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Thread: DB-420 16 bay UHF folded dipole.

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  1. #1
    Conch Master W2NAP's Avatar
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    Quote Originally Posted by kb2vxa View Post
    Oh stop complaining and let's get back to the subject. If you're having so much trouble mating 75 ohm connectors with 50 ohm ones, why not go 75 ohms all the way? 75 ohm coax terminated with a 50 ohm pure resistive load will give a 1.5:1 SWR. Since every antenna has some reactance, a good match is usually 1.2:1, so in any case the end result is always well within acceptable limits. I've seen hams using CATV hard line spool ends with excellent results, the extremely low loss characteristics more than make up for a little SWR, VERY little BTW.
    AH, if this was just a run of feedline I would. but since this is a phasing harness doing so could actually mess up the phasing. all the phase harness is 75 ohm rg-11. with 75 ohm (N) connectors. I have been told to keep the interconnect between the 2 sets of harness 75 ohm connectors or bad things happen end up with a impedance bump..

    http://www.commscope.com/catalog/ima..._r01645_v4.jpg is the type of Antenna (still unsure of who actually made it) TKX posted a link to the antenna type.
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  2. #2
    Whacker Knot WØTKX's Avatar
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    "Where would we be without the agitators of the world to attach the electrodes
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  3. #3
    Whacker Knot WØTKX's Avatar
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    Yea, the phasing harness lengths are critical. It has to do with getting the timing right with a carefully trimmed length of a cable with a known (preferably measured) velocity factor. Knowing it's RG-11 helps.

    That being said, a single 50 Ohm connector in a 75 Ohm harness would probably not change too much. You could modify the harness slightly to accommodate the small change... and you'd have to measure it.

    Much simpler to get the 75 Ohm connector. But I wonder how much it would change?

    Every harness I have made I used extra coax and connectors, cut and measured a few till I got it just right, and then made 'em. So far, just two meters, and the MFJ analyzer showed me what was going on really well.

    Modified the 2m loop design from this page, for a pair of 2m loops...

    http://www.kr1st.com/2mhalo.htm
    "Where would we be without the agitators of the world to attach the electrodes
    of knowledge to the nipples of ignorance?" ~ Professor "Dick" Soloman



  4. #4
    Conch Master W2NAP's Avatar
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    I figure its best to leave the harness with what the guys at the factory used.. Those guys that made this thing are a shitload smarter then I am lol.

    I guess a center pin will turn up eventually or ill just have to scrape more cash from somewhere and buy a damn replacement connector..
    I AM THE VOICE OF THE VOICELESS!

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