End Fed Halfwave Autotransformer 49:1 Cores Tested

[@survivalcomms]

I had better results with the fair rite 2643251002 than using 240 cores when I went down this rabbit hole last year. Thanks for sharing !

[@TheSmokinApe]

Hey SC, I have a few of those sitting here as well. Just wanted to do my due diligence in the testing, thanks for watching bro 👍

[@RatchetFWD]

I agree on the 1002s

[@RatchetFWD]

Evil ???? Has videos on this

[@wb7ond]

This is good info for your viewers. I was at a hamfest this past weekend, a fellow was selling his home-made wound EFHW antennas. I casually asked if he knew the loss of the home-made transformers. He did not own a NanoVNA nor any other measuring device. He assured me that these made contacts though. I ended the conversation. I did direct him to your YT channel as well as Colin's. Your YT "handle" is easy to remember as its pretty unique! Even though there is some controversy about the two methods of measuring loss with little difference between them, You do a great service here... Thank you... Regards

[@TheSmokinApe]

Anyone selling antennas should have the ability to test them, otherwise they are just copying something and can’t verify build or material quality. Thanks for the comment 👍

[@robertmeyer4744]

nice job. I tried many 49:1 type auto transformers. Stacking the cores helps with efficiency as well as core type. I used type 61 Ferrite and 2 stack. worked great upper bands. 6 meters was ok. 10/11/12 meters was bast. 40 not so great . Other cores were tested like 52 ferrite mix. Collin did a 3 stack found that great . I am working with 4:1 now . just have a t 200-2 power iron to play with. Got great antenna at 20.5 FT 5/8 wave for 11 meters. without tuning I got 1.7 SWR . made a vertical with counterpoise. hooked a stock SSB CB to it. talked skip all over. band was open. super RX on 5/8 wave. The outher day I made a 39 Ft sloper. 5/8 wave at 20 meters. SWR was 1.9 . under 2 the whole band. With 7300 got on FT8 just phuse tune for antenna. Super contacts. Lots of south America . at at 50 watts . I checked outher bands . I can tune 10/11/12/15/17/20/40. had to e-tune on 30/60/80 . I found 4:1 works great. I used 20.5 FT / 25 FT/ 39 FT speaker wire . Now I need longer pole. And better core for 4:1 . the T 200-2 ran fine 50 watt FT8 no heating. #14 Mag wire. what I had. I just ordered a T 240 wound 4:1 but different wraps. rated 1-54 MHZ at 1.5 KW . going to try that. For 160 /80 meters 49:1 use the 3 turn primary . Better I found on lower frequencies. 56:1 and 64:1 also works ,effects the length of wire. helps with 40 meters 66ft wire. The 25FT 4:1 works like a end fed 5/8 wave. like the outher length. So is not a random wire non resonet. I modeled all 3 length . and Nano VNA sweep. It is tuning on 5/8 wave harmonics. That is 1 of many reasons the Poseidon works so well. Good job with that one. I used MMANA software for modeling. DX commander has video's on that . How I learned it. 73

[@TheSmokinApe]

As you mentioned, there are a few ways to do the 49:1. More testing to come. Thanks for watching Robert 👍

[@fastradioburst253]

You consistently have great content, Ape. Your presentations and explanations are clear, well done, and informative. I appreciate the work that you do to make these videos and experiments. I’ve learned a lot.

[@TheSmokinApe]

Awesome FRB, glad you like the videos 👍

[@cornbread-KO5RN]

YOU KNOW SMOKIN I’M GLAD YOU DO THE RESIDUAL RESEARCH ON THESE SIMPLE SUBJECT IT SAVES ME THE TIME EXPLAINING IT TO DAPPER DAN 👍

[@TheSmokinApe]

Haha, glad to be of service 👍

[@Andy-up6li]

Great video like always. Make me want to start building things again. Thanks

[@TheSmokinApe]

Glad you liked it Andy, thanks for watching 👍

[@JimAndyAllyn]

Most people wind ununs with the first two turns bifilar - two wires twisted together. That might give you a little lower losses, which clearly would be good at the lower frequencies. Also, most wind half the turns then cross over to the other side to wind the other half, but Jerry Sevick, W2FMI, says this isn't necessary below 100 MHz. Spacing the turns out to fill most of the core reduces the inter-winding capacitance and improves high frequency response. Some say the capacitor needs to be a very high voltage type, but being on the low impedance winding, the voltage isn't really that high (voltage = sqrt[P*R]), keeping in mind that operating under high SWR conditions will increase the voltage accordingly. I use 2 stacked and glued cores to make 49:1 ununs, but a single core is fine for low power - and for demonstrating the principles!

