Trash that FT140-43! EFHW xfmr geometry STILL matters!

[@MM0OPXFieldRadio]

This is the way........no truer words spoken! Fantastically explained and thanks for the mention. I have it on my to list to check out that 61 type core as I never use 80 or 160. Keep posting your research, it's really first class.

[@CharlesRichards-t2w]

Thank you very much! I just built a 2/14 autotransformer wind style, with the 2661102002 toroid for portable use on 20m. I initially used a 110pf capacitor and the best SWR I could get on 20m was around 3:1, and it was off in frequency (lower) from what it should have been based on the antenna length. Out of frustration I clipped out the capacitor to see what effect it would have, and lo and behold the SWR went down to under 1.1:1 on frequency. So I am very happy and also very grateful for the good information you put out.

[@DougFaulkner-px7mu]

There's such alot of old school practical knowledge that was once so normal in the HAM fraternity in this video - I also like your style. Mainly because as a 1960's child this stuff was pure "Unobtainium" no amount of money could buy it for you. Keep it simple - build it well, test it to the best of your skill & ability - but most of all try and continuously improve it with on air validations from your fellow HAMS - be an Elmer to the new guys so they can benefit from your methodology. Keep up the great video's & challenge folks where they need it. 73 Doug ZL4FS

[@Bobsbbq]

Love the humor 😄, and I'm testing and learning, from people like you, Colin, and Duffy.

[@vaamorais]

Greetings from the UK! Now that was fun and educational and evil all at the same time. On a serious note, I now feel comfortable to try to build my first antenna wire. Thanks for sharing.

[@evil_lair_electronics]

Vitor, really good to hear you are going to build your own! Building your own equipment is what ham radio should be all about!

[@graybeardradio7778]

Great EFHW solution -- Thanks for sharing and using actual data! IMHO, The best option with FB (and the "experts" there) is to delete your account and go do something useful with the time you get back in your life.

[@thuff3207]

Thank you for showing data on transformers. Testing is better than talking.

[@edahan]

Thanks for putting this out there, I always had a weird feeling about the ``e x p e r t s'' -- loving this. Make more videos!

[@philipwells2793]

Thank you for the video. It would be fascinating to know how you might wind a 9:1 transformer for maximum efficiency.

[@evil_lair_electronics]

I have minimally experimented with that in the past. Same concept really, build two of them the same, connect a VNA through them and look at the amount of loss across the desired frequency range. I start with what I hope is an excessive amount of turns, then retest the loss as I remove turns of wire watching the loss improve each time, eventually you'll remove enough that the loss will start going back up again, so then you get to rewind them with what was the best number of turns. You can't be afraid to waste wire!

[@Kinetic79]

Would also love to see this... have had a hard time finding loss characteristics for the standard triflar winding of the 9:1 transformer on the web. If I were the ideal person to do the testing, I would volunteer, but I'm afraid I'm not that person right at the moment :) If anybody is up for starting with the loss characteristics of the standard 9:1 triflar winding pattern, by following the general VNA testing approach suggested by evil_lair_electronics and MM0OPX, on perhaps a couple sizes of type -43 ferrite cores and a type -2 powdered iron core, that would be super interesting to see as a starting place! :-D

[@trcwm]

Nice one! Glad to see somebody backing up their claims with actual measurements. 73, de PA1DSP.

[@labcat73]

Thanks for the video! Nothing more fragile than a hams ego. 😆 I would never have the guts to say THIS IS THE BEST TRANSFORMER. The only thing I might say is: Compared to XYZ, this seems to work better for me. 3 microseconds later somebody else comes up with something else that might work even better. This is life, no need to get upset about it.... 🤷‍♂️

[@evil_lair_electronics]

I guess it insults their manhood. They want to say the have the biggest, baddest, best-est and if anyone says otherwise it somehow diminishes them. I don't get it. I'd be perfectly happy if someone came along and showed me something way better performing, then I could use it. BTW - I've watched your videos as well. I tend to agree with you on the crossover winding not really acting like a normal turn. Also thank you for your LC meter comparison, I purchased an LCR45.

[@hshpegel]

I liked you video and will give building and testing several versions a try. Thanks for the ideas and encouragement. My approach to what I view on any media is along the same line as Mae West's idea about opinions. You can look her quote up but bottom line: They are opinions, not facts. I don't discard what can't be proven, is badly stated, or is just just BS. It just get pushed into the pile that is 10 times bigger than than the "this works" pile. Sometimes there is a gem in all that garbage. Thanks again for a excellent presentation.

