Great job i found simular results also by putting them back to back using a VNA. Many videos telling you to twist the primary windings of 49 to 1 I found that this causes high losses in the 10 meter band. I also found it necessary to vary the turns depending on core size. Happy to see someone else verifying the work I have done. Your a better man than I, as I haven't had the time to publish anything. Great job!!! Rob A N7RBC
Thanks, but that´s pure egoism. When I do such experiments, I forget about it a year later, when I want to build another antenna, so I watch the videos so see what I already found out ;) For me it´s just a form of documentation. Why not let others benefit.... 73 Manuel; DL2MAN
Good engineering, Manuel. I will ejoy learning from your experiments. Especially valuable for me was the insertion loss and LOSSES POWER is applied, where core heating becomes a problem. I have always wondered about this.
Wow Manuel! What an eye opener! Thank you for staying the course and putting in so much work to discover and document this. Real food for thought when running QRP and impacting the effective radiated power so much by introducing a matching device like this. 73 - KF6IF
Thank you for taking the time to wind these cores and documenting the results. It looks like the differences in the physical winding between the step-up and step-down transformers may have affected the SWR numbers.
Thank you for all the work you did winding the cores and building the spread sheet. This is very useful information. I knew wideband transformers were not lossless but didn't think they would be as lossy as they are. Thanks again. Dave K2ZU
Thanks for looking into this. One thing we learn here is to avoid making assumptions without data. In the same vein we should not assume tuner loss values, they vary dramatically depending on the actual situation, configuration and settings and can be low or high. Tuners are easier to model than transformers, so we can mathematically get some data on tuners and we need to include that, as well as feedline losses in any comparisons of antenna systems. Also concentrating on a smaller frequency range we can optimize for lower losses. Trying to handle "all bands" isn't necessarily the right goal. We have better options for higher frequency bands with small antennas, there's little need to make the 80-30 meter antenna work on 20 and up. 73 de w6akb
I used my endfed for the last SOTA and found I sit in one spot all the time and get a sore body. After my hikes up its nice to jump up and swap links on my dipole and that lets me stretch out a bit during the activation. By fluke I had a FT 82 43 to make my EFHW and it seems to run quite cool. Thanks for all the good work setting that all up and sharing with us the results. vk5cz ..
Thank you! You made a great job. Your reseach asked for my question about efficience of the wide band transformers. Even at QRP power the losses are big and make a heating.
Thank you for the level of effort put into doing, documenting, and sharing this work! I have some cores on their way to my house as I type. Some are toroids and some are called “multi-aperture” cores. Have you ever thought about using something like those? I am not sure they will give higher peak efficiencies but I am hoping for wider range at higher efficiencies. I will try and reproduce your results, thank you for giving enough info to do the test. I will try to do similar tests with the multi aperture cores.
Very well done Manuel 👏. I'm now working on a workable solution for the larger core I have been testing for insertion loss. It turns out that this what my myantennas use for their 250w (100w Continuous data) version. I need to get one of those digital power meters and I can do the "under load" test.
There is an option that I have used successfully. By winding a core with a 2 or 3 or 4 turn link then use a VNA to get the parallel resistance, you can calculate efficiency. From that you can calculate heating when you know power, mode, watts, time and efficiency. I got within 1% or 2% difference on a back to back tested pair of cores and the link-test methods (best) - FT50B-43 cores, 3T autotransformer (91%). Same with a single FT140-43 (87%). Stacking cores improves their geometry and seems to being more efficiency, 3 off FT82-43 was around the 91% also.
@@richardholmes9469 Thanks for you interesting comment. Could you give me a hint, HOW to calculate that ? I have no clue how I could calculate it, andI´d like to compare your suggestion with my measurements. 73 Manuel; DL2MAN
Thanks for sharing your investigations and creating a very informative video. The measurements at 5w with a power meter and a thermal camera were a great idea. While 20% losses sound terrible, it isn't necessarily a reason to abandon the EFHW for portable use, as some would have us believe. For comparison, I regularly use a resonant linked dipole as an inverted V, with the apex around 5m. On the 40m band this has a feed point impedance of around 20 ohm, due to the low height, leading to a 1.6dB loss in my 10m of RG174, and around 30% signal loss. It works just fine but probably isn't as efficient as an EFHW! The EFHW presents a feed point near to my operating positions so I can use around 2m of RG58 coax.
Agreed in Part, 2m COax might be too short. We suggest using at least 0,05 Lambda, which would be 4m @80m, usually we use 5m of Coax. This acts as counterpoise and aditionally helps suppressing common mode currents, when lying on the ground. I measured 5m of RG316 with -0,24dB on 80m and -0,63dB on 10m.
@@dl2man I use a 0.05 lambda counterpoise on my EFHW and have a choke BalUn on my coax near the Balun to reduce common mode current. My point being that all antennas have losses, and a simple resonant linked dipole is not without losses when at a low height and fed with 50 ohm coax. The EFHW antenna can provide many advantages for portable operation. Thank you for taking the time to respond.
Excellent approach and thorough findings of results! Best overview of the UnUn operation and efficiency…Have not seen such complete testing of its parameters! Certainly good to know for QRP RF and DC supply power issues. 73 WA4ITD
I went through the snorting ferrite phase. After going through the 12 meter therapy I no longer use ferrites for anything other than a common mode choke with the coax wound through a large core(s) for 14 turns total (usually). I have used type 43 mix but I prefer type 31 mix for chokes. I have 2 EFHW antennas in use currently (40 and 20). I use coil and cap tank circuits to match them. I understand the desire to have one wire do everything with no ATU. I also understand that no matter how much I desire more money, that simply sticking up a gas station has undesirable losses. Like 15 to 20 in the slammer. When you are limited to flea power for pota/sota/marooned-on-the-ocean I do not understand why one would be happy with dumping watts into infrared. Blue watts matter too. Yes, your pota transformers are cold when you wander out and check them. That is the duty cycle and air cooling, not the efficiency. A wire with some alligator clips for keeping the length in the 3/8 or 5/8 lambda range on each band and a light weight tuner would be my choice. Now, if you are happy with your transformer then I am happy. Sayonara :)
There is no free lunch in physics ;) Everything comes at a price. So it´s all about finding the best compromise for your situation. I have recently built a linked (multiband) dipole as another option without those losses: ua-cam.com/video/Az2Q-xpuRk8/v-deo.html 73 Manuel, DL2MAN
I have spend months building your trusdx...I got a very early kit...winding the toroids, soldering the relays, all the pins, jacks, switches, making the small tweak to the back of the display...I'm slow, evidently, and I had to do lots twice when i found my mistake from the first effort. hahah. And then. And then. I had to do the software. There was nothing on my board. I had to go back to the beginning of time and the first bit of code and start from loading the bootloader, but to do that I had to figure out how to operate a strange little device called a usbasp, and load the software for that, before I could try to load the bootloader, and what about drivers, and then I had to get the firmware working, but before I could do that I had to...well...you get the idea. So you have been on my mind a lot lately. hahah. After suffering extensively, I finally got the serial number to show. Oh jump for joy! The screen has a number! then to your site and load my call/serial #, and get that to work, then back to the little orange box of misery. And more trial and error, with more error than trial. hahah. What does this have to do with EFHW antenna core types? Well, after the orange box of now JOY came to life, I have to build a portable qrp EFHW antenna. So I have just spend the last two hours watching you like the high priest of EFHW build-ology...every word...every point...every consideration has been poured into my old age brain. I am soooo much the richer for paying attention to your work. If I had learned how to pay attention like that when I was in school, I might have gotten much better grades. hahah. I have really just one goal..get your orange box of joy, working with a laptop, a portable EFHW antenna, all using power from my ebike, in a park and making one, just one, park activation (POTA) in VarAC, or PSK or THOR (my current digital crush). And then i will call the entire adventure a success, and be happy. So, sir, thank you for the guidance. In a few more months I might be done. maybe. Don, KM4UDX
Very good result of efhw baluns. I think you had better wound 3 turns reduce to 2 turns for the primary of balun. Look at the most right for the input power of 10 meter at 27 line. it is less than another band input power. the primary wound will good by increase widing turns at low frequency band. but high frequency band will bad responce. Thank you.
Very interesting. It would be really interesting to see the same test performed with 2x of the 37 cores stacked in top of each other. Many have suggested that the smaller diameter core can achieve greater efficiency (if not in saturation).
I was thinking the same thing - stacking 2 small cores. In fact, I pressed ctrl+f and searched the comments for "37" to find this comment of yours! It's hard to get ensure toroid quality where I live and intl shipping is expensive, so I ordered a bag of 10 of the ft37 cores a while ago. I have to find a way to use them!
