[TowerTalk] 2 el 40m beams

[Gene Fuller]

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 at yahoo.com>
To: <lkeller73 at roadrunner.com>; <towertalk at 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 at roadrunner.com" <lkeller73 at roadrunner.com>
To: towertalk at 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
_______________________________________________



_______________________________________________
TowerTalk mailing list
TowerTalk at contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk