The four longest elements on my 7-60 MHz LP are about 45 feet with linear
loading. I did my own "engineering" on the array and wound up using
"plytubular" construction. The "center" tubes (+/-) are 10 feet of 1 5/8" OD
with three successively smaller tubes inserted tubes inserted. I used about
a foot of Extren solid rod for the break where the loading - 1/8" copper
tubing is attached and run back towards the boom. The center of the element
is supported by a 4 foot piece of 4 inch aluminum channel U bolted onto a 46
foot, heavy wall irrigation tube boom with overhead support. Everything is
either aluminum, SS, or Lexan except for the PVC tubing and U bolts that
clamp the elements onto their channel supports.
The design was for 100 mph wind, with 1/2 inch of ice, and a minimum of 10%
safety factor and has been at 100 feet with winds at least 85 mph, for
about 12 years, with no problems. One of the nice things re using the
plytubular design is that it helps keep the element OD and thus the wind and
ice load down.
Lots of aluminum, but I sleep well on stormy nights.
Gene / W2LU
----- Original Message -----
From: "GALE STEWARD" <k3nd@yahoo.com>
To: <lkeller73@roadrunner.com>; <towertalk@contesting.com>
Sent: Friday, May 25, 2012 10:55 AM
Subject: Re: [TowerTalk] 2 el 40m beams
I've have had very good luck with a reinforced Cushcraft 40-2CD. This
antenna was reinforced as per the W6NL mods and has survived ice, heavy wet
snow, and high winds. The newer model CC XM-240 can be strengthened in the
same way.
http://k7vc.com/402cd.html
Mine is at 72ft so yours would see a bit weather related stress at 100ft.
Also, if you want full length elements, ON4UN's 3 element 40M yagi looks
very strong. With a bit of computer modeling, you could re-configure it as a
2 element antenna. John's elements & boom are very robust.
GL with the project.
73, Stew K3ND
________________________________
From: "lkeller73@roadrunner.com" <lkeller73@roadrunner.com>
To: towertalk@contesting.com
Sent: Thursday, May 24, 2012 9:51 AM
Subject: [TowerTalk] 2 el 40m beams
Hello out there.
I'm at a loss as to what to replace a snow-damaged 2 el 40m beam with.
Everything I've found on-line doesn't really call out how strong the antenna
is.
Ideally, since most "gain" figures would be nebulous anyway, I want the
STRONGEST beam
out there since it's going on Bertha at 100 feet.
Any suggestions?
Lonnie
WA2AOG/W2RR
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