Thanks for the simple but informative information. I keep hearing about unun, balun, and the different ratios, but could not work out what went with what antenna. Good video, thankd.
Glad it was useful. I tried to keep it non-technical. You can deep dive into any of these devices if you want more info. There is lots of information out there. Cheers, Fraser MM0EFI
Very helpful! I've made an EFHW and it is working fine in inverted L for QRP, but I want to connect two other rigs to it and run 20W, but didn't know if I needed a balun, unun or choke, or all three! Tons of videos about each one, but nobody else out there explaining in high-level terms and comparing all three without getting lost in the weeds! THANK YOU!!! I think I get it now!
@@theradiorover Thanks, I was lucky with the callsign. My name is Ace and G0ACE had just come available for reallocation. My friends call it "Go Ace" ! LOL
great video, thanks for all the info. just put up a Rybakov at home with 14 raidials and was wondering if i should use a choke and now i know :D dont forget to MOT the landy. mine is due next month 73
Thank you for this Fraser… I learned a lot from this one… I keep my setup fairly simple with either a dipole or vertical…. So haven’t delved really much into this space. 😊
I thought you'd like it. I remember from talking to you before that you hadn't really delved into this area. It can be confusing abd there's a lot of inaccurate information out there. That’s why I kept the video high level.
Very informative Fraser. A great introduction to this mind boggling subject for a confused M7 like myself. Bite size information. Perfect thanks - M7MDO
@@theradiorover my questioning was the whole 9:1 64:1 49:1 unun .seems like the real difference is how many ohms they can knock down to 50? I built my first end fed yesterday and Im very happy with how it works and tuned up.
Cracking video Fraser. Although I’ve learned a bit about antennas I’m thinking back to when I first started and this would of been so informative so will really help those just starting out. Nicely explained and not too complicated. Thanks for taking the time to show the different antennas as well. 73 MW7WDP
Glad you enjoyed it! Didn't want to be teaching people to suck eggs, but I read so much incorrect information in social media etc about UnUns and baluns. I've been itching to do this video for months!
Good overview and to the point, Fraser! If you're using an EFHW, where the coax is part of the system, even with QRP, it may be necessary to use a choke/CMS. This depends also on the environment, the band you're on and how well the radio copes with HF (mostly a problem with the microphone input). A choke or CMC never hurts, apart from the additional weight to carry 😉 73 Stephan
Hi Stephan, You are the EFHW expert and I value your opinion on this. The short link I use in the video is my QRP choke. I try to use it with the EFHW 100% of the time, although when I've forgotten, it has been OK. I often forget to use it with my 41'and 84' randoms and haven't had any issues. I guess my kx2 and mic. combination isn't getting upset by it. Cheers, Fraser
@@theradiorover Thanks Fraser and yes, if it works with your KX2 without choke, then no need to worry about. My FT-818 is also less sensitive than my TX-500, but the Yaesu outputs less power and has no audio compressor. In this case, it's a bit like comparing apples and pears, hi. 73 Stephan
Hi Fraser excellent video,really enjoy this subject ,now it has got me thinking what about The shortwave listener would any of this benefit us I have about a 61 ft long wire in the back garden .Thanks for sharing all your stuff with us Best Regards Tim
Hi Tim, A tuned antenna will receive better. Whether that is through an antenna tuner or through being resonant. I use a W3EDP at home and the RX goes up massively after I hit the tune button on my ATU. Do you use a tuner with yours? 58' may work better for you! Happy experimenting. 😃 Cheers, Fraser MM0EFI
@@theradiorover Hi Fraser, thanks for the speedy response & yes I do use an ATU. However, I always wonder.... could it be better /can I do better. I’ve been putting up various types of long wire, trying to get the perfect listening antenna 🤪🤪 Thanks for your advice, Tim
Very instructive video, thanks. I'm trying to source ununs where I live (France) but these aren't available anywhere. I can only order them from the US or the UK with eye-watering shipping fees and import taxes. Baluns, however, are easy to find. So my question is: would using a balun with the same ratio instead of an unun on an EFHW or random length antenna work, possibly needed more tuning on the transceiver, or not at all?
