Best Ferrite Core For a 100w End Fed Half Wave Antenna
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- Опубліковано 22 сер 2024
- This video covers the core I consider to be the best choice for your 100w (any mode) End Fed Half Wave antenna across the entire HF spectrum.
Link to the spreadsheet of my EFHW transformer efficiency comparisons -
docs.google.co...
Link to core on Digikey -
www.digikey.co...
Link to the core on Mouser -
www.mouser.co....
Link to the myantennas transformer using this core -
myantennas.com...
Link to Adam K6ARK's antenna kit on Amazon -
www.amazon.com... - Наука та технологія
I made a close wound 56:1 no crossover with a TDK 100pf. Really good results except for 10mtrs where I got 80% efficiency. I tried a couple of attempts on the windings to get the efficiency nearer to yours but that’s the best I could do.
At 80% I can live with that.
I was expecting to replicate nearer to yours and I have studied your videos in detail.
Anyway had good fun experimenting.
Everybody (including myself) just keeps copying the same old design somebody came up with ages ago and then keeps adding a generous amount of hamlore.
Thank you very much for going through the effort and doing some real life experiments and collecting actual data. 👍
Exactly, its a no brainer to me to make the change.
Enjoying the videos Colin.
I have built a few based on 3x240-52, 3x240-43 and singles too.
Now I am looking at / thinking about building a high power version based on the 2643251002.....unless you have or are in the process of building one 🙂
all the best
Paul
GM0EDJ
Thanks Colin, my next project!! I was about to make with the usual 240 and a 140 but im ordering the other core now. Great video and information!
Good stuff Paul, this trumps both. Its diameter is much the same as a 140.
I have two EFHW antennas cut for 40m. One has the typical ft-240-43 core and the other has the Fair-Rite 1002 core, which by the way, I was inspired to build based on your earlier shoot-out on cores. Just this morning, I tuned to 7.039.3 to see if I could hear the Russian "K" navigation beacon. It was just readable on 1002 core and missing altogether on the 240 core. I do not know how to quantify the difference except to say that the gain in efficiency is very human-noticeable. Thank you for all your great videos and the hard work that goes into them.
Thats really great information, thanks for sharing. Antenna comparisons are very difficult to do and thats why so many get away with all the marketing BS. What your saying makes sense and would only be noticable on marginal signals but on modes like CW and FT8 it makes all the difference working the station or not. Your findings just backs up the efficiency increase we see on the bench.
The key reason that the recommended core offers improvement, is the height of the core. The wire that does the heavy lifting is the wire that is inside the toroid. The wire that runs along the top and bottom faces tends to add stray reactances. If you accept that explanation at face value, you can see why the FT240-43 isn't a great choice for transformer building.
If you stack two FT140-43 cores, you get a big improvement in efficiency.
Fair-rite developed the -52 material specifically for RF transformers in the 80-10m range. Steve Ellington built a transformer from a stack of three FT240-52 cores and that was independently verified by Owen Duffy, VK1OD at around 98% efficiency. The Curie point of -52 is much higher than -43 so it can run very hot and a lot of power.
Going back to my point about it being the wire inside the core doing the heavy lifting - most modern PAs use binocular core arrangements and should be the optimum choice, rather than sticking with toroids.
The design process for say 49:1 transformer is pretty simple. Wind the primary with just sufficient turns at the lowest operating frequency to achieve an impedance of 150-200 ohms. If that happens to be 2 turns, then we clearly need 14 turns for a 49:1.
I'm not super technically minded but worked out its to do with the core geometry and its dimensions in proportion to another. I'm building a 3x240-52 transformer which I have measured over 90% efficient via back to back.
Colin, you're way better at making videos than I am. I've been brainstorming some further efficiency items. Was thinking of doing a PCB similar to what you are doing, but have the transformer leads soldered into through holes in the board, an SMD capacitor, through holes for direct solder connection of coax to the board and the coax just exits the transformer box with a strain relief, no connector. Use a coax length 4 meters plus however much needed to get ferrite for common mode choking on the other end of it. That way it eliminates any excess lead length at the transformer and capacitor, eliminates the coax connectors at the transformer and one end of the choke. Surely that has to be worth something.
Not sure about that. You have a fantastic idea and it would make the build so much easier. I will look at this sometime if you dont mind? I've never designed a PCB with a circuit before.
You're more likely to get it done than me I think. It takes a bit to learn the software. I found EasyEDA software to be simpler and by using it a little I learned enough to start using KiCad which I would rather use since it is open source software and well suited to publishing things on sites like github. If I can ever find the time I keep meaning to make a 40/20/15/10m EFHW with that 61 mix core for portable ops. Maybe use LMR-195UF coax to keep it lightweight and just put about a 10 meter length onto the transformer box and then 2 meters away have a few ferrite beads slipped over that coax, a zip tie on each end to keep them in position and cover that with shrink tubing. Surely that is enough coax length for anything I might do portable and it eliminates every connection except at the radio. I've never tested that core with an actual antenna yet but it sure is low loss on the VNA.