[@g0fvt]

With many of these devices people just rehash old data or misunderstand their own results. I have done a fair amount of work with a NanoVNA on common mode chokes, Most of the published designs are not great at all. With good but cheap test equipment there is very little reason to not do the experiments. To be honest I am not sure about the use of the capacitors on these UNUNS, an attempt to mask some of the behaviour of the actual transformer. A 1dB loss might not seem much on the other station's S-meter but at high power something is going to get hot.

[@flatlandermirrors]

Just got done building up and testing 2 transformers on my nanovna. I got on 40 0.21, 20 0.23, 15 0.365, and 10 meters at 28.575 0.715 db loss. Pretty effing good! Next is the wire…

[@Realmikeguyver]

Can you do a video on how to measure the efficiency of an EFHW? That video would be HUGE!

[@MM0OPXFieldRadio]

Here you go, thats if YT lets me share the link kzbin.info/www/bejne/iovNimWAntJqnLs

[@paulsengupta971]

Colin, MM0OPX has a video where he shows how he measured the efficiency of the transformers.

[@paulsengupta971]

Look for "How to measure Insersion Loss of an End Fed Half Wave Transformer"

[@CriticalThinker-42]

Remember the Benny Hill definition of Expert... "Ex is a Has Been, and a Spurt is a Drip Under Pressure" 😄 73 mike

[@enginedave]

It was Collin that persuaded me to trash my 140/240's. Actually i took the 140's and made 2 dual core ganella baluns which have been successful on my 40 meter loop. I use the 240's for commin mode chokes. (correct me if im wrong on that) Sometime soon ill experiment with high power and i believe Colin says the 240's are better suited for that. K0PKE

[@RonanCantwell]

Interesting video and extra marks for mentioning Colin's work. Did you wind that last transformer as a single wire with a tap or did you do the waste-of-spacebook twisty-pair thing?

[@evil_lair_electronics]

My experience has been that single wire wound with the turns as tightly together as possible and adding the tap always shows lower loss.

[@kkshell999]

@@evil_lair_electronics Yes,very nice!

[@VK2XXL]

Please don't change your presentation style! I crack up laughing every time you mention the 'e x p e r t s'! And you're doing exactly what this hobby is meant to be all about. Experiments. I'm looking forward to building my own version of this. 73 VK2XXL

[@bruceweight7319]

I agree. I spent quite a bit of money and time and nothing tested how I wanted it to. I complained and said all the scrunch up spread out this turn that turn and nothing worked. I complained that how come it was so mysterious and why shouldn't we just be able to make a certin patern and come out ok? I got hammered on the group as I said the sience was junk. But anyway. I had some mystery cores and not even sure what they are? perhaps 77 mix but three cores even though not perfect allow me to get on 80 and run 400 watts ssb on 80 and 40 20 is ok but above that not so much. I need a setup that can handle about 500 watts ssb and I havn't seen anything on those groups that will. I wonder if type K cores would work as they are made for broad band transformers. Problem is they cost 20 bucks a piece they are just under 2.4 inches and they have a curved build.

[@sv2dsy]

Thanks a lot for your nice video. Congratulations...and 73's SV2DSY

[@stevesilsby5288]

Thanks for the useful, well documented data. Well done, sir. As to the humor, disparaging remarks, etc., they don't affect what I tuned in for so I will refrain from commenting on them. 73 de WA4BRL

[@jp6364]

What length wire did you use to get the nice graph at the 16:50 mark? Great video. 👍

[@evil_lair_electronics]

About 18.5m.

[@bruceweight7319]

What I would have liked is if someone would have given a list of materials a how too video to build a best QRP a 100 watt and perhaps a 450 watt ssb transformer. A fail safe you use these materials you build it this way and shazam you have a great transformer and antenna. Mine were all over the place. Perhaps I should have focused on finding good capacitors. I notice on comercial models the capacitors are about the size of a dime and two or three times as thick. the cheap ones are thick but small diameter.

[@markhaywood7307]

Can you make a video showing the making of the last transformer please

[@evil_lair_electronics]

kzbin.info/www/bejne/ZqSUnJmur7GJjsU

[@Aimsport-video]

Excellent video again! Is your EFHW deployed with a choke, counterpoise? Approximate length and deployment? Sloper? Experimental results rule!

[@evil_lair_electronics]

The antenna which the graph in this video is from has the transformer about 14m high and it is a slope as the pole on the other end is 4m tall, but it is far enough away that an 80m antenna will fit, so this shorter antenna doesn't get anywhere near that low. Choke 2m from the transformer, no counterpoise.

[@Aimsport-video]

@@evil_lair_electronics thank you.

