Transcript NN4ZZ Tilt Plate Project June 2007 -- V7

NN4ZZ
Tilt Plate
Project
June 2007 -- V7
Goals
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Free standing, tilt-over tower
Gain antenna for 20-10M
Antenna height 70-80 feet
Convenient operation
Antenna maintenance from
the ground, “no ladders or climbing”
Tower and Antenna
selection
• U.S. Towers MA-850
• Steppir 4 el yagi
• The next few slides show the tower
construction and steppir specs
U S Tower MA 850
MA-850 foundation
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7 x 7 x 7 -- 13.5 yrds
4,000 psi fiberglass
Tiltover base
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Motorized
winches
Steppir 4 element
• Monobander on 20-10
• Control from the shack
• Tracks transceiver
Steppir Specifications
Problem / Solution / Strategy
• Problem - How to lower an antenna with a 32
foot boom and 36 ft elements to ground level.
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• Solution - Develop a method to tilt the antenna
so it can be lowered to ground level for all
maintenance
• Strategy - Keep it simple, make it sturdy
• Over engineer the design. If its worth doing, its
worth over-doing
Tiltplate 1 & 2 - Two versions
• The first design (tiltplate1) has been in
service since April 2004.
• I decided to build another one for my
second tower. A new design (tiltplate2)
was created with direct rotator
mounting.
• The power point is divided into
sections to highlight both designs
• Both versions work equally well
Tiltplate 1 & 2 - Common
Components
• Steppir 4 element 20-10 meter yagi,
• U S Tower MA 850, 85 foot tubular crankup
tower with motorized winches.
• Same bearings, shaft, etc used for both
designs.
• Aluminum plate material is the same, just cut
differently
Tiltplate 1
Mast mounted plate design.
Major Components
• Yaesu G-2800 DXA rotor
• Aluminum plates hinged on an
aluminum shaft. Use of pillow bearings
to provide tilting capability
G-2800 DXA
Tiltplate diagram
Design Notes
• Uses gravity to hold boom plate in place. Boom
plate is held about 5 degrees off vertical. The
boom is rotated to compensate for the offset and
to keep antenna elements parallel to the ground
• No latch - allows boom plate to tilt in high wind
• Supports a dynamic loads of 3,000 pounds on
bearings, shaft.
• Boom plate is kept close to the rotor to minimize
offset load
Tiltplate Materials
• Stainless steel clamps, McMaster Carr
part #29535T11 (for 1” diam shaft) pg
1446
• ½ inch aluminum plate 18 x 12, McMaster
Carr #89155 k29
• Severe duty pillow block bearings,
McMaster Carr #6494K14
• 1 inch diameter aluminum shaft, McMaster
Carr #5911k36
Aluminum Shaft
Bearings
U bolts for shaft
Tiltplate
Building the Steppir
Fully Assembled
(Tower tilts to the left and toward viewer. Elements are parallel to the tower)
Closeup of Tiltplate
Tiltplate 2
Rotator “direct mounting” design.
Major Components
• Same basic concept. Same materials
used for construction.
• Also using a Yaesu G-2800 DXA rotor
• Mast plate directly mounted to the rotor
instead of using a mast
• Fewer parts (no mast or mast clamps)
G-2800 DXA
TiltPlate 2
Mast for boom truss
1" shaft
U Bolts
Bearing
Bearing
12 inches
12 inches
Boom Plate
½ inch
Mast Plate
½ inch
boom
24 inches
18 inches
2 ½ inch Boom. Note:
boom plate slightly out at
bottom, top clearance
less
6 inches
TiltPlate 2
Tiltplate 2
• Direct mount to
rotator
• Eliminates the
possibility of mast
slippage
• Same basic tiltplate
design
• Fewer parts (no mast
or mast clamps)
• Cleaner look
Tiltplate 2 installed
Tiltplate 2 - view from below
Tiltplate 2 – tower at 70 degrees
The Wind
• Most frequent question is “does it bang around
in the wind”? Answer: No does not move at all
expect in high winds over 30 MPH
• Wind from the ends has no effect
• Wind from the boom plate adds to down force
• Wind from mast plate is mostly blocked
• Designed to gently lift in very heavy wind
Tiltplate performance
• No surprises
• Highest wind gust so far, 52 MPH on
July 4, 2004
• Smooth tilting operation, no problems
in over 3 years of operation
• Costs about $400, most expensive item
is the aluminum plate.
Completed
project
For More Information
• Web page: www.nn4zz.com
• Email: [email protected]
• Opening slide, “the wave”
Page, AZ
• Dish Antennas, the Very Large
Array in Socorro, NM