The thing you might want to do is employ a P.E. (Professional Engineer) to
do the calcs for you that tells you what heights on your particular tower
yields a safe wind load for you situation.
I am relatively sure that U.S. tower can provide you with a name of a P.E.
that could do these
calcs for you... I do not think, due to liability issues that any tower or
antenna manufacture or vender is going to tell you how to "Safely" overload
your tower.
But then the money you will most likely have to pay the P.E. could have been
used to buy a tower that would have been rated to keep your antenna safely
at max height and wind load......
73, Dennis N6KI
Sandy Eggo
On Sun, Jun 22, 2008 at 12:33 PM, Bernard <wtrone@comcast.net> wrote:
> Ron: I am currently in the process of putting up a U.S. Tower MA-850
> with the rotor base and will be putting a 3 element SteppIR with the 40/30
> modification on top. At a 70 mph wind and the tower fully erected, I will
> surely be in an overload condition if there is no margin in the
> specifications. I went through a lot of consideration, emails, and
> conversation before I selected this tower because of the 70 mph wind load
> limitations.
>
> I think that you will find that the tower companies will be very
> reluctant to talk about margin and overload. I tried, several times, and
> was NOT able to get that information. If anyone has that information, I
> would sure like to get it.
>
> My solution? I bought the fully motorized tower. I plan to keep it
> retracted unless I am operating. While I was not able to get actual wind
> load numbers for the retracted tower, I am lead to believe that it is much,
> much higher than the SteppIR will present, maybe by a factor 5 or more.
>
> Good luck getting your tower up.
>
> 73s,
>
> Bernard, WA4OEJ
>
>
>
>
> ----- Original Message -----
> From: w4lde
> To: TowerTalk ; SteppIR Yahoo Group
> Sent: Sunday, June 22, 2008 10:39 AM
> Subject: [SteppIR] Advice on Tower
>
>
> I recently have moved to a new home, SW of Atlanta and have a SteppIR
> 3-element with the 30/40 add on sitting in the garage waiting on a new
> tower.
>
> I have approval from the HOA and County to erect a Tower, home deed was
> filed with modifications to allow a ham radio tower and antennas.
>
> Although no specific restrictions on height or style are place on me by
> the HOA or the deed modifications, when I started the process
> I thought a US Tower MARB-550 would look very neighbor friendly and be
> easy to get buy in's by all.
>
> I already have a base for the tower in-place but I am a little concerned
> as to the ratings for the MARB when comparing a TX-455 style.
>
> My Counties wind rating is 70MPH, we have already seen 50MPH gusts
> during a thunderstorm recently.
>
> The tower is rated at 9 sq/ft at 70 MPH and 61#'s weight, the specified
> wind load by SteppIR is 8.1 sq/ft. at 58#'s I would elect to use the
> rotating n base thus keeping the rotor at the bottom of the tower and
> reducing the extra weight and little load.
>
> Now the questions?
>
> 1. Since I am almost right on top of the spec's, wind load and weight,
> should I abandon this Tower selection.
> a. As it now stands I have a 3'-6" x 3'- 6" x 6" concrete base with
> rebar and mounting bolts per the US tower spec's
>
> 2. Is there a way to adapt any type of rotating guy device to this
> type of tower?
>
> 3. I would also like to hear from SteppIR - US Tower users with similar
> setups.
>
> Plans are to erect the Tower some time in mid September or early October
> depending on deliver time so I need to get the order underway.
>
> Maybe I can improve on the ratings by not keeping the Tower raised to
> the maximum height unless I am chasing some DX expedition or am I
> dreaming?
>
> 73's de
>
> Ron W4LDE
>
>
>
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