[TowerTalk] Class 2 and Class 7 Poles
doc
kd4e at arrl.net
Mon May 17 18:08:50 EDT 2004
I have been told that anywhere lightning is common a wood pole
is a very bad idea because the antenna(s) and cables provide
the only path for discharge of energy whereas a steel tower
siphons off the energy and can limit antenna and coax exposure.
Perhaps someone on the list has better info?
Here in West Central Florida one has to worry about billions
of voracious termites chewing down the post overnight! ;-)
73, doc
RICHARD BOYD wrote:
> It's completely practical. Comparative cost depends on your ready
> availability of cheap or free poles versus cheap or free tower sections, and
> cheap or free installation.
>
> First, telephones poles are completely acceptable, in that height range, or
> any height range that you can acquire sound poles (available taller on the
> West Coast U.S. than on the East Coast) and used to be much more common for
> hams than they are today -- back in the days when commercial towers were not
> so widely available but poles were.
>
> Telrex used to sell, for $175 apiece the last I knew, a "telephone pole
> lash-up," of which I have several, "bought new" from them, that are steel
> angle formed into L-shapes, then with "all-thread," threaded rod, with
> washers and nuts, to hold the assembly together, bolted through a pole and a
> couple steel plates to form a rotator shelf and thrust bearing "shelf."
> These can be quite strong, I believe. Old Telrex literature should give
> their opinion on what they can hold. But, I recall their brochures showed a
> drawing of that setup holding a "Christmas tree" of 20/15/10 3-element
> yagis, something like that. So, telephone poles will definitely work and
> are pretty (very?) sturdy. I've never heard of one snapping off in high
> winds from all the antenna load on top. Intuitively, I think when the winds
> are really strong it's more likely the mast will bend than that the pole
> will break.
>
> So, one advantage: High antenna/windload capacity. I've never heard it
> stated as square feet allowable at the top, as our towers commonly are, but
> maybe someone has done that sort of study or one of our towertalk readers
> has info on it.
>
> Another advantage: It's a "self supporter," so the footprint on your
> property is less than a guyed tower.
>
> And another advantage: A lot of people might be used to seeing telephone
> poles around, holding your backyard or barnyard security light, etc. and may
> hardly think of it as a "tower," and may find it less noticeable and less
> objectionable than a "real" tower.
>
> Practicality speaking...I have started chatting with telephone pole crews
> when they're working in my vicinity and volunteering to take poles when they
> have "pulls" to get rid of, etc. -- and they always ask what size I need or
> want. I say, "Any size," because, I tell them, I can use them for a pole
> barn, a bridge across a small stream, or if I have a long enough one, for an
> antenna support. The point is, if you can scrounge successfully, you might
> be able to get a free pole or two. And, I've heard it said that sometimes,
> "for a case of beer" the pole guys will drill the hole and install a pole
> for you. Or not. Maybe it'll take $100. Whatever, you may find it's a lot
> cheaper than putting up a tower.
>
> But, the tower option is the flip side. If you have friends with extra
> tower that they'll give you, that can be comparably cheap, and something
> like Rohn 25 is relatively easy for us non-professionals to put up, you
> don't have to fabricate some Telrex-type "telephone pole lashup," to
> transition from pole to mast, etc. The towers are already designed for
> these, have rotator shelves available, etc. Most of us probably would want
> the telephone pole crew and truck to put up the pole for us, but could do a
> 40-50' Rohn 25 ourselves or could find a ham buddy with experience doing it
> who could supervise the tower installation.
>
> For the telephone pole, you'd also want to get pole steps for it. I
> question the wisdom of us amateurs trying to learn how to use spikes to go
> up and down to work on antennas. Aside from the safety issue of really
> being able to learn how to use them right, it'd just be a hassle compared to
> climbing a tower. But real pole steps would be acceptable, though I doubt
> most hams would consider them as convenient as a tower, to climb. The
> telephone pole guys should be able to get you steps too. I don't know. Way
> back in the past when I wanted some I had trouble finding any but did
> finally get a bunch, at the invitation of W3GRF (now SK), that were out in
> his woods under about a foot of leaves and debris. And, the labor of
> putting steps in a tree or pole is significant -- another reason to consider
> tower instead. And, climbing and working on pole steps for a while can be
> more uncomfortable than on a tower, where changing position and level, etc.
> is easier -- more options on a tower. On a pole with steps you tend to be
> limited on where you can stand, what position you're in, etc. If it's a
> simple antenna, installed with reliability and low maintenance in mind, etc.
> you shouldn't have to go up very often.
>
> SUMMARY:
>
> So, in my opinion, poles are excellent, heavy duty, relatively short,
> antenna supports. They can also be lower profile, small ground footprint,
> and may be readily available for the gregarious ham, or the ham who has
> friends in the telephone pole installation and removal business. If you
> have a buddy who says he has a pole or two or three and will come over and
> put 'em up for a case of beer, that's a good offer. The pole installer
> should be able to drill the hole as part of his work.
>
> Towers can go higher, hams are more likely to be able to install them
> themselves with a couple buddies, and have convenience advantages in some
> ways, though are going to tend to be more noticeable and have that
> triangular footprint on your property. If you have a buddy who has a 40 or
> 50 or 60' tower he wants to give you and will help you put it up, that's a
> good offer. You'll have some expense for concrete, you'll have to dig the
> hole yourself or have a buddy with a backhoe do it, or pay to have it dug.
>
> Not an expert, just a ham who's tried to keep his ears open, yaknow? 73 -
> Rich, KE3Q
>
>
> ----- Original Message -----
> From: "Alan AB2OS" <ab2os at att.net>
> To: "towertalk reflector" <towertalk at contesting.com>
> Sent: Monday, May 17, 2004 2:28 PM
> Subject: Re: [TowerTalk] Class 2 and Class 7 Poles
>
>
>
>>How practical is it to use a 50' (or 60', if available)
>>utility/telephone pole as a support for something like a 3-el. SteppIR?
>>And how would the installed cost compare with a typical steel tower of
>>the same height?
>>
>>Alan AB2OS
>>
>>
>>On 05/17/04 02:10 pm Doug Faunt N6TQS +1-510-655-8604 put fingers to
>>keyboard and launched the following message into cyberspace:
>>
>>
>>>According to -The American Elecricians' Handbook-, the standards are
>>>from ANSI, and the 10 classes are classified by the circumference at
>>>the top and at a point 6 feet from the butt.
>>>
>>>Class 2 is 25 inches minimum top circumference, and the figure for 6
>>>feet from the butt is dependent on the type of wood and the overall
>>>length.
>>>Class 7 is 15 inches at the top, and 29.5 toward the butt for
>>>Creosoted Southern Pine, 50 feet long.
>>
>>_______________________________________________
>>
>>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.
>>
>>_______________________________________________
>>TowerTalk mailing list
>>TowerTalk at contesting.com
>>http://lists.contesting.com/mailman/listinfo/towertalk
>>
>
> _______________________________________________
>
> 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.
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
--
Thanks! & 73, doc kd4e
West Central Florida
Drake, Heathkit, Kenwood, TenTec, Yaesu
Radio Life: http://www.gospelcom.net/twr/
Linux-Incompatible hardware is defective!
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