VK2PRC Half Wave End Fed Vertical 20M Antenna for DX.
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- Опубліковано 29 вер 2024
- A complete step by step guide for, making and tuning a 20 Meter HWEF vertical antenna including impedance matching coupler. If you are unable to make one for yourself, email me and I'll make one for you. I am now also offering a more efficient coupler design that incorporates a 20M HWEF and a 1/4 wave ground plane 40M antenna feed point in the one box. See my second video in this series or Contact me for details.
NOTE: 1mm enameled wire MUST be used, NO other size!!!!!!!
The common mode toroids are FT114 core mix 43
MY EMAIL alexanderball50@bigpond.com
Amazing. I felt inspired by this video, made a lashed together version following your guidelines, and blow me down, it worked! Finland 1st test run strapped to garden fence!
Thank you Mark, I get lots of emails like yours. Imagine how well it will perform on top of a hill or next to the ocean, all a learning curve.
Outstanding performance 1/2
Top Bloke, inspiring with a sense of humour!
Thanks Alex one of best video on how to make the antenna. I already have one made from JP1QEC design very similar to yours. I use my vertical radiator with a link for 17m in line with 20m Halfwave. Slight compromise on 17m but it works fine chasing JP1QEC on SOTA summits on cw. Regards vk5cz ..
QSL from SW listener in Hobart TAS. Dec 13 2019 0830Z-0840Z. 14215kHz. Strength 3/5. Tecsun PL-660. 5m wire.
what a wonderful video. I have a half wave 20mtrs . You gave me lots of tips. Thanks Great!! Roger G4SEF
Alex have you ever measured the capacitance of the matching stub?
Absolutely fantastic video mate, thank you, I learned so much.... Thanks for taking the time 2e1evm 73s
Good instructional Alex, I have gone over to the EFHW myself after a few years of grief with the so called multiband 9:1 unun setup, my fav is a dogleg part vert part horz 20m wire on a type 43 transformer with a 1:1 common mode choke also on type 43 directly coupled in the box it does 40m and 20m low swr and 10m with a low value high voltage disc cap across the inner connections, my 10m only version is the same as yours and as you say on the yellow toriod not that it open much these days
73 phil 2e0tmi
Great to hear that Phil, I have also made a 6M version that works wonderfully as well.
Tried to build it today, but couldn't get SWR with my analyzer under 2:1:1. Resistor I measured was 2.96kOhm.
Will see what it does on the wire.
Hello John, the resistor value is OK, are you using 1mm enameled wire? this is a must! Send me some close up photos of your coupler to alexanderball50@bigpond.com and I'll help you out.
@@vk2prc978 with the 1:1 in place and on the wire swr came down.
I used a kit I ordered a while ago on eBay. The item I bought is not active anymore but a similar kit has 1.3mm enameled wire.
Don't know that could be a cause?
I heard Chile this evening on the vertical.
With everything in place: coupler, ugly balun counterpoise SWR was about 1.5:1.
Total coax length RG-8x is 50ft of which some length is used for about 14 turns on a 4" PVC pipe for the 1:1 ugly balun. The balun is direct under the coupler.
@@JohnZonneveld All of the people who have deviated from the 1mm wire have had problems and contacted me. If you are happy with what you have, all good, if you want to improve it. I would suggest using the 1mm wire like all others who have been successful.
@@vk2prc978 it was just what I had in the house. It was a 9:1 unun that I sacrificed for this test. I have a 12m Spiderpole in the backyard and the inverted-V was a bit heavy on it. ;)
Enjoyable viewing experience mate. What do you suppose the EFFICIENCY of this half-wave antenna is? You proved to us with simple demonstrations that there is RF signal radiated by each of the two counterpoise wires, and also by the coax shield between the choke and the magic box, when you pump a signal into the antenna from your rig. Thus, some unstated amount of your transmitter power is 'lost to the ether' from those three sites. I am guessing--and it's just a wild guess--that the efficiency of your antenna system would have to be something around 80 % at best ? One thing that I wish you "half-wave guys" would do in these videos is add one more Control Experiment: Connect your "ground lead" from the magic box to a substantial radial field, say 30 radials just laid down on the dirt around your pole. I'm talking non-resonant wires, let's say arbitrarily 4 meters long. I realize that a major objective in the Half Wave Game is to fashion a vertical antenna whose function is good enough without the need to put down a bunch of radial wires. A concealed issue however is this one: Does the radiation pattern of your 1/2 wave wire result in more utility, superior performance, etc. than that of a 1/4 wave wire taped to your pole (i.e. conventional vertical) and worked against a simple ensemble of non-resonant radial wires? Thanks. Many 73.
