I am attaching three pdf files that at least Chris should get. Catalog page
copies from 1979 - W-51; and 1989 - WT-51. Notice the weight change from
355# to 417# for the same 20 foot section/tier type. This is presumably to
reflect the heavier tilt-over ready base that came standard.
Notice in the 1989 price list that they mention that the model:
quote-WT-52-unquote included the special version of the base that included
the longer ears that facilitated the use of the optional tilt-over accessory
(TA-51L). The old W-51 tower came with the rigid base (short ears) but you
could also just hinge it at the ground level by removing one of the two
bolts per leg on the two appropriate legs. I have an LM354-HD with the
tilt-over accessory. Also, there are additional ears on the modified tower
to provide the pivot points for the tilt-over feature a few feet above
ground. That added a few pounds to the weight of the WT-51 as well. I
surmise that the WT-52 is typo (see comments below about document review).
Notice that they did not change the cross section details except for the
model number and used the same era issue (A-5-72) of engineering drawing and
just changed the model numbers and deleted the 10 foot tier models. Notice
that they didn't change the specs on the top tier tubing dimensions. It is
apparent that the T means Tilt-over capable (at a point a few feet above the
base) which was not available in the original W-51 design.
It is interesting that both catalog cuts show the same wind load support
rating of 9 sq. ft. of antenna area in 50 mph winds. If the WT-51 could do
more why wouldn't they have modified their catalog to reflect that? I am
more inclined to believe (guess) that they recalculated and found that their
earlier design didn't provide the desired safety margin (or actual
performance) so they made a structural change to correct that deficiency.
But then why isn't such a presumed change reflected in the cross section
details (i.e., tubing wall thickness)? OR, is it a case where in-house sales
document review needed better (prior) engineering review or attorney review
before being published. Perhaps the design change coincided with the
tilt-over option availability or else they just snuck it into production
sometime along the way. This is all wild conjecture, of course. Hopefully,
someone with the true story and information will come forth to correct me.
Okay, now I found an un-sourced pdf (maybe I retyped the specs from notes
during a phone call and created the pdf) in my computer (attached for Chris)
with the (then) current WT-51 specs. It shows their (Tashjian)WT-51 to weigh
355# and is rated at 13 sq. ft. at 85 mph. I give up. I'm not going to
factor that into what I just wrote. I'll let someone else tackle that.
73, Kimo Chun, KH7U
Chris Merchant KA1LMR <ka1lmr@yahoo.com>
Subject: [TowerTalk] Tri-Ex W-51 Vs. Tashjian WT-51 specs?!
To: towertalk@contesting.com
Message-ID:
<1318994201.87148.YahooMailClassic@web65409.mail.ac4.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1
I have seen reviews with these towers lumped together but after some
research? after I bought a used W-51 and was told to use instructions and
specs on the current production of the WT-51.
?
Well I talked on the phone to someone at the company voicing? some concerns
after finding a picture of this tower? bent in half google WT- 51 tower
under images this was K8MN tower.? the guy at the company was shocked to see
there bent over tower.?
then the distinction? this was the older? Tower.
?
So, I asked for the specs on the older version of the tower? to see if it
was the same . He could find no specs for me? Just some diagrams parts list
dating back 2nd 1972 I didn't realize the towers dated back that far.
?
I confirmed one major difference the top section on the new towers are 1"
with 1/8 wall but the older W - 51 has only? a 16th wall!
?
If anyone has some Specs on the old tower? please pass it along the new
tower? specs says 14 sq ft? at 85 mph winds.? But the tech on the phone? is
saying with top section being 1/2? the wall thickness of the new? would? cut
the? the wind sq ft rating down to only 5-6 sq ft!? so before you put up a
large HF beams? and few vhf boomers if you have the older W 51 , I don't
think 1970's specifications have it rated at 14 sq ft @ 85 mph wind as the
ones are?
?
So I will be guying my "free standing" ?W - 51 at the top and middle
sections and a large frame bracket to the house?at the 20 Ft level , 2.5 x
2.5? x? 5 Ft concrete foundation? with re-bar cage? and pray it does not
come down.
I plan to have? 3 ele steppir with addon 8 sq ft total and 10 ft? steel mast
with antenna at the top? with 3 feet of mast in the tower plus the rotator.?
thoughts on whether this will be adequate and? specs on the older tower will
be appreciated.
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