Actually that 61 mix core would be good at 60m probably, but down at 80m it is more loss than I would want. I've done an EFHW in the past where I put the first harmonic right on 30m, then used a capacitor in the middle to move the fundamental up to the center of 60m, to compliment an 80-10 antenna. Maybe can use a small inductor 3.5m or so out from the transformer to move a harmonic to 17m band, something I want to try. If another harmonic were to hit 12m at the same time, fantastic compliment to a 40-10 antenna then.
One more stupid idea:
Maybe the common mode choke can be integrated with such a PCB? Chunky transformer on top, common mode choke on bottom, built with nice silver plated copper wire and good quality capacitor(s) - maybe switchable 50, 100, 150pF - in an oblong case. 🤩
So many ideas, not enough spare time. 😕
I hope my "winding gusto" comes back in a month or two.
73 guys and keep up the good work!
@@labcat73 I like the switchable caps; common mode choke on the PCB not so much.
The ease of deployment is one of the most attractive feature of the EFHW. So I run mine without counterpoise, depending on the ~30ft of coax shield instead to do that instead. So the common mode choke goes on the transceiver end. Works well.
Interesting you mention Myantennas at the end - I have the exact same model that you reference and it looks as good as what you have put together! I have his other larger one as well for high power usage and they are excellent products!! Excellent video with great evidence of your measurements!!
Thanks, yes credit where credit is due and Danny from myantennas makes great kit backed up with data, something rarely shown.
Excellent work Colin. I have the 100w K6ARK kit that I still have to build, but I like your build in a box for a more long term solution. Now to source all those parts 😁 Happy New Year.
Go for it!
Happy New Year Colin! Another great video, I've already made two transformers using that toroid a 49:1 well tested and a 56:1 that's going up in the next few days. No rush for returning the 240's. I'd far rather you hang on to them a while longer and get as much data as possible. I'm looking forward to more info on stacking with a view to maximising efficiency of high power EFHW's in the future! 73, Tom
Happy new year Tom, you're patience is appreciated. I still need to check a 2 stack. My hunch is for QRO is you will need 2 separate transformers. I dont think any one will provide efficienct broadband coverage. Time will tell though. All the best 👍
I want to try 400W with 2 or 3 of these stacked.
You can but you will lose efficiency on the higher bands unfortunately. Above 20m will be killed efficiency wise.
Thanks for information. How did your swr end up with 56:1? ( 15 turns )?
On 40m its about 1.5 to 1. Other bands its lower.
Colin, thanks for an interesting video. I’m experimenting with the same core. Following the advice of Owen Duffy I’ve built a 14:2 transformer. However instead of using the twisted wire technique I just tapped the 14 turn primary at 2 turns. Using a non inductive load of 2500 ohms my nanovna shows an SWR of less than 1.5:1 from 3 - 27 MHz. I don’t use the cross over wind but closely wind the transformer on one side of the toroid. I’ve never been sure that the “traditional” transformer design is optimum. I’m also planning to make one with a binocular core but that’s another story
I also wind my EFHW transformer like a "autotransformer" with the ground at one end, tap a few turns in, then the remainder of the turns to provide the higher impedance aerial wire attachment point. It has always puzzled me why most prefer to do it as shown in this video. Mine work very well.
I am also starting to wonder why I've been using #43 material cores when the ARRL handbook and other sources indicate that it's good for HF chokes but not for HF transformers. The inverse is true for #67 mix so I ordered some cores made from that and intend on experimenting. Perhaps the core will have less loss and generate less heat? Maybe someone knows the answer to this already. ?
I’m definitely going to try that core!!! Thanks so much for sharing your findings!
Your welcome.
Hey thanks for showing your build. I'm just starting out and i'm a visual guy so it really helped to see it all.
I am SO building this!!! Thanks for bringing it to us...
No problem 😊
Wow! You have certainly done your homework. A good antenna is perhaps the best investment you can make. Its a two-way amplifier for TX & RCV.
A few years back I started using EFHW and long-wire random endfed antennas. The EFHW is my goto antenna as a portable operator.
View Steve Ellington's video I found out how to get maximum performance out of my Ultimax 80m-10m EFHW. He tried six different configurations of choking, grounding, and counterpoise wires measuring RF current on the antenna. Installed as an inverted-L with the 49:1 transformer near the ground he found just over +dBr improvement by choking and grounding at the feedpoint.
A properly installed well made EFHW is probably within -1dBr to -dBr of a tuned dipole, and its much easier to deploy.
My Ultimax is big and bulky, so I am looking for a different antenna for man portable with my FT-857D. Currently, I am using the Cha Emcom III portable. Its fine for 20m and up, but it lacks efficiency on 80m and 40m. 80m & 40m are my primary interest for NVIS regional Emcom.
Thank you for your wonderful work!
ua-cam.com/video/MzfQybYMlUc/v-deo.html
Excellent info with very good presentation. Thank You Sir. Much Appreciated......
Because of my QTH limitations, I'm limited to Mag Loops and EFHW antennas. Luckily, I'm on the first floor and have a very large yard just outside my side door.
I'm simultaneously working on a W6NBC 4' Loop tuned via a Stepper Motor with Remote WIFI Tuning, fashioned after N6JJ's controller.
And now, because of this video, a new 56:1 UnUn (Fair-Rite Toride #26432511002) for my 63' EFHW. I'll be adding the 80M Extension Coil in the near future for late nite NVIS.
