Відео

I really love your videos about efhw transformers. As you said it’s definitely a rabbit hole but you and Owen do real testing and it seems you are improving the designs each time !! I followed your spreadsheet and used the qrp autotransformer version 21/3T. I just noticed while unwinding some turns that there’s a little dent in the inside of the copper enameled layer each time it touches a corner of the toroid, is it fine as long as it doesn’t touch the other turns ? Do I apply too much tension ? Any tips ? (The core is really small)

matching a 1/2 wave with an autotransformer is so much easier that I have to say it's a push on which is best. if you create a lossy matching system for 5/8, any small advantage will disappear.

As someone kind of new to making them, I don't know why you put the windings close together? I have only made one and I used about 3/4 of the core for my windings. You used about 1/4 of the core. Is it better if the wires are close together? I do NOT do the crossover method. Just looking for information to help me make better ones! 73 W4DES

I have one on my roof only 20 feet up and i can make contact with Europe and the south pacific no problem when theres conditions of course. This is on 10 and 11 meters

Made this antenna today, following your design closely. Worked wonderfully! I found the angle of the radials and height of the LC box moved the SWR around a bit. First contact was NL7V - Alaska, using 25W! I have the 12M Spiderbeams pole and am going to attempt 20M band by wrapping the wire around the pole, widely spaced to avoid inductance and just enough turns to still have a metre or two above the ground. By the way, I have also made your Moxon for 10M, it’s my favourite antenna. Thanks for all you do to help novice amateur radio operators like me. Best regards, Kevin M7XOM.

hello colin, I rebuilt the balun with the 2643251002 and it works well with my endfed antenna. However, I can't get any resonance in the 6m band. It works with the 140/43. Is the 2643251002 not suitable for 6m?

I've watched this and the 20m build. Could i build the 20m moxon using this same design. I would be guying the element poles to the top of the mast. This would make it a little more portable for me.

Will work for QRP? Thanks

Does the Autotransformer also run with the FT240/43 ?

Did you take inductance measurements so one can determine the range of where best eff occur over the HF bands. It is of course possible to calculate ind but actual measrements will be FB. Great adventure and tut.

Hi, thanks for this. I think there can be a hazard using (sloping) quarter-wave radials, as their currents are out of phase with the main radiating current in the vertical radiator. As yours are almost horizontal, that might not be a big problem, but could be worth modelling to see whether there is a compromise in the low-angle performance, and possibly a vulnerability to extra sky-noise from a high-angle lobe. 5/8-wavelength radials probably don't have this issue, if they are strictly symmetrical. Hope that helps! 73, Tim

Thanks for all the detail. For greater bandwidth, some have homebrewed copies of the Sirio "Gainmaster": ua-cam.com/video/eboJV6rY4a4/v-deo.html

That is a thing of beauty. Thanks so much.

the links don't work for me What is the pn. of the core? pls

Thank you for the video! You’ve motivated me to make this my first home brew build! I just passed my General exam two weeks ago!

Can we stack two of these for more power with the same turns?

GREAT VIDEO - Thank you for the info

Can you provide the specification of components which you used in your antenna? Thank you and "73"

Would it help or be of any benefit to adding some glass cloth electrical tape under the windings?

First time making my own unun. I was curious if i was going to eat it up doing ft8 using a stacked 240-43 with 12ga wire, looks like I should be fine. Thanks for the confirmation!

Thanks for usefull info. You might also have a look at the DX wire masts. They rods are 1.5 mm thick, making it a very sturdy mast that hardly moves in the wind. You can even mount a rotator on it at 5 meters height.

Make a video about balun or unun using CRT Yoke core.

Great job Colin and very clear explanation of details👍. Thanks for sharing your knowledge. Do you think this design can be suitable for a stable installation at home?

