I appreciate that you draw the proper schematic for an auto-transformer. It’s so much easier to understand than a sketch of a torpid with colored windings.
Thank you Dave, a very good learning experience which answered a number of questions for me - cleared the fog!! 👍😀 I shall apply the lesson to my construction efforts. Regards - Phil, Suffolk U.K.🇬🇧
Since you said that the off-center dipole has a nominal impedance of 400 ohms, why do you use a 4:1 balun? Shouldn't it be an 8:1 balun? (since 400/50 = 8)
Well you certainly *could* use an 8:1, if your installation is at the ideal height above ground, no slope, etc., all things in a theoretically perfect world… and if you can find one, or plans to make one. But in practice, many typical compromises made/forced in the installation tend to be things that lower the impedance some anyway. And a 4:1 balun is very simple/cheap to make, readily available for purchase, etc. Therefore, chances are pretty good that 4:1 is going to get you close enough to beautifully matched such that the SWR is reasonably low, & hence the losses reasonably insignificant.
I've modeled these OCF's and they are indeed ~200ohms on their respective resonant bands. They are not 400 ohms. So you do need a 4:1 to put it into the ballpark. I've not gone back to see what he said but if he said 400 ohms, he misspoke.
@@BusDriverRFI It also depends “how far off center”. There’s a spot somewhere along a dipole where it IS 400. If one is home-brewing an OCF, one might pick a different distance from center based on what balun one has handy.
Thank you. I have not used baluns much. On 80M, it seems that reception is better without the balun, than with one for a center fed dipole. That was for my home antenna and one used for field day. I was using an old Galaxy 5 vacuum tube/transistor hybrid transceiver at home and a friend's solid state rig during field day. That does not make sense to me, but that is what I experienced. Others used the same baluns and had some improvement. I wished I would have taken detailed notes, but I did not. N0QFT
Dave I've been watching your videos for the last year or two and have learned a lot, thank you. I do have a question that is kinda off topic for this video, but the name of your channel is, " Ask Dave" so I'm asking, do you have any knowledge of the Galaxy dx 66 v radios? I have one that's in really good shape but has been converted to CB . But, now I will soon be getting my technician amateur license and want to convert it back to 10 meter band. I do have the owners manual but it's kinda lacking except for general set up and operation. Can you tell me what I need to do to accomplish this. And anything else about the radio on 10 meters. It works great on CB but now it's time to move on up, any help is appreciated. God bless.
It's actually a chunk of change out of your wallet. It gains you nothing. 1 goes in and 1 comes out minus small losses. I get the impression some hams like this don't want to stir the pot and dis 1:1's because there are so many businesses who sell them and so many hams have bought them. I bought one (ferrite used at 10.115MHz) and tested the output to the dipole. Essentially no difference in antenna current. Only a small amount of loss over using a direct connect. So they are a good deal if you just need a little bit of loss.
@@BusDriverRFI but nobody says it would add any gain, the idea is that it disconnects galvanic connection between antenna and transceiver eliminating problems of common current and the likes. Also it seems like Dave was not talking about wasting money, more like having some problems with this setup.
Thank you. I am about to attempt a repair on my old Windom (Off center dipole) and I've been wondering / struggling with exactly what the balun is at the off-center feed point. You just answered that and gave me a better idea of what I need to do. /73
There can be a completely long white paper written on this subject. How well it will act as a counterpoise will depend upon many factors such as frequency utilized, possible telescoping electrical connections, how well it's coupled at the feedpoint, length of the antenna pole and whether it's grounded at the base. If we are looking at it holding up a horizontal antenna for example and it's not even connected to the braid, it shouldn't have hardly any affect.
Hi Dave, Thank you for being congnizant regarding color blindness..... I am. And indeed green in low light conditions (for me) is a tuff color to discern. 73s Amigo Art W1SWL
Never Anywhere. I dont need them. I dont need gimmicks. I worked Italy this am on ONE WATT. Dipole. No Baluns. People SELLING baluns need you to need them.
If you have a perfect dipole and everything works and you're a lucky person, then you don't need a balun. But if any of these things aren't true, you'll have common mode currents on the coax shield and you'll need a balun to cancel them. I don't know where Perfect is, but it sure isn't where I live.
Good antenna stuff! Human eyes in general have difficulty focusing blue light as it heads toward violet. It’s just tough to do. There’s a local optometrist whose sign is in that non-focusing blue. I’m sure they drum up a lot of business as folks drive by and can’t see that sign quite clearly…
Smiling! Red, Green, Brown color blind here, skipped my son but got my grandson. Resistor of old, that used the very dark red, green, brown was very hard for me to see, and I would have to call my son or wife in for help.
