Antenna Build Series 3 - Trapped Dipole

[@ryane.7894]

Thanks for the videos! I appreciate that they are step by step without a lot of fluff. I’d love to see a full wave loop!

[@kj7iaz]

Haha. Me too. I might do a 40. I can for sure do 20. Planning a vertical video then I could do a full loop when it warms up a bit.

[@RS_AFKing]

Great Video Bud! First 1K video. What an amazing achievement. Keep it up 👍

[@kj7iaz]

Thanks a ton!

[@videokfm]

thanks. will be saving this video. regards ZS1MMB

[@kj7iaz]

Thanks!

[@ronandrew878]

Great video, good to watch this stuff, shame about the annoying music though . Thanks

[@kj7iaz]

Thanks ! Do you think no music, lower volume, or different song, would be better? I'm always trying to improve, I'm an amateur radio operator and an even more amateur director. Lol. I appreciate the feedback, let me know your thoughts.

[@i8BBQ4Lunch]

Thank you for a great video.

[@kj7iaz]

Thanks for the comment and sub.

[@thomasobert5261]

Very nice, thank you. I want to do an antenna like this. Do you know why the turns are cross connected? Is it simply to get 2x turns from one length (ie 7 turns becomes 14) or is it something more?

[@kj7iaz]

I'm not exactly the expert on the subject,, but it helps create the needed capacitance.. otherwise it would just be a loading coil. The traps could be made from a torroid inductor and capacitor too, and much smaller, I want to do a future video on that as this got kinda long already. If you have some spare coax laying around, this is a great use of it, plus a very inexpensive way to get a good antenna up.

[@thomasobert5261]

Ahh yes, the C. Now I get it. The coax has pF/m so a given length has a specific L and C. Thanks.

[@kj7iaz]

I also like the fan dipole if you have the space for lowest band you use. And use longer spacers all the way down. This design is good for shortening the overall length, it really depends on each individual person's availability of space, supports, rules, etc.

[@richard-fy2mu]

I am HOA restricted mast 20 ft. Now can slope so conceivably trapped as an inverted vee leaning or sloped. Setting 20 trap at 14.0 how narrow will the 40-band width be? Is it going to be either CW/DIG or Phone? My current set up excludes any 40 and places 20 ends too low to ground.

[@kj7iaz]

It'll be pretty narrow, you might do a flatter lower inverted v for just 40, it'd be nvis, but most likely still usable with great success.

[@carypeaden4147]

I am a new ham (so still learning). I was surprised you used coax wire rather than single conductor wire for the trap. Would a single conductor wire also work? If so, what advantage did the coax provide?

[@kj7iaz]

I used coax as per the instructions I used. A trap is a tuned circuit with inductor and capacitor. So I think with coax it's giving it more of both. Sorry I can't be more exact haha

[@ccdanieldb]

Hello, Thank you for the video. I would like to build a 6, 10, 12, and 15m trapped dipole and think I have the trap part down, but I would like to know how I calculate the (electrically shorter) parts of each segment. Is there a formula I missed, or is it just trial and error. Thanks again for the video.

[@kj7iaz]

In the video, I mention the website I used. In the calculations there is an effective length of the trap, just subtract that from the length you would cut for a dipole. As you move out, it adds up. So you'll have to keep track. It'll be close and fine tune by slowly trimming. Hope that helps. Feel free to email me if need be, I can maybe explain better.

[@ccdanieldb]

Ok I got it, the webpage tool you pointed to suggests the effective length. "The Effective Length is the estimated amount that the next-lower-frequency leg of the trap antenna must be shortened to obtain resonance"

[@ccdanieldb]

@@kj7iaz Am I wrong? After putting this down in a spread sheet it looks like I may not be able to use the 12m and 15m bands after the 10m band. The length of wire needed gets negative when the bands are too close together.

[@kj7iaz]

10 and 12 are delicate. 10 and 15 should be ok. You can play around with the diameter and length of trap. Find get a combination that has less effective length. Also. This is only one way to build a trap. Could try a different version. Or experiment on your own, a trap is simply an inductor and capacitor in parallel. You could also do a fan dipole, it might work better for the bands you are trying to use, or even a hybrid version. Use traps and fans.

[@RedNeckSurgeyTech]

Very nice thanks!

[@kj7iaz]

Thanks, are you building one?

[@RedNeckSurgeyTech]

@kj7iaz I think I may try yes. I have a trapped vertical now but it's not as resonate as I'd like. So that means lost power of course. 73 KF0ALT

[@kj7iaz]

Yeah. I like the fan dipole too. It has more bandwidth on each band. But the tradeoff is the trapped can get more bands in the same space. And an internal tuner can compensate for the narrow bandwidth. Just tune it for where tou typically use it. Have fun!

[@curtisreynolds7375]

Nice! Maybe I'll go with a trapped dipole rather than a fan dipole. My only concern is I keep hearing that trapped dipoles are much more narrow bandwidth than fan dipoles. Do you find that to be an issue?

[@kj7iaz]

The trade off is its shorter, you can fit more bands. In the same space. It's a matter of preference. The more traps, the narrower the lower frequency bands will be. It really depends on your goals. Try both, see what you think. That's the fun of ham radio.

[@curtisreynolds7375]

@@kj7iaz haha I'm going to be getting my General license soon... I was a tech plus when there was still a tech plus license... then I got out of radio for a while (like 20 years lol) and just got back in. I don't want to limit the bandwidth right when I can use wider range of spectrum lol.

[@kj7iaz]

Yeah. It typically is fine either way, bit the fan is easy to build.

[@curtisreynolds7375]

@@kj7iaz Maybe I'll do the fan dipole and just hang a few weights from the bottoms of the spacers to keep them from flipping up and around in all but gail force winds? lol. I don't know if that's workable though.

[@tangowhiskey7476]

Don’t be afraid to ditch the spacers on a fan dipole. This will solve the wind issue as most fan dipoles built this way will self unwind without the spacers. You can also put each dipole elements on a different azimuths, It’ll work just fine, and is more efficient. Give it a try. Hope to work you on the bands. 73 N9XDS.

[@bitemykrank1970]

According to Play Store, the app isn't available if you live in Australia.

[@kj7iaz]

Well that is a problem. I'll have to add Australia and get it approved. If you email me at [e-mail]. I can let you know when it becomes approved. Thanks for watching, and letting me know.

[@kj7iaz]

I got it approved already! Thanks again.

[@carlosmanuelrodriguezvarga728]

😊

[@kj7iaz]

Thanks

[@TOMMYCUETE]

would you share the link where to buy that mass

[@kj7iaz]

I got it from dxengineering.com. I have 2 videos on it. A build and an install. Check them out. I also think the link is on those videos.

[@KX2U]

Question: do you cut hair?

[@kj7iaz]

... where's this going?

[@KX2U]

Oh C'mon.... the mustache....@@kj7iaz

[@kj7iaz]

Yes. Quite the conversation peice. Haha. Make sure you check out the community section of my page. Oh and if your not subscribed. You should lol

[@kj7iaz]

Did you catch the mustache antenna build video? Hehe.

[@biluphummm]

bagaimana settingan di nano VNA untuk menguji traps tersebut boleh anda tunjuk cara nya de 9W8BIL 73

[@kj7iaz]

I just set it to read swr. all you are doing is seeing where the swr is lowest. you could use any swr meter with this method.