Finished Tower Base

Now that we have backfilled the base and guy anchors for our tower, we are ready to have the equalizer plates and guy wires attached. We are planning to use two sets of star guys on the tower – one set of 6 guys at 50’ and a second set at 95’ (5′ down from the top). Star guys use special brackets where the guys attach to the tower to connect two guy wires on each tower leg for a total of 6 at each level instead of the usual three. This prevents the tower from torque-ing when the rotators start and stop moving the large beams (we are using a pair of SteppIR DB36’s – full-size 40m beams weighing about 165 lbs. each).

We also ordered a number of parts for the final tower over the last couple of days. Here is a rundown of the components and some links in case you are interested in what these components are:

• Two SteppIR DB36 Beam Antennas
  
• A DX Engineering  Antenna Phasing System
  
• An M2 OR28000 Rotator (for the top Beam)
• A K0XG Rotating Ring (to rotate the lower beam around the tower)
• Two Green Heron Rotator Controllers
• A DX Engineering 8-port Remote Antenna Switch
• Star Guy Anchor Brackets
• Phillystran Guy Wire Material
• Two additional 10’ sections of Rohn 55G tower (to extend the current tower kit to 100’)
• A 21’ x 3” Galvanized H.D. Mast

The SteppIR antennas cover all bands 40m – 6m including the WARC bands. One of the DB36’s (the top one) will have an 80m dipole option that uses a wire running parallel to the beam (36’) plus the end elements of the antenna and a pair of loading coils to create a rotatable 80m dipole. This should be reasonably effective at the 105’ level where this antenna will be mounted. The ring rotator allows the lower beam to rotate around the tower and the Green Heron Controllers synchronize the upper Beam’s rotator with the lower ring to move both antennas in the array together. The Green Heron controllers also come with software that allows them to be operated over the internet which will allow me to use the station and move the beams while I am traveling via a PC and the Internet. The DX Engineering Broadband Matching system allows the two Beams to operate as an array increasing the overall gain of the system and improving the radiation patterns of the antennas. The Matching System and the two associated antennas can be used three ways – as an array in-phase, as an array out-of-phase and individually. This allows us to cover a much larger set of takeoff angles to optimize the performance of the system based upon the propagation conditions at any given time.

We chose Phillystran Guy material which is made of Kevlar and is non-conducting. This ensures that the guy wires will not be resonant on the HAM bands and upset the tune or interact with the antennas on the tower. The Phillystran will transition to a normal steel guy wire near the ground for safety reasons. Rohn 55G tower is strong stuff and we chose it to maximize the antenna and wind loading capacity of the system. Check out the 55G Brochure via this link for details on the 55G tower kit and related hardware. Finally, the 21’ H.D. mast will allow us to add additional antennas for 2M and 70 cm above the top SteppIR beam in the future. The first 5’ of the mast goes inside the tower which leaves 16’ of the mast to mount antennas on. This allows us to put an antenna as high as 115’. The mast is also climbable which should make for some exciting times (and pictures) sometime in the future.

We are also planning to add an 80m Delta Loop antenna and a 160m Inverted-L antenna to the tower. These antennas will be selectable at the tower via a DX Engineering Remote Antenna switch. The tower is located right next to our current SteppIR vertical antenna which has a large radial field under it (forty-eight 85′ radials). We need to move the Vertical antenna to a new location due to the tower but we can re-use the existing radial field to improve the performance of the 160m and 80m antennas on the tower. We plan to add a few 170′ radials to the field to improve its performance on 160m.

We are in the process of completing an HFTA and EZNEC modeling analysis of the complete antenna system to finalize the height of the two beams and the design of the 160m and 80m antennas. Look for a future post on this work. Right now it looks like the two beams will likely perform best when installed at 102′ and 65′.

You can read more about our tower project via the articles which follow:

• First Tower Part 1 – Ground Broken For New Tower!
• First Tower Part 3 – More Excavation For Feedline Conduits
• First Tower Part 4 – Tower/Antenna System Analysis And Design (Planning And EZNEC)
• First Tower Part 5 – Tower/Antenna System Analysis And Design (HFTA Analysis)
• First Tower Part 6 – We Have A Tower!
• First Tower Part 7 – 100 ft Tower Completed!
• First Tower Part 8 – VHF/UHF Antenna System Design
• First Tower Part 9 – Feedline Conduits And Electrical Power Complete
• First Tower Part 10 – Building Yagis (70 cm)
• First Tower Part 11 – Building Yagis (2m)
• First Tower Part 12 – Building Yagis (SteppIR DB36)
• First Tower Part 13 – Building Yagis (SteppIR DB36 Continued)
• First Tower Part 14 – Building Yagis (SteppIR DB36 Continued II)
• First Tower Part 15 – Building Yagis (SteppIR DB36 Completed)
• First Tower Part 16 – Building Yagis (Second SteppIR DB36 Completed)
• First Tower Part 17 – Feedline Breakout System
• First Tower Part 18 – Antennas On The Tower (Preparation and Upper Yagis)
• First Tower Part 19 – Antennas On The Tower (System Integration)
• First Tower Part 20 – Antennas On The Tower (System Complete)
• First Tower Part 21 – Antennas On The Tower (Final Odds and Ends)
• Complete Presentation on Amateur Radio Station Design And Construction

– Fred, AB1OC