Thanks a lot for your work! I wonder if part of the losses are caused by saturation/ clipping which could cause distortion and nasty harmonics. Someone with a spectrum analyser could perhaps find out.
Wow... that was one heck of a test. I did noticed that small toroids are not too great for the impedance transformer. Ohh by the way... I think the dipole will still resonate on the third harmonic.. I think thats how it is. So for 7MHz dipole will also resonate on 21MHz. At least that is what I know haha. 73
I've done a bit of research on the subject on and off over the last year, and it looks to me like the most efficient set-up across the HF bands is with a Fair-Rite 2643251002 core for up to 100 Watts SSB. Being a relatively large core, and with an efficiency around 90% or more they definitely won't heat up with QRP xmitters. They have a smaller internal diameter, and are taller than the typical doughnut shape you are using in this video. That apparently improves the efficiency. They are about $8 US each, but for the efficiency and power handling capacity I think they're worth it. I plan on getting a couple of them to try out and do my own efficiency tests. The only place I found that had stock here in the USA was Mouser. The Mouser part #: 623-2643251002
Yeah, I´ve heard about it so I stock-piled a lot of different fair-rites for more testing. Before I believe stuff, I try to re-produce the test results. Video coming soon about it. But I don´t know exactly when, as I am out of available free time at this moment.
...biggest problem with the small cores is there just isn't enough 'meat' on em to do the job properly, they'll saturate pretty quick even at qrp 5 watts... the Fair Rite 2643251002 wound linear (no crossover) and 14:2 is a small form factor, suitable for portable, yet presents more core material mass than even a 2 stack FT 240 43... YOu can go from QRP to moderate QRO with just one core... and the efficiency can be over 90% ... I have 2 of em
I see lots of design for higher power that use stacks of toroids or toroids in parallel/series, and I wonder how that might change things a bit. Like, would a stack of 3 37-43s behave more like an 82-43? Or just lose even more energy to heat? Given how much more expensive the larger ones are, it might be worth investigating stacks of smaller ones... Plus, the smaller ones are easier to fit in a box, throw in a backpack and not worry about it breaking in the field.
Maybe I´ll revisit this at some point. But right now, unfortunately I don´t have the free time for it. But I agree, this would be an interesting topic. 73 Manuel; DL2MAN
I sometimes go portable and use UNUNs with FT240-43 toroids to handle 100W SSB or 30W FT8. Do you think the FT114-43 toroids will be able to handle this power level ?
Great information thank you very much Manuel. Your help saves a lot of experimental time for others who want to build similar antennas. I have a few questions: When you spoke of FT140-42, you really meant FT140-52 no ? I real question is that right at 7:50 you spoke of an " FT140-52, 2 turns primary, 14 turns secondary, it works ALL over the bands". Did I hear correct ? I am about to try out this, 52 core type, with 2 turns primary and 14 turns secondary, with a larger core , x2 FT240 size toroids. I will really appreciate your advice in this. I will be buying the toroids, probably from Fairrite shop in the Netherlands. I will also buy some FT240-43 and try them out as well. Thanks, Vincent, 9H5LX
@Vincent Borg No actually I was talking about (at least meaning) FT140-43 and FT240-43, but make sure to buy the original Amidon/Micrometals. There are also "B04A" available, which were causing trouble in our experiments. And yes 2-14 for bigger cores. More info on my Page: dl2man.de/antennas/ 73 Manuel; DL2MAN
Excellent video. Thanks a lot. Can u just comment is on 80m 2:14 ft140-43 better due to turns # or core size? Actually my point is: I'll use 2 : 82-43 for 40 up and looking for 80 or 80-40 73, kuba sp5nzf
Yes, specifically on 80m, I´d recommand using the FT140-43 with 2T Primary / 14T Secondary for up to 100W CW/SSB. Best performance on 80m in regards of SWR and losses. When you want to build smaller, you can use FT114-43 with 3T/21T for up to 25W CW/SSB. 73 Manuel; DL2MAN
@@dl2man thanks a lot. I have 5-20w ssb/cw -my shiny new great little (tr)usdx and g90. So it is only about efficiency and swr. U said that 140-43 2:14 was more efficient than 114-43 3:21 so I wander should I use 140 2:14 or 114 2:14 or 140 3:21 or 114 2:14 for best perf on 80 ... ;) 73 Kuba sp5nzf
@@jakubrusiecki1640 Don´t use 114 core with 2:14 and don´t use 140 core with 3:21. It´s either FT114-43 with 3:21 or FT140-43 with 2:14. Both are equally efficient, while 114 is smaller, lighter and can handle less Power.
Great video! Lots of useful info. I want to wind a nice 1:49 with FT114-43 core for use with IC-705 and PA500. That means I may be doing digital modes at 30 watts. What wire gauge is appropriate? Thank you.
Eindrucksvolle Arbeit. Danke dafür, dass du die Erkenntnisse teilst. K6ARK wickelt seine portable endfet anders. Wenn ich das richtig in Erinnerung habe passt er die paar und sechzig Windungen an. Kannst du vielleicht den Hintergrund des anderen Vorgehens erklären? Ich frage mich wie es sich die Dämpfung verhällt wenn man primär oder sekundär schrittweise Windungen erhöht oder erniedrigt... sicher transformiert man dann anders und der Strahler müsste verändert werden. Bekommt man so vielleicht eine Single Band efhw??
Servus, Meiner Meinung nach (ungetestet -nur aus dem Bauch heraus) sollte die kopplung zwischen primär und sekundär windung im Falle K6ARK loser sein, und damit noch niedrigere Wirkungsgrade erreichen. Nagel mich nicht fest. Ist nur so ein Bauchgefühl. Zu den aderen Fragen schlage ich mein 1. Video zu dem Thema vor. Da erkläre ich die Theorie und auch die Variationen des UnUn: ua-cam.com/video/2-4J8ECkoe4/v-deo.html 73 Manuel; DL2MAN
Thanks for doing this! Have you explored tight standard winding patterns (tapping like a standard transformer without the crossover)? I have seen general improvements by moving away from the crossover and keeping them tight. Also, take a look at Evil Lair's videos if you get a chance. He has some suggested alternative cores that seem to work better than the standard fare.
Your insertion loss figures on the spreadsheet - Did you half them for the spreadshhet or are the results we're seeing the results that the VNA displayed? I feel like you'd know this already, but the result on the VNA (two transformers) would be double what the antenna sees (single transfoirmer).
All good ! Yes it was put into account. If you want a knot in your brain, check out my later Video, where I show a different approach to test core efficiency with only one core (no back to back measurement): ua-cam.com/video/liobaos7nhs/v-deo.html 73 Manuel; DL2MAN
Thank you Manuel! This answers a question I have had for 2 years. The actual situation may be worse, nobody knows exactly the efhw antenna impedance. In a real situation, what is the actual height? Is is probably sloping, and what is the counter poise. Does the coax act as a counter poise? Any grounds? Many thanks!
@@dl2man Are you able from the heat pictures, to figure out what is heating up? is it the wires, or the core? primary or secondary? the core is governed by the amount of amps-turn. less turns on the primary will reduce the magnetic induction. I am leaning towards too many amps on the small wires. Woud bigger wires on the primary help out? A very ionteresting experiment!
Thanks for all the testing, together with videos from MM0OPX your are both helping many see that there is a lot more to understating the EFHW UnUns. 73, M0KCB
Excellent investigation. Thank you for saving me a lot of time !!! It would be interesting to try and compare one more core: the Fair-Rite 2643251002 which seems to be gaining popularity. Perhaps you have already done this. I am subscribing !
Wow! I found the heating versus loss as well. Running 500W though. Even stacking three 2.5” diameter cores (two #43s around one #42) didn’t help. If I was foolish, I’d put a fan in the box with the cores ;-) . At which point I am tempted to use a random length of wire - maybe 45m to 60m - and my trusty remoted Z-match. Even though tuners are supposed to be lossy, I have yet to see the heating/loss problems of the EFHW + unun set up in my Z-match tuners. Thanks for this very informative video, Manuel. Stay safe & healthy! 73 de W8IJN
A Z-Match is by default a symmetrical Tuner, and does not really fit an EFHW in my Opinion. I´m using a Doublet with a 200W Z-Match at home, and I can confirm, there´s amost no losses. But feeding an unsymmetrical ANtenna with it doesn´t sound right. A Z-Match, that can handle a few hundret Watts is also a unicorn, as this reuires capacitors with huge plate distances.... Or vaccum C´s..... I would like to hear more of your Setup, please. 73 Manuel; DL2MAN
@@dl2man I’m going to have to find my old photos of the first build. Or make new ones of recent changes/repairs. Meanwhile, I sent an email to your QRZ email link.
