How to Build a Dipole/Inverted-V Combo Antenna
Editor’s Note: Over the next several months, OnAllBands will be featuring a series of articles from Harry “Trippy” Brown, AC8S, longtime amateur operator and antenna builder/tester who’s never let his visual impairment stop him from enjoying the hobby he loves. As the title of this series states, we hope these articles provide you with invaluable insights as you pursue your own successful antenna projects.
In last week’s post, you learned the items you’ll need to make your own dipole/inverted-V combo antenna and how to determine the necessary length of wire. Today, I’ll be taking you step-by-step on how to build the antenna. To read the first 12 entries in this series, just enter “Trippy” in the OnAllBands search box above.
Putting Up the Balun or Unun
Outside
- If putting a balun or unun up on a hook on a balcony for a dipole/inverted-V combo or end-fed antenna, you’ll need a foot of rope so you can pull it through the hook and tie it in a knot to ensure that it won’t come off. Or you can use a foot of copper wire, pull it through the hook, and wrap it around.
- You can also hang the balun or unun in any other appropriate outside location that suits your needs.
Inside
- You can hang the balun or unun on a blind rod; however, don’t hang one on a curtain rod because it’s too flimsy to support the weight of the balun/unun, wire and coax.
- You can also hang the balun/unun on a nail, but make sure the nail sticks out no less than 5 inches from the wall. You’ll need 5 inches of rope or copper wire to securely fasten it at the center feed point so it won’t come down.
- If using a blind rod, you’ll need 10 inches of copper wire or rope to
support the weight of the balun/unun, coax, and the rest of the antenna.
How to Hang the Balun or Unun
- Measure the appropriate length for the rope or copper wire (5 inches for a nail or 10 inches for the blind rod). If you’re blind, put the piece of rope or copper wire at the beginning of your braille yard stick.
- Go to the right until you get to the 5-inch or 10-inch mark. If you’re blind, 5 inches is the letter “e,” with a long plastic line behind it; 10 inches is the letters “a” and “j,” right next to each other, with a long plastic line behind it.
- Cut the copper wire or rope to the desired length.
- Put the rope through the center hook on the balun/unun until the rope is even with the hook. If you’re using copper wire, put it through the hook at the center of the balun/unun until one end of the wire is even with the hook.
- Pull the rope or wire through until your thumbs meet at the center hook, and each end of the rope/wire is about where your left and right wrist are.
- Pull both ends of the rope so the balun/unun is hanging on the nail or on the blind rod, and you have both ends of the rope in your hand. Or if using copper wire, pull the balun/unun so it’s hanging on the blind rod and you have both ends of the copper wire in your hand.
- If using rope, make a knot so the balun/unun will not come down. If using copper wire, fold it over as many times as you can to secure it in place.
Trimming the Wire Down to the Exact Length for Each Leg
For this example, I’m going to make a halfwave dipole/inverted-V combo for 80 meters because I know it will tune on 80, 40, 20, and 10 meters.
- Cut 3 inches from the first coil of the two 66-foot coils of copper wire in order to get the leg down to 65 feet, 9 inches. (See Part 12 on measuring leg lengths). Take the wire and lay it on the yard stick so its tip is right where the yard stick begins.
- Using your left hand, hold the wire with a finger or thumb so the wire cannot move.
- Measure 3 inches. Slide the copper wire 3 inches to the right. If you’re blind, slide the copper wire to the right until it says 3; it’s the letter “c” with no number sign, and behind the “c” there is a long raised plastic line.
- Pick up the wire between your thumb and finger, holding your finger at 3 inches. Use wire cutters to trim the wire so you have your first 65-foot, 9 inch leg for the antenna.
- Repeat this process for the second leg.
Measuring the Halfway Point of Each Leg
- After you have hung the balun, measure how far it is from the hook where each leg connects to the balun to the end of each leg—as far as you can string them out.
- Measure from the left hook of the balun all the way down to the place that the left leg is going to end. Put a marker (e.g., a tie wrap or piece of tape) at the halfway point between the balun and the end of the leg.
- Repeat for the right leg, measuring from the right hook on the balun. For this example, my balcony has 14 feet for each leg, so I’ll measure to get 7 feet, the halfway point between the balun and the end of each leg. As I’ve discussed before, I don’t have 65 feet, 9 inches to stretch each leg, but coiling will take care of that problem.
Connecting the Legs
- Remove the pieces of tape off of the first 66-foot coil, which will be the left leg. If you can see, you’ll be able to simply undo it. If you’re blind, however, you’ll have to feel the tape, find where it begins, and pull it off. There are usually two pieces of tape on these coils of wire.
- Take the coil of wire to where the marker is at the halfway point. Have a partner hold the coil where the marker is and connect the left leg of the antenna to the balun.
- You’ll want the wire to go through the left hook on the left side of the balun 1 ¾ inches. So put the wire through the I-hook until it is even with the I-hook and then push it through until it’s 1 ¾ inches up from the I-hook, which would be where your thumb and your hand meet.
- Hold the wire (don’t let it move) and bend it until it touches itself, then bend it a little more so it cannot come off the balun in high winds. Note: My installations have stayed up in 50 mile per hour winds.
- While holding on to the coil at the halfway point (but loose enough so the end of the wire that’s not connected to the balun can be gently pulled to the place where you cannot string any more wire), let your partner pull the wire to the left until it gets to that end place where you can connect the end insulator.
- There are four holes on the porcelain insulator, two on each end, with
each of the two holes across from each other. Put the end of the leg through the two holes on the porcelain insulator, one hole on one side, then go across through the other hole. After you get the tip of the leg through the second hole, the tip of the leg should be touching your thumb. With your left thumb on the left hole and your right thumb on the right hole, move the insulator to the left until there is enough wire to go from the right hole along your right thumb until your right thumb meets your hand; now you have enough wire. - Keep the insulator in place with your left thumb and finger. Take that wire on the right side of the right hole of the insulator and bend that wire to the left so it will touch the wire that is to the left of the insulator.
- Bend that little piece of wire to the right of the wire it is touching. Keep bending until you cannot bend it anymore.
- Move that insulator to check if it stays in place. If not, repeat previous steps to make sure it’s secure.
- Repeat steps above to connect the right leg.
Do you need to tie off the ends?
If you are building a dipole/inverted-V combo, you’ll need supports on each end. Just let each leg hang straight down at a 90-degree angle and tie it off. I had to tie off my dipole/inverted-V combo at each end because of the balcony; I didn’t want the copper wire legs touching anything.
For information on coiling your dipole/inverted-V combo antenna, see Part 11 of this series.
Final Thoughts
Hopefully because of this series of articles, you have now built and hung your end-fed or dipole/inverted-V combo antenna, or perhaps used a tower as a vertical antenna, or contacted me and received an article about the snake antenna (maybe you’re using one right now).
You’ve also read about how any ham can get on HF using whatever length of dipole/inverted-V combo or end-fed they want because of coiling. Now nobody has to leave the hobby because of antenna restrictions! As I’ve asked before, I’m curious if coiling works for portable operations. It’s great for fixed operations, but if you want to try it for portable ops, please do and let me know how it worked and what kind of signal reports you received. I think you’ll love it portable!
Happy hamming, and I’ll see you somewhere on HF!
73,
Trippy Brown, AC8S
Questions? Comments? Reach me at hebrown3rd@gmail.com.
