Shortened Vertical Tuning
Tuning the antenna can be a bit tricky but it can be done. Having a NanoVNA antenna analyzer helps a lot. The first thing to do is make sure the two radials are cut to 16 1/2 feet long. Next start with 20 meters by completely shorting out the loading coil. Typically a quarter wave vertical for 20 meters is approximately 16 1/2 feet. I started out with 17 feet knowing that this was too long. Its easier to shorten an antenna that is too long than to add length. Since the fishing pole that is used for supporting the antenna is 20 feet long, I added 3 1/2 feet of left over chalk line to the top of the vertical wire. This way when the 20 meter length is at its final length, I can adjust the overall length of the antenna so that the balun sits on the ground.
Next tune the antenna to 30 meters. Start by putting the shorting clip to the screw that is in between the two coils. Check for resonance. if its low by a lot, take off a turn and re-check. If its low by a little bit, just separate 1 or 2 turns of the un-shorted portion of the coil. Doing so reduces the coils inductance by less that removing a turn.
Once satisfied with 30 meters, go back and check 20 meters. When everything was good on 30 meters I took some hot-melt glue and applied it perpendicular to the direction of the coils to keep them in place.
Finally for 40 meters, move the shorting clip to the top screw, which uses the entire loading coil. Repeat the tuning process as before. When finished, apply hot-melt glue to the 40 meter turns to secure them in place.
The first time I used this antenna was when I activated the Clearfork Gorge Nature Preserve, K-9398 using my QCX-mini transceivers. Below is a photo of the vertical antenna set up at the gorge during the activation.
Its kind of hard to see the antenna. I use yellow paracord for the guy lines which helps to see where the antenna is.
The results? I am pleased with this antenna. In spite of its compromises it works well – even running QRP. My first activation with it I made 15 QSO’s on 40 and 20 meters. I typically get 569 reports while running 5 watts.
Thanks for the inspiration. I’m new at this and EFHW has been my go-to antenna for the past couple years. A couple days ago I decided to give vertical another try, so I built a version of this using leftover #18 wire from Lowe’s. The coil is #20 solid, insulated electric pet fence wire wrapped around a scrap plastic tube that was originally a shipping package for a different antenna. With it hung from a 20ft telescopic flag pole, and after two tries making some tuning adjustments, contacted Austria on 20m from Virginia.
-Gary (K4GRK)
Wow! That’s great Gary! Glad it worked so well for you.
— Mike