The EFHW will go up 10M via a SpiderBeam Fiberglass Pole and then slope down to a 10' PVC Pole. I should get some DX with it and reasonable NVIS from So-NH.
I expect the Loops will give me reasonable good DX all around the compass via an Armstrong Rotator. HiHi.
BTW: I'll construct a second Loop for high efficiency on 10M to get into FM Repeaters and also the upper WARC bands.
Now, if I only had some Weazle Grease to lub my areal wire for better RFing. Oh Well......
73 You-Allz.....
Your very welcome. I only do this to help others. I need to get an 80m extension coil going myself.
This is just the video I needed to watch.
I would be interested in seeing a video of how you made the measurements.
And just like magic ua-cam.com/video/TZjY2Jim7fY/v-deo.html
Great information! - I was looking for a part number for this core and was having trouble coming up with it. Thanks for all of your hard work and for sharing your test results. I Ordered a couple of cores today for testing... Can't wait to get them!
Let us know how it goes 👍
This was interesting hope you come up with more videos of ferrite testing and find out what is the best End Fed Half Wave Antenna
There is no single "best" core. This is undoubtedly the best for 100w. When you go higher in power then you lose the broadband coverage with bands above 20m suffering.
Finally got around to making a 49:1 with the 2643251002 this morning. Compared to the dual FT240s in the Balun Designs commercial unit, the impedance transformation (on 20 meters) was almost identical. I was floored when everything came up without a hitch. Running 200w SSB and I don't see the SWR rising at all, but its ~20F outside right now.
Thanks for the feedback. Myantennas rates this at 250w SSB so you should be good. I'm sure the cold helps though.
Hey Colin. In the video you mentioned the box, saying it was an "RP044 something", but couldn't remember the exact make/model. Any chance you could confirm it for us? Thanks!
Sorry, its a RP1065. All the major suppliers like mouser stock it. I can get it locally in the UK without issue.
Love this video, thanks for doing your homework and advancing the art...
Glad you enjoy it!
Great video as always Colin. Happy New Year. Daryl - VK3AWA
Happy new year!
I built an efhw with 52 core 2:14 wrap. With 67' of wire. Ive gotten it to great swr on 10, 15 and 20 but like you said i cant seem to get my swr on 40 under 2.0. Any thoughts? Try an extra wrap maybe. Also i will be building a new one in the future using your recommendations
I admit I should scan through your vids before asking but... What's the big hang up on halfwave endfeds? "Random" length endfeds are so much more versatile. You're not tied to harmonics of the fundamental frequency of the halfwave AND the impedance swings from band to band are not as severe meaning a 9:1 unun is the typical ratio of the transformer. Depending on the length chosen, the random length EF allows all band operations often with minimal tuner requirements. It strikes me that most hams don't know the difference between an EFHW and a random length endfed, assuming they're the same thing, which they are not.
I learned about endfeds quite by accident when an older Elmer tossed a 53 foot wire into tree and worked from Pennsylvania to Norway with 5 watts then repeating the stunt several times on different bands with the same antenna. Since then, the random length endfed has become my favorite portable go to antenna. (Random lengths have to be picked from a list that tells you how to avoid a harmonic of any ham band. So yes, this antenna can't/shouldn't be resonant on any ham band, which is why the impedance curves are so accommodating.)
So if you haven't done the same core material analysis using a random length, please do so.
Use whatever works for you. As uou say a random wire is anything but! Its a specific length. Losses on a 9:1 transformer are definitely less but its diminishing gains. With your 9:1 you need a tuner, an external one at that at times. Thats a compromise many dont want to make. So this transformer is about 90% efficient, your 9:1 will be about 95%. Your SWR however will he higher and probably losing 20%. I dont think there is much between the 2. As I said first, go with what works for you.
Good video. Been using my homebrew 2x ft240-43 14/2 for just over two years now and about to build another with 3 cores, and always assumed around 88-92% efficiency as mentioned in the GNARC presentation (happens to be a local club to me too). Just got a 600w amp so might even do 4 cores. Just remember 1 ft-240-43 while might be good for 100w, that's 100w ssb phone, most digital modes/cw (key down) it's closer to 40w limit, which will be evident when you see your SWR start creeping up as the core heats up.
Agree on the 40w for a single FT240-43. I did the check. This core will handle 100w digital modes till the cows come home.
Also when the antenna is used in off resonance frequencies they handle even less power.
Write a book so we can have a physical copy, we will buy it ! Most videos are guessing, every bodies 'mileage' is different (as always).
Wish I had then time to.
Hi Colin, thank you very much for the great video and all the time and effort you invested in the tests. I have a question regarding the transformer you show at 9:27 in the video. The toroid doesn't seem to be winded with the wire in a crossover configuration. Also, I tried to count the winds and it looks like it's a 14/2, rather than a 15/2 but I might be wrong. Would you still recommend 15/2 with crossover? Thank you 73s
Its definitely a 15/2. I wanted the antenna wire connection where it is so didnt do a cross over. There is no measurable difference between crossover and no crossover. Make it to suit your application.
Owen Duffy of Australia first suggested that fat ferrite core as a big efficiency improvement over the traditional toroid shapes. Check his blog for verification.
