RadCom April 2024, Vol. 100, No. 4

Review 52 April 2024 dog with two tails, happy at having a good antenna to play with. It was particularly nice to have resonant 10, 18 and 24MHz antennas, something I’d not had for a while. One afternoon, I heard a CW pileup on 12m with the DX signal at good strength. No callsign was being given, so I assumed it was a semi-rare station having some fun operating split. I placed my transmit about 1kHz up and tried a call. I got him first time, and it was TO8FH from Mayotte. Working T2C from Tuvulu on 20m CW a couple of days later was pretty straightforward too, and I was delighted. Many other excellent DX contacts followed on all bands from 40m to 10m, including stations such as 4W8X, ZL7A, VK9XY, VK9QO and TX7L. In some heavy weather, my bodge around the pole joint came back to haunt me, when the pole slipped and I could see slack on the wires. This did affect the VSWR although the antenna was still usable. I ordered some extra clamps to make the joint properly. Doing it properly meant there was no more slippage. Watching the antenna in winds we consider ‘modest’ on the coast or on high ground, but which would probably be thought of as ‘strong’ inland, I tend to drop it if a significant storm is coming through. The thinner sections of the pole flex considerably from about 2/3 up the pole and, whilst they will almost certainly take a fair bit of this treatment, it probably stresses the pole as well as the elements/ shock-cord sections. Of course, it’s easy enough to replace an element or shock cord if it breaks, but the pole is a bit more expensive. The antenna is so light to drop to the ground that it’s probably much better for your peace of mind to do that if a storm comes through. My rule-of-thumb is that if a storm is going to be over 40 knots or so, I drop the antenna rather than watch it whipping around. The Signature 9 will handle 400W quite happily and, looking at the construction, I’m sure the increased limit for Full licence holders of 1kW would be fine on CW or SSB. If you’re running data modes, you’ll want to throttle things back, thinking of your PA stages, but it should cope with 500W continuous without too many problems. On 10 and 12m, Callum suggests creating a loop at the end of the elements to avoid corona discharge. Final impressions I wrote this review over a period of several months to get a feel of how the antenna worked in different conditions. I can only say that I have been delighted with the performance across the bands. The only band where I felt it wasn’t quite so good was 15m; on this band it didn’t seem quite as lively as on the other bands. I discussed this with Callum. He uses a quarter wave on 15m on some of the other DX Commander vertical antennas in the range, rather than the loaded three- quarter wave that’s used on the Signature 9. Running the numbers through the computer, there didn’t seem to be very much difference between the two configurations. Don’t get me wrong, the antenna works fine on 15m, but I felt it lacked the ‘sparkle’ I saw on the other bands. On all the other bands though, I felt performance was excellent and surpassed my expectations. Construction of the antenna is actually very simple so, even if you’re like me and find flat-pack and instructions hard to follow, don’t worry. Callum includes the following section in the User Guide which sums it up nicely: “Please remember that all we are doing is creating resonant lengths of copper wire, held rigid on a telescopic pole using shock-cord. In the main, our element lengths will be a quarter of a wavelength long (sometimes we can use a loaded element up three quarters, giving us near 5/8 performance). We can make this as difficult or as easy as we like but if you miss a bit of the User Guide, or don’t understand something, remember this is just supposed to work. And it will. The laws of physics won’t change between Warwickshire and your place.” I’ve no hesitation in recommending the DX Commander Signature 9 vertical antenna kit to you. It’s priced at £399, and can be obtained from [3] . References [1] https://www.youtube.com/channel/ UC6wLPPAzu7iPDMaUeHoVvJw [2] https://dxcommander.com/guides/ [3] https://dxcommander.com/product-category/ products/antenna-kits/ FIGURE 3: The working antenna.