May I suggest looking at efficiency. DM2MAN is on the right track with actually testing his designs (which seems to be rare) and kudos to him. Then when you have efficiency you can calculate heating from power, mode, time etc. My suggestion FWIW is to stack 2 cores, tightly close wind as an auto transformer, 3 turn primary and total 21 or 24 turns. My tests indicate over 90% efficiency with 2 X FT240-43 and 3 turn primary. Adding a 3rd core sounds good but 3 turns may be too much for the transceiver to work into. Also, at 500W I'd be a bit nervous of the voltage on the top end of the transformer. It could get exciting (flash over). Also a 1:1 or good coax arrangement might be needed. I would definitely use radials (I run 2 of them). I did a calc. Assume 500W SSB -> ~ 100W CW. Total core weight 212 grams (2 off FT240's) and 5 minutes of transmit, 90% efficiency. Heat rise about 18C. If you run digital mode at 500W (scary thought) then it will be 5 times that rise and be at damage level unless you running antenna in the snow! VK3TXD
Sorry if i missed it in the show... why use 1kv capacitors? Why not 15kv? I am waiting on these capacitors in the mail in hopes it broadens my bandwidth.
Opposite question: Why would I use such an over-dimensioned cap, when I don´t need it ? Please look through the comments of this Video, and you´ll find, how I come up with the capacitor voltage rating suggestions. 73 Manuel; DL2MAN
All these cores and the ones I found for sale are UNMARKED. How you know the type of the material? How can I identify and validate actual core material?
That´s a very good question. The easiest way is, to buy from reliable sources (ebay/amazon/aliexpress not beeing one of them), where they have DataSheets for everything. Once recieved: Label it ! If you have an unknown core, there´s ways to measure it, but you need some equipment for that: Wind some turns on the unknown core, measure the Inductance of that coil and calculate the AL Value from that. Look up what Materials are available for that size Core and derive the Material from the measured (calculated) AL Value.
If you can get your hands on them, then measuring their resistance will weed out the duds or thise of a different composition: ua-cam.com/video/GulNhvNdIbM/v-deo.html If you cannot, I would be sure that the online seller offers a free return policy.
So would the conclusion be - feed the antenna where the impedance is as close as possible to 50Ohm to minimize transformation losses (i.e. 1/4 wave vertical or center fed dipole)? Or use as large as possible core. Another question, would it make a difference if we used 2/14 vs 3/21 in the transformer?
I have no final conclusion for you, as every Antenna is a compromise of some sort. The EFHW has Benefits: Ease of use/Setup, Multiband. Disadvantage: Loss in Broadband Transformer. Take that Endfed-Concept, and substitute the lossy broadband transformer with a resonant LC, and you have the Fuchs Antenna. Very selective, more critical componants involved (resonant circuit under Power) Lower losses, but Monoband. A Dipole is Monoband Antenna as well and needs to be fed at center Point with CMC Choke and a lot of coax because feeding point is where current flows = where it radiates, so it should be high up.... Doublet has no losses in feeding line, is multiband, but needs a (low loss) tuner. All of these Antennas work. You gotta select the advantages that you want, and check if you can live with the disadvantages. There is no free lunch in physics ;) It also depends on the available space, and where you are/want to be located in relation to the Antenna. 2:14 vs 3:21 does make a difference and depends on the core size. It´s a matter of wether XL of primary Winding is sufficient for the job. See: dl2man.de/antennas/ for more details. 73 Manuel, DL2MAN
@@dl2man Thanks Manuel, you know a man would always try to find the "ultimate" solution. I have the DX Commander Classic vertical, but if i keep it in the backyard for more than a few days the neighbours start complaining, so i have to set it up when i want to use it, then pack it back up. EFHW would be more invisible (i hope) if i use one of the trees on the property, but I am only using QRP (10W), and looking at your video i was "wow, my 10W would be cut in half". Great videos, i love watching your channel. Keep up the good work Ivan VA3NKA
I explain that in the first Video, yes: ua-cam.com/video/2-4J8ECkoe4/v-deo.html This equals 1:49 Impedance Transformation (you´ve probably heard that). 73 Manuel; DL2MAN
It’s unfortunate you gave up further testing of the 3:21 on FT140-43 because of high 10m SWR. As most EFHW transformer builders know, 10 m SWR is most affected by the value of the shunt capacitor. In fact, the cap has little to no effect on 15m and lower. I have tried a variable trimmer cap and found the optimum value for 10m SWR to often be quite different than the typical 100pf, which is just a random value to offset leakage inductance. Every different transformer will require a different value of cap. 73,
Love these videos, but one comment grabbed me, 64:1 work better for elevated feedpoints, I can't find anything on the internet about that. I am want an attic antenna, could this work? How high is elevated, and what affect does that have? Thanks, Ed KC8SBV
First of all: an attic antenna is no antenna ;) The universal directive would be: Put as much wire as possible, as high up in free air as possible. The reason, why 64:1 works better on higher elevation point, is the interaction with ground. In theory, an EFHW has infinately high impedance at feeding point. In practice it´s less. Because it´s a capacitive interaction with RF GND -which is usually earth/soil under the Antenna. Rule of thumb: The lower above GND, the lower the feeding impedance of the half wave. There are no hard boundaries. But height above Ground also affects resonant lengths, so your wire lengths need to be adjusted ! Trying to "estimate" ground level/potential on an attic seems to be an impossible task to me. 73 Manuel; DL2MAN
Is it possible that such heat is generated because of different winding? (3 primary turns instead 2 turns) What about toroids with different AL value? (AL = inductance per 1000 turns).
I suggest to look at my 1st Video to answer your questions: ua-cam.com/video/2-4J8ECkoe4/v-deo.html AN EFHW Transformer ist aways a compromise. YOu can use different Al Cores, but you will see a shift towards bad SWR on upper or lower frequencies. But maybe there´s a winding pattern, that matches those other Al Values. I simply don´t know it. I could spend weeks and months exploring those Transformers. :) 73 Manuel; DL2MAN
I did just that in this Video: ua-cam.com/video/Lq0R3Hpgmeg/v-deo.html&lc=UgzbXnOBKjTpeGAqAVd4AaABAg and core did not get warm at all. 73 Manuel; DL2MAN
Hi, Great content. I trying to figure out what is required to change when increasing the wattage from 10, 15 , 20 watt to 100 watt. This video explains it very well. Could you please provide a document with various Transformer core sizes and capacitors types/uf that can be used with different watt? May be a text/pdf document or point me to a resource that I can read. Thank you very much for the time and effort you put in Nitin
@@NitinVarmaManthena This answer is more simple: Square-Root of (Input (in Watts) *400) is your Vpp over 50 Ohms. In case of 5 Watts this equals abt 44Vpp. I want a little safety margin in case of bad SWR (min factor 2), so I recommend 100V Caps for 5W use. 100W equals 200Vpp over 50 Ohms so I recommand 500V Caps. For more or less Power, you can calculate it for yourself and apply a safety margin of at least factor 2. Use only RF Type capacitors (Minimum NP0/C0G, better Glimmer Type)
You may have already made a video comparing different mixes, ie. 43, 61, 31, 52. But if you haven't that would be interesting. I think 43 material is not the best material for 80 to 10 meter transformers. Either 31 or 61 may be better. Tests may reveal the best material for each band but testing that would be very time consuming.
I agree, that would be interesting, but I´m more "result oriented", so once I have found something that works within the desired specifications, I usually stop looking. Maybe when I´m bored ;) 73 Manuel; DL2MAN
31 Material is NOT for any EFHW unun application, it's very lossy in the HF bands making it suitable for HF common mode chokes. 61 mat is more suitable for 15m through 6m. 2 or 3 FT-240 43 and 52 mat FT-240 are best for 100w EFHW applications.