It's a shame he does not receive acknowledgment for this breakthrough in compact EFHW antennas.
Yes exactly. I dont pretend to claim any credit. I found this core via Evil Lair Electronics on YT.
Owen Duffy explains on his blog why the fatter core achieves so much better efficiency on the lower bands. An interesting read but quite technical. He knows his stuff.
I published use of this ferrite more than a year before Owen, sorry.
Thanks again, I wouldn't have known about this core without your video.
Perhaps.
Could you give me the reference number of that box that appears in the 9:23 minute ?
By the way, thank you very much for your excellent job 👍
Its an RP1065. Look that number up, thanks
@@MM0OPXFieldRadio GRS.
73
Very well presented as always, thanks!
Thanks Callum 👍
Very interesting. I have used a 240-31 core in the past
Forgot to ask this before, but what wire are you winding around this core? Just looking for gauge or diameter. Thanks, and as usual, YOU SIR, ARE A MAD GENIUS!!!
This was either 1.12 or 1.16mm
Just found your excellent channel and have subscribed. Two questions for the completed transformer, 1/ what benefits, if any, does earthing the antenna side bottom leg? 2/ could the primary and secondary windings be separated (isolated from each other) and then the secondary antenna side, bottom leg earthed?
There's no noticeable difference with either I wouldn't waste my time, both have been tried.
Did you do the crossover on the 15:2? You say it and have it in the Google doc but the antenna you’re showing seems to not have the crossover (at least thinking about the geometry of the wrapping and where the wire ends). I’m building this next weekend. Thanks for sharing! Enjoy your videos!
I've done it with and without and there is no measurable difference. Do what suits your install.
Hi Colin . I'm just a little confused as to what you now recomend to winding. 56:1 with crossover or 56:1 without crossover close wound. On the 002 cores. Have built with crossover and it's great.
All the best Kevin.
So both work and little difference between loses. Make it so it suits your application.
Colin, thanks for the interesting video. Don't you think that tuning an EFHW antenna with an L-Match tuner has less loss than with a ring transformer?
Yes but its going to be very much diminishing loses gains. With this just add 1/2 wavelength of wire for your chosen band. With an L match its only for a given frequency. I have 2 videos on the channel for a 17m and 10m 5/8 verticals with L matches which work very well.
Loved the video but what core would you use for a 100W random wire antenna? What about for a QRP random wire antenna?
Thanks. I have thought about this. I will look at it sometime. Random isnt random remember. Its a very specific length.
Good job ! Proper bit of bench testing :)
Thanks! 👍
I'm planning a 64:1 24/3 turn. The 240-43 core simply lets me use thicker wire.
But after watching this, maybe I'll stack 2 cores for power handling.
Yep, give it a go 👍
Great video Thanks for your time. What capacitor you recommend?
I use a 3kv TDK for all my efhw transformers. 500v would be more than sufficient though.
Thanks for sharing your experiences with us. Quick question, what gauge of wire did you use in your transformer?.73 de K2WC
This was 1.16mm wire.
Hi Colin. Thanks again for your time and effort to test these possibilities! Question: i just ordered 17 ga / 1.2 mm wire and two 2643251002 cores. I was considering winding the two cores stacked using the 1.2 mm wire at 56:1 ratio for more power and less loss. Thoughts?
You will get a higher power handing but you will get way more losses above 40m. The efficiency gains you can make are negligable.
@@MM0OPXFieldRadio OK. Understood. Many thanks!
Hi Colin, I was considering using my spare 2643251002 core to construct a CMC using the extra 17 ga wire left over from my 1:56 transformer project. Any idea how that might work, number of turns, power handling, and frequency range? If you haven’t looked at this yet no worries, just thought I’d ask.
Good job Colin. I've been using/selling ununs using type 43 for years. Mostly 240/140-43 and even beads. People like them, just bare bones, no enclosure. I promote the ability to vary the turns count for better tuning on given bands. Recently i have discovered that types 52 and even 61 toroids are giving me better numbers, VSWR and impedance, even as on bands low as 40 meters. This is with a 40 meter EFHW. Are my numbers an illusion as too performance? Example - ft140-61 using 2:12 ratio giving almost a perfect match on 40. Am I just making the transmitter happy? thanks and 73, John kg6zbn
Hi John, Thanks for your comments. Simple answer is yes to all your questions. The match is only half the story. You really need to do a back to back insertion loss measurement to see how much power you are losing. The 240-43 and 140-43 are very forgiving match wise. Not terrible loss wise but you can do better.
Colin, Sorry if I missed it. What was the product info for the enclosure and the mounting board please
The enclosure is an RP 1065, just google that. The mounting board I designed and had made by JLPCB.
Colin, what do you mean closed or wide spaced winding? Is the actual wound unun show later in the video close or wide wound/
Close spaced is where the wire touching. Wide spaced is where the wire is spread out around the core.
Excellent presentation, Colin! I'll be building one soon. Hopefully it will give acceptable results on 6m as well. I'll update with my results
73 de NM9X
I would be interested to see how it does on 6m 👍
In order to run more than 100 watts or so, wfhat would happen with a 56:1 dual stack using the 1002 toroid cores? Would the efficency drop off at the higher frequencies?