Hi Alain, Glad you found the video interesting. 1. For an EFHW you must use a 49:1 or 64:1 un-un (auto-transformer). This is because of the very high (~3000R) impedance at the feedpoint. 2. For an end fed random wire, as long as it is one of the documented lengths that work, you may not need anything at all. Eg a W3EDP will have 3:1 SWR or less on most bands. Your tuner could handle this. 3. Buy a torrid and some magnet (enamelled) wire and try winding a 9:1 yourself. It is simple. The Radio Prepper did a good video on the subject. Hope this helps, Fraser MM0EFI
Use type 43 or type 31, based on your needs. There are charts available on the Web. Eg here: www.google.com/imgres?imgurl=https%3A%2F%2Fi0.wp.com%2Fwww.karinya.net%2Fg3txq%2Fchokes%2Fchoke_impedances.png&tbnid=jpdp60n4yCBnpM&vet=1&imgrefurl=https%3A%2F%2Fpa3hho.wordpress.com%2F2014%2F02%2F21%2Ffair-rite-toroids%2F&docid=BePHMtPiq4q7uM&w=670&h=722&source=sh%2Fx%2Fim%2Fm4%2F2#vhid=jpdp60n4yCBnpM&vssid=mosaic
Current baluns operate by forcing equal currents on both balanced lines, effectively eliminating common-mode currents, so ideal for a CM choke or a ½ wave dipole. Voltage baluns force equal voltage on each balanced line; this is ultimately a better fit for impedance matching applications. Hope this helps 😊👍
I want to build the 3 wire version (T3FD). Let's say I use a 1000 ohm termination resistor. There seems to be disagreement about the balun. Can you explain how to choose a balun ratio of 9:1 vs 12:1 vs 16:1?
Nice video Fraser. Apart from a 1 to 1 choke I always use resonant monoband vertical antennas, so no need for there others. My very old ham mate always told me, the less bits and bobs between the rig and ant the better hi, so I've stuck to that for 30 years. 73 zl3xdj
I'm with you on that one Brian. You do a great job with your verticals. Many portable antennas are a compromise though and end feds seem to be gaining in poloparity. 73, Fraser MM0EFI
@@theradiorover yes I am lucky to have a good take off and iam hoping to get my qcx mini to the beach on Wed evening, see if I can get 10000 miles plus with 5w. Being on the right band at the right time is my secret, I only ever work the greyline. Best wishes my friend.
I made my first dipole without using a balun, however I have a 1:1 current choke at the radio end. Is this the same thing as a bulun? and is the placement of it at the radio, instead of the antenna feedpoint a problem? Thanks
In a perfect world, with a dipole above perfect ground and no buildings nearby etc, you would have equal currents which cancel out in the feeder. This is rarely the case and some current will flow on the outer skin of the coax back down towards your radio. For QRP you don't need anything, however if you plan on running a bit of power then a common mode choke near the radio is a good idea. A 1:1 balun can be used to help match the BALanced dipole legs to the UNbalanced coax feeder. Belt and braces using both really.