Hello James, lots of questions! OK I would say the efficiency of this impedance matching device is about 67% as apposed to my later high efficiency design that i'm thinking is close to 88% See my other video for the high efficiency model. This 67% efficient coupler has served me well as a portable station over the decay of our latest solar cycle. It has been a top performer. I am very excited about my new higher efficiency design and I'm really looking forward to the added benefits it will provide when 20M opens up for the next solar cycle. Now common mode currents on the end fed are a real thing, many believe they are small and don't cause any problems, I would say these people are QRP operators who simply ignore the currents and allow the outer shield on the feed line to radiate them and pretend they don't exist. When we start to use some power on the HWEF these CM currents have to be managed, in my portable installation my 2 short counterpose do the trick. I have a regular contact in ZL ZL3CHE Willem how uses a HWEF to great effect as a base antenna with a very extensive underground counterpoise field buried below his HWEF to dissipate his CM current and provide an even radiated pattern, he is a 400 Watt station. ZL3CHE is one of the biggest signals out of New Zealand. Now for the 1/4 wave, I love the simplicity of the 1/4 wave and I use it extensively with a Ground Tuning Unit in place of a counterpose and also with a wire counterpose in place of the GTU depending on the area I'm in. The 1/4 vert has a lower gain and a higher angle of radiation than the 1/2 wave end fed but is still a good performer for DX operation. Here is my choice of vertical antenna and location.
By the ocean, "I do mean close" a 1/4 vert with a GTU or a HWEF they will give equal results the HWEF may have an advantage in distance.
Elevated with poor soil and high winds I'll go for a elevated 1/4 vert for simplicity with wire counterpose
Away from the ocean but elevated I'll always go for the HWEF
James this information has been collected by myself over years of DXing and testing myself. Distant stations are always a good feedback for different antenna configurations and locations. It's one thing to sit in a large base station with huge power and read articles and give advice or criticism, it's another to go out in the field and do it. I wish I had a dollar for every time someone in the US or Europe has said to me, "you are the strongest station out of VK at the moment" as I'm sitting in a park or on the edge of the ocean with my British Army Backpack PRC 320 radio.
You gotta be a Pongo Sig ! I'm a 30 year Pusser WEEO ;)
Excellent Video keep up the great work and thank's for sharing, I look forward to building this antenna and trying it out for myself 73's Peter OZ66A
Made this design and utterly impressed. But can't see what length each radial is. It anyone has the answer plz. Cant wait to field test.
As I say in the video, the length of the counterpoise is not important for 20M. 2 wires at about 5M will be adequate to to look after any common mode currents.
@@vk2prc978 super thank you for replying, great instruction and tested yesterday,blown away how good it is. Love 20mtr band. Thanks again 2E0KFL.
Thank you for sharing this video, very instructive, I already built mine and the results were as expected. How about adding a BNC connector to connect there the coaxial capacitor for different bands (three different lengths) such as for 20, 15 and 10m. Adding this connector would affect the performance of the antenna?.Have you tried this? Thank you once again for sharing your experiences with the Amateur Radio community.
73 de K2WC
Yes you can do that works great! The commercial ones I'm making and selling now operate on a different system and are infact more efficient as well as incorporate a 40M option. The original concept in the video above works great . Thousands have been built and improved on. Alex VK2PRC
@@vk2prc978 Thanks for your quick response. Another question, I plan to make the connection of the BNC inside the coupler with a piece of rg58, would that be correct? I am a novice in the hobby that is the reason for all my questions.73
@@carlossilva.k2wc.542 Yes that will be fine.
Excellent
Many thanks for a very good instruction, clear and easy to follow. I now have an urge to make one! GW8UAP.
Alpha1 ?…great pirate call !
