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EFHW ham radio HF antenna transformer tests - build the best yourself - save money build and learn
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- čas přidán 17. 08. 2024
- Short comparison of popular EFHW Ham radio HF antenna transformers with instruction on how to build one that puts the popular ones to shame. Save your money build it yourself and increase your skills.
#survivalcomms
references you should check out :
@MM0OPXAmateurRadio
@evil_lair_electronics
Great video, Nice to see and listen to someone who knows what they’re talking about, much appreciated, after nearly 60 years, I now now where most of my losses are, (in the Ferrite cores) BTW like the use of the vice, makes it look perfect, thanks for sharing 👍😃
You are welcome ! Thank you very much and thanks for watching !
Probably the best analysis (posting references) I have seen, showing the differences in the characteristics of the two cores. His analysis echo's the results of two other posters.. I have saved this for our club.. a straight-up discussion and build with no extra fluff.. just the facts.
Thank you very much ! Thanks for watching !
Well done. Striving for efficiency and doing the testing to prove it! 👍
Thank you very much ! I did the capacitor testing too and spoiler alert your conclusions were what I observed in my testing. Video should be up today. Thanks for watching !
@@survivalcomms excellent! If you happen across any which are lower loss than TDK I would be interested in hearing about it! I did try a couple of others which were specifically marketed as high frequency and/or high Q. They didn't measure up.
@@evil_lair_electronics Will do . I tried some 15kv ones and on the thermal imager the look like little LEDs under RF.
Love the thorough explanations and analysis. Great content for us antenna newbs.
You are welcome ! Thanks for watching !
Excellent presentation! Step by step is easy to follow. A+
Thank you very much ! Thanks for watching !
I've made quite a few End fed I've not done 61 yet. this is very interesting about temperature very good video. thanks
You are welcome ! Thanks for watching !
Thanks for the mention 😀. I hadn't seen your channel before but this video came up in my suggestions. Thanks for the experiments its great to see others doing this and the results broadly mirroring whats out there. I dont have the equipment to do what have done, especially the power test. 73, Colin
You are welcome Colin. Thank you for your content and work pointing me in the right direction. Please keep up the excellent work. If you ever need any big inductors for your projects drop me a note. Thanks for watching and 73
My next EFHW is going to use this technique. Thanks.
You are welcome. Give it a try. Thanks for watching !
800grit works a charm to take the nearly microscoping sharp flashing off that toroid corners. Allows for greater tension when winding.
I did not find and sharp corners in the 8 examples I wound . Thanks for watching !
Great tip using the vise.. Good video thanks..
You are welcome ! Thanks for watching !
Excellent video, and 100% share your view that amateur radio is all about experimenting and testing. I use a 49:1 on 140-43 but I pretty much only use 40 and 30, so might try the 64:1. And I’ll definitely try the new approach too. Thanks for the great content. Best 73.
Thank you ! Give it a try it is always fun to experiment. Thanks for watching and 73
Excellent video! I also watched several of Steve Ellington's videos. He analyzes probably 8-10 store bought transformers and about 8 different ways to hookup an inverted-L (he tries other configurations) with respect to grounding, choking, and use of counterpoise wires. Tools used in analysis are a field strength meter and RF ammeter.
The conclusions are the myAntennas that uses the torroid in your video has best performance. The best configuration is an inverted-L that is choked and grounded at the transformer feedpoint with the transformer close to the ground, within about 3ft. This configuration provides about 3dB improvement over grounding and choking at the transeiver.
For the RF ammeter testing the horizonatal portion of the antenna was only about 7ft-8ft above ground.
He also experimented with chicken wire laid out below the antenna at a normal elevation about 30ft agl to improve NVIS.
Most of his videos are rambling with low production value, but the information is good to very good.
Thank you very much for sharing ! Thanks for watching !
As usual... looks like something from the Roswell landing; but would expect nothing less !! Great Vid BB !!
Ty Terry :) Hope all is well with you !
Thanks for great video! Your tests demonstrate what I've experienced. Love the EFHW. I enjoy making the transformers. But, they do have losses. Sometimes switching from an EFHW to a resonant antenna makes contacts seem like shooting fish in a barrel. Your ferrite alternative is very interesting and it takes up less space.
Thank you ! I'm thankful to the folks that paved the way for that transformer layout. There are many who have created content on it and its a shame that they don't get the play that the big ham radio marketing channels get. Here are a few give them a visit you will be glad you did.
@MM0OPXAmateurRadio
@evil_lair_electronics
@dl2man
Thanks for watching !
Excellent video!
Thank you ! Thanks for watching !
It's the size and dimensions that account for the differences. That difference however, are limited to single core use. The fat cores cannot be stacked like the 240's.
Thanks for watching !
