The name of this channel originated with some facebook "experts". In the early days of the pandemic when things were locked down to a ridiculous level, I stated that I had spent several hundred dollars on ferrite, had wound hundreds of transformers over a few months, and had measured the losses across all of them in attempts to find some lower loss options than the FT240 and FT140 singles or stacks which were being used by the masses. Some butthurt "expert" who was offended due to me stating that his 3 stack of 52 mix toroids were not efficient across all of 80 to 10 meters then told me to just shut up, go back to my evil lair, and keep making my useless transformers. So I decided to adopt this name and start publishing my info here on youtube instead of the facebook groups where they would delete my posts and/or ban me from their groups. The channel will not necessarily always be all EFHW antenna related, but this is how it started.
Thank you for injecting a lot of common sense into this topic. Please clarify some details on the coil you have at 2m from feed. I believe you said 9 turns on a 28mm PVC form. I want to double check on this, because there is nothing on the Schedule 40 size list that's 28mm OD. Nominal 3/4" is under 27 mm OD; the next size up (1") is over 33 mm OD. Are you using something other than a Schedule 40/Schedule 80 size form? Would appreciate clarification. Thank you!
Hi, it's a 1/2" PVC conduit coupler, not pipe, that is what it measured at. Don't get hung up on the exact diameter or how many turns or your tuning will never be right same if you try to just copy the overall antenna length it won't tune right either. It all needs to be tuned in your environment. It's going to vary with whatever wire you use, so adjust the number of turns to bring 10m and 15m down to where you want them.
@@evil_lair_electronics TU OM; understood. One still needs a departure point - a place to start. You know the adage, I'm sure: Cut long and trim to suit. For that shape coil, inductance doesn't change much with number of turns or diameter as long as the length of wire coiled up is unchanged.
Folks: All this talk about "my EFHW UnUn is better than yours" is nonsense. First off, much of the RU-vids showing how to measure a Transmission Line Transformer (eg-UnUn) is flat out wrong and misleading. Then they show you how low the insertion loss is (at room temp under mW of NanoVNA power) which only tells you whether you blew the design or not. I saw a guy load up an incandescent light bulb and make a QSO, but that doesn't make it a practical antenna! But RARELY does anybody actually TEST these devices UNDER POWER and measure the efficiency (at each power level and band) and watch the performance degrade and the spurious emissions climb as the core heats up. A notable exception is "Jim's Cool Stuff" which I give kudos to! But nobody had done a RIGOROUS test of any given core for a 49:1 UnUn to my knowledge, and believe me, I've looked HARD. It was part of my 4 month long research project delving DEEP down the rabbit hole of TLTs and CMCs. The result was my Presentation and Workshop at the recent HamCon Zion. Please check out the narrated slide decks under my RU-vid channel named Antenna Whisperer, Podcasts #12a and #12b. They include links to the PDFs of the slide decks for your reference. PS-I'm now working on that "rigorous test suite" and will publish a YT on it soon. Initial results are quite revealing (hint: efficiency is lower than you might think, even for a core which is not magnetically saturated by RF or heated from the lost energy).
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.
Q. I'm a new HAM and this will be my very first antenna build. QUESTION: Which outside turn does the tap/loop go? (2nd or 3rd) 2:55 ? I've ordered all the parts - Thankyou! 73.
I’m new to Amateur Radio, made a few transformers - different cores, winding schemes, capacitors. Settled on a similar design to yours. Got my first transceiver a few days ago, first time I PTT’d I was talking to a guy in Siberia 6600km away from the UK. Scientific method? I think not. Make my day? Certainly. Thank you Mr Lair.