Warum kann ein Dipol nur auf einem Band betrieben werden? Das ist doch die gleiche Antenne wie eine EFHW, nur in der Mitte gespeisst. Und wenn man sich zs6bkw etc ansieht, das sind auch Multibanddipole. Beim Ringkernwickeln kommt es wohl auch darauf an, ob nur der halbe oder der ganze Kern bewickelt ist, mit der gleichen anzahl an Wicklungen und ob z.B 1:49 mit 2, 3 oder 4 Primärwindungen gewickelt wird:==> ua-cam.com/video/nZ-G4hJCTSM/v-deo.html Afaik ist der 140-43 damals vom Militär für Multiband genommen worden(die interessieren sich nicht so für effizienz), aber eigentlich im 20m Band am besten aufgehoben. Trotz allem, ein interessantes Video. Irgendwie muss man aus vielen Quellen das passende raussuchen und vergleichen (und selber testen)
Ein Dipol funktioniert deshalb nur auf einem Band, weil er am 50(60) Ohm Punkt gespeist wird. Dieser Punkt existiert nur in der Mitte von Lambda/halbe (also bei Lambda/Viertel). Bei der doppelten Frequenz ist jeder Schenkel Lambda/halbe und hochohmig. Bei der EFHW speisen wir am hochohmigen Ende und transformieren wir hochohmig, und obwohl es bei den harmonischen nicht mehr 100% passt, so reicht es dennoch für Abstrahlung und halbwegs passende Speiseimpedanz. Deshalb ist ein Endgespeister Dipol Multibandfähig, und ein Mittengespeister nicht. Es gibt aber Möglichkeiten, einen mittengespeisten Dipol Multibandfähig zu machen. Entweder mit Traps (die verlustbehaftet sind) oder mit links (Trenn-/Verbindungsstellen): ua-cam.com/video/Az2Q-xpuRk8/v-deo.html Die ZS6BKW Antenne erfordert einen Tuner, ist also ein nicht resonanter Dipol. Das nennt man im allgemeinen eigentlich vielmehr eine Doppel-Zepp. Gute Antenne, wenn man einen guten (!!!)Tuner hat. Für das Trafo-Thema muss man ein Gefühl bekommen, und viele Wege führen nach Rom. Ich habe in dem kommentierten Video versucht, die richtige Kerngröße zu finden und habe dabei noch herausgefunden, welches Wickelschema für welche Kerngröße am Besten funktioniert. dl2man.de/antennas/
You could try some type 61 and type 52 though I don't think they are supplied in as many sizes as 43. Also could you try a fair-rite 2643625002 core, you can get them thru mouser. Thank you for your efforts and sharing the results. 73/72
Do you have a suggested winding pattern and compensation capacitor for FT114-61 and -52 Jer? I tried those a while ago and the "best" I could achieve was a single band transformer for 30m band with the -61 type. So probably better efficiency, but a lot less broadband. At some point I needed a break from transformer winding and gave up ;). Edit: All my cores are FT140 variants -43, -52, -61.
Thanks for the suggestions. As I said in my closing words: "you always realize, you´ve not done enough". This topic could fill hours of Video.... 73 Manuel; DL2MAN
@@labcat73 I don't know, excellent function, low loss/high efficiency and good swr, across the entire hf range is a lot to hope for, perhaps a variable cap and some sort of swr indicator would be needed for adjustment. W7ZOI had better efficiency on 40 and 20 with a ft114-61 than with a ft114-43. K1RF says (p28) that the qrpguys "no tune endfed" setup has too little inductance on 80 and 40 using a ft114-43, modeling of it is discussed in the current july-aug '22 qex, p31, with some discussion of the fixed cap and swr. I really like what Manuel is doing, and while I am tempted to get one of the tinky K6ARK kits, I am not yet convinced it's the optimal configuration.
@@dl2man in K1RF's "The End-Fed Half-Wave Antenna" from Nov 2018, p 25, he says 3:21 with 22g wire on a fair-rite 2643625002 with a 100 pf cap is better than 90% efficient on 80 thru 10, and he says it's good for 5w digital, 12.5 cw and 20 ssb. The core is stubbier than the usual pancake like toroids used. I am tempted to try it with a k6ark pcb/bnc setup. Maybe the stubbier configuration will make a more efficient transformer.
I agree. Z-Match is a great example of a highly efficient Tuner. However: The classic N7DDC or MFC Matchboxes turn your (non resonant) Antennas into a Dummyloads with a little Radiation, as the core losses are also present in those. 73 Manuel; DL2MAN
For the lower bands an extra primary turn and the required extra secondary turns might help, but then again it might move the core closer to field saturation.
This is surprising..... it makes me wonder how you may modify your future builds on this information. Of course, I can't predict what you should do next, because your IQ is maybe three times greater than my own! So we will watch and learn from you as you modify your approach!
Try the FT50B-43. "B" version....This is a taller version of the FT50. Can be hard to find. Wind it as an auto transfomer and I get 91% efficiency. I run mine at 30W SSB. I use 2 as a 1:1 balun, or 4 for a bit more power handling that QRP. Try stacking 3 core of FT82-43. Wind 3 turn primary auto transformer. Similar efficiency. Try winding on FT140-43 as auto transformer and close wind the turns. Close winding gives best flux linking and best efficiency. Spreading out turns reduces linkage and loses efficiency. Running a separate primary and winding as bifilar has no advantage. Try the "standard" of FT240-43 as per "internet wisdom" and you will get.... no surprises from your tests here. SWR testing is interesting only, but lossy winding and builds have better SWR. Loss to SWR in short coax is far less than loss to lossy cores. WELL done on actually building and testing, a refreshing change from repeating designs that have considerable loss - and it is fun! enjoy.
As you have two transformers in series, the actual loss per transformer is HALF of the loss that you measured; that is, if you measured the power output from the high impedance output of one transformer, it should be half of your measured loss using two transformers! Thus you would be putting more signal to air than your results indicate!
I can see you're very disappointed in losing 25% of your power! (Yes, I also see that this video is a year old, so probably you've gotten over it.) But, this isn't as bad as you think. A loss of 25% is about -1.25dB. And how much is -1.25dB? On the receivers that are listening to you, it is 1/5 of an S unit. So instead of getting an S7 report, you would get an S6.8 report, but they would just round it up to S7 anyway! I know this seems ridiculous, but even loss of HALF of your power only amounts to 1/2 an S unit at the other end. Every antenna system has losses, and everything your signal goes through that doesn't have gain has loss. Have you looked at how much power you lose in your coax? I think you would be shocked. To avoid this particular loss, you could use a center-fed half-wave dipole. But there are good reasons you want to use an end-fed instead. Like you said, everything is a compromise.
All very true ! I got over it, I improved efficiency, I built center fed dipole and I´m still having fun, and that´s the main goal here. It´s just grown up Version of toys ;) Thanks for your comment ! 73 Manuel; DL2MAN
EFHW is a resonant Antenna ;) And works really well in practice. But nothing will beat a well tuned and elevated monoband DIpole. That´s for sure. 73 Manuel; DL2MAN
Great job i found simular results also by putting them back to back using a VNA.
Many videos telling you to twist the primary windings of 49 to 1 I found that this causes high losses in the 10 meter band. I also found it necessary to vary the turns depending on core size.
Happy to see someone else verifying the work I have done. Your a better man than I, as I haven't had the time to publish anything. Great job!!!
Rob A N7RBC
Thanks, but that´s pure egoism. When I do such experiments, I forget about it a year later, when I want to build another antenna, so I watch the videos so see what I already found out ;) For me it´s just a form of documentation. Why not let others benefit.... 73 Manuel; DL2MAN
Excellent research, great job. I love it when people go the whole 9 yards to answer questions like this
Thanks!
Good engineering, Manuel. I will ejoy learning from your experiments. Especially valuable for me was the insertion loss and LOSSES POWER is applied, where core heating becomes a problem. I have always wondered about this.
Wow Manuel! What an eye opener! Thank you for staying the course and putting in so much work to discover and document this. Real food for thought when running QRP and impacting the effective radiated power so much by introducing a matching device like this. 73 - KF6IF
Thank you for taking the time to wind these cores and documenting the results. It looks like the differences in the physical winding between the step-up and step-down transformers may have affected the SWR numbers.
I appreciate all the work and effort you put into your videos. Great help and resource for the hobby.
Definitely interesting video. Seeing how hot those small cores got was mind blowing.
Thank you for all the work you did winding the cores and building the spread sheet. This is very useful information. I knew wideband transformers were not lossless but didn't think they would be as lossy as they are. Thanks again. Dave K2ZU
Thanks for looking into this. One thing we learn here is to avoid making assumptions without data. In the same vein we should not assume tuner loss values, they vary dramatically depending on the actual situation, configuration and settings and can be low or high. Tuners are easier to model than transformers, so we can mathematically get some data on tuners and we need to include that, as well as feedline losses in any comparisons of antenna systems. Also concentrating on a smaller frequency range we can optimize for lower losses. Trying to handle "all bands" isn't necessarily the right goal. We have better options for higher frequency bands with small antennas, there's little need to make the 80-30 meter antenna work on 20 and up. 73 de w6akb
Great comment. Thanks !
Very nice work, was pleasantly surprised at you aproach.
Very nice to watch.
