HomeMade 80M Band Coil for 40M EFHW Antenna 

Hello Paul, you really showed how it works. I did it the same way. My coil looks a little different, but in principle there is no difference. But I don't cut the wire around the resonance anymore, I just fold it. It's less of a thrill, but it works great :-)

Sir your attention to detail and application of easy to find hardware is some great stuff.

I prefer to not use soldered connection for wires that might move around due to wind. They tend to break after a while. To prevent this a clamped connection is better. But I hope you won't have this problem. That coil looks great. Professional work! 👍

Paul you could add self amalgamating tape to the coil without adding to much weight if you think environmental conditions need it. Good video plenty of technical content. Worth a try. Regards

Very cool video 😊 i like your channel! 80m and 160m antenna Videos are interesting 73

The built in ATU will tune the 3:1 down to perfect but THEN you can use that tuning and turn the VFO further to beyond the perfect match. For example, dial to the furthest point your radio will tune, get the perfect ATU match, then since it is now 1:1 you can turn the VFO further to say 2:1 and TX just fine. It is the equivalent to the 5:1 point but tuned down to 2:1. You don't have to stick to the sub 3:1 bandwidth.

Just a though, when you got closer to your desired frequency, folding the wire back rather than cutting may be a better option in hindsight. Great video. Thanks

Very solid build. I would have run the wire to within about 2m of the pole (the longer the better) and then reduced windings on the loading coil. You can do that by shorting windings. Scrape the enamel off one winding at a time and form short bridge with a dab of solder. Repeat until you get very close. Then perhaps fold the wire to bring the dip to where you want it. Less inductance (less windings) will widen the bandwidth and thus improve your SWR at the band limits. I don’t have the space at my fixed QTH to put up an 80m EFHW but the above method is how I got my 40m tuned for maximum SWR width in band.

Wie sieht ein Lötkolben aus?! Sie können es auch sehen, herstellen oder kaufen, sehr interessant...?!

Good video. I do lenght adjustment so that fold extra lenght backwards and hold it in place to antenna wire with straps. That allows you go back and forth with wire lenght. When final lenght achieved I cut that extra tail off and secure folding point permanent. That way you dont make your wire too short and need new wire. 😊

I never cut the wire when close to the wanted frequency. I bend and fold the wire back, take a look at the chart. If to short I make it longer with the bend over piece. When OK I then will cut the wire. I like your videos. 73 Phil ON4VP

friend. piease show me the soldering iron. very interesting. this is the one in the video ?! thank you

Can you just fold back the wire to make it shorter rather than cutting ???

I quite like the look of this antenna as it appears to be not too difficult to build. How did you arrive at the turns of winding over the diameter of form? Is this one of the online calculators and if so which one? I have tried a few and it always appears that there is a capacitor of some sort involved in parallel with the coil. I (Canadian) have never seen the type of fitting you used and would probably be winding a coil over a regular 2" (50mm) PVC tube, I would expect that would change the turns of the coil. A couple of things. It's been my experience that the self amalgamating tape (splicing tape) is not UV stable and requires a layer of electrical tape over it. I have used it over PL259s and it deteriorated in the sun if not covered. I am not sure but I don't know how UV stable the enamel coating on the wire is either, but I have seen a few traps built out of it so it might be fine. It looks like another trap and you would be able to build a 160m extension. I have been looking for an antenna to build so I can get on the air again. A tree ate my 4 band TET beam and tower a few years ago and I'm working to get that up and running again (TH7 this time and the tower is a piece of crap). Anyway great build and 73 de Gil ve7bul

Very nice bit of work Paul, store bought wouldn't come any nicer. A few thoughts...there seems to be a narrow range of 'European' frequencies that are of interest to you, and so the loading coil being large and of relatively high Q reduces you're useful bandwidth considerably. Considering the length of the antenna, I'm suprised it's so tight. You might also try to wind a new matching xfrmer on a Fair Rite core 2643251002, auto transformer style, and with no crossover... 56:1, just an extra turn (15) and you might just find the match to be much better, perhaps pulling the VSWR down to near 1:1... Doing this I went from 1:162 down to 1:104 on the NanoVna...as always YMMV... Richard VA7AA

Verry nice! Thank you for this Video 👍👍

I love how you demonstrate this with no words. Very clear. I'm regularly confused by many construction videos where the presenter says: "now we're going to {unfamiliar expression here}…" before cutting the video to show the thing AFTER they did the unfamiliar procedure, but didn't show me how. BUT I DON'T KNOW HOW YOU DO THE THING YOU JUST DID!! 😭 I understood you perfectly 😁👍🏻

Thankyou for the build video ,you did a brilliant job.

Nice… I made one as well. I used a smaller diameter form. I kind of regret it since it ended up being almost 12” long to get the required inductance haha.

Jan 2024: A waste-pipe coupling I have not seen in North America but that looks like the perfect form for such a coil.

