Thanks for the explanation. I was taught the radiating wires of the dipole "see" each other. In a perfect center fed dipole the wave traveling out along the wire sees a reflection of itself in the other wire and the impedance stays the same, but in an unbalanced situation the wave traveling out from the center conductor sees itself both in the other half of the dipole and in the outer sheath of the coax and now the impedance is not the same because the outer skin of the coax has become part of the dipole. This results in RF flowing along the outside of the coax. The BALUN is there to hide or remove the electrical RF connection between the radiating dipoles and the coax and make the coax 'anonymous'.

Dave, you are a natural teacher. Thank you.

Thankyou. I learned something new today! Great explanation of what a balun is, clear and concise without opinion-mongering or trying to sell anything.

Another great explanation by a wonderful sage. Thank you, sir! My goal when I'm on the air is to work mentors, like you, that have influenced my passion in this hobby. Hope to hear you soon, Dave!

Thank you for this explanation!

Fantastic video Dave. You answered a question I have never found the answer for. Great informational video. Thanks so much.

Dave, I started watching your videos about 6 years ago while I was studying for my technician license. I now have my General and just bought my first HF rig today! Here I am again years later, doing research while trying to build my first dipole. The information is as solid as ever and easy to follow. Thanks for these videos, Dave! They have been an invaluable resource as I learn more about the hobby.

Finally, after days or month of searching i found a very good and quick explanation of Balun. The other videos from other people talk a lot. Now i have understood what balance antenna and unbalance cable mean. Thanks you man for this video.

Thank you for this excellent explanation!

Very good information. Thanks for sharing all your wisdom!!

Nice Video Presentation! I was not educated in this particular topic, BUT now I am after watching this video. I think I got 95% per cent of what was said reasonably understood. I think if I REPLAY this video along with some practical hands on experience, I will have all concepts and theories down pat. THANK YOU! This was Very Helpfull to me because I will soon be putting up a 20 Meter Di-Pole Antenna, and I want to do it right the FIRST TIME!

Thanks, David great explanation.

I love your videos Dave. I first discovered your channel when I was studying for my exams. 2 years later as a General license holder, I still find myself coming to your channel for advice. Thanks Dave. 73 de KQ4AYG

well done Dave, thanks!

Really informative, thanks Dave (:

This is the first time someone has explained this topic in a way that I halfway understand. And I have searched for a LOT of explanations here on KZread for baluns.

Thanks for this.

Great video, Dave. I wish my EE profs would have explained it that well.

Good discussion, long time away from ham, retired now and need lots refresh of stuff i have forgot over the years thank you for sharing.

love your content. you explain things really well. have you done a video on how toroidal ttransfoerms work and how you wind them?

Thankyou,now I understand !! Xxx

Good question. Great 👍 answers.

excellent!

Thanks!

That was very helpful Dave given I will soon be purchasing an 80M antenna.

Great video! Do you have any videos explaining what a balun would do in comparison to a unun ? and the difference between them? Again, great explanation on above video, well done Dave, Thanks!!!

As always, Dave can explain complex ideas for all to understand. This is totally off topic, but to all hams please take some time away from the shack for fresh air and exercise! God bless and 73!

One point that is rarely raised is the fact that a straight section of feedline forms a Balun due to it's inductance per unit length.

We try to stop RF from coming back to the shack with no luck with everything you said in this video !

@tedmead465

4 ай бұрын

You need to consider all paths it can take, not just feedline. These can include any plumbing, grounding and power conductors, and any metal objects. These all can induce noised from stray rf. Bonding metal objects has to be carefully planned as to prevent the occurance of a ground loop. You cant always stop rf from enntering the shack , but minimize it as much as you are able.