Great video, however given all the heat is around the windings then I expect that the loss is copper loss. If it was core losses then I would expect the entire core to be just as hot as the flux goes through the entire core equally. Try doubling the copper wire size to cut your losses.
Thanks for watching !
Great video, I hope you are preparing for Idalia. Stay safe my friend.
Thank you ! I am as ready as one can be . Thank you for watching !
Excellent information! BTW. Where can I buy a couple of the Survival Comms patches?
Thank you ! I do not have patches made but I have had some awesome decals made . They are foil and look amazing. I haven't put them out there yet but stay tuned. Thanks for watching !
If I was concerned about loss I'd wind an air-core coil instead of ferrite, and I'd put multiple taps on it in any event to get the best match for the installation location and the band of interest.
Cool idea you should do it and make a video. Thanks for watching !
I have seen a number of videos suggesting the use of 52 mix instead of 43. The claim was that 43 was often used commercially due to greater availability and lower cost. I'd love to see a similar workup to compare efficiency of 52 mix across the bands vs 43.
Colin @MM0OPXAmateurRadio has done that and has the data on his channel. Thanks for watching !
Evil Lair did a test on the 61 material (the 2643251002 cable core form factor) and it worked just fine for 40m and up but NOT for 80... insufficent mu... unable to purchase 52 material as a cable core I cut a FT 240 52 donut in half with an angle saw, glued the 2 halves together and this closely approxmiates the cross-sectional mass of the smaller cable cores. Wound auto-transformer style as Brett has done this works exceptionally well on all bands.... I could detect no heating of the care @ 100 watts... As Brett mentions.. the TDK 100-120pf caps are far superior
It would be interesting to see how some of the popular commercial EFHW's xformers perform; e.g., Balun Designs, MyAntenna, etc.
The MyAntenna one does tout impressive stats however you can build 10 of these for the cost of one of those. Plus building your own stuff is what amateur radio is about. Thanks for watching !
You should've set a hot spot on the Flir, the images are just misleading if you don't know how thermal images work. And having all those transformers next to each other on the Flir at the same time would've shown how cool the last transformer runs. Else a good and informative video👍👍, 73
Thanks for watching !
In the transmitter test section where you're using the smaller thicker cores, I can plainly see that there are 2 twisted wires for the primary windings. At the end of the video you only have a single wire wrapped with 2 turns with the feedpoint on the 2nd turn from ground. I built one of these using the end of the video and attaching the feedpoint at the 2nd turn, but it seems it's missing the 2 turns for the start of the secondary. Normally the feedpoint would be on a wire that makes 2 turns to ground, then comes back over the original 2 and continues with no connection to the feed point for 12 more turns.
When I tried to use it, no matter how little power I was running, the SWR kept moving until it stops at some point. If I stopped transmitting and started again, the SWR would start high and come back down again as if it was a heat problem. I'm going to unhook the feedpoint, add a new wire with 2 turns and try again.
Did I miss something here in the construction portion of the video?
What specifically is your question ? Thanks for watching !
@@survivalcommsat the end of the video, where you're winding the transformer it doesn't appear to have a primar/secondary winding, it appears to be a tapped inductor.
I wish we could post an image here, but I'll try my best to draw it with text.
Instead of having a 2 wire primary, and 14 secondary windings like so where the 2 lines on top is the feedpoint (the left 2 would be wired together for the ground connection.
In the first one here, the "W" is 2 turns of the primary, and each "M" is 2 turns each of the secondary)
| |
W
MMMMMMMM
In this pic, the "W"'s represent 2 tuns of wire on the core.
It's wired like this where the feedpoint is tapped on the 2nd point of the winding, but the entire wire is in series.
| |
WWWWWWW
Earlier in the transmitter test section, it appears there is a second wire for the primary winding on both cores.
@@PaulReedyYes its tapped and not wound. It is slightly more efficient that way. I explain completely in detail how to build it. You should try it.
@@survivalcomms I did, that's the problem. As soon as I start transmitting, SWR starts going up and eventually settles in about 15 seconds almost like something is heating up, then once I stop, if I let it "cool down" for the same amount of time and start transmitting again, it does the same thing again. I couldn't test for overheating (was only running 10-20 watts rtty for the tuner. I couldn't mess with it being we were setting up for WFD so I put a traditional balun in place which operated as expected, and SWR was solid.
@@PaulReedy Ok so you built one device that and you suspect has a thermal problem because the SWR starts climbing and settles ? Did you use the exact same core I used in the video ? I would like to be able to study the transformer in question and see precisely how it was assembled . The transformer you used for wfd was it one you built or purchased ?
Thanks, very interesting video. Do you think there are more losses in such a transformer or in L-Match? I always use a tuner instead of a transformer because it's easier to tune and I think my version has less loss, which is important for QRP.
There are losses in any device placed inline in the feed system. You could and should do your own test and see what loss there is. It is pretty easy to do with a tuner and a el cheapo VNA . Thanks for watching !
