First Tower Part 3 – More Excavation For Feedline Conduits

We are planning a pretty extensive feedline and control system for our new tower. The plan currently includes:

• Two 7/8′ hard lines to feed the SteppIR DB36 array
• One 1/2″ hardline to feed 80m Delta Loop and 160 Invert-L antennas on the tower
• Two 1 5/8″ hard lines to feed future UHF antennas
• A total of 6 control cables for the two SteppIR Beams, two rotators for the Beams, Stack Antenna Phasing System and Remote Antenna Switch
• Capacity for 6 additional control cables for future use

We also need a 120 VAC outdoor outlet at the base of the tower to provide power for the ring rotator.

The accommodate all of this, we are placing several plastic conduit pipes in a trench from our shack entry point to the tower. The conduits include:

• One 4″ run for the three new hardline feeders
• One 6″ run for the future UHF hard lines
• Two 2″ runs for control cables
• One 3″ run extending beyond the tower to the back of our lot for possible future use with additional antennas in this location
• One 1 1/2″ conduit for the 120 VAC cable to the tower

As you can imagine, this requires quite a trench! This part of the construction is compounded by the existence of a sprinkler system and train pipes for the rain spouting as well as the radial field all of which are already in place in the area where the conduits must run. This is yet another job for Brian Veillette (Nashyei@aol.com), our excavation contractor on the project. As you can see from the pictures below, Brain has done a very careful job of creating the trench to minimize the damage to our lawn.

The conduits are laid in a bed of sand and then covered completely with another layer of sand to ensure that the pipes are not damaged by freezing and thawing of the ground. We also constructed two moisture drains under the conduits at the ends and place small holes in the pipes at the bottom to allow the water that will ultimately accumulate in the pipes to drain into the ground. Also, note the drainage pipes installed on the rain spoutings to carry rainwater from the room away from the conduit area and the shack in the basement. These are important steps to ensure that the feedline in the conduits stay dry and perform well for an extended period of time. It’s also important to create a gradual upslope at the ends of the conduits which will contain hardline feeders as these cables are stiff and cannot be bent sharply as the come out of the ground. This is accomplished by using a pair of 22.5-degree elbows on each end of the conduits to bring them out of the ground.

As you can see, we still have some work to do to complete the conduit work. We expect to finish this part of the project early next week. Once this is done and the remaining parts arrive for the tower, we will be ready to put it up!

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 2 – Tower/Antenna System Design Details And Equipment Ordering
• 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