How to make a 40 Meter Doublet the best antenna I have used and Perfect for Elecraft KX2 / KX3

In this video I will show a DIY 40m Doublet that is perfect for SOTA/POTA with Radios with internal tuners capable of 10:1 tuning. Also great for External Auto or Manual tuners.
Antenna wire Lengths - the radiating elements are 33'5"and the feed line is 34.5' all wire is 26awg silicone jacket
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[@johnhendry7068]

Enjoyed seeing our contact! I rarely get to hear the other side of a QSO. Nice setup! 73 de KG5OIB

[@KK6USYHamRadioAdventures]

John it was great making contact with you , from my location you were by at least 2-3 s units stronger than most other POTA activators that day. What antenna and how many watts were you running?

[@johnhendry7068]

I was running 80 watts from my Icom 7300 into a G5RV Jr, up about 20 feet.

[@earlbrown525]

Good video, Chuck! One of these days we will have to meet. I walk my dogs there often and live only a few miles east of there. WB6JAF

[@survivalcomms]

Thats cool ! I have done this with WD-1A field phone wire and it rocks. Thanks for sharing !

[@KK6USYHamRadioAdventures]

I think with that radio it is the best antenna!

[@tommycheshire5508]

An excellent low cost antenna that works well.

[@nvrumi]

I built a doublet a year or so ago. I had some 16ga THHN in the garage so I built my antenna with 22ft legs and used electric fence standoffs to build the feed line. Each leg is a single piece of wire from the end of the leg to the feedpoint. I figure the impedance of the feedline is about 600 ohms, so I use a 4:1 balun to get the impedance to about 125 ohms, which the KX2/KX3 can readily match. It's a good antenna and now I'm going to build another, this time with lighter silicone sheathed wire, like you have done. If I can find any 300 ohm TV feedline, I'll use that to feed the antenna. I'm wondering about the impedance of your feedline. Well done.,

[@willian.direction6740]

Neat wire for that job, thanks for the video.

[@bobbyt2788]

Great idea! Thanks for sharing. I don't see where you showed how you connected it to the radio?

[@KK6USYHamRadioAdventures]

to a bnc banana connector

[@bobbyt2788]

@@KK6USYHamRadioAdventures sorry, I saw that but I thought you were going to show how that was connected to the radio. Unun, balun, coax length?

[@KK6USYHamRadioAdventures]

@@bobbyt2788 I used it direct to the radio, I have also used it with the elecraft 1:1 / 4:1 balun it works great with or without.

[@bobbyt2788]

@@KK6USYHamRadioAdventures wow, and you got that good of an SWR! I would have never guessed that would work.

[@KK6USYHamRadioAdventures]

@@bobbyt2788 the KX2 tuner is amazing

[@jonthebru]

I'm attempting to design a light doublet or dipole with coax to suspend across two points about 200 ft apart. It needs to be able to handle about 3 to 500 watts SSB.

[@WJ6FRadio]

Outstanding video! Dig the size and weight of the antenna! I have a G-90 and thinking about getting a KX2. Keep up the great work!

[@KK6USYHamRadioAdventures]

Thanks Craig for the comment and watching, that antenna really works great probably with the G90 also!

[@porkyfedwell]

Fun to watch. Of course just because it will "tune up" to a decent SWR on 80m doesn't mean it will work as a transmit antenna on 80m.

[@rickgrimes9241]

Another great video - I’m jealous of your lifestyle dude 😎

[@K4MJV]

I just sold my KX2 and I am sure I will regret it soon. I do have my KX3 though so I am still QRP ready. Thanks to your video I just ordered that balun from Elecraft. Thanks!

[@KK6USYHamRadioAdventures]

The balun was a fun build and it seems to work well. I don't think I will ever get rid of my KX2 it just hits all the boxes for me as a QRP radio, size weight and a great tuner so I can use the doublet.

[@N8XMD]

Thanks for sharing Chuck! Great video!

[@TheSmokinApe]

Awesome stuff, I want to try one of these 👍

[@KK6USYHamRadioAdventures]

Ape you should really try this antenna with your Xiego super easy to make lite easy to deploy. It beats using a linked dipole and having to let it down and back up to change bands and with my experience just as good if not better , it's what I use at home for the lower bands just a more heavy duty setup with 300 ohm ladder line, thanks for continuing to watch and comment!!!

[@KK6USYHamRadioAdventures]

@@TheSmokinApe sent!

[@donizzo8884]

Another great video for us QRPers at all levels. I can build up my options for my KX3 in the backyard and in the field - W1FYG

[@KK6USYHamRadioAdventures]

Don I use a Doublet at home for the lower bands also, it's a great antenna for the KX's with the tuners easy just hit the button and it tunes.