Thanks for the info. Just build one and it works very well. If I can build it anyone can. Thanks K7WHN
your drawing is confusing...the coax connection to the torroid? hot center wire is connected to last turn of torroid and the ground is connected just one turn to the same torroid?
Hello Sean, have a look on the video around minute 22 there is a comprehensive diagram. If you think my video is not good enough I suggest you simply move on to another clearer one, or better still put in the hundreds of hours needed and design your own. After you do this let me know so I can have a look and tell you I think it has shadows and I cant see it clearly. Clown!
How do you get 3,200 ohms with 11 turns on the secondary? 11 : 2 is a 5.5 to one effective turns ratio. 5.5 squared = 30.25 and 30.25 X 50 gives secondary impedance of 1,512.5 ohms and not 3,000 ohms. Standard transformer theory.
Well, I guess the 1000s of people around the world who have made these are wrong and this matching devise really doesn't work after all. The emails I get every day thanking me for the amazing results people get are all scam emails. Before making this assumption, have you made the coupler and tested it? I suggest you make one and them comment.
@@vk2prc978 Essentially what your antenna does is to develop a resonant tank circuit at 14.2 MHz. With 11 turns on a 200-2 Iron core the calculated inductance is 1.45 uH and the capacitance at resonance is 87pF. This is a very clever way on building a no radial half wave end fed antenna and the selection of the core is very important if you want to use a coax as the capacitor in the tank circuit. For example, using an FT240-43 with 11 turns would generate 211 uH inductance in the secondary and the resonance capacitance would be about 6/10 pF which would be impractical to use. But 87pF capacitance is easy to obtain with a trimmed open coax (RG8X) at around 30 pF per foot.
I duplicated your design using a 200-6 core (I didn't have a 200-2 available). I do think a 200-6 would be a better choice than a 200-2 because it has a broader bandwidth and could be used from 3-30 MHz. I have not yet checked to see if you design will resonate on harmonic frequencies.
One other plus with your design is that, on 20 meters the SWR is flat across the band. Thank you for taking the time to share your design.
@@hankhamner3671 Yes if you read through the comments I have recommended upgrading to a T200-6 toroid, also see part 2 of this project at ua-cam.com/video/fIyYUtmVHrM/v-deo.html
Hey mate. What are the chances of clicking U $$ for a coupler. Or let me know where I can buy the parts. I'm around the corner from you in Liverpool
Hello Ezat, you can get the toroid from Mini kits Australia, Google them, the 1mm enameled wire, and all the other parts including the box from Jcar Electronics. The 3K resistors, I would order 3 x 1K 3 watt Metal film resistors from ebay. Remember only use low power AM when tuning your coupler or you will burn up the resistors.
@@vk2prc978 thanks Alex. Where's the fishing pole from? There's a fishing factory in Milperra called Gansel that sell them but not sure if they have 10m. My call is VK2EZT.
Got all the pieces now. Should assemble this week. I'd love to share my result if U can be contacted.
@@vk2yi81 Hello Ezat, send me an email via my email address on QRZ
Hi Alex, I just wanted to say how much I appreciated your videos on EFHW Verticals. My version works a treat! I set up the Balun on the bench and used a variable capacitor to tune it. Then cut the coax (Capacitor)to the reading obtained on the variable capacitor.
It is tuned for 14.050 MHz My first contact at 100 Watts was the Red Sea MM!
3000 miles plus! So well pleased. I would recommend watching both videos before ordering parts. So many thanks I must have watched both videos a dozen times. They are very well thought out.
73,
Richard
Great video Alex. I was puzzled by the impedance transformation, but looking at your comment about rethinking as 2k5 at the feedpoint and the other comment about 2 to 13 turn ratio, it all fits - 4 to 169 impedance ratio meaning 50 ohms transformed to 2k1. Nice tip regarding the raised feedpoint. Got to make one of these!
Sorry to quarrel but a half wave IS a dipole whether it's fed at one end or in the middle OR off centre.
The Di in dipole doesn't mean two bits of wire fed in the middle. It alludes to the power distribution of the half lambda wire, however it's excited.
Put up a half wave wire with NO feeder..ANYWHERE. It will still accept incoming RF at its resonant freq. with dipole type distribution even though nobody is making use of it.
