You got me with this one❗️ In the 80s I had 5/8 on CB and I was the King. As soon as the band was open I had stations piling up from all over the world and giving me phenomenal reports. Got my license 6 months ago and now I’m going to make one for 10 and one for 15. Thanks for helping me to do it😃 73 de HB3XBL 👍🇨🇭
CB 1/2 & 5/8ths are shorted at DC. They require no ground, using an L match means that you get the advantage of the true other half of the antenna and require a ground.
Well Colin you have convinced me to have a go at the 5/8th . The videos are very informative without a lot of hype. Just enough detail to allow all skills types (old hand to newbie’s) to understand and follow. Thanks again .
Thanks, yes I dont like hype. Antennas are very hard to prove whats good and what's not so I dont see the point in the BS. I do like this antenna and hopefully I can compare against the Moxon over the winter.
Made this antenna today, following your design closely. Worked wonderfully! I found the angle of the radials and height of the LC box moved the SWR around a bit. First contact was NL7V - Alaska, using 25W! I have the 12M Spiderbeams pole and am going to attempt 20M band by wrapping the wire around the pole, widely spaced to avoid inductance and just enough turns to still have a metre or two above the ground. By the way, I have also made your Moxon for 10M, it’s my favourite antenna. Thanks for all you do to help novice amateur radio operators like me. Best regards, Kevin M7XOM.
Excellent Kevin. You don't sound like a novice to me. My goal yes is to inspire others who dont yet have the confidence to build their own. On the Spiderbeam, I think you can buy the conversion sections to make it 14m.
@MM0OPXFieldRadio I get better results using 3 radials, the SWR is less sensitive to slope angle. I’m guessing it helps directivity too (if you want a more circular radiation pattern)? I really like this antenna, it’s very much a ‘tinker with’ thing you start to get a feel for how to adjust tuning resonance, SWR and RL. I wonder if traps would make it multi-banded? Today’s project methinks…
I use a 40 meter end fed half wave dipole as a vertical here at my house and it works fantastic. Managed to even get Bouvet on 30m CW with it and 100 watts. I like the simplicity of this and an gonna give it a go for 10 where my EFHW is a little lobey. 73 de W3OY Ray
That is Awesome Colin! I remember the 5/8's wave for 11 meters but like you said hardly anything about it in the Ham world. I will have to make one and maybe you and I can make it work for a contact!
Thanks Chuck. The matching network puts people off I think. Its a strange concept thay your wire length is fixed and you tune it otherwise. My 10m version is about complete and probably our best shot of making the trip. The guys on the east coast have a 30db+ advantage over you west coasters, we will make it happen though.
So i've seen the Gainmaster homebrews and they don't use GP's/radials, I'm certain it's almost built like a dipole in two halves, which you could argue is its radial as it is then terminated at the bottom with an air choke. They also add another section of wire, not to sure if it's classed as a matching stub or counterpoise. I've seen modelling where at ground level it beats every other antenna in it's class, but as soon as an EFHW is mounted the same height as the 5/8's at half a wavelength high they become almost very similar. I like the simplicity of your build, got me subbed!
There isn't a lot of info out there on radials for 5/8's. It has a low radiation resistance so would suggest it needs radials. It certainly will only help. Regarding height what matters is where the maximum current point is. On a half wave its half way up, on a quarter wave its at the bottom and on a 5/8 its 3/4 the way up. Get all antennas so the highest points are the same and there wont be much difference between the 3 IMO.
I agree. The 5/8 wave antenna is a good vertical antenna. It offers gain over 1/4 and 1/2 wave antennas 5/8 wave can be tricky to tune in comparison sometimes. Adjustability built in the system will help immensely Keep up the good work ! 73 de VO1DV
@@MM0OPXFieldRadio good stuff ! Keep up the good work ! From what I’ve seen so far on your Channel you have a neat job made of All your projects. Subscribed. Some of my projects are on my TH-cam channel including some antennas I have built and a few other projects as well. 73
Thanks for the video Colin. I bought the SIRIO TORNADO 5/8 last week,it's built for 11m but l extended the measurements a little and it works really well on 12m,1.2 swr with 4 2m radials,At the moment it's only 2m high.My best DX so far is Arizona 569 and Japan 559 pwr 100w. I want to do some experiments with the ground plane,increasing the radial length to 4m.The antenna has an Swr of 1.3 on 10m and works very well on that band also. 73s Rob G4WGR
Put 3 5/8 radials on and have 1.5 swr on 10,12 and 30m .Antenna 1 to 1@ 26.00. GREAT value for £60.00 at my local shop Kam Sat. Next job to improve coax.
I have used a 41' random wire vertical with 4 -16' radials up the Spiderpole with a 9:1 unun. I wondered why it worked so well on 20m and realized its a 5/8 wave there.
