I really like your relaxed manner of speaking. Your content is very informative while you also share your experience with newer Hams. Thanks for your service!
Nice video. My first wire antenna was an EFHW after decades of yagis and verticals. It was a 10-40 with a 24' counterpoise in a straight horizontal line pulled tight between a cliff and building 65' AGL I'm still amazed at how good it works from 10-80 no ATU needed! Should have made one decades ago. n2eye
Sir, I gave this a try. I had an 80 meter EFHW that did not fit on my lot because my house was in the way. I tried running it off the roof but was blowing circuit breakers in the house at full power. (Not ideal). So, I tried this "trick". Not only did it work PERFECTLY, but I successfully moved the preferred low point in the SWR out of the CW section and squarely in the phone section at 3.9MHz at 1:1.15. Pro tip: When tuning the resonator start long and rather than cutting the wire, simply keep winding the excess around an insulator (I used a bare copper wire for the resonator). The last changes to the resonator were literally centimeters in length and even then I went too far and had to back up. However, the theory and reality are equal. This is absolutely brilliant! Thanks so much.
I built the 80m loading coil. Worked a treat! Here's my build details: Measures 110 uH (B&K Precision 875B LCR meter) 0.8 mm enamel wire 1 - 1/16" (26.6 mm) outer diameter plastic pipe Close wound wire - 129 mm long coil 145 turns Simply adjust the resonator wire length for the desired portion of the 80m band. Thanks Peter 72
Thank you. Some of your tricks have also been used on dipoles in the past. For example using a coil as an RF choke as at higher frequencies and a loading coil at the lower frequency.
I made myself a EFHW style end fed half wave (shortened to approx 23m), including the transformer and a 110uH coil, I am pleased with it because it is indeed multi-band and its relatively easy and cheap to make. I am now making a more durable version for permanent installation. Thanks for this informative video that added to my knowledge on these antennas.
Another great video Peter, first class explanation of chokes and coils. Used to see my students eyes glaze over when I was trying to explain the differences. Thanks for posting. 👍🏻👍🏻👍🏻 73 de M0AZE Mike
I fitted the 80-meter coil today, SWR 1.2 I have it in an inverted V configuration due to a small garden, the center of which goes up the mast. The transformer is fed by 213 coax down the garden where the transformer is bolted to a pole 10 feet off the ground. no counterpoise, no earth. works very well more than pleased.
Hi Peter, I only have a very small garden so mounting it was a problem. I ended up putting the end-fed down the garden in an inverted V configuration, the center of the end-fed is connected to the mast at the house end using a none conductive connecter, I also put a counterpoise from the box 12 inches off the ground. I was very surprised at the signals I was receiving on all bands, I still had the dipole up so I could compare the 2 antennas, and I think the end-fed came out on top, I now need to but the OJV-80K coil or I might even make one. Thank you for the film.
I am a SWL, I made this antenna thanks to instructions. The commercial loading coil OJV-80K was out of stock so I made my own, hoping the turns etc. were right. I wound 76 turns of 20 SWG magnet wire onto a 40mm PVC former, and varnished the coil. The configuration I used was 50 feet horizontal and 17 feet vertical (awkward shape garden) and 2 meters of cable after the coil for the 80 meter part, then to a 49-1 unun. I haven't tried it out yet, because I think the conditions are not so good at the moment, maybe I am wrong, I am only learning all this.
Mike, many of us started with little knowledge but lots of determination. You are right - conditions are very poor at the moment. But from now on will improve - but only gradually! 73 Peter.
This is absolutely brilliant. I am going to build an 80 meter out of a 40 meter antenna using this technique in the next 2 weeks and I'll let you know how it goes.
Thanks for your efforts with these videos. Most helpful. I am lucky enough to have large garden and want to install a dedicated antenna for 80m. I could either install a 40m long flat top efhw or a 1/2 wave dipole with 20m per side. Which do you think would give the best results?
Great video, these are great antennas I sometimes use another trick I use a 80 to 10 efhw I use it on top band with great success I have a dipole connector with a short wire and Croc clip which I simply clip onto wire antenna on transformer ( hot side if dipole connector) I then connect ground side of dipole connector to a ground rod, radials are even better, then undo pl259 feed from transformer plug into dipole connector you now have a quartewave for 160m. This also works a treat for say 66ft wire 40 to 10 as a quartewave for 80m, this us a very simple method if your transformer is easily accessible. Thanks again
Been using 133 ft EFHW for several years. Tuned with a NANOVNA. It is near 1 to 1 on 7.30 mhz. Tuner works to get from 80 to 10 meters. Won't tune 6 m at all. 160 will tune to about 1 to 1.7 SWR but doesn't seem to be effective. Currently at about 12 feet on each end and 8 feet in the center. Covers the whole SE USA from Canada to Florida and west to the Mississippi. I guess it works like a NVIS. Great with my 100 watts. Hope to put up another one at 90 degrees to the first and somewhat higher.
WATSON OJV-80K ordered cheers , the perfect solution , i have a 80 efhw which i have to bend twice to get in the garden , with our garden just under 30 meters long this will fit much better , also enabling me to get it higher , much appreciated
hi Peter i have made a few of these and the 20 mtr half wave coil use a 34uH coil.. the 40mtr wire will use a 104 uH coil, these are great low profile and i have mine running around the garden about 3 mtrs of the ground....great for nvis on 40
with coax losses and transformer losses taken into consideration efhw does work. i get same performance from dipole on 20m rg58 as efhw on 10m rg174. some times the ef will be louder, sometimes more noisy. mine gives great swr daytime but can be poor at night. the transformer is potted in resin btw
Please help me if you can. I do not know the orientation of the actual Antenna by looking at the radiation pattern. Is the antenna going left and right or up and down in the photographs. And are these photographs being viewed from above like a bird looking down onto the pattern or from the side, as if we were standing on the ground, looking at the pattern. Or could you point to some, educational literature so I can begin to understand how to read these radiation patterns. Thank you so much.
Hi Peter, really interesting video again. I have been using an end fed antenna for 40-10 for sometime now with good results. I recently moved the location of the 49:1 TX slightly as was trying to improve the SWR on 20m. I couldn't get the swr below about 1:8 : 1, I know this is ok but there is room for improvement. Whilst experimenting (without me knowing) my four not great radials fell off. From this point onwards my SWR reduced to less than 1:3 : 1 across 40 and 20. I still need an ATU for 15 and 10 as they are about 2:5 :1. So I am confused, do I need to re attached the radials or forget about them ? Also, 80m in now under 3:1 :1 which confuses me further. One thing I noticed you mentioned is that it is not a good idea to have a line isolator at the far end, only by the transceiver. Why is this ? Through experimentation I have ended up with an isolator at both ends ? I suspect this might not be a good idea ? Should I be worried my SWR is better without radials ? Since discovered, removing far end isolator puts SWR back to 1:8 :1 region, maybe SWR being incorrectly affected ? Many thanks. John
@@watersstanton Well the USA still uses it so it's not just an age thing, but UK and all of the rest of the world uses metric these days so I think both is better than one or the other if possible. 73!
