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[TowerTalk] Cal-Av 2D-40

To: "Tower" <>
Subject: [TowerTalk] Cal-Av 2D-40
From: "Dick Green WC1M" <>
Date: Wed, 26 Mar 2008 15:24:41 -0400
List-post: <">>
Hi. I'm considering buying a used Cal-Av 2D-40 2-element 40m beam and would
like to hear some opinions on performance and installation.


I'd like to hear from any owners/users on how the 2D-40 compares with other
40m monobanders. The beam will replace a 40-2CD at the top of a 110' Rohn 55


I'm also interested in how the beam has held up mechanically, though I
wouldn't expect many complaints: I participated in assembling the antenna in
question and I'm familiar with the very rugged design and construction (it's
survived a variety of hostile weather conditions here in Northern New


Most of all, I'd like to hear from those who have experience raising this
antenna. My plan would be to tram it, as I've done with other antennas on
the tower. It's quite a bit heavier (165 lbs) and has more wind area (16.5
sq ft projected) than the largest antennas I've put on the tower (4-el
SteppIRs @ 110 lbs and 10 sq ft), and is way bigger than the 40-2CD it will
replace. We use a wire-rope tram with trolley and an electric capstan to
haul the antenna, which helps a lot. There's 15' of tower above the top
guys, so the tram line can be connected to the tower instead of the mast and
back-guying isn't an issue. Once the antenna reaches the tower, it has to be
hauled up to the mast with a come-along. How well the antenna is balanced
will greatly affect how easy it is to handle during this step, so I'd like
to hear about that. I'm wondering how hard it may be to maneuver a heavy
antenna with a couple of 70' elements, and whether I need to use a
professional installer for this job. For reference, I probably wouldn't
attempt to raise a full-size 40m beam (e.g., 250-350 lbs and 25 sq ft.) But
after tramming SteppIRs (four times) my sense is that this antenna may be
something I can handle. Would love some opinions on that from anyone who has
put up a 2D-40.


Finally, I'd like to hear about experiences with tuning the antenna. The
Cal-Av design requires somewhat more careful tuning than other antennas I've
owned, and the manual suggests it's rather sensitive to height and other
"stuff" in the vicinity. There are a couple of hairpin stub adjustments that
are supposedly within reach of the tower. With the antenna mounted just
above the top plate, are the stub adjustments close enough to the tower to
reach without dismounting the antenna? If the adjustments can't be made with
the stubs, then the antenna has to come down to adjust the element tips. I'm
hoping that won't be necessary. I'm curious whether the pre-set length is
generally sufficient.


73, Dick WC1M


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