I used two dipoles cut to 56 feet. Each was perpendicular to the other for good angular coverage. I generally operate CW and was planning to use this antenna on 40, 20, 15 and 10 meters. This is a short dipole on 40 meters and longer on the other bands. I used balanced line to the antennas (about 66 feet long) and connected that to a 4:1 balun. From the balun I used 50 ohm coax to a tuner. Once tuned on a given band I could switch back and forth between the two dipoles without having to retune anything. Nice! These antennas worked great on FD a few years ago. I've always wondered how to determine the impedance at the balun to get to what the SWR was on the coax for each band. Maybe I don't need to bother with all that. :) Thanks...
Excellent Video! I will most certainly be playing this several more times. This is such an important topic " ANTENNA's " and " BALUN's " . The THEORY was well explained here in this video. I think the THEORY becomes more clear with some HANDS ON PRACTICAL EXPERIENCE working with Antenna's and all that is associated with this topic.
Fantastic video demonstration again Dave many thanks. How about Voltage & Current baluns? Would a Doublet perform better with a certain one & does the efficiency increase with a larger capacity design I, e, a 3Kw? I always enjoy your inspiration and educational mentoring Dave. Best 73 GM0KET
the turns ratio is properly figured at the ratio of the secondary to the primary. A 49: 1 unun will have a primary of 2 turns, making the total winding of 14 turns, tapped at 2 turns from one end (for the coax feedpoint). - AL7W
Hi Dave, thanks for this great video! It really helps me understand the guts of what I've already bought, and specifically how dipoles work...all in a concise format. That's hard to do!
Thanks for providing good information. I have one question. Would it be ok to use awg 17 one core copper wire with the torroid, 1:1 current balun? Or isn't critical what wire size to use given a QRP transceiver, maximum 10W output.
The wire size is important for maintaining the proper impedance match through the transformer. If the impedance doesn't match, then you'll have a higher SWR when you put the balun in circuit.
Not to be rude, but that’s a lot I don’t quite understand or honestly really care to know. I just look up the antenna and build it. Usually they end up pretty darn close and I adjust from there. For me just building them is fun and I learn a little bit more each time.
Isn't a dipole fed directly with coax (no balun), a quarter wave antenna with a quarter wave counterpoise? In which case it's a quarter wave horizontal!
If you look at the schematic of an antenna from the perspective of the equation R +/-jx, we know that there is a resistor, inductor and capacitor in series. We know that current in a series circuit is equal. What's on one end is equal and opposite polarity on the other end because they work against each other. Ideally, the Xc and XL are equal and cancel (resonance). The configuration of the dipole centerfed can certainly be looked at as a quarterwave with a quarterwave counterpoise horizontally. But it's virtually the same if you feed it with or without a current balun 1:1. Keep looking at things unconventionally.
Hi Dave - I have a HyEndFed 80-10 with a 49:1 at the end point and as recommended by the manufacturer I placed a 1:1 balun 0.05 lambda away from the antenna’s 49:1 balun. I’m not sure exactly why but it works wonderfully… 145 countries in the past 2 years. Coax acts as the counterpoise into the station. As an aside…at approx. 13 minutes you correctly show a 49:1 balun for an end fed antenna and at approx. 20 minutes you show it incorrectly at 7 turns to 2 turns. Mistakes happen (especially at our age - I’m 73) but it might be exceptionally confusing to a new ham to get conflicting information. Just saying you might want to check your videos before publishing them. Cheers W2RSB | F4WCM.
I like how you state that it works but you don't know why. It really doesn't help anyone to at least guess. With my testing at 30M, I see no difference in performance.
![[TH] FS vs BME - VCT Ascension Pacific - Lower Bracket Final](http://i.ytimg.com/vi/wnygqsR2Fig/mqdefault.jpg)
I appreciate that you draw the proper schematic for an auto-transformer. It’s so much easier to understand than a sketch of a torpid with colored windings.
Thank you Dave, a very good learning experience which answered a number of questions for me - cleared the fog!! 👍😀 I shall apply the lesson to my construction efforts. Regards - Phil, Suffolk U.K.🇬🇧
Since you said that the off-center dipole has a nominal impedance of 400 ohms, why do you use a 4:1 balun? Shouldn't it be an 8:1 balun? (since 400/50 = 8)
Well you certainly *could* use an 8:1, if your installation is at the ideal height above ground, no slope, etc., all things in a theoretically perfect world… and if you can find one, or plans to make one.
But in practice, many typical compromises made/forced in the installation tend to be things that lower the impedance some anyway. And a 4:1 balun is very simple/cheap to make, readily available for purchase, etc. Therefore, chances are pretty good that 4:1 is going to get you close enough to beautifully matched such that the SWR is reasonably low, & hence the losses reasonably insignificant.
