Date: Wed, 30 Jan 2019 13:55:41 -0500 (GMT-05:00)
From: Dave Thompson <thompson@mindspring.com>
To: towertalk@contesting.com
Subject: [TowerTalk] ATTention Tennedyne owners
<The beam is mounted about 9 feet below the 2 el 40 Cushcraft .
<The tower guy said with the 20 foot 2" .25 aluminum mast I used that the extra
spacing might cause the mast to bend. The 40 meter beam has an overhead strut
that uses up almost 4 feet of the mast so 11 feet was the most I could separate
the beams.
<73 Dave K4JRB
## so which is it? Is the Tennedyne 9 feet below the 40m yagi.... or is
the Tennedyne 11 feet below the 40m yagi ? How much mast is inside the
tower ? How many thrust bearings are used ?
How far above the top of the tower is the Tennedyne mounted ? What rotor
are you using ?
## Did you run the load on the mast calculator ?? Installing a 40m yagi 9
to 11 feet above the top of the tower is no small windload. A 2 inch OD x
.25 inch wall aluminum mast is not strong to start with.
Think of the portion of the mast above the top of the tower as a long torque
wrench. Then the 40m yagi ..in a wind, creates the load. This is all
easily calculated out on mech mast software. Then at least you will
know the max windload the mast can handle...before it snaps..just above the
top of the tower.
Jim VE7RF
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