[@timg5tm941]

Fabulous video!

[@philwhoareyou3677]

Really like the video, only question I have is about the capacitor rating of 10Kv? I guess this is just a worst case scenario value? just working on that 1000w needs 240v peak into 50Ohms resistive, lets give that some x10 fudge factor to allow for very bad VSWR's etc still comes to 2.4Kv. Will just a 3Kv or 2Kv do? I understand to buy good quality TDK ones. Just wondering do we need the 10Kv model that's all.

[@evil_lair_electronics]

You are correct plus those no name 10kv/15kv caps are high loss, never use them. I use the 3kv TDK caps, they are low loss and inexpensive.

[@nvrumi]

I have little use for FB in general. Someone referred to it as "an exercise in abnormal psychology." I agree and quote that comment often in reference to the platform. It seems to bring out the worst in many users. I refuse to play. Enough of that. I came back to this video after rewatching MM0OPX's detailed analysis of EFHW transformer efficiency. I have an EFHW I'm going to rebuild with your recommended toroid. You didn't mention if you used a counterpoise and choked the coax at the feedpoint of the antenna or if you used the coax as the counterpoise. Would you care to comment on that? 73 de AG7TX

[@evil_lair_electronics]

I've never used a counterpoise. As well as these antennas graph on the analyzer when you get the lengths correct, I don't see any reason for one.

[@tomking8597]

Nice Job. Thanks for sharing When you made the antenna how high did you put it? And what was the finished length if you know it? I’m just curious.

[@evil_lair_electronics]

Transformer is 14m high, the wire slopes down some from there. I didn't measure the wire length, I just start out around 20m and adjust until the tuning is correct. I could move it to another location on my property and I'm sure it would want the length adjusted some again.

[@presidentspilot]

QUESTION: .....Keith, what would you say would be max power for the Fair-Rite 2661102002 toroid for the EFHW? 100 watts, perhaps: MAX? (Damn Great article!! (Darn it,.. I just ordered 3 X FT240-52's YESTERDAY, and they were shipped this morning!!) LOL!! Ron K6PAM, Carmel, Ca

[@cthoadmin7458]

I thought Steve Ellington's advice was gospel, but I now see I am perhaps mistaken. You sir, have done for the EFHW what TRX Lab did for the choke balun, actually measured! It's kind of what scientists and engineers do, measure. What value resistor did you terminate the EFHW with to do your VNA sweep? Once I know this I will rush to my NanoVNA... Is the EFHW still a worthwhile antenna above 100W, or do the losses start to mount at higher power?

[@evil_lair_electronics]

I build 2 identical transformers, connect the secondaries together. So transformation from 50 to 2450 ohms then back to 50, get the S21 measurement. Whatever loss amount is shown, divide by 2.

[@cthoadmin7458]

@@evil_lair_electronics I will try that very thing! Any advice on 9:1 Ununs Evil Lair? Some people use T200 powdered iron cores, others use T43 Ferite. If you wanted a broadband 40 and 20m "random" wire antenna...

[@evil_lair_electronics]

@@cthoadmin7458 I have only tested 9:1 one time, it was just because I needed something for reception on old German tabletop tube radios I restore, they have 450 ohm antenna via banana jacks and I wanted to be able to connect with coax. So I tested the same way I test 49:1, did it with two 5943002701 that I had, wound them in the usual trifilar way. Starting with 9 turns, I removed one turn at a time and re-measured until I reached the lowest loss value, then the next turn removal made the loss go back up. 6 turns was lowest loss, the loss amount rose slightly with frequency, best being about -0.3dB for the pair on 160 meters, the worst being a bit less than -0.6dB for the pair at the top of 10 meters. I figure it is way easier to make a low loss 9:1 if I got it less then 0.15 to 0.3 each everywhere on the first try.

[@cthoadmin7458]

@@evil_lair_electronics Thanks for the info! 73 VK4QP

[@StuartLaningham]

You and Colin have inspired me to do this type of testing with my newly acquired nano VNA. I've been trying to replicate your good results with the dual stacked 240-43 (5943003801) cores and must be missing something. I'm getting losses around 15-17 dB at 30 MHz when testing them with 100 pF TDK Caps (CC45SL3FD101JYVNACT-ND) with both the wide cross-over a tight windings. If you don't mind sharing, how did you wind the dual 240-43s and what capacitors did you use?

[@evil_lair_electronics]

Hi, dual 240-43 made a nice transformer for me. I did tightly wound and tapped after 2 turns, with a CC45 100pf cap. Losses for the pair were -1.1 to -1.3 across HF so cut that in half.

