CB Radio: Build a GainMaster HALFWAVE on a DX Commander Pole..Another detailed upload
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- Опубликовано: 13 авг 2020
- I built a home-brew GainMaster 5/8 wave a little time ago using using the best quality co-ax for the job and wow the antenna is unbelievable . So I decided to build the HALFWAVE version so I could compare the two (that video is to come). 20 mins detailed construction video
Mil spec RG58 for the main antenna body.
Pole: DX Commander (DX Commander )
More uploads to come...click that bell
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Cheers
Mike M0MSN 
Наука
I built this and it smokes. I threw away all my other antennas, nothing conpairs to this for preformance vs price and it is not a compromised antenna. I got $8 in this antenna. Ha Ha what a trip. SWR's reflected is almost undetectable.
i realize I am kind of randomly asking but do anyone know a good website to watch newly released movies online ?
@Jaziel Jaiden meh lately i have been using flixportal. Just search on google for it :P -houston
@Houston Brysen Thanks, signed up and it seems to work :) I appreciate it!!
@Jaziel Jaiden you are welcome :D
I just read your post, too bad it smokes, maybe try a little less power
Verry good job.I will make one soon , for my 11m cb radio.Thank you sir.
Again Mike, many thanks for what you do! Always helpful and informative videos. I enjoy your videos very much. Another 10/10 from me. 73 ;)
Awesome, thank you!
Nice work Mike. 73s nice and straightforward
What a brilliant little antenna been running skip from South Africa to EU even as far as Finland Thx Mike.
Thank you 👍
How about instead of using 8AWG copper wire (same as 10mm2), make the upper part with same coax, using its outer part shorted with inner? Isn't the diameter of the coax will give much more wider bandwidth?
Same as the Flowerpot vertical. I have Flowerpots on 10 meters, 6 meters and 2 meters. They perform very well and they are my antenna of choice for our local ragchew nets amongst the local clubs.
De WB2VUO here near Buffalo, NY
Another success Mike 👍🏻 You’ll be needing to order another reel of you-know-what soon 😮
Mike, very interesting antenna. I will test here, in Brasil. TKS. Best regards from Melson PU2KTQ.
how refreshing to see this video thanks mike i will have a go at this but it will have to be good to beat my 827 ron in oxford
Sirio 827 one of the best antennas ever for 27MHz. :)
Very good
👍👍
that’s cool my friend, … watching from Kentucky The Bluegrass State in The USA 🇺🇸
Parabéns amigo pela antena muito boa antena vertical
Just got a26mhz cb. Hope to get a 27mhz set too. Going to build this to use on em
Hi Mike, nice video there, my friend.
Hey, thanks
Brilliant thanks for vid
No problem 👍
brilliant as always and interesting de MIKE M1KEY M0FCG
Thanks Mike
Thanks, looking forward to see film to make antenna for 4 m (69 mhz) that we have in Sweden.
Tell me what bands you usually work on. I would find it a HUGE privilege to meet you on the band (11 or ham). After 35 years on 11, i just got my ham ticket. You have an inspiring channel, Mike, believe me. I just love the way you show the antenna building.
Thank you Kurt, always on 80m most nights, we 'll catch up some day...
The HW version some have stated handles power better than the 5/8. I can confirm this as I have owned both. The SWR on the 5/8 version likes to creep up when running power. Maybe the matching stub is the culprit. I had the 5/8 wave up for 8 years with no issues, until it got wacked by lightning. I now have the HW version and no SWR crawl when running power. Performance is about the same.
Yes it is the stub, that is one of the reasons for west flex the power handling.
Can I do that with a gama match and aluminum tubing with a choke at the bottom??
Could this be done for a 20 meter band antenna. It should be 10 meter long.
Yes but with 15 turns on 110mm former for the choke
I once build a TL2 and de SWR changed if the feedline was moved. So i wasn't impressed. Then build a Double Bazooka. I'm still using it on 11 meter. I made one for 40 meters too but i have no space around the home for such a antenna. However i tested it once when i was camping and it performed also very good. Since you are enjoying making coax antenna's you could try it as well just for fun and experiment.
I'd like to know your choke design as in how many turns and what diameter former..?
@@JAFO. 12 turns coax around 10cm. Beside that i used a fabric made ferrite choke.
@48pluto - sorry it took me a few extra days to get back to you, LOL, but you had about one turn too many on your 10 cm former choke.
