HF Antenna - 40 - 10m Self Build EFHW

[@Alvin-we3mt]

If there were ever an award for the best video about simple, low cost, HF antennas that anyone can build, Peter Waters should receive it for this amazing video. The clarity, pace, and completeness of the information sets it apart from most others I've viewed.

[@watersstanton]

Wow, thanks!

[@JocMe-c9h]

THANKYOU. New HAM here, just built one and throwing it up in the air tomorrow morning. Thankyou again from Australia. 73.

[@toddshook1765]

Thank you for demonstrating the construction of an UN-UN. Just took the mystery from my mind.

[@watersstanton]

Glad to help

[@thestonerguy5276]

Timely Video Peter! Your instructions and advice are always extremely welcome. Thank You again. 73

[@watersstanton]

Very welcome

[@brianfields4479]

Thanks for sharing Peter, great video. No, I have never bought a ant, but I have made quite a few, including this one. 73.

[@watersstanton]

Cool, thanks

[@LouiseBrooksBob]

This is my favourite antenna for portable operation. Just one 6 metre roach pole, inverted V, I have worked Argentina on 6 watts upper side band.

[@DonDegidio]

Hi Peter, Great info in the video, however I counted 15 turns on the UnUn several times to be sure. That would make it a 56:1. I believe the rule is every time the wire passes through the core it is a turn. I'm interested in why you started counting at zero. 73 WJ3U

[@hansblommers6088]

@hansblommers6088 10 uur geleden The point where the wire, connected to the shield of the coax first touches the firite core is the starting point of the first turn, Peter calls that the 0 point, the next time the wire passes that exact same point on the core is 1 full turn. Counting the times that the wire passing though the core is not correct. Peter explains it at: 14:12 min, also that the amount of turns is a bit over 14 due to construction. So the impedance transformation will be somewhere between 49 an 56.

[@wd8dsb]

You are correct, he definitely has 15 turns. 73, Don wd8dsb

[@mortimersnerd801]

... it's not that big a deal... many antenna installations will match better at 15:1 (mine does) ... there is no fixed rule about this...if at resonance the vswr swings down to say... 1.7:1, and you are using a 14:1 turns ratio (2400 ohms), try a different turns ratio and you might well get a better match. EFHW antennas can exhibit varying feed point impedences depending on hight above ground, wire configuration, or ground conductivity. 13:1 might even work better... ya gotta experiment.

[@electrolytics]

Love this channel for easy to grasp Ham Radio tips and builds. Very PRACTICAL. Thank you.

[@alandrury9955]

Great antenna. Use one myself and have built several others. Regarding the counterpoise/earth, the key thing to grasp is that the outer of the coax you're feeding it with IS the counterpoise - you don't need one because you've already got one! As long as your line isolator is at least a few metres down the coax away from the UNUN then it works just fine. Great for field days and portable use, and great for those with an upstairs shack where an earth would be problematic

[@1oldtexan922]

great info, love the laid back style of presentation

[@watersstanton]

Glad you liked it!

[@davidwalle5025]

Good video. I like your method of winding the transformer very straight forward

[@ThumpMaster6]

Glad to see you coming to the iPhone video revolution Peter...and your timing was perfect with this one, as autumn is POTA & outdoor activation season! EFHW for the (portable) win!

[@watersstanton]

Great.

[@vironpayne3405]