[@donizzo8884]

KK6USY Ham Radio Adventures So far I have used my SOTA Beams Linked dipole, DX Commander and Eagle One Antenna with good results...can’t ever have enough antennas. Flexibility is good

[@GoAmateurRadio]

KK6USY, I’ve made a few 22’ doublets with no problems but the latest one won’t tune 40m and it’s 125’ leg to leg with 50ft of feedline much like the sotabeams portable doublet bit larger. I’m using a 4-1 balun, 100w from a ftdx10 and an MFJ-929x I use a comet flat window pass through and a short run of coax to my tuner. I shortened the 600 ohm ladder line by about a foot and tuned once on 40 m but not anymore. It tunes only on about 3923 pm 75m. It’s not touching the soffit or gutter. Nate W4NDK

[@AA0Z]

I've even had luck with hosting one end in a tree and laying the other side on the ground with attaching one of those banana plugs directly to my KX3.

[@KK6USYHamRadioAdventures]

Yea Kyle they are pretty amazing on how well the y work Even QRP, Thanks for watching.

[@Swamp-Fox]

Nice! IMO doublets are a great antenna option to have in your quiver.

[@mikemiles3068]

Good video Chuck❗️I have a Xiegu 6100 on order and should be here by the end November and I am building a few little antennas to try out and I think I will build this one and give it a try❗️ Thanks you good videos. 73. KV5P

[@MrLittlmike22]

hi there - this is aFANTASTIC idea I wil definately eb trying that wioth speaker wire! can I ask one question though how do you keep the separate feeline wires all at theor pl;ace? is that ehat shrink? with? without glue ?? looks liema real nice set up!

[@KD9ZHF]

Isn’t a doublet with ladder line or open window wire?

[@michaelvk6mmb901]

Appears to be very similar to a Norcal Doublet (norcalqrp.org/norcaldoublet.htm )that I have used with great success on many a SOTA and WWFF(POTA). I use a 10m SOTA Beam fibre glass pole, but I only use it to 9mthough. In 2015 I did a 10000Km trip around VK6 doing Parks and Peaks, and the only issue we found was that if you go above 25w you get a lot of RF feedback, solved by dropping a 4:1 balun in. It's also cut for 40-10m but we have had it work well on 80m. Hope to work you when the sun decides to wake up,73 from VK6MMB

[@KK6USYHamRadioAdventures]

Yes Michael very close outside of the computer wire, which being seperated a bit could help on the feed line . I did take the time once to seperate the 2 feed lines about the same distance apart as 300 ohm ladder line but just made it bulkier. Thanks for watching and yes lets make a contact soon, from home i do pretty good to Australia ! 73

[@sonarmb]

@@KK6USYHamRadioAdventures I forgot to add...I use a KX3 for portable ops...BLOODY BRILLIANT little radio. IC 7610 at qth on a SteppIR Urban Beam ( I call him "Karl")

[@anderskihlelb3bj835]

3s in Noise portable? Normaly i have 0s in noise portable

[@CharlesTersteeg]

any update to this antenna?

[@sparky42]

you should have called this video " taking SWR readings " because it had nothing whatsoever to do with an antenna building tutorial

[@rs4425]

agree.. was hoping to see some antenna build..but...

[@mediamike693]

+++++++++++++++INTERESTING !!!++++++++++++++WORTH TRYING++++++++++++

[@KK6USYHamRadioAdventures]

It works great! You need a good tuner like the kX2@3 or add on for the IC705

[@redman840]

What are both the radiating wires,and feedline lengths?...Tnx & 73...de W7KB.

[@KK6USYHamRadioAdventures]

redman840 it's in the description above. 33'5"and the feed line is 34.5' all wire is 26awg, Thanks fro watching 73

[@redman840]

@@KK6USYHamRadioAdventures I saw that later,after posting.Mentioned was the radiating element lengths,but I've heard variable lengths for the feedline can be used.Thanks for info.I'm from the East Bay area,so I know exactly where you were operating from.Great video..keep the camera rolling.

[@KK6USYHamRadioAdventures]

@@redman840 , Yea there is a formula for feed line lengths but i got lucky and this worked lol. Yea not the most scenic beach lol but its close, I want to do the DX Commander there one of these days!

[@douglassewell5856]

Do know the formula for feedline lengths please I know antenne is 468/freqency but nothing for feedline@@KK6USYHamRadioAdventures

[@romanomorelli2831]

I’m wondering without spreaders for true ladder 450 ohm line how well your feeder line works without them ?