- if you were to try it again with 11 instead of 12 turns on a 10 cm former using 66% RG8X or RG58 I think you'd have much better luck.
.
Now don't forget *_End effect_* meaning you want the bottom half to be the full 108", but the top needs to be 5% shorter so more like 102.625".
.
By now it might be a moot point but if you ever get the bug and want to try it again, give it a shot with 11T -;or you could use a 2.6" former and wrap 16 turns using 66% RG8X or RG58.
.
Mine works so well it's quite flat across both the 10 and 11 m bands and not hitting two to one until about 2 MHz bandwidth!
73
Nice construction and great video. This is actually a 1/4 wave coaxial dipole not a "1/2 wave antenna". Just as a 1/4 wave ground plane like a "Starduster" or the Italian equivalent consists of a 1/4 wave vertical element with 1/4 wave radials. If this was what is commonly referred to as a "1/2 wave antenna" the center conductor above where the shield stops would be twice as long i.e. 4908 mm or 16' 3". Nothing wrong with 1/4 wave antennas... they work well. There has always been confusion with radio operators and antenna manufacturers around "1/4 wave antennas" as they actually ARE 1/2 wavelength center fed (or very near center fed) antennas.... but in typical descriptions a "1/2 wave antenna" would be an end fed 1/2 wave radiator like a "A/S Mighty Magnum" or one of many other 1/2 wave end fed antennas. This Sirio copy and the original have a 1/4 wave radiating element and a 1/4 wave "image reflector". The 5/8 version has a 5/8 wave radiating element and SHOULD have one or several 5/8 wave image reflectors or else the coax shield will have common mode current on the outside and will act as the "image reflector". An easy and simple way to check for common mode current on the outside of the coax on any antenna installation is to simply place you hand near of around the feed line at various points... if the reflected power/S.W.R. changes then there is common mode current on the coax shield and this can distort the radiation pattern of the antenna/give false S.W.R readings as well as creating RFI in the shack and potentially local RFI to other devices in your home and neighbor's homes. We don't refer to a "J Pole" or "Slim Jim" as a "3/4 wave antenna" even though the main element appears to be 3/4 wavelength long. A J Pole is a 1/2 wave radiating element directly coupled to one leg of a parallel 1/4 wave matching section. The "matching section" is driven by equal out of phase r.f. currents so it does not radiate... just like ladder line or twin lead. The parallel 1/4 wave matching section with one unconnected stub is what causes the horizontal radiation pattern distortion of J Pole and Slim Jim antennas. J Pole antennas and all 1/2 wave end fed antennas have problems with common mode current on the coax and many use a Coaxial Current Choke like the Sirio antennas depicted in your videos use.
Sorry mate but you're just confused by center-fed vs bottom-fed. If installed vertically, this is most definitely a vertical *_1/2 wave center-fed dipole._*
The RF energy radiated from both the 1/4 wave center conductor above the cut coax shield and for 1/4 wave below it - ON the shield - adds up to 1/2 wave length, and is stopped by the choke,
- hence the need for a choke.
On a bottom-fed 1/2 wave the RF energy begins radiating at the bottom of the 1/2 wave conductor (radiator) with high voltage and goes up 1/2 wave, through the high current in the center of the radiator and achieving high voltage at the tip, then reverses back down 1/2 wave through high current in the center to high voltage at the base/feed point, thus completing the full 360° cycle or One wave length.
On a center-fed or this T2LT-style vertical - the RF begins radiating at the center feed point (or point at end of cut coax shield) as high current, travels up the radiator 1/4 wave to the tip where it achieves high voltage, then reverses back down 1/2 wave through high current in the center and to the bottom where it achieves high voltage at the choke, then back up 1/4 wave to high current at the center - for a 360° cycle or one wavelength.
*_BOTH are 1/2 wave antennas._*
A bottom-fed 1/2 wave can have a 1/4 wave height advantage - depending on construction & installation.
A center-fed has the advantage of a near perfect 50Ω feed point impedance, requiring no lossy or power limiting matching network.
