[TowerTalk] Antenna spacing question

[Don Moman VE6JY]

> I have a TH6 right at the top of my tower and a Cushcraft A3WS about 9 feet
> above that. I have a serious tower and rotator and am going to add a 2
> element 40 meter yagi this Fall. Can someone give me an idea of spacing
> requirements between the three antennas? I have a 20 foot mast, 10 feet of
> which is currently inside the tower. I plan to move up the rotator shelf.
> Right now the mast only sticks up 10 feet. It's 1/4 wall Schedule 80. I'd
> rather not side mount the A3WS lower down the tower as a local suggested.
> Thanks for any guidance. Rick VE9HF
>
>
Hi Rick;

If your QRZ picture is current, it looks like the tower is a 48' self
support Delhi  (Canadian "version" of the Rohn BX but not as strong)  I'd be
nervous enough with the current windload, let alone adding more mast and
antenna.  My Delhi catalog rates the Heavy Duty 48 foot tower at 9 sq feet -
that's at the top of the tower, not 9 to 15 feet above, which increases the
load on tower way past the danger point, in my opinion.  The manufacturer
states: "guy wires must be used for larger loads".   The torque that your
installation exerts on the tower with the rotor mounted where is it will
also hasten the failure, likely at or near that level.  Conventional guying
(as opposed to torque brackets) will not do much to limit the twist.

73 Don
VE6JY