Curious if anyone knows why everyone builds the 49:1 as an auto transformer, which couples the secondary to the coax shield. I recently did an experiment, and wound a 49:1 with separate primary and secondary windings, with a counterpoise and antenna attached to the secondary and found it to be a HUGE improvement as far as common mode on the coax and conducted noise to the antenna. It seems to dramatically improve common mode problems that plague EFHW's. It does make the counterpoise mandatory, however. I haven't been able to find any examples of anyone else trying this, and I'm curious why.
I would be interested in doing that as an experiment. My choke takes care of the common mode for me but I am open to trying it out. Thanks for sharing and thanks for watching !
Good Video, I appreciate the Hands On approach, and winding tips!
At the end you said the transformer with teflon wire doesn't perform near as well in your testing, would you tell us how much difference there was?
I watched two EL videos right before I found this one, and he seems to over-stress some small differences in loss that in the real world use cases wouldn't be noticeable on the air. The difference between the 240 and 140/43s compared to this new Fairite core are not small and have peaked my interest. Thanks, 73 mike
About .2db difference however it is possibly due to the impossibility of getting as tight a wind. Tight winds and spacing do matter . There is nothing wrong with the pursuit of a better transformer design and even splitting hairs over it. It's enhancing the radio art IMHO. Thanks for watching !
Thanks for the info! I ordered 18ga enameled magnet wire instead of using the Teflon coated wire I had.
Never anything wrong with finding a better way to do anything!
73 mike
@@CriticalThinker-42 You are welcome !
At the beginning of the video you show the three different transformers. The ones one the far left and far right are both 49-1 although they are wired differently from each other. The one on the left has the wire doubled over and twisted together for 2 turns through the core, but the one on the right is a single wire all the way with the feed point tapped off after the second turn. Do both methods perform the same, are they interchangeable? Thanks for your cool informative videos, they are great !!!!
Thank you very much. The xfmr without the cross over and tapped has an edge in performance over the twisted primary crossover variant but it is not earth shatteringly so. Tight wound transformers have an advantage in my testing. Thanks for watching !
Thanks! @@survivalcomms
Thank You Bret
Some questions
1. Do you think a 64:1 built on a 2643251002 would be even better?
2. Would there be any changes in performance if stranded wire was used to form the turns around the toroid?
You are welcome ! You could try a 64:1 or a 56:1 using the same methodology and experiment with it. Winding a couple turns extra might work great for you. I have wound EFHW transformers with stranded hook up wire and teflon insulated stranded wire. If you can keep it tight it helps the performance in my experience due to it being repeatable. With the wire spacing / tightness of wind on the toroid you could wind one that is amazing and one that is so-so and only the slightest difference is apparent with the physical package. Its easy enough to experiment with what works for you. I personally have found the ability to tension the magnet wire equally to be more repeatable. I hope this helps and thanks for watching !
Nice video. I have been playing around with ferrite cores too, mainly for RF choking but also for 49:1 ununs. I agree with the close winding over the traditional spaced out winding. I always use a twisted pair for the primary/secondary overlap. Nice to see an alternative, kudos. I think the take-a-way is the tighter winding rather than the stubby toroid. I'm not against the stubby, I have used two 240-43 stacked and glued with a drop or two of superglue. Have you considered more windings (keeping 49:1)? I cannot see why this would not be more efficient.
The stubby toroid is really the key IMHO. If you go to Colin's channel MM0OPX Amateur radio he has done the most exhaustive work on the subject and it is well worth the time. Thanks for watching !
This video inspired me to build my very first home brew antenna, thank you for your clear and specific instructions to help beginners like myself. I did have a couple questions, though. I didn’t hear it in the video but how much power could the fair-rite unun safely be able to handle? Could you double up and increase its power handling capability? Thank you again for making this video.
Thank you ! One of these will handle 100w no sweat. I did 100w constant carrier for 2 minutes solid in my testing shown here. Thanks for watching !
This video was linked to on the FB group managed by the illustrious "experts" at 17:20CDT today. Will be interesting to see whether they delete it or make their usual idiotic comments. 😆
Im waiting with bated breath
Hey! I’m in Ocoee and would love to meet up some time if you’re interested. I’ve been building EFHW antenna transformers and used those sources. Would love to compare notes :)
What is the body of rf, antenna and center connector? I thought the center connector was for the antenna element. Body of rf is ground ?
Thanks for watching !
Thanks for fascinating information on: how to. Is there any information on this transformer's real life experience? SWR with efhw?
Yes I have a video on that exact subject in my content catalog. Thanks for watching !
Thank you for this information. Was there a reason to not wind it like the other 49:1, with the crossover? I may have missed that.
It is less efficient. Thanks for watching !
@@survivalcomms Fair enough. Thank you.
