Homebrew 10/20/40m EFHW vertical Antenna "SOTA"

[@WB8ERJ]

I just ordered a 10 Mtr fishing pole to build one of these. it seems to me that if you were to tap the coil you could also get 30 meters. It would obviously take some fiddling to find the right spot. WB8ERJ

[@mk1tina]

Indeed it would work

[@christopheriles1469]

The transformer you've made is 64:1 You have 16 turns on the secondary (the twisted 2 turns count on the primary AND the secondary winding).

[@mk1tina]

Correct

[@christopheriles1469]

I'm making one at the moment but have gone for 49:1 Is 64:1 a better match?

[@mk1tina]

Hard to say as I haven't tried the 49;1 on this core. I ha e tried it on a full size 80m efhw wire and it resonates well on all harmonic bands 10 to 80

[@maksymmm9446]

2EOVOV RADIO What is the diameter of the wire on the ferrite ring? I assemble trans 1:49, on the ring ft140-43, I choose components))

[@mk1tina]

I dont remember now but it's not critical

[@acestudioscouk-Ace-G0ACE]

I'm making baluns and antenna at present so it was very useful following your progress. Thanks.

[@mk1tina]

You are welcome!

[@wadepatton2433]

Finally got my 80-meter sloper of this design going and LOVE IT! I used 49:1 and it works 6-80, only really needs tuning on 30, 75, and 160. Brilliant signals! I'm going to make some more transformers and play with variations on length and shape. Learned it from N4LQ.

[@mk1tina]

Brilliant.. That's something I often think of trying sometime.. Well done and thanks for sharing . 73

[@mortimersnerd801]

Mark.. you probably didn't need the plumbers tape, you wanna get the wire wraps as close to the core as possible.... Your wire gauge size is pretty good, but the FT 140-43 could be increased to a FT 240 43 size.. because you want to avoid saturating the core, even on 100 watt SSB voice peaks. Before me now sits a dual core FT 240 43 balun I just wound, similar to yours, and I only run 100 watts from an FT 891. but I've become aware that these cores saturate far easier than many realize.. suggest you ditch the tape and get a FT240 43. I use this to feed a 130' EFHW installed as a straight line sloper... VSWR is great, nothing back 1:1 on 40 20 15 and 10 and low on 18...1.8:1 Work any DX I hear and not only just the big guns, you can always work them but I also work 50 and 100 watt stations of modest size (and means) from western North America

[@timg5tm941]

Hi Mark. Am I right in thinking that a 66 foot long wire would be resonant on 40 and become a resonant full wave on 20 and a double full wave on 10 - making all three bands resonant? I have also found that these efhw are also tuneable (if not too efficient maybe) on 12, 15 and 17. Your design is great I know as it shortens the length of the three bander to about 40 feet if I am correct - great for portable. Looking to make a version to use at low tide one very early summers morning on the local beach. 73

[@mk1tina]

AMATEUR & 11M RADIO TIM you got the right idea

[@martinhunt4073]

It looks a good solution for SOTA, would have liked a bit more technical detail and a follow up on how it performed. As for the negative remarks it's easy to stand on the sidelines and knock other work.

[@francosacco6871]

8.

[@michanoymark2109]

What is the length of the projecting wire?

[@flyboyguru6929]

Does the lack of a counterpoise cause problems with this antenna? I keep hearing this antenna will cause radiation on the feedline and your equipment, so am a little undecided if I should use it as my primary antenna or not.

[@mk1tina]

its a EFHW, so no counterpoise required.. Anyone who says they do doesn't understand efhw. Check aat5b website for design and theory..

[@mk1tina]

+mk1tina aa5tb

[@jrfoleyjr]

+Nathan Daniels Anyone who says this does not require a counterpoise does not understand that the feed line is acting as a counterpoise.

[@mk1tina]

+jrfoleyjr the feeder is acting as a counterpoise.. hence no counterpoise required

[@mk1tina]

+jrfoleyjr but u r splitting hairs

[@paulkazjack]

How many turns would it need for a monoband 15meter version??

[@mk1tina]

None. About 7.5m of wire

[@tropenband]

Variable capacitor would be worth a try, what do you thin?

[@mk1tina]

not required on ferrite cores, but useful on iron core

[@tropenband]

@@mk1tina thanks, I was just asking myself what will happen when the fixed capacitor at the coaxial connector is replaced with a trimmer capacitor 🤔 Maybe possible to optimize SWR?

[@mk1tina]

​@tropenband it would make it tunable

[@ingussilins6330]

Is posible to built end fed antennas for 2m and 70cm bands ( only receiving ), using hight impedance preamplifiers (fets, mosfets) ?

