4iuy/
http://www.ipass.net/~hockaday/
http://www.ipass.net/~teara/
http://www.geocities.com/TheTropics/3349/
http://www.RTPnet.org/~fcarc/
http://www.RTPnet.org/~rdrc/



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