IIRC, those towers were specifically designed for use with short boom
Yagis presented way too much torque on the tower.
Use it for the bottom of a 160 Meter vertical !!
73, Dick, W1KSZ
On Wed, Dec 7, 2011 at 9:22 AM, Mike Cizek <firstname.lastname@example.org> wrote:
> Bottom line.....the manufacturer wants $1400 (one thousand four hundred
> dollars) to provide the drawings. I have already told the guy we need to
> look at other options; all of which were more expensive, until we figured in
> the cost of getting proper drawings from Shelby.
> Thanks to everyone for the replies; we can close this thread and move on to
> something useful and more fun now :-)
> Mike W3MC
> -----Original Message-----
> From: email@example.com
> [mailto:firstname.lastname@example.org] On Behalf Of Gene Fuller
> Sent: Wednesday, 07 December, 2011 10:56
> To: Jim Thomson; email@example.com
> Subject: Re: [TowerTalk] HDBX-48 figures for 90 mph zone
> Bottom line, if the manufacturer can't, or won't, give you 90 mph data or at
> least the projected tower area and, taking into account the materials used,
> the maximum allowable restraining moment, then they probably know nothing
> about things like section modulus and moment of inertia and never did the
> calculations themselves, in which case I would have second thoughts about
> buying their tower.
> Gene / W2LU
> ----- Original Message -----
> From: "Jim Thomson" <firstname.lastname@example.org>
> To: <email@example.com>
> Sent: Wednesday, December 07, 2011 7:24 AM
> Subject: [TowerTalk] HDBX-48 figures for 90 mph zone
>> Date: Wed, 07 Dec 2011 00:19:21 -0500
>> From: K8RI <K8RI-on-TowerTalk@tm.net>
>> Subject: Re: [TowerTalk] Fwd: HDBX-48 figures for 90 mph zone
>> To: firstname.lastname@example.org
>> Message-ID: <4EDEF759.email@example.com>
>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>> On 12/6/2011 11:13 PM, HansLG@aol.com wrote:
>>> In a message dated 12/6/2011 4:43:51 P.M. Eastern Standard Time,
>>> firstname.lastname@example.org writes:
>>> As I recall wind pressure "on a flat surface" at 70 mph is 20.6 lbs/sq
>>> so if the tower is rated for
>>> 18 sq ft at 70 mph, would it be too much of a stretch to say to the
>>> board that since wind pressure at 90 mph is 34 lbs/sq ft, by simple
>>> the tower should be good for 10.9 sq ft at 90 mph ?
>>> Gene / W2LU
>> Regardless of wind area isn't there a boom length limitation on both the
>> BX and HDBX series?
>> Roger (K8RI)
>> ## yes, I think they reduced it to just 10' years ago..and sales
>> Just fudge the ant wind load a bit, and perhaps 'take out' one section on
>> Then when u install it, add the extra section back in. IF you ever did
>> hit it with
>> a 90 mph wind, and a big ant, ur gonna be in for an eye opener. That
>> thing about
>> 70 mph = 20.6 sq feet. That's from 1976. 222- REV-D. It's now REV G !
>> A Trylon T-500, 72' tall..is good for 22 sq feet @ 70mph....but only 6 sq
>> at 100 mph. The tower itself will eat up all the windload. Toss in any
>> you can kiss it goodbye. I wonder if the factory will even give you a
>> rating for 90 mph ?
>> Jim VE7RF
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