Peter, another excellent video on a great antenna. The EFHW has been my #1 goto antenna for about 10yrs. Currently, I'm building my first autotransformer for an 80m-10m EFHW. I was inspired by Colin-MM0OPX and his use of a different ferrite geometry that yields higher efficiency. Enough other builders reproduced his results so I decided to proceed. All my HF work is portable and most of is QRP so I wanted high efficiency and a winder. A buddy, Bob-W3RDL, volunteered to use his laser cutter to make a winder. As efficiency is important at QRP I am going for few tenths improvement with taps for 49:1, 56:1, and 64:1. What makes the my goal a tad more difficult is I'm trying for higher Q in the voice portion of all the bands. That means playing with four variables. Antenna length, inductor about 2m from the feedend of the antenna, capacitor value on the transformer, and capacitor in series in the antenna about 32% from the feedpoint end. As I operate portable I wanted to use as small of a diameter core as possible. Unfortunately, a nominal 1/2" pvc pipe former didn't work. A 3/4" pvc pipe coupler with an O.D. of 1" 1/8" and pill bottle with 1" 9/16" both have worked. My higher harmonics above the baseband of 80m are looking nice. 10m has its minimum SWR at 28.5mHz. The other bands except 80m are looking good. 80m is about 6.9mHz so its time to add the in series capacitor. On the transformer I started with a 120pf 3kV TDK ceramic disc capacitor. As part of the tuning process I ground down the capacitor trying to get the 1/2" pvc core inductor to work. As grinding down the capacitor and lengthening the antenna seem to reduce the Q, I may use the 120pf capacitor again with the larger diameter inductor. At any rate, even though the antenna is not quite ready for primetime, I still had my best QRP day ever the first time I used the antenna. From the SpaceCoast of Florida, Tom Stratham Park, Titusville I made several contacts into Europe on 10m and a couple on 15m. 5 or 6 were on QRP 10W ssb phone. A couple were at 20W and one at 50W. I got Croatia, Slovenia, France, England, Germany, Spain, and a first for me Russia. I worked 40m-10m with several stateside stations, mostly POTA and special event. The bands were STELLAR! I'm not an electronic person by trade, so I've been relying on my NanoVNA with an empirical hunt and peck method to get things dialed in. As I take paper notes its been a bit slow, but fun! I concur, an EFHW antenna is very hard to beat!

[@andre4z620]

Thank you for indicating the measurements also in the metric system

[@watersstanton]

Yes I get slammed if I don’t include metric. And yet we still have 2” pipes and 4” screens! 73

[@Majorme2]

Howard here in Kentucky,USA. I’m enjoying your vids…and I’m a novice…

[@watersstanton]

Great to hear from you Howard.

[@AlvinMcManus]

Great video! I have a question about the CM choke you speak of; is that necessary if you connect the antenna coax to a bulkhead connection that is mounted on a copper plate on the 8ft ground rod outside the shack?

[@GaRbAllZ]

I will give it a try! Thanks

[@reedreamer9518]

I've never owned or used a store bought HF antenna - what fun would that be?

[@TheDk3bi]

Thank you very much for this very practical instruction. But, I have a question about the number of turns on the core: I have learned that one wire going through the centre of the core is regarded as one winding. If I counted that correctly, in your auto transformer there are in total fifteen wires going through the core. Between the ground end and the tap I count three wires. So in my opinion the winding ratio is three to fifteen. That is an impedance ratio of 1to25. I have been using such an EFHW for some months now and I found that in practice a lower ratio than 1to49 works better. So, your 1to25 ratio might be an improvement.

[@watersstanton]

I have compared my version with a couple of commercial designs and the only difference is a slightly difference in frequency response. Across 2.5K load they were identical.

[@michaelharkey9675]

de KI5DPA. Will the ferrite support 160M if the antenna wire is long enough? Thanks for the good presentation of tinned copper wire!

[@alexmonaghan4745]

You mention using a longer line to get 80M, will this scale up to 160M as I have a nice long garden

[@timh3178]

Thank you for the most helpful explanation about the coil winding! And which of your videos explains about "line isolator"s? Thanks.

[@muddy11111]

Nice video. It would be good to have a review of your linear power supplies, as there is no information readily available for them. Have tried asking W&S, via the web page, but no reply. Having purchased an FT-710 from yourselves, which I'm delighted with, I need a bigger power supply to use it's full potential. I've seen your video on switch mode, but I suspect a linear would meet my needs better. Keep up the good work.

[@paulsengupta971]

I've used mains twin and earth wire to make un-uns in the past. Works great. I've used enamelled copper for my latest ones as I've used Colin MM0OPX's preferred torroid for best efficiency, and the turns are closer together/touching on the inside, so need insulation but not as thick as the mains wire PVC insulation.

[@hikingfish3]

Such a pleasure to listen to. Very well explained. Could I use a 64:1 instead of a 49:1 and use the rest of the details given in this video to make a 40-10m antenna? I will be using a tuner. The 64:1 are readily available on Amazon and I'm not that interested in building my own at the moment. Appreciate it!

[@watersstanton]

Yes either will work OK. I prefer 49:1 but others s may disagree!

[@dieselbushcraft1299]

After Peter, will W&S be at the Hamfest next week? If so will you have some Ferrite Cores with you. Thanks

[@JamesGoodwill-z1s]

Hi Peter, excellent video, as usual. I'm putting up a 40m EFHW for my home station. With regard to a 1:1 line isolator, should I have one at the feed point as well as at the transceiver end of the coax, or will one at the transceiver suffice? Thank you for all your efforts in putting these videos togther for us all. James.