Great, Great Video!!! I'm a new ham to HF. been messing around with VHF&UHF for years but not so much HF. Just got a QRP radio Xiegu x6100, It's going on three weeks now trying to configure a HFJ 350m antenna to work with it (No Luck) All I get on every band is harmonic tones and static. I have a 1:9 Balun coming in tomorrow (Saturday) from Amazon. Was wondering if you have any videos connecting a Balun that shows best setup for 1:9 Balan. Meaning counterpoise, configuration amounts of radials & length of redials? The radio is fine (no damage, new) As last week I took it to a park setup only two counterpoises about 18 feet off a 1:1 balun type dipole antenna I put together (have no idea what I'm doing) but a great deal of magic happened on 6m, 10m & 15m. The harmonic tones turned into voices. Could not get out of the US but did achieve under 400-mile contacts. As a new HF operator, just looking for hands on specs showing setup of balun, placement of balun, & wire length of counterpoise, along with amount of counterpoise cables in a pattern that would do better than 400 miles. Thanks again for above video!!! Any help would be appreciated. 73 for now. (My radio does have antenna tuner & SWR adjustment meter on it)
Brilliant! Well done for getting out there and experimenting, really well done. That's what it is all about. You have lots of stuff going right: 1. Using a random wire with a tuner. 2. 1:9 to help tuner get a match. So, in the video you'll see I list random wire lengths. All of these will work with a 17' counterpoise laid under the antenna radiating wire, or even out to the side if you can't manage. Arrange your radiating wire as an inverted V over a branch or mast, even 5 metres or yards for the apex will do. It will also work as a sloper. Now the radiation pattern will vary by band, and it won't be as good as a resonant antenna cut for a band, however when the bands are open, you will get some nice surprises, especially on the higher bands through the day. I use 41'and 17'. I also use 84' and 17', which is a W3EDP. You can go as low as 25' or 19' but you'll not get 40 m with that length. As for videos, you see me work a pile up in my Ulva Island videos from last November. I go over the mast arrangement and you can see the antenna goes to the Un-Un and straight into the radio. With QRP there isn't the need for a choke. As for your question about more radials. Well I wouldn't bother for a random. They may help with a tuned antenna however radials on the ground behave very differently on rocks, wet grass, dry earth etc. If you want a resonant antenna with radials, then a vertical with elevated radials works best. See my video about a simple dx 20 m wire. Hope this helps! Ask away if you need more help. 73, Fraser MM0EFI
Thanks Fraser. I've recently started to do activations. I've been subscribed for some time but couldn't find a video where you show the full antenna setup procedure for a linked dipole on a summit. Would you consider including the full pole/antenna erection in an upcoming summit video? There's lots of advice from other channels on how to do it on a perfectly flat, open, grassy space but very little on a rocky summit with limited space and an abundance of wind. I'd love to learn from your experience. Phill - VK7ID
Hi Phil, Good to hear you're getting out. It will soon be VK to GM summit to summit season! So, we'll need to get up in a hill for that. Here's a video I did a while back, but I will do another one in the next month or so. ruclips.net/video/vS5zwNagKUI/видео.html
@@theradiorover "A wee swally", love the accent! Thanks so much, very much appreciated. I've progressed from a 9m fishing squid pole and a 4 band HyEndFed portable EFHW to a SotaBeams 6m pole and 20/40 linked dipole saving lots of weight, making setup much easier, and eliminating RF feedback into the radio/mic. I see you use the "layout the dipole then come back one metre" method. I'll be sure to give that a crack!
Fred, No that is not correct. They all do different things. The 49:1 is for an EFHW and is very necessary. Consider it part of the antenna. The radio should not need a tuner. The 9:1 is for a random. You need a radio with a tuner or an external tuner. The tuner may get a match on the random without the 9:1, so this one may not be necessary. The balun for the centre of the dipole is not necessary for QRP. The choke isn't necessary for QRP but is advisable as it will help keep RF out of your radio, mic. cable, and mic. which could affect your tx audio. Hope this helps, Fraser MM0EFI
Thank for that Fraser. I just started using a KX2 for SOTA and unbalanced aerials. Given that the Kx2 will tune almost anything do you use an unun or choke with yours? Dave Ei3ixb
Dave, for QRP I don't always use a choke., mainly when I forget with my EFHW, or when the antenna is connected directly to the radio or the 9:1, 49:1 is straight to the radio. My recent balun video describes this. Also check out the bicycle portable one, where I plugged the EFHW straight into the kx2 because I forgot the coax. 73, Fraser MM0EFI
So for a common mode choke, what would be the preferred ferrite mix, number of turns, and type of wire (coax or 2 strands of teflon wire) for maximum attenuation at 27 mhz? I have a Solarcon 99 that seems to be radiating from the feedline even with an "ugly" balun at the feed point. Everything is sufficiently grounded.
