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Stacked M103C vs 5 element/7 element

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  #1  
Old 09-09-2007, 09:38 PM
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Default Stacked M103C vs 5 element/7 element


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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Old 09-10-2007, 01:36 AM
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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.
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Old 09-10-2007, 11:49 AM
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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:
Quote:
Originally Posted by distortion
How would this perform in comparison to say a 7 element Maco, or a 5 element Maco.
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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Old 09-10-2007, 02:48 PM
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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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Old 09-10-2007, 05:01 PM
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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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Old 09-10-2007, 08:53 PM
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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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Old 09-10-2007, 11:08 PM
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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.


The driven element uses a hairpin matching network.

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

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Old 09-29-2007, 11:50 PM
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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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