VK2PRC Half Wave End Fed Vertical 20M Antenna for DX.

[@dougtaylor7724]

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.

[@richardputnam3349]

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

[@mikes6844]

Still remains my bible on EFHW, great informative vid. 40 years plus in amateur radio and a career in industry I realised I know so little and have still much to learn. Thanks to the spirit of amateur radio that information is shared so freely without personal gain. What a great hobby.

[@vk2prc978]

Thank you Mike, you would be surprised how many people email me with glowing reports on this project.

[@rogerbirchall9037]

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

[@mlanagan]

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.

[@jdsnapp]

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!

[@franzliszt3195]

Great. Lots of detail. So many others assume you know some stuff, which I don't know. Bravo.

[@vk3crg]

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

[@sofjanmustopoh7232]

This is an awesome built . Especially the coax as capacitor . Just like the gamma match on yagi . Love it . Saving this for future build .

[@ljansen2157]

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

[@PaulOfford]

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!

[@MrPaulstrivens]

Thanks I’m a total newbie and have been looking for this sort of info. Very clear video with no waffle 👍

[@peterschjellerup]

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

[@alzeNL]

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 !

[@lenbaddeley957]

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.

[@vk2prc978]

Interesting! Amateur radio and HF antennas always different things to try. Well done.

[@brianbrown4965]

i worked at the factory in Langold Worksop where they was made . and then in the military used one .

[@rogerbirchall9037]

Now building another for a friend , you have started something Alex !

[@vk3crg]

Great to work you today Alex from Lara while you were pedestrian mobile in Campbelltown. Booming signal into Geelong. 73! Craig VK3CRG

[@stevecrawford3551]

A great Master’s class in antenna building. Thanks 😀

[@beemcbike]

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 👍🇨🇭

[@donaldsmith3048]

THANK YOU, I am kind of new to the HF part and am learning a lot from videos like your! 73. W4DES

[@gjones4702]

Thanks Alex for the video. I built mine last week and got 1:3 on the whole 20 meter band. My first contact was ZS1SBW in Capetown South Africa on 100 watts, 8066 miles from WV. He said the next stop was Antarctica. Thanks again for the easy to follow video. Ralph KC8NRN

[@vk2prc978]

Great! thats the sort of performance I would expect.

[@jdsnapp]

Thanks Alex for this info. I just finished mine and accidently cut off too much adjusting swr so I had to add back accordingly. I really didnt think it would work at first as I proceeded to trim back coax. Then I seen the swr come down! Wow! It works! Many thanks for your hard work.

[@vk2prc978]

Hello John glad it all worked out for you. Watch the video again closely to see mine in use and I'm sure you will get the same results. Remember we are in a solar low so contacts arn't as easy these days. Yes trimming the coax is a surprise when you get close to the magic length. People also need to be aware some side cutters may short the coax out when cutting so after clipping check to see coax isn't shorted.

[@richarde735]

mars, wow... your antenna is out of this world

[@G0ogs]

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.

[@U812-k7j]

Alex have you ever measured the capacitance of the matching stub?

[@avrumo]

TNX FOR SHARING THAT VALUABLE VERT. BUILD INFO , APPRECIATE THE EFFORTS . 73S

[@michaelclarke5932]

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

[@tomkeady1750]

Alex, thanks so much for the great video on the build and principle. I built your half wave end fed vertical for 20m an it is nothing short of spectacular. I have used it for my last 4 POTA (Parks On The Air) portable activations and have had nothing but success with it. Activating parks in Nebraska and consistently getting to both coasts, Canada and the gulf is a treat. High lights have been Hawaii, France and Spain. It has been everything you claimed it to be, except maybe that Elon Musk contact. Just finished your 40m add-on, hope to test it as soon as the Nebraska weather warms back up. Again thanks again for all you do. 73 from KE0JVS

[@vk2prc978]

Thanks for the flowers Tom. Yes it is! I use it every time I get on 20 and 40M portable with glowing signal reports, I wish I had a dollar for every time someone says I'm the strongest station on the band. With the virus self isolation here in Australia I'v set up my portable station in my back yard and still getting great reports. BTW Starman is still checking in now and then. lost him for a while when his orbit was on the far side of the sun but he back now. 73

[@tomkeady1750]

@@vk2prc978 Gosh....does this me we're going steady?

