K6ARK Matching Unit Kit Build - End-Fed Half Wave (EFHW)

Easier to build, versatile, and effective, the K6ARK QRP matching unit kits are now available. Here's how to build it as an End Fed Halfwave.
First things first, if you're building one of these kits, be sure to carefully read and follow the instructions at www.K6ARK.com. Kits can be purchased through Amazon. Here are some affiliate links:
Male BNC Kit: amzn.to/3G28lfD
Female BNC kit: amzn.to/3zhepOq
Build the kit into a matching unit of your choice, add wire, and get on the air.
If you have any questions or issues during your build, please contact me directly and I'll do my best to help you succeed in your build. Thanks for watching, and have fun with the build!

[@nvrumi]

Very well done design improvement, Adam. This will make the build a lot easier than the old kits. You're an excellent teacher, Adam. Your explanations are very clear. 73 de AG7TX

[@TheTechPrepper]

Very well done, Adam. What a beautiful DiY kit and project. Keep up the good work!

[@averageguysradio]

Nicely done Adam, IMHO this is one of your best build videos. I built a version of this antenna based on your previous vidios and couldn't be happier with it. It bagged me my first SOTA DX in to Guadalajara Mexico. Keep up the great work/content Adam. 73

[@rfdave3980]

Wow Adam your engineering is showing, fantastic design. Nice idea using the PCB and BNC PCB mount. 73

[@vaamorais]

Hi There! Greetings from UK. Great video and really happy to learn you came up with a way to make your design available to purchase. First time I saw you build one I said to myself I will struggle with the tiny capacitor directly to the BNC. This KIT makes everything easier. Thanks.

[@45auto]

I'm going to need Professor Farnsworth's glasses to see that capacitor. 😀

[@nathansharp9957]

Definitely will not need the finglonger to grab it though

[@motorvids]

Everybody should buy and make one of these. Adam's channel has been a great inspiration to me. He is a great teacher and very innovative. I have made several items based on his videos and been very successful in the QRP arena. Amateur radio operators need to support people in our hobby like Adam. Thanks for this video and I just placed my order. Well done! KJ7PRS

[@ianmcqueen13]

Wow! So much easier than doing it from scratch. Following your previous video, it took at least 4 tries before I go a working model. But the pride!

[@SteveYancey]

I’ve built a few small ones but I always liked your original build so I ordered a kit. Im looking forward to using it.

[@michaelharriman6080]

I ordered before even starting the video. Built the original version for 20m and gave it to a friend for their QCX. Will build this one for 17m for my QCXmini. Congrats on the kit release. I’ve missed your videos.

[@PortableRadio]

I built and tested a bunch of different EFHW couplers and yours ticks all the boxes for minimalistic QRP in outdoors. Your previous KZbin video, in which you built the 1:81 transformer was really innovative, that's why I linked to it in my EFHW document. This kit makes it even easier to built this kind of versatile antenna and still allows to play with different radiator designs. Well done!

[@JnJTrueOutdoorAdventures]

Thank you for providing the kit! I just ordered one! I never got around to buying the components myself to try and build it back when you had your video of how to build them. So glad you put this kit together. Juddie - WD8WV

[@wild-radio7373]

Fantastic! Ima tell everyone in my club about these♡ although, a few of them already probably ordered theirs! Really appreciate your work!😎👍

[@Bill-HRT]

Awesome! I'm building a bunch so I don't worry about losing the one (because I really like your design) I built from your video months ago.

[@martinhuyett7502]

I built the 9:1 version today. Messed up the toroid winding! But found 3 colors of same sized wire and wound 3 separate windings. Colors made connecting them easy. With 29 ft element and 17 ft counterpoise tuned nicely and had 3 POTA hunter QSOs on 40, 30 and 20 at 5 watts CW. Got good reports. Thanks for good kit!

[@craigsharples6324]

Awesome kit, will be ordering a couple shortly!

[@harpmatt100]

I BUILT up mine this afternoon. Wonderful. It really works. Endx halfwave antennas are great. I have experiences with Fuchs antennas. You only need a short counter poise ore even none. That's the advantage of these kind of antennas. I like that antennas.

[@mattghoward]

nice - like the use of the board mount connectors - I built the original version grinding away the connector :-)

[@jeremytanzer279]

I've got a couple on the way. Can't wait to have my own K6ARK antenna!

[@acestudioscouk-Ace-G0ACE]

An excellent video, lots to learn and good tips even if you don't buy the antenna, which you should.