[@mk1tina]

Look up the flower pot antenna

[@scharfshutzen]

Great video on your vertical antenna . The question that I have is your unun? I have a 5/8 vertical for 20 meters and the feed point is approximately 1300 ohms. Using a 25:1 unun I will now have a feed point impedance of 52 ohms. I see that there are commercially available units but they are quite costly. Can you provide any insight as to what ratio your home brew unun is and how you arrived at the number of turns on the coil. I guess what I'm looking for is how one would construct a 25:1 unun? Thanks in advance, 72, Steve Hose KD1DT

[@mk1tina]

Steve Hose this is a LC network transformer for EFHW and is classed as 64:1. Cant help on UNUN..This antenna is around 3000 ohms. The windings are physically 2 primary / 16 secondary making it 8:1 in its simplest form. So 8x8=64:1. Take 64x50=3k the impedance the antenna presents. That's how you configure EFHW. UNUN is a completely different animal..

[@scharfshutzen]

mk1tina thanks so much for the fast reply! It does help as I think of a vertical as an end feed antenna... So using your information I should be able to wrap two turns as a primary with ten as a secondary which will then give me a 25 to one taking the 1300 down to 52 ohms. If my thinking is correct that is... Thanks again for your input! 73, Steve KD1DT

[@mk1tina]

Steve Hose yep.. you got it.. 52 ohms is close enough 73's

[@Mark300win]

Steve Hose how did you know your feedpoint impedence is 1300ohm?

[@bbmandal]

I have FT 240-43 in stock. Will there be any change in design ? For 40/20/10 m bands ? DE VU3MDL

[@mk1tina]

shouldnt be as its the same core mix

[@barrykery1175]

Very impressive. Nice demo. I used the exact same amount of capacitance and the same number of turns on a 43 core. Just waiting for the WX to get nice so I can try it out.

[@mk1tina]

Hope your testing has gone well. U can also try a multiband efhw tuner like I recently done. Both work well. 73's

[@barrykery1175]

Test done. I erected mine as a flat horizontal antenna, like you would a dipole. I dropped some RG 174 down and put a line isolator on the radio end of the coax. I am very impressed with how well it performed and matched. I put the KX3's tuner in bypass since it's not needed. I did not see you test 15 meters? Mine works great there as well. I used reverse beacon and compared the EF to my OCF40 at the same height. I got equal results on both antenna, but the OCF40 does not work on 15 meters so I did not make a test on that band. KU3X

[@davidearnest2701]

That will give you 64 to 1 impedance transformation. Seems like you found the correct combination for your endfed. Nice job. W4GSM

[@mk1tina]

Thanks David

[@Aleziss]

what is the difference between 49:1 and 64:1 then ?

[@mk1tina]

@@Aleziss 2 more turns on the secondary

[@Aleziss]

and the goal is to acheive what versus the 49:1 ?

[@mk1tina]

@@Aleziss a 50 ohm impedance

[@charlieoscar09]

Hi... is this setup for QRP only ?

[@mk1tina]

It will run to 100w with this ft140-43 core

[@charlieoscar09]

Sorry will the caps allow 100w ? Thanks

[@mk1tina]

Yes use 1kv. Ive changed my 3 for one 100pf 1kv.

[@charlieoscar09]

thanks

[@christianpaul3303]

"Is it pretty?" No. "Does it work?" Yes. "Then it's pretty!" 73

[@DewayneW4FDT]

exactly how long and what gauge of wire have you used in the antenna?.. I have a new 817ND and looking for a end fed antenna to use backpacking, this seems to be it as it covers the bands I want to use without a tuner. I just ordered the ft-140-43 core. I understand you have the 58t of enamel wire on the 20mm core, but the tail after that how long is it?

[@mk1tina]

hi. Im using 0.75mm multi strand cable, but what length I ended with wont match yours due to many variables in the loading windings and insulation velocity, transformer etc. The way I set mine up was to build it as a efhw, then trim it for resonance. Sorry this isnt the quick fix you want, but their are no shortcuts to get the best results!

[@DewayneW4FDT]

Thanks for the reply. Not really looking for a "quick fix" just trying to get an idea of how much shorter or longer than I was originally thinking the element would be. I also build antennas but have not had to wind transformer, etc.. Ive built 3 or 4 multiband hex beams with excellent results. I am still trying to figure out the twisted wire on the torroid. I understand the 7 turns then the 7 turns on the other side.. but does the twisted pair for the primary turns where does the end start and end with the actual twister wires? Does that question make sense?

[@mk1tina]

Dewayne Treadaway you r confused about the transformer construction. Take a look at the site of aa5tb for his excellent write up on efhw. Its much easier than explaining on here.

