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Thread: paralell coax lines, bad?

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    paralell coax lines, bad?

    so i have been studying some pictures of comp suburbans to see if there is something i missed as far as setup. no difference from mine from what i can see except for one thing. i noticed all the coax runs are kept separate from each other, no one coax line is running parallel with another coax line. is this important to do? i have my jumpers running parallel and zip tied to each other and the main antenna line. is that bad?

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    Never ran into a situation where it made a difference...For as that go's, my beam is a dual polarity beam meaning it has vertical and horizontal elements all on the same boom...Which means you have to have two separate coax runs to the antenna...Be kinda hard to keep the coax separated running 50' up the side of a tower, and then back into the house...

    I just imagine the reason guys separate the coax runs in their Burb's has to do more with it being easier to run one coax under the rocker panels than trying to cram two coax cables under the rocker panels...plus it helps identify which coax go's to the input and which go's to out-put if you have them running on opposite sides of the truck.


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    BOOTY MONSTER (08-09-2020)

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    ok cool. it gives a nice clean look when they are paralleled in the burb. but im gonna separate them anyway just in case i have common mode current issues. i dont want any capacitive coupling from one line to the other.

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    JesseJamesDallas (08-08-2020)

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    I've found long ago that physical placement meant very little and coax impedance and length are foremost. dual antennas should be fed with equal lengths of 18 feet, RG-59, not RG-58. Two parallel lines of 75 ohms is equal to 37 ohms, easier to match than two 50 ohm lines at 25 ohms impedance. However, if the lengths can be expanded to a full wavelength, the 50 ohm RG-58 will work good. Base setups can benefit from better coax like RG8 or RG-214,

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    Quote Originally Posted by mjd420nova View Post
    I've found long ago that physical placement meant very little and coax impedance and length are foremost. dual antennas should be fed with equal lengths of 18 feet, RG-59, not RG-58. Two parallel lines of 75 ohms is equal to 37 ohms, easier to match than two 50 ohm lines at 25 ohms impedance. However, if the lengths can be expanded to a full wavelength, the 50 ohm RG-58 will work good. Base setups can benefit from better coax like RG8 or RG-214,
    That's only if your setting up co-phased antennas...If your going for something like "2-Hot's" or bounce-back set-up like guys rig up on top of suburbans, then you use 50ohm coax...Spacing is more critical on these set-ups to get the right signal patterns, and if your going with 2-hots, then the length between the two antennas is also critical...

    just all depends on what your going for.


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