Hey Paul, great video. Here in the United States, we call that plastic insulator a "dog bone." -K5SFC

Very Helpful especially with your used fittings many thanks GM4NNC

I see a lot of people asking about the coil. I see that you have the 40 meter antenna but making an 80 meter antenna would require double the garden size. Presuming you don't have enough room you decided to make a loading coil. The chinese loading coils that they put in the JPC-12 antennas can be had cheaply and they have a slider that ahorts them at different inductance values. I wonder if one of those would have the amount of inductance loading you need, and i wonder if it might have worked in your application. It allows the JPC-12 whip to run at 20 and 40 meters. Supposedly with a second one you can run 80. In any case, good video. I was unsure what you were going to be doing....i thought you might add a capacator to make a trap so that you could make a trap antenna. One or two slides in the beginning would have spared my weak brain much confusion.

Good job

Self amalgamation tape will deteriorate eventually. I have started using Denso tape. It will last better and is totally protective. Best of all it’s cheaper. 73’s John GM0MST

Would it be beneficial to cover the windings of your coil with house paint? That would protect the insulating coating from the sun, so it doesn't short out.

did you measure the coil microhenries value and did the addition of the 80M section change the performance from 10 to 40?

Buddy, you didn't measure the coil's inductance, besides, inserting metal elements into the coil's carcass changes its inductance!

Super.!

I would have like to see the readings of the other bands, eg 40m and 20m in terms of swr / freq. Thanks still a great video as always.

Or you could just make an 80 meter EFHW. Good for 80 -10m.

How many micro Henry is the coil and details of the former and length of the extension wire would be help full

Have you sold your Quangshen radio now...?! 😂😂

Your coil looks like it was factory made.👏🇨🇮

What is the value of the coil ?

What is the benefit of this antenna for us? Does it strengthen the antenna phone signal?

Very beautiful Job 💯👌

Hi Paul. Did you measure your coil when you finished the winding? I made mine on a 25mm plastic pipe, and when finished, I read 108.5 micro Henries. It is longer than your coil, but the inductance is probably close to the same. Nice project!

Thanks for the excellent build video. A TIP for you: As you found out the hard way you can cut too much. there is no need to cut. If you fold the extra wire *tightly* on itself, it is like a virtual cut. Try it. I am always astonished at the common ham advise to cut the wire to resonance, and people don't advise wrapping the extra length to achieve the virtual cut. 73

At 1:10 if you added a nut to the bolt 1st before anything else just to act as a spacer it would make tightening things up later on much easier.

I trim my overall wire length using two iPhones using the Video Chat method. #1 iPhone is in the shack pointed at my VNA, which is connected to the RF cable that is normally connected to the back of my radio. I then take #2 iPhone to the end of the wire and trim as needed. It something you can do by yourself.

What is the mH of this coil? Nicely done!!

Building a field portable use 80-10 EFHW right now. Mt current EFHW at my QTH does not utilize your version of strain relief. The loading coil that is used to widen the higher bands ( 10mtrs ) puts the strain on the PVC tube. I like your version much more. For the cost of a bit more hardware and time... This seems to be well worth it. Thank you... 😊 73 de KF4LBG Larry

This American would not be satisfied with it being just close enough. I would be altering the coil and wire length to get even lower swr on the freq I wanted. I would tune for a 1:1 swr on desired freq.

Your wire looks like 12ga, or 14ga, is it?

Paul, neat build for your coil and then figuring out your 80m wire length. I learned that it is much better to fold back to tweak an antenna to reach the residence that I want vs. cutting too much. You can always cut the wire once you reach the right length.

Americans were SCREAMING at the screen, telling you NOT to cut your wire!

Hello Paul the god job......73 EA4HHX 🇪🇸 YV4GJN 🇻🇪

If you are testing lengths, you can just adjust the wire in the clamp, instead of cutting it. That way, if it get too short(for some reason :-) ), you can just let some more out of the clamp. Good job.

Nice video for 80m band coils home brew. You are sharing a good ideas for making coils. Adjust a SWR is normally takes a time to cut and try Ha Ha... de HL1SB

thanks for providing interesting information on DIY efhw antenna with 80 m extension. What transformer is there? And what core mix?

Very nice indeed! 👍

👍

one suggestion I would make is to not cut the wire when you are close to resonance, but leave it a foot or so longer and twist it around the antenna wire. It will not affect the swr and you then have the option of lengthening it if necessary to fine tune. Once you have confirmed the length then you can cut if you desire, I tend to leave a bit for future adjustments if necessary. As you discovered, once the wire is cut there is no going back.

instead of cutting the wire just fold it back on itself untill you determine the length. then.... cut off the surplus. I wish I could afford one of those testers.

Good idea. Unfortunately a bit to heavy

Hi, is 50mm the form outside diameter?

