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2024.01 I decided to build a doublet antenna at my QTH. I wanted to homebrew the ladder line, homebrew the 4:1 balun, make the radiating wires out of cheap speaker wire, and have it cut for use on 80m. I scribbled a plan on a piece of paper on 20 January 2024:

In the meantime, I was reading about the rest of the pieces of the project. I saw that I needed a 4:1 balun and used the excellent guide from M0PZT with a couple 240-43 toroids I had laying around (as I understand it, this isn't the best mix choice but it worked fine for me). The next day, it took no time to wind two toroids:

Two days later on 23 January 2024, I began the construction of the ladder line. I bought some long pieces of PVC pipe and cut the pieces down to about 4 inches. I did not design the spacers to give a "perfect" impedance -- perhaps I would have had better SWR if I did, but that's not the kind of ham I am :). I unrolled speaker wire and used a long zip tie to attach the pieces of PVC pipe to the two separated pieces of the speaker wire. Rinse and repeat:

Another two days later on 25 January 2024, I was able cut down all the PVC pipe I had bought into 4 inch pieces. So I began attaching them to the speaker wire. Here's a picture partway through that process:

I used all the PVC It gave me a nice long piece of ladder line, which I show extended down my hallway (with a bonus kitty)

The same day I wired up the two halves of the balun. It looked like this:

The next day I was able to actually put everything up in the air according to the original plan. Here's a shot from where the ladder line goes to a window up to the dipole (which itself is difficult to see):

All that was left was to bring the wires of the ladder line insdie (my windows are aluminium so it will be better to NOT bring them across that metal, but that's a problem for the future) and get it to some coax so I can work with it. So I set things up in a very ham radio style:

With this it was ready to test. I first got out my VNA and took some SWR measurements on 80m, 40m, 30m, 20m, 17m, 12m, and 10m. The screenshots are included now:

I was very pleased with those results, although 80m and 40m were a bit high. So it was finally time to test the antenna with a radio. I decided to try to work TX5S on 12m at their DXpedition to Clipperton Island. After about 3-5 calls, I made it through and got the qso! Great antenna; good fun!

first posted 2024.02.15