Which end fed half wave transformer should you use for running high power?  

Thanks Ape 👍

Yep, you never hear anyone talk about losses, efficiency, and actual repeatable results from testing. Just opinions and like a butt we all have one and they all.....

I wouldn't call myself an expert, just an experimenter. I have a suspicion the 52 marerial tests had some measureny error. They still wouldnt be good across the whole of HF. The search for a QRO core goes on.

Check out my later video. I clear some things up and these are not as bad as thought.

Your very welcome.

Options are nice, not a good as data though.

Thank you. I try to make them that way. That's the trouble I used to have also.

Appreciate the comments Erick, I do my best to keep the waffle to minimum and get the information out there I think is relevant.

Excellent, please share your results.

Your welcome.

Thanks 👍

Thanks.

No problem 😊

Thanks Chuck. Those 11mm poles arrived. Still to test the tension but look decent.

Your welcome.

Certainly every antenna gets its 15 minutes of fame. As long as we are happy then thats as good as it gets.

Fine Business KE4TDG

I agree in principle. I wont however be tunning Digital or CW at these power levels. That's crazy. Im likely going to run 800w max SSB and it cruises at this.

I haven't seen anyone better this for a 100w core. Remember you can run 100w FT8 with the 1002 core.

Just depends how much power you want to run.

The Smokin Ape has started to make these measurements and the results look very positive. Check it out if you haven't already.

I compared 49:1 and 9:1 on FT140-43 cores and 9:1 was far more efficient than standard 21:3 and a bit better than KN5L method of winding using 28:4 turns. 9:1 was 3x5turns

If you do, let me know how you get on.

Thanks. I have seen this method but still to get my head round the maths. I need to try this for an existing. Yes I agree there is room for improvement, how much I don't know. It may be significant it may not be. Only one way to find out.

I agree about the lead length, for both the transformer and the capacitor, and have seen a small reduction of loss by making this as short as I could. However it was only about 0.1dB and was only around 10 meters, the rest of the trace was virtually identical. I'm sure it would be worse with more frequency, but I don't know why anyone would want to use this type of antenna above 10 meters anyway. So yes any test jig is going to have some lead length and show this loss unless you really push it, making it far more time consuming when testing a ot of transformers, and the same is true when you put the transformer/capacitor in an enclosure and connect magnet wire over to an RF connector unless the enclosure is really a super tight fit for everything. This is one reason why I started making circuit boards and connecting the coax directly to them, the lead dress is reduced to the lowest practical level. I drew a board for a jig this week to do the single transformer tests which will have a 2.4k SMD resistor on it(VNA port 2 of course already provides 50 ohms of load). I'm interested to see if a single tests much different than a pair. Other problems we can't do much about, like permeability vs temperature, if you look at 43, it's about 750 at 20C, but double that by 95C. 52 is not much better, but 61 is WAY better.

​@@evil_lair_electronics I've suspected the 61 was the better choice based on curie points from mfgr data.

Best of luck 👍

Conditions certainly improved but always helps having the edge.

Murphy's Law dictates that when ever a new antenna/transformer is tried the "on the air" HF conditions will never be typical but will be "fantastic" or "less than favorable" hi hi. Is always best to try an antenna for a week or two to fully get a feel on how well it is working. The Black Magic of RF and Ferrite material is a fascinating and addictive subject, as I am discovering ... !

👍 👍 👍

I will look up that core and see availability. it would be good to try.

@@MM0OPXFieldRadio I made up a binocular core from 4 FT140-43's it's really ugly, but the the efficiency with 4 turns comes out at 98%. The core I mentioned above was the one you were recommending in your video, it's not a new one from me.

Thanks. I think inductance is playing a part but cant prove that.

Yeah I forgot. I added it this morning 👍

I know. Perhaps the geometry is a cause of this effect.

I wouldn't be surprised. I tool agree, mono band is always best when possible.

On the chunky 1002 core I tried both and there was no measurable difference. There may be with different cores though as the hole is larger.

So I was doing my tests with 0.6mm wire and for your needs go with something around 1mm. I've used 1.12mm and 1.16mm.

@@MM0OPXFieldRadio okay, more questions, but see? that's what you do, you make us think and not just copy things! When I look at your worksheet for the 2643251002 for 100w (I think the 5th tab in your document) is this a single core? or a triple stack? It looks like a single, and if so, why do a triple stack when a single stack looks so good (again, just looking at your spreadsheet). If this is a single you are documenting in that tab, it seems really like a close race between the wide turns with the crossover and the close turns. Also, if I use this core and this winding, would it hurt my efficiency ratio if I did QRP on this one too? I mean, my goal is 100w, but was just wondering how QRP on that same core could have any negative consequences?

No, I dont plan on either as I think there will little gain if any over 43 or 52.

The wire was 1.16mm diameter. The wire is just high temp enamelled copper wire but its not critical. Its actually a pain to scrape off as it wont "tin" off with solder. I buy from Brocott here in the UK.

Wonder what the mix is?

Yeah just sweeping for an SWR curve doesnt tell you anything about the efficiency. Some people do however.

hey 101blog, I've made just that. stacked stubbies x2. primary winding with 1.5mm2 enamelled and secondary winding with 1.25mm2 enamelled. in a 49:1 config. No testing like our man has done here as yet though.....

I havent stacked these but I have stacked the chunky QRP cores. What happens is the the low bands get marginally better but 20m and above falls off a cliff unfortunately. The same will happen here so based on experience no point in trying to stack these.

@@MM0OPXFieldRadio OK I read ya, I've ordered 3 from Mouser so may well try stacking them for the sake of knowledge. Thanks again for producing a well collated and consistent body of test results !!

You need the core ending in 1002. Have a look at my previous videos for one of the best 100w transformers.

I hadn't but you are the second person to say this. Maybe some 61 material in the mix would be good.

I think there is a commercial choke that implements just that wont mention names but there a long rounded balun which is sold that mixes different types. I think mixing it up can improve results and coverage across the HF range.

I think someone's done a stack of two 43s with a 52 in the middle, or maybe I made that combination up in my head, I'm not sure what's real here! 🙂

I don't think so. I beleive it will improve lower bands marginally but at the expense of the higher bands.

I doubt it, I have very little wire left either unfortunately.

Whats the difference with a K core?

Not specifically no. If you search "end fed half wave Autotransformer" you will get numerous diagrams. If I can get time I will make a video on this.

Thanks, I'll check that out. Thanks for the videos they're very helpful@@MM0OPXFieldRadio

No but I think if that did work perhaps 61 mix might be needed.

@@MM0OPXFieldRadio yes I agree

Not quite sure how you think I feel differently? This video is regarding the transformers only. At no point in any of my videos have I ever said only focus on this, field testing goes without saying. WSPR measurments are great but only if you have a reference. In order to conduct whats better i.e A or B you need simultaneous WSPR RTX on at least 2 different antenna for the same band in the same proximity. Only 1 person I know does this and that HB9VQQ. Look him up if you dont know him.

Thats just a 56:1, the winding style is no different. I'm done with testing these for now.

ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Xe0wvbOQeok.html

@@MM0OPXFieldRadio definitely need spoon-feeding. I figured out the winding pattern I think, took like 20 times watching it though and examining the core from every angle Cheers!

Not at all. We all learn somewhere.

Thanks, your welcome 👍