How efficient is the best 100w End Fed Half Wave Core when stacked for QRO?
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- Опубліковано 30 лис 2023
- Link to the 2643251002 core on Mouser
www.mouser.co.uk/ProductDetai...
Link to the spreadsheet of results
docs.google.com/spreadsheets/...
How to measure core efficiency with the back to back method
• How to measure Insersi... - Наука та технологія
I work ten meters with two stacked 240-43 cores and found them to be quite suitable for 100Watts of SSB. Thanks very much for this video. You are really filling a hole of information that needs filling. Your research is making the EFHW anttenna more viable and efficient, especially for multiple band operation.
2 cores will handle 100w data modes with ease never mind SSB. This core will let you squeeze out a little bit more performance.
Colin filming in his garage when it is -10°C inside and even colder outside 😂
Good job Colin. I didn't realise the ft240-43 cores were good for 70W. I always stop at 50. I'll definitely look at your suggestions for a higher power set up.
FYI I have worked 10m SSB qrp DX with the EFHW on more than one occasion.
Cheers, Fraser MM0EFI
Excellent Fraser. A lot will argue the 240-43 will handle 100w FT8 but not in my experiments. Getting milder here in southern parts thank goodness.
Thank goodness it is getting milder. I wasn't doubting your efficiency calculations for 10m. I think I just got lucky. When 10m is open, a bit of wet string can sometimes do the job. 😊
Thank for providing the test results spread sheets and the video. Very much appreciated. 👍
Your welcome 👍
Thanks a lot for your interesting experiments that are backed with data!
Just an opinion otherwise 🤷
Thanks a lot Colin… another excellent video.
Thanks 👍
Love this content, excellent work.
Thanks 😊
top work, as usual Colin.
Thanks Stu 👍
Excellent ! Thanks for sharing !
Your welcome 👍
I have not used this core yet but plan to. Looking forward to your tests. Thanks KW4EMF.
Your welcome 😊
Awesome results!
Try 1500w on FT8 to get some heat in that garage.🥶😁
Shame, my linear only goes to 1000w 😉
I use a 240 43 core. Works great on 40-10m 200watts!! I use a fan to cool it.
For reference I was using a single 240-43 as a 9:1 for a Random Wire and had the 70W limit hit me ..not imediately but after a good dose of FT8 also the operation at 10m again seems a bit off.. nice to see that your figures approximate to my setup done independantly!!
Thanks, there is some doubters out there but good luck to them. Yes, it does take a while to saturate the core but does happen.
@@MM0OPXFieldRadio I would say from the time it takes you are not Saturating the core significantly but enough to slowly heat it near the Curie point at which the performance drops and you are forced to back off to the sustainable level!!
Hi Colin, I'll be making a couple of antennas up with the 2x2643251002 cores stacked and giving them a good test on FT8. Also also 3xT290-43 with 3xT140-43 slipped inside, should be interesting to measure the efficiency of a very large transformer. Have you tried 2643101902? I have done some test on these and with 49:1 wide spaced the efficiency look about 90%+ from 80m-10m and is looking like a good option to replace the T140-43 cores from my products in the future. 73 M0VUE
Hi Chris, I would be very curious for your results. Theres still lots of experimenting out there to do. I havent tried the 1902 core. Its good to see a UK seller selling the 1002 core. Not easy to get hold of this side of the pond.
@@MM0OPXFieldRadio Hi Colin, send me your address and I'll post you a couple of 1902's. I've tested 80,40,20,15,10 my measurements were 93%, 92%, 92%,93% 90% efficiency using 49:1 wide and back to back with my Nano VNA. Would be good to see how close you get to these numbers as well.
FWIW I have used 2 T240-43 stacked in an EFHW at 400 watts SSB and it has survived 3 years now. I used 10 guage magnet wire for the 49:1 windings. Cheers.
You will on SSB no probs 👍
I build a 49:1 with 1 fair rite core and I'm allready amazed with the results of it.