I used my endfed for the last SOTA and found I sit in one spot all the time and get a sore body. After my hikes up its nice to jump up and swap links on my dipole and that lets me stretch out a bit during the activation. By fluke I had a FT 82 43 to make my EFHW and it seems to run quite cool. Thanks for all the good work setting that all up and sharing with us the results. vk5cz ..
Absolutely fantastic!! Thank you!!
Much Love from Alaska
KL5VL ❄️
Thank you! You made a great job. Your reseach asked for my question about efficience of the wide band transformers. Even at QRP power the losses are big and make a heating.
Thank you very much for making this study of EFHW un-uns
Thank you for the level of effort put into doing, documenting, and sharing this work!
I have some cores on their way to my house as I type. Some are toroids and some are called “multi-aperture” cores. Have you ever thought about using something like those? I am not sure they will give higher peak efficiencies but I am hoping for wider range at higher efficiencies.
I will try and reproduce your results, thank you for giving enough info to do the test. I will try to do similar tests with the multi aperture cores.
Very well done Manuel 👏. I'm now working on a workable solution for the larger core I have been testing for insertion loss. It turns out that this what my myantennas use for their 250w (100w Continuous data) version. I need to get one of those digital power meters and I can do the "under load" test.
Looking forward to your Video, as this means in terms of 100W continuously at least 15W dissapation into core. 73 Manuel; DL2MAN
There is an option that I have used successfully. By winding a core with a 2 or 3 or 4 turn link then use a VNA to get the parallel resistance, you can calculate efficiency. From that you can calculate heating when you know power, mode, watts, time and efficiency. I got within 1% or 2% difference on a back to back tested pair of cores and the link-test methods (best) - FT50B-43 cores, 3T autotransformer (91%). Same with a single FT140-43 (87%). Stacking cores improves their geometry and seems to being more efficiency, 3 off FT82-43 was around the 91% also.
@@richardholmes9469 Thanks for you interesting comment. Could you give me a hint, HOW to calculate that ? I have no clue how I could calculate it, andI´d like to compare your suggestion with my measurements. 73 Manuel; DL2MAN
This is really great stuff. Thank you. You are helping me learn a lot about practical antenna implementation.
Thanks for sharing your investigations and creating a very informative video. The measurements at 5w with a power meter and a thermal camera were a great idea.
While 20% losses sound terrible, it isn't necessarily a reason to abandon the EFHW for portable use, as some would have us believe.
For comparison, I regularly use a resonant linked dipole as an inverted V, with the apex around 5m. On the 40m band this has a feed point impedance of around 20 ohm, due to the low height, leading to a 1.6dB loss in my 10m of RG174, and around 30% signal loss. It works just fine but probably isn't as efficient as an EFHW!
The EFHW presents a feed point near to my operating positions so I can use around 2m of RG58 coax.
Agreed in Part, 2m COax might be too short. We suggest using at least 0,05 Lambda, which would be 4m @80m, usually we use 5m of Coax. This acts as counterpoise and aditionally helps suppressing common mode currents, when lying on the ground. I measured 5m of RG316 with -0,24dB on 80m and -0,63dB on 10m.
@@dl2man I use a 0.05 lambda counterpoise on my EFHW and have a choke BalUn on my coax near the Balun to reduce common mode current.
My point being that all antennas have losses, and a simple resonant linked dipole is not without losses when at a low height and fed with 50 ohm coax.
The EFHW antenna can provide many advantages for portable operation.
Thank you for taking the time to respond.
Excellent approach and thorough findings of results!
Best overview of the UnUn operation and efficiency…Have not seen such complete testing of its parameters!
Certainly good to know for QRP RF and DC supply power issues.
73 WA4ITD
I went through the snorting ferrite phase. After going through the 12 meter therapy I no longer use ferrites for anything other than a common mode choke with the coax wound through a large core(s) for 14 turns total (usually). I have used type 43 mix but I prefer type 31 mix for chokes.
I have 2 EFHW antennas in use currently (40 and 20). I use coil and cap tank circuits to match them.
I understand the desire to have one wire do everything with no ATU.
I also understand that no matter how much I desire more money, that simply sticking up a gas station has undesirable losses. Like 15 to 20 in the slammer.
When you are limited to flea power for pota/sota/marooned-on-the-ocean I do not understand why one would be happy with dumping watts into infrared. Blue watts matter too.
Yes, your pota transformers are cold when you wander out and check them. That is the duty cycle and air cooling, not the efficiency.
A wire with some alligator clips for keeping the length in the 3/8 or 5/8 lambda range on each band and a light weight tuner would be my choice.
Now, if you are happy with your transformer then I am happy. Sayonara :)
There is no free lunch in physics ;) Everything comes at a price. So it´s all about finding the best compromise for your situation. I have recently built a linked (multiband) dipole as another option without those losses: ua-cam.com/video/Az2Q-xpuRk8/v-deo.html 73 Manuel, DL2MAN
I have spend months building your trusdx...I got a very early kit...winding the toroids, soldering the relays, all the pins, jacks, switches, making the small tweak to the back of the display...I'm slow, evidently, and I had to do lots twice when i found my mistake from the first effort. hahah. And then. And then. I had to do the software. There was nothing on my board. I had to go back to the beginning of time and the first bit of code and start from loading the bootloader, but to do that I had to figure out how to operate a strange little device called a usbasp, and load the software for that, before I could try to load the bootloader, and what about drivers, and then I had to get the firmware working, but before I could do that I had to...well...you get the idea. So you have been on my mind a lot lately. hahah.
After suffering extensively, I finally got the serial number to show. Oh jump for joy! The screen has a number! then to your site and load my call/serial #, and get that to work, then back to the little orange box of misery. And more trial and error, with more error than trial. hahah.
What does this have to do with EFHW antenna core types? Well, after the orange box of now JOY came to life, I have to build a portable qrp EFHW antenna. So I have just spend the last two hours watching you like the high priest of EFHW build-ology...every word...every point...every consideration has been poured into my old age brain. I am soooo much the richer for paying attention to your work. If I had learned how to pay attention like that when I was in school, I might have gotten much better grades. hahah.
I have really just one goal..get your orange box of joy, working with a laptop, a portable EFHW antenna, all using power from my ebike, in a park and making one, just one, park activation (POTA) in VarAC, or PSK or THOR (my current digital crush). And then i will call the entire adventure a success, and be happy.
So, sir, thank you for the guidance. In a few more months I might be done. maybe. Don, KM4UDX
Very good result of efhw baluns. I think you had better wound 3 turns reduce to 2 turns for the primary of balun. Look at the most right for the input power of 10 meter at 27 line. it is less than another band input power. the primary wound will good by increase widing turns at low frequency band. but high frequency band will bad responce. Thank you.
Excellent video, did you try nesting a 52 inside the 82 with the 3:21 winding?
Thanks for R&D and sharing results! "73"
Very interesting. It would be really interesting to see the same test performed with 2x of the 37 cores stacked in top of each other. Many have suggested that the smaller diameter core can achieve greater efficiency (if not in saturation).
Interesting ! Maybe I´ll re-visit.... 73 Manuel; DL2MAN
I was thinking the same thing - stacking 2 small cores. In fact, I pressed ctrl+f and searched the comments for "37" to find this comment of yours! It's hard to get ensure toroid quality where I live and intl shipping is expensive, so I ordered a bag of 10 of the ft37 cores a while ago. I have to find a way to use them!
That's a lot of building and testing. Thanks for sharing this with us, very helpful.👍🤓
Outstanding job, thank you very much for your presentation, the information was very useful.
Thanks a lot for your work! I wonder if part of the losses are caused by saturation/ clipping which could cause distortion and nasty harmonics. Someone with a spectrum analyser could perhaps find out.
Wow... that was one heck of a test. I did noticed that small toroids are not too great for the impedance transformer. Ohh by the way... I think the dipole will still resonate on the third harmonic.. I think thats how it is. So for 7MHz dipole will also resonate on 21MHz. At least that is what I know haha. 73
I've done a bit of research on the subject on and off over the last year, and it looks to me like the most efficient set-up across the HF bands is with a Fair-Rite 2643251002 core for up to 100 Watts SSB. Being a relatively large core, and with an efficiency around 90% or more they definitely won't heat up with QRP xmitters. They have a smaller internal diameter, and are taller than the typical doughnut shape you are using in this video. That apparently improves the efficiency. They are about $8 US each, but for the efficiency and power handling capacity I think they're worth it. I plan on getting a couple of them to try out and do my own efficiency tests. The only place I found that had stock here in the USA was Mouser.
The Mouser part #: 623-2643251002
Yeah, I´ve heard about it so I stock-piled a lot of different fair-rites for more testing. Before I believe stuff, I try to re-produce the test results. Video coming soon about it. But I don´t know exactly when, as I am out of available free time at this moment.