The metric measurements are a bit of a no-brainer though. A half wave on 40m will be 20m, a half wave on 20m will be 10m, and a half wave on 17m will be 8.5m. Make it a bit longer and trim for resonance. :-)
Indeed, but my point is that you don't need to go through the calculations as you already know (approximately) the wavelength as that's what the band is called. It's called the 20m band because it has a wavelength of 20m, and thus half a wavelength will be 10m. Approximately, hence starting off a bit longer and cutting for best SWR.
Please I would like to know how a line insulator is made that you use near the TRX? Is it done with the Toroid and thread or instead with rail rings on the Coax cable? Thank you IK7JXE
Hi, I hv a My antennas 40-10, extended to an 80-10. A ground rod was placed beneath the box. From the ground rod, I used an alligator clip and 14 gauge wire, which I ran on the grass, parallel to the antenna wire(134 feet). The difference, especially on 160 and 80, is an s unit or two. I am always being told what a nice signal n audio is coming from the antenna and my 7300. This reflector wire or counterpoise wire, seems to do the trick. I hope others try this on the already, fantastic‘My antennas’ antenna😁. The kicker is: Along with my trustee Mfj-939 tuner and the counterpoise, I work 160 nightly, with good results throughout the northeast from my location in so Connecticut. Just thought u wld like to know. Billy
@@watersstanton If I may ask I always worry about Rf in the house. I have 100 feet of 8x, of which 20 feet are wrapped in a two foot loop, hanging on the tree. Only 3 feet makes it into the house. Is there a way to check for rf? Also, as a precaution, I heard that wrapping 12 turns tightly, around a 2 or 3 inch piece of pvc, usually does the trick?? Any comments are welcomed. Best Billy
Hi Peter. Can you run a inverted L EFHW antenna up the side of a steel pole? I am using a steel pole with my 80m centre feed in a inverted V configuration. I want to set up 80-10m EFHW antenna running up the same steel pole about 5m and then the horizontal for the remanding 15m to a fibreglass pole. So will the steel pole effect the EFHW antenna at all? Thank Bruce NZ
It got me thinking though, obviously if you have a loaded antenna for 14MHz that it wouldn't be as good as a full sized half wave. But then on 18MHz, which would be better, a resonant (trapped) half wave, or a longer antenna, say a half wave on 14MHz, but with a tuner to match it?
Paul Sengupta In theory a trap will make the 20m antenna less efficient, I doubt you would detect a difference in performance if you tested the two antennas back to back. I would recommend a resonant antenna over one that needs an ATU, this trapped design looks like an uncomplicated way to achieve that
After my previous comment I decided to try out the antenna I had put up. I am a SWL, just an interested earwigger that is still learning. I tried this antenna out on my SDR SP1A (trying to get my head around this as well). I tuned around the amateur bands and not getting much at all. Then I tried 17 meters, and after twiddling the SDR I heard an amateur radio chap from the island of Crete on 18.120MHz. I listened for half an hour at 1600 UTC. I don't have hardly a clue about all this. But I heard him say that he was using a 4 element beam and 400watts. Is that maybe the reason I heard him because of his power output. Forgive my ignorance in these matters.
I am a SWL, thanks to Peter's video I made the 67 foot antenna with a loading coil and a 2 meter section for 80 meters with a 49-1 unun and it works good in my small garden. I would like some advice here if possible. My neighbour next door has given me permission if I want to add about another 25 or so feet to the antenna wire after the loading coil going at ninety degrees. Would this help me with my reception at all, and also for receiving some broadcast bands. I get quite a few broadcast bands on the antenna as well as plenty of amateur radio operators. Sorry if this seems a daft question but being a newbie to most of this I need to learn. Thank you in advance.
Hello and thank you for great video. I have a large lot and I like to receive all bands if possible with an EFHW antenna only for receiving (not transmitting) Do I need unun? And what length of long wire do I need to get the most bands and what length of wire after the choke/coil? And approximately how many turns on the coil I live in California and have a hard time receiving DX Thank you 🙏
If you have a 33-34ft EFHW for 20m and you want to use it on 40m, then just bypass the 49:1 and use it as a quarter wavelength monopole (Lo-Z feed point). You'll need a good ground or a counterpoise or something.
Thanks for the video. I successfully made a coil for my 40M EFHW and it worked well across the 80M band. What is the formula for determining how much inductance is needed to go from xM to xM, number of windings, etc for this project?
There is no formula as such . I use cut and try! The coil you have acts as a choke on all bands from 40m up. For 20m upwards, halve the turns. It is roughly proportional.
Interesting comment about the line isolator being at the transceiver as opposed to the antenna feed point. I run line isolators, but have always had them at the feed point. But you are indicating that there is benefit in bringing it indoors to the transceiver? Does it make a difference if the line isolator is at the feed point of the EFHW, but there is a coax ground via use of lightning arrestor between the transceiver and the feed point?
I would not put an isolator ar thefeed point of an EFHW as the coax sheath does benefit ooeration. BUT always use an isolatir at Tx end no matter what else you have at tge feedpoint. The coax shesth will not only exhibit common mode current flow, but also directly pickup radiated RF from the antenna. 73 Peter
Like the other commenters I like your style. The explanation of the loading coil which is also a choke was simple and easy to understand. I'm curious though, I have an EFHW 8010 from "My Antennas" and I would assume that it would work in a similar manner to get me up to the 160 meter band. How well do you think this approach would work?
It will work. I cannot give you the coil dimensions but if you look on Google for the coil size needed for a base loaded 160m mobile antenna, you will be pretty close. Do remember that the bandwidthe on 160m will be quite narrow. 73 Peter.
Just got my General Ham license and have an HF rig, a Kenwood TS-430S and now I need an antenna and an antenna tuner. And I've got 1.7 acres to work with. What is a line isolator??? 73 from K9POW in eastern Tennessee.
Some great ideas in here, I love antenna experimentation, and I will have to try those loading coils. It'll take my mind off the stupid election.. (:-)... Thanks Peter for these great videos..