[@StuartLaningham]

@@evil_lair_electronics Thank you very much for the reply and thank you very much for the videos. Looks like I'm using the same materials and methods, so I'll retrace my steps and hopefully find my error.

[@SM3TEK-Lars]

​@@evil_lair_electronicsHello Sm3tek on this side. Come across your channel by pure luck. Have been following this e x p e r t on FB and built a couple of EFHW both for 80-10 and 40-10. Now I gone reuse my 49:1 trafos with stacked 240-43 and rewind with 1.8mm coppar wire and do your winding whitout crossover and do a Tight winding. Is it the usual winding 2 with tap and a total of 14. Have the nanovna and I will try to measure the loss. Thanks for your work on this subject. Best regards from sweden

[@clems6989]

What facebook group are you talking about?

[@evil_lair_electronics]

There is more than one. EFHW groups.

[@johnward7619]

What if you stack 2 of the conventional ones together?

[@evil_lair_electronics]

graph for stack of 2 is already shown in this video

[@johnward7619]

Will watch again, thanks

[@jj25397]

I'm late to the EFHW party, as usual. I just happen to have two 240-43 cores and seen your graph on two stacked and I would like your advice on using them for my first transformer. Could you elaborate on their construction and anything else You're willing to share? Many thanks ahead of time. 73

[@Masirah1]

Congratulations

[@survivalcomms]

Excellent !

[@jaij147]

How much power is that one ferrite rated for? If we need to push around 400 watts, would you suggest stacking multiple ferrites?

[@evil_lair_electronics]

Have you done any loss testing and found a stack that is actually efficient? The only stacks I ever tested which looked good was a 2 stack of 5943003801 for 80 - 10m or a 2 stack of 5961003801 for 40 - 10m. I really can't speak to wattage. I know I am hard on the equipment I have because I am always doing digital, but I work the world including multiple times to Antarctica on less than 50 watts. Of course focusing on efficiency helps ensure that as much of that power as possible actually gets to the antenna wire. Some of these guys running high power but with things like the crappy 3 stack of 52 mix, cheap lossy coax with poorly installed connectors, improper choking, using a tuner which does nothing to stop that high SWR still there down the entire feedline length, etc, they might actually be putting less onto the antenna wire than I do after all their losses add up.

[@jaij147]

@@evil_lair_electronics Thanks! Just starting to get into doing some of these tests on my own. Till now was building 'proven' and 'vetted' designs 🙂. Both you and Colin refer to using the two transformer method to test. Would be great if one of you could make a video on the topic. Thanks again!

[@wd8dsb]

@@evil_lair_electronics Big follower and fan of yours. Based on a formula and Flux Density guidelines from an old Amidon technical data sheet the 2661102002 should be able to handle a continuous power of 88 watts on 7 MHz as an example when using 2 turns on the primary, and 220 watts when running CW since the CW duty cycle = 40% (I have also seen this formula elsewhere). In comparison the 2643251002 core should be able to handle a continuous power of 155 watts on 7 MHz when using 2 turns on the primary, and 388 watts when running CW. I've been using the 2643251002 core based on your previous work and today I built and tested two transformers using the 2661102002 core based on your work and I'm very impressed with the results. Thanks and 73, Don (wd8dsb)

[@donaldsmith3048]

It is like talking to a Doctor. You use numbers that many do not understand. I have never thought the cross over was any good. I made my first and only EFHW using 240-43. 2 turns and 14 turns. I didn't do the cross over. I do not have all the things to test it like you have. But it tuned up good on the 4 bands 40-10. I can tune in the others with my MFJ 940. I don't have the room in my back yard for a longer wire. I am going to make a portable antenna soon. Looking at using 140-43 for that. With the same 2 turns, 14 turns. I only have 100p caps, hope that will work OK. Let me know what you think. I am just a dumb new to all this, trying to learn as I go. Thank you for the information! 73 W4DES

[@zsradioham]

Not what Steve said. Dump the 140-43 and find the better torroids.

[@RatchetFWD]

Losses and swr numbers here suggest 2T 14T and a quality 120pf cap. 2661102002 first choice if you don’t need 160 and 80m 2643102002 if you do. Gonna build one these myself and do the measurements for fun. 🎉

[@kd5inm]

I like this video

[@AB1Vampire]

Nice Graphic

[@tomgburklin1112]

dont change your style :) i like the humor ... guess that makes me a sicko ha ha ha

[@evil_lair_electronics]

I don't intend to, the Connecticut cowboy and his butt buddies are still spewing their bile in that dumpster fire of a facebook group!