...biggest problem with the small cores is there just isn't enough 'meat' on em to do the job properly, they'll saturate pretty quick even at qrp 5 watts... the Fair Rite 2643251002 wound linear (no crossover) and 14:2 is a small form factor, suitable for portable, yet presents more core material mass than even a 2 stack FT 240 43... YOu can go from QRP to moderate QRO with just one core... and the efficiency can be over 90% ... I have 2 of em
Excellent and hard work. Could you please test the hypothesis that the antenna tuner will swallow more energy than the 1:49 transformer? 73 de KD8ZM
I see lots of design for higher power that use stacks of toroids or toroids in parallel/series, and I wonder how that might change things a bit. Like, would a stack of 3 37-43s behave more like an 82-43? Or just lose even more energy to heat?
Given how much more expensive the larger ones are, it might be worth investigating stacks of smaller ones... Plus, the smaller ones are easier to fit in a box, throw in a backpack and not worry about it breaking in the field.
Maybe I´ll revisit this at some point. But right now, unfortunately I don´t have the free time for it. But I agree, this would be an interesting topic. 73 Manuel; DL2MAN
I sometimes go portable and use UNUNs with FT240-43 toroids to handle 100W SSB or 30W FT8. Do you think the FT114-43 toroids will be able to handle this power level ?
The 114 probably not (for long) but 140s should be good to go.
Great information thank you very much Manuel. Your help saves a lot of experimental time for others who want to build similar antennas.
I have a few questions:
When you spoke of FT140-42, you really meant FT140-52 no ?
I real question is that right at 7:50 you spoke of an " FT140-52, 2 turns primary, 14 turns secondary, it works ALL over the bands".
Did I hear correct ?
I am about to try out this, 52 core type, with 2 turns primary and 14 turns secondary, with a larger core , x2 FT240 size toroids.
I will really appreciate your advice in this.
I will be buying the toroids, probably from Fairrite shop in the Netherlands.
I will also buy some FT240-43 and try them out as well.
Thanks, Vincent, 9H5LX
@Vincent Borg No actually I was talking about (at least meaning) FT140-43 and FT240-43, but make sure to buy the original Amidon/Micrometals. There are also "B04A" available, which were causing trouble in our experiments. And yes 2-14 for bigger cores. More info on my Page: dl2man.de/antennas/ 73 Manuel; DL2MAN
Excellent video. Thanks a lot. Can u just comment is on 80m 2:14 ft140-43 better due to turns # or core size?
Actually my point is: I'll use 2 : 82-43 for 40 up and looking for 80 or 80-40
73, kuba sp5nzf
Yes, specifically on 80m, I´d recommand using the FT140-43 with 2T Primary / 14T Secondary for up to 100W CW/SSB. Best performance on 80m in regards of SWR and losses. When you want to build smaller, you can use FT114-43 with 3T/21T for up to 25W CW/SSB. 73 Manuel; DL2MAN
@@dl2man thanks a lot. I have 5-20w ssb/cw -my shiny new great little (tr)usdx and g90. So it is only about efficiency and swr. U said that 140-43 2:14 was more efficient than 114-43 3:21 so I wander should I use 140 2:14 or 114 2:14 or 140 3:21 or 114 2:14 for best perf on 80 ... ;)
73 Kuba sp5nzf
@@jakubrusiecki1640 Don´t use 114 core with 2:14 and don´t use 140 core with 3:21. It´s either FT114-43 with 3:21 or FT140-43 with 2:14. Both are equally efficient, while 114 is smaller, lighter and can handle less Power.
@@dl2man thanks. My trusdx and I will be happy :)
Great video! Lots of useful info. I want to wind a nice 1:49 with FT114-43 core for use with IC-705 and PA500. That means I may be doing digital modes at 30 watts. What wire gauge is appropriate? Thank you.
You can´t go wrong with 1mm +/-
Eindrucksvolle Arbeit. Danke dafür, dass du die Erkenntnisse teilst.
K6ARK wickelt seine portable endfet anders. Wenn ich das richtig in Erinnerung habe passt er die paar und sechzig Windungen an. Kannst du vielleicht den Hintergrund des anderen Vorgehens erklären? Ich frage mich wie es sich die Dämpfung verhällt wenn man primär oder sekundär schrittweise Windungen erhöht oder erniedrigt... sicher transformiert man dann anders und der Strahler müsste verändert werden. Bekommt man so vielleicht eine Single Band efhw??
Servus, Meiner Meinung nach (ungetestet -nur aus dem Bauch heraus) sollte die kopplung zwischen primär und sekundär windung im Falle K6ARK loser sein, und damit noch niedrigere Wirkungsgrade erreichen. Nagel mich nicht fest. Ist nur so ein Bauchgefühl. Zu den aderen Fragen schlage ich mein 1. Video zu dem Thema vor. Da erkläre ich die Theorie und auch die Variationen des UnUn: ua-cam.com/video/2-4J8ECkoe4/v-deo.html 73 Manuel; DL2MAN
Thanks for doing this! Have you explored tight standard winding patterns (tapping like a standard transformer without the crossover)? I have seen general improvements by moving away from the crossover and keeping them tight. Also, take a look at Evil Lair's videos if you get a chance. He has some suggested alternative cores that seem to work better than the standard fare.
Yes, this Video is far from complete, but it was enough to answer my initial questions.
Your insertion loss figures on the spreadsheet - Did you half them for the spreadshhet or are the results we're seeing the results that the VNA displayed?
I feel like you'd know this already, but the result on the VNA (two transformers) would be double what the antenna sees (single transfoirmer).
Hold on - My bad! You wrote on the spreadsheet "single core".
What can I say, I have reading comprehension issues!
All good ! Yes it was put into account. If you want a knot in your brain, check out my later Video, where I show a different approach to test core efficiency with only one core (no back to back measurement): ua-cam.com/video/liobaos7nhs/v-deo.html 73 Manuel; DL2MAN
Thanks Manuel! Very interesting.
And yes oh boy does it take time to do these experiments. 😅
I see FT114-42 on line 9..... was this a typo? I can't find FT114-42 anywhere but want to try using that core if I can find one.
Typo: Was of course FT114-43 !
Excellent work. Best regards SP2CG
7:20 Cells A9 & A10, typo "...-42" (2 places) should be "...-43". Cheers.
Another good catch ! You´re absolutey right !
Thank you Manuel! This answers a question I have had for 2 years. The actual situation may be worse, nobody knows exactly the efhw antenna impedance. In a real situation, what is the actual height? Is is probably sloping, and what is the counter poise. Does the coax act as a counter poise? Any grounds? Many thanks!
Great questions ! And they absolutely belong to that topic. I´m going to adress them in one of the next Videos.
@@dl2man Are you able from the heat pictures, to figure out what is heating up? is it the wires, or the core? primary or secondary? the core is governed by the amount of amps-turn. less turns on the primary will reduce the magnetic induction. I am leaning towards too many amps on the small wires. Woud bigger wires on the primary help out? A very ionteresting experiment!
Thanks for all the testing, together with videos from MM0OPX your are both helping many see that there is a lot more to understating the EFHW UnUns. 73, M0KCB
Nice work and experimenting. I have learned much from your video. Keep up the hard work!
Very good video and very informative.
Very, very interesting and informative.. Thank you for taking the time to wind all those transformers, and sharing your results.. John.. G4EIJ
Can you recommend or put links to power amplifiers that I can use with your little 5 watt QRP rig? Maybe output to 20 watt or higher.
Excellent investigation. Thank you for saving me a lot of time !!! It would be interesting to try and compare one more core: the Fair-Rite 2643251002 which seems to be gaining popularity. Perhaps you have already done this. I am subscribing !
Wow! I found the heating versus loss as well. Running 500W though. Even stacking three 2.5” diameter cores (two #43s around one #42) didn’t help. If I was foolish, I’d put a fan in the box with the cores ;-) . At which point I am tempted to use a random length of wire - maybe 45m to 60m - and my trusty remoted Z-match. Even though tuners are supposed to be lossy, I have yet to see the heating/loss problems of the EFHW + unun set up in my Z-match tuners. Thanks for this very informative video, Manuel. Stay safe & healthy! 73 de W8IJN
A Z-Match is by default a symmetrical Tuner, and does not really fit an EFHW in my Opinion. I´m using a Doublet with a 200W Z-Match at home, and I can confirm, there´s amost no losses. But feeding an unsymmetrical ANtenna with it doesn´t sound right. A Z-Match, that can handle a few hundret Watts is also a unicorn, as this reuires capacitors with huge plate distances.... Or vaccum C´s..... I would like to hear more of your Setup, please. 73 Manuel; DL2MAN
@@dl2man I’m going to have to find my old photos of the first build. Or make new ones of recent changes/repairs. Meanwhile, I sent an email to your QRZ email link.