Well done, a great explanation. Not in any way criticising, but hopefully of interest, from memory a shade over 62.5% of a wavelength can eek out a tiny bit more low angle gain. I think in the region of 64% is slightly better, probably nit-picking. and of course it depends on the installed height and the angle you are seeking gain at. Regarding the coil in your matching unit, if you had put an extra turn on you could fine tune the inductance by prising the turns apart slightly. A great project, and well described, something you might find interesting to compare it with is a 1/4 wave for the same band with the top at the same height and a few tuned radials coming down at angles from the feedpoint, it might surprise you. 73
I agree with last comment. The 5/8 wave can beat the 1/4 and 1/2 wave when their feed points are at ground level but when the top of them are at the same heigth their performances are quite close because their maximum current distributions are at the same heigth too. I´m using raised center-fed vertical dipoles (to avoid constructing and using 64 to 1 transformers) on 20m and 15m with their bottoms several meters above ground and they are great performers. 73 de LU3HIP César.
Great build colin and excellent explanation on how to build it..I much prefer monoband antennas and raised radials in the real world works best for me! 73 Gm4zji Chris
Hi, thanks for this. I think there can be a hazard using (sloping) quarter-wave radials, as their currents are out of phase with the main radiating current in the vertical radiator. As yours are almost horizontal, that might not be a big problem, but could be worth modelling to see whether there is a compromise in the low-angle performance, and possibly a vulnerability to extra sky-noise from a high-angle lobe. 5/8-wavelength radials probably don't have this issue, if they are strictly symmetrical. Hope that helps! 73, Tim
@@MM0OPXFieldRadio Thanks colin for that much appreciated. Just going off the topic.49.1 end fed sloper half wave 7mhz .10metres to 6 metres, is it better to have the unun at 10 or 6 metres in your opinion?
Great work! It's handy to know what to expect as you increase your tower hieght for a given frequency. If you have the magic length of tower for a 1/4 wave at the operating frequency you should see about 30 ohms (R) on your Rig Expert. If it's on the short side you will see a value of (J) that is (-) or capacitive reactive. I giggle when hams think sticking coax directly on is ok..... Your SWR meter will be all happy.... But technically your aren't bang on as the SWR suggests (if you were it would be reading about 1.5:1). You are really off a bit to get the 50 ohms needed and you are presenting a complex load to the TX it's not pure resistive. Some understanding of smith charts helps explain what is going on here. As you magically wave your wond and the tower hieght increases the R steadily climbs. Now you are also seeing (J) in a + value as its not inductive reactive. Just above a 1/4 wave is the real 50 ohm (R) point but now you have a stack of J to get rid of. As you continue up... You now see R in the order of 800 ohms and (J) flips once again back to Capacative reactive. This is just in front of the 1/2 wave point. Past this point you start to get minor top lobes appearing and the gain of the 1/2 wave over the 1/4 wave is starting to be lost. This assumes you want maximum push along the ground like an AM station does. You want this too if you want to throw as far as possible over the horizon. You want low angle take off. You magic wond gets waved once more ant we just past the 1/2 wave now we near the 5/8.... The R drops off a cliff pretty fast here as we keep increasing tower hieght. But we cross a 75 ohm point and this is where its used. You do have a stack of J to get rid off.... But you also have a higher take off angle for your trouble. You will have more EMF in the air for all the money spent on the bigger tower. But is it worth it? Yes tuned is always better.... but any length will radiate... its about effectively feeding the power to it... I'm a tad concerned you have the C on the wrong side of the coil.... In an L network the shunt leg is on the higher R side of the series leg. IF you are truly on the 5/8 point you should be seeing R 70 with J being quite large. For a ground mounted aerial. Cheers great work! 73's from down under VK land.
Love the insight. I did have the cap connected to the other side of the coil bit match was way off. If was then pointed out to me i had it on the wring side. When i connected it this way all was good and as per SimNEC calcs. My raw values before matching were R82.3 and J-382.6. Dont think these values are far away from your prediction. I've likely got some interaction in my garden too.
@@MM0OPXFieldRadio I use MMANA for aerial modeling... It has a tab for matching tools under HF Components. I can't recall the exact reason why the shunt goes on the hi impedance side of the series leg. Punching in the numbers you supplied about it definitely draws the shunt leg on the hi side (aka the aerial with 80 ohms). I've watched the video a few more times you have it correct. If i can find the chart that shows the response curves for different tower hieghts i'll share it. 73's
A little about me.... I look at aerials with the mind set I need to get as much effiency as possible from a short stick. It needs to do this with real world AM power 24/7.... 30% duty cycle doesn't enter my world. I've carved out a niche business here looking after people's MF NAS services in Australia. We are lucky to be able to have 400w licenses on 1611 to 1701khz for special purposes. In getting these running several enlist the help of the local ham..... and needles to say some Myths need to be corrected when I get asked to help! BTW using the coax's Capacitance as a high current Cap.... Brilliant! Done that a few times myself. High power Vacuum Caps used in Broadcasting ATU's are not cheap. 73's
can omit the l/c match and just use the tuner in your radio and get the same performance. The l/c match is just to give a match to your coax and in to your radio
Sorry but thats rubbish. 2 things. 1 - the tuner in your radio will unlikely be able to match this as the SWR is something like 20:1. 2 - use an external tuner in your shack and you have massive losses in your coax. Place a tuner right at base of the antenna instead of the L/C match and you will omit the coax losses and have a decent performing antenna.
@@MM0OPXFieldRadio not rubbish, you have not seen my tuner and it is nowhere near a 20:1 swr.I have done it, yes there are some losses but it worked. I have even bypassed the unun on an efhw for 80 and up and an it on 160m and tuned it on every band above with an antenna tuner and made contacts. It sems that you forget, antennas are only based on theory. If something does not fit in you little box it is impossible. I though you were doing a great job in ur videos. I was wrong.