[@watersstanton]

No, don’t. use one at the antenna end.

[@JamesGoodwill-z1s]

@@watersstanton Will do. Thank you Peter. 👍

[@paulsengupta971]

You can use one at the antenna end if you also put in a counterpoise wire, but in that case I'd probably want one at the radio end as well.

[@davidportch8837]

another great, practical video peter... many thanks...

[@watersstanton]

Glad it is helpful .

[@johneckert1690]

You talked about using 67 feet of wire for the EFHW antenna on 10, 15, 20 and 40 meters., and it just so happens that 67 feet is a quarter wave in 80 meters so if you are like me and stay up all night due to your work schedule you just bypass the un-un. As always please check your VSWR before proceeding. On a personal note Peter, how is you wife doing? If I remember correctly, I think you stated she had mouth cancer when I told you that I have stage 4 head and neck cancer. My XYL and I are keeping both of you in our prayers.

[@watersstanton]

Many thanks for your prayers. She is well on the way to recovery and just able to eat soft food. We will both pray for you. God bless. Peter.

[@mktwatcher]

Nice video. I think I will make this. However, can you pls clarify your comment about using a Line Isolator just before the first piece of radio equipment at about timestamp: 19:38 is that different from a lightning arrestor? If not, can I add a lightning arrestor and where would it go? Thank you

[@rossbassette7518]

A lightening arrestor is a different item and self-destructs with a catastrophic electrical surge . A line isolator helps prevent common mode current from going back to your shack while you operate

[@watersstanton]

Line isolator can easily be made. Use a similar ferrite core and weave around ten turns of the coax feeder around it. Search on my site for line isolator. Cheers. Peter

[@JH-jp9sv]

His reply for a line isolator is spot on. If you head down to watersstanton and want to buy one off the shelf you might want to ask for a 1:1 current balun.

[@cliveharding1825]

Where can I get a core in the UK that wont cost a few 10 of pounds? Toroidal seem to range from a tenna up but ‘ferrite’ seem to start at over twice that? Add packing and maybe import tax and , you guys must be able to offer a more realistic option?

[@alanrobnett336]

I use 20 meter of washing line (steel inner) from asda £1:50p and use a terminal block to connect to coax

[@watersstanton]

Thanks for sharing that.

[@ROBByJONEs-2]

Peter id like to request a specific subject on a future video please. its related direct to this 49:1 [ish].. tell us or show us how to determine turn winding for irregulat transformers like 600 ohms to 50 for balanced. or just general how to for bal or single wire..i underastand 2 in 14 is 7 then 7 sq is 49:1 etc but turns ratio please on ring please..im nit making myself clear sorry. instead of just math show how that comes out in real world winding..ty Sir. i love your stuff as always.5 star stuff

[@watersstanton]

Hi there. If you search on Google for RF transformer calculator there are a few you can use.

[@Robbyjones-t8h]

Ty Peter..ive found some. Ty

[@CamilleCullen-ow6qj]

Very nice video, many thanks! Robert K5TPC

[@watersstanton]

Thanks again!

[@HamRadioN0CKL]

Could you do a video sometime that explains why some hams say a yagi is better than an efhw for example? I get that you can get dbi gain in a given direction with a yagi, can dbi gain not be achieved with an efhw?

[@watersstanton]

I think you have answered your question. Yagi antennas have forward gain and rear suppression . EFHW has neither

[@HamRadioN0CKL]

@@watersstanton but is a yagi only better in directional gain? Does an efhw have an advantage in other ways that a yagi doesn't?

[@andye2005]

@@HamRadioN0CKL A Yagi is usually single band and directional, so you have to "aim it" in your preferred direction. HF Yagi's are usually electrically shortened with tuning coils. to make them rotatable, but they are still big lumps of alloy. The EFHW is multi-band and can be bent into all sorts of small spaces. I've only got 30 ft or so length to the bottom of the garden So the EFHW bends back on itself in a lazy V I also have a coil to at the end to enable me to add 80m with is a few feet of wire rather than another 20m of wire. It works, not well but it gets out of 80 and is better than nothing, The Yagi will normally give a better signal in its main direction than the wire. But if you can't fit a yagi in your garden that's a moot point 🙂 Andy

[@HamRadioN0CKL]

@andye2005 thanks 👍 I ask because i see so much hate on EFHW Antenna. Especially when you even mention the idea of using an amplifier with one.