[@daniell8387]

I can't wait to put mine together after work today! Funny I had most of the components except the board and the BNC Connector

[@obiter-things]

Hi Adam, great kit and great video. I recommend one additional step before soldering the BNC: Do a continuity test to check that the enamel has actually burned off. Desoldering and resoldering the toroid after the BNC is in place is a real bear-I learned the hard way, 😂

[@moistmoustache420]

Just bought one of these bad boys .. super keen to give it a go

[@gliderrider]

Ok I got one. Hot dang, it works! I screwed up and tried to save money buying Chinese wire instead of ‘wireman’ silky wire. So I tuned it to be droopy so as not to stress out the cheap wire. Still works! Added a piece of 20’ coax. Still good on 20 and 40 meters. This is great!

[@tortellini-doodles]

Excited to build this today, thank you!

[@Medic-ui9ms]

Just ordered a kit, looks like a nice little winter project. Thanks for the video! 73, NJ0Q

[@mattghoward]

Just built this version - sooooo much easier lol thanks - goes well with my qrp field kit

[@ChrisN8PEM]

Just finished my EFHF Build. Total finished length 61.5'. Flat 1:1 SWR across 40, 20, 15 and a good chunk of 10. No Coax - direct to radio. My tip: I placed a loop of paracord thru the small loading coil and use that as my lash point on the radio end.... the 6' of wire between that and the BNC are then 'loose' for connection to the radio. Thanks Adam!

[@DK5ONV]

Happy New Year into San Diego County... 💯🎸🙋‍♂

[@K5YVY]

Awesome build Adam.

[@michaelmcghie]

Thanks Adam for the well put together video. Being new to building an antenna, this will help for my first. 📡

[@K6ARK]

Please follow the written directions as the build process has been modified a bit. The updated toroid winding method is a little easier and the boards were updated to accommodate for additional build options.

[@Pabloisradical]

My kits in the mail, can’t wait to get it

[@mountainwalk1169]

Just ordered. So excited

[@owlcricker-k7ulm]

Glad te see your ME skills and creative juices flowing. 72 OM

[@frankalvernas6628]

Awesome! I enjoy your videos very much, especially the antenna build ones. keep up the great work and more videos coming...73 de N6LPV

[@vincei4252]

Happy New Year, Adam. All the best with the kit!

[@K6ARK]

Thank you, Vince, I hope builders love it and are successful with their builds.

[@Mottersmotters]

Happy New year Adam to you and you're family. Great video. Motters M7TRS 73 👍🏻

[@ChrisN8PEM]

He's Back! It's been too long Adam! I just placed my order. Been waiting for this or a long time. Instructions look great!

[@K6ARK]

Thank you, Chris, and thanks for the Christmas letter and bookmarks. What a brilliant idea. I love it. Sometimes life gets busy and it's hard to keep up on video production and editing, but I'm definitely still around and creating. That won't stop any time soon even if it is a bit less frequent.

[@ChrisN8PEM]

@@K6ARK No problem! Thank you so much for putting these kits together. I can't imagine the work involved to get to this point. Hoping with this kit to 'lose the coax' in the future lol.

[@kodyeliason1389]

Finally! Love the videos! Just ordered two!

[@K6ARK]

Thank you, Kody! Please reach out if you have any questions during the build. 🤘😁

[@RevGunn-jq3cq]

Nicely done!

[@m.p.6330]

I have 2 that just arrived. Thanks for making these available. I can't want to build them.

[@GigaBrand]

Whoo just ordered one last night!

[@bubbleheadft]

I've got my kit and I'm hoping to pair it with an FX4C sometime in the future for an ultra-portable rig.

[@nickrupp2336]

Thanks ! As soon as I seen this video I went straight to Amazon and ordered 2 of your kits.

[@K6ARK]

Awesome, Nick! Please feel free to reach out to me with questions or if you have any issues. I want to make sure everyone is successful in their builds.

[@nickrupp2336]

@@K6ARK would it be possible to make this be able to handle 20-25 watts by using a bit bigger wire ?

[@K6ARK]

Wire is not the limiting factor, the toroid is. You can add a FT82-43 toroid and nest the FT50-43 in the center, then wind it as if it is a single toroid. Works great for up to about 30-35 watts!

[@nickrupp2336]

@@K6ARK thank you!

[@K6ARK]

@@nickrupp2336 built that way, it's a fantastic G90 antenna. I may make some G90 kits at some point... 🤔

[@ON4RW]

Thanks Adam well done !

[@gregh3248]

Excellent Presentation. Thank you.