@@n0vty873 If your setup is working for you then best of luck to you, I have no interest is what anyone else does. If you want to make a statement then you need to base this on real data, let me provide you with some of that. At the calibrated feedpoint (no matching or coax skewing the SWR) the antenna parameters are R 82.1 and X -380.7 (I still have the analyser screenshots). This is an SWR of 38:1, go and do the calculation yourself if you dont beleive me. Your original comment "can omit the l/c match and just use your radio and get the same performance" is categorically wrong, thats fact. Just because an antenna works for you does not mean its working well? How do you define well? Remember even a dummy load will emit some RF leakage. If you tell me how long your coax is and what type it is I can calculate for you what your losses are. Not theoretical losses but real losses. Will you still make contacts? Of course you but dont you want your system to be as good as it can be?
I notice that the shield side of your coax capacitor is connected to the antenna terminal of the matching unit while the inner conductor is connected to ground. I would have done it the other way around, thinking that done your way there might be additional stray capacitance between the shield and ground which could vary it things moved. Is there a reason for doing it the way you did? David VE7EZM and AF7BZ
It should make no difference as it's not a polarised capacity. Electrolytic capacitors are polarised and can only go way, these have an indicator showing the polarity.
Have you considered building a 1 to1 common mode choke for noise reduction. I've found them to help with most all antennas. The TRX channel had one of the best and he was able to prove it was working.
I have built them and do use them with mixed results. Sometimes they work with RFI but sometimes not. Im a big fan of the GM3SEK chokes. Check them out if you haven't already. There isn't much better.
best way most effiecent way to feed an antenna at the end much better than any ferrite core and high power handling also buy wonder why you didnt fit a common mode choke as i would expect rf on the coax any reason ?
Theres no universal rule. Theres local rules, national rules etc for different countries. Here in the UK its 3m unless you apply for planning permission from the local council.
How did you determine which end of that 17pF coaxial wire capacitor to connect to the radials and which end to connect to the 5/8 wave cut wire? … or does that matter? VE3VVW
Good video Colin. I don't have a 15M antenna here -- but I do have a Spiderbeam pole supporting the end of my 80 OCF dipole -- so I'm tempted to try a 5/8 for 15M. The other possibility is a 1/2 wave vertical dipole. I might try both 🙂 73 Bruce G4ABX
Try the 1/2 wave center-fed vertical dipole. You´ll save the matching network and the radials. And the performance is quite similar when the top of both antennas are at the same height.
@@cesarastiz9691 I have portable 1/2 wave vertical -- the ProAntenna's I-Pro traveller. Its a great POTA antenna -- but a bit too heavy for back pack outings, being 'luggable' rather than 'carryable!' Perfect to take out of the car and set up nearby -- and the preformance is really good for something of such limited height. 73 Bruce G4ABX
Nice video. That is a killer antenna. So glad to see that you are using two elevated, resonant radials. About as efficient as it gets -- 97 to 99 percent efficiency of those elevated radials since they are high enough above soil in your yard that there is minimal waste of power going into that soil. de NK7B
Nice one Colin, The 17s are my favourite as well. Leaning towards 15s just now. Using a Sirio 827 with tuner and doing okay. Thanks for sharing, great work Rab MM7BVP
I mentioned this briefly in this video. I cut my wires first to final length then checked initial impedance without and matching. Remembering to calibrate the analyser to eliminate the coax. Can do a follow up if enough interest.
I rewatched the video Colin. All sorted. I made a 5/8 for 10m today using your method and it worked very well. (Heaps of DX contacts on FT8). I tuned the vertical element to where I wanted resonance.
@@MM0OPXFieldRadio thanks for the get back mate. I know it’s early their. 7:30pm here atm. Length didn’t worry me as much cause I’m thinking 10 or 11 m band. I have a theory…. But really not confident. Look forward to your theory and analysts. Ta mate. 👍🇦🇺🥃
A shunt can be in series or parallel depending how your trying to match. The capacitor deals with the reactivate component. It's an inductor in series and a shunt capacitor in parallel.
@@MM0OPXFieldRadio So here's a question for you if you needed to put the capacitor in parallel and the inductor in series, how would that be done? Actually that's the way you did it already but what if the opposite was needed where the capacitor was in series and the inductor would be in parallel, how would that be wired up?
matching a 1/2 wave with an autotransformer is so much easier that I have to say it's a push on which is best. if you create a lossy matching system for 5/8, any small advantage will disappear.
@@MM0OPXFieldRadio Thanks for the info. I heard that the ground has something to do with it, and ground-installed antennas can perform better in some situations. Thank you for your answer
@@polarbear5464 when your inland away from saltwater you want it up off the ground ideally as the ground will attenuate your signal. You can mitigate this somewhat with many ground radials. Over saltwater you want to use the ground as its so conductive.
Firstly I made the matching unit and tried dummy loads, one at 450 and then one at 3000 ohms. Big difference on the swr readings on my analyser as you would expect. Then erected the antenna on my 12m dxcommander pole. Resonate frequency for a low swr was around 17mhz. I chopped off about 75mm x 3 times off your suggested wire length and got the perfect sweet spot at 18.100 mhz at a swr of 1:1.2 Think it's been a success. Tried it on ft8 working like a charm. Thanks for your videos and imput. G6SBR.