Thanks for the information, very instructional. Recently moved from a 2 acer yard in South Carolina to a 60x100ft yard in Connecticut ! Trying to figure out what to do. well 73 Leo k1zek k
That should be big enough for a full sized inverted V on 80m (wherever you choose to feed it) if you can get the middle up high enough. Or you could have a horizontal antenna with the last 33ft (133ft total) going off at 90 degrees.
I have a 132ft EFHW with a 49:1 unun as a sloper. Far end about 24ft up. Feedpoint and unun about 10ft up. Planning on raising the far end. What do you recommend for feedpoint height? BTW, I have a very long counterpoise wire running a few feet above ground level and a Palomar common mode choke near my shack. No RF in shack even with 1KW. Alpha 78 in bandpass mode auto tunes to low swr on 80, 40, 20. IC 7300 with IT 100 tunes 80-6 with less than 1.5:1. Appears to radiate well. Mel, K2JWD
Thanks for video and thanks for earlier answer. I am thinking about making the 42' horizontal and the 25' verticle with the 49-1 unun at the bottom to fit my awkward space. Would it be OK to have a 50' horizontal section and a 17' or so verticle section instead of the 42'-25'.
Thanks Peter. A good basic guide. I've tried the 40/20m version with good results. On 40m it's only slightly down on a full sized version. Main thing to watch is its bandwidth on 40m is quite narrow - you'll have to decide whether you want to optimise it for CW or the SSB end. My video demonstrating it is here: ua-cam.com/video/TV3Cj2J3T20/v-deo.html
I have recently purchased an end fed antenna. I wish to use it mainly for 40 meters. The length of the antenna is 41ft , which is roughly a quarter wave length at 40 meters. Would it make much difference if the wire length was increased to around 66 ft, so it would then be a half wave at 40 meters?
Thank you Peter. Ive just bought another EFHW (Vibroplex) for camping in our motorhome. I was going to stick the line isolator outside the van just to keep the RF outside and stop inference with the TV as is has in the past with other antennas. Do you have any thoughts on this?
Thanks for the video. With regards to use of an earth, I have a commercial end fed for 40m from Moonraker which has a built in earth. I built a crystal radio receiver and attached it to the antenna. I get good reception when the earth is used but it immediately vanishes when I disconnect the earth. Reception is on the am broadcast band(Absolute Radio which swamps everything else) which I appreciate is completely the wrong band for the antenna but was wondering what your thoughts are on this.
I built a receiving 27MgHz at Kenwood training Course in the 80's.using a wire Earthed to allow resonance if I remember correctly? This was a small circuit design for SOE in WWII ! Hilary Clayton-Smith got me on the course and Kenwood trainers were showing us a non-detectable device.
Thanks for video. I am a SWL and listen as far as I possibly can around the bands. I have an awkward shaped small garden for a start. I have in the past had random wire antennas strung up until I was blue in the face. I am not too good on theory but fine with construction and soldering. I can just about get about 90 feet of cable about 20 feet in the air in a right angle configuration. One leg from sort of north south the other leg roughly east west. I have a verticle antenna and a magnetic loop antenna at the moment but dying to get some more cable up. Would this video be OK for RX only. Thanks again.
yes the same applies to reception. But this antenna would be at its best on the ham bands. it will work for broadcast etc., but with reduced signal strength. As always - try it! 73 Peter
I have 2 questions: #1 - Can you use both the 40m loading coil and the 80m loading coil together in 1 antenna? #2 - What would be the effect if you hung this roughly 50' wire in an inverted-V at an 18' center height?
I have one of these end-fed antennas on its way. thank you for this information if I am successful in getting it to work ok I will invest in an 80-meter coil.
Peter, great video as always. When you mentioned a 'line isolator', I assume you meant an RF choke. I have tested a high quality commercial choke at both the EFHW antenna feedpoint (20 ft above ground) and at the transceiver on the other end of my 50 ft coax. The results (at least as far as my SWR meter is concerned) are much better at the antenna feedpoint which prevents RF radiation on the coax. Why do you recommend the RF choke at the transceiver and not the antenna feedpoint? Greg, 73 KJ6ER Silicon Valley
Hi. The VSWR should not change but most VSWR meters are sensitive to their position on the feeder. Placing the isolator at the feed point allows RF to be induced back into the coax feeder. it also allows RF interference to flow down the coax. Peter
I've seen advice which says that the choke should be at least two metres from the transformer along the feedline, but I can't remember what the reasoning was. Others have a combined transformer and choke in one box. I was going to try this for portable use, but putting them so close together seems a bit dubious to me.
@@paulsengupta971 I've read that if you don't ground the antenna, same point as coax shield, then you must NOT "choke" at the feedpoint. If you supply a ground then you can choke the feedpoint.. As I understand there has to be a "return" path, either the outer coax shield or a ground. The EFHW Facebook page is prolific with all type of this kind of information, "caveat emptor".. Regards wb7ond
Thanx alot Sir for such a brilliant video, I need to ask that, what if I install EFHW in a normal L configuration ( not Inv L) in your opinion how good it will be with DXing point of view, as a matter of fact I'm planning to install it in normal L configuration with about 35 ft vertical and rest of the length as horizontal..thanx
@@watersstanton Antenna will be installed at around 20 ft of height above the concrete roof of my house, but the horizontal section would be about 8 ft further above the roof....thanx for the early reply..will share the results with you.
I would like to purchase an 80 meter loading coil for my 40-10 end fed antenna. I went on the Waters Station website but the OJV-80K coil is not available there. Can you provide an alternate source? Thank you.
I purchased the loading coil and my order confirmation (P.O. #1000019243 L23.30 GBP) came back which included L6.67 GBP charge for shipping and handling. I was then contacted by your Nola Knowles that an additional L41 charge was necessary for international shipping. So I am to pay L47.67 to pay for shipping an L16.63 loading coil??? This is ridiculous. Can't you send it here a cheaper way? Carl W6CG
I am due to show foundation students how to tune a long wire 1/2 wave for 40 and use a loading coil for 80M. You have saved me a lot of words. Could we have more information about the line isolator. 73 G8AXA
I use a Mfj. 10-80 half wave end fed antenna. The lowest I can get my swr to when using my Mfj 998 auto tuner is about 1.6 to 1.8 on 75 meters. No way my Icom 7300 can operate with its internal 3 to 1 tuner. So I could not operate without a tuner.
