[TowerTalk] Pier pin vs. burying in concrete

[Chuck O'Neal]

Thank you folks!
Interesting comments.  A good summary of concerns
regarding my original question can be found at:
http://www.qth.com/ka9fox/pier_pin_vs_embedded_base.txt
This was referred to me by another list member.   I asked
the question since I've been a pier pin user and now am
be putting up another group of towers.  Just wondered if anything
was new!  As an aside, I had a 3E 75 M yagi on 110' of
Rohn 45 for 8 years, a modified KLM beam, and it went through a 
100+ MPH hurricane (Gloria) and the tower twisted +/- 30 deg
at the top, and the pier pin, the flat plate on the concrete,
was moving +/- 10 deg or so...quite scary but the whole system
survived!  The plate on the concrete was sitting on a disk of 1/8"
thick SS (304) about 10" in dia.  This allows rotation at the base
which provides the degree of freedom necessary for the pier pin
approach to work, I believe.  The flat plate supplied by Rohn
I think negates the advantage when placed on concrete
unless one provides a "bearing" surface with some "give to it.   
73,
Chuck...K1KW


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