That pretty good. I am in Boston NY and with center fed dipole no balun found a 3rd reason to use 1:1 balun transformer. it's rain and snow. causing static build up on antenna making lot of noise or a voltage Hazard to radio. the balun makes a DC path to ground discharging static build up . also nearby lightning strike makes a EMP that can make a voltage spike that can damage radio.DC ground does a lot to help with this. I had the noise so bad when snowing my recieve was well over S9 on radio. just the 1:1 alone dropped noise to S3 or less. 73's

Dave, do I need to install a Balun if I’m making a simple dipole antenna (using wire only) to only receive FM radio stations? Thanks Dave. Very educational video!

I spent the last few weeks trying to decide what wire antenna to put up. Found the old box of radio stuff and used the "Remote Balun - 4:1", used on of the Zepp that is a dipole of 132' long, climbed the two towers which are about 160-70 feet apart and attached new rope and pulleys. The height is about 40 feet up at a wnw and sse compass reading. hadn't been on the air in many years, made a contact on the Rag Chewers net. No tuner and SWR almost 1:1.2. I'll be 73 on Dec. tenth, Thanks and 73's. n5qdm

I still don't have a complete understanding of what a balun does or if I need one. I need it explained in three sentences or less. I'm familiar with forward and reflective power of a transmitter and antenna. Thank you for sharing this video and your knowledge. I will watch again.

I understand that circuit balancing can get noise to cancel in a load of done properly. How would you balance a source/load if one were trying to balance a circuit for common mode rejection in the load/differential amp? I imagine a balun would be used to get a twisted pair or shielded twisted pair to an amp but how is the unbalanced signal source balanced? How does this look?

Yes, when I get thrown in the pokey, I need a balun.

i bet half my qso are made from my coax, the other half from the antenna.. balun just turns power to heat rather than on the air

OK, so if I'm doing an off-center-fed dipole I should (presumably) use a balun or an unun, but which, or does it matter?

I have a halfwave end fed vertical for 27MHz., on the analyzer, the SWR is no more than 1.3 through the band. Problem is, when I use a linear amp at low power around a hundred watts, SWR is below 1.5, but on high of around 150 watrs, the SWR is only reseonant 10 channels in middle of the band and it's 2:1 on lower and upper channels. What could be the problem and the solution?

Baluns =balanced antenna, UnUn = Unbalanced antenna! Simple enough.

Could I use a 1:1 inline current balun and ferrite beads?

@davecasler

3 ай бұрын

It's redundant but won't hurt anything. I'd suggest using one or the other.

For the outside RF can't you use a radial to remove that reflected RF? Or would this rob you of power to form the radiation pattern. I guess the ferrite choke would be cheaper but would it make your antennas hotter? Not an electrical engineer, sorry if the Q is in the left field...

Why does the RF take two different routes in the shield? Skin effect has always referred the outer most diameter, yet you're saying that "departing" RF is conducted on the inside of the "skin"?

@sfrahm1

2 жыл бұрын

Yep, RF energy travels along the surface of the conductor or waveguide. The differential mode RF energy from the radio travels along the outside of the inner conductor and along the inside of the outer conductor and within the dielectric space in between the two. Common mode RF energy travels along the outside of the outer conductor and is measurable with an RF current meter like an MFJ-854 or with my own RF current meter that I have constructed.

@peterfardell9267

Жыл бұрын

You say voltage" early on but this is really "current". The balun is designed to prevent "common mode" current. The secondary purpose is to match an impedance , eg 300 ohms to 50 ohms.

@peterfardell9267

Жыл бұрын

Baluns are preferred. The main problem is that many baluns even commercial ones are not constructed correctly.

I always use choke baluns

I've noticed many professional VHF and UHF folded dipole arrays have no RF chokes on the feed harness. They do use coax impedance transformers, but no balun and no choke. Why?

@CARLiCON

2 жыл бұрын

isn't that for impedance matching? the antenna itself is close to 300 ohms, just like flat wire. However, coaxial cable has an impedance of 75

@robbehr8806

2 жыл бұрын

@@CARLiCON Yes, that's my point -- the antenna has proper impdance matching, but nothing to stop RF from traveling along the phasing harness and other feedline.

