One aspect of this hobby that I enjoy is antenna design and experimentation. I’ve written before about my plan to build and off-center fed dipole (OCFD) which I may build in the future. However, I am currently looking at a different antenna design to replace my current G5RV when I finish cutting down trees on the property line.
When I was taking a class for my General upgrade, we were given an assignment to design an antenna for our QTH. I ended up dropping the class because of time constraints (like I did for CWA), but I was looking at installing a tuned doublet fed with open wire feedline. It’s a year later and I’m looking at replacing the G5RV that I’ve been using with this tried and true design – a tuned doublet or center fed Zepp.
While looking at purchasing ladder line, I came across TrueLadderline.com. They have what looks like high quality 600 ohm feedline, and pre-built antenna set-ups. Around this time I received my March 2020 issue of QST, where the cover story is “Build Your Own Open-Wire Line” which will inform my build.
For the build itself, I plan on using drip irrigation tubing cut to 4” sections for spacers. I will notch both ends and use cable ties to secure the wire. The cable tie will be fed through the tubing, will loop around the wire at each end and be pulled tight providing a secure fit. I will not use any splices or solder joints, and instead plan on using two continuous wires comprising each side of the feed line and antenna leg. The wires will be attached to a Balun Designs Model 1171 1:1 ATU Current Balun I already have on hand. This will allow me to connect the open wire feed line to my single-point ground system and feed through panel with a short length of coax to the tuner.
Here’s what I purchased:
- 1000’ 14 AWG XHHW 7 conductor wire @ $159.68 including tax & shipping
- 1000 8” UV resistant cable ties @ $29.20 incl. tax & shipping
- 100’ ¼” OD plastic irrigation tubing @ $6.04 (I also purchased supplies for our irrigation, so no tax or shipping included)
Total cost: $ 194.92 (more or less)
For comparison, TrueLadderline.com sells a 80-10m 125’ dipole with 150’ ladder line for $178 without tax or shipping. With what I’ve purchased, I can build a very similar antenna and have plenty of wire left over for other projects. Plus, The wire I’m using is larger gauge and sunlight resistant. The large wire should give me added strength and might help with Q factor. I think this is worth the extra $15 bucks. Plus, it’s a chance to experiment and try out the new NANOVNA.
For some good reading, the best source is the ARRL Antenna Book. Here’s some other articles I’ve found that inspired the project.
http://www.orarc.net/MultibandCenterfedZepp.pdf