I have a very limited antenna system here due to the HOA Nazis, so I'd like to run my amplifier in SSB at around 350-500 watts. KB0TJ
Yes you can stack them. Personally I haven't done this but Evil Lair has and told me its not too bad. I really need to check losses. With the power your talking about may be possible.
I am a little bit confused. In the video you show a 56:1 with no crossover. In the spreadsheet it says to use 56:1 with crossover for best performance. So should we use or not use a crossover. Thank you for all the time you spend for testing this and have a good 2023 for you and your family.
Good spot, I did both and there was no measurable difference. I just didnt log it. Make your own choice depending on your installation.
@@MM0OPXFieldRadio Thank you for your answer. Will try to make one. I have now one from HF Kits and made it also with 15 turns and crossover. Is the loss you have only during TX or also on RX? And what do we notice in real world? I think I should make one to see :)
@@rademaartje1 generally I dont think you will notice the difference in the real world vs a 240-43 but being able to run a constant 100w digi is a big plus.
Colin, thanks for an interesting video. What is the name of the enclosure?
I tried the stack of Three 240-52 in a 2-14 with crossover and not very pleased. I chose to stack 3 because of running 1kw or better.
What would you recommend for high power? A stack of three 240-43?, wound 2-14 with or without cross-over?
Love to hear some commends on this.
There is no magic bullet I'm afraid. Ive found no 2 or 3 core stack any good above 20m. I've a video to make on this soon.
really nice video on the subject I have ordered some to test it out, I think I will try an inverted v, but how are the swr measurements on your antenna?, thanks for your great effort in the field 73 OZ9MSD
SWR is good. 40m is the worst. 1.8 as an an Inv L or 1.5 as an inverted V. I dont stress about SWR anymore. 2:1 or less and I'm happy.
@@MM0OPXFieldRadio Thanks for the reply, I really appreciate your work 👍
Where can i find how to wind by close winding method? Tried searching youtube, but could find a traditional method only. Please help
Just keep every turn close together. Thats all it is 👍
@MM0OPXAmateurRadio But there is a point where it needs to be soldered, and I can't figure that out. I am a new ham and a detailed video of this type of winding method will be unique on UA-cam and helps a lot to hams like me.
@@jayharwards104 its identical to a "normal" EFHW but the turns are close together. I'm unable to attach a picture here.
@MM0OPXAmateurRadio So, I'll use the same twisted wires at the beginning, same capacitor, same number of turns, right? The difference would be - no crossing to the opposite side, right?
@@jayharwards104 exactly 💯
Not like you have too many combinations to test in a lifetime… but have you considered close spaced of 1:56 and 1:64 with and without 100pF? Thank you for your metrics gathering. It is not enough to have a theory or hunch… the measurements must back it up or lead to more learning. 73
Yes exactly. I think I will wait till the warmer spring weather and where its a bit more pleasant to carry out these tests.
Hello there, like your presentation and like to use your material. I'm in Canada and try to get the material. What is the capacitor you used? tried to follow your words but struggle. Could you enter the part number into the description please ? Would be brilliant if the datasheet (PDF) could be linked too, as mouser here has apparently not the same part number for the ferrite core neither. Would really like to get the right one... Thank you ever so much, Bernd VA2VFF (Very Fine Fellow - or French Fries lol)
I will add the capacitor p/n in the description soon. The 1002 core on mouser is correct. The picture description is wrong. Look at the data sheet and note the dimensions. If i had a penny for how often it gets questioned.
thank you
Perhaps a Personal Question.. (How Long is it ?) 😉 Your Wire Length to clarify.. (in Meters or Feet) No Matter, I go Both Ways. (An Efficient Transformer Such as this) needs it's Matching EFHW wire length. Just as you I am Striving for Perfection.. Well.. (As close as possible.) .. (also).. Do you use a 100uH Coil as some setups do. ?? Thanks for posting this Video 👍👍73s
Both ways huh 😂. The length will vary depending on ground effect and consideration but it will be around 20.5m
@@MM0OPXFieldRadio Thanks so much for such a quick response to my question. Length of 20.5 meters ✔️ (I can achieve that length) My Backyard is Big Enough 👍 73s
If you have the wire start off a bit more just in case.
@@MM0OPXFieldRadio I will Do that (QSL) Perhaps another 2 or 4 Meters.
I would start at 22m
Nicely done video...How are you measuring efficiency? Have you done a video on that? 73 de VA3VVV
Yes, there's one on my channel detailing how to do this.
@@MM0OPXFieldRadio I couldn't find it...What's the title?
Hi Colin ... I've made the transformer with the fair rite core and either I do 14t or 15t ... all bands are very good except for 10m where the swr is much higher compared with the 240-43 core.
The tests are done in the excact same conditions with the transformer connected to my wire outside, same CP ... nothing changedcompared with my 240-43 set-up.
With the 240-43 I can use the complete bandwith on 10m easy. Not with the fair rite.
Do you have an idea how to get 10m better ? I didn't do the crossover. 100pF cap in place.
I've also posted a lot of this in the EFHW FB group ;)
I would try a larger capacitor as doesnt affect the lower frequencys as much. Try going up in 10pf steps.