@sfrahm1

2 жыл бұрын

@@robbehr8806 The 75 ohm to 300 ohm impedance transformer also converts the feed from unbalanced to balanced. So much of the potential for common mode current is avoided that way instead.

@darkdanthe

Жыл бұрын

@@CARLiCON Coaxial cable has 50 ohm impedance.

You're a good teacher my friend, God bless, be well. from sTePhEn - FOO WAS HERE

Is it possible to have too much coax coiled up to act as an ugly balon? I have about 25 feet of Messi and Paploni UltraFlex 7 coiled up just below the antenna on my 10 meter dipole. KQ4OFQ, 73s.

I live in Hawaii and now that we don't have a radio shack (R.I.P.) i don't have access to a lot of components. I've been tearing apart every bit of recyclable gear I can get my hands on and I can't find a single ferrite bead other than the ones that are already epoxied together and far too small (ie inductors) with the way tech works these days and the fact that I can't get my hands on components that used to be readily available, bugs the Hell out of me. Can I make an air core balun? I have a couple of radios that are analog but I don't want to sacrifice anything in the name of the next foxhunt in a couple of weeks. I want to thank you for bringing your knowledge to the table because we're a dieing breed. If you have any advice I'd love to see a video covering a diy balun that doesn't require an Amazon shipment (or ferrite) that'll take far too long. I miss the analog days when we could do everything without blowing out a crappy radios front end. At the very least I only need to receive and I've seen some ideas. I'll never transmit on some of the crap ideas I've found, but I know to at least ask someone who's been at this longer than I have for advice before i start blowing out components. Thank you for your time and the content. When I am no longer poor I'll gladly donate and perhaps buy you a beer or whatnot someday. 😅🤙🏽

If you choke the return RF, where does the energy go? Is it dissipated as heat in the choking component?

@sfrahm1

2 жыл бұрын

Yes. If the RF impedance of the balun is NOT high enough, together with too much common mode current, the energy can cause overheating of the choke core and windings. If the RF impedance of the balun IS sufficient, as designed for the applied power level and common mode voltage issues at hand, the current flow and hence dissipated power are limited to a very low level. The correct use of a transmission line type transformer as a balun will typically have very low loss. Please beware, there are many poor examples of balun and unun design and use to be found here on the interwebs and in the market.

@g-whiz286

2 жыл бұрын

@@sfrahm1 - I wasn't talking about using a BALUN. I was referring to Dave's suggestion of placing the coax through a series of ferrite cores. No BALUN.

@sfrahm1

2 жыл бұрын

@@g-whiz286 That is one way how you can make a 1:1 balun, by using a string of ferrite cores. That gets very expensive with the number of cores required using that method to do much good at all and can only handle very limited power. The best way is to use multiple turns of something like RG-405 or RG 402 on a larger core or stack of cores. I have an RF current meter to measure the common mode current coming back on the outside of the coax & have recently tried building prototype baluns 1/2 a dozen ways including the string of single turn cores and have actually measured them all.

@BusDriverRFI

2 жыл бұрын

Sfrahm it makes no sense to say the return rf is dissipated as heat and it is efficient. Either it dissipates as heat and is inefficient or it doesn't dissipate as heat and is efficient. My hobby isn't to generate heat first.

@sfrahm1

2 жыл бұрын

@@BusDriverRFI Efficiency is directly related to just how much power is dissipated as heat. If a Balun is operating with 99% efficiency, 1% is dissipated as heat. If the Balun is 99.9% efficient, 0.1% is dissipated as heat. Most baluns on the market are worse than either of these examples. With 99% efficiency & 100 watts coming out the radio & 99 watts going to the antenna, 1 watt of heat worst case is fine. 99.9% efficient, 1500 watts out of the box, 1498.5 watts to the antenna & 1.5 watts of waste heat worst case is also just fine.