Hi i have a small garden but have put up a 80-10 efhw at 140ft long but zig zagged it up my garden.....was wondering if I cut it to 66ft and bought one of your coils would it work better or worse as less wire?? Just means I could probably get a 66ft alot higher?? Many thanks
It’s worth avoiding coils if at all possible. Do you have any height that you can use? Could you start or end the antenna with a vertical section? A 10m pole would give you 30+ wire straight up. You might get more comments on here, but feel free to message me - my email address is on QRZ.com Cheers, Matt M0PTO
@@tincanblower thanks matt .at the moment it starts with around 35ft vertical,then goes 33ft horizontal,then back to the house horizontal 33ft and then slopes down to the fence so in theory its in the shape of an N .Tunes on 80-10m with no external tuner which is a good thing n have worked usa,trinidad,Canada,Europe etc but we always want better
Andy Bronson M7xtt performance on 80m will be down as your 66ft plus coil will become a compromise on 80. This is the antenna I use but the good news is because signals on 80m in the evenings are generally so good you won’t see a big difference. Don’t expect great results on the higher bands until the new sunspot cycle really gets underway.
Thanks Peter, and (as always) a nice informal and technically sound analysis of EFLW antennas - I wish I could stop by and sit there with you to ragchew antennas! :- While I love (the idea of) experimenting with wire antennas and previously have done a ton of that both in the UK and here in Canada, I find that these days (btw, we are in the same age bracket) I seem to have LESS TIME to experiment and just want to get out to the POTA or SOTA sites and operate. Having said that, I hope (hint, hint) that you will 'kit' some EFLW antenna packages via W&S with a shipping option to Canada? 73
Almost true about not needed an antenna tuner. You won't get 1:1 swr across all bands, but should be less than 3:1 at worst. Is that loading coil available for 160 meters (IE: to ad 160 to an 80m EHW antenna)?
A 9:1 should be used (with a tuner) for a "random" (non half wave) length of wire. A 49:1 should be used for a half wave (and doesn't need a tuner). If you have a standing (half) wave on a piece of wire, the impedance will vary from around 72 ohms at the centre (think centre fed dipole) to two to four thousand ohms at the end. Between these, the impedance will vary as you go along the wire. Feeding at the 2/3 : 1/3 point with a 4:1 balun is reasonably popular to feed coax. If you have a half wave fed at the end, you want to bring the few thousand ohms down to coax impedance hence a 49:1 transformer (or a matching section as in the Zepp or J-pole both of which are just end fed half waves). If the wire isn't a half wave, you're effectively feeding it at a random point on the wave where the impedance could be perhaps 200-1500 ohms. A 9:1 will bring it down to the point where a tuner can compensate for the rest. There are quite well defined "random" lengths to use in order to avoid the feed point being too close to the centre or the end of the wave on all the bands it's designed for, and hence avoiding the impedance being too high or too low.
I'm a new Ham and have learned more about antenna's from you than from all the study and reading. Thank you.
Your knowledge and training is so valuable to me. This video is a masterpiece. And I enjoy your presentation style.
I really like your relaxed manner of speaking. Your content is very informative while you also share your experience with newer Hams. Thanks for your service!
The Charles Dowding of Amateur Radio! Awesome delivery ole chap!
Nice video. My first wire antenna was an EFHW after decades of yagis and verticals. It was a 10-40 with a 24' counterpoise in a straight horizontal line pulled tight between a cliff and building 65' AGL I'm still amazed at how good it works from 10-80 no ATU needed! Should have made one decades ago. n2eye
It’s a common experience! Good to hear from you. 73 Peter.
Great video👍 Half the fun of ham radio is playing with antennas and trying to make the strangest of configurations work❗️
Sir, I gave this a try. I had an 80 meter EFHW that did not fit on my lot because my house was in the way. I tried running it off the roof but was blowing circuit breakers in the house at full power. (Not ideal). So, I tried this "trick". Not only did it work PERFECTLY, but I successfully moved the preferred low point in the SWR out of the CW section and squarely in the phone section at 3.9MHz at 1:1.15.
Pro tip: When tuning the resonator start long and rather than cutting the wire, simply keep winding the excess around an insulator (I used a bare copper wire for the resonator). The last changes to the resonator were literally centimeters in length and even then I went too far and had to back up. However, the theory and reality are equal. This is absolutely brilliant!
Thanks so much.
I built the 80m loading coil. Worked a treat! Here's my build details:
Measures 110 uH (B&K Precision 875B LCR meter)
0.8 mm enamel wire
1 - 1/16" (26.6 mm) outer diameter plastic pipe
Close wound wire - 129 mm long coil
145 turns
Simply adjust the resonator wire length for the desired portion of the 80m band.
Thanks Peter
72
Thank you. Some of your tricks have also been used on dipoles in the past. For example using a coil as an RF choke as at higher frequencies and a loading coil at the lower frequency.
Hi Donald. Yes you are correct. We were using this method back in the 1960s. 73s Peter
I made myself a EFHW style end fed half wave (shortened to approx 23m), including the transformer and a 110uH coil, I am pleased with it because it is indeed multi-band and its relatively easy and cheap to make. I am now making a more durable version for permanent installation. Thanks for this informative video that added to my knowledge on these antennas.
High there. Glad you getting good results. 73 Peter
beautiful garden and helpful video. Thanks!
Absolutely great info that adds flexibility to EFHW aerial configurations.
Many thanks. 73 Peter
Another very educational and helpful video, thank you OM Peter!
Another great video Peter, first class explanation of chokes and coils. Used to see my students eyes glaze over when I was trying to explain the differences. Thanks for posting. 👍🏻👍🏻👍🏻 73 de M0AZE Mike
Thanks Mike
I fitted the 80-meter coil today, SWR 1.2 I have it in an inverted V configuration due to a small garden, the center of which goes up the mast. The transformer is fed by 213 coax down the garden where the transformer is bolted to a pole 10 feet off the ground. no counterpoise, no earth. works very well more than pleased.
Thanks Brian. Looking good. Have fun. Peter.
Hi Peter, I only have a very small garden so mounting it was a problem. I ended up putting the end-fed down the garden in an inverted V configuration, the center of the end-fed is connected to the mast at the house end using a none conductive connecter, I also put a counterpoise from the box 12 inches off the ground. I was very surprised at the signals I was receiving on all bands, I still had the dipole up so I could compare the 2 antennas, and I think the end-fed came out on top, I now need to but the OJV-80K coil or I might even make one. Thank you for the film.
Hi Brian. Glad it is working out. Remeber there are extra lobes on 20m and above so a little bit of gain in the dire tion of the lobes. 73 Peter
@@watersstanton Thank you for your reply.