Air core should work fine at 28 MHz. Have a look at this... www.karinya.net/g3txq/chokes/ The definitive work on chokes. The table has been replicated many times. 73, Fraser MM0EFI
Why only endfed, random wire, and dipole antennas. Why not verticle and yagi antennas also? I am a bit confused about that as most videos address EFHW antennas when talking about UNUNs and chokes.
Hi George, The same rules apply. Eg: if a vertical is an EFHW or random, then use the same type of transformer. A ¼ wave vertical with ground planes doesn't need anything, but it is always a good idea to place a choke in the feed line with any antenna. A yagi is just a dipole with added reflectors, so the same rules apply. I hope this helps. The video was not supposed to be too technical, instead it was designed to be an overview of which types of device to use with different types of antennas. 73, Fraser MM0EFI
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Well done.
Thank you!
Thanks for the simple but informative information. I keep hearing about unun, balun, and the different ratios, but could not work out what went with what antenna. Good video, thankd.
Glad it was useful. I tried to keep it non-technical. You can deep dive into any of these devices if you want more info. There is lots of information out there.
Cheers, Fraser MM0EFI
@@theradiorover Non technical is all us neanderthals need just to get a piece of wire in the air 🙏🙏🫡🫡🫡
@beaver3501 HaHa! Yes. 😁
Very helpful! I've made an EFHW and it is working fine in inverted L for QRP, but I want to connect two other rigs to it and run 20W, but didn't know if I needed a balun, unun or choke, or all three! Tons of videos about each one, but nobody else out there explaining in high-level terms and comparing all three without getting lost in the weeds! THANK YOU!!! I think I get it now!
That's great to hear! Good luck with your antenna experiments.
73, Fraser MM0EFI
I'm returning to amateur radio, so this was really useful to me and very well explained. Thanks for taking the time to make this video.
Thank you! Glad you found it useful. Do you have a callsign?
73, Fraser MM0EFI
@@theradiorover Hi Fraser, yes, my callsign is G0ACE and I have a page on QRZ which needs updating! Thanks again for your hard work.
Cool callsign. Good luck with your endeavours. Have fun 👍
@@theradiorover Thanks, I was lucky with the callsign. My name is Ace and G0ACE had just come available for reallocation. My friends call it "Go Ace" ! LOL
great video, thanks for all the info. just put up a Rybakov at home with 14 raidials and was wondering if i should use a choke and now i know :D
dont forget to MOT the landy. mine is due next month
73
The Landy MOT ran out. Thankfully I have four others 🙈
Great video. You do a wonderful job explaining the difference between all these options and when to use them. Thanks for sharing.
Glad you found it useful and relevant!
Cheers, Fraser MM0EFI
Thank you for this Fraser… I learned a lot from this one…
I keep my setup fairly simple with either a dipole or vertical…. So haven’t delved really much into this space. 😊
I thought you'd like it. I remember from talking to you before that you hadn't really delved into this area. It can be confusing abd there's a lot of inaccurate information out there. That’s why I kept the video high level.
@@theradiorover absolutely.
Very informative Fraser. A great introduction to this mind boggling subject for a confused M7 like myself. Bite size information. Perfect thanks - M7MDO
Martin, Glad you found it useful. Just don’t ask me to go into any more theory or detail!
Best explanation iv heard , Thank you for sharing your knowledge and time.
Thanks. I like to keep it simple!
Cheers, Fraser MM0EFI
@@theradiorover my questioning was the whole 9:1 64:1 49:1 unun .seems like the real difference is how many ohms they can knock down to 50? I built my first end fed yesterday and Im very happy with how it works and tuned up.
@Kc3vhr excellent. I have two. One has a 64:1 and is slightly (5") shorter. Both work well and I've worked GM-USA on 10m, 15m and 20m ssb with them. 😁
Cracking video Fraser. Although I’ve learned a bit about antennas I’m thinking back to when I first started and this would of been so informative so will really help those just starting out. Nicely explained and not too complicated. Thanks for taking the time to show the different antennas as well. 73 MW7WDP
Glad you enjoyed it! Didn't want to be teaching people to suck eggs, but I read so much incorrect information in social media etc about UnUns and baluns. I've been itching to do this video for months!