I got it now up and running for 3 weeks ..... ok yes you got the changing band conditions but overall ... it does now allready do a much better job then the 240-43 core for sure.
Thats great its working for you 👍
I’ve become addicted to half wave end fed mono-band verticals for the higher bands!! I’m using ladder line to create a quarter wave shorted stub to give me a match! I find it a nice alternative to using a transformer when looking for DX!!
Definitely, I really like my monoband 5/8 vertical L/C matches. I can run much more power vs a wound ferrite core.
shunt stub or series stub? sounds interesting. wonder if it is more efficient? or you essentially using a 'j-pole' on the higher bands?
@@Gabaab It’s essentially operating as a j-pole! What’s nice is that the losses are low - the only area of high current being around the shorted end of the ladder line. So quite efficient!
@@Sinaisid i am going to try this myself. though probably anything higher than 15 m would probably be a pain to do in real life...
@@Gabaab It's worth a try - easy to make and v effective. For 10m I've always thought getting the 5 m wire as high as possible on a 10m pole helps - Height is might etc etc!!!!
This video is semi helpful :-)
I have been playing with magnetic loop antennas made with 1” x 1/16” aluminium bar.
Using FT240-43 core as a 1:x matching transformer, I have 40m and 20m working exceptionally well with both 8m and 5m circumference loops.
However, using the smaller 3 and 4m loops for 10-15m the turns ratio drops and the coupling efficiency seems to die off
Stacking cores helps a bit and I grabbed some type 52, 61 and 77 material. Not much difference.
Strangely enough the throw together 10m loop I poke out the window made from 2.5m of RG6 with a capacitor made of the same, fed by some random EMI filter cores I found in a computer case is around 12-15 dog biscuits better to the local RBN
I’m considering the core efficiency vs the skin effect issues of a flat bar vs round
Might look at other coupling and matching methods. Small loop, gamma match. See what works.
Sadly these cores you’ve used are too narrow for the strap.
Back to the experimenting….
Sounds great. I love loops.
@@MM0OPXFieldRadio they are magic. The noise drops from S7 to S3 on 40m with the 8m circumference loop bs the 33’ vertical. That’s what you get for living in an inner city QRM jungle. Seems quieter since they took away the overhead cable service amp from out front.
It’s the coupling that I’m working on. I’ve seen a few of your videos on materials v frequency and they have been very helpful.
I think it’s because the loops are almost too long and with a single turn through the core the impedance at resonance is too high and I don’t get a tight enough coupling with so few turns. The match is good, but the energy transfer is crap.
That said, I don’t see heat in the core.
Back to the drawing board and more experiments.
But I have succeeded in a _Poke-Out-The-Window-Tenna™️_ that covers 20m and 40m so I can test radios from my test bench
@MidlifeRenaissanceMan Thats amazing. Ive always wanted to build another mag loop. I had an 80m horizontal loop years ago which worked very well.
@@MM0OPXFieldRadio I have managed to drive 100W into this current design. Works well and no capacitor flash over.
Trick with mag loops is don’t expect them to cover more than an octave of frequency. 7-14. 14-28. You can certainly tune them down there but their efficiency drops significantly below the first octave, and you can hit self resonance up top.
Efficiency is proportional to the surface area so circles and octagons tend to beat squares.
Radiating Element surface area is significant to a point. But skin effect is your friend. You can get away with tape, either aluminium or copper. Much cheaper than copper pipe, though if you’re happy to slip a dude a $50 he can take a $30 aluminium pole and bend it into an almost circle for you. Friend has one that he can tune 7-21MHz that performs OK on 7 but really kicks some at 14MHz
Finally, you only need a small amount of variable capacitance to cover any band. Makes it cheap to build a mono band loop and change bands by paralleling fixed capacitance across the variable cap.