This does not in any way detract from the value of the A1 video of VK2PRC.
I'm sure that I will learn (and utilise) a great deal from the remainder his ACE video... Good on yer Cobber or don't they say that anymore? Fair Dinkum? God...Am I that old, Blue?
Nothing better than watching guys using a combination of homemade and old army stuff kicking butt. Alex, you da man!
Thanks for taking time to make this detailed build and operation video.
Why do you use a 3 kΩ terminator for a transformer with an ipedance of 30:1 (5.5^2)? I would expect it to be 1.5 kΩ.
Hello again Alex hope yoy are doing well. I will be building a second one with 20 and 40 meters in same box. My first one I added 40 meter box to 20 meter set up. Thanks again my friend!
Hello Alex, came across your video (really great, thank you for creating and publishing it!) and wanted to ask you - why "NOTE: 1mm enameled wire MUST be used, NO other size!!!!!!!"?
i.e. we just need to have a resonant circuit here, so basically 13 turns on toroid will create 2.03uH so you will need about 62pF to make it resonant for 14.2Mhz. You can use any wire that will be able to hold the required power, for 100W+ anything above AWG18 (that is 1mm) should work fine. Did I miss something?
P.S. Curious why did you use only 13 turns (42:1) instead of 14? (that would making it 49:1)? Especially when you say EFHW impedance will be 3000 Ohm, that is more close to 64:1.
Hello Alexander, quick question, How many turns would be necessary to obtain good results on a T130-2 toroid?, 18 awg enameled wire will be ok?. It’s for use with 50 watts maximum. Thank you!!! 73
Thanks for this easy to build DX antenna AleX ,and say hello to ELON MUSK from me 🥴
What toroid, how many, how many wraps, and what coaxial cable do you recommend for the RF choke on this coupler? Or would you use a Reisert Method and one toroid? Using your video I made a coupler.
Thanks I’m a total newbie and have been looking for this sort of info. Very clear video with no waffle 👍
good to make your contact today. 73 VK4FJST
hi just been re looking at my build of this matching box for 1/2 wave ant i had used rg8x for the coaxial capacitor i could never get the swr good as you had got but i have now changed it for rg58 now its good like yours a good tip dont use RG8X
Yes my original concept uses RG58.
Outstanding! Thanks for the DX help!
KF0IDJ
Thanks for the great tutorial. I used this antenna on 20m and 40m successfully getting in to Europe, US, Russia and NZ from Brisbane in the Oceania contest. Very simple to build and deploy. Really impressed.
I saw a video where someone opened up the match box of an LNR endfed antenna. They us a similar coax capacitor matching stub in there system too.
Excellent video, well thought out and outlined.
My best to you an your in VK land.
73 mate
wd4dda
TNX FOR SHARING THAT VALUABLE VERT. BUILD INFO , APPRECIATE THE EFFORTS . 73S
A great Master’s class in antenna building. Thanks 😀
Cracking job and very well presented!
You're using two counterpoises whilst in the park after reccomending only one on the whiteboard.
OK when operating on 20M with the HWEF the counterpoise is only used to dissipate the common mode currents from the HWEF. I could use any length counterpoise I want but it must be long enough to dissipate the currents. The more power you use the more counterpoise you need. I use 2 short lengths of wire random length. When using the 20/40 combination in the 40M configeration I tune the counterpoise to make my 1/4 vert resonant. If I switch back over to 20M then any length counterpoise will do. I usually run between 2 and 70 watts but my HWEF design can handle up to 400 watts.
Built one today , tuned easily to 1.24:1 @ 14.200 , that’ll do for me. Many thanks Alex for inspiring this 83 yr old
enjoyed the last contact with the "space voyager" requesting you relay a message for him, great antenna. I think I am going to have to build one for myself,,,thanks wq7s
Hi, I great video, thank you. I feel that a rectification is needed in reference to the angle of radiation. Whilst as per your writing the angles are 32, 26 and 15 degrees - they are actually measured in respect to the ground plane - not as marked on your drawing (the vertical plane). Regards, Jus
Ups. It has already been mentioned in comments - may be good idea to change the intro to the video to reflect it rather than relay on assumed knowledge of the person watching it.
Read earlier comments, these issues has been done to death.
