Antenna Tech

Choosing a Ham Radio HF Antenna—DX Commander Signature 18 Nebula Part 2, Installation Day

Troy, AC80W, chronicled his installation of the DX Commander Signature 18 Nebula eXtreme HF Multiband Vertical Antenna. Find part 1 of this series here: “Making the Selection and Prepping for Installation

So, the date had been set, the supplies assembled and, most importantly, the installation team recruited. It was now time to get the DX Commander Signature 18 Nebula in the air. If all went according to plan, I would be on the air by the end of the day.

I had done my best to have everything laid out in the order it would be needed. I had the element wires cut exactly to the prescribed length in the owner’s manual. I even had the radials cut and the fork terminals installed. The whole idea was to have as much of the preparatory work done as possible before the team arrived.

The one preparatory item I would change is concerning the manual. I emailed the Nebula instruction manual to everyone a few weeks before the install. I try to work paperless as much as possible. The manual is very well laid out, but due to the way it is arranged, having a paper copy with highlights and notations for this particular antenna would have been much easier than trying to operate using phones.

Immediately after breakfast, the team launched the attack. One team started working on burying the coax. We ran DX Engineering 400MAX Low-Loss 50-Ohm Coaxial Cable from the antenna to a DX Engineering Utility Enclosure mounted on the side of the house next to the weatherhead. DX Engineering RG-213/U 50-Ohm Coaxial Cable was used to go from the enclosure through the weatherhead into the shack.

DX Engineering PL-259 Connectors were attached using the DX Engineering Cable Prep Tool Kit and the DX Engineering Ultra-Grip 2 Crimp Connector Tool Kit. This crew probably produced the most sweat but, in the end, you could not even tell they cut a trench through the yard.

men readying a plot of land to erect an antenna
They bury team closing the trench after the coax cable was buried. (Image/AC80W)
men preparing gear in a small storehouse
A small team assembles connectors and grounding elements (Image/AC80W)
men prepping antenna components
No matter what we were working on, there was always time to share some knowledge. (Image/AC80W)

I should note a few things about our coax bury project. I had all buried wires and pipes marked for the safety of the crew and our house. They used a gas-powered edger to cut a shallow trench which made it easier, but they still had quite a time getting the coax in the trench. The composition of our soil was too rocky for an electric edger, so they had to resort to a commercial gas unit.

Another crew started getting the guy anchors in the ground. I chose DX Engineering 15-Inch Rope Guying Earth Anchors. These are extremely heavy duty and should last a lifetime. The position for each anchor was spotted according to the manual, and each one was screwed into the ground by hand. This crew then set and stapled the radials after the anchors were put in place.

The third crew assembled and erected the antenna. A series of three sawhorses were set up to support the mast while it was being assembled. They extended the mast and pulled each joint until it was tight. Each joint was taped with a DX Engineering Coaxial Connection Weatherproofing Kit and the clamps were installed according to the manual.

men assembling an antenna mast outside
Many team members prefer to use their own tools for familiarity but always have everything necessary available for them (Image/AC80W)
men assembling an antenna mast on sawhorses
The antenna erection team made sure they had ample support to make the work easier. (Image/AC80W)

It was then time to install the rings and elements. The ground ring and driven ring were put into place first and secured. The remaining four spacer rings were then put in place. The preassembled radiating elements were attached to the driven ring. Please note, it does matter what order they are arranged to avoid harmonics. The radiating elements were secured and tensioned with the shock cord per the manual.

Finally, the guy ropes were attached to the spacer rings, and we were ready to raise the mast. The guy ropes were fed through the anchor eyelets, and tension was maintained in all three directions as it was raised. We used a level to make sure it was plumb, and all ropes were tied off accordingly. I used Mastrant-P Guy Line Rope for this project.

men running coaxial cable off a spool
Every phase of this project was a multi-person operation. Many hands make for light work. (Image/AC80W)
men assembling radial wires for an antenna
This was a great opportunity to teach young and old alike new skills in our hobby. (Image/AC80W)
men erecting a vertical antenna mast
A level was applied to all four sides to ensure the mast was plumb. (Image/AC80W)
men putting a vertical antenna mast up in the air
It’s beginning to look like an antenna! (Image/AC80W)
vertical antenna mast erected in a grass lot
The DX Commander Signature Nebula eXtreme HF Multiband Vertical Antenna covers 80-6M and is rated at 1,500W SSB/CW, 400W FT8 and other digital modes. (Image/AC80W)

Finally, the radials were attached to the radial ring. We used Jet-Lube SS-30 Pure Copper Anti-Seize on each bolt and nut. This is messy stuff but adds huge value to the finished product. Lastly, we attached the center conductor wire from the coaxial connector to the driven plate, and it was done.

Using a Rig Expert Stick Pro Antenna Analyzer, SWRs were checked and all were below 1.3:1. It really does pay to cut these elements exactly as prescribed. The coax was secured in the shack and ran to the transceiver.

Getting on the Air with the Nebula

This is the first truly resonant antenna I have ever owned. The benefits of such resonance have become very evident to me. The next morning, I turned on my Yaesu FTDX-101MP and the first station I came across was from Australia (VK). I was able to make contact, sealing the deal on how happy I was with its performance. Furthermore, I used the DX Commander Nebula in the Ohio QSO Party and had my best score ever.

I could brag on this antenna until the cows come home, but there is a much more important thing that happened that weekend. Members of three clubs from three different counties came together and got the job done. I am forever grateful for their help and support.

I owe a HUGE debt of gratitude to the members of the Lorain County Amateur Radio Association, the Seneca Radio Club, and Huron County ARES for their blood, sweat and tears.

Until next time, 73

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