Good overview and to the point, Fraser!
If you're using an EFHW, where the coax is part of the system, even with QRP, it may be necessary to use a choke/CMS. This depends also on the environment, the band you're on and how well the radio copes with HF (mostly a problem with the microphone input). A choke or CMC never hurts, apart from the additional weight to carry 😉
73 Stephan
Hi Stephan, You are the EFHW expert and I value your opinion on this. The short link I use in the video is my QRP choke. I try to use it with the EFHW 100% of the time, although when I've forgotten, it has been OK. I often forget to use it with my 41'and 84' randoms and haven't had any issues. I guess my kx2 and mic. combination isn't getting upset by it.
Cheers, Fraser
@@theradiorover Thanks Fraser and yes, if it works with your KX2 without choke, then no need to worry about. My FT-818 is also less sensitive than my TX-500, but the Yaesu outputs less power and has no audio compressor. In this case, it's a bit like comparing apples and pears, hi.
73 Stephan
@@PortableRadio Apples and Pears! Absolutely. Unless in a laboratory, it is extremely difficult to predict what will happen.
Hi Fraser excellent video,really enjoy this subject ,now it has got me thinking what about The shortwave listener would any of this benefit us I have about a 61 ft long wire in the back garden .Thanks for sharing all your stuff with us Best Regards Tim
Hi Tim, A tuned antenna will receive better. Whether that is through an antenna tuner or through being resonant. I use a W3EDP at home and the RX goes up massively after I hit the tune button on my ATU. Do you use a tuner with yours? 58' may work better for you! Happy experimenting. 😃
Cheers, Fraser MM0EFI
@@theradiorover Hi Fraser, thanks for the speedy response & yes I do use an ATU. However, I always wonder.... could it be better /can I do better. I’ve been putting up various types of long wire, trying to get the perfect listening antenna 🤪🤪
Thanks for your advice,
Tim
Great presentation. Cheers from the burbs of Chicago. 👍
Glad you found it useful Kurt. Thanks for the feedback!
Cheers, Fraser MM0EFI
Very instructive video, thanks. I'm trying to source ununs where I live (France) but these aren't available anywhere. I can only order them from the US or the UK with eye-watering shipping fees and import taxes.
Baluns, however, are easy to find. So my question is: would using a balun with the same ratio instead of an unun on an EFHW or random length antenna work, possibly needed more tuning on the transceiver, or not at all?
Hi Alain, Glad you found the video interesting.
1. For an EFHW you must use a 49:1 or 64:1 un-un (auto-transformer). This is because of the very high (~3000R) impedance at the feedpoint.
2. For an end fed random wire, as long as it is one of the documented lengths that work, you may not need anything at all. Eg a W3EDP will have 3:1 SWR or less on most bands. Your tuner could handle this.
3. Buy a torrid and some magnet (enamelled) wire and try winding a 9:1 yourself. It is simple. The Radio Prepper did a good video on the subject.
Hope this helps, Fraser MM0EFI
Thanks for the informative video! Just one question, for the choke, what’s the best toroidal to use? Thanks
Use type 43 or type 31, based on your needs. There are charts available on the Web. Eg here:
www.google.com/imgres?imgurl=https%3A%2F%2Fi0.wp.com%2Fwww.karinya.net%2Fg3txq%2Fchokes%2Fchoke_impedances.png&tbnid=jpdp60n4yCBnpM&vet=1&imgrefurl=https%3A%2F%2Fpa3hho.wordpress.com%2F2014%2F02%2F21%2Ffair-rite-toroids%2F&docid=BePHMtPiq4q7uM&w=670&h=722&source=sh%2Fx%2Fim%2Fm4%2F2#vhid=jpdp60n4yCBnpM&vssid=mosaic
How about current and voltage baluns? When you say balun do you men a current balun? Thanks for a great video. 73 SM6YEC
Current baluns operate by forcing equal currents on both balanced lines, effectively eliminating common-mode currents, so ideal for a CM choke or a ½ wave dipole. Voltage baluns force equal voltage on each balanced line; this is ultimately a better fit for impedance matching applications.