@@watersstanton when will you have the 80-meter OJV-80K coils in stock I wonder :)
I am a SWL, I made this antenna thanks to instructions. The commercial loading coil OJV-80K was out of stock so I made my own, hoping the turns etc. were right. I wound 76 turns of 20 SWG magnet wire onto a 40mm PVC former, and varnished the coil. The configuration I used was 50 feet horizontal and 17 feet vertical (awkward shape garden) and 2 meters of cable after the coil for the 80 meter part, then to a 49-1 unun. I haven't tried it out yet, because I think the conditions are not so good at the moment, maybe I am wrong, I am only learning all this.
Mike, many of us started with little knowledge but lots of determination. You are right - conditions are very poor at the moment. But from now on will improve - but only gradually! 73 Peter.
This is absolutely brilliant. I am going to build an 80 meter out of a 40 meter antenna using this technique in the next 2 weeks and I'll let you know how it goes.
Many thanks Woody. 73 Peter
Thanks for your efforts with these videos. Most helpful. I am lucky enough to have large garden and want to install a dedicated antenna for 80m. I could either install a 40m long flat top efhw or a 1/2 wave dipole with 20m per side. Which do you think would give the best results?
Great video, these are great antennas I sometimes use another trick I use a 80 to 10 efhw I use it on top band with great success I have a dipole connector with a short wire and Croc clip which I simply clip onto wire antenna on transformer ( hot side if dipole connector) I then connect ground side of dipole connector to a ground rod, radials are even better, then undo pl259 feed from transformer plug into dipole connector you now have a quartewave for 160m. This also works a treat for say 66ft wire 40 to 10 as a quartewave for 80m, this us a very simple method if your transformer is easily accessible. Thanks again
Hi Nigel very interesting. I am sure others will read this as well. All the best. Peter.
Been using 133 ft EFHW for several years. Tuned with a NANOVNA. It is near 1 to 1 on 7.30 mhz. Tuner works to get from 80 to 10 meters. Won't tune 6 m at all. 160 will tune to about 1 to 1.7 SWR but doesn't seem to be effective. Currently at about 12 feet on each end and 8 feet in the center. Covers the whole SE USA from Canada to Florida and west to the Mississippi. I guess it works like a NVIS.
Great with my 100 watts.
Hope to put up another one at 90 degrees to the first and somewhat higher.
Thank you very much for your informative video with clear explanations. I have learned a lot!
WATSON OJV-80K ordered cheers , the perfect solution , i have a 80 efhw which i have to bend twice to get in the garden , with our garden just under 30 meters long this will fit much better , also enabling me to get it higher , much appreciated
Great news. 73 Peter
Yet another excellent video, many thanks Peter
Many thanks
hi Peter i have made a few of these and the 20 mtr half wave coil use a 34uH coil.. the 40mtr wire will use a 104 uH coil, these are great low profile and i have mine running around the garden about 3 mtrs of the ground....great for nvis on 40
Thanks for the info! 73 Peter
with coax losses and transformer losses taken into consideration efhw does work. i get same performance from dipole on 20m rg58 as efhw on 10m rg174. some times the ef will be louder, sometimes more noisy. mine gives great swr daytime but can be poor at night. the transformer is potted in resin btw
Antenna - Tips and Tricks are always welcome and put to good use. Great video and thanks for sharing! Dave - KU9L
This is brilliant. Thanks for sharing your experience.
My pleasure! Peter
That was so interesting and informative one! Thanks and 73.
Many thanks. Peter
Please help me if you can. I do not know the orientation of the actual Antenna by looking at the radiation pattern. Is the antenna going left and right or up and down in the photographs. And are these photographs being viewed from above like a bird looking down onto the pattern or from the side, as if we were standing on the ground, looking at the pattern. Or could you point to some, educational literature so I can begin to understand how to read these radiation patterns. Thank you so much.
Nice video! I don’t use a line isolator instead I ground the outer shield of the coax before it enters the shack
Good advice but with upstairs shacks the earth point is often well above true RF earth. 73 Peter
Excellent video I really enjoy the 40 Meter Band on SSB KC9QVE Marion,Indiana
Thanks Tony
Hi Peter, really interesting video again. I have been using an end fed antenna for 40-10 for sometime now with good results. I recently moved the location of the 49:1 TX slightly as was trying to improve the SWR on 20m. I couldn't get the swr below about 1:8 : 1, I know this is ok but there is room for improvement. Whilst experimenting (without me knowing) my four not great radials fell off. From this point onwards my SWR reduced to less than 1:3 : 1 across 40 and 20. I still need an ATU for 15 and 10 as they are about 2:5 :1. So I am confused, do I need to re attached the radials or forget about them ? Also, 80m in now under 3:1 :1 which confuses me further. One thing I noticed you mentioned is that it is not a good idea to have a line isolator at the far end, only by the transceiver. Why is this ? Through experimentation I have ended up with an isolator at both ends ? I suspect this might not be a good idea ? Should I be worried my SWR is better without radials ?
Since discovered, removing far end isolator puts SWR back to 1:8 :1 region, maybe SWR being incorrectly affected ?
Many thanks. John
Like your videos. Music on this one was terrific. Uh, good tech too!
Thanks 👍
Enjoyed ur end fed videos and Peter is a great name:)
Many thanks
Elegant and proper like Master Richie Rich's butler Cadbury.
Thanks enjoyed the video! 😀
Many thanks. 73 Peter
Thanks very much great info, but I'd love it if you'd use Imperial and Metric measurements in your videos.
hi there. It’s an age thing! Will try.
@@watersstanton Well the USA still uses it so it's not just an age thing, but UK and all of the rest of the world uses metric these days so I think both is better than one or the other if possible. 73!
The metric measurements are a bit of a no-brainer though. A half wave on 40m will be 20m, a half wave on 20m will be 10m, and a half wave on 17m will be 8.5m. Make it a bit longer and trim for resonance. :-)
@@paulsengupta971 I know how to calculate wavelength in metric that wasn't the point. (300/Freq in MHz then multiple by Velocity factor)...
Indeed, but my point is that you don't need to go through the calculations as you already know (approximately) the wavelength as that's what the band is called. It's called the 20m band because it has a wavelength of 20m, and thus half a wavelength will be 10m. Approximately, hence starting off a bit longer and cutting for best SWR.