Yeah a dummy load is only gives an indication. I'm glad you got it working. When I made the one for 10m I added 1 extra turn on thr coil and left the coax capacitor stub slightly long. This way I left the wire length and just spread the coil windings and trimmed the coax cap to tune. Either works and as long as the vertical is around 0.6 of a wavelength thats good.
A 5/8 is crap for some DX angles, fantastic low angle (9°-12°) but from ~20° - 45° they dip 7-9dB. I've been a .625 advocate for decades but often get out-talked in 10M DX land by lesser powered stations sporting simple cheap (junk) 16' 7/16 wave A99s because they love higher angle and ~20° they kill a 5/8. You'd be much better off going out to .66 for gain at the higher DX angle, plus it's a bit lower feed point impedance so easier to match, like a simple 75Ω 1/4 wave coaxial matching transformer for ~1.25:1 Plus you'll increase the capture area But the 5/8 T2LT design - (like the Sirio GainMaster) is really king of the hill.
I fashioned my 17M .625 from a Zero5 40M 1/4 wave vertical and added a 5-12" rod capacitance hat. Matched it using a single-turn tapped-ring. Works well for North State check-ins & local chit-chat Tuesdays.
A dipole at the same height as a 5/8 performs better than a 5/8; if a 5/8 were as good, all commercial radio stations would use stacked 5/8, but no, they use phased dipoles because they are more efficient.
Could you elaborate a bit more? When you say A dipole at the height is better? Are you talking about a vertical or horizontal dipole? Big difference there. The commercial stations, are you talking about VHF FM? I would be interested to see the data that says a vertical dipole outperforms a 5/8? Remember a FM broadcast starion isnt looking for DX. From what Ive read a if you have the top of a vertical dipole and 5/8 at the same height then performance is on par.
@@MM0OPXFieldRadio Hi, a vertical dipole at the same height, ( antenna tips) performs better than any 5/8. except over salt-water. a 5/8 works best at 1.5WL over ground, just like a dipole 2WL. Take a look at the Gain Master, it's physically a dipole, but a 5/8 dipole, due to it's symmetry.
You got me with this one❗️
In the 80s I had 5/8 on CB and I was the King. As soon as the band was open I had stations piling up from all over the world and giving me phenomenal reports.
Got my license 6 months ago and now I’m going to make one for 10 and one for 15.
Thanks for helping me to do it😃
73 de HB3XBL 👍🇨🇭
Awesome. Let me know how you get on. I'm going to try as well for other bands. Not an expensive antenna to build.
CB 1/2 & 5/8ths are shorted at DC. They require no ground, using an L match means that you get the advantage of the true other half of the antenna and require a ground.
Well Colin you have convinced me to have a go at the 5/8th . The videos are very informative without a lot of hype. Just enough detail to allow all skills types (old hand to newbie’s) to understand and follow. Thanks again .
Thanks, yes I dont like hype. Antennas are very hard to prove whats good and what's not so I dont see the point in the BS. I do like this antenna and hopefully I can compare against the Moxon over the winter.
Made this antenna today, following your design closely. Worked wonderfully! I found the angle of the radials and height of the LC box moved the SWR around a bit. First contact was NL7V - Alaska, using 25W! I have the 12M Spiderbeams pole and am going to attempt 20M band by wrapping the wire around the pole, widely spaced to avoid inductance and just enough turns to still have a metre or two above the ground. By the way, I have also made your Moxon for 10M, it’s my favourite antenna. Thanks for all you do to help novice amateur radio operators like me. Best regards, Kevin M7XOM.
Excellent Kevin. You don't sound like a novice to me. My goal yes is to inspire others who dont yet have the confidence to build their own. On the Spiderbeam, I think you can buy the conversion sections to make it 14m.
@MM0OPXFieldRadio I get better results using 3 radials, the SWR is less sensitive to slope angle. I’m guessing it helps directivity too (if you want a more circular radiation pattern)? I really like this antenna, it’s very much a ‘tinker with’ thing you start to get a feel for how to adjust tuning resonance, SWR and RL. I wonder if traps would make it multi-banded? Today’s project methinks…
I'm so relieved to see it's not another endfed short at DC. L match is probably the lowest loss way.
The coax as capacitance... Genius
Beautiful antenna and beautiful build. I have always loved 5/8 wave vertical antennas.
I use a 40 meter end fed half wave dipole as a vertical here at my house and it works fantastic. Managed to even get Bouvet on 30m CW with it and 100 watts. I like the simplicity of this and an gonna give it a go for 10 where my EFHW is a little lobey. 73 de W3OY Ray
Nice one Colin. That's a nice job. I like 17 m as well, especially on contest weekends!
Definitely Fraser 👍
In the 80s I had a 5/8 electronica special and all 3 that I had blew down , but it was brilliant while it lasted!
You got some amazing propagation too then.
Thanks for that I will give it a go, and try my small LC manual tuner.
Yes, a tuner at the base will do the same thing. Good luck.
That is Awesome Colin! I remember the 5/8's wave for 11 meters but like you said hardly anything about it in the Ham world. I will have to make one and maybe you and I can make it work for a contact!