Hope this helps 😊👍
This is so informative. Thanks, Fraser!
I'm glad you enjoyed it. Thank you so much for supporting my channel. 🙂
73, Fraser MM0EFI
I want to build the 3 wire version (T3FD). Let's say I use a 1000 ohm termination resistor.
There seems to be disagreement about the balun. Can you explain how to choose a balun ratio of 9:1 vs 12:1 vs 16:1?
I'm not familiar with that design, however a quick Google reveals that 9:1 provides a good match.
Nice video Fraser. Apart from a 1 to 1 choke I always use resonant monoband vertical antennas, so no need for there others. My very old ham mate always told me, the less bits and bobs between the rig and ant the better hi, so I've stuck to that for 30 years.
73 zl3xdj
I'm with you on that one Brian. You do a great job with your verticals. Many portable antennas are a compromise though and end feds seem to be gaining in poloparity.
73, Fraser MM0EFI
@@theradiorover yes I am lucky to have a good take off and iam hoping to get my qcx mini to the beach on Wed evening, see if I can get 10000 miles plus with 5w.
Being on the right band at the right time is my secret, I only ever work the greyline.
Best wishes my friend.
I made my first dipole without using a balun, however I have a 1:1 current choke at the radio end. Is this the same thing as a bulun? and is the placement of it at the radio, instead of the antenna feedpoint a problem? Thanks
In a perfect world, with a dipole above perfect ground and no buildings nearby etc, you would have equal currents which cancel out in the feeder. This is rarely the case and some current will flow on the outer skin of the coax back down towards your radio. For QRP you don't need anything, however if you plan on running a bit of power then a common mode choke near the radio is a good idea. A 1:1 balun can be used to help match the BALanced dipole legs to the UNbalanced coax feeder. Belt and braces using both really.
Great, Great Video!!! I'm a new ham to HF. been messing around with VHF&UHF for years but not so much HF. Just got a QRP radio Xiegu x6100, It's going on three weeks now trying to configure a HFJ 350m antenna to work with it (No Luck) All I get on every band is harmonic tones and static. I have a 1:9 Balun coming in tomorrow (Saturday) from Amazon. Was wondering if you have any videos connecting a Balun that shows best setup for 1:9 Balan. Meaning counterpoise, configuration amounts of radials & length of redials? The radio is fine (no damage, new) As last week I took it to a park setup only two counterpoises about 18 feet off a 1:1 balun type dipole antenna I put together (have no idea what I'm doing) but a great deal of magic happened on 6m, 10m & 15m. The harmonic tones turned into voices. Could not get out of the US but did achieve under 400-mile contacts. As a new HF operator, just looking for hands on specs showing setup of balun, placement of balun, & wire length of counterpoise, along with amount of counterpoise cables in a pattern that would do better than 400 miles. Thanks again for above video!!! Any help would be appreciated. 73 for now. (My radio does have antenna tuner & SWR adjustment meter on it)
Brilliant! Well done for getting out there and experimenting, really well done. That's what it is all about.
You have lots of stuff going right:
1. Using a random wire with a tuner.
2. 1:9 to help tuner get a match.
So, in the video you'll see I list random wire lengths. All of these will work with a 17' counterpoise laid under the antenna radiating wire, or even out to the side if you can't manage.
Arrange your radiating wire as an inverted V over a branch or mast, even 5 metres or yards for the apex will do. It will also work as a sloper.
Now the radiation pattern will vary by band, and it won't be as good as a resonant antenna cut for a band, however when the bands are open, you will get some nice surprises, especially on the higher bands through the day.
I use 41'and 17'. I also use 84' and 17', which is a W3EDP. You can go as low as 25' or 19' but you'll not get 40 m with that length.
As for videos, you see me work a pile up in my Ulva Island videos from last November. I go over the mast arrangement and you can see the antenna goes to the Un-Un and straight into the radio. With QRP there isn't the need for a choke.