I've modeled these OCF's and they are indeed ~200ohms on their respective resonant bands. They are not 400 ohms. So you do need a 4:1 to put it into the ballpark. I've not gone back to see what he said but if he said 400 ohms, he misspoke.
@@BusDriverRFI It also depends “how far off center”. There’s a spot somewhere along a dipole where it IS 400.
If one is home-brewing an OCF, one might pick a different distance from center based on what balun one has handy.
@@kelvin0mql yes. Of course. You can do whatever feels good.
@@BusDriverRFI True.
Not *necessarily* related, but quite true.
LOL
Thank you. I have not used baluns much.
On 80M, it seems that reception is better without the balun, than with one for a center fed dipole. That was for my home antenna and one used for field day. I was using an old Galaxy 5 vacuum tube/transistor hybrid transceiver at home and a friend's solid state rig during field day.
That does not make sense to me, but that is what I experienced. Others used the same baluns and had some improvement. I wished I would have taken detailed notes, but I did not. N0QFT
Dave I've been watching your videos for the last year or two and have learned a lot, thank you. I do have a question that is kinda off topic for this video, but the name of your channel is, " Ask Dave" so I'm asking, do you have any knowledge of the Galaxy dx 66 v radios? I have one that's in really good shape but has been converted to CB . But, now I will soon be getting my technician amateur license and want to convert it back to 10 meter band. I do have the owners manual but it's kinda lacking except for general set up and operation. Can you tell me what I need to do to accomplish this. And anything else about the radio on 10 meters. It works great on CB but now it's time to move on up, any help is appreciated. God bless.
And current or voltage baluns
Life was easier when a box of crayons only had eight crayons.
What does it mean that you have not have good luck with 1:1 balun on simple dipole? What were the problems you had?
It's actually a chunk of change out of your wallet. It gains you nothing. 1 goes in and 1 comes out minus small losses. I get the impression some hams like this don't want to stir the pot and dis 1:1's because there are so many businesses who sell them and so many hams have bought them. I bought one (ferrite used at 10.115MHz) and tested the output to the dipole. Essentially no difference in antenna current. Only a small amount of loss over using a direct connect. So they are a good deal if you just need a little bit of loss.
@@BusDriverRFI but nobody says it would add any gain, the idea is that it disconnects galvanic connection between antenna and transceiver eliminating problems of common current and the likes.
Also it seems like Dave was not talking about wasting money, more like having some problems with this setup.
Thank you. I am about to attempt a repair on my old Windom (Off center dipole) and I've been wondering / struggling with exactly what the balun is at the off-center feed point. You just answered that and gave me a better idea of what I need to do. /73
will a steel antenna pole act as a counterpoise instead of a hanging wire??? K3RJW,,, Ron W
Yes!
@@mikedickson1668 I thought so, but no one ever talks about this, just a wire or wires all the time. Thank you Mike.
There can be a completely long white paper written on this subject. How well it will act as a counterpoise will depend upon many factors such as frequency utilized, possible telescoping electrical connections, how well it's coupled at the feedpoint, length of the antenna pole and whether it's grounded at the base. If we are looking at it holding up a horizontal antenna for example and it's not even connected to the braid, it shouldn't have hardly any affect.
Hi Dave, Thank you for being congnizant regarding color blindness..... I am. And indeed green in low light conditions (for me) is a tuff color to discern. 73s Amigo Art W1SWL
Never
Anywhere.
I dont need them. I dont need gimmicks.
I worked Italy this am on ONE WATT.
Dipole. No Baluns.
People SELLING baluns need you to need them.
Anyone who tells you any differently is just trying to sell you a placebo. I have done the testing on them and agree.
If you have a perfect dipole and everything works and you're a lucky person, then you don't need a balun. But if any of these things aren't true, you'll have common mode currents on the coax shield and you'll need a balun to cancel them. I don't know where Perfect is, but it sure isn't where I live.
@@BusDriverRFI Yeah, who needs engineers and physicists. What do they know? You know better than they do, right?
@@stargazer7644 Are you an engineer or a physicist? Have you had university level classes in these areas?
Good antenna stuff! Human eyes in general have difficulty focusing blue light as it heads toward violet. It’s just tough to do. There’s a local optometrist whose sign is in that non-focusing blue. I’m sure they drum up a lot of business as folks drive by and can’t see that sign quite clearly…
Nice explanation. Thanks!
Excellent video. Thank you
Smiling!
Red, Green, Brown color blind here, skipped my son but got my grandson. Resistor of old, that used the very dark red, green, brown was very hard for me to see, and I would have to call my son or wife in for help.