[@johnwest7993]

Tapping the windings provides ever so slightly lower loss. Twisting is just more convenient. The crossover technique just causes the wire to come out on the opposite side of the coil from the starting point, another convenience. For maximum efficiency, as opposed to convenience, one should really use an air-wound transformer with larger wire, and taps, which carried out to its logical conclusion turns the device into an antenna tuner. It's all about the degree of trade-off you are willing to make between convenience and efficiency.

[@JimAndyAllyn]

@@johnwest7993 Fourteen turns on an FT240-43 core gives you 210 microhenries inductance. To get the same inductance from an air core coil, it would take 65 turns, 4 inches in diameter, and 6 inches long. That's a pretty good sized coil, and probably larger than most people would want. I generally use air core inductors in my VHF and UHF designs, but toroids are sure convenient at lower frequencies. With that much wire, it might be interesting to see what the skin effect losses would be. I wonder about the bandwidth of such a transformer, too. You could wind it with large diameter wire or tubing, but then that would make it even larger. I think I'll stick to toroids for my 49:1 ununs and other HF transformers.

[@TheSmokinApe]

Hey Jim, that’s how I have typically done these. Just wanted to try / test something different in this video 👍

[@KK6USYHamRadioAdventures]

Thanks Ape for the video , very interesting

[@TheSmokinApe]

Thanks for watching Chuck 👍

[@Ezzell_]

Would putting less gaps or even no gaps between the turns make it better? Or a smaller diameter (OD) but taller donut ?

[@TheSmokinApe]

I think both of those would change the results, I’m planning on doing more testing in the future 👍

[@vironpayne3405]

I concur, Evil Lair and Colin have info on these torroids. I believe Evil Lair found that stack 2ea FT240-43 cores improves performance. Stack 3ea core and performance goes back down. Right now I am taking a small break from working on an antenna that uses the 2643251002 core popularized by Colin. My nanoVNA broke. The charging port pulled apart. I gave to a buddy to see if he can fix it as it a nicer one with the N-connectors that cost about $125. I'll have to by him breakfast if he gets the job done. Adjustments have been a bit less than perdictable. I'm using a 120pf capacitor on the transformer. The interaction between the capacitor and transformer are not straight foward. They tend to work in opposite ways.

[@TheSmokinApe]

Hey viron, the caps might be a whole different video 👍

[@DonzLockz]

How much power would saturate that 16 guage?

[@TheSmokinApe]

No idea

[@fotografm]

How did you convert dB insertion loss to % efficiency ?

[@TheSmokinApe]

Here is a calculator you can use www.lasercalculator.com/db-percent-converter/

[@fotografm]

@@TheSmokinApe Thanks

[@TheSmokinApe]

@@fotografm 👍

[@WECB640]

Well done Ape.

[@TheSmokinApe]

Thanks Hollywood 👍

[@mareksp9tkw908]

Shorten antenna connections to about inch as long wires will impact transformer losses. I would expect that you should get over 80% efficiency on some bands. You can also use Owen Duffy method and use 2450ohm resistor and connect output of first transfromer straigth into S21. You will get about -17dB losses from that value you need take away value of 10log(R+50/50) where R is exact measured value of used resistor. GL 73 Marek SP9TKW

[@TheSmokinApe]

Thanks Marek

[@SM3TEK-Lars]

Hi Ape. You get better efficiancy with 2 stacked 240-43 cores or if you use a Ferrit 2643251002 core. MM0OPX have done some work on the losses on diffefent core. Have done it myself just for fun. I'm build several and for me a stacked 2x240 performes better than a singel core. For time being I compare the 2 stack with the 002 core, the 002 core seems a bit better. Just for your attention Tnx for yor work 73

[@corradoQC]

I believe you get even more efficiency on most bands with a 3 stack but 10 meters becomes inefficient.

[@SM3TEK-Lars]

​@@corradoQCyes but I think U need the 51 if you do a 3 stack. 10 meter is useless on a efhw any way, the radiatoin pattern on 10 is no good. I use a singel vertikal for 12-10 meter

[@TheSmokinApe]

Thanks for the info Lasse 👍

[@ChrisRobinsonKF6NFW]

i HAVENT TRIED READING THE COMMENTS. However, Have you tried different winding patterns to see different results. As well, have you tried winding for more mono band or even if multi-band, maybe being more refined to a couple of bands instead of all of them. In my experience the different winding patterns certainly make a difference on the results you get. You can cluster the windings on one side and favor the lower end or higher end of the bands, or spread them out and favor all of the bands, there are many trick you can do to find the desired outcome. However there will always be a sacrifice somewhere. This is only one of the many reasons I do not like EFHW as multi band antennas.

[@watersstanton]

The losses do seem excessive. Maybe possible to apply power to input and measure output when terminated with 2450 resistor?Also maybe do a VSWR run with this setup? I think it is worth trying to prove the figures beyond any doubt. Great subject!