Thanks Chuck. The matching network puts people off I think. Its a strange concept thay your wire length is fixed and you tune it otherwise. My 10m version is about complete and probably our best shot of making the trip. The guys on the east coast have a 30db+ advantage over you west coasters, we will make it happen though.
Another genius antenna build! More math is always good!!!
If I can do it, anyone can!
5/8 yes! Had a great VHF one years ago.
This video is inspirational to a new ham like me. I am inspired to make a 5/8 wave vertical 😊
Thats the idea, hindsight is a wonderful thing.
So i've seen the Gainmaster homebrews and they don't use GP's/radials, I'm certain it's almost built like a dipole in two halves, which you could argue is its radial as it is then terminated at the bottom with an air choke. They also add another section of wire, not to sure if it's classed as a matching stub or counterpoise.
I've seen modelling where at ground level it beats every other antenna in it's class, but as soon as an EFHW is mounted the same height as the 5/8's at half a wavelength high they become almost very similar.
I like the simplicity of your build, got me subbed!
There isn't a lot of info out there on radials for 5/8's. It has a low radiation resistance so would suggest it needs radials. It certainly will only help. Regarding height what matters is where the maximum current point is. On a half wave its half way up, on a quarter wave its at the bottom and on a 5/8 its 3/4 the way up. Get all antennas so the highest points are the same and there wont be much difference between the 3 IMO.
@@MM0OPXFieldRadio thank you for your lengthy reply 🧡
Top video Colin and an excellent explanation. I hope to see more soon. Alan 73
Me too, longer nights will help.
I agree. The 5/8 wave antenna is a good vertical antenna.
It offers gain over 1/4 and 1/2 wave antennas
5/8 wave can be tricky to tune in comparison sometimes.
Adjustability built in the system will help immensely
Keep up the good work !
73 de VO1DV
Thanks. I need to make some for other bands too.
@@MM0OPXFieldRadio good stuff !
Keep up the good work !
From what I’ve seen so far on your
Channel you have a neat job made of
All your projects. Subscribed.
Some of my projects are on my
TH-cam channel including some antennas
I have built and a few other projects as well.
73
Thanks for the video Colin. I bought the SIRIO TORNADO 5/8 last week,it's built for 11m but l extended the measurements a little and it works really well on 12m,1.2 swr with 4 2m radials,At the moment it's only 2m high.My best DX so far is Arizona 569 and Japan 559 pwr 100w. I want to do some experiments with the ground plane,increasing the radial length to 4m.The antenna has an Swr of 1.3 on 10m and works very well on that band also. 73s Rob G4WGR
Excellent. Try the 0.67 wave length radials if you have the space. Supposodly meant to be optimum.
Put 3 5/8 radials on and have 1.5 swr on 10,12 and 30m .Antenna 1 to 1@ 26.00. GREAT value for £60.00 at my local shop Kam Sat. Next job to improve coax.
I have used a 41' random wire vertical with 4 -16' radials up the Spiderpole with a 9:1 unun. I wondered why it worked so well on 20m and realized its a 5/8 wave there.
Exactly 💯
Thanks for another informative video. Looking forward to trying this one out!
Thanks Olly 👍
Well done, a great explanation. Not in any way criticising, but hopefully of interest, from memory a shade over 62.5% of a wavelength can eek out a tiny bit more low angle gain. I think in the region of 64% is slightly better, probably nit-picking. and of course it depends on the installed height and the angle you are seeking gain at. Regarding the coil in your matching unit, if you had put an extra turn on you could fine tune the inductance by prising the turns apart slightly. A great project, and well described, something you might find interesting to compare it with is a 1/4 wave for the same band with the top at the same height and a few tuned radials coming down at angles from the feedpoint, it might surprise you. 73
Thats brilliant feedback, thanks. I will impliment both for the next 5/8 I build.
I agree with last comment. The 5/8 wave can beat the 1/4 and 1/2 wave when their feed points are at ground level but when the top of them are at the same heigth their performances are quite close because their maximum current distributions are at the same heigth too. I´m using raised center-fed vertical dipoles (to avoid constructing and using 64 to 1 transformers) on 20m and 15m with their bottoms several meters above ground and they are great performers. 73 de LU3HIP César.
Colin, thanks for sharing. Very interesting software.
Definitely, so many useful features for us.
Great build colin and excellent explanation on how to build it..I much prefer monoband antennas and raised radials in the real world works best for me! 73 Gm4zji Chris
Thanks mate. Hopefully you can be field testing one long term soon.
Hi, thanks for this. I think there can be a hazard using (sloping) quarter-wave radials, as their currents are out of phase with the main radiating current in the vertical radiator. As yours are almost horizontal, that might not be a big problem, but could be worth modelling to see whether there is a compromise in the low-angle performance, and possibly a vulnerability to extra sky-noise from a high-angle lobe. 5/8-wavelength radials probably don't have this issue, if they are strictly symmetrical. Hope that helps! 73, Tim
I'm not sure about this. These radials are not radiating but used to reflect the signal.
Fantastic work Colin 👏
Thanks Mr Ape 👍
Thank you colin really appreciate your content. 10 metres vertical antenna at 21 feet with no radials is this really a 5/8 antenna
Well exactly. I think it needs the radials from the research I've done.