[@garygogo9048]

How crucial is the capacitor size? I have a 100pf 20kv laying around, would that work?

[@ChaplainDaveSparks]

I have noticed a few EFHW kits that say *_10-40 meters,_* but I'm not sure why, because they are just an UNUN and winder. Why not 80 meters with an appropriate length of radiating wire? I was wondering if the (supposed) limitation was due to either the value of the capacitor or the ferrite mix used. *73 de AF6AS*

[@ThumpMaster6]

@@ChaplainDaveSparks There’s no difference other than doubling the radiating length to 40m, plus or minus for finding best resonance points. Cut a longer wire, and either work well in inverted L configuration, giving you vertical and some-directional properties.

[@watersstanton]

It will also work fine if you use 40m of wire as an 80 - 10m antenna. I think I mentioned this in the video. Have fun.

[@LouiseBrooksBob]

40-10 metres is more manageable particularly when portable when you will most likely be working during the day when 80 metres is less suitable, but for winter with the long nights, and at a home QTH with a big garden, why not?

[@ChaplainDaveSparks]

@@watersstanton I understand and believe you. I was just wondering why sellers of _EFHW kits_ don't seem eager to make that claim. *73 de AF6AS, Southern California, USA*

[@JH-jp9sv]

@@watersstanton FB and a good video Peter! For an 80m EFHW you may want a tiny bit more impedance in the form of a coil of about 4.5uh 2m form the coax end. I often make the antenna out of magnet wire and 3D print the coil form for the near end. 16 or 17 turns on a 20mm form are fine. This brings all the higher band resonances closer to ideal. Edit to clarify: 2m from the coax on the antenna wire itself.

[@georgeholman6745]

What is the material (i.e., mix 31, 43 or ??) and size of the toroid core? - I got to build one of those!!! 👍

[@migsvensurfing6310]

Start of the video gives you the answers.

[@georgeholman6745]

Thanks for pointing to the info for me. I don't know how I missed that.

[@JH-jp9sv]

Material should be 43 type. Bigger size means more power handling capability and know that you may need a turn or two more on a smaller 140 to get the same result.

[@mariemccann5895]

What do you mean by a 'line isolator'?

[@watersstanton]

See text link below video.

[@mariemccann5895]

@@watersstanton Many thanks, I've just made one and I'm working on the EFHW. Thanks for taking the time to post these videos, they are excellent.

[@pierrefchenier471]

Would a 2.4" mix 31 toroid would work as well?

[@watersstanton]

Never tried it. But 43 mix or higher is recommended.

[@walterpearce3104]

Sure, but keep in mind that mix 31 favours the lower bands (160-40 meters). SWR at 20m shows a small rise but still acceptable. I use a pair of stacked mix 31 toroids in my 49:1 transformer, using a 21 turn secondary with a primary tap at 3 turns. (Extra turns increase the inductance for 160/80 which raises efficiency with less core heating. Give it a try. de VK2ACE

[@JimNyke]

Everytime the wire passes through the hole in the toroid it counts as one turn. What you have is a ratio of 3 turns primary, to 15 turns secondary. This is a 1:5 turns ratio of this unun. This is a 5x5=25(square of turns ratio), and is a 1:25 unun, NOT a 1:49. You need to correct this, as obviously many will have tried this and it will NOT have worked correctly. The 1:49 unun will be a two to fourteen turn ratio = 1:7 turns ratio and 7x7=49(square of turns ratio), and will be a correct 1:49 unun. (unbalanced to unbalanced) 73s

[@vfcs]

Why does it look like your UNUN has 15 rather than 14 total turns?

[@pixeluser175]

1:09 Music

[@lifegettingintheway2710]

That appears to be a 3/12 autotransformer.

[@watersstanton]

No.

[@lifegettingintheway2710]

@@watersstanton My silly error - I meant 3/15 autotransformer and thought I wrote that (I have double vision after cataract surgery). Arrived at by using the convention of counting the turns that pass through the core center. That would be a 25:1 impedance ratio.

[@birdhouserocket]

Always very practical, common sense and great explanations from you Peter. Thank you so much. I would love to hear you talk about magnetic loops. With weather turning cold, that could be a great indoor build. Thank you again and 73. de KE8TBM

[@watersstanton]

You are very welcome. Thanks for your support.