[@69pathfinder66]

Dewayne Treadaway ㅜ

[@mickel153]

hi, you have no ground for the antenna ?

[@mk1tina]

Not required on efhw

[@biringen]

An enfed vertikal as this one antenna uses the coaxial cable as counterpoise....

[@mk1tina]

+biringen correct. Merry xmas

[@kubaszurgot3050]

What kind of the core is in that UNUN? I've been doing some different UNUN's with different cores and I couldn't find the right one.... Best regards

[@mk1tina]

Its a ft140-43 core and will be ok up to 100w. Most hf stuff is best built on 43 material. You might benefit looking at AA5TB website to help understand EFHW antenna's and how to make them sing

[@ruhnet]

For the record, it isn't an UNUN, rather a 49:1 (approximately) autotransformer.

[@KuriosPC]

what size enameled wire did you use for the torroid?

[@mk1tina]

KuriosPC it's made from scrap components so I don't know what the wire is. 73 and happy New year

[@DewayneW4FDT]

Thanks for the information, made my transformer today using the same windings as you with the Ft-140-43 core. Also used the 100pf capacitor. Excellent results in 20 and 10 meters, havent added the 40meter coil or tail yet im winding it now. Swr was great on both 10 and 20 and first contact was a DX station on internal battery of my Ft-817ND. I used 22 gauge wire as my element as I will only be doing QRP work with the antenna. Thanks for the video and information.

[@mk1tina]

Looks like u r on a roll.. 73's

[@joehendrickson6815]

Dewayne Treadaway up

[@Aleziss]

you have no counterpoise or ground ? no choke ?

[@mk1tina]

End fed half wave antenna doesn't need a ground or CP as the coax braid takes that role. I use a RF choke at the radio end for regardless of antenna

[@Aleziss]

ok thanks for the reply (where I realize you already answer that below...) can I ask what do you use for the RF choke ? just coax turn or something else ?

[@mk1tina]

@@Aleziss the most versatile and effective is 8 turns of coax on a ft240-43 toriod

[@Aleziss]

thank you for the precisions !

[@mk1tina]

@@Aleziss always welcome

[@antennebuis]

I make the same balun today ,with very bad results,I dont hear anything

[@kinggreene]

this is an un-un not a balun. an endfed antenna is not a balanced antenna.

[@jrfoleyjr]

+colin humphries An end fed antenna has an impedance in the 3000 ohm reactive range especially if it is a half wave length. I have built one of these for a half wavelength wire on 20 meters for portable use. An insulator and rope hold the far end up in a tree. I use a 1/4 wave counterpoise just laid out on the ground and it works very well. You need a counterpoise for this to work at all. You need either a 1/4 wave of coax or a counterpoise wire. You dont believe me? Try isolating your antenna with a bunch of ferrite beads on the feed line just below the coil and get back to us with your results.

[@k8byp]

Bad capacitor. Caps with BLUE coating are for AC line snubbing, NOT RF. They have high dielectric losses at HF frequencies

[@mk1tina]

Thanks for the heads up

[@alalan3735]

Is that a 49:1 transformer?

[@mk1tina]

Sorry yes

[@Mark300win]

Not its not, its 64:1 16 turn secondary 2 turns primary (16/2)square=64

[@Chameleon_Antenna]

Nice video!! You can get a commercial version of that antenna if you do not have the time to build it: CHA HYBRID MICRO

[@mk1tina]

Yes but its only 25W..

[@VK3EGN1]

Brian seems to enjoy giving incompetent advice.End fed is vertical dipole, not vertical monopole, therefore there is no need for ground plane. Impedance transformer 64:1 adjusts 50 ohm coax to 3200 ohm end fed antenna impedance.Using 3200 resistor instead of antenna is good idea to check impedance transformer matching.However, it is only the first step - and actual antenna will not work as resistor did.Reason is very simple: antenna is highly imbalanced.After impedance transformer you need choke with 10 times more impedance. Ferrite beads can not do this. I use coax choke balun, made resonant close to operating frequency.BTW even 30 kohm choke will not work well, you need two of them.73 VK3EGN

[@mk1tina]

Tino Pavic A coax choke will not work for 3 bands as they are narrow

[@VK3EGN1]

Broadband transformers with ferrite torroid are briadband anly for lower impedances, not for 2400 ohm. Any type of choke is better then no choke at all. I am trying to tell you that much better things are possible with end feeding. You can check out my setup at QRZ.COM. 73 VK3EGN

[@mk1tina]

Tino Pavic absolutely but easier on monoband versions. 73 and seasons greetings

[@TheHajac]

when the antenneanalyzer go in the sleep mode just press the mode button so you dont have to put it of en on

[@mk1tina]

Thank you Harrie. I now know. 73 Mark 2e0vov

[@whittledarren4358]

antenna will be DC grounded

[@lb9yejanmorten997]

64:1 is far better -and the 100Pf wold sort it out 20-6m ;-)

[@abdula4256]

Best 73s please do more vedios

[@montageproductions]

Too lazy to unscrew 10 screws and put in 10 batteries on the analyser? Yeah me too, use a plug pack instead! Appreciate your demo thanks!