[@raithjames860]

Look back on amazon USA and was going to buy a male bnc kit there. Looks like you are out of stock already. I will wait for the next batch. Great kit, excellent videos. I'm learning a ton and starting to build. Thanks

[@K6ARK]

Just sold out! Next batch is already en-route to Amazon. Soon!

[@AA0Z]

Showing the easy build process will hopefully encourage some more builds. It's a lot less challenging when you show vs tell.

[@ambitiouslawn1678]

Awesome man!

[@K4MJV]

I just placed my order. I hope my fat fingers can get in there to build this antenna :)

[@haroldskinner1783]

Adam would love to see a short video on wrapping the 9:1, i have read your instructions over several times, but would still love to see it done, being from Missouri, Show me 😊

[@randalltom9750]

He’s alive! I had thought you’d fell off a mountain, or you were on an extended ‘on location’ action film shoot, doubling for Bruce Willis as a stunt double. Huh, I’m rarely wrong…. But hey, I did build your kit, and hey, I love it… a 9:1 Unun with linked 20-40m legs… Bravo Adam! Now I need to figure out how to install your cap key kit into my QCX Mini…. de W7UDT Rand (dit dit)

[@K6ARK]

Thanks Rand! Yes, I get busy with life sometimes as well, but I do need to get back to making some more videos again. I also need to finish my reply to your email. I do have more cap touch key PCBs and can get another headed your way. Thanks and 73.

[@randalltom9750]

@@K6ARK Hey Adam! Here’s a heads up… I’m working on a protective laced Kydex S/POTA board for my KX2… (what the ‘he double toothpicks’ is that?) My KX2 has rails, so the top molded half of the shell will be clear, and act as a cover for the KX2, being laced together with paracord to the bottom half, a 8x12” flat clipboard… the sides of the top case will be open on both ends, extending an inch or so off each end. The top cover will accomodate the front paddle. It’ll all hang from a lanyard off my neck, so when seated, I can comfortably operate and log my contacts… whatcha think? The laced board will provide the weather and impact protection the KX2 lacks…. Being laced by paracord, it will hold the radio securely.

[@agplay2290]

Ordered it yesterday.

[@NorthCountryHam]

Very nice, I don't normally QRP, but I want to build this just to have one.

[@willian.direction6740]

HNY everyone. Thanks Adam for sharing and making your design available for everyone who wants to have a go at making an antenna. Hope to hear some dx cool waves from summits in 2022 as bands pick up. Regards Ian vk5cz ..

[@okhamradio]

Thanks for sharing this information

[@johnsinclair3067]

Just got mine. Great kit. Be careful when bending the posts on the female connector. They snap if you fiddle with them too much.

[@K6ARK]

Yes, they do. If you damage more than one lug, let me know and I'll get you a new BNC and updated PCB that fits better. Or, if you just want the PCB before building the kit so you don't have to bend them, I'll be happy to send one. All future kits will have the updated PCB specifically designed to fit the female BNC rather than the generic male one.

[@johnsinclair3067]

@@K6ARK thank you the offer. I am good - just wanted the first gen folks to know to go gently :)

[@503Nick]

I’m looking forward to using this. Should be delivered next week. Slightly concerned with the build and my old eyes 😅

[@CalSextons]

Just grabbed two kits, can’t wait to try and create one of your antennas for my SOTA outings. Don (N8FN)

[@K6ARK]

Awesome, Don! Enjoy the build, and please feel free to reach out with any questions. The build Instructions at K6ARK.com are detailed and effective.

[@larspregge6420]

Nice kit.

[@dwDragon88]

Nice kit, mine is on the way. I might suggest putting in one or two extra spare capacitors. Those SMD caps are about 10-12 cents purchased in 100 quantity or greater. People are definitely going to lose the cap, burn it with the soldering iron, etc during installation, and it would be a bummer to ruin the whole kit over that one part. I say this completely acknowledging that you've made it as easy as possible with the nice little custom PCB. Nice work.

[@K6ARK]

Good call, maybe worth it. I am also happy to send a spare (they're so small they fit in a regular mailing envelope) if someone damages or loses the one in the kit. Just reach out to me and I'll be happy to help.

[@nickrupp2336]

@@K6ARK could you just use a standard cap soldered to the pads ?

[@K6ARK]

Probably. It would be a tight fit, but I bet it would work. Just make sure it's at least 1kv at 100pf.

[@RadioRunner]

I've said it before and I'll say it again, strongest, most handsome beard in the radio game.

[@dd6fm]

Great .. just ordered .. Tnx

[@W6IWN_Radio]

I want one, EPIC!!!