73
*Edit:* I have never before heard the term: "Image reflector" - but it sounds like it would possibly often be heard in certain local areas on Channels 17 & 19. 😣
Hi Mike, I follow your videos on antennas because you know how to explain them very well, and sometimes I make them. It would be nice to know if this antenna could also be in 15, 20 mt band. My doubt is if there calculation for the choke on these bands
You can scale them up but size is an issue... the coil is a 1/4wave ;)
yes this coaxial dipole will work for any band as it is simply a 1/4 wave radiator with a 1/4 wave coaxial sleeve to make up the 180 degree mirror image reflector that the radiator needs. The choke calculations can be found on the internet for any frequency range and are not antenna specific, they are frequency specific but will still work to some degree even if not exactly correct. These coaxial sleeve antennas are very popular in commercial and Ham VHF and UHF antennas and usually do not require a common mode coaxial current choke as the sleeve portion resolves most of the common mode current on the outside of the coax feed line.
Interesting to see an alternative to the traditional T2LT 73
Cheers Tim
yes im going to build it
We really need a quarter wave length coaxial trap? I saw other version of this antenna with only 5 or 6 turns on a 10 cm diameter pipe 🥺, I'm confused 😁
@14KiloWhisky - it's actually a half wave choke, because it said a voltage node so it's a voltage choke not a current choke. So what you have to look at is about 2.6 in of former Plus the current is going all the way around the coax so you have to take the average of two halves equal to one hole or an additional point 2" so a total of 2.8 in * pi * 16 then divide that by the velocity factor and guess what, you've got a half wave inside which is 180° out of phase which tends to cancel - exactly what you want at that point.
hello, good video
It is not clear to me where to connect the 1.5 mm cable from the tip of the antenna???
Thank you
To the centre core of the coax.
Did you ever do a 1/2 vs 5/8 comparison?
BTW the stub on the 5/8 version, does that exist just to change the impedance back to 50ohm as you increased the length to 5/8?
no not yet, and yep pretty much.. :)
Thanks for the vid.Wouldnt it be easier to connect the cables with a connector just to easy adjust the lenghts?
Yes, absolutely, its only the cost that would increase
Have you tried 70358 / frequency = 1/4 wave in mm. G7FND
In theory then, just find a 1/4 wave x2 plus the matching and any band could be made? With Cal's new 60 ft pole maybe a 20 meter version could be mounted, and no radials needed? that would be an interesting build. I have an M2000 that will not do 20 meters, but it being 24 feet I wonder if a 20 version of this mounted off to the side of it could be done, again avoiding the radials issue. Just a thought, you make building these look too easy!! Thanks for doing all 3 versions!!
yep up or down scaling to suit the band. 😍
WHAT SIZE IS THE FORMER TO MAKE THE CHOKE?
Hi, have you tried comparing your 1/2 wave with your 5/8? If so, how much difference is there between the 2 antennas out at, say, 25KM?
yes, there is not a lot between them, the 5/8 wins
Hi Mike ' good video as per normal".I was wondering if you could' build one of these for lets say ' 15 meter's or 20 meter's or some other HF frequency ?. would be interesting to see if these could be adapted and what sort of performance you would get out of them ;) . cheer's Martin mw0cnd
Yes. Others have done this by scaling the dimensions. The only issue is of practicality. If you need a 7m pole for the 10m version you would need a 14m pole for the 20m version..
Hola me encantó su vídeo y me gustaría fabricar una antena,podría decirme de qué diámetro es la bobina?73/51
you make great videos on the subject of antenna construction 👍🏻 are the dimensions of the antenna that you show at the end of the video the perfect ones? 249cm
Yes, correct
Doesn’t the Gainmaster use a specific coax with a velocity factor for its design?
yes.
where do you get your so239 to crimp onto coax? Thanks
internet search eBay
Mike-M0MSN Thanks 73
Great vid Mike. Was there much comparison between the 5/8 and the 1/2 wave ?
Thats to come in a future vid, but the 5/8s is the clear winner :)
Maybe try a 0.64 wave like the Imax 2000. That would be an interesting video? cbradiomagazine.com/the-imax-2000-exposed/
Bren Wyatt M0RIJ food for thought
Hello Mike
Can you explain me how ti calculate the choke depending on the frequency?
In the T2LT 27MHz video make 16 turns on a 6.6 cm diameter. The total lenght is 331.75 cm, a long way from 277 cm???
Thank you 73 de i3qko.
Yes: the choke needs to be 1/4 wave length (1/3 on a 5/8 antenna or more)...I used 16 turns because I used the same former as with the 5/8 wave..
@@mike-M0MSN Can I use a different former, let's say 60-63 mm, while keeping the same 1/4 wave lenght diminished proportionally to the antenna ?