@@MM0OPXFieldRadio
Hi Colin, thx for coming back and thx for your quick answer. I told you earlier that I was using the same antenne/feedline setup but I forgot to mention that the test has been done with the new core not installed in it's box ... it was just hanging for testing purposes offcourse.
The last winding was like 10cm long before i connected it to my antenna and offcourse when finishing everything in the box I had to cut all the ends to fit in everyything.
Once finished all my results were very good.
SWR is now even better on 15 and 20m. 40m is the same even 12m got better. Overal conclusion ... did some first tests ... worked Belgium -South of Chili yesterday (nearly 13.000km) with a 5/7 on 10m without the tuner because on 10m swr is nowhere higher then 1.8.
This core works for sure ...
Thx. and keep on going Colin ... you do a great job with your video's ;)
In your spreadsheet the 56:1 says wide spacing with crossover. The one you had made up looked more like a semi-tight spaced with no crossover.
Its a tighter core so hard to space out so just do it best I can.
Have you tried two cores together, if so how much power will it handle. Thanks for your post's I've bought half a dozen to build you transformer.
Regards Kevin G1UZL.
I haven't tried 2 cores as an antenna. The reason the it becomes very inefficient 20m up. The low bands will become marginally more efficient.
Does this apply to qrp power levels? Ie Does the efficiency vary with power?
Does this apply also to 9:1 ununs for long wire end fed antennas?
The core you recommend is out of stock :(
I have a G90 (max 20W) and want to build 49:1 and a 9:1 for portable as antenna use. I want 10m to work the best it can. VK6MIK.
The power level is irrelevant except when you put too much through it and it hits curie point. The smaller core I recommend is fine for 20w SSB. I haven't tried any 9:1's yet.
Good work Colin. I always wondered how much power can safely be run through an EFHW. They are a very trendy antenna at the moment. I use mine exclusively QRP but I am considering installing a commercial one at home that was gifted to me. Your research gives me great confidence that I could homebrew a transformer and get it working. The only issue is there would be 30 m of coax feeder and I suspect that may mess things up. Any thoughts?
Cheers, Fraser MM0EFI
The feeder shouldn't muck it up at all. Longer is better than none and it needs a counterpoise. If you have problems then install 1:1 choke 0.05 - 0.15 wavelengths from feedpoint on lowest band.
@@MM0OPXFieldRadio Cheers Colin. It's either the efhw or a doublet I'm going for. Still toying with it. The doublet will be trickier to feed and arrange, so I suspect it will be the end fed.
I love your results layout and testing method. I would be curious to see your results with a triple stack 52 mix 240 between the 14/2 and the 15/2. The triple 52 mix has become popular for DIYers lately (myself included)
I habe checked a 2 and 3 stack with 43 and 52 material. I need to do a couple more Then I can make up a follow up video. The spoiler is a 3 stack of FT240-52 is crap above 20m simply put.
@@MM0OPXFieldRadio It is good to know! I look forward to the video with results :). I have built a few of the triple stack 240-52 mix transformers and always struggled with the 17-10m portions.
Performance falls off a cliff above 20m, I'm not surprised. Unfortunately it looks like there is no QRO core that will cover 80 thru 10.
That is unfortunate. My Intellituner can match it and make it function but it is a shame it does not work as well as we have been told. I did see someone talk about adding another secondary turn on the triple stack to have a 15/2.... have you tried that yet? Curious what your results would be because if there is any improvement, I will probably try that with my spare transformer box that I built.
Another turn on the secondary wont do anything to make it much more efficienct. Core geometry along with material type is key for transformer efficiency. Do the tests for yourself and get your eyes opened.
Really good video and excellent results. The big question for me is will you sell me one? I have great results with the EFHW I have but I’m guessing it’s not that effective.
Afraid not, just dont have the time. Go with the MyAntennas version 👍
Thanks for your video my question is what size magnet wire did you use? I used 18ga for my transformer but it is a little hard to wind the coil I wonder if 20ga might work better? I really like these antennas I used a 240/43 and 18ga insulated stranded wire and have worked a bunch of DX and QRP at 5 watts.
This is 1.18mm so close to 18ga. 20ga wont make any noticable difference. If your running QRP it makes sense to use this core especially.
Hi Colin, do you know if it would be possible to make a high power QRO version by staking two or even three of those 1002 cores? 400 watts full duty cycle is the design goal for me.
Yes, most likely but there is a major catch. You will improve the efficiency very slightly on the low bands but efficiency 20m up will likely fall off a cliff.
@@MM0OPXFieldRadio Damn, maybe I'll just take what I can get lol. Thanks for the reply man :)
@@VK2XXL unfortunately you cant have it all
Great video. Is there another smaller core you would recommend for QRP operations? Say for around 25W SSB.
Yes the Fair-Rite - 2643625002 (16.25mm x 7.9mm x 14.3mm)
@@MM0OPXFieldRadio Thank you, I will order a few. What gauge wire did you use for these to wind around the Toroid? Also, what ratio did you use, such as 49:1 and so on. I appreciate all your help.
0.66mm diameter wire. 64:1, 2 primary, 16 secondary.
@@MM0OPXFieldRadio Thanks again for the quick response. Do you have any data showing the efficiency of the transformer for 40 to 10 meters? I really enjoyed your video comparing the efficiencies of the different size ferrite cores.