Please I would like to know how a line insulator is made that you use near the TRX? Is it done with the Toroid and thread or instead with rail rings on the Coax cable? Thank you IK7JXE
Hi,
I hv a My antennas 40-10, extended to an 80-10. A ground rod was placed beneath the box. From the ground rod, I used an alligator clip and 14 gauge wire, which I ran on the grass, parallel to the antenna wire(134 feet). The difference, especially on 160 and 80, is an s unit or two. I am always being told what a nice signal n audio is coming from the antenna and my 7300.
This reflector wire or counterpoise wire, seems to do the trick. I hope others try this on the already, fantastic‘My antennas’ antenna😁.
The kicker is: Along with my trustee Mfj-939 tuner and the counterpoise, I work 160 nightly, with good results throughout the northeast from my location in so Connecticut.
Just thought u wld like to know.
Billy
Many thanks Billy. I am sure others will be interested in your results.
@@watersstanton Thanku for the quick reply
@@watersstanton
If I may ask
I always worry about Rf in the house. I have 100 feet of 8x, of which 20 feet are wrapped in a two foot loop, hanging on the tree. Only 3 feet makes it into the house.
Is there a way to check for rf?
Also, as a precaution, I heard that wrapping 12 turns tightly, around a 2 or 3 inch piece of pvc, usually does the trick??
Any comments are welcomed.
Best
Billy
@@watersstanton Could check my second question and reply when you have a chance. Thanku. William
Should I attach a counterpoise wire at the unun? if dso how many feet long for 40 meters?
Not needed. Coax feeder outer sheath does the job.
Man do you live in a beautiful place !
Hi Peter. Can you run a inverted L EFHW antenna up the side of a steel pole? I am using a steel pole with my 80m centre feed in a inverted V configuration. I want to set up 80-10m EFHW antenna running up the same steel pole about 5m and then the horizontal for the remanding 15m to a fibreglass pole.
So will the steel pole effect the EFHW antenna at all?
Thank Bruce NZ
Great video, I haven't seen the option to add a 18Mhz trap to give dual band coverage. Kinda makes sense - thanks for sharing
It got me thinking though, obviously if you have a loaded antenna for 14MHz that it wouldn't be as good as a full sized half wave. But then on 18MHz, which would be better, a resonant (trapped) half wave, or a longer antenna, say a half wave on 14MHz, but with a tuner to match it?
Paul Sengupta In theory a trap will make the 20m antenna less efficient, I doubt you would detect a difference in performance if you tested the two antennas back to back. I would recommend a resonant antenna over one that needs an ATU, this trapped design looks like an uncomplicated way to achieve that
Thanks guys
The light at around 6:00 is good for horror movies :P
A new career opportunity!
Good advice Pete 👍
Thanks 👍
After my previous comment I decided to try out the antenna I had put up. I am a SWL, just an interested earwigger that is still learning. I tried this antenna out on my SDR SP1A (trying to get my head around this as well). I tuned around the amateur bands and not getting much at all. Then I tried 17 meters, and after twiddling the SDR I heard an amateur radio chap from the island of Crete on 18.120MHz. I listened for half an hour at 1600 UTC. I don't have hardly a clue about all this. But I heard him say that he was using a 4 element beam and 400watts. Is that maybe the reason I heard him because of his power output. Forgive my ignorance in these matters.
OK Mike. Stick at it. Conditions are poor at the moment. 73 Peter
I am a SWL, thanks to Peter's video I made the 67 foot antenna with a loading coil and a 2 meter section for 80 meters with a 49-1 unun and it works good in my small garden. I would like some advice here if possible. My neighbour next door has given me permission if I want to add about another 25 or so feet to the antenna wire after the loading coil going at ninety degrees. Would this help me with my reception at all, and also for receiving some broadcast bands. I get quite a few broadcast bands on the antenna as well as plenty of amateur radio operators. Sorry if this seems a daft question but being a newbie to most of this I need to learn. Thank you in advance.
Hi Mike. Adding extra wire will actually reduce performance on 80m. It will lower the resonance to around 2.9MHz which is not what you want. 73 Peter
@@watersstanton Thanks for advice Peter.
Hello and thank you for great video. I have a large lot and I like to receive all bands if possible with an EFHW antenna only for receiving (not transmitting) Do I need unun? And what length of long wire do I need to get the most bands and what length of wire after the choke/coil? And approximately how many turns on the coil
I live in California and have a hard time receiving DX Thank you 🙏
If you have a 33-34ft EFHW for 20m and you want to use it on 40m, then just bypass the 49:1 and use it as a quarter wavelength monopole (Lo-Z feed point). You'll need a good ground or a counterpoise or something.
And a means of switching.
Some great ideas here, thanks!
Glad you like them! 73 Peter
Thanks for the video. I successfully made a coil for my 40M EFHW and it worked well across the 80M band. What is the formula for determining how much inductance is needed to go from xM to xM, number of windings, etc for this project?
There is no formula as such . I use cut and try! The coil you have acts as a choke on all bands from 40m up. For 20m upwards, halve the turns. It is roughly proportional.
@@watersstanton Does it matter if the coil windings are next to each other or can there be 1 or 2 mm spacing between wires? Thanks again.
Can I add 131.2 feet wire ?
Interesting comment about the line isolator being at the transceiver as opposed to the antenna feed point. I run line isolators, but have always had them at the feed point. But you are indicating that there is benefit in bringing it indoors to the transceiver?
Does it make a difference if the line isolator is at the feed point of the EFHW, but there is a coax ground via use of lightning arrestor between the transceiver and the feed point?
I would not put an isolator ar thefeed point of an EFHW as the coax sheath does benefit ooeration. BUT always use an isolatir at Tx end no matter what else you have at tge feedpoint. The coax shesth will not only exhibit common mode current flow, but also directly pickup radiated RF from the antenna. 73 Peter
@@watersstanton ...thanks for the quick response. Moved them into the shack today. Resealed my antenna feed point outside. Thanks again
link to the OJV-80K please?
Hi Peter I managed to order the 80-meter coil today, :)
OK Brian - soon be on 80m. 73 Peter
A pipe smoker I see. Out of curiosity, what blend and flavors do you prefer? I'm wanting to try something new.
As a portable qrp operator perfect stuff thanks 👍👍👍 73’s Phil M6dnu
Many thanks Phil.
Like the other commenters I like your style. The explanation of the loading coil which is also a choke was simple and easy to understand. I'm curious though, I have an EFHW 8010 from "My Antennas" and I would assume that it would work in a similar manner to get me up to the 160 meter band. How well do you think this approach would work?
It will work. I cannot give you the coil dimensions but if you look on Google for the coil size needed for a base loaded 160m mobile antenna, you will be pretty close. Do remember that the bandwidthe on 160m will be quite narrow. 73 Peter.