[@kd8opi]

End fed half waves are one antenna I’d never build, because the cost to buy the individual pieces of the same quality of whole assembles companies like Par (Vibroplex) is equal if not greater. Before MFJ went out of business a few months ago, they were still selling good EFHWs for $50. I bought their low power, 25w EFHW for under $40 in 2021. Additionally, you can get an EFHW with a trap that will take the length to 40’. One antenna I would (and just did) build is the VE7CA multi band wire Yagi. Now I have a 2 element beam on 20, 15 and 10 pointed west from my house in the eastern US superior to my EFHw…as long as the station is west of me. Build what you can’t buy, and vice versa. I won’t say it was easy, but it’s worth it.

[@paulsengupta971]

The problem is that a lot of commercial EFHW transformers use the FT140-43 torroid which really isn't up to 100W. For this version you can actually make it for less as the torroid is only a couple of quid. Making your own, you know exactly what torroid you have (there's a more efficient version than the FT240-43, see Colin, MM0OPX's channel - some commercial manufacturers are starting to use this torroid now).

[@kd8opi]

@@paulsengupta971. Ko4FSZ makes And sells quality EFHW’s from his website. Check it out. They cost about $70 bucks and they’re well built. I can’t quibble with people who want to build their own so that they know exactly what their stuff is made of. But that’s more of an argument from emotion than logic. Building your own hundred watt and fed half wave antenna using high-quality antenna wire that cost $.50 a foot will always end up costing you about 70 or $80 because you’re paying retail prices at a crazy mark-up for the bits. My argument is buy one unless you have the extra wire sitting around. You don’t save any money, Amazon charges $15 here for a single 240-43 core, that’s crazy.

[@kd8opi]

Hi, you’re probably right about the toroid. Even so, I think buying the pieces individually end up costing you more than just buying one that’s commercially made. MFJ used to make inexpensive versions that were quite good, my 35w version cost me $40. There’s no way you could beat that. They are still selling their remaining stock, but prices went up after the pandemic and now they’re about $80 or so. There’s a new guy selling quality EFHW’s for $70-80, KO4FSZ. He’s at a very good price point because he’s basically selling them at what you could make them for at home, but he’s probably building them for less than half of what he’s selling them for because he’s getting the materials wholesale. He has an impressive variety of EFHW’s, including POTA friendly, 25w versions on 3d printed winders. Very cool. He uses FT240-43 torroids in his transformer kits too.

[@paulsengupta971]

@@kd8opi "There’s no way you could beat that" If it's based on an FT140-43, you could make it for maybe a quarter of that...depending on the wire the antenna's made out of.

[@kd8opi]

@@paulsengupta971 I just don’t think you can. Let’s say you can get the toroid and the box for a total of 10 bucks. I think that’s cheap and I can’t find online pricing that will let me do that but let’s just assume you can. High-quality wire that’ll stand up to storms is about $.50 a foot, about 70 feet, so you’re 35 bucks for that, $45 total. Now you need a coaxial cable connector, additional wire to wind the transformer, some connectors and hardware for inside the enclosure, and a little capacitor that you’ll be over-charged for even if they sell it to you for $1. Best case scenario, with the toroid that even you don’t like, you’re at 55 bucks. Honestly I’d rather pay 20 bucks more and just not go through the hassle of building.

[@LouiseBrooksBob]

I wish 30m and 15 worked together with an EFHW. They would be a good combination for portable CW operation but 15 doesn't seem to work harmonically with 30. Unless anyone has done this and knows a trick for getting them both on the same antenna.

[@paulsengupta971]

Can't you just use another bit of wire? Use the same un-un. Should be around a 15m piece of wire for a half wave on 30m. Should also work on 15m and possibly10m if you also use a compensation coil. Ok, that means you can't switch easily to 40/20.

[@jomckarth4836]

nice, i like these tutorials, thank you! btw; can i insert a coil 110uH for 80m at the end of the 20m wire and extend with a wire about 1.5m for adjust?

[@watersstanton]

Yes you can!

[@johngriswold]

I’ve built two this week! Tnx/73 KK1X

[@larrychristensen5917]

What is the difference between an autotransformer and transformer? I have been using the auto with great success. Larry NA0F

[@watersstanton]

Direct coupling as against inductive coupling.