Yes its in my spreadsheet that you can find a link to in the description.
Excellent Video! It would be interesting to see the respective cores comparison in active use, with the temperature of the individual cores being displayed in real time: Once a core saturates, it's DONE and how could anyone expect any meaningful power transfer to take place? I don't know of it's correct or not, but I always think of a transformer as being the analog of a mechanical transmission, as we try and transfer power from one side to the other... 73 DE W8LV BILL
Great idea, in practice its has issues as you need a remote sensor that polls quicky so theres little delay. Keeping it in my mind
@@MM0OPXFieldRadio DMM thermocouples? Thermal camera?
@@w8lvradio yes, just more $$$ as I dont have either currently.
@@MM0OPXFieldRadio Yes, I have that problem here as well! I'm certain with time that we will get cheaper FLIR cameras with higher resolution. I remember when pulse oximeters were in excess of $300 US, now it's more like $20... All the Best! 73 DE W8LV BILL
Colin, is there a crossover on the transformer shown in the video? I tried to see by pausing and enlarging the screen but I couldn’t tell. Cheers Daryl VK3AWA
No crossover. No noticeable difference in efficiency with or without.
This core is difficult to find. They are on back order or out of stock in many places.
I know, demand has soared as the populatity of this core has increased. Hopefully the suppliers respond.
Interesting, I just picked up Adams kit. I may wind it your way and as I’ve always wound them 14/2.
I like to run as an inverted L and the 2/14 had a high SWR on 40 (2.5:1). As an inverted V it was ok. Going 2/15 fixed this for either config 👍
Built one swr ok on 40 but not good at all on the other bands above 2:1 even after adding the extra winding to 56 :1 this replaced the ft240-43 same wire that was below 1:1:5 on all bands what were you swr finding as a matter of interest
Very strange. 40m is 1.8:1 and the rest are less than 1.5:1. How did you have it configured?
@@MM0OPXFieldRadio 2 primary and 15 secondary on tried close spaced and wide spaced the wire was 65 feet and it's perfect with the 240-43
Sorry, how was your antenna wire orientated? Was it out in the open in the clear. The 240-43 is very forgiving but is more lossy.
Yes is 800 asl in the hills Nothing there between 2 trees but it not too high off the ground 6m both sides of the wire
So as a horizontal wire? Try an inverted v or an inverted L and see how you get on.
I'm a bit confused here about the results that you show with a 15/2 winding. Very food effieciency but you didn't seem to mention putting that extra winding on how your swr is now on 40M compared with the usual 14 secondary. I would like to know please.
Also on your spreadsheet it shows "with" crossover, the one you actyually showing which you can also buy commercialy doesn't seem to have that crossover .... is there a difference or doesn't it really matter how to wind it ?
73
ON1JV
Crossover or not it matters not in efficiency. You can choose what suits you. The extra turn on the secondary is what I needed to lower the SWR on 40m. It dropped the SWR from 2:1 to 1.5:1 in the inverted V config.
What do you think would happen efficiency and power handling if you wound with the 240 with the small taller inside like a ring inside a ring? Looping wires through both cores Reduced foot print but perhaps an interesting combination.
It has been done by others. It didn't improve efficiency much. It may improve power handling but they or havent tested.
I got myself some of these cores (the Fair-Rite 2643251002, from DigiKey), wound a couple of 15/2 transformers (wide, crossover), and tried to duplicate your numbers - what I got looked similar on the low bands (160/80/40), but substantially worse on the high ones - I'm scratching my head at what the difference might be. Could the wire used make a difference? I had 18AWG solid copper wire (1.02mm diameter), enameled.
For those interested, my efficiency percentages were: 1.8MHz: 91.3%, 3.5MHz: 89.3%, 7.1MHz: 88.1%, 14.2MHz: 82.9%, 21.2 MHz: 82.9%, 28.3 MHz: 68.4%(!)
Very strange. I have no idea. The wire I used is about that diameter. My results tie in with Evil Lairs anf MyAntennas.
"Iron loss" is loss of the B-H curve. I don't recall exactly, so here's my guess - loss is proportional to B^(3/2). Also inversely proportional to f^2. Copper loss is proportional to i^2. I think core loss dominates.
To reduce iron loss, Flux density must be limited, which in turn is related to magnetic field intensity. That's why increase cross section area of core (core stacking) and reduce magnetic path length (mid circumference).
Material type 43 is ferrite could be potentially replaced by a lower loss ferrite material.
I'm hoping somebody who knows better can comment.
I absolutely would love to know how to build this antenna. Is there a build video somewhere I can watch?
Afraid not. Its just a standard EFHW transformer but with I extra then on the secondary winding. You can mount the core however you want to.
@@MM0OPXFieldRadio I’m new to ham and building antennas not sure where to begin
Ok, start to research builds on UA-cam for 49:1 end fed half wave transformers. All the builds are very similar and have the same wiring.
Hi you can also get this core from ENRGTECH LTD at £7.45 each have you tryed a 4:1 made useing this core on
A 25ft virtical i forget the name of the anttena chris
Rybakov? No reason it shouldn't work.