Just got my General Ham license and have an HF rig, a Kenwood TS-430S and now I need an antenna and an antenna tuner. And I've got 1.7 acres to work with. What is a line isolator??? 73 from K9POW in eastern Tennessee.
Check this video channel. I did a video on it. 73 Peter.
Some great ideas in here, I love antenna experimentation, and I will have to try those loading coils. It'll take my mind off the stupid election.. (:-)... Thanks Peter for these great videos..
Many thanks. 73 Peter
Thanks for the information, very instructional. Recently moved from a 2 acer yard in South Carolina to a 60x100ft yard in Connecticut ! Trying to figure out what to do. well 73 Leo k1zek k
Still plenty of room by our standards! 73 Peter
That's huge by British garden size , I wish I had that size garden .
That should be big enough for a full sized inverted V on 80m (wherever you choose to feed it) if you can get the middle up high enough. Or you could have a horizontal antenna with the last 33ft (133ft total) going off at 90 degrees.
I have a 132ft EFHW with a 49:1 unun as a sloper. Far end about 24ft up. Feedpoint and unun about 10ft up. Planning on raising the far end. What do you recommend for feedpoint height? BTW, I have a very long counterpoise wire running a few feet above ground level and a Palomar common mode choke near my shack. No RF in shack even with 1KW. Alpha 78 in bandpass mode auto tunes to low swr on 80, 40, 20. IC 7300 with IT 100 tunes 80-6 with less than 1.5:1. Appears to radiate well. Mel, K2JWD
Great video peter. I'm wondering, can the 40m to 80m coil concept be used for 80m 134ft wire to a coil and a short piece of wire to 160m? Thank you.
Thanks for video and thanks for earlier answer. I am thinking about making the 42' horizontal and the 25' verticle with the 49-1 unun at the bottom to fit my awkward space. Would it be OK to have a 50' horizontal section and a 17' or so verticle section instead of the 42'-25'.
You wouldn't notice any difference really. The radiation pattern may change a little on 15m and 10m but not the efficiency. Go for it! Peter.
@@watersstanton Thanks for that Peter.
Thanks Peter. A good basic guide. I've tried the 40/20m version with good results. On 40m it's only slightly down on a full sized version. Main thing to watch is its bandwidth on 40m is quite narrow - you'll have to decide whether you want to optimise it for CW or the SSB end. My video demonstrating it is here: ua-cam.com/video/TV3Cj2J3T20/v-deo.html
I have recently purchased an end fed antenna. I wish to use it mainly for 40 meters. The length of the antenna is 41ft , which is roughly a quarter wave length at 40 meters.
Would it make much difference if the wire length was increased to around 66 ft, so it would then be a half wave at 40 meters?
If it uses a 9:1 unun then yes but avoid a half wave kength. Go for around 50ft or 80ft.
@@watersstanton Thanks. It has a 9:1 Unun. Will the current length of 41 ft still be ok?
Should I worry about coils and 49:1 baluns in making a receiving end-fed antenna?
Coil no but 49:1 yes. 63 Peter
Thank you Peter. Ive just bought another EFHW (Vibroplex) for camping in our motorhome. I was going to stick the line isolator outside the van just to keep the RF outside and stop inference with the TV as is has in the past with other antennas. Do you have any thoughts on this?
OK. Enjoy the motorhome operation. Peter
Very informative - would it be ok to use the choke to get a shortened half wave at 40m and then add a second choke to add the 80m band as well?
Yes it works but tuning on the lowest band is always quite sharp. 73 Peter
@@watersstantonMany thanks for coming back to me. Yes, I suppose that makes sense. With the combined loading coils.
I have one of the MyAntenna 8010, I replaced the wire with 24AWG which is stealth.
Nice
Thank you!
Thanks for the video. With regards to use of an earth, I have a commercial end fed for 40m from Moonraker which has a built in earth. I built a crystal radio receiver and attached it to the antenna. I get good reception when the earth is used but it immediately vanishes when I disconnect the earth. Reception is on the am broadcast band(Absolute Radio which swamps everything else) which I appreciate is completely the wrong band for the antenna but was wondering what your thoughts are on this.
I built a receiving 27MgHz at Kenwood training Course in the 80's.using a wire Earthed to allow resonance if I remember correctly? This was a small circuit design for SOE in WWII ! Hilary Clayton-Smith got me on the course and Kenwood trainers were showing us a non-detectable device.
Thanks for video. I am a SWL and listen as far as I possibly can around the bands. I have an awkward shaped small garden for a start. I have in the past had random wire antennas strung up until I was blue in the face. I am not too good on theory but fine with construction and soldering. I can just about get about 90 feet of cable about 20 feet in the air in a right angle configuration. One leg from sort of north south the other leg roughly east west. I have a verticle antenna and a magnetic loop antenna at the moment but dying to get some more cable up. Would this video be OK for RX only. Thanks again.
yes the same applies to reception. But this antenna would be at its best on the ham bands. it will work for broadcast etc., but with reduced signal strength. As always - try it! 73 Peter
@@watersstanton Thanks for promp reply. I listen to the ham band quite a lot so I will try it, thanks again.
The loading coil is it similar to a wave trap?
I have 2 questions: #1 - Can you use both the 40m loading coil and the 80m loading coil together in 1 antenna? #2 - What would be the effect if you hung this roughly 50' wire in an inverted-V at an 18' center height?
No the two coils in series are very tricky to adjust. An inverted V is fine provided it is resonant.
I have one of these end-fed antennas on its way. thank you for this information if I am successful in getting it to work ok I will invest in an 80-meter coil.
OK Brian
Thank you, sir. Regards.
Peter, great video as always. When you mentioned a 'line isolator', I assume you meant an RF choke. I have tested a high quality commercial choke at both the EFHW antenna feedpoint (20 ft above ground) and at the transceiver on the other end of my 50 ft coax. The results (at least as far as my SWR meter is concerned) are much better at the antenna feedpoint which prevents RF radiation on the coax. Why do you recommend the RF choke at the transceiver and not the antenna feedpoint? Greg, 73 KJ6ER Silicon Valley
Hi. The VSWR should not change but most VSWR meters are sensitive to their position on the feeder. Placing the isolator at the feed point allows RF to be induced back into the coax feeder. it also allows RF interference to flow down the coax. Peter
I've seen advice which says that the choke should be at least two metres from the transformer along the feedline, but I can't remember what the reasoning was. Others have a combined transformer and choke in one box. I was going to try this for portable use, but putting them so close together seems a bit dubious to me.
