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Stacked M103C vs 5 element/7 element

Discussion in 'CB Antennas' started by distortion, Sep 10, 2007.

  1. distortion

    distortion Active Member

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    I have 2 sets of m103c's, and I'm considering getting a stacking boom and putting them up on a tower about 80' up.

    How would this perform in comparison to say a 7 element Maco, or a 5 element Maco.

    Would it be wiser to just get a 7 element and ditch the 3 element's? Or would the gain be more using 2 103's?

    Thanks,
    Josh


     
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  2. W5LZ

    W5LZ Crotchety Old Bastard

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    All things considered, I doubt if there would be enough difference to notice. Of course there would be some differences, but I think it would be more a matter of the optimization of the two individual setups. And, since you've already got the tow '103's, why not? After trying the stacked 103's, if you don't like them, then do the seven element. Personally, I don't think the difference in cost would be worth it, but then, I'm cheap anyway.
    - 'Doc
     
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  3. Master Chief

    Master Chief Guest

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    This is only MY educated opinion......

    A 3-element beam will give you x amount of gain and predictable signal pattern. Stacking a set of 3-element beams will give you 3db more gain, with about the same signal pattern. Stacking beams has its own set of problems mechanically.

    A larger beam (5 to 7 elements) will give you MORE gain and have a tighter "killing field" (pattern).

    You asked:
    You would have less gain and a bigger pattern, but would work just fine!

    I feel a 5-element beam is the antenna of choice. While 6 and 7 element beams will give you more gain, they are longer, heavier, and harder to work with. Unless you know what you are doing, you can actually degrade the performance of a beam by adding more elements.

    Tests have proven that people would get better results by REMOVING one of the elements from a Cushcraft 11-element 2-meter beam and re-spacing them on the same boom. Yep, the 10-element outperformed the 11 element on the same boom!

    5-elements on a longer boom works better than 5 elements on a shorter boom.

    There are a number of ways to get gain. I always recommend buying the best antenna and COAX you can afford. If you need more gain, use a clean amp.

    I'll have more to follow! I need to snap a few pictures first!
     
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  4. davegrantsr

    davegrantsr Active Member

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    5-elements on a longer boom works better than 5 elements on a shorter boom-well, yes and no. would you prefer BETTER rejection with less forward gain, or the other way around? 'optimally' spaced is just that-the most amount of gain WITH the most amount of rejection. BUT it WON'T be the MOST of both. oversimplification, maybe, but 1. you get the picture and 2. don't want to confuse distortion....if he had to ask, then let's keep it simple.
     
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  5. hotrod

    hotrod Well-Known Member

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    both setups have downfall
    the 5-7 elemnt beam will need a BIG rotar to tun it
    a stacked set of beams have the same complcations as sigle but now its double.with stacked set think ya need 2 rotars
    [i think]if so then double rotar wire ,ect.personally i think
    a 3 elent beam on flatside is a good lil dx antenna.but if
    ya have 500.00 to shell out for a new ham4/5 rotar then go
    ahead and get the bigger beam.just my opion guys
     
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  6. Captain Kilowatt

    Captain Kilowatt Professional Amateur Staff Member

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    You don't need two rotators for a stack. The antennas are connected to a horizontal stacking boom if mounted vertically and simply one above the other if mounted on the flat side. One rotator is all that is needed.Stacking two antennas side by side involves a lot more forces then you would think. Personally I would go with a sinlge 5 element yagi. The differance will be minute.
     
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  7. Master Chief

    Master Chief Guest

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    Yes Dave, more gain on a longer boom and still able to maintain a good f/r. All the big guns run longer booms......I wonder why?!

    I purchased a M2 11M5DX. You can see some of the preliminary pictures here:
    http://www.worldwidedx.com/gallery/11M5DX

    This antenna will beat a pair of 103s.

    This is 5-elements on a 26.7' boom. The gain is 8.3dBd with a front to back of 24dB. The specifications say it will take 1500 watts; the balun is rated for 3KW, and the instructions say it will do 5KW; so which one is right? The only limiting factor on this antenna is the balun. Replacing the stock balun with a 10KW balun and this antenna would easily handle a full 10KW.

    The driven element makes use of teflon insulators to prevent arcing between the element and the hardware. It is supported by a 15" solid fiberglass rod.
    [​IMG]

    The driven element uses a hairpin matching network.

    I have a new Maco 103 and will snap some comparison photos.
     
