I had a Force12 80M rotatable dipole which is a bit bigger (65 feet as I
recall). It used loading wires that also served as a support truss. The mast
ends of the truss were attached to the ends of a 3 foot piece of tubing
centered on the mast and was nominally about 3 feet above the boom. That
gives both vertical and some horizontal support. It survived the little ice
we get here once in a great while. I have seen drawings of that kind of
truss in ON4UN's book I think or perhaps it was the Physical Design book.
73, Larry W6NWS
-----Original Message-----
From: Stan Stockton
Sent: Thursday, January 28, 2016 10:18 AM
To: Rod Greene
Cc: towertalk@contesting.com ; Arnie Pfingst
Subject: Re: [TowerTalk] Klm 40m-1
A vertical truss does very little regarding survivability in wind.
It is absolutely necessary for survivability with significant ice load.
It can do more harm than good with ice if the vertical attachment point is
not high enough, due to compression. I've had booms and elements buckle up
between the top of the tower and the attachment point as a result of not
going high enough.
Stan, K5GO
Sent from Stan's IPhone
On Jan 28, 2016, at 8:11 AM, Rod Greene via TowerTalk
<towertalk@contesting.com> wrote:
Arnie,
I have one of the old KLM 40m-1 antennas and have used it for years. So
far it has served me well. They do not normally need a truss support. I
don't know what the wind specs are for your area of the country, but for
the northwest where I am located, no truss is needed, nor called for in
the documentation.
I don't think the antenna is anything to "write home about" but it is a
very good antenna for a shortened 40. And it handles and turns easily on a
tower. I have no idea how it would compare to a CushCraft.
73, Rod/w7zrc
From: Arnie Pfingst <arnie123@hotmail.com>
To: towertalk@contesting.com
Sent: Wednesday, January 27, 2016 9:37 AM
Subject: [TowerTalk] Klm 40m-1
I have a chance to buy a klm 40m1 rotatable dipole. The fella said its on
the ground. He said he "refurbished it" he has some paperwork for it and a
5kw balun with it. My questions are, does this antenna need a truss
support and how do I put one on, was this antenna really anything to write
home about. How does it compare to say... the cushcraft d40?Arnie
Sent via the Samsung Galaxy S®6 active, an AT&T 4G LTE smartphone
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