I had heard that Rohn rotated the leg flanges but I did not know of the
other differences. I wondered why it was rotated, perhaps the strengths are
different and it was done to avoid mixing the versions. Does anyone know
when this change occurred? I purchased my Rohn 65 in the 90's and I believe
that it is the latest version.
If I wanted an 80' self supporting Rohn tower I would look at SSV.
John KK9A
Byron Tatum W5FH
Hello- I am looking at around 200' of much older tower, from commercial
service that has orange/white paint scheme on it. It appears identical to
Rohn 65G in construction -- the leg size, zig zag brace size and pattern,
and flange square dimensions. However, looking closer, these differences
appear when comparing this older tower flanges with a marked 65G specimen:
1. The flanges on older tower are 1/2" thick (Rohn 65G is 5/8" thick)
2. The flanges on older tower are oriented differently -- they appear to
be rotated 45 degrees as compared to Rohn 65G specimen. 3. I cannot find
any part number stampings on this tower -- the Rohn 65G has part number
stampings. 4. The flanges on this older tower are drilled in center to
allow drainage. The hole size is around 5/8" on some sections and around 1"
on other sections 5. The weld around tower leg on flange top on this
older tower is not as "heavy" as the weld on Rohn 65G specimen.
Here are my concerns - I wish to use some 65G tower as a self supporter
adjacent to my shop, in vicinity of 70 to 80 feet high with light antenna
load. I plan to install it according to Rohn's drawings for this
application, per the highest wind load specs/strongest installation. This
would be a substantial base and lots of concrete/rebar. But I want to know I
have the strength of 65G. I am trying to find out the particulars of this
tower. Some knowledgeable folks have stated that it is Rohn, just an earlier
version of 65G that was redesigned at some point and thus the flanges
rotated on newer design to prevent mixing.
The one thing that concerns me is the welding of the legs to the
flanges. It is said that Rohn welds the legs to the flanges both inside and
outside. I noticed on Rohn 65G that the hole on flange is much larger. Does
Rohn actually punch out a hole in the 5/8" thick flange plate and slide it
over the leg, thus allowing this double-welding? This point here is the main
thing in my mind in comparing the strength of the two different towers --
the older tower has thinner flanges and the flanges obviously are welded to
legs only on the topside of flange due to small drilled holes as mentioned
earlier.
Can anyone fill me in on this please.Byron W5FH
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