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  8. distortion

    distortion Active Member

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    Bought a m105c today for real cheap and finished assembly last night! It's on a 17 foot pole right now on my 12 foot deck, so it's 29 feet to feed point right now just to tinker.. I could raise it up 15-20 feet more, but would rather not.

    Thanks a ton for your advice. The 26' boom is not that bad at all. Can't wait to get me a tower up and a rotor, etc. I can tell already this thing is gonna be beastly.

    Thanks,
    Josh
     
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  9. KingCobra_CDX882

    KingCobra_CDX882 W9WDX Amateur Radio Club Member

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    the longest boom you can handle putting up (have space for etc)
    is the best choice
     
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  10. distortion

    distortion Active Member

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    Raised it up about 5 more feet so that it is a total of 34 feet to the feedpoint right now, and I gotta say.. That is half the height of my i10k which is 77-78' to feedpoint.

    The 5 element beam destroys it.. by a solid 2 S units, even with it being this low.. I can't wait til it's on a 80-100' tower :)

    For comparison's sake.. my i10k with a 2 pill on it was a pretty similar output as my beam barefoot on a 142gtl at half the height. Receive were about 2 S units difference as well.

    The i10k is a hell of an antenna for an omni, and it actually is comparable to alot of the 3 element beams around locally... but this 5 element is ill.

    I'm probably going to sell my i10k for the simple fact that everyone I use my omni to talk to anyways is within 5 miles and easily heard on the beam.

    Peace,
    Josh
     
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  11. Marconi

    Marconi Supporting Member

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    In Atlanta? That covers thousands of square miles, and with a I-10K at 77', and now a 5 element beam up, and you only talk to guys about 5 miles away? With a group that close you could talk to them on a dummy load.

    I'm in Houston and currently the closests guy to me is about 6 miles away. How can you really tell anything about either antenna at that close of a range? Within that 5 mile range your I-10K is likely talking right over the heads of most of your buddies. The real test of your beam will be out in the 50-150 mile range even at 34' which is not really a bad height for a beam.

    Something ain't quite right with this picture. Distortion, what are you trying to accomplish with your station talking in that limited range?
     
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  12. distortion

    distortion Active Member

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    We shootout a lot. It's a difficult situation to explain. It is misleading to say 5 miles, because a lot of the guys me and my neighbors (some less than a 1/4 mile) shootout to are 15-20 miles away.

    However, my main concern was that I would have a hard time hearing people east/west of me when pointed south. However, most of these people are running 6/8 pills and antenna's at extreme heights, so I was happy that I could talk to everyone around me within 5 miles.. while I was shooting straight south, but with that kind of power I don't suppose I had much to worry about.

    My gain of 2s units was pretty spot on for folks in griffin, and hampton about 15-20 miles away.

    I am not talking over these guys, in fact, I wish I had more height on the i10k, as I am in a hole :(

    I'm sure theres still holes in the story, but if you have any questions shoot away.. I haven't been to bed yet and went in at 9 last night, so I tried to answer the best I could :) lol

    Again, thanks for the advice on the 5 element. In comparison it now seems stupid to go w/ 2 3 element's as the 5 was a lot less hassle.

    Josh
     
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  13. Marconi

    Marconi Supporting Member

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    Well I didn't want to say it, but that is sorta' what I thought.

    The guys that do that around here do it with mobiles, so they can find themselves hot spots to contest from, and cut down on the neighbor problems. You probably know that location can really make a difference if you really want to be heard.

    There used to be one guy here locally that went by the handle EW that did the shoot out kind of thing. I use to go by Old Grandpa in those days and I called him Ego Willie. It pissed him off big time and he would not talk to me at all. I know for a fact that he spent hours and hours searching for hot spots all over north Houston and then maping out just how his hot spot radiated best. He wanted to know where that spot radiated best to and to which stations it affected best.

    In the course of an evening on the air he usually started working from his base and if things got hot, he would disappear for a bit and then show back up again stronger than ever working his mobile. He would holler when he came back on the air that he had a phone call. If he discovered that he was still getting beat, he was known to even drive over under someone's antenna to stop him from hearing, and claim all the time that he was on his base. This guy just had to win at all cost, and it cost him plenty.
     
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  14. Master Chief

    Master Chief Guest

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    You're welcome. Are you running this antenna vertical or horizontal?
     
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  15. Marconi

    Marconi Supporting Member

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    If he is doing the power thing locally, I'd bet he is vertical.
     
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