Like it I'm just wondering if the same principle could be applied 11 M BAND a 49 to 1 Transformer on the 11 band I heard is better however when I was looking at the coil you were doing 9 in candy Spears is well on the 11 band or does the coil have to be smaller you're talkin about the 80 M BAND can I use the same principle I know it's an odd question I do believe in pushing the limits of my equipment getting a bit more range doing dxing as a 200m wattage can turbo 1000 km on a single Crystal that will roughly emanate less than a quarter of a wattage signal well Chapo 1000km I know it's a long shot question however I rather ask get a partial answer than not having an answer thank you for the videos and 73

What are you referring to? The term balun is now used by everybody for everything.

@mightymulatto3000

2 ай бұрын

You are correct. Marketing terms are out of hand. It seems ground loop isolators/isolation transformers are being called baluns as well as neutralizing transformers. It also seems that media converters like BNC to twisted pair are also being called baluns. That said I'm still trying to figure out the best approach of dealing with pickup voltage as well as voltage caused due to differing ground potentials.

💯👍👍👍🙋‍♂️🙏

I have not used a balun. I did a lot of work mostly 80 meters with an old tube rig. Watched the SWR and kept the antenna tuned to frequency. N0QFT

@BusDriverRFI

2 жыл бұрын

1:1 baluns do nothing. It's a joke on the ham community.

In most cases, no. The difference will be very slight, insignificant.

If the SWR is 1:1 there will be no RF on the outside conductor without a balun. But, that limits your operating bandwidth and in the day, few even had an SWR meter and below a 100 watts, not often an issue. Baluns do have some loss but, they do provide a DC to broadcast band, or so short reducing static buildup and overload.

Hi Dave A typical 1:1 current Balun is NOT wired at all like what you drew. What you showed in your drawing was similar to how an audio or power transformer is usually wired. I refer you to the works of Jerry Sevick, W2FMI especially his book Understanding, Building, and Using Baluns and Ununs

@RESISTAGE

2 жыл бұрын

I noticed that too.

@BusDriverRFI

2 жыл бұрын

A 1:1 current balun can be wired in several ways with almost identical results. There are going to be some bandwidth limitations to some configurations as compared to others. But the key takeaway is that baluns are transmission line transformers. There are many types of transformers. Since our formula R +/-jX is a two port series designation, we aren't really worried about balanced and unbalanced. It's all the same.

@wilfredswinkels

Жыл бұрын

indeed. Also an open dipole is 73Ohm's instead of 50. That's why you have an SWR of 1.5 on the higher bands and 1:1 on 80 and 40, because for those bands the antenna is virtually lying on the ground. And Just don't use a balun..... yeah, more wire for you to radiate.....outside of the coax....your microphone lets your lips tingle....meh

im working 5 THOUSAND MILES on DEAD BANDS with dipoles, vertical and ONE TO TEN WATTS. And doing it regularly. My antennas dont need toy baluns. Baluns are NOT FOR ANTENNAS. .They are for coupling Transmission lines together Stop playing popularity and Maker games and learn to make and tube a proper dipole.

@g0fvt

2 жыл бұрын

A "proper" dipole? If you mean the usual half wave centre fed it is clearly a balanced antenna (limited by the environment). Obviously they will function with or without a balun of any sort. But you seem to have missed the point entirely.. An effective common mode choke type balun at the feedpoint of a dipole can do wonders for RFI issues both transmit and receive.

Less than a 100 watts, I don't see the need for a Balun.

@BusDriverRFI

2 жыл бұрын

Baluns (or transmission line transformers) are indeed necessary to correct for impedance mismatches. 1:1 does nothing.

@sfrahm1

2 жыл бұрын

A balun can reduce common mode receive noise from shack computer equipment and such like from getting back into the antenna. I've actually got baluns on both ends of the coax, at the radio and the antenna end, on the last antenna I was last testing just this week.

@BusDriverRFI

2 жыл бұрын

@@sfrahm1 So you're saying it readjusts the phases of the different sine waves coming up the transmission line and it knows how much to adjust the common mode out depending on how much phase is needed to be adjusted? Interesting. How does it know how to adjust the phases properly?

