for Storm Survival, Long Term Reliability and Safety Design, Installation and Maintenance of Antennas, Towers and Rotators By Frank Donovan W3LPL for Storm Survival, Long Term Reliability and Safety Dayton 2013

A Typical Tower and Antenna

Your Tower in its Environment Dayton 2013

Tower Sections Design and Construction Adequate load capacity for current and future use antenna loads especially unbalanced or unidirectional loads coaxial and other cables Adequate load capacity for local environmental conditions wind loads (especially severe site specific conditions) ice loads (especially severe site specific conditions) Unidirectional or unbalanced ice and wind loads Corrosion protection including site specific conditions Beware of used or corroded tower sections with tubular legs Dayton 2013

Tower Sections Maintenance and Inspections Inspect all tower sections one year after installation then at least once every three years after every serious storm after any structural damage to the tower Check plumb and twist of the tower Pay special attention to damaged, loose, missing or corroded: diagonal and horizontal trusses, welds and hardware especially at and close to the guy attachments Beware of used or corroded tubular tower sections Regular inspections are key to safety and long term tower and antenna survival Dayton 2013

Tower Base Design and Construction Use the manufacturer’s recommended design provide adequate depth for local frost conditions The top of your foundation should be at least six inches above grade Towers with tubular legs embedded in concrete require careful attention to reliable drainage during construction each leg must drain into gravel at bottom of the foundation concrete embedded tower sections are a risky practice in salt air or corrosive industrial environments Your tower base must provide reliable drainage for tubular tower legs Dayton 2013

Tower Base Maintenance and Inspections Inspect at least once every three years Pay special attention to: corrosion at the tower-to-concrete interface standing water on the foundation dirt and debris accumulated on the foundation settling and cracks Dirt and debris accumulation on your tower foundation can lead to catastrophic tower failure Dayton 2013

Guy Anchor Design and Construction Guy anchor failure is one of the most common causes of catastrophic tower failure determine if you have corrosive soil conditions in your area adequate guy anchor depth for local soil conditions use only heavy duty galvanized, forged hardware use tower manufacturer’s recommended guy anchor design corrosive soil require professional guy anchor design elevated guy anchors require professional design Never use light duty home owner grade hardware Dayton 2013

Guy Anchor Maintenance and Inspections Inspect at least once every three years dig down at least six inches to inspect for anchor rod corrosion missing hardware loose hardware corroded hardware Anchor rod corrosion is a very serious threat to tower safety survival Dayton 2013

Guy Wire Design and Construction Use heavy duty galvanized, forged hardware Use tower manufacturer’s recommended guy wire size smaller guy wire risks catastrophic tower failure heavier guy wire reduces the tower’s load capacity Tension guy wires to 10% of breaking strength less than 7% risks galloping guy wires and excessive tower flexing in the wind greater than 15% risks guy wire vibration and reduced tower load capacity guy wire vibration dampening hardware may be needed Never use light duty home owner grade hardware Dayton 2013

Guy Wire Maintenance and Inspections Inspect three months after installation Inspect at least once every three years Inspect after all serious storms Check guy wire tension (7-15% of breaking strength) Check for: damage from rubbing of chaffing of guy wire corrosion loose hardware Corroded guys and hardware risk catastrophic tower failure Dayton 2013

Guy Attachment (tower and anchor) Design and Construction Guy force must be properly distributed to the tower structure use the tower manufacturer’s recommended design Heavy duty professional grade forged, galvanized hardware Install turnbuckle safety wires Use articulated guy wire connections 10 degrees of free guy wire movement in any direction no chaffing or damage to guy wire or hardware from frequent tensioning, loosening or movement of the guy wire in the wind Use the manufacturer’s recommended guy attachments Dayton 2013

Guy Attachment (tower and anchor) Maintenance and Inspections Inspect guys at least once every three years Check all guy attachment hardware missing or loose turnbuckle safety wires loose, missing or corroded hardware guy wire chaffing or rubbing Integrity of tower structure in the vicinity of each guy attachment damaged tower structural components broken welds loose or missing hardware Replace all degraded or missing guy attachment hardware Dayton 2013

Lightning Protection Design and Construction Use at least three ground rods adjacent to your tower foundation at least 8 feet from each other and the tower base One ground rod for each guy anchor 8 foot galvanized ground rods (10 feet preferred) Large diameter (2/0) solid, tinned ground wire rugged durable connections to tower and guys buried connections to ground rods (Cadweld preferred) buried wire between ground rods a tower base Never use braided wire for tower grounding Dayton 2013

Lightning Protection Maintenance and Inspections Inspect all ground wire connections at least once every three years loose or missing hardware missing wires broken wires corrosion Repair all damaged or missing ground wires and connections Dayton 2013

Rotator Design and Construction Do not exceed the manufacturers load capacity use adequate size control cable consider the total length of the control cable rotator mounting hardware should be appropriate for your tower use galvanized steel or stainless steel hardware always use anti-galling compound on stainless steel hardware An under rated rotator will fail prematurely Dayton 2013

Rotator Maintenance and Inspections Inspect three months after installation Inspect every three years Check: excessive mechanical play in the wind corroded hardware An under rated rotator will be a major maintenance problem Dayton 2013

Antenna and Mast Design and Construction Appropriate antenna and mast for local wind and ice conditions heavy duty antenna when needed for local conditions Use only galvanized or stainless steel hardware use anti-galling compound on stainless steel hardware Use vibration dampening of antenna elements to avoid premature failure Well designed coaxial cable connections to the antenna electrical and mechanical Properly designed boom truss with professional quality hardware Select an appropriate antenna and mast for your local wind and ice conditions Dayton 2013

Antenna and Mast Maintenance and Inspections Inspect at least once every three years loose or missing antenna hardware loose or missing boom truss hardware corroded hardware ultra violet radiation damaged hardware coaxial cable electrical connection to the antenna coaxial cable physical connection to the antenna damaged structural components Coaxial cable connections to your antenna are easily damaged by wind, rain and UV Dayton 2013

Coaxial Cables and Control Cables Design and Construction Select appropriate cables for local ultraviolet conditions Use appropriate hardware for tower attachment consider local ultraviolet, wind and ice conditions #12 insulated solid copper wire is a good choice for fastening cable to a tower high quality electrical tape (Scotch 88) is also a good choice Electrically connect all coaxial cable shields to the tower at the top and bottom of your tower Fasten cables to your tower with high quality attachment hardware Dayton 2013

Coaxial Cables and Control Cables Maintenance and Inspections Inspect at least once every three years loose, missing or UV damaged cable attachments UV damaged cables Coaxial cables control cables and connectors damaged by water or moisture intrusion best inspected by using a time domain reflectometer, vector network analyzer, VSWR meter or other appropriate techniques good records are essential to detecting degraded coaxial cables Degraded coaxial cable seriously affects station competitiveness Dayton 2013

Summary Use this presentation to help you avoid the most common design and construction errors Inspections are essential to long term tower and antenna reliability Conduct major inspections during the first year after construction or major modifications every three years after serious storms or damage Regular inspections are essential to tower and antenna safety and long term reliability Dayton 2013