May I suggest looking at efficiency. DM2MAN is on the right track with actually testing his designs (which seems to be rare) and kudos to him. Then when you have efficiency you can calculate heating from power, mode, time etc. My suggestion FWIW is to stack 2 cores, tightly close wind as an auto transformer, 3 turn primary and total 21 or 24 turns. My tests indicate over 90% efficiency with 2 X FT240-43 and 3 turn primary. Adding a 3rd core sounds good but 3 turns may be too much for the transceiver to work into. Also, at 500W I'd be a bit nervous of the voltage on the top end of the transformer. It could get exciting (flash over). Also a 1:1 or good coax arrangement might be needed. I would definitely use radials (I run 2 of them). I did a calc. Assume 500W SSB -> ~ 100W CW. Total core weight 212 grams (2 off FT240's) and 5 minutes of transmit, 90% efficiency. Heat rise about 18C. If you run digital mode at 500W (scary thought) then it will be 5 times that rise and be at damage level unless you running antenna in the snow! VK3TXD
Sorry if i missed it in the show... why use 1kv capacitors? Why not 15kv? I am waiting on these capacitors in the mail in hopes it broadens my bandwidth.
Opposite question: Why would I use such an over-dimensioned cap, when I don´t need it ? Please look through the comments of this Video, and you´ll find, how I come up with the capacitor voltage rating suggestions. 73 Manuel; DL2MAN
All these cores and the ones I found for sale are UNMARKED.
How you know the type of the material?
How can I identify and validate actual core material?
That´s a very good question. The easiest way is, to buy from reliable sources (ebay/amazon/aliexpress not beeing one of them), where they have DataSheets for everything. Once recieved: Label it ! If you have an unknown core, there´s ways to measure it, but you need some equipment for that: Wind some turns on the unknown core, measure the Inductance of that coil and calculate the AL Value from that. Look up what Materials are available for that size Core and derive the Material from the measured (calculated) AL Value.
@@dl2man Good.
What is your (lowest cost) suggestion for measuring losses and frequency range?
@@paulcohen1555 any nanovna, that fits your Bill. They all work
If you can get your hands on them, then measuring their resistance will weed out the duds or thise of a different composition:
ua-cam.com/video/GulNhvNdIbM/v-deo.html
If you cannot, I would be sure that the online seller offers a free return policy.
So would the conclusion be - feed the antenna where the impedance is as close as possible to 50Ohm to minimize transformation losses (i.e. 1/4 wave vertical or center fed dipole)? Or use as large as possible core.
Another question, would it make a difference if we used 2/14 vs 3/21 in the transformer?
I have no final conclusion for you, as every Antenna is a compromise of some sort. The EFHW has Benefits: Ease of use/Setup, Multiband. Disadvantage: Loss in Broadband Transformer. Take that Endfed-Concept, and substitute the lossy broadband transformer with a resonant LC, and you have the Fuchs Antenna. Very selective, more critical componants involved (resonant circuit under Power) Lower losses, but Monoband. A Dipole is Monoband Antenna as well and needs to be fed at center Point with CMC Choke and a lot of coax because feeding point is where current flows = where it radiates, so it should be high up.... Doublet has no losses in feeding line, is multiband, but needs a (low loss) tuner. All of these Antennas work. You gotta select the advantages that you want, and check if you can live with the disadvantages. There is no free lunch in physics ;) It also depends on the available space, and where you are/want to be located in relation to the Antenna. 2:14 vs 3:21 does make a difference and depends on the core size. It´s a matter of wether XL of primary Winding is sufficient for the job. See: dl2man.de/antennas/ for more details. 73 Manuel, DL2MAN
@@dl2man Thanks Manuel, you know a man would always try to find the "ultimate" solution. I have the DX Commander Classic vertical, but if i keep it in the backyard for more than a few days the neighbours start complaining, so i have to set it up when i want to use it, then pack it back up.
EFHW would be more invisible (i hope) if i use one of the trees on the property, but I am only using QRP (10W), and looking at your video i was "wow, my 10W would be cut in half".
Great videos, i love watching your channel. Keep up the good work
Ivan
VA3NKA
Hey DL2MAN, the turns ratio looks like it reduces to 1:7, is that right? I've never heard of that ratio.
I explain that in the first Video, yes: ua-cam.com/video/2-4J8ECkoe4/v-deo.html This equals 1:49 Impedance Transformation (you´ve probably heard that). 73 Manuel; DL2MAN
It’s unfortunate you gave up further testing of the 3:21 on FT140-43 because of high 10m SWR. As most EFHW transformer builders know, 10 m SWR is most affected by the value of the shunt capacitor. In fact, the cap has little to no effect on 15m and lower.
I have tried a variable trimmer cap and found the optimum value for 10m SWR to often be quite different than the typical 100pf, which is just a random value to offset leakage inductance. Every different transformer will require a different value of cap. 73,
As mentioned: I´m using 2:14 for FT140-43 with great success.
@@dl2man I finally ended up using 2:14 on my FT140-43 as well, it provided a far better match across 40m - 10m than the 3:21 did.
Love these videos, but one comment grabbed me, 64:1 work better for elevated feedpoints, I can't find anything on the internet about that. I am want an attic antenna, could this work? How high is elevated, and what affect does that have? Thanks, Ed KC8SBV
First of all: an attic antenna is no antenna ;) The universal directive would be: Put as much wire as possible, as high up in free air as possible. The reason, why 64:1 works better on higher elevation point, is the interaction with ground. In theory, an EFHW has infinately high impedance at feeding point. In practice it´s less. Because it´s a capacitive interaction with RF GND -which is usually earth/soil under the Antenna. Rule of thumb: The lower above GND, the lower the feeding impedance of the half wave. There are no hard boundaries. But height above Ground also affects resonant lengths, so your wire lengths need to be adjusted ! Trying to "estimate" ground level/potential on an attic seems to be an impossible task to me. 73 Manuel; DL2MAN
Is it possible that such heat is generated because of different winding? (3 primary turns instead 2 turns) What about toroids with different AL value? (AL = inductance per 1000 turns).
I suggest to look at my 1st Video to answer your questions: ua-cam.com/video/2-4J8ECkoe4/v-deo.html AN EFHW Transformer ist aways a compromise. YOu can use different Al Cores, but you will see a shift towards bad SWR on upper or lower frequencies. But maybe there´s a winding pattern, that matches those other Al Values. I simply don´t know it. I could spend weeks and months exploring those Transformers. :) 73 Manuel; DL2MAN
Extremely interesting results. Thank you
Can use FT82-43 on 10W SSB on efhw antenna . Or need to change to FT114-43
I did just that in this Video: ua-cam.com/video/Lq0R3Hpgmeg/v-deo.html&lc=UgzbXnOBKjTpeGAqAVd4AaABAg and core did not get warm at all. 73 Manuel; DL2MAN
Hi, Great content. I trying to figure out what is required to change when increasing the wattage from 10, 15 , 20 watt to 100 watt. This video explains it very well. Could you please provide a document with various Transformer core sizes and capacitors types/uf that can be used with different watt? May be a text/pdf document or point me to a resource that I can read.
Thank you very much for the time and effort you put in
Nitin
dl2man.de/antennas/ might be just what you´re looking for. 73 Manuel; DL2MAN
@@dl2man Thank you! This is exactly what I was looking. Is there a table for capacitors too? Which type to use for a specific wattage ?
@@NitinVarmaManthena This answer is more simple: Square-Root of (Input (in Watts) *400) is your Vpp over 50 Ohms. In case of 5 Watts this equals abt 44Vpp. I want a little safety margin in case of bad SWR (min factor 2), so I recommend 100V Caps for 5W use. 100W equals 200Vpp over 50 Ohms so I recommand 500V Caps. For more or less Power, you can calculate it for yourself and apply a safety margin of at least factor 2. Use only RF Type capacitors (Minimum NP0/C0G, better Glimmer Type)
It would be very interesting to see what stacking two FT50-43 cores would do to your numbers! 😉
More loss.
Sehr interessant
You may have already made a video comparing different mixes, ie. 43, 61, 31, 52. But if you haven't that would be interesting. I think 43 material is not the best material for 80 to 10 meter transformers. Either 31 or 61 may be better. Tests may reveal the best material for each band but testing that would be very time consuming.
