Caius' Lab - Antennas

Setting up the DX Commander Expedition Antenna

2025-04-21T00:00:00+00:00

Recently I got a new DXCommander Expedition Antenna</a> for Parks on the Air (POTA) use. After some experimentations, this week I decided to finish the tuning, and make a few contacts with it</p>

Initial thoughts #</span></a> </h2>
It's a large antenna! See in context with a large pine tree.</p>
It took a while to set up, with a couple of saw horses it's not too bad. Having the antenna at a reasonble height avoids all be bending over to cut and measure things. Once it was clear where everything went, and had the clamps trimmed to size, the assembly went smooth.</p>
I also tried tryting to extend the antenna while it's vertical. I don't recomment this approach. It doesn't work and it will come crashing down and "colapse" quite fast.</p>
The best option for deploying in the field is to lay it down, assemble everything, then walk it up. It's light enough that it's easy to do with a single person.</p>
The good #</span></a> </h2>
The tuning! 40 and 20 meters are spot on, with barely any noticeable movement of the SWR meter while transmitting.</p>
20 meters is well below 2.0 SWR across the entire band. </p>
For 40 meters, the story is the same. </p>
The 40 meters element ended up a lot longer than I expected. So long, in fact, that I don't need any shockcord at the top. It reaches the top of the pole, and I use the little clear platic tubing to hold the element in place. A loop of shockcork keeps me from loosing the little plastic tube.</p>
I opted for a "perfect" 40 meter tune, and this probably lead to the long element, and the not so great 15 meter performance (more on that later).</p>
The OK #</span></a> </h2>
Tuning the 10 meter band was a bit more finicky than I liked. I was able to get it under 3.0 across the whole band, and I was able to use it fine without using the internal ATU of the radio.</p>
(Sorry, no image of the 10 meter turning. I closed the software and didn't save the image, and I only realized this after the antenna was down. I'm not going to stand it back up, in the rain, for one image. You'll have to trust me on this one)</p>
The meh #</span></a> </h2>
15 meters. It's tuning is not great, see below.</p>
In practice, I get under 2.0 with the Icom 7300 (very brief testing). It's usable without an ATU, and well within ATU limits if I'm using a radio that has one built in.</p>
It's possible the "overtunning" the 40 meter band got me worse performance here. But it's a compromise I made on purpose. I use 40 meters a lot more often than 15, and I'm happy with the overall result.</p>
Also, the elements are a bit loose than I'd like. The tensioning loops ended up very close to the spreader plates. This might be my error in assembly, but for future reference, having the loops a few inches down is OK, as there's pleny of shockcord to accomodate this.</p>
Conclusions