Probably stuff you already know, but someone may come across the thread. :-)
Great work Colin... I wanted to try a 49:1 2 stack 52 core, which I don't think you have shown, and which I think will work better on 12 and 10 meters... am only interested in 40 and up. I only had a single FT 240 52 core. Looking at most winding profiles, sans the crossover which is NOT necessary; so you have a winding profile uses less than 1/2 the core mass... the rest on the other side is wasted.... or is it?
Carefully using an angle cutter I chopped the core in half, you do this carefully, score the first side down 1/4 then do the other side, it'll fracture apart, clean it up.... and then glue the 2 halves together. Since size matters, I now have double the mass under the windings; that's what you really want. I only run 100 watts SSB max, most of the time it's only 20 watts from my Xeigu G90....
Preliminary results are positive....seems to work well, VSWR is less than 1.5 on all bands, 20 and up including 12 m ... until you get to 40 where it went a bit askew and resonates a bit high in the band... 80 is useless, which I kinda expected. Worked a guy in Kentucky on 10...got a 5X5, but more checks are needed.
Thats a really interesting idea. I would need to do a back to back with chopped cores to see if if makes a difference. I doubt I will though as these are not my cores.
Hi Colin. Great videos. I"m in the process of winding 2 stack of 1002 toroids. Looking at you chart it refers to "14/2 turns wide spaced" I wasn't clear if that differed from the tightly wound and spaced auto transformer. I might be missing something but I've not seen "wide spaced" demonstrated in any of your videos. Clarification would be appreciated...thanks.
I still have some updating of the spreadsheet yet. Wide spaced means just evenly spaced out windings. Your 2 stack of 1002 will be very good low down but become very lossy above 20m. Let me know how it goes for you.
What size wire are you winding the cores with. My club has been experimenting with a 36:1 winding that is interesting.
For this test I used 0.66mm wire as it's easier on the fingers. For use as an antenna use something about 1mm in diameter. I have 1.12mm and 1.18mm here also.
Huge.
Others probably done it already but not shared.
Thank you for supplying your viewers with such amazing data. I am building a EFHW now and putting my 240 43 cores aside, 100 watts max to include SSB and Digital. Ordering the new cores, but now confused with the best way to go, single core or stacked?
I'm no expert, just sharing what I can. 1 x 1002 is perfect for what you need and will run FT8 all day at 100w.
@@MM0OPXFieldRadio Thank you sir!
I've built a 2/14 closewind, at tapped, 100pf using Fair-Rite - 2643102002, using similar test rig I get results inline with the Fair-Rite - 2643251002 and Fair-Rite - 2643625002. I've been using it for POTA w/ 20m~ of wire and it's been matching/surpassing my results from ft-140-43 I was using for 10-100w (usually I activate 10 or 50w)
Excellent, glad you got something that works for you 😀
Hi Colin, got another question ....
Have you ever considered to try and test a 9:1 comparison between the 240-43 and the Fair Rite ....1002 core for the EFRW / EFLW users between us ?
Will the efficiency of the 1002 core be as good there too ?
I'm gonna build and antenna like that. Goal is to get on the warc bands too.
No, I havent. Thesmokinape has done some videos on this and a 9:1 is pretry good 90% plus. Of course you have SWR losses. It would appear the less the impedance transformation the less the efficiency losses.
Two questions:
1. Is it possible that using a larger value shunting capacitor to negate some the high inductive reactance at 10m ...could decrease that really bad -4.55dB loss?
Or does that merely change the total impedance at 10m?
2. Would it be ridculous to think about a hybrid core combo? Since that actual transformation is occuring in the core of the toroids, maybe trying a single 1002 core centered and sitting squarely on top of an FT240-43? Or would one core just take all the loss anyhow?
A 4.5dB loss on 10m with two 1002 cores would be excessive and the core heating would be unbearable. I'd rather just use an antenna switch and go to a different antenna on 10m.
