The difference on signal strength between a large pipe as and 18 ga wire is
likely a fraction of a db. So the design of the pole is for stability and
ease of erection not performance. The performance will be determined by
the ground system.
A very good choice for experimentation is spiderbeam 40ft pole. Seems to
last forever when attached at the bottom by bungee cords, without guys.
Costs a bit over $100.
I am using it now at a beach side on FL to support a 40 vertical and 160m
inv L. No problem despite high winds and the performance is excellent - due
to salt water.
Ignacy, NO9E
On Wed, Jan 1, 2020, 11:14 Gedas <w8bya@mchsi.com> wrote:
> HNY to all !
>
> I cannot think of a better time to start a new 40m phased vertical
> project then the dead of winter with snow on the ground (as usual I
> could not get to it during the summer or fall).
>
> Anyway, I have drawn up two possibilities for a pair of 33' self
> supporting verticals. Both start out with a 10' length of EMT but one
> choice starts out with a larger dia then the other before I switch over
> to tapering aluminum sections.
>
> A) Starts out with a 10' length of 1-1/4" EMT followed by tapering 5'
> sections of aluminum tubing (4' long exposed, 1' inside the previous
> lower section) until the very top length section which will be 3/4" OD
> dia. These will be standard DX engineering aluminum tubes.
>
> B) Starts out with a 10' length of 1-1/2" EMT, then a 5' length of
> 1-1/4" dia of EMT (4' long exposed, 1' inside the previous section of
> EMT) then followed by tapering 5' sections of aluminum tubing as above.
> The only difference being this choice would end up using 1" aluminum
> tubing as the very top piece.
>
> So the obvious difference between the two are that choice A) uses just
> one length of thinner EMT and overall thinner aluminum tubing sections
> to the top while choice B) uses 2 lengths of larger dia EMT and then
> larger dia aluminum tubing to the very top.
>
> I do not have the software to analyze choice A) vs. choice B) in a high
> wind situation. I am uncertain if the stronger, larger dia tubing with
> it's higher wind load will be a plus or a minus in the end to it's
> overall strength. Any thoughts or comments on which one will survive
> better during heavy wind conditions? TU
>
> Gedas, W8BYA
>
> Gallery at http://w8bya.com
> Light travels faster than sound....
> This is why some people appear bright until you hear them speak.
>
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