I have had over the years three different LM-470 towers, and there were some
significant changes. The most notable was the change from a single heavy
lift cable in the 1960's versions to double strung lift cable in later models.
(circa 1970). These variations are easily recognizable in the fact that the
lift cable had a moveable block pulley as part of the assembly. All had
positive pull down, and common drum mechanism. The later models using the
double
lift cables on each section are superior in that the load is more balanced
and less chance of binding. There were also changes in the fabrication of
tower end guides which appeared to be cost reductions as welded components
were
eliminated. My experience was the later versions resulted in more slop in
the fit and allowed more tower sway then the fitted and welded guides. There
may have been more changes, but the above I think were the most significant -
note cable sizes changed as well, and the double lift system used all the
same size cable diameter.
My tower now is a US HD-589, and I think much better built and rigged. The
level winding mechanism and the limit relays mounted at ground level is a
very nice feature.
Regards,
Norm W4QN
========================================================
Message: 3
Date: Sun, 23 Nov 2008 10:17:19 -0800
From: "Bob Selbrede, K6ZZ" <k6zz@ccis.com>
Subject: [TowerTalk] LM-470 Variations
To: towertalk@contesting.com
Message-ID: <49299e2f.9e.69d4.252229984@mail.ccis.com>
Content-Type: text/plain; charset="iso-8859-1"
Hello,
In researching specification information on the Tri-ex
LM-470 I see comments suggesting that the LM-470 has
undergone some design/specification changes over the years.
Does anyone have factual information regarding this? Are
there differences between the LM-470, LM-470D and LM-470E?
Is the Tashjian Towers LM-470E identical to the older Tri-ex
LM-470? Anyone care to shed some light on the subject?
Thanks!
73, Bob K6ZZ
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