[@boomerbits2297]

just built the EFRW now to test it! de ke4d your valley center acquaintance. back in the day before your time!

[@Bob814u]

Waiting on mine to arrive. :D

[@hdcd1]

Nice work! Mine delivers today. Looking forward to the build. Any other antenna builds on the horizon? Thanks.

[@washingtonstatepicker3460]

Thank you

[@bruceweight7319]

Wonderful little unit. I would suggest having a blank piece of round pcb same size as the main pcb with a notch for the wires and add it right at the end of the heat shrink process as a cap on the unit and maybe hot glue it to seal it.

[@K6ARK]

Oh, good idea. I may have to test that out. Thanks for the idea.

[@bruceweight7319]

@@K6ARK So fun to see such a light cool unit; a round piece of hard plastic would work too. I could build one for my QCX and it would make a really light small portable unit. I am curious if it was you that I saw tuning one of these types of units using a spool of wire to roll it out while it is connected to the VNA and watch the dips and find the best length. Was that You? they first strung it out and found out how many turns on the coil was best and then trimmed the length of the wire to the best swr. I couldn't remember what the procedure exactly was and have been looking for the video and can't find it.

[@K6ARK]

Nice! Thanks. That is indeed my tuning strategy. I can't remember if it's in a video or if I just described it. Regardless, it works well!

[@bruceweight7319]

@@K6ARK Thanks for the reply. If you get bored maybe do a video on tuning the core and then the antenna sometime. I am sure you get bored haha. Thanks. I am going to look up one of your units on Amazon. Looks like a great unit. I love building stuff and that includes kits. The tuning method could also be used on higher powered antenna's.

[@ErnestGWilsonII]

Thank you for posting this video and sharing it with all of us! A few questions please: 1. Is there a place we can buy a fully assembled unit? 2. Do you have a variation where you have built SO239 instead of BNC? 3. Which specific wire would you use if you were building an 80 meter EFHW? That wire is long and I'm wondering if folks have a preferred wire that doesn't tangle and is easy to manage? 4. if you were going to have a multiband EFHW, would you use a 9:1 and a random wire? Or a 49:1 or 64:1 and a half wave wire? When going multiband with 80 m as the lowest band, which of those would be the better choice? Thanks in advance and I am of course subscribed with notifications turned on and thumbs up! 73 W3GUY

[@gliderrider]

Now for that micro pixie. Or better, a micro cricket. It’s got side tone! No pressure hihi

[@kq6up]

You have to sell your Pixy in an Altoid Mini. That thing was awesome.

[@raithjames860]

I see they are back in stock. I just bought two as a way of saying thanks for all your help. I going to build some from scratch as well. Were do you source your antenna winders? Appreciate your work.

[@w2msa]

Looking forward to this build. Thanks Adam! de W2MSA

[@K6ARK]

Sweet! If you bought a kit recently, be sure to use the written instructions on www.k6ark.com. they are a little different now.

[@w2msa]

Will do. Should be a nice match with my KX2.

[@shanebaker9975]

Hey Adam, great video! Curious if you have a recommendation for a multimeter? I don't have one yet and seem to run into more and more uses for one. There are a ton out there and $ to $$$. Thanks!

[@aristotleallen5577]

Very cool little kit. Any chance you are planning on making a similar kit for traps?

[@robertpastorella]

Are you planning another round of these? Or maybe the a PCB on OSHpark? I would really like to build one of these

[@Paddy_Roche]

Fantastic job, it’s a sub from me. Happy to be aboard.

[@PaumanokSupplyCo]

What size heat shrink for the 26 gauge poly stealth? I want an extra roll laying around for additional links and banana clips. Thanks!

[@DonDegidio]

Hi Adam, Happy New Year. Excellent build video. Close-ups were perfect. I think the silicone should be the acetic acid free type to prevent corrosion. Would dribbling some hot glue affect the tuning? Stay safe. 73 WJ3U

[@K6ARK]

Thanks Don, yes, non-acetoxy silicone would be best. Hot glue should work well too, but has a lower melting point that may be a problem in hotter climates.

[@KD9ZHF]

Is there a calculator online for how many times you need to wrap the toroid with X-type of wire to get a X:1 unun for XXXw?

[@johnsinclair3067]

WOW!!!

[@ON3STG]

Hi Adam, impressed by the size and simplicity of the design. Even for me it seems to be feasible to build the kit. Unfortunately it seems to be sold out. Do you have an idea by when this will become available again (in Europe)? 73 ON3STG Gert

[@charleszimmermann7784]

Does it hurt to add the counter pose, even if you are not intending to use it?