@@BASSLINEPFP yes
the common mode choke needs to be a specific impedance at the intended frequency of operation to stop or reduce common mode R.F. current from traveling down the feedline. There is a Ham's site on the internet that gives specifics.
Hi !
Q1
The cable is RG58 or H-155 ?
Q2
Is there an exact diameter of the cylinder on which to wind the cable, or is it only important how long the section is?
Q3
I would like to build it, but I don't understand the final length of the 3 sections. 2.49, 2.49, 2.77 meters? I would like to use it between 27,200 - 27,800 MHz, on classic CB frequencies, in USB mode
Thanks, regards
Did you ever manage to get hold of that heat shrink tape Mike?
HI Roly, No not yet, been up to my eyes the last 10 days.. :(
@@mike-M0MSN That's no excuse at all 🙄
Klasse Info Video gefällt mir sehr gut
73 de DE2TRF loc jo60el
Hi Mike ! I always enjoy and learn something from your videos, so thanks :) . Can I ask, what is the yellow pipe (?) you slip the DX pole over? I’m thinking to buy a basic 10m DX pole from Our Man for experimenting, getting struck by lightning etc.
The pole in the ground is a glass fibre decorators pole witch normally has a paint roller on the end :).
I want to recreate such an antenna.
BUT! I want to make the 2.52M top section of two aluminum tubes, because the whole thing should be as thin as possible to reduce wind load and optical reasons. I thought of taking two tubes with 6 and 4 mm diameter each, and 8 at the bottom.so I could slide the lower part of the coax into a GRP pipe.
Go for it!
hello Mike from IU8HDJ I would like to know if the multiplication at 0.93 must be done obligatorily I only understood that you got 249cm because you calibrated at 27,500 right?
The 0.93 to 0.96 is a correction factor due to the materials being used (VF)
@@mike-M0MSN thanks mike i knew 0.95 for copper and 0.85 for aluminum from what you tell me 0.96 is also fine
a 6m version would be nice...maybe even dual ones
More for the list.....
Would this work on. A thunder pole tx handheld. Please. AM FM uk. And eu and would it work on USB lsb if I ever get. One of USB lsb radio. If I ever do thanks
yep
Hi what CB radio coax would I need please to make this please. And. Would it swr in write
RG58 works fine
Hola,muy buen video explicativo de la HW,que me he decidido a montar una.
Tengo un mástil tescopico de aluminio y el cable va por dentro como la original y la bobina la voy hacer con un tubo de PVC 60mm.
Mi intención es dejarla fija como antena principal. Mi pregunta es si tendré problemas con las estacionarias y como corregirlas, Gracias y un saludo
Novato Español
Maybe yes, you will have to test it.
That pole you used what is it called
dx commander pole
Good evening Mike 73
Mike this is antenna don't have capacitor?
yep "No Capacitor" just a straight dipole. :)
@@mike-M0MSN Hi Mike. I am new to Radio and have found your videos very useful, many thanks. Please can you tell me what is the function of the capacitor is on the 5/8 you made? Thanks again.
great thou mike im gunna make that tomoz because my antron99 finished and have got 2 10m dx commander poles ill let you know how i get on m8. id love to see how it worked on ssb next time mate
well how it recieves
Hey Steven, go for the 5/8s Gainmaster version if you can, got great gain on the 1/2 wave..
@@mike-M0MSN have you got a video of it if so ill try it mike thanx
@@stevenaustin2860 ruclips.net/video/DLDdOepaq7k/видео.html
@@mike-M0MSN arr thanx very much your a diamond mike thanx mate it will save me a few quid because i was going to buy one thanx again mike 73 and stay safe m8 73 AND ENJOY YE RADIO
Nice work, but you are not done yet. this antenna needs lots more fine tuning.
I built one that has a bandwidth of 1MHz. That is, a swr lower than 1:1.3 over this area. The performance is significantly improved by changing the radiator to flexible copper wire of 10mm2.
Thanks for the input. :)
How about instead of using 8AWG copper wire (same as 10mm2), make the upper part with same coax, using its outer part shorted with inner? Isn't the diameter of the coax will give much more wider bandwidth?
Is this the 2 KW Version ?
73´s DH1KJ
LOL
Yesssss
Perfect for the DXers. and the newer channels. :-)) Did you cut it for 10Meters in the end or just work it out for 10?