[@TheSmokinApe]

Hey Walter, I’m planning to continue testing these cores with various windings. Thanks for watching 👍

[@patthesoundguy]

How did you know I needed this video right now 😉

[@TheSmokinApe]

Haha, hope it was helpful

[@patthesoundguy]

@@TheSmokinApe Yes very interesting and helpful, I want to wind toroids to save me some money, so any information on them is golden

[@TheSmokinApe]

Here’s a playlist that might help: Learn about Chokes, Baluns and UnUns for Ham Radio Antennas kzbin.info/aero/PLm8ROkpFeqoqkGQtBYfcT9Y-2GCKxBuuk

[@patthesoundguy]

@@TheSmokinApe that's awesome! Thanks brother! I learned a lot when I took the ham course but doing some of it in practice is another. I need to get to winding my own and get good at it.

[@TheSmokinApe]

Building your own antennas is pretty rewarding 👍

[@MikeN2MAK]

Maybe see if them cores would make a better choke? I just got the tester from Halibut recently and need to play with it.

[@TheSmokinApe]

That tester is pretty sweet 👍

[@johndenby6192]

Two or even three windings to fill the perimeter of the core, all connected in parallel would improve bandwidth

[@gregwmanning]

Excellent video thanks Ape, What do you think maybe the reason for below expected results? What I would really appreciate, if you do exactly the same testing setup but wind the toroid's as a real transformers or baluns with two turns on primary and separate winding with fourteen turns on the secondary with the cap across the primary winding (I guess). I've always wondered why an autotransformer is always used not a balun, maybe because the following antenna does not require a counterpoise? Thanks again Greg VK7GM

[@johnwest7993]

An autotransformer is more efficient than a transformer with primary/secondary isolation. A transformer with an isolated secondary is only used when isolation is required for a specific application, and antenna impedance matching isn't one of them. The reason for a lower than 'hoped for' efficiency (I use those words because these are toroid cores of an unknown material,) is because whatever the composition of these toroids (the Mix of the cores) is not suitable for this application, in particular on the lower frequencies. It isn't even known if these are powdered iron or ferrite composition cores, ferrite being the material of choice for most broadband impedance transformation applications such as this all-band HF impedance matcher, with powdered iron mixes most useful for single band, tuned circuits, and oscillator sorts of applications. Then the specific Mix, size, and shape of each is selected for the frequency range and power handling requirements of the application. There are a lot of variables in proper magnetics selection, from price to packaging, but mostly in commercial applications. As hobbyists who are only purchasing a few cores, and where price and packaging aren't of great importance one can more easily pick a suitable core for their needs. For instance, powdered iron Mix 2 (red and gray) for lower HF tuned circuits and powdered iron Mix 6 (yellow and gray) for higher frequency HF tuned circuits is fine. Then you just pick the size core to be large enough to handle the general power requirement, QRP, 100 W, or KW. As for broadband applications, use ferrite cores, types/Mixes 31 for lower HF range efficiency, (specifically 160 meters,) and 43 for higher HF bands are generally good selections. (I hope I remembered that one right about Mix 31 and Mix 43 ferrite. You might want to check it.) If you want to maximize efficiency then there are some taller, somewhat narrower diameter toroids that will increase efficiency several percent. Just some rules of thumb to minimize how much money you need to put into a toroid collection in order to have them handy for ham shack projects. As you get into VHF/UHF you can use air-core coils and core materials no longer much matter, though in some high G or high vibrational applications such as in machinery or in off-road vehicles or handheld radios you may need to use cores for mechanical strength, then the dielectrics of the forms, the core materials, becomes the item of concern.

[@TheSmokinApe]

They are ferrite.

[@TheSmokinApe]

Hey Greg, I have a bunch of Mix 43 on order for further comparison videos 👍

[@Andy-up6li]

I have used the 240-43 to make my end fed antennas but never have had good results on 10 meter. 40 and 20 are great but on the rest of the harmonics no go for me. I live in a city with no land so I guess I can't ask for to much.

[@TheSmokinApe]

It can be hard to get 10m on them, personally I like a dipole for 10 👍

[@MrStanwyck]

Great video Ape…. I hope you find a more efficient solution and let us know. Have a great Labor Day weekend….

[@TheSmokinApe]

More testing videos to come, thanks for watching 👍

[@PauloNeuenschwander]

Hey... Very interesting video! But the question now is how to improve the results? Are you thinking in doing a video about that? I hope so! And looking forward for that!! Thanks for sharing man!

[@TheSmokinApe]

Hey Snoopy, I am going to do a comparison against multiple windings 👍

[@PauloNeuenschwander]

Looking forward to seeing the results.

[@TheSmokinApe]

@@PauloNeuenschwander I ordered a bunch of cores, should be here in about a week or so

[@macgyver5108]

Did you try looking up your order history to see what mix type you bought?