[@n8nkqrp595]

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!

[@zeferpp1rd572]

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.

[@zeferpp1rd572]

73 from PP1RD

[@zeferpp1rd572]

Excuse my bad English.

[@n8nkqrp595]

@@zeferpp1rd572 Thank you Jose. Your English is wonderful. Much better than my Spanish! :)

[@zeferpp1rd572]

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

[@davenelson413]

Interesting setup, thanks for the video, didnt realise that 1/2 wave end-fed impedance was as high as 3000 Ohms !

[@JimMcNabb44]

Hi from Jim VK3AMN now I got new Ant to build great stuff keep it up regards Jim

[@rogerbirchall9037]

Built a HW one for 40m , looking good , it has quite a long tail for resonance

[@kazcat8096]

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

[@vk2prc978]

Yes my original concept uses RG58.

[@JimbobandJo]

Great video Alex. Thanks for the link and great to chat to you on the PRC320. Cheers Ian. ZL1HIM

[@acestudioscouk-Ace-G0ACE]

A lot of good information, a bit waffley but worth staying with for the quality of the information given. I've subscribed.

[@johnnybigpotato2404]

Thanks for the video. Very cool idea to use coax as the high voltage capacitor.

[@prestonshute7243]

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

[@DucatiMTS1200]

Cracking job and very well presented!

[@dezwatson6993]

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.

[@drewmccoy8305]

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.

[@ackerkenton]

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!

[@vk2prc978]

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.

[@glennnofsinger1658]

Thank you for the QSO yesterday to Hawaii on this setup.

[@dsmith004]

A very nice and practical demonstration.

[@willian.direction6740]

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 ..

[@paulhillier9281]

Top Bloke, inspiring with a sense of humour!

[@kazcat8096]

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

[@RonPoulin]

How has this turned out for you?

[@kazcat8096]

@@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

[@19134ANDY]

Thanks for your time Can you show how did you wined the toroid can't really see.

[@ThingEngineer]

Absolutely excellent video Alexander, thank you so much for this! This is definitely my next project for POTA use.

[@jansb984]

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.

[@vk2prc978]

Read earlier comments, these issues has been done to death.

[@dback4430]

Thanks for all the time and info you have into this . Great Job. I will build one of these and try it for 80 meters .

[@vk2prc978]

I really don't think this type of coupler would be suited for the 80M band

[@АндрейДенисюк-ш7п]

D Back Do you already have 40m tower for it? ))

[@dback4430]

@@АндрейДенисюк-ш7п Its in a inverted L and works great .

[@АндрейДенисюк-ш7п]

@@dback4430 Vertical and its great radiation angle is the topic of this video.

[@dback4430]

@@АндрейДенисюк-ш7п I know but 135 feet straight up is hard . The 20 meter version i made is also great .

[@tomtwist1081]

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.

[@paulhastings3109]

Outstanding performance 1/2

[@carlossilva.k2wc.542]

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

[@wildbill1]

I’ve been looking to build a good 20m DX antenna. I already have a couple of commercial made multi band EFHW with a 49:1 transformer. I’m going to cut a 33 ft length of wire and run it vertical with one of the transformers and try it out. Thanks for the idea

[@paulkazjack]

Have you tried it yet??

[@wildbill1]

@@paulkazjack yes but didn’t notice any improvement over it being horizontal.

[@no-ee]

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?

[@graemehannaker2999]

Great Video Alex , l'll certainly give it a go ! VK3BRX

[@mikemiles3068]

Fantastic video, love the end feeds❗️

[@W-733_KWX]

I'll definitely would build one ; i have found out i would get a little longer box and have the choke in there too :)

[@HarmonicaMustang]

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.