@@paulsengupta971 I've read that if you don't ground the antenna, same point as coax shield, then you must NOT "choke" at the feedpoint. If you supply a ground then you can choke the feedpoint.. As I understand there has to be a "return" path, either the outer coax shield or a ground. The EFHW Facebook page is prolific with all type of this kind of information, "caveat emptor".. Regards wb7ond
Thanx alot Sir for such a brilliant video, I need to ask that, what if I install EFHW in a normal L configuration ( not Inv L) in your opinion how good it will be with DXing point of view, as a matter of fact I'm planning to install it in normal L configuration with about 35 ft vertical and rest of the length as horizontal..thanx
Interesting! if the horizontal length is well above ground - say at least 10ft then the results would interest me. Try it.
@@watersstanton Antenna will be installed at around 20 ft of height above the concrete roof of my house, but the horizontal section would be about 8 ft further above the roof....thanx for the early reply..will share the results with you.
160 resonator? Mine set up is 134' AWG13 wire, 30' coax, and 49:1. Ok on 40, 20, 17, 12 and some 10. Bad SWR 6 on 80 and worst in 160. Thanks.
Thanks for info. 73 Peter
I would like to purchase an 80 meter loading coil for my 40-10 end fed antenna. I went on the Waters Station website but the OJV-80K coil is not available there. Can you provide an alternate source? Thank you.
We are waiting new stock. Call Sales 01702 206835.
@@watersstanton Thank you. It is now in stock and I ordered it today.
I purchased the loading coil and my order confirmation (P.O. #1000019243 L23.30 GBP) came back which included L6.67 GBP charge for shipping and handling. I was then contacted by your Nola Knowles that an additional L41 charge was necessary for international shipping. So I am to pay L47.67 to pay for shipping an L16.63 loading coil??? This is ridiculous. Can't you send it here a cheaper way?
Carl W6CG
I am due to show foundation students how to tune a long wire 1/2 wave for 40 and use a loading coil for 80M. You have saved me a lot of words. Could we have more information about the line isolator. 73 G8AXA
OK will try and put something together.Peter
Great video
Thanks!
Hi. I am doing an EFHF 20m long. Can I use the 80m resonator going down vertically to make an inverted L? Thanks
Yes yiu can
I use a Mfj. 10-80 half wave end fed antenna. The lowest I can get my swr to when using my Mfj 998 auto tuner is about 1.6 to 1.8 on 75 meters. No way my Icom 7300 can operate with its internal 3 to 1 tuner. So I could not operate without a tuner.
Thanks for sharing. 73 Peter
Hello from Kansas USA! Well done and thanks! KB0OET
Hello there! Great hear from you. 73 Peter
Great Info, thanks.
Many thanks
Hi i have a small garden but have put up a 80-10 efhw at 140ft long but zig zagged it up my garden.....was wondering if I cut it to 66ft and bought one of your coils would it work better or worse as less wire?? Just means I could probably get a 66ft alot higher?? Many thanks
It’s worth avoiding coils if at all possible.
Do you have any height that you can use?
Could you start or end the antenna with a vertical section? A 10m pole would give you 30+ wire straight up.
You might get more comments on here, but feel free to message me - my email address is on QRZ.com
Cheers,
Matt M0PTO
@@tincanblower thanks matt .at the moment it starts with around 35ft vertical,then goes 33ft horizontal,then back to the house horizontal 33ft and then slopes down to the fence so in theory its in the shape of an N .Tunes on 80-10m with no external tuner which is a good thing n have worked usa,trinidad,Canada,Europe etc but we always want better
Andy Bronson M7xtt performance on 80m will be down as your 66ft plus coil will become a compromise on 80. This is the antenna I use but the good news is because signals on 80m in the evenings are generally so good you won’t see a big difference. Don’t expect great results on the higher bands until the new sunspot cycle really gets underway.
Hi Andy - hope the advice. from readers has helped you. In fact your zig zag would deem to be working quite well.
Thanks Peter, and (as always) a nice informal and technically sound analysis of EFLW antennas - I wish I could stop by and sit there with you to ragchew antennas! :-
While I love (the idea of) experimenting with wire antennas and previously have done a ton of that both in the UK and here in Canada, I find that these days (btw, we are in the same age bracket) I seem to have LESS TIME to experiment and just want to get out to the POTA or SOTA sites and operate. Having said that, I hope (hint, hint) that you will 'kit' some EFLW antenna packages via W&S with a shipping option to Canada? 73
I skipped the loading coil because the antenna should either resonate on 20/40 m or 15/30 m.
Thanks you Peter. Very helpful and interesting video. Mike G7PTV.
Many thanks Michael
Almost true about not needed an antenna tuner. You won't get 1:1 swr across all bands, but should be less than 3:1 at worst.
Is that loading coil available for 160 meters (IE: to ad 160 to an 80m EHW antenna)?
Normally better than 2:1.
@@watersstanton Under ideal conditions. My 80 meter EFHW shows near 3:1 on some bands. Still within range of rigs antenna tuner though.
Thank You
Which Line Isolator Do You Use?
A ferrite core with type 43 mix.
Whats the difference between 9:1 vs 49:1
A 9:1 should be used (with a tuner) for a "random" (non half wave) length of wire. A 49:1 should be used for a half wave (and doesn't need a tuner). If you have a standing (half) wave on a piece of wire, the impedance will vary from around 72 ohms at the centre (think centre fed dipole) to two to four thousand ohms at the end. Between these, the impedance will vary as you go along the wire.
Feeding at the 2/3 : 1/3 point with a 4:1 balun is reasonably popular to feed coax. If you have a half wave fed at the end, you want to bring the few thousand ohms down to coax impedance hence a 49:1 transformer (or a matching section as in the Zepp or J-pole both of which are just end fed half waves). If the wire isn't a half wave, you're effectively feeding it at a random point on the wave where the impedance could be perhaps 200-1500 ohms. A 9:1 will bring it down to the point where a tuner can compensate for the rest. There are quite well defined "random" lengths to use in order to avoid the feed point being too close to the centre or the end of the wave on all the bands it's designed for, and hence avoiding the impedance being too high or too low.
Thanks guys.
That was very helpful and informative. Thank you
Thanks Tom
Nice job thanks
Thank you too!
thx, dg2r?
Thanks for watching. 73 Peter
What’s a line isolator
Will cover thisin a video soon.
Interesting video, nicely presented and explained, thanks and I've subscribed. 73s G6XIB
Many thanks