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making a 1.1 choke balance

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Old 01-21-2009, 11:15 AM
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http://www.firecommunications.com/r2ch21.pdf

contrary to popular belief that only dipoles need baluns, verticals and longwires can require baluns (more correctly called common-mode chokes or isolators in this application) also. This article shows why baluns (or more properly common-mode chokes) might be required, and what the choke can do.

http://www.w8ji.com/verticals_and_baluns.htm

current, not voltage

http://www.firecommunications.com/keepcurr.pdf

Last edited by freecell; 01-21-2009 at 11:51 AM.

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Old 01-21-2009, 03:28 PM
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thank you all for the help i just isolated my antenna from the mast and didnt even mess with the 1.1 choke balan and i beleive my ground plane is working with my antenna now i seem to be getting out better and my recieve is better

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Old 01-24-2009, 05:21 AM
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Some more info.

K1TTT Technical Reference

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Old 01-24-2009, 07:48 AM
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DXer,
That's good to know, but I'm still puzzled about what the thing is called, "1.1 choke balance". Where/how does the '1.1' and the 'balance' thingys come in? The impedance ratio isn't changed, and the thing isn't 'balanced' to start with.
- 'Doc

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Old 01-24-2009, 08:10 AM
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Is the choke effectively the same thing as a coil inductor inline on the ground shield?



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Old 01-24-2009, 10:02 AM
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to tell if you have common mode,just grab the coax or lay your hand flat on top of your radio whilst keying the mic whist checking your swr.. if the needle moves wilst grabbing the coax or laying your hand on and off the radio,you have common mode currents and your coax is acting as an antenna..
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Old 01-24-2009, 04:06 PM
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C2,
Sort of, kind'a. Since winding it into a coil only affects what's on the outside of the feed line, then it's about like putting a coil with a large reactance on only the outside of the cable. that would effectively stop any AC/RF from flowing there. (That 'AC' in reference to RF is sort of redundant since there is no DC RF.)
- 'Doc

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Old 02-02-2009, 10:21 AM
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If a coaxial feed line is working correctly, there is no current flowing on the outside of the shield. All of the current is flowing on the inside of the cable, on the -inside- of that outer shield. Winding that coaxial feed line into a coil will only affect the flow of current on the outside of that cable, there is no change to the current flow inside that cable. That current flowing on the outside is halted (at best), or at least reduced. It is not redirected someplace else, it just stops right there. And since it is stopped 'right there', the best place for that choke is as close to the feed point of the antenna as possible so that there is less cable affected thereby making a smaller secondary radiator out of the cable. In other words, it 'chokes' off that current flowing on the outside of the feed line. The name 'choke' certainly makes sense in that case, doesn't it? There is no change in impedances, so, why the "1:1" thingy? There is no change in balanced antenna to unbalanced feed line, so, why the 'balance' thingy? By definition, a choke is not a balun at all. You can certainly call your cat 'Dog' if you want to, but it ain't never gonna bark...
- 'Doc

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