[@TheSmokinApe]

Yeah, I got through a lot of toe-roids so it’s hard to say which batch these were with certainty. I’m fairly confident they are mix 43

[@macgyver5108]

@@TheSmokinApe test them to some known 43's? As MANY as you've tested you probably could see where they start to fall off on your VNA compared to your old video results. 😎🤓

[@TheSmokinApe]

I just got some 43s so that’s the plan 👍

[@germanjohn5626]

The winding should be spread over most of the core is you want to use it for transmit.

[@TheSmokinApe]

That’s what I typically do but the bunched up windings is all the range these days. I wanted to roll one up to test it out 👍

[@ChrisRobinsonKF6NFW]

Explain this theory. I havent heard this one before.

[@germanjohn5626]

@@ChrisRobinsonKF6NFW May I point you to an excellent resource that will answer all questions you might have about torroidial transformers. Title Transmission line transformers by Jerry Sevik W2FMI.

[@fm71450]

Dear Ape, as always - time well spent watching your videos. Takeaway for me? If I BUY a component, like a balun or unun, I will ask for test info to be an informed consumer. Before I start making my first balun or unun, I will be much further along in my experience and learning. Thank you for this “leg up” in my HAM journey. Best, KQ4IXD

[@TheSmokinApe]

Hey FM, glad to hear the videos are helpful. Thanks for watching 👍

[@JimAndyAllyn]

TKD? You mean TDK?

[@TheSmokinApe]

D’oh!

[@pnowikow]

As a new amateur who's just learning this stuff, should i but an efhh kit from someone who has done the math? I think i know my answer.

[@TheSmokinApe]

Kits are a great way to get started.

[@pnowikow]

@@TheSmokinApe thanks Ape

[@TheSmokinApe]

You bet

[@RoyBarbosa-rh3oo]

Colin (MM0OPX) has been testing core efficiency on EFHW and presented some very interesting results. He uses a 43 mix "much beefier" 2643251002 core, 14 turns auto transformer (tap) configuration. In this video (kzbin.info/www/bejne/boSrp4J7bcmJadk) he shares a spreadsheet with the results. I've built one for my self, didn't test the efficiency, but was a bit disappointed with the SWR with a 2450 ohm dummy load. In a previous video you demonstrated much better results with a "traditional" core. I am curious if you can, not only replicate MM0OPX results, but perhaps you could include the SWR dummy load test?

[@TheSmokinApe]

Yeah, Colin did a good job with those. I’ll do more testing in the future 👍

[@ChrisRobinsonKF6NFW]

There is a huge and good reason for this. I was part of a group that did experiments with this earlier this year. Dave- W0LEV did a write up of the findings .Most arent understanding of a few things with their baluns/transformers. First the moment you leave the fundamental frequency you will always have a problem, even more so if you leave the band. The balun becomes wildly unpredictable with the task of transforming and matching when we leave the designed band. The EFHW is NOT a multiband antenna. it is a monoband dipole. PERIOD. You are not asking your 40 meter dipole to work everything with satisfactory results, why are you asking that of the EF? Colin-M0OPX has done some great work. He has missed a couple things, but that isnt important, he has done great work overall, and has mostly gotten it right. he isnt explaining a few things that need to be, and this thread isnt big enough to explain it. That doesnt matter, he is explaining to the masses, not to the finite few who crave an indepth physics lesson on the hysteresis or curie effects of the Balun under full loads under extended periods. However, if he were, many more may understand a little bit better how to design their baluns for the bands they desire. I will go find the links if anyone is interested. Otherwise, the information is truly out there for those willing to dig into it. Most KZbinrs are getting it wrong though. and I do mean most. You really need to dig into more specialized vids to find some answers, and books. There are a couple folks still out here that are authors of the books that we read, they do know, and are trying to help. There are also a few folks that arent authors that are on the right path. Overall though, it is sheep being lead by sheep and wolves of misinformation. I am not saying Ape is giving wrong information, He is not. however many others are, and that is so sad that some on here are repeating the misinformation

[@TheSmokinApe]

@@ChrisRobinsonKF6NFW sure, post the links

[@KO4VNX]

I've gotten better efficiency winding wider, crossing the toroid half-way through the windings.

[@TheSmokinApe]

I tend to prefer that myself 👍

[@PhilON4VP]

It's kind a dissapointment to see these numbers. I expected the 49:1 to be a bit better performer. 73 Phil ON4VP

[@TheSmokinApe]

Right there with you Phil, was hoping for something better 👍

[@Siskiyous6]

Bored. You must not have children 😂

[@TheSmokinApe]

Lol

[@ChrisRobinsonKF6NFW]

I have 6 he can barrow for a month if he is shy of any! Ill keep one just to have around the house for some noise!

[@TheSmokinApe]

@@ChrisRobinsonKF6NFW lol

[@DonzLockz]

I wanna see baby apes with Apes wit. Lol