@@MM0OPXFieldRadio Thanks colin for that much appreciated. Just going off the topic.49.1 end fed sloper half wave 7mhz .10metres to 6 metres, is it better to have the unun at 10 or 6 metres in your opinion?
Great work!
It's handy to know what to expect as you increase your tower hieght for a given frequency. If you have the magic length of tower for a 1/4 wave at the operating frequency you should see about 30 ohms (R) on your Rig Expert. If it's on the short side you will see a value of (J) that is (-) or capacitive reactive. I giggle when hams think sticking coax directly on is ok..... Your SWR meter will be all happy.... But technically your aren't bang on as the SWR suggests (if you were it would be reading about 1.5:1). You are really off a bit to get the 50 ohms needed and you are presenting a complex load to the TX it's not pure resistive. Some understanding of smith charts helps explain what is going on here.
As you magically wave your wond and the tower hieght increases the R steadily climbs. Now you are also seeing (J) in a + value as its not inductive reactive. Just above a 1/4 wave is the real 50 ohm (R) point but now you have a stack of J to get rid of. As you continue up... You now see R in the order of 800 ohms and (J) flips once again back to Capacative reactive. This is just in front of the 1/2 wave point.
Past this point you start to get minor top lobes appearing and the gain of the 1/2 wave over the 1/4 wave is starting to be lost. This assumes you want maximum push along the ground like an AM station does. You want this too if you want to throw as far as possible over the horizon. You want low angle take off.
You magic wond gets waved once more ant we just past the 1/2 wave now we near the 5/8.... The R drops off a cliff pretty fast here as we keep increasing tower hieght. But we cross a 75 ohm point and this is where its used. You do have a stack of J to get rid off.... But you also have a higher take off angle for your trouble. You will have more EMF in the air for all the money spent on the bigger tower. But is it worth it?
Yes tuned is always better.... but any length will radiate... its about effectively feeding the power to it...
I'm a tad concerned you have the C on the wrong side of the coil.... In an L network the shunt leg is on the higher R side of the series leg.
IF you are truly on the 5/8 point you should be seeing R 70 with J being quite large. For a ground mounted aerial.
Cheers great work!
73's from down under VK land.
Love the insight. I did have the cap connected to the other side of the coil bit match was way off. If was then pointed out to me i had it on the wring side. When i connected it this way all was good and as per SimNEC calcs. My raw values before matching were R82.3 and J-382.6. Dont think these values are far away from your prediction. I've likely got some interaction in my garden too.
@@MM0OPXFieldRadio I use MMANA for aerial modeling... It has a tab for matching tools under HF Components. I can't recall the exact reason why the shunt goes on the hi impedance side of the series leg. Punching in the numbers you supplied about it definitely draws the shunt leg on the hi side (aka the aerial with 80 ohms). I've watched the video a few more times you have it correct.
If i can find the chart that shows the response curves for different tower hieghts i'll share it. 73's
A little about me.... I look at aerials with the mind set I need to get as much effiency as possible from a short stick. It needs to do this with real world AM power 24/7.... 30% duty cycle doesn't enter my world. I've carved out a niche business here looking after people's MF NAS services in Australia. We are lucky to be able to have 400w licenses on 1611 to 1701khz for special purposes.
In getting these running several enlist the help of the local ham..... and needles to say some Myths need to be corrected when I get asked to help! BTW using the coax's Capacitance as a high current Cap.... Brilliant! Done that a few times myself. High power Vacuum Caps used in Broadcasting ATU's are not cheap. 73's
Awesome, I'm literally an amateur at this game but learning all the time. Give it a go, nothing to lose.
Great many thanks for info, much appreciated GM4NNC
can omit the l/c match and just use the tuner in your radio and get the same performance. The l/c match is just to give a match to your coax and in to your radio
Sorry but thats rubbish. 2 things. 1 - the tuner in your radio will unlikely be able to match this as the SWR is something like 20:1. 2 - use an external tuner in your shack and you have massive losses in your coax. Place a tuner right at base of the antenna instead of the L/C match and you will omit the coax losses and have a decent performing antenna.
@@MM0OPXFieldRadio not rubbish, you have not seen my tuner and it is nowhere near a 20:1 swr.I have done it, yes there are some losses but it worked. I have even bypassed the unun on an efhw for 80 and up and an it on 160m and tuned it on every band above with an antenna tuner and made contacts. It sems that you forget, antennas are only based on theory. If something does not fit in you little box it is impossible. I though you were doing a great job in ur videos. I was wrong.
@@n0vty873 If your setup is working for you then best of luck to you, I have no interest is what anyone else does. If you want to make a statement then you need to base this on real data, let me provide you with some of that. At the calibrated feedpoint (no matching or coax skewing the SWR) the antenna parameters are R 82.1 and X -380.7 (I still have the analyser screenshots). This is an SWR of 38:1, go and do the calculation yourself if you dont beleive me. Your original comment "can omit the l/c match and just use your radio and get the same performance" is categorically wrong, thats fact. Just because an antenna works for you does not mean its working well? How do you define well? Remember even a dummy load will emit some RF leakage. If you tell me how long your coax is and what type it is I can calculate for you what your losses are. Not theoretical losses but real losses. Will you still make contacts? Of course you but dont you want your system to be as good as it can be?
