FYI. I note that the 15m/50' high unit price is not exactly cheap at a
discounted $2500 when a Tyron is about $1300. And, the correction on the
wind rating changes from a published 19 sq ft to 5.7 sq ft! Just a tad off,
I'd say. I am no longer interested in this product for my application.
Al
-----Original Message-----
From: steve/michele higbee [mailto:higbee@pe.net]
Sent: Monday, January 26, 2004 9:04 AM
To: Al Toothaker
Subject: Re: Price and availability request
On 1/25/04 9:19, "Al Toothaker" <n6ta@arrl.net> wrote:
> I have been planning a new tower and have local officials that are pushing
> me to a non-guyed tower. Yours may be the trick based on the method
> available to raise the antenna.
>
> My need would be for the short one, 15m high. I would like the price for
> the tower and all of the needed parts for use, construction and
> installation, please. Also, please indicate lead-time and approximate
> shipping costs to a residence in 95006, Northern California. Call if you
> prefer.
>
> Best regards,
>
> Al, N6TA
>
> 408-314-8301
>
Dear Al,
Thanks for writing.
Lead time is really short as we have a 15 in stock. Will need to get back
to you on shipping. Will-call may be practical for you. A 15 weighs about
half-ton and will fit in bed of pickup.
We do not supply the foundation rebar cage. Anchor bolts, however, are
included.
All fixtures for erecting the tower are included.
Current price list and other info is appended.
We are reducing inventory and have discounted prices on 33, 41.4, and 50 ft
towers. $1895, 2195, and 2495, respectively.
Our yard is in Cherry Valley, in south California, about 20 miles east of
San Bernardino.
Please note: the website is incorrect on the antenna area rating. Should
be 5.7 SF. Antenna area really is not an issue, as you may stand on solid
ground and quickly and easily lower a very large array, even during a strong
wind storm.
Regards,
Steve Higbee KD6JDM
cc: WB6MSS
One-Man Towers? USA
Banning, Calif.
P.S. Please check our website <www.onemantowers.com>
Price list, effective Dec. 1, 2003
All Prices in US Dollars
Shipping charges not included
33 ft. (10-mtr) $2828
---------------------
41.4 ft (12.5-mtr) $3233
---------------------
49.7 ft (15-mtr) $3773
---------------------
58 ft. (17.5-mtr) $4313
---------------------
66.3 ft (20-mtr) $4853
---------------------
74.5 ft. (22.5mtr) $6203
Special order
---------------------
82.8 ft (25-mtr) $7283
Special order
----------------------
Add $938 for the optional electric winch.
Purchases subject to applicable sales taxes.
Purchases may be subject to duties for deliveries outside the US.
Prices subject to change at any time.
NOTES:
1. Actual tower height is to the top of the mast which holds the antenna.
For example, a 10-meter tower consists of three 2.5-meter tower sections,
plus the mast, making a total height of 10 meters.
2. The buyer is responsible for obtaining all local or county building and
tower permits.
3. The buyer is responsible for removing the tower from the freight truck
(if applicable) when it is delivered. The weight of each tower section
ranges from about 170 pounds to about 270 pounds. Please arrange for help
in off-loading. You will need a tool to cut the steel strap which binds the
load.
4. Towers are drop-shipped from Australia to the most practical U.S. Port of
Entry nearest you.
You may have your tower shipped from the designated Port of Entry, but we
suggest that you pick up your tower at the designated Port Of Entry.
----------------------------------------------------------------------------
Australian engineering data comes with the towers. It is valid here in the
states, but must be endorsed by an engineer licensed in state where tower is
to be erected. Engineering may not be needed in every case, or if no permit
is required.
Here is a sample.
Engineers report - Facet Structural Engineers, Queensland.
We have checked the 50' (15-mtr) tower (5 x 2.5 meter sections plus 2.5
meter aerial support post on top) based on AS 1170.2 (the Australia Wind
Code) and AS 4100 (Australian steel code), Grade 450 (65,000 psi) steel for
the tube and 4.6 Grade for the M16 bolts.
We have checked it for maximum wind speed for aerial up and aerial down,
assuming the aerial has the same wind area as a 2.5 meter section of tower
as a worst case estimate.
The table below summarises maximum design wind speeds from our design check,
expressed as aerial up or down, Terrain Category 2 or 3 (i.e. in open,
relatively treeless terrain such as farmland, or suburbia/ forested
terrain).
It is also expressed as either permissible stress design wind speed (called
ASD - allowable stress design, in the USA) or ultimate limit state design
wind speed (called LRFD - load and resistance factor design in the USA).
ASD is gradually changing to LRFD in the USA, so I'm not sure which one your
engineer would be more conversant with.
We are ahead of them in this and made a similar change in our wind code in
1989 and in our steel code in 1990.
Maximum design wind speed:
ANTENNA IN OPERATING POSITION
ASD TC2 / TC3 (terrain categories 2 and 3)
KPH: 137 / 162
MPH: 85 / 100
LRFD TC2 / TC3
KPH: 167 / 194
MPH: 103 / 120
-------------------
ANTENNA LOWERED
ASD TC2 /TC3
KPH: 166 / 194
MPH: 103 / 120
LRFD TC2 /TC3
KPH: 202 / 239
MPH: 125 / 148
------------------------
In both cases the load is limited by the HD bolt capacity, but the 40 x 40
SHS (1.57 x 1.57 x 0.118 inch square tubing) capacity in the base section is
very close to the HD bolt capacity for the aerial down condition.
Maximum wind speed for TC2 is lower than TC3 because TC2 is smoother
terrain, thus less wind energy loss in turbulence and thus higher wind
pressures on elements projecting into the air-stream for the same wind
velocity.
Our wind code is based on a peak 3 sec. gust with a 5% likelihood of being
exceeded in a 50 year return period.
US wind loads are derived from a 1 minute average gust intensity as I
recall.
I don't have a US wind code, so I'm hoping your engineer in the US can use
the wind speed data above and interpret it in terms of the US wind code
requirements. In expressing the outcome in wind speed terms, it should be
code independent, as a safe wind speed (ASD) should be directly usable.
This should answer the "wind rating " question and the "shear rating of the
base" question. The shear strength of 8M16 4.6/s bolts is about 25 times
greater than the base shear force from the wind loading.
The HD bolts fail principally in tension from overturning forces from the
tower, not shear forces, and you have a sizeable reserve.
Regards.
Ron Blackwell
Facet Structural Engineering Consultants.
Suggested MINIMUM amounts of concrete in the foundation.
10 meter (33 feet)-----2772 kg (6098 lbs)
12.5m (41 ft)------- 3916 kg (8615 lbs)
15m (49 feet)------- 5640 kg (12,407 lbs)
17.5m (57.2 ft) -------7676 kg (16,887 lbs)
20m (66 feet) ------- 10,026 kg (22,057 lbs) *
22.5m (73.8 ft)------- 12,688 kg (27,914 lbs) *
25m (82 feet) ------- 15,664 kg (34,462 lbs) *
(* these towers employ extra heavy duty lower sections and heavier hold down
bolts)
A cubic yard of concrete commonly weighs from 3500 to 4000 pounds, depending
on the mix. Please consult your local ready-mix plant.
Besides the amount of concrete, local codes and soil conditions will
determine the details for your foundation.
In addition, you will have to provide a rebar framework which meets your
local code for tower installations.
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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