Now building another for a friend , you have started something Alex !
Thanks Alex. I enjoyed your informative, easy to follow video. I like the tuning method. I wonder if the tuning cap is broadband across the common HF bands, allowing multiband operation by changing antennas accordingly? I imagine that it is, because it was tuned into a resistive load. Regardless, your coupler and antenna configuration ticks a lot of boxes. 73, from VK3 PCJ.
Hello John, yes by changing the length of the coax tuning capacitor you can tune the coupler from 40M to 10M band. 10M band being the shortest, about 7cm
A low angle of radiation would be 15° from the horizontal, rather than the vertical, surely? 15° from vertical is 75° from the horizon, which is nearly straight upwards.
Yes this has been brought up in previous comments, I might add at this point for every comment like this one I get a least a 100 " thank you, what a great video" type emails. I made a mistake in my presentation, big deal! I know what I meant and I would say the majority of people who watched the video and saw the mistake would simply realise i made a silly mistake and moved on. But now and then someone has to make a point of mentioning it and getting their name on it in the comments under my video. Well your names there now Phil just like Sean below who just couldn't contain himself when he noticed a shadow in the video and just had to complained about it. I'm not going to replace the video Phil. I guess where stuck with it the way it is.
I just worked you Alex on 7.144 40m and you are romping into Geelong from Campbelltown. Nearly 20+ and you're running 70 watts. The antenna works a treat! I look forward to chatting to you again soon 73 from Lara near Geelong! Craig VK3CRG
Cool video. I've been playing with EFHW antennas and UNUNs, and found a wonderful way to cover all bands from 160 thru 10 using a multi tap UNUN. No tuner is ever needed. SWR generally well below 1.5:1 and often a perfect match. Your vid is a vertical half wave... which is just my antenna stood upright. lol. If you or anyone wants to see the multi tap UNUN, search on '80 EFHW & Mullti tap UNUN part 1 of 3 Intro & Demo'. 73 OM and happy new year!
I'm sure that your approach is very good, N7NK. Mixing yours conclusion with the masterclass above will be good for all fellows hams. Contratulation.
73 from PP1RD
Excuse my bad English.
@@zeferpp1rd572 Thank you Jose. Your English is wonderful. Much better than my Spanish! :)
N8NK QRP - My native language in Brazil is Portuguese. But all our neighbors in Latin América are Spanish speakers. I like and try to comunicate in both Spanish and English languages. But foreigner languages always are difficult compared the native, as well.
73 from PP1RD Fernando
Where do you get the fibreglass 10m squid Pole most I see are carbon fibre which is not supposed to work.
I use these www.ebay.com.au/itm/HAM-Amateur-Radio-Telescopic-Squid-Pole-10-Metres/202666050492?hash=item2f2fd683bc:g:50wAAOSwV0RXqq5P:sc:AU_StandardDelivery!2560!AU!-1
Specifications:
- High Quality Fibreglass Construction (nil carbon for radio antennae usage/interference)
- Approximate wall thickness 1.1mm
- 10m Pole collapses to approx 1.2m length.
- 10m Pole constructed using 10 parts
- Overall Weight: 1.6kg
- Tip Diameter: 2mm
- Base Diameter: 48mm (excluding screw cap)
- Rubber cap to close open end
- Plastic screw cap at base
- Supplied in a resealable Poly Bag
VK2PRC thank you for the information VK1FJMG
Great video Alex. Thanks for the link and great to chat to you on the PRC320. Cheers Ian. ZL1HIM
So how does the secondary 11 turn wire start after the primary. Is it the same wire or a new winding ?
It's the same continuous wire with a tap soldered on.
VK2PRC Thanks for the info ! I’m definitely gonna give this antenna project a shot ! 73 To you sir !
The coupler could be replaced by the ubiquitous 49:1 EFHW transformer. Another simple way to match a halfwave vertical (or any end fed antenna) for your band of choice.
Great to work you today Alex from Lara while you were pedestrian mobile in Campbelltown. Booming signal into Geelong. 73! Craig VK3CRG
Great. Lots of detail. So many others assume you know some stuff, which I don't know. Bravo.
Absolutely excellent video Alexander, thank you so much for this! This is definitely my next project for POTA use.