@@MM0OPXFieldRadio I am just fed up with people pretending to be an expert
Very interesting and educational. Thank You
I notice that the shield side of your coax capacitor is connected to the antenna terminal of the matching unit while the inner conductor is connected to ground. I would have done it the other way around, thinking that done your way there might be additional stray capacitance between the shield and ground which could vary it things moved. Is there a reason for doing it the way you did?
David VE7EZM and AF7BZ
No particular reason David. I will try the other way around on my next build to see if theres any difference.
It should make no difference as it's not a polarised capacity. Electrolytic capacitors are polarised and can only go way, these have an indicator showing the polarity.
I'm pretty sure the capacitor in the video has no polarity.
Have you considered building a 1 to1 common mode choke for noise reduction. I've found them to help with most all antennas. The TRX channel had one of the best and he was able to prove it was working.
I have built them and do use them with mixed results. Sometimes they work with RFI but sometimes not. Im a big fan of the GM3SEK chokes. Check them out if you haven't already. There isn't much better.
best way most effiecent way to feed an antenna at the end much better than any ferrite core and high power handling also buy wonder why you didnt fit a common mode choke as i would expect rf on the coax any reason ?
No reason. I do have a few GM3SEK chokes when I feel nessesary.
Does anyone know where online I can find Laws in regards to Max Height for Ham Radio Antennas?
Or Know what the Max Height Legally is?
Theres no universal rule. Theres local rules, national rules etc for different countries. Here in the UK its 3m unless you apply for planning permission from the local council.
How did you determine which end of that 17pF coaxial wire capacitor to connect to the radials and which end to connect to the 5/8 wave cut wire? … or does that matter?
VE3VVW
It does matter. I did it the wrong way about first. The circuit diagram on SimNEC keeps you right.
Good video Colin.
I don't have a 15M antenna here -- but I do have a Spiderbeam pole supporting the end of my 80 OCF dipole -- so I'm tempted to try a 5/8 for 15M.
The other possibility is a 1/2 wave vertical dipole.
I might try both 🙂
73
Bruce G4ABX
Thanks Bruce. Give it a go and let us know how it is.
Try the 1/2 wave center-fed vertical dipole. You´ll save the matching network and the radials. And the performance is quite similar when the top of both antennas are at the same height.
@@cesarastiz9691 I have portable 1/2 wave vertical -- the ProAntenna's I-Pro traveller. Its a great POTA antenna -- but a bit too heavy for back pack outings, being 'luggable' rather than 'carryable!'
Perfect to take out of the car and set up nearby -- and the preformance is really good for something of such limited height.
73 Bruce G4ABX
Nice video. That is a killer antenna. So glad to see that you are using two elevated, resonant radials. About as efficient as it gets -- 97 to 99 percent efficiency of those elevated radials since they are high enough above soil in your yard that there is minimal waste of power going into that soil. de NK7B
Beleive it or not I have lost this somewhere in the mess of my garage. I need to find it and get it on the air soon.
Nice one Colin, The 17s are my favourite as well. Leaning towards 15s just now. Using a Sirio 827 with tuner and doing okay.
Thanks for sharing, great work
Rab MM7BVP
As long as your marking the contacts, that's all that matters.
Mono band antennas just work better, Great job!
Agreed!
Hi Colin this is an eye opener. Like you, I like 17m. Does your homemade capacitor in the LC unit use 50 ohm coax? 73 Rob G4RJS
It does Rob. This in particular is RG142 custom coax by DX wire.
Colin, I would like to know how you calculated the initial impedance values that you entered into the software. Perhaps a topic for another video.
I mentioned this briefly in this video. I cut my wires first to final length then checked initial impedance without and matching. Remembering to calibrate the analyser to eliminate the coax. Can do a follow up if enough interest.
@@MM0OPXFieldRadio well I’m certainly interested in a video in how you carried this out. THANKS.
I rewatched the video Colin. All sorted. I made a 5/8 for 10m today using your method and it worked very well. (Heaps of DX contacts on FT8). I tuned the vertical element to where I wanted resonance.
Excellent 👍
Nice one Colin! 👍
Thanks Tobias 👍
My Sirio GainMaster is also a 5/8 wave antenna but nothing near your vertical because it is a vertical dipole.
Can you clarify. Are you saying this is a vertical dipole and not a 5/8?
Rather than a matching unit could you go to the top of your pole and then come back down the calculated length ?
The wire is the calculated length. You dont make the wire a length to suit. You cut the wire right and then match it.
Thank you for another great video. So the LC match is only good for one band?
Correct. As a monoband it will ALWAYS have the edge (even of not to the ears) over a multiband.
Bravo. Great job!
Thanks Jay 👍
How would you go about doing a 5/8 over 5/8 of similar design ? Love your work. Keep it up . Cheers from down under 👍🇦🇺🥃
Honestly I've no idea but I will look into the theory. It would be too long for 17m but perhaps possible for 10m?
@@MM0OPXFieldRadio thanks for the get back mate. I know it’s early their. 7:30pm here atm. Length didn’t worry me as much cause I’m thinking 10 or 11 m band. I have a theory…. But really not confident. Look forward to your theory and analysts. Ta mate. 👍🇦🇺🥃
This is perfect really enjoyed this video By hooking it up this way is the inductor considered in series and the capacitor and shunt or parallel?