I used two dipoles cut to 56 feet. Each was perpendicular to the other for good angular coverage. I generally operate CW and was planning to use this antenna on 40, 20, 15 and 10 meters. This is a short dipole on 40 meters and longer on the other bands. I used balanced line to the antennas (about 66 feet long) and connected that to a 4:1 balun. From the balun I used 50 ohm coax to a tuner. Once tuned on a given band I could switch back and forth between the two dipoles without having to retune anything. Nice! These antennas worked great on FD a few years ago. I've always wondered how to determine the impedance at the balun to get to what the SWR was on the coax for each band. Maybe I don't need to bother with all that. :) Thanks...
I am red green color blind
Excellent Video! I will most certainly be playing this several more times. This is such an important topic " ANTENNA's " and " BALUN's " . The THEORY was well explained here in this video. I think the THEORY becomes more clear with some HANDS ON PRACTICAL EXPERIENCE working with Antenna's and all that is associated with this topic.
Fantastic video demonstration again Dave many thanks.
How about Voltage & Current baluns? Would a Doublet perform better with a certain one & does the efficiency increase with a larger capacity design I, e, a 3Kw?
I always enjoy your inspiration and educational mentoring Dave.
Best 73 GM0KET
Hi this is Timothy Pullen could you possibly point me to a website where I can do some training to get my ham license do you have any recommendations
the turns ratio is properly figured at the ratio of the secondary to the primary. A 49: 1 unun will have a primary of 2 turns, making the total winding of 14 turns, tapped at 2 turns from one end (for the coax feedpoint). - AL7W
HOLY COW! Now I get it! Thank you so much for this valuable video!
I have red-green color deficient vision. Color blindness comes from your mom.Thanks for explaining the mysteries of baluns.
FYI, Funny, Balun was used in a scifi series to describe people who were brought back from the dead and had to kill every day to stay alive.
A beginner's question: Do you need a balun for a receive only EFHW wire antenna?
Great video Dave! Excellent explanation.
Hi Dave, thanks for this great video! It really helps me understand the guts of what I've already bought, and specifically how dipoles work...all in a concise format. That's hard to do!
Your videos get messy, but they are effective. Thank you good sir.
Thanks for providing good information. I have one question. Would it be ok to use awg 17 one core copper wire with the torroid, 1:1 current balun? Or isn't critical what wire size to use given a QRP transceiver, maximum 10W output.
The wire size is important for maintaining the proper impedance match through the transformer. If the impedance doesn't match, then you'll have a higher SWR when you put the balun in circuit.
Great video and instruction thank you
Not to be rude, but that’s a lot I don’t quite understand or honestly really care to know.
I just look up the antenna and build it. Usually they end up pretty darn close and I adjust from there.
For me just building them is fun and I learn a little bit more each time.
good for you
@@grumpy_ken Oh don’t be a SADHAM, way too much HamSnobbery clouding up the place already.
@@FireRescue884 watches video on subject they have no interest in. Leaves dumb comment. Calls other ppl names. 👍
Great video as always sir!
Always thank You
Smart Bloke.
From my experience I have to agree with No Balun on single band dipoles. Thanks Dave
Isn't a dipole fed directly with coax (no balun), a quarter wave antenna with a quarter wave counterpoise? In which case it's a quarter wave horizontal!
If you look at the schematic of an antenna from the perspective of the equation R +/-jx, we know that there is a resistor, inductor and capacitor in series. We know that current in a series circuit is equal. What's on one end is equal and opposite polarity on the other end because they work against each other. Ideally, the Xc and XL are equal and cancel (resonance). The configuration of the dipole centerfed can certainly be looked at as a quarterwave with a quarterwave counterpoise horizontally. But it's virtually the same if you feed it with or without a current balun 1:1. Keep looking at things unconventionally.
Hi Dave - I have a HyEndFed 80-10 with a 49:1 at the end point and as recommended by the manufacturer I placed a 1:1 balun 0.05 lambda away from the antenna’s 49:1 balun. I’m not sure exactly why but it works wonderfully… 145 countries in the past 2 years. Coax acts as the counterpoise into the station. As an aside…at approx. 13 minutes you correctly show a 49:1 balun for an end fed antenna and at approx. 20 minutes you show it incorrectly at 7 turns to 2 turns. Mistakes happen (especially at our age - I’m 73) but it might be exceptionally confusing to a new ham to get conflicting information. Just saying you might want to check your videos before publishing them. Cheers W2RSB | F4WCM.
I like how you state that it works but you don't know why. It really doesn't help anyone to at least guess. With my testing at 30M, I see no difference in performance.
I love your videos thnks DF1NPZ