[@aarongriffin81]

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.

[@djdommes9302]

So how does the secondary 11 turn wire start after the primary. Is it the same wire or a new winding ?

[@vk2prc978]

It's the same continuous wire with a tap soldered on.

[@djdommes9302]

VK2PRC Thanks for the info ! I’m definitely gonna give this antenna project a shot ! 73 To you sir !

[@DucatiMTS1200]

Great work Alex - a very practical and purposeful video. William - (GI8WFA).

[@avrumo]

gonna Build it this week , Tnx so much for sharing your Knowledge and efforts ! 73s

[@55555netman]

hi alex, could you put part numbers for the rf choke up please, i see you use 8 teroides? cheers zl1jre

[@richarde735]

what a great explanation of the design and functionality of your setup! how are you measuring the length of capacitive tuning coax?

[@zeferpp1rd572]

Calculation after reading Coaxial Cable data sheet, I presume. Generaly, around 100pf /m. So, measuring and cutting.

[@bradmcmahon3156]

QSL from SW listener in Hobart TAS. Dec 13 2019 0830Z-0840Z. 14215kHz. Strength 3/5. Tecsun PL-660. 5m wire.

[@pincus321]

Where do you get the fibreglass 10m squid Pole most I see are carbon fibre which is not supposed to work.

[@vk2prc978]

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

[@vk2prc978]

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

[@pincus321]

VK2PRC thank you for the information VK1FJMG

[@hannesmans3763]

Good day thanks for the gr8 demonstration and info. Will you be able to install a BNC fitting for the Coax/cap. The idea i have is to have a pre-trimmed cap per band. . . also what ferroids dit you use for the chock.

[@vk2prc978]

Yes a BNC socket and BNC plug in tuning coaxes for 10,15& 20 Meter bands are possible, I know a few people who have done that. Use FT140-43 Ferrite Toroid for the common mode feed line choke.

[@vk2prc978]

Yes a BNC socket with BNC coax pigtails for 10,15,20 are possible. Easy done! Use F114 core mix 43 for the feed line choke.

[@carlossilva.k2wc.542]

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

[@vk2prc978]

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

[@carlossilva.k2wc.542]

@@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

[@vk2prc978]

@@carlossilva.k2wc.542 Yes that will be fine.

[@Streetdirt]

Thanks for sharing. Excellent info, much appreciated.

[@turinskiboy]

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.

[@vk2prc978]

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

[@男メロウ]

Hi ~ what is the Gain of a EFHW ? ~ GREAT VID Thnx

[@gjones4702]

About how long would the tunable coax be for a 40 meter antenna?

[@michsmi8297]

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

[@vk2prc978]

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.

[@beachbum9869]

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

[@vk2prc978]

I have a video up on my channel on constructing the antenna mast supports I use.

[@rogerbirchall9037]

What is the starting length of the tuning coax Thanks great vid Roger

[@vk2prc978]

Start at about 90cm best to be a bit long than short.

[@rogerbirchall9037]

@@vk2prc978 thanks

[@rogerjenkinson5034]

what a wonderful video. I have a half wave 20mtrs . You gave me lots of tips. Thanks Great!! Roger G4SEF

[@M6MRP]

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

[@vk2prc978]

Great to hear that Phil, I have also made a 6M version that works wonderfully as well.

[@JohnZonneveld]

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.

[@vk2prc978]

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 [e-mail] and I'll help you out.

[@JohnZonneveld]

@@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.

[@vk2prc978]

@@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.

[@JohnZonneveld]

@@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. ;)

[@polzovotel]

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.

[@kevballard1967]

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.

[@vk2prc978]

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.

[@kevballard1967]

@@vk2prc978 super thank you for replying, great instruction and tested yesterday,blown away how good it is. Love 20mtr band. Thanks again 2E0KFL.

[@quicho1961]

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

[@vk2prc978]

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.