1. Possibly but think it would adversely affect the match as as antenna.
2. Not at all. I think its a possibility. Can only try.
3. Agreed, there are many better antennas for 10m.
WHAT happens if you mix the cores ? like, the 43 and the 52 together ?
I’m very interested in your work. I would like to build a transformer that does 80, 40, and 20 at least and with full legal US 1500w power on SSB for use in our ham radio club for possible emergency communications. I have subscribed.
Ive made a more recent video on this. You need a 3 stack of 240-52 wound as an Autotransformer. Its as efficient at this (maybe slightly better) and will handle your power.
@@MM0OPXFieldRadio Thank you. I’ll find the video and watch it. I truly appreciate your data driven analyses.
I have not seen anyone else use this. Thank you for making your video, but are you aware of anyone who has corroborated your experiments?
Not on youtube so much hence why I made this. If you look hard enough you will numerous others on facebook groups and Twitter have done this and coroborated results, particularly on the 1002 core. Look at this ua-cam.com/video/liobaos7nhs/v-deo.htmlsi=lQRqyNHX8fgLeSBi
I'm curious about the efficiency with larger diameters of magnet wire.
Compared previously. Made no measurable difference. If im just testing I use thinner wire thats easier on the fingers.
Makes no difference because if you push the power limit of the smaller wire the core would have already been saturated in the first place.
What's the best wire length end fed antenna measurement for 10 mter to 80
Impossible for an exact figure as this will depend on your environment. It will be in the region of 130ft / 42m
Im curious where you place your common mode choke on the ciax or do yiu use a counterpoise or both?
Usually I don't use either. If i do, its a GM3SEK choke 0.05 lambda away from the feedpoint at lowest operating frequency.
@@MM0OPXFieldRadioSo what would drive you to use a CMC vs not? Simply not getting it to tune?
Common mode current coming into your
Shack but could manifest itself as a tuning issue.
@@MM0OPXFieldRadio i have a CMC at the rig but always thought you HAD to use a choke approximately. 5 wavelength down from the feed point
0.05 of a wavelength from the feedpoint ideally. Dont fret about it too much.
Well that 21/3 didn’t look bad 80 to 20.
Which core 140-43?
@@MM0OPXFieldRadio 2643251002 80:94.84%, 40:94.62%, 20:93.11% which is very good; 21/3 close soaced 100pf. First column.
Can I send you a heater mate, I can see your breath hi hi.
Yes it was just a tad chilly Brian 🥶
How about a 2 stack 56:1? 3 stack :) ?
Tried it already. Stacking these cores makes the higher bands worse. 1 core is the best balance.
Mouser link = "Sorry, we can’t find the page you’re looking for." 🤔
Try now, should be fixed 👍
Fixed. @@MM0OPXFieldRadio
code described and link go to different core?
Just search by part #
@@alanjones3873 looks like the right core to me.
why so much power on ft8 i worked the world on 10 watts. running your radio to 100watts or amplifiers on ft8 will kill your output transistors. better antenna less power.
I agree in general. To he clear, FT8 is a weak signal mode, not a low power mode. There will be times you need to raise the power but yes usually if the band is open a few watts will do. I wouldnt run more than 30w from my rig on a digimode. My amplifier however would run all day and some at 400w. Its rated 1kw full duty cycle and I know a friend whe had an NOV and ran his on 1kw RTTY without issue which has a higher duty cycle over FT8.
Knew a bloke who during the recent sunspot minimum worked Australia to east coast Russia on 10m using _Russian QRP_ which was around 2KW to get through on FT8
I guess you do what it takes :-)
LDMOS has made it easier :-)
I just want a core that can do 10-80, 🤣
Ready?
A 240-43, 2primary 16secondary, as close as possible, (obviously no cross over crap), tapped not bifiller, 100 pf, I got the 5t on 1" former inductor 2m from the box, then a few hundred pf cap directly in the middle of the wire for the 75mod, feed it with 75ohm coax
Most wonderful end fed I've ever made,