Great video, thanks for your excellent work. Mostly ’they’ say, take a 100 pf cap, but you’re coax method is just great . Helped me a lot.
Vy 73 from Switzerland de HB3XBL 👍🇨🇭
How much for a ready made matching unit .
Email me on alexanderball50@bigpond.com and we can discuss.
Is this an fixed tune fuchskreis? It looks like. (maybe the englisch translation is foxcircuit, dunno).
nice video
… longest dx ever 😂😂
THANK YOU, I am kind of new to the HF part and am learning a lot from videos like your! 73. W4DES
gonna Build it this week , Tnx so much for sharing your Knowledge and efforts ! 73s
hi alex, could you put part numbers for the rf choke up please, i see you use 8 teroides? cheers zl1jre
thanks very good m8
why not just use a small trimmer capacitor? make it even easier. use a 49:1 unun and get 1:1 to 1:3 across the 20m band. Why make things harder than they need to be
For QRP purposes the idea of a small trimmer cap is good but as you increase your TX power so the voltage across your capacitor increases. For power at 100 watts and above thousands of volts can appear and will blow your trimer. The idea of the coax capacitor is to withstand these extra high voltages.
@@vk2prc978 something must be wrong with mine then, trimmer cap has not blown at 500 watts
@@n0vty873 Well if that's the case you should put your design up on youtube. I'll notify the thousands of people around the world that have built my design and I'll direct them to your video. following that I'll take my video down from my channel.
@@vk2prc978 it is simple use a trimmer cap instead of a coax cap, ceramic type to handle the high voltage. It is not my problem that you can't see that far ahead of yourself. have a wonderful life
If you choke the coax at the feed point a counterpoise will probably be required, choking the coax closer to the tx may delete the requirement for a counterpoise but also a connection to ground may prove to be desirable.
Hi. You may have said it so forgive me for asking, what gauge/size is the enamelled copper wire ? Toroid is on order so its full steam ahead....cheers
1mm square
Cheers for that.
Can an air spaced choke be used ?
Something like a 120mm former with the appropriate coaxial turns. It would help to keep the cost down ?
@@davidbridge3542 I imagine this would work ok, The whole purpose of the RF choke is to stop any common mode currents traveling down your feed line. The more power you transmit the bigger the effectiveness of this choke has to be plus the more wire in the counterpose is required as well.
Hi Alex. Its awhile since my last contact. I've finished the build and was testing yesterday. The swr is very good, but then I tried it with a coax feed with an 110mm air spaced choke, the swr went off the scale. Vertical element good, radials in position.
Any thoughts?
I also made a totally separate wire for 40m and got that with a good swr. But, I can't have them on the mast at the same time, just have to do a quick swap over.
Cheers David.
Hi , will this work for tuning a 5/8 th on 20 metres
No a 5/8 has feed point impedance close to 50 ohms, a HWEF has an impedance above 3,000 ohms.
Thats a shame and thanks for your help .
Thanks for sharing. Excellent info, much appreciated.
Hi Alex,
Your coupler arrived in the States in 6 days.
Assembled my antenna, attached the coupler, SWR was 1:1.3 at 14.225 !!!
Attached coax directly to TX, bypassing the tuner - did not need it. First contact was Brazil, then Los Angeles,
Italy, Chile, then lastly northern Brazil.
All were receiving me at 5/7 - 5/9.
You done good my friend - I haven't even attached the 2 counterpoise wires yet.
Thanks again, will look for you on the air soon.
Lou KG5HBL
i am going to build one for my home qth with a bypass switch so i can use it as a 40m 1/4 wave as well same for portable one as well chris
How has this turned out for you?
@@RonPoulin hi the portable one on 20m is perfect for tuning 1 : 1 match on 5 watts but at home i can not get the match so good 1:16 swr on 20m i got a week off in October i will re do it see if i can get it higher up the pole in the mean time i touch it up with the atu in the 7300 40m is good and i can get 60m by adding a coil to the base of the 40m wire chris G0wfh
Great video Alex, very informative. Wouldnt mind having a bash at that myself as Im inland by about ten hours in Canada. No saltwater fro me. Looks a good park option. Thanks Simon VE3/G7HCD VA3SII
I am curious to know if a 9:1 balun can be combined with a coax capacitor to tune the half way wire the same way you did in your video?