@MM0OPX Amateur Radio hi i am using a rybakov for 17m to 10m with a 240/43 core and useing a sloper for 20/40m
Hello, do you have any particular type/size of wire you use to wrap the torrid?
I used 0.66mm diametet wire here.
@@MM0OPXFieldRadio thank you.
will these be better on 1:1 and 4:1 versions compared to 240-43
Not necessarily, in the case of the 1:1 you would need to check the common mode attenuation.
what was the winding wire size used for the tests and have you experimented with other wire sizes with the same core? i've experimented with FT140-43 and FT240-43 with 18AWG (1mm) in various winding methods (2T bifilar, 2T tapped, 14T non crossed, 14T crossed...) and find the losses above 20m to be just abysmal. 10m is useless at low power. i don't want a space heater, i want a more efficient antenna transformer :)
I've used 1.5 mm and 0.6mm for testing and I've noticed no difference. You need a different core to reduce losses above 20m. You cant have it all with either of those.
@@MM0OPXFieldRadio the losses with those cores is what got me searching and thus finding videos from Evil Lair and then you. my Mouser cart is filling up.
What a name a box?
Great video! What capacitor are you using?
Its a TDK 3kv 100pf.
Is that 15-2 without crossover? Also what wire size of wire?
Yes but if you want to wind a crossover its fine. The wire is 1.16mm diameter.
Does the efficiency scale up and down in a linear fashion for the same core type under different amounts of power? For example, at 90% efficiency if you lost 10 W at 100 watts in would you lose 1w white at 10W in ?
I cant confirm 100% but yes. Efficiency will drop once the core gets to currie point.
Thanks. I’m just trying to figure out if it is beneficial at 10 watts to buy this new core or stick with a regular 140-43
Subscribed!!!!
Thanks James 👍
Have you an idea when K6ARK kits will be available
I've no idea, sorry. Best to try and ask Adam direct.
Colin--nice project. Do you sell the pcb or can you share the gerber files?
Give me a few days and I will get a link to the gerber files in a zip file.
@@MM0OPXFieldRadio Hello, Colin. Thank you for creating these highly informative videos on EFHW antenna design and construction. Are you making the gerber file available for the transformer mounting board featured in this video?
The link to your spreadsheet no longer is a valid link. Looks as though UA-cam is corrupting it. Thanks // al
Still working fine for me. Have you tried on another device?
Please do a video of winding the 56:1 🙏
Can I use another TDK 100pf cap seems all the 3kv ones are sold out, can I use a 2kv one?
The 2Kv ones still more than ample. It goes on the low voltage side.
will the fair-rite 2643251002 work as well for an 1:1?
Yes it will although I would want to check thel common mode attenuation.
@@MM0OPXFieldRadio which one would you recommend for 1:1 applications based on your experience Colin? thanks!
The 140-43 or 240-43 are fine but the master is GM3SEK. Check out this videoua-cam.com/video/jeyWB_K0y38/v-deo.html
help please i live in a valley completley surrounded by hills will a efhw do the job ?? getting back into radio after 20 years, whats my best option ?
The EFHW is just a transformer, your situation depends on the angle that signals can leave your valley. Ideally you need to know this and make an antenna accordingly.
@@MM0OPXFieldRadio thanks for quick reply,
i have limited options, im in a bungalow, i was going to run a wire from the chimney to my cabin at the end of the garden, but i would probably only get europe i face south east isle of wight, niton, cb bands are dead here, im surrounded by hills, have picked up europe cb here from the back garden, are you on f book too ? i could send pics or a video, i have never made a wire before, dont think a silver rod would be any good lol
and my radio is still in the post haha, galaxy saturn, im old school just ssb lo to high and cb is what im after, but i doubt il get uk cb as hills are quite high but open, i am surrounded by water if that helps hills are 45deg front hill about 1.5 mile away to top, back garden hill 45deg 200m from my back fence
Do the core properties change if the core was granular and not fused into one piece?
Yep
Good morning, Collin
Where can I get that chart , please ?
Best 73 de 7X5AV.
Here you go docs.google.com/spreadsheets/d/13kImt_tkezngocXQ5tOBDkTscp5F-RFD/edit?usp=drivesdk&ouid=111484348574912642065&rtpof=true&sd=true
What gauge wire are you using? (obviously I'm a Yank, but if you give me a diameter I will figure it out ;) )
This is 1.18mm diameter. Is that 16 or 18ga?
@@MM0OPXFieldRadio 16awg is 1.29mm and 18awg 1.024mm. I'll take the over engineered value ;) 73 de w6mgv
Colin, What wire gauge or diameter are the windings please?
This is 1.18mm diameter wire.
Hi great vid where do u get the ferrite from please
Have a look in the description, both link there.
What size of enameled wire do you suggest? Thanks
1.4 to 1.6mm is ideal.
Hi what size MAGNET WIRE,
This is 0.66mm diameter wire.
@@MM0OPXFieldRadio thank you second question what was the length of wire for the antenna did you use
Will, or can, this include mention of 160m top-band please?
I havent checked loses on top band but the MyAntennas.com version that uses same core and same winding does so yes it will cover 160 and be efficient.
Can’t wait, seriously I am such a nerd 🎉😂🎉