Hi, and what about the tuning on other upper bands? Sometimes the use of a serial capacitor on the lower band wire part can reduce the missmatch on upper bands.

Nice build. I was just wondering whether the steel brackets inside the coil will have an effect on your inductance. And another one is.... will a lower value inductance coil with a bit longer extension wire give a wider bandwidth on 80m.?

Enjoyed watching what all us hams do! Messing around in the backyard with antenna's, but some of us getting to old to do it Paul. The trap looks really good and a great job! I thought you should have a insulator on the end where you have the rope connected too? Hope to get out in the backyard again when the weather gets better to play antennas, just as you have. Great to work you on 20mtrs the other day, shame about the qsb that spoilt the chat, hope to catch you again soon . keep up with the video's there great! cheers colin.

Thanks for the great construction techniques. You are a superb technician.

in future, do not cut the wire when you are close, fold it back and wrap it around the antenna length. this will allow you the adjust it back to a longer length if you guess too short.

What was the length of your 40m antenna? Did you have exact measurements?

Fantastic build but please fold back your wire for adjustment as you cannot undo a cut.

А,переклад не можна було зробити? Більшість читачів не володіють іноземною мовою!

Nice job. I am also working on a new antenna project like the one you built. The mini sweep analyzer looks like what what I "need ". HI HI. 73 Leo k

Looks Heavy ? ☝️🙄

i got some cheap candles and melted them in an old pan and coated my coil in wax.

What turn coil end meter antenna?

Very Cool project and your loading coil is beautiful, thanks for sharing. I love messing with antennas too.

Instead of cutting the wire, you could have actually just folded the wire over multiple times to make it think it was shorter! The end o9f it being folder over doesn't change it's radiation pattern! \

So, how did the other bands do after the modification? Are they still good?

Paul, this is Markus - db9pz - talking to you. We met a few month ago, when you testet you 'QRP'-rig, I was the first station, also QRP, speaking to you, ... ! I enjoyed that QSO very much, ... ! Thanks again, dear Paul. Please take more care of the 'size' of wire and cord! The 'clamps' and the 'closing-keys', will not fit for the wire you need. Too much 'room' in between! And 'solder' alone, can have a 'solid flow', so that it will not fix the wire permanently. It will work and 'flow', milimeter for milimeter, out of the soldered ring... ! A problem that every electrician in the world will know, ... ! Also, why don 't you crimp the fitings for the wire not first, and then solder it for safety reasons? Also , you can make some shrinking-tube, (best with heat-clue inside) over all connetions to 'weather-proof' them. You later told about it in your video. Sorry, ... ! 73/72 de Markus - db9pz (JN39fq - 5km/3miles east of LX))

good job

I would have wrapped kapton tape over the winding. That coil is a nice place for birds to land. Over time the enamel will be gone without any protection. Problem or not, don't know 😀.. 73 OH7WV

For final fine-tuning, NEVER cut a wire, just bend it back.

Ця сіра труба на сонці швидко зруйнується (застосовується в приміщеннях)😢

👍 Good work Paul and thanks for video. I will keep a look out for you on 80m.

👏👏👍

Coil 80uH

Внутри катушки не должен быть металлический предмет, будут потери.

Thank you for the video. Please note, that you have a typo in your video description. 1430 mm equals 1.43m. Vy 73 Markus

Very professional Paul. Great work. 73

Looking at your plot should you not have enough space to put up a 80mtr dipole instead of EFHW which is imho a compromise?

hey Poul, what if you put 2 short wires in the end, like a Y shape.. with diff. lenght.. then perhaps the bandwidth will be wider ? with rgds oz1fjb

This was a great video. Thanks for sharing this with us. 🤙

Paul. I am going to put this antenna together using the 40m EFHW as the starting point (I have limited run distance). Would you please confirm my understanding of the rig? After the 49:1 UnUn, a 19+M wire, then the 110mh loading coil and then about 1.5 M wire, cutting this last wire to length to control SWR. Thanks for your help, N7DKE

Fantastic video...Nice that you left the mistake in... Well done.. M1bsz

sir,what the coil for?

Can you please tell what the coil form is called and what it’s supposed to be used for/

No good -22j minute 25:52

Very well engineered.

Very relaxing video 👍

You do not need another wire if you cut too much, just solder thin wire, end of antenna have extreme low current and maximum voltage. When I trim antenna wire I never cut end of wire just wrap around , no need to cut. So if you need lower frequency just release wire. You already have bunch of wire. But not everybody.

У МЕНЯ ЕСТЬ ЗАКЛАТНА НА Видио . ТРЕХДИАПАЗОННЫЙ ДИПОЛЬ НА 80 / 40 / 20 МЕТРОВ

turn off music you punch

Just once I'd like the meat without the beat... Glitzy crap music.

This is one annoying video.

Gathering material now ! The 49>1 balun transformer works like a charm for sure thanks. KE4TDG. 73.