Excellent antenna. I have done a few edn fed using the same materials and also for 10 meters i used just a coil made of pvc and for the capacitor same has you rg58 and it worked fantastic. Now my question for you is if you know the impedance for 10 meters of aluminium tube? 3000 ohms is ok for a wire halfwave element, but for aluminium tuve i think could be less and also a little shorter too.
My next proyct will be a 10 meter vertical meda of tube and using this coupling form 3000 ohms to 50 ohms.
Thanks in advance and 73 from Nelson CE3LLP
I think you will find the end fed impedance of a wire and aluminum tube antenna will be the same. The only difference being as the cross section of the antenna gets larger it's length to resonance will be shorter. So an aluminum tube antenna will tune shorter than a wire antenna.
Hi Alex , I finally managed to build one of your transformers , its all hot glued in place , I used a 3k ohm resistor to tune it , after reading through all the comments I have discovered you now tune it with a 2.5 k ohm resistor should I take mine apart and re do it with a 2.5 or just leave it as it is how much benefit would there be in changing it all thank you for a very interesting video I have watched it about 10 times now l to make sure I get it all right .
2.5K or 3K still OK , should tune fine when you trim your antenna to resonance.
A lot of good information, a bit waffley but worth staying with for the quality of the information given. I've subscribed.
Hi from Jim VK3AMN now I got new Ant to build great stuff keep it up regards Jim
Excellent video and easy to follow. I really liked the way you tuned the coax which I used to tune my EFHW transformer and then measured the cap on the coax and replaced with same value high voltage cap. Excellent video. G4PEY
Great design. Here's a potential upgrade; why not make the counterpoise detachable? You could have different antenna lengths and a set of counterpoises to match, and it makes for easier storage, plus you'll only need one box for multiple bands.
His driven element is cut and tuned to half wave on 20 and uses a capacitor to match and tune. The counterpoise lengths have little effect on tuning in this case. I believe you are suggesting a vertical endfed longwire with various length counterpoises to choose from for different bands. The problem is that they will not have the same propagation field as a half wave.
A question for you mate: I personally dislike toroids (no offense- most people love'em) so instead I'd like to try an air-wound coil/ transformer of about 2 uh total inductance and tune it the way you did (but with a NanoVNA). Do you think it would work? ( I guess I'll have to try it to find out)
Edit; I modeled the match network with LTSpice and it works like a charm. I used 1.95/.05 uh transformer with .9 coupling (K ) and 50pf//3000 ohm across secondary and I get 50 ohms, no reactance, around14.1 Mhz.
Sorry I have no idea. I suggest you try it and see.
Thank you for the QSO yesterday to Hawaii on this setup.
Check your spelling in your intro
Wats ta matar wit mi spellin ?
Excellent video most interesting, can't wait to build one, will be forwarding this link to the guy's of OTLEY RADIO SOCIETY W YORKSHIRE. Kev G0KEV.
Thanks for your time
Can you show how did you wined the toroid can't really see.
Alex, Thanks for the instruction. This past week I built your 20m HWEF transformer combined with the straight pass-through for the 40m band in one box. I am using only one SO239 connector on the box for both 20m and 40m. I will see how that works out.... I have not tuned the coaxial capacitor yet. I have a fiberglass telescoping 12m spyder pole I'll be using with a GTU I have built, like yours, for tuning the 40meter wire without ground radials. Lot's to look forward to in the coming weeks. Hope to catch you on the air soon. I also live by the ocean so this will be fun. KE4LJH
The problem with using only to one connector is when you use the 40M 1/4 wave option you are still connected to the toroid. This will put your antenna and toroid primary in parallel.
i worked at the factory in Langold Worksop where they was made . and then in the military used one .
Ok Alex I've got to ask
Is this as good as it gets? I'm getting too old to experiment with less effective antennas. Ive learned alot from this build especially the rf. Appreciate your post!!
Fantastic video! Thank you Alex!