Both!
anybody know 14 mhz version this antenna ?
that will be a long antenna
Простой вопрос : как вернуть заводские настройки? Ибо во всех других работает крайне погано.
Well I have now made both the 5/8 and the 1/2 wave, and the 1/2 wave is 2 s-points up compared with the 5/8! However, this is in hilly Welsh terrain. Not what I expected though!
Humm is that 2 points up on a known signal or on background noise? Interesting 🧐
Mike-M0MSN My friend who lives around 2 miles away with a few hills between us is now getting me on an S7 whereas he was only getting me on an S5 when I used the 5/8. I haven’t changed anything else at all. I think it could be because the antenna is actually higher off the ground relative to its size, because it is shorter and I am using the same height pole?
gtaguy235 OK, yep I think you are spot on, just go to show why we have so many different types of antennas. Thank for letting me know.
The "takeoff angle" or vertical angle of maximum radiation is different between a 1/4 wave and a 5/8 wave antenna. A typical 5/8 wave antenna has a lower "takeoff angle" and hence is better for DX because the lower angle extends the ionospheric propagation angle/distance. Higher angle = shorter hop/lower angle = longer hop. The higher angle "1/2 wave" (actually a 1/4 wave radiator) may give you better local coverage. Each and every antenna have their own merits and faults. It just takes experimentation to find out which works better for each individual situation.
@@juststeve7665 Hey Just Steve, you seem confused about RF. It's AC so there is a positive half and a negative half to the radiated wave-front. A 1/2 wave can be a 1/4 wave up and a quarter wave down - as long as both are in the same polarization (like a Starduster) but a true 1/4 wave GP would have a 1/4 wave vertical and one to four 1/4 wave radials in the horizontal - so since there's a 20dB separation in radiation performance between vert & horiz, you only see the radiation from the upper vertical 1/4 wave - if you're on a vertical receive antenna,
and that's why it will be 3dB down from a 1/2 wave like a center fed 1/2 wave Starduster, Ringo, A99, Proton99 and others only 18' or so long. When my cousin lost his mickey-mouse installation 1/4 wave GP in a windstorm and replaced it with a Starduster on the same mast that fell with his 1/4 wave on it, he went up about 1/2 to 1 S-unit to everyone, same height & coax.
Is 2047 mm or 2 metres and 47 ins
2047mm is 2.04M or 204.7cm or 81inches
hey mike the gainmaster is a 5/8 wave isn,t it lol but good stream m8
It’s both available as 5/8s and 1/2 wave versions.. . Lol
Aqui Robson do Brasil gostei da antena vó fazer uma aqui essa antena e pra falar mais local ou da pra falar dx também obrigado pelo trabalho
Obrigado
How meny meter is it
27MHz. 11M or antenna length is 7M approx
Do you sell these
sorry no. :(
¿ Puede contruirse con tubo de aluminio ?
Hola ,yo estoy haciendo una y la parte del tubo lo he solucionado económicamente,ahora me falta corregir si hay problema con la corriente estacionarias si tiene está antena y como se corrige,si me informan la solución te valdrá también a ti.
El mastín principal con das tubos de 1,80m(recoge hojas piscinas LEROY MERLÍN) y el reto de los tubos los tienes ahí también.
Mike I have the coil base for a gain master hf if you want it for free. For the new upgraded version.
That would be nice, yes please. :)
I calc'd 2.749m incl Vel factor for 27.2
You must have 120° not 180° in order to get a flat swr, a T2LT should be 74Ω or about 1.4:1 when resonant
@cedarridge3020 - your measurement looks pretty close for the bottom half but you have to take 5% off the top half for _"End effect*_ - unless you're going to put some kind of a capacitance hat on it.
Maybe I suck at math (I do actually) but a 66mm diameter bottle's circumference is 207,345 mm and at 16 turns gives you a length of 3317mm more or less, and not 2.77m?
No your math is good. You need a minimum of a quarter wave to choke(2.77) at this frequency, but as this version of the antenna is a 5/8 or 66% , 3317 is a better choke.
@@mike-M0MSN I thought this was a halfwave.
@@WillieJu again you are right, I should have checked the video before I made a comment, that said the choke coil is the same as the one I used on the 5/8 wave. Same thing though min 1/4 wave coil. Bla bla
@@mike-M0MSN Cool, I wanna build me one for my CB radio 27Mhz and put it up 11 or more meters.
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Belki bir gün senin güzel dilini öğrenirim 73