I agree, that would be interesting, but I´m more "result oriented", so once I have found something that works within the desired specifications, I usually stop looking. Maybe when I´m bored ;)
73 Manuel; DL2MAN
31 Material is NOT for any EFHW unun application, it's very lossy in the HF bands making it suitable for HF common mode chokes.
61 mat is more suitable for 15m through 6m.
2 or 3 FT-240 43 and 52 mat FT-240 are best for 100w EFHW applications.
@@no5x937 43 material is also lossy but the differential loss is usually pretty low. 31 material would be superior to 43 material at 1.8 mhz.
@@rickeaston3228 Yes, but very few hams use EFHW at 160m. I'll stick with 43 and 52 for 80m - 20m.
Thanks brother, very good job
Warum kann ein Dipol nur auf einem Band betrieben werden? Das ist doch die gleiche Antenne wie eine EFHW, nur in der Mitte gespeisst. Und wenn man sich zs6bkw etc ansieht, das sind auch Multibanddipole.
Beim Ringkernwickeln kommt es wohl auch darauf an, ob nur der halbe oder der ganze Kern bewickelt ist, mit der gleichen anzahl an Wicklungen und ob z.B 1:49 mit 2, 3 oder 4 Primärwindungen gewickelt wird:==> ua-cam.com/video/nZ-G4hJCTSM/v-deo.html
Afaik ist der 140-43 damals vom Militär für Multiband genommen worden(die interessieren sich nicht so für effizienz), aber eigentlich im 20m Band am besten aufgehoben.
Trotz allem, ein interessantes Video. Irgendwie muss man aus vielen Quellen das passende raussuchen und vergleichen (und selber testen)
Ein Dipol funktioniert deshalb nur auf einem Band, weil er am 50(60) Ohm Punkt gespeist wird. Dieser Punkt existiert nur in der Mitte von Lambda/halbe (also bei Lambda/Viertel). Bei der doppelten Frequenz ist jeder Schenkel Lambda/halbe und hochohmig. Bei der EFHW speisen wir am hochohmigen Ende und transformieren wir hochohmig, und obwohl es bei den harmonischen nicht mehr 100% passt, so reicht es dennoch für Abstrahlung und halbwegs passende Speiseimpedanz. Deshalb ist ein Endgespeister Dipol Multibandfähig, und ein Mittengespeister nicht. Es gibt aber Möglichkeiten, einen mittengespeisten Dipol Multibandfähig zu machen. Entweder mit Traps (die verlustbehaftet sind) oder mit links (Trenn-/Verbindungsstellen): ua-cam.com/video/Az2Q-xpuRk8/v-deo.html Die ZS6BKW Antenne erfordert einen Tuner, ist also ein nicht resonanter Dipol. Das nennt man im allgemeinen eigentlich vielmehr eine Doppel-Zepp. Gute Antenne, wenn man einen guten (!!!)Tuner hat. Für das Trafo-Thema muss man ein Gefühl bekommen, und viele Wege führen nach Rom. Ich habe in dem kommentierten Video versucht, die richtige Kerngröße zu finden und habe dabei noch herausgefunden, welches Wickelschema für welche Kerngröße am Besten funktioniert. dl2man.de/antennas/
@@dl2man Besten Dank für die Info. 73
now for my setup i am using some cheap FT60-26. really helpful video. 73 de OE8GKE
Quite interesting!
You could try some type 61 and type 52 though I don't think they are supplied in as many sizes as 43. Also could you try a fair-rite 2643625002 core, you can get them thru mouser. Thank you for your efforts and sharing the results. 73/72
Do you have a suggested winding pattern and compensation capacitor for FT114-61 and -52 Jer? I tried those a while ago and the "best" I could achieve was a single band transformer for 30m band with the -61 type. So probably better efficiency, but a lot less broadband. At some point I needed a break from transformer winding and gave up ;).
Edit: All my cores are FT140 variants -43, -52, -61.
Thanks for the suggestions. As I said in my closing words: "you always realize, you´ve not done enough". This topic could fill hours of Video.... 73 Manuel; DL2MAN
@@labcat73 I don't know, excellent function, low loss/high efficiency and good swr, across the entire hf range is a lot to hope for, perhaps a variable cap and some sort of swr indicator would be needed for adjustment. W7ZOI had better efficiency on 40 and 20 with a ft114-61 than with a ft114-43. K1RF says (p28) that the qrpguys "no tune endfed" setup has too little inductance on 80 and 40 using a ft114-43, modeling of it is discussed in the current july-aug '22 qex, p31, with some discussion of the fixed cap and swr. I really like what Manuel is doing, and while I am tempted to get one of the tinky K6ARK kits, I am not yet convinced it's the optimal configuration.
@@dl2man in K1RF's "The End-Fed Half-Wave Antenna" from Nov 2018, p 25, he says 3:21 with 22g wire on a fair-rite 2643625002 with a 100 pf cap is better than 90% efficient on 80 thru 10, and he says it's good for 5w digital, 12.5 cw and 20 ssb. The core is stubbier than the usual pancake like toroids used. I am tempted to try it with a k6ark pcb/bnc setup. Maybe the stubbier configuration will make a more efficient transformer.
@@jertres2887 You might want to look into MM0OPXs great work (he also commented here): ua-cam.com/video/nZ-G4hJCTSM/v-deo.html
Tuners are not so lousy, but some yes.
I agree. Z-Match is a great example of a highly efficient Tuner. However: The classic N7DDC or MFC Matchboxes turn your (non resonant) Antennas into a Dummyloads with a little Radiation, as the core losses are also present in those. 73 Manuel; DL2MAN
transformers, baluns, and coax are lossy so the best solution is put your output stage in the centre of your dipole as nature intended
Would be interested to see a source for "natures intention" ;) 73 Manuel; DL2MAN
That was excellent! Thanks for all of the work. 72 - AA4K
Not surprising as the turn*amps moves the smaller cores into saturation more. Say 50W=I^2*50Ohm so 1A, 50V RMS.
The smaller cores might benefit from #61 material on 10m.
For the lower bands an extra primary turn and the required extra secondary turns might help, but then again it might move the core closer to field saturation.
This is surprising..... it makes me wonder how you may modify your future builds on this information. Of course, I can't predict what you should do next, because your IQ is maybe three times greater than my own! So we will watch and learn from you as you modify your approach!
Try the FT50B-43. "B" version....This is a taller version of the FT50. Can be hard to find. Wind it as an auto transfomer and I get 91% efficiency. I run mine at 30W SSB. I use 2 as a 1:1 balun, or 4 for a bit more power handling that QRP. Try stacking 3 core of FT82-43. Wind 3 turn primary auto transformer. Similar efficiency. Try winding on FT140-43 as auto transformer and close wind the turns. Close winding gives best flux linking and best efficiency. Spreading out turns reduces linkage and loses efficiency. Running a separate primary and winding as bifilar has no advantage. Try the "standard" of FT240-43 as per "internet wisdom" and you will get.... no surprises from your tests here. SWR testing is interesting only, but lossy winding and builds have better SWR. Loss to SWR in short coax is far less than loss to lossy cores. WELL done on actually building and testing, a refreshing change from repeating designs that have considerable loss - and it is fun! enjoy.
As you have two transformers in series, the actual loss per transformer is HALF of the loss that you measured; that is, if you measured the power output from the high impedance output of one transformer, it should be half of your measured loss using two transformers! Thus you would be putting more signal to air than your results indicate!
Please watch the Video again, I explain that in the Video. I devide the results by 2 in my Excel Sheet....
I can see you're very disappointed in losing 25% of your power! (Yes, I also see that this video is a year old, so probably you've gotten over it.) But, this isn't as bad as you think. A loss of 25% is about -1.25dB. And how much is -1.25dB? On the receivers that are listening to you, it is 1/5 of an S unit. So instead of getting an S7 report, you would get an S6.8 report, but they would just round it up to S7 anyway! I know this seems ridiculous, but even loss of HALF of your power only amounts to 1/2 an S unit at the other end. Every antenna system has losses, and everything your signal goes through that doesn't have gain has loss. Have you looked at how much power you lose in your coax? I think you would be shocked. To avoid this particular loss, you could use a center-fed half-wave dipole. But there are good reasons you want to use an end-fed instead. Like you said, everything is a compromise.
All very true ! I got over it, I improved efficiency, I built center fed dipole and I´m still having fun, and that´s the main goal here. It´s just grown up Version of toys ;) Thanks for your comment ! 73 Manuel; DL2MAN
Thank you for that awesome video! Conclusion? Use resonant antennas? vy 73 de dl8cy
EFHW is a resonant Antenna ;) And works really well in practice. But nothing will beat a well tuned and elevated monoband DIpole. That´s for sure. 73 Manuel; DL2MAN