Hi Alex, I made this antenna, using the coax stub to tune it, but here is the catch I installed it as an upside down slopper! The feed point is just inside the top of a UPC window, about 20 feet above the ground, the end of the antenna goes to a small tree and is about 10 feet above the ground, from the box, I have a 19 foot, vertical counterpoise hanging down to above 1 foot above the ground. In this figuration, it gives better reports than my tunable delta loop, and the twenty-meter dipole in my loft.
Interesting! Amateur radio and HF antennas always different things to try. Well done.
If I attached a Artificial Ground Unit that is of course tune able will it do the same as your trimmed coax? Also with my being a former CBer I have always wondered why 1/2 wave antennas are so uncommon in the Ham community. I greatly appreciate you sharing your experience. I have been pondering for awhile why using a 1/2 wave on 20 meters wasn't do-able. I have a 33ft aluminum pole made up from old CB verticals that I want to try and maybe using your ideas, something should work. Thank very much !!!
In answer to your first question about a GTU. No it wont replace the tunable length coax cable. The coax used as a capacitor is in the region of about 10 to 15Pf. A half wave wire antenna for 20M band is approx 9.8 meters long, using an aluminum tube will reduce this length, simple try it and tune the length for best SWR
whilst i have a commercial multiband end-fed antenna, i found the theory and practice presented in this video very useful to get the most out of my antenna and radio. Thank you !
Hi Alex, brilliant video and very easy to understand. Now, In my situation I have to operate in a poor location with difficult geography in a listed area, hills, trees, and overhead telegraph cables; my question to you is how critical is the height of the driving element please? 30 foot might raise a few eyebrows, can I get away with 20-25' for example? Can I also get your thoughts on coax length as I have a long run up to the antenna, in my case its unfortunately unavoidable
Many thanks indeed, again brilliant video! I hope to build this if the design can accommodate the compromises I allude to above. 73
My design is for HWEF antenna, the element length is approx 9.8M tall, no shorter. I have also found mounting the antenna close to the ground reduces the performance, optimum height for portable operation about 1.8M. Long coax runs minimize power available at the feedpoint. a 100FT of coax can reduce you power by up to a half. When portable my feed line is kept as short as possible.
Excellent excellent video. Thank you very much. Just curious on the construction of your mast. I love seeing what different hams do.
Also, did you ever get a chance to sweep your antenna across the whole band to see its performance. Have fun, stay safe and stay healthy. 73 howie ki4bns
I have a video up on my channel on constructing the antenna mast supports I use.
Excellent video Alexander. Just returned to the hobby after 51 years so re-learning all this stuff. I have a Decca KW107 Supermatch which accepts either balanced ladder line feeder or unbalanced. Do I need a matcher such as your unit or possibly a 9:1 unun or should the Supermatch be able to resonate a half wave wire connected straight to it? Many thanks, Phil G8BHB
I would think it may well, why not cut an antenna to 9.8M long and try it.
Interesting setup, thanks for the video, didnt realise that 1/2 wave end-fed impedance was as high as 3000 Ohms !
How did you know that 3k ohms was match you were shooting for at the end feed point? What would be the ohms at the feed point of say a 10 meter antenna? Also, why not use a variable capacitor rather than the sniped coax? Seems that if your field results had high swr a tuning capacitor would be more convenient to adjust. I really enjoyed this video and very much appreciate you sharing your techniques and methods. 73 de K6TJO
Hello Tim, in answer to your question. Internet research led me to the 3K ohm assumption of the impedance value. Since making this video experimentation has now changed my view on this to 2.5K In practice there is not much difference to the end result but I now use 2.5K ohm. I use the coax capacitor for a number of reasons. Firstly it's cheap! Secondly it never has to change or alter, 3rd It will cope with very high voltages if high power is used. 4th it is very low value about 15Pf.
The Impedance of a 10M endfed is also 2.5K Same turns on the toroid with a shorter coax capacitor, use T200-6 toroid yellow.
VK2PRC, what ferrite core material do you use for the common mode choke? How many turns and what size coax are you using? RG8X? Thanks! WD0DUD
Garry FT50-43 Ferrite Fair rite are ok for the common mode choke. As many turns as you can fit. I use RG58 but keep my transmission line as short as I can.
hi Alex nice set up very good video 73 3njoy from kb2uew
Great Video Alex , l'll certainly give it a go ! VK3BRX