@@vinniec5286 You are welcome !
Would you say that the autotransformer version is better than the version with a seperate primary winding? I would think better because less coupling with the seperate primary.
I like it better personally - I have done it both ways and with wide spacing, crossover, split narrow spacing, teflon wire, etc. and all demonstrated considerably less loss to every iteration ( and I made dozens) wound on the FT240-43. The one shown here was the best of breed. Give it a try and see what you think. Thanks for watching !
What was the test setup? What were the loads for the test setup?
It was pretty clear in the video. Thanks for watching !
@@survivalcommsduring power test they were “loaded into a dummy load”. No value given. Thanks for the “clarity”.
@@sparky2008sparky Sure thing any time.
Hello, have you tested spread version of the winding for the latest transformer? If so, how did it perform? 73 de LZ5RG
Yes I have. It exhibited more loss than a tightly wound one. I have also made a conventionally wound one with a cross over and it exhibited more loss than the version presented. The version presented here represents the best performing EFHW transformer I have ever wound personally. One of the creators mentioned in the video asserts that capacitor quality matters so the next version will feature those capacitors recommended rather than the generic ones I used here. Thanks for watching !
Good video, thank you! I actually have one of those Fair-rite cores, seeing your video I think I'll build my first end fed with it. I'll be on 10 and 6 meters (until I get my general) any advice for building a transformer with 10 meters in mind? Do you use a counterpoise with these or rely on coax shield?
Thank you ! Honestly you are MUCH better off building a resonant dipole for 10 or 6 meters or better yet a half square. If you are limited in space install it as a sloper. Even a ground plane will work better. You will have zero transformer loss and can take advantage of the benefit of higher frequencies which is smaller form factor. If you are not space limited For 10 and 6 you could build a rhombic. The advantage of an an end fed antenna is for frequencies below 20m due to expedience in employment. There is no possible way an end fed antenna will ever equate to a center fed antenna in terms of performance. Any one who tells you different is trying to sell you something you do not need. If you want use your core and build a 40m end fed using the directions in the video. Thanks for watching !
@@survivalcomms For my current antenna I built a vertical dipole and ran it up a tree. I've been able to contact Japan pretty regularly from here in California on 10 meters. I see what you mean though about the size of efhw on high HF not being as much of an advantage over better performing antennas, thats a really good point and I tend to agree. Right now I'm working on a "positive V" dipole mounted to a squid pole made with collapsible elements in the hopes of working 10 and 6 from the same antenna. Thanks for the response!
@@youtubeaccount931 Look at building a Vee Beam. There are many decent designs that will accomplish what you desire. Get an older ARRL antenna handbook at a friends of the library book sale or perhaps ebay. Lots of great info at your fingertips.
@@survivalcomms I will, thanks for the tip!
@@youtubeaccount931 Any time its how I roll .
real world use the loss on the 240/43 is so low you would not be able to tell. I make digital coms so low of detectable audio that this would not have any affect. I did some testing with these cores. I found even higher efficiency using 14awg wire which will use the entire core. But the gains are so small even compared to a 240-43 core. If you have to run that much power your antenna must be on the ground, or in it. !st off be sure you have a high quality core. And still in the real world the difference in loss of actual on the air use shows no gains on receive or transmit. A loss of .5db to maybe 1.5db no radio will be able to tell. You really want low loss use silver wire. You can lower your loss by another .005db
You really won't know if you don't try. Thanks for watching !
I did.@@survivalcomms
Should probably just turn yer TX power down a tad more then. Doesn't matter right?
What is the purpose of the fiberglass tape??
Insulation due to the bare tap. Fiberglass tape is great stuff for all kinds of projects. Thanks for watching !
@@JustMe-dv5ix Thanks for your input ! Thanks for watching !
What if you won't to run high power
Like what kind of high power are you talking about ? The only commercial one I would recommend would be the Myantennas.com MEF-330-2K Plus. Thanks for watching !
They were no wound the same way. One is using the cross over and the other didn't. I think that is the big difference. Test it without the cross over. I did my transformer without the cross over. I went about 3/4 the way around the 240:43 I get out well. I don't have a way to do the tests you are doing. I have seen some videos that shows that the cross over is not the best way to do it.
Thanks for watching !
Thank You for the information about the Toroid. I want to get some. I am thinking that the spacing of the windings and other things, I don't understand can change the way it works. I am sure that the cross over is not good! There is a rule about the distance between the core and the wire, from my classes many years ago. Something like the loss is the Square of the distance between the core and the wire. I may be off some, Study this in 1967. I am to lazy to look it up today.@@survivalcomms
@@donaldsmith3048 You are welcome ! Thanks for watching !
What? That's a crazy power loss.
Yes it is - and people pay a lot of money for that loss. The marketing is strong. The science however....... Thanks for watching !