As for your question about more radials. Well I wouldn't bother for a random. They may help with a tuned antenna however radials on the ground behave very differently on rocks, wet grass, dry earth etc. If you want a resonant antenna with radials, then a vertical with elevated radials works best. See my video about a simple dx 20 m wire.
Hope this helps! Ask away if you need more help.
73, Fraser MM0EFI
Always appreciate your videos Fraser! Keep up the excellent work! 73! Tim, DK8MT
Tim, Thank you for your support. I'm glad you enjoyed it.
73, Fraser MM0EFI
Thanks Fraser. I've recently started to do activations. I've been subscribed for some time but couldn't find a video where you show the full antenna setup procedure for a linked dipole on a summit. Would you consider including the full pole/antenna erection in an upcoming summit video? There's lots of advice from other channels on how to do it on a perfectly flat, open, grassy space but very little on a rocky summit with limited space and an abundance of wind. I'd love to learn from your experience. Phill - VK7ID
Hi Phil, Good to hear you're getting out. It will soon be VK to GM summit to summit season! So, we'll need to get up in a hill for that.
Here's a video I did a while back, but I will do another one in the next month or so.
ruclips.net/video/vS5zwNagKUI/видео.html
@@theradiorover "A wee swally", love the accent! Thanks so much, very much appreciated. I've progressed from a 9m fishing squid pole and a 4 band HyEndFed portable EFHW to a SotaBeams 6m pole and 20/40 linked dipole saving lots of weight, making setup much easier, and eliminating RF feedback into the radio/mic. I see you use the "layout the dipole then come back one metre" method. I'll be sure to give that a crack!
@@pgroom I've got a new dipole to test. Watch this space!
Thank you for the video. Just a quick question. If I run a QRP rig (let's say up to 10 watts); I don't need any of these, right?
Fred, No that is not correct. They all do different things.
The 49:1 is for an EFHW and is very necessary. Consider it part of the antenna. The radio should not need a tuner.
The 9:1 is for a random. You need a radio with a tuner or an external tuner. The tuner may get a match on the random without the 9:1, so this one may not be necessary.
The balun for the centre of the dipole is not necessary for QRP.
The choke isn't necessary for QRP but is advisable as it will help keep RF out of your radio, mic. cable, and mic. which could affect your tx audio.
Hope this helps, Fraser MM0EFI
Thank for that Fraser. I just started using a KX2 for SOTA and unbalanced aerials. Given that the Kx2 will tune almost anything do you use an unun or choke with yours? Dave Ei3ixb
Dave, for QRP I don't always use a choke., mainly when I forget with my EFHW, or when the antenna is connected directly to the radio or the 9:1, 49:1 is straight to the radio.
My recent balun video describes this. Also check out the bicycle portable one, where I plugged the EFHW straight into the kx2 because I forgot the coax.
73, Fraser MM0EFI
So for a common mode choke, what would be the preferred ferrite mix, number of turns, and type of wire (coax or 2 strands of teflon wire) for maximum attenuation at 27 mhz?
I have a Solarcon 99 that seems to be radiating from the feedline even with an "ugly" balun at the feed point. Everything is sufficiently grounded.
Air core should work fine at 28 MHz. Have a look at this... www.karinya.net/g3txq/chokes/
The definitive work on chokes. The table has been replicated many times.
73, Fraser MM0EFI
Thank you !!
Very Useful information, and I confess to making all these mistakes. 73. :)
Yes, we all have! Once you work it out, it's not too difficult to remember which one to use where.
Cheers, Fraser MM0EFI
Why only endfed, random wire, and dipole antennas. Why not verticle and yagi antennas also? I am a bit confused about that as most videos address EFHW antennas when talking about UNUNs and chokes.
Hi George, The same rules apply.
Eg: if a vertical is an EFHW or random, then use the same type of transformer. A ¼ wave vertical with ground planes doesn't need anything, but it is always a good idea to place a choke in the feed line with any antenna.
A yagi is just a dipole with added reflectors, so the same rules apply.
I hope this helps. The video was not supposed to be too technical, instead it was designed to be an overview of which types of device to use with different types of antennas.
73, Fraser MM0EFI