1. 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

2. A Typical Tower and Antenna

3. Your Tower in its Environment
Dayton 2013

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

15. 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

16. 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

17. 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

18. 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

19. 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

20. 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

21. 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

22. 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