[@luckydubeinrc5165]

49 :1 , good job

[@nlo114]

2 turns primary to 16 turns total is 8:1. 8 x 8 is 64:1 impedance ratio. If it works, leave it as it is!

[@LUIZCARLOS-jh3qo]

muito legal , luizcarlos gostei !!!!!

[@mk1tina]

LUIZ CARLOS obrigada amigo

[@luckydubeinrc5165]

no pun : get to understand your mfj, it also tells you that you have too much inductance, so experiment a bit more with your toy antenna :)

[@mk1tina]

it would... its a compromised antenna as its a multi band u can't get it perfect for any one band.. check the monoband and versions and then u will see no inductance. 73

[@venturino55]

Fine job, thanks a lot!! 73 de ik0vwh

[@TheHajac]

good jop

[@mk1tina]

Thanks Harrie

[@martinborman4195]

An end fed vertical! How nice. I notice no ground planes at the base of this antenna, thus no RF mirror. The balun has far too many turns and is no way near flat. A 1:1 balun should be flat from 1:0 through to 28MHz rising to 1:2 at 50MHz, then a steep curve to 5: or more after this point. The core used it far too narrow for the use he puts this balun to. Did he put the appropriate resistive (carbon) test load on the balun before hand? Why does he need capacitors on the unit? The distributed capacitance is nulled by the reverse winding. There is no need for added capacitors. The core needs only 3 turns (4 max) for a current balun of this type. X should be well below 5 at all times. A resonant antenna should not have X as 15. Look sunshine. I can see that your garden will accommodate a fan dipole with 7 bands viz: 40m, 20m, 17m, 15m, 12m 10m 10m. Why do you mess about with this CB style rubbish? I assume you like listening to signals being many dB down? Go ahead. Take some advice from an old-timer. Fix on end to your chimney, and fix the other end to a 25 or 35-foot pole by that garage and get the feed point and balun up high as you can, and, get rid of that bloody carbon-fiber pole. It's for fishing, not amateur radio. Your choke needs to be a minimum 8 turns wound on a 152mm - 200m (6 to 8-inch) plastic pipe type former. You need to STOP RF returning down the outside of the coax braid. You could slide 5 ferrite beads onto the coax to do the same thing I use both. One more thing. Get rid of that stupid thin CB coax. You have lost 70% of your signal be for it even gets to the radio using that rubbish.

[@mk1tina]

hello Tony. thanks for your stupid comments. This clearly shows you have no idea what this antenna is. This is a EFHW Transformer, not a balun!!!. The designs are completely different animals. EFHW don't require a ground to push against, unlike a quarter wave. The pole is fibreglass and the antenna is vertical to work portable over salt water. I have no plans to use verticals at home as they are crap in a domestic environment. I'm sure you now see you jumped the gun. this is a friendly hobby, let's keep it that way

[@BrianMorrison]

Those capacitors are to resonate the transformer secondary so that it presents a high impedance at ~14MHz to the half wave of wire forming the radiating element, the input to the transformer is tapped down so that the impedance is near 50 ohms for the bands desired. It won't be perfectly 50 ohms on the intended bands, the intention is to get a low enough VSWR that a low power Tx can still drive it or a higher power one using an antenna matching unit to get a lower VSWR to avoid the Tx power being folded back by any protection circuitry fitted.

[@mk1tina]

Thanks Brian. Thank god you can see its not a Balun. This antenna design confuses so many people .. You should see the emails I get :-/ 73

[@BrianMorrison]

I don't think many people understand how you feed a half wave or other high impedance antenna, everyone is fixated on 50 ohm feed points without thinking about why they are (or aren't) that impedance and what you have to do to get current flowing on the radiating element. Depressing about the ad hominem attacks on you by some people, it's not good, especially from people with amateur licences from way back who should know better.

[@mk1tina]

Brian Morrison thanks for your comment. You have hit the nail on the head, people just don't understand the science of triband EFHW antenna building. The video was to clarify the myths and help show how it works when multi banded. Sadly people just send me abusive emails claiming I have built this 9:1 wrong!. or made the Balun wrong or i need a ground. Sometimes I wonder how they got a licence .. You sir have restored my faith in others understanding antennas that are not the standard school of thought.. 73 and have a great Xmas. 2e0vov