Practical_Antenna_Handbook_0071639586

C h a p t e r 2 9 : T o w e r s 681
not, crosstalk between wires in the same cable can corrupt the beam heading information
used by the controller in deciding when to start and stop rotation.
Preowned Towers and Accessories
With respect to obtaining and installing used towers of any type, as well as tower accessories,
the author recommends proceeding with extreme caution—if at all! Tower sections
(especially those with hollow cylindrical legs) that have been in service or stored
outside for long periods may be weakened by hidden rust. However, it may be possible
with a sequence of complete sandblasting, inspecting, and hot-Âdip regalvanizing at
nearby reputable commercial businesses specializing in those tasks to restore tower sections
for your own use for less than the price of new sections plus shipping. Galvanized
guy wire and other “mission-Âcritical” hardware that is showing rust or black streaks
should simply be discarded. When replacing any original tower bolts, use only the
manufacturer’s recommended replacement parts. Bolts of a given size come in many
different strength ratings, and those you can find at your local hardware store are very
likely inadequate for your intended application.
Required Reading
Note that the title of this section is not “Recommended Reading”—it is “Required Reading”.
Installing a tower is no “Saturday afternoon and a keg of beer” picnic—it’s a
deadly serious project that requires massive amounts of reading and preparation. Failure
to do so can lead to death or permanent disability for you, your helpers, your neighbors,
or other members of your family.
At the very beginning of any antenna project, there are three kinds of source material
that a prospective tower owner absolutely must obtain and read thoroughly and
carefully:
• All relevant spec sheets and engineering documents available from the tower
and antenna manufacturers.
• The official building code, zoning, and wind speed requirements for your
county.
• Up the Tower: The Complete Guide to Tower Construction, by Steve Morris, K7LXC,
2009. Available from Champion Radio Products (www.championradio.com).
In addition, someone (professional engineer, local codes enforcement staffer, etc.)
associated with the tower project should have access to TIA Standard RS-Â222-ÂG and be
skilled in applying it to a specific installation. This document, available from the Telecommunications
Industry Association, is expensive and will typically be found only in
the offices of professionals who deal with towers and other antenna support structures
on a regular basis.