You clever chap…. 💙 Pity you’re not going into production but I understand why. You’re a good man sharing these things. Well done Sir. G0UvL

You clever chap 🤔

You’re a good man… doing all the R&D then inviting someone to take the design and market it…. I hope it’s a local Scottish workshop that takes it up. 73. 💙 G0uvl

Thank you for sharing,inspired me make my own one. Can you tell me how long the centerpost is from the plate to the top ( is ist about 104 cm)

can you please show with the nanoVNA showing which swr graph do you get with the resistor test? attempted to build a few times a 49:1 using this fair-rite core and never got any decent results with the 100pf capacitor, it creeps up passing 3swr after 17.240 until it tops up at 5.51swr at 26.810 and then comes back down again. I have successfully made the same exact design with the same wire and capacitor on a dual stack of FT240-43 with almost a flat SWR curve all the way up to 30mhz also if possible, can you test FT290-43s with your method? I've been curious about that core as a replacement for my 2 stacks of FT240-43

10/11m skypper is just as easy cheap and will knock spots off a moxon. Been there and got the T-shirt

My son and I have made one of these per your process. We will be hooking it up to some wire this weekend. I plan on trying about 140 foot of wire and seeing if I can tune it as a spooler antenna. We considered doing it as a linked, but want to see if spooling it in and out will serve to get resonance on the bands.

Nice data sheet. Will try to setup my new antenna on that.

NIce antenna. Hexbeam is quite popular in this region, though not owned by many! 73 de Jon, VU2JO

Any suggestion on how to make this build resonant on 75 meters? Some content creators insert a capacitor at some defined point, but their build is different. I enjoy this antenna, and it works beautifully. But I'd like better SWR on 75 m. Thanks.

Hi Colin, many thanks for all the work and information. I am now living in Malawi, so *nothing* is available here. I have decided to follow your build plans and will order all the parts from the BOM and get them sent here. We'll see how it goes... Marc (7Q5MLV)

I think it was a design from GM0ONX if I remember correctly.

thanks for good info. how would I make a 64:1?.. 24 turns secondary and tapping on third primary ( same as 49:1 )?

Great video and build. Would a shortened element (loading coil in the middle) work in a hex beam setup. I've passed your area today I am currently a MM7. Up in Aberdeen, back home tomorrow. 😊

Is there a video done on the stacked 240s?

How did you calculate dimensions to get 50ohm?

Many thanks G0INL

I'd like to know, if anyone who lives in suburbia, uses one...What do the neighbours think?

Can I put a comet GP-9 on the spider beam?

Hey there Colin. First off, thank you for the content your making, its getting me good into HF and HAM in genarel. But i have a small problem with the 2643251002. I have made 4 builds now with 13, 14, 15 and 16 turns, and with deffrent copper wire both deffrent in make and size. No matter what my graph looks like a mad house. :) from around 15Mhz and up its over 2:1 SWR with testing with a 2450 Ohm load. Question is how the hell do you and the rest of youtube land make this work, most videos i have watched, just build it like i do and its spot on. Side note did a 49:1 on a 240-43 to see if it me who is not doing it right. That one has top SWR at about 30 Mhz and is 1.7:1 and a nice low curve. What am i doing worng here. Sorry for the bad gramma. Cheers Vy 73 de OZ5ZX // Jeff

Colin, Thanks for the ideas as I put together my DIY hexbeam. The only thing you are lacking is a 3d printing setup. So many times I have seen in your videos, places where I would just print something like you are proposing. Once you start with 3D it opens so many doors. :)

BRAVO Colin, 73 de 4L4FN !

I solder the tap on before winding. Wind a few turns so you get an idea of where the tap needs to be, take the wire off, solder, heat shrink, then wind the coil. Keeps the heat away from to ferrite and allows a more secure and insulated joint. My problem is that the efficiency is crap on 10 m. I built a 3:21 autotransformer with a 2643625002. Colin's testing showed good performance all the way through 10 m. Mine are fine at 15 m but about 7.5 dB down at 10 m for a pair back to back with 100 pF capacitors. I've tried re-building them with different wires and they are all about the same. Can't figure that one out.

Great intro and walk through 👍🏻

great work colin ,many thanks for shareing it ,73 de 2m0etj

Colin would there be much work to add 20meters to this design?. Thanks for putting the time into the design and sharing all the details to build a completed antenna.