100+ winds in Phoenix
AA7NO@aol.com
AA7NO@aol.com
Fri, 16 Aug 1996 00:52:17 -0400
Dateline --- Phoenix, AZ
Last nite, August 14, hams in Glendale, AZ, a suburb of Phoenix, were
surprised to
receive up to 115 mph winds in a very short time frame!
Here is a list of the towers and antenna systems, how they were affected, and
what
in the future could be done to make the survival rate better.
contester #1.... Rohn 25g at 100' with stacked beams on 40m, 20, 10m
mast pipe bent at 45 degree angle, great for
moonbounce, all
to come down and replace mast pipe. 3 sets of 3/16"
rohn guy wire
,,, top and bottom set tension okay, middle set at
60' were
EXTREMELY loose, maybe 3' sag in the middle? One
12"
turnbuckle was 2 threads from becoming completely
undone on
the middle set. Needed to have safety wire per Rohn
installed.
Rohn 25g 68' foldover tower... with 4 el quad on 30'
boom about
6' above the top of tower. Mast pipe did NOT bend,
however the
Tailtwister did actually BREAK in two!! No Joke!
the clamps were
still on the mast pipe, now at a 30 degree angle, the
gear portion of ]
the rotor still mounted to the accessory shelf!
Amazing!!
Cure? maybe another accessory shelf above the
rotor.... the top
section is a flat plate with a thrust bearing, but
not enough room to
mount a second thrust bearing above the rotor. Guy
wires okay on
this tower although still needed safety wire on
turnbuckles.
Contester #2 70' Rohn 25G with 2 el HyGain 40m antenna and Mosley TA-36
slight twisting of the HyGain elements, the driven
elements slightly
bent. Remember these were 100+ mph winds...
Elevated Guy post
bent about 15 degrees, no back stay for this post.
Taking up slack
today in the top set of 2 guy wires, noticed that the
guy wire was
almost flat, each strand, rather that the usual round
7 strand stuff.
Asked the owner, " what is the make of this guy
wire"? he said,
"It's regular Rohn stuff"!! I looked futher up the
guy wire (from the
turn buckle at the elevated guy) and by golly, it WAS
regular Rohn
3/16" guy wire!!!!!!!!! The stuff had actually
STRETCHED and was
now almost 3/32" guy wire, flat!! AMAZING! In my 25
years of
putting up Rohn tower I have never seen this. Cudos
to the Engineer
who the owner had hired to do the specs on this
tower! Remember,
this was 115 mph (measured) winds! and it survived
the storm!!
However, when we went to temp tighten up this top set
of guy wires,
it must have twisted the wire over 20 turns, no
kidding, as the guy
wire went round and round before it would stop!
Again, not safety
wire was installed! Owner says it will be this time
though!
contester #3 Heights 55' crank-up tower with Th-6, Cushcraft 3el WARC
beam,
Cushcraft 2 el 40 m and 2m antenna on top. Cranked
down to about
45'. Tower collapsed at base, fell over block fence
with much
damage and onto the street. Every antenna lost and
of course the
tower way beyond repair.
the Future, every guyed tower MUST have the safey wire on ALL the
turnbuckles,
we must follow the manufactures instructions to the letter!!
Oh yes, all towers were in a 3 square mile area.. how did mine do? Well,
good fortune held that I had taken down all antennas 2 weeks ago for
overhaul, safety wires on all guys, so no damage on tower. However, window
blew out in living room
on top of XYL's doll collection, but that's another story....