[@iracG5]

i world love to use that new winder you show last in that livestream, please share it whit us:)

[@K6ARK]

Yes! I've been building up some stock and will have them available soon.

[@iracG5]

@@K6ARK please Share the .stl file i got myself a 3d Printer

[@87balexander]

Is the low power rating the reason you can get away without a counterpoise?

[@washingtonstatepicker3460]

Is the second video up?

[@68thBC]

Just found this video and I am a complete noob on antennae. Could something like this be built for 10m, 6m, and 2m use?

[@wolfwizard406]

I only have one hand, any chance this will be available already completed?..

[@Aimsport-video]

Great stuff. Hypothetical question ;) For R&D of windings for any higher power product… have you seen DL2MANs recent video for capacitorless winding and will you include that in your experiments? Thank you for doing such great things for the portable operations Ham community!

[@K6ARK]

Yes, but there are better ways to test as well. Check out AI6XG's blog.

[@TimHarperW5TAH]

Where can I getbthe Banana clips?

[@derektrounce937]

Will hotglue affect the matching unit?

[@ouijim]

Nice Kit. Looks like Type 43 toroid which worked well for me with 49:1 transformer EFHW. Type 2 (Red) toroid was better for me as I got better performance with 9:1 UnUn, specifically 10m and 6m on NET Nights which I do portable at times ; ) Anyway a must have in my portable setup . How much power will it handle? Thank You. . . Mostly I use T200 Type 2 (RED Toroid) 9:1 UnUn, Type 43 RF Choke, 29ft wire and 17ft counterpoise (EARCHI Antenna)

[@K6ARK]

Yes, it's a -43 mix which works well in all 3 build options. I generally recommend a maximum of 10 watts for lighter duty-cycle modes and 5 watts for modes like FT8.

[@tomkeady1750]

Adam, great job on the kits and videos. I got an assortment of toroids, magnetic wire and surface mount caps for your early mini builds a couple of years ago. Your new builds with the pcb's are super clean. Any chance you sell the just the pc boards?

[@K6ARK]

I'd be happy to, Tom. The BNCs are a little harder to source but available. Send me an email direct. I'm good on QRZ.

[@tomkeady1750]

@@K6ARK Thanks Adam, You're really on top of this. Looking forward to more videos.

[@robertaldrich2635]

I just built the EFHW version with female BNC, ready to tune the wire but don't see your video you mentioned (to tune the antenna length) at the last of this one. I guess I can experiment, someone below said 61 feet but I'll start with 68 or so. I did test it out (using the internal tuner and about 50 feet of wire) and got a weak signal report on 7.255 with my G90 on five watts. What is the max power recommended with the EFHW?

[@K6ARK]

Start with a bit more than half a wavelength on the desired frequency of operation and fold back the end of trim to resonance using an analyzer, or trim to minimize SWR if you don't have an analyzer. The standard build is good for 5w on heavy duty cycle modes and 10w of lighter duty cycle like typical SSB.

[@spencerhochstetler]

Hi Adam - thank you so much for your channel which is full of great information! Do you have any plans to "recharge" Amazon (or any other outlet) with these little kits? Thanks!

[@K6ARK]

Yes, I restock as often as I'm able. I am sending another batch of QRP kits tomorrow but they'll sell out fast. Sorry for the delays - the antenna kits are not my day job and my family, regular work, and SAR volunteer work takes priority. Lately, they have been consuming almost all of my free time. Thanks for your patience, and check back on Amazon over the next few days if you're looking for a QRP kit. More 100w kits after I get back from Dayton...

[@metaller_alex]

Great video, thanks ! Unfortunately Amazon estimates delivery no earlier then Jan 22, 2022 (I am in continental USA) :(

[@K6ARK]

Bummer! I am a small fry in the Amazon world, so the distribution of my inventory is likely very limited. Email me if you want to try to work out another quicker solution.

[@HamRadioDuo]

Adam, any change you have a contact who buys your kits and assembles them and sells them assembled?

[@Wayde-VA3NCA]

Hi Adam, I have one of your early pcb kits and have noticed no continuity between counterpoise pad and coax sheild pads, is that because this is an isolated transformer design rather than autotransformer? Intentional? (Btw ,a really fun kit!! Thanks! )

[@K6ARK]

Wayde, good find! That was an error with one of the earilier versions of the boards. Please send me an email and I'll be happy to get you one of the latest kits to build.

[@boomerbits2297]

How about using a hot glue in the toroid