@sfrahm1

2 жыл бұрын

@@BusDriverRFI No, I didn't say anything like that at all. If you have a differential mode impedance on the inside of the coax of approximately 50 Ohms feeding a 50 ohm antenna and a common mode impedance as measured on the outside of the coax of approximately 4K ohms it becomes very difficult for any common mode noise current to flow. If you have a piece of solid wire conducting electrical noise from inside the shack back out to the antenna you can often hear much more receive noise. It's kinda hard to get very much current into a 50 ohm load through a 4,000 ohm resistor isn't it? Phase becomes relatively unimportant very quickly in that case.

@BusDriverRFI

2 жыл бұрын

@@sfrahm1 on my coaxial cable, the inside of the coax is actually shorted to the outside of the cable. So on mine, fortunately, the inside and the outside are 50 ohms with respect to the other conductor.

the video has no mathematical explanation or electronic formula

@willthomas7490

6 ай бұрын

No. No it doesn’t. You got an issue with that?

Coax cable is a -two-- conductor cable, not a single conductor. This post is not accurate. For a/c to flow there always have to be two conductors. RF is a/c. The shield of coax cable is the other conductor, like it or not. You goofed Dave.

@paullalli7774

2 жыл бұрын

No idea why 'two' is crossed out.

@BusDriverRFI

2 жыл бұрын

Many do not understand the term "common mode current" and they make up crap. They say that there are currents flowing on the inside of the shield going one way and currents on the outside going the other way on the same shield. It's false. Now there are reflected signals but they occupy the same part of the same shield but unless you have a triaxial cable, you don't have electrons educated enough to know what part of the shield to remain.

@g0fvt

2 жыл бұрын

@@BusDriverRFI with respect you can do a skin effect demonstration with just a small piece of unetched PCB.

@BusDriverRFI

Жыл бұрын

@@g0fvt skin effect is an effect for the outside of the conductor. Not on the inside.

@g0fvt

Жыл бұрын

@@BusDriverRFI it is on the surface

What the heck does R+/-jX mean, Dave? It means R + an Xc + an XL where hopefully the X's cancel. It means these 3 comps are in series. What do we know about a series ckt? Current is equal across the series. This garbage you are saying contradicts physics. You all do this.

baluns are a direct short on your radio. never use them. always tune your antenna or use ATU.

I'm a CBer, and there are few inaccuracies and factual problems with this video. I'm very surprised, for one, that fellow hams need help with the very basics of this topic and theory. Second, I'm shocked that more hams are not picking up on errors in this vid. My advice to anyone publishing videos on RF theory, be sure you know what you're talking about. If you're unsure, don't pretend and publish anyway. Lastly, sir, I suggest you go back to the text book and study closely this time. You may wish to look at transmission lines, common mode current and a refresher on your dipole theory while you're at it. Some would argue that it should not take for a CBer to be educating hams, but that's just a prejudice that doesn't make any sense, as someone operating on the Citizen's Band could have any education or intellect. You could be Albert Einstein or Nikola Tesla for all I care, it is irrelevant. It would seem that many hams are in question though, because they have a license based on the fact that they've supposedly studied and understood this simple 101 theory, which would suggest they're a phoney.

@davecasler

Жыл бұрын

I stand behind the video.

@arconeagain

Жыл бұрын

@@davecasler yeah I've noticed that hams can't admit when they're wrong. They ridicule CBers at the drop of a hat too. Well you keep getting those pats on the back from people that wouldn't know any better, that way you can perpetuate this nonsense. What's stupid is that all they have to do is pick up a book and learn independently. Too lazy I suppose, these days people want answers yesterday and they want it now. Too reliant on other people to do their homework for them, like me. I've done it the honest way, decades of study and practical, and a formal education.

Thanks Dave, very well explained, in a way I understood. Jim KB8PET

Thank you, Dave. N0QFT

Thanks!