A shunt can be in series or parallel depending how your trying to match. The capacitor deals with the reactivate component. It's an inductor in series and a shunt capacitor in parallel.
@@MM0OPXFieldRadio So here's a question for you if you needed to put the capacitor in parallel and the inductor in series, how would that be done? Actually that's the way you did it already but what if the opposite was needed where the capacitor was in series and the inductor would be in parallel, how would that be wired up?
It all depends on the circuit configuration. Different circuits will need Different values. Download SimNEC and have a look yourself.
matching a 1/2 wave with an autotransformer is so much easier that I have to say it's a push on which is best.
if you create a lossy matching system for 5/8, any small advantage will disappear.
I do this too but quantyfy lossy? my autotransformer is 90% efficient on 20m. how lossy do you think the L/C match is?
I wonder if you could coil-shorten the vertical element? For those of us with shorter poles. Say what?
Yes, you could but you lose the benefit. Electricity it will be a 5/8 but physically smaller so efficiency will be lost.
@@MM0OPXFieldRadio Trade-offs everywhere you look.
Unfortunately yes. Cant cheat the physics.
Are you an electrician? You have heaps of junction boxes!!! 😆Great video!
If I was I would be a lot more knowledge. I do use an electrical wholesaler for those boxes which are good quality and very inexpensive.
Can you make same video for 27 mhz?
I will add it to my list and hopefully yes in the future.
Great job!
Thanks 👍
how high should my 5/8 antena optimally be placed? Thank you.
As high as you can get it. You ideally want it clear of obstructions so there is a clear take off. Just do your best.
@@MM0OPXFieldRadio Thanks for the info. I heard that the ground has something to do with it, and ground-installed antennas can perform better in some situations. Thank you for your answer
@@polarbear5464 when your inland away from saltwater you want it up off the ground ideally as the ground will attenuate your signal. You can mitigate this somewhat with many ground radials. Over saltwater you want to use the ground as its so conductive.
Wow you are way smarter than me. Nice build KM7Y Texas
Dont know about that but thanks 🙏
How much long your pole? Best 73 iu1rzx
10m
@@MM0OPXFieldRadio good projet i search for only 17 meter on my house I'm looking for one that can handle max 600w, do you build them and sell them?
how did it perform on transmit?
Very well. Mostly getting better reports than I was giving.
Does the antenna have a resistance of 450 ohms or 3000 ohms ?
Its roughly R82 and X-380. Big negative reactance to sort out.
Firstly I made the matching unit and tried dummy loads, one at 450 and then one at 3000 ohms. Big difference on the swr readings on my analyser as you would expect. Then erected the antenna on my 12m dxcommander pole. Resonate frequency for a low swr was around 17mhz. I chopped off about 75mm x 3 times off your suggested wire length and got the perfect sweet spot at 18.100 mhz at a swr of 1:1.2
Think it's been a success. Tried it on ft8 working like a charm.
Thanks for your videos and imput. G6SBR.
Yeah a dummy load is only gives an indication. I'm glad you got it working. When I made the one for 10m I added 1 extra turn on thr coil and left the coax capacitor stub slightly long. This way I left the wire length and just spread the coil windings and trimmed the coax cap to tune. Either works and as long as the vertical is around 0.6 of a wavelength thats good.
A 5/8 is crap for some DX angles, fantastic low angle (9°-12°) but from ~20° - 45° they dip 7-9dB. I've been a .625 advocate for decades but often get out-talked in 10M DX land by lesser powered stations sporting simple cheap (junk) 16' 7/16 wave A99s because they love higher angle and ~20° they kill a 5/8.
You'd be much better off going out to .66 for gain at the higher DX angle, plus it's a bit lower feed point impedance so easier to match, like a simple 75Ω 1/4 wave coaxial matching transformer for ~1.25:1
Plus you'll increase the capture area
But the 5/8 T2LT design - (like the Sirio GainMaster) is really king of the hill.
I fashioned my 17M .625 from a Zero5 40M 1/4 wave vertical and added a 5-12" rod capacitance hat.
Matched it using a single-turn tapped-ring.
Works well for North State check-ins & local chit-chat Tuesdays.
A dipole at the same height as a 5/8 performs better than a 5/8; if a 5/8 were as good, all commercial radio stations would use stacked 5/8, but no, they use phased dipoles because they are more efficient.
Could you elaborate a bit more? When you say A dipole at the height is better? Are you talking about a vertical or horizontal dipole? Big difference there. The commercial stations, are you talking about VHF FM? I would be interested to see the data that says a vertical dipole outperforms a 5/8? Remember a FM broadcast starion isnt looking for DX. From what Ive read a if you have the top of a vertical dipole and 5/8 at the same height then performance is on par.
@@MM0OPXFieldRadio Hi, a vertical dipole at the same height, ( antenna tips) performs better than any 5/8. except over salt-water. a 5/8 works best at 1.5WL over ground, just like a dipole 2WL. Take a look at the Gain Master, it's physically a dipole, but a 5/8 dipole, due to it's symmetry.
Tons or turns? It's like being Russian and talking to a Ukrainian... close enough.
Good stuff de gm0cqv
Thanks Brendan. Hope your well.