Posted: 5/5/2013 11:19:25 AM EDT
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I have a 3 band dipole that I built. Im using the "UGLY BALUN" (no, it isnt technically a balun). My question is, could I use such as this instead?  OK, so maybe not. A 4:1 is used on a dipole but a 1:1 seems to be used on a multi band????? Random thoughts is all |
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Quoted:
I have a 3 band dipole that I built. Im using the "UGLY BALUN" (no, it isnt technically a balun). My question is, could I use such as this instead? http://www.universal-radio.com/catalog/antsup/2286.jpg OK, so maybe not. A 4:1 is used on a dipole but a 1:1 seems to be used on a multi band????? Random thoughts is all I think you use a 4:1 balun when you are matching a folded dipole, for a straight dipole you want 1:1. Read up on antenna impedance and matching. You may have to read it more than once. |
I am not a guru.  But you'd use the 4:1 if you want impedance transformation. Is your antenna just a simple dipole, or does it have traps, coils, etc? Or does it have multiple wire elements on each side? If it's not just a simple dipole and is ~50 ohms on each band then you don't have any need for the 4:1 balun. What you probably want is a current choke.
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No, a dipole, single band or fan ("multi") should use no balun or a 1:1 current balun.
The "Ugly Balun" is a choke balun or current balun. It does the same thing, though not as well on low bands, as a 1:1 current balun. A 1:1 current balun is not a 1:1 transformer, but actually a long ferrite bead. The purpose of this choke or current balun is to keep RF off the shield and in the antenna and not in your shack. The Ugly Balun works well on 40 meters and higher, but it known to not be effective on 80 meters on down. You also need to look at the cost of coax for the length needed (usually about 20'-25') vs. a 1:1 current balun. I had some RF in the shack on 80 meters that went away when I replaced the Ugly Balun some years ago with a choke balun. Dipoles in free space are actually about 75 ohms, but the impedance drops as you approach the earth. At realistic mounting heights they are closer to 50 ohms. If you have a very low dipole, such as NVIS, impedance is lower than 50 ohms. This is where having an actual antenna analyzer rather than just an SWR meter comes in handy. You may be adjusting length when you should be staying at resonance and doing other things to get a match. 4:1 baluns are useful for loops and OCFDs (aka "Windoms"). Those antennas are about 200 ohms, and the 4:1 balun brings that down to around 50 ohms to match the coax and transceiver. In most cases, a current balun is preferable to a voltage balun. |
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Quoted: Yes, its a multi bandI am not a guru. But you'd use the 4:1 if you want impedance transformation. Is your antenna just a simple dipole, or does it have traps, coils, etc? Or does it have multiple wire elements on each side? If it's not just a simple dipole and is ~50 ohms on each band then you don't have any need for the 4:1 balun. What you probably want is a current choke. I have the ugly balun/choke on it. just curious about the reasoning for each I guess. |
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Quoted: Which one did you end up going with?No, a dipole, single band or fan ("multi") should use no balun or a 1:1 current balun. The "Ugly Balun" is a choke balun or current balun. It does the same thing, though not as well on low bands, as a 1:1 current balun. A 1:1 current balun is not a 1:1 transformer, but actually a long ferrite bead. The purpose of this choke or current balun is to keep RF off the shield and in the antenna and not in your shack. The Ugly Balun works well on 40 meters and higher, but it known to not be effective on 80 meters on down. You also need to look at the cost of coax for the length needed (usually about 20'-25') vs. a 1:1 current balun. I had some RF in the shack on 80 meters that went away when I replaced the Ugly Balun some years ago with a choke balun. Dipoles in free space are actually about 75 ohms, but the impedance drops as you approach the earth. At realistic mounting heights they are closer to 50 ohms. If you have a very low dipole, such as NVIS, impedance is lower than 50 ohms. This is where having an actual antenna analyzer rather than just an SWR meter comes in handy. You may be adjusting length when you should be staying at resonance and doing other things to get a match. 4:1 baluns are useful for loops and OCFDs (aka "Windoms"). Those antennas are about 200 ohms, and the 4:1 balun brings that down to around 50 ohms to match the coax and transceiver. In most cases, a current balun is preferable to a voltage balun. |
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This was my main "inspiration" of my antenna http://www.qrz.com/db/AE5JU My creation  |
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Clear Signal www.coaxman.com their #823A.
If you are not running an amp you are probably OK with the setup you have. I didn't have any problem with the Ugly Balun until I started running an amp. I was getting bitten in the shack, tingles and shocks on 80 meters when running over 300 - 350 watts. With the Clear Signal 823A I can run some "fire in the wire" with no problem. BTW, that looks quite well done! |