Great stuff, excellent video 👏. I tested your winding scheme with my TX36/23/15-4C65 cores from DX-Wire here in Germany, and I measured the loss with two setups, using your test method. Now I know the loss: 40m not usable (-1.79dB), 30m somehow ok (-0.86dB), 20m-10m good (0.35dB to 0.55dB). Much better than my former setup 👍
Big follower and fan of yours. Wound 2 identical 49:1 transformers using the 61 material. Used plastic coated wire, separate primary and secondary windings, not twisted but bifilar wound, and close space turns. Back to back transformer test results very similar to yours. Back to back results: 7.088 MHz = -0.23 dB, 7.285 MHz = -0.20 dB, 14.07 MHz = -0.21 dB, 21.15 MHz = -0.53 dB, 28.23 MHz = -1.08 dB (divide these results to get individual transformer loss). Calculated efficiency on 40 meters 97.3%. Also tested back to back connected transformers on the bench running 100 watts CW and just noticed slight increase in temperature when touched by hand. Thanks, Don (wd8dsb)
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
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
You seem to be very quiet - I hope thats not because of the few as I can tell you it's the many not the few that like your videos. I hope the few haven't spoiled YT use for you - so nice your info - I'd call it technical but you use the word DATA which is very correct and what we need read to get to the facts instead of the fiction - I await some stuff late 2023 or 2024 your health being up to it. loads of EFHW stuff so far has been great tnx
When I was just getting back into ham radio I looked into a few facebook groups and online sites one starting with R also v big and was shocked at the outright nastiness on them - I have to say I been into Radio since 1980 and licenced mid 90s and it nearly put me off but then I saw such things as FT8 I'm not a user and thought well I cant' imagine people swearing at me on an FT8 QSO - hey maybe im wrong what do I know anyway I'm going to stay away from FB in general it has little to offer me. Now if I'm doing sales in the modern world it sounds like FB has lots to offer me - start a group where you sell items , delete everyone elses post that sell an alternative to what I'm offering or doesn't promote my items - yes FB is God isn't it also. But again mr double EVIL whilst my interest is radio I'm going to find it far better to view your content here than FB's.
I normally try to take the moral high ground which on here takes some doing as I feel all alone amongst all the BS but its still one of the only times I can say PROPER PROPER EVIL and proper accurate into the bargain.
When is evil lair going to show us how to build the ultimate 10m qrp antenna, now 10m is smokin'? Lot of talk about J-pole versus 5/8 lambda versus dipole etc. etc... but which is best for qrp?
Build the transformer. Cut a length of wire resonant on the 20m band. Then set it up as a 10m half square on a beach near salt water. Have fun all day long working DX
Man, thanks so much for doing these videos! As someone who enjoys building my own antennas and transformers, the information you publish is incredibly valuable, and I really appreciate your critiques of the status quo with regards to the conventional "wisdom" of transformer building. Awesome channel! 😁👍
Proper evil review enjoyed that found you probably directed by the youtube algorithm from Colins videos all great content spot on and technical, thanks G7VYH
Self proclaimed antenna engineers usually argue among themselves as to why an antenna acts as it does, especially when they see real world differences from their predictions. You need to stop taking them seriously as their fun seems to come from arguing and acting superior. When it comes to antenna efficiency I put more faith in A / B testing than db claims. A / B this antenna against dipoles for each band (as a baseline), verticals (FEB), then against other antennas you think are so inefficient, and show real world on the air results when the bands are so-so. Bottom line, if an antenna isn't putting its signal out where it needs to be, minimal db loss' don't mean squat. More loss with a better pattern will beat it. 73 mike
So I've been watching your videos, I think you need to stop looking at Facebook, I did long ago. I find your argument that an antenna needs to be loss free flawed, my instructor often mentioned a close by naval radio base with three towers for the naval am radio. They always brought up the point that the system was only 30% efficient and said most hams think it wouldn't work yet there it was standing tall flashing red at night. You never take into account the noise floor of the antenna or in other words the ears of it, can it hear as well as transmit? But that is not all what you are actually after is an antenna that rejects noise and even at low efficiency if the S/N ratio is good that antenna might out perform a higher efficiency antenna that is picking up more noise because it is so sensitive. Sort of like how some people receive on a loop antenna and transmit on a yagi. Thanks. VK1NME
I'm so glad I found this video. I was using the eBay capacitors you mentioned, and in my particular case, I was seeing SWR increases in the upper bands, especially 10 meters, during transmission. This was more pronounced when running between 50-100 watts. I ordered and soldered in the TDK cap from Mouser, and the SWR issue is gone. I can confirm that those eBay caps are exactly what you described as "complete garbage". Thank you.
Hi, you convinced me with this video and the results you showed. I have such a core for the transformer you made for this antenna, so I'm getting to do one. Thanks for everything and greetings from Poland.
Hi, don't worry about such people, unfortunately they will always be like that, thank you very much for movies on the construction and measurements of transformers to the end-fed antenna. They say everything for themselves! Greetings from Poland.
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?