[@larspregge6420]

Is this an fixed tune fuchskreis? It looks like. (maybe the englisch translation is foxcircuit, dunno). nice video

[@mikebarnes9858]

Great video...I would like to build one myself. However, I could not fully see the wiring of your coupler. Could you show a wiring diagram?

[@gabiball3272]

Mike go to about minutes 19 of the video I couldn't have made a clearer diagram of the coupler.

[@gabiball3272]

Mike 18 minutes into the video there is a very clear diagram.

[@davidbridge3542]

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

[@vk2prc978]

1mm square

[@davidbridge3542]

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 ?

[@vk2prc978]

@@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.

[@davidbridge3542]

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.

[@americaswayout4489]

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 !!!

[@vk2prc978]

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

[@MrPerrey]

Very nice video with detailed instructions. I had only one doubt about the iron poder core. Due to the low permability of material 2 a Ferrite core of material 43 would not be more suitable? I had learned that Ferrite is sutible for transforming devices since iron poder fits to make inductors for filter outhet matching cirquits. You ever tried a ferrite core in your impedance transformer?

[@vk2prc978]

Hello Wolfram, I'm sure this design would also work with other Toroid cores. Since making this video I have switched to the T200-6 yellow Toroid simply because I want to use the same toroid for making couplers for 20,15 and 10M band. The Fair-right FT240-43 would also be a good choice. But be assured the T200-2 works just fine in this 20M application.

[@vk2prc978]

In above reply FT240-43 should have read FT240-52

[@MrPerrey]

@@vk2prc978 right, material 43 or better 52 for higher bands

[@SimonWilton]

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

[@1000000volts]

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 .

[@vk2prc978]

2.5K or 3K still OK , should tune fine when you trim your antenna to resonance.

[@cmortlock81]

Absolutely fantastic video mate, thank you, I learned so much.... Thanks for taking the time 2e1evm 73s

[@markgosnell3196]

Im new to all this, just wondering how many ohm each resistor was you have in series? thanks

[@vk2prc978]

All up 3K ohm metal film resistors for bench load. Before you start watch my part 2 titled VK2PRC My second video in the series of 20M & 40M vert. antenna configurations for portable ops

[@markgosnell3196]

@@vk2prc978 Thanks, heard you in Toowoomba today your signal was the strongest by far...usually is.

[@michaelartingstall3785]

Hi Alex, very interesting video, which elements of this design would need to be adapted for use on 27Mhz

[@vk2prc978]

All exactly the same but use T200-6 toroid and tune to 11 meter band, you will end up with a considerably shorter coax capacitor. All good I'v done it.

[@cesarastiz9691]

Hi Alex, What´s the initial length of the coax you use to tune the coupler?

[@vk2prc978]

This question and many other can be found here in the comments, start with about 1 meter.

[@G1VNB]

Great video.will this work on other bands e.g. 17 meters 73 G1VNB

[@vk2prc978]

Replace the T200-2 with a T200-6 and tune for 20,17,15,10M simply tune the coax capacitor length. The higher the frequency the shorter the coax capacitor

[@garrykraemer8993]

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

[@vk2prc978]

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.

[@jdsnapp]

Thanks again Alex. Just wondering if 6 loops about 5 inch in diameter would do same as toroids?

[@vk2prc978]

As the power used increases so the efficiency of the RF choke must increase. Check out this site, has a great table illustrating RF choke efficiency. pd9z.com/rf-choke-build-your-own/

[@richardsmith7068]

Which type of ferrite toroid have you used for the feedline choke?

[@vk2prc978]

Look at the text below the video.

[@yo8rgj]

Hello, what kind of ferrite are you using for CMC ?

[@mikevhx5682]

Great informational video👍🏻

[@wawolff6085]

If only these guys would edit the audio quality! Difficult to understand this fine idea of a video.

[@vk2prc978]

If you don't like this video then don't watch it, better still, put your own up and send me a link so I can criticizes it. Do you think this a Hollywood production?

[@wawolff6085]

@@vk2prc978 What a nasty old man. I really wanted to be able to understand your words of wisdom.