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Post by BladeRunner now OLD FLASH!!!!! on Sept 22, 2009 15:54:01 GMT -5
I got an excellent deal on a 6 elment MACO yagi. it's still in the box and never used , but the instructions aren't there. I looked on the net for instructions but none met the way this antenna looks right. The five front elements are verticale aluminium elements but the rear element is the two element (two vert. two horiz) fiberglass with the wirw arounsd the outside of teh tips of the elements. I have no demensions or lengths and need to know what they are to be able to put them together correctly. Anyone ever seen or had one of there and have the demisions? Thanks
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Post by Joe on Sept 23, 2009 16:20:06 GMT -5
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Post by BladeRunner now OLD FLASH!!!!! on Sept 29, 2009 18:38:01 GMT -5
I appreciate the reply Joe. I got the plans and have the antenna assemblrd in my back yard. I have one problem. It;s Gigantic!!!!! II have a lot of reading and I don't even think I have enough room if I were to strip all the trees on the side facing the antenna. For you antenna experts out there. I got this antenna for a song. Virtually nothing. It's new and has never been up. I'm thinking of cutting it down and making it either a 4 or 5 element beam out of it. I've looked at all the Maco plans and the 5 element still has a pretty long boom and I'm not sure that will even fit. WHat I'm concidering is a 4 element, but still utilizing the three wire reflector. From what I read, All the reflector is for is to make it extremely directional and have much more front to back rejection.
I wonder how it would work if I used the plans For the M104c or the shooting star (which is a horz/vert version of the M104c. THe boom length difference between their 4 and 5 element beams is that the 5 elemetn boom is 10 feet longer than the 4.
Now, I've done a lot of reading about DIY antennas and Yagi theory. Mainly the greater the boomlength and greater the seperation of the elements, the more directional it is. I wonder if I could shorten the regular boom length of the 5 element and put the first and second elements (from the front) closer together and if that would work. Anyone have any ideas on the subject? I'm still looking and thinking and welcome any ideas.
BR
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Post by Marc on Sept 30, 2009 15:26:47 GMT -5
In the past I have seen many multiple wire reflectors.
Evan saw one with chicken wire covering hole backside of a Moon Raker 4 lol.
none of them added to the rejection or gain of the antenna.
But they did radiate harmonics. IMO I would remove the two inside wires and run only the outside one. Could create TV or RFI
in your neighborhood. And thats not good!!!
Marc
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Sandbagger
Administrator/The Boss 
Posts: 6,250 
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Post by Sandbagger on Sept 30, 2009 16:19:20 GMT -5
In the past I have seen many multiple wire reflectors. Evan saw one with chicken wire covering hole backside of a Moon Raker 4 lol. none of them added to the rejection or gain of the antenna. But they did radiate harmonics. IMO I would remove the two inside wires and run only the outside one. Could create TV or RFI in your neighborhood. And thats not good!!! Marc The adding of additional wires to a quad reflector for additional gain and/or rejection is one of the oldest myths around the CB band. The idea seems straightforward enough. If one wire will give you "X" amount of gain, then adding more wires will boost that number. It's the old "more is better" philosophy. There's only one problem, the length of that one wire is cut for a critical length, based on the dimensions for a quad reflector at 27 Mhz. Adding additional wires at different points on the spreaders will become resonant at a different (usually higher) frequency, which will do nothing for you. I've seen hams uses multiple wires on their quads for precisely that reason, they use the same boom but have multiple frequency bands based on the length of each set of quad elements. Covering the entire "+" reflector element with chicken wire completely changes the characteristics of the reflector. At that point it is no longer a quad, and becomes a simple yagi parasitic element, or more like a corner reflector. But without proper modeling, it's tough to predict just what the effect will be. It's a good bet that it will end up worse rather than better..... |
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Post by BladeRunner now OLD FLASH!!!!! on Oct 2, 2009 16:39:14 GMT -5
I appreciate the answers but by the time I got back here I had read all of what you have said out "all over the net" the multiple wires really hurt the signal more than help. What I have decided to do is take the maco flat 6 and make it a 5 element without the wire reflector. I would use the wire reflector but don't know how that would effect the dimensions of the rest of the elements. Better to play it safe and go with the M105c dimensions. I'd like to use the wire reflector but it wouldn't be easy to change if it didn't work out.
Oh , one more question htat the instructions don't cover. I have the 5kw connector on the gamma match. The instructions only show the one with the pl259 connector. hte 5kw connector is ceramic that's tapered on one end and has bolts and nuts on both ends... don't know which one to put the center core on and which to put the shield on. I may juts use the gamma match that's on my Maco 3 element. Maco antenna support says tjey are interchangable, but they have no answer about the 5kw connector
Thanks Guys
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Post by Marc on Oct 2, 2009 17:49:59 GMT -5
The quad reflector will be the same no matter how many elements you have. put it together the way the instruction say and keep the same spacing from it to the driven element and you will be fine.
As far as the 5KW connector, I have no idea but I am sure someone here has worked with it before.
Marc
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Post by BladeRunner now OLD FLASH!!!!! on Oct 3, 2009 16:42:07 GMT -5
Thanks for all the help Mar and everyone else. I have one other question though. WHat I'm after is to have the best reception possible (ears LOL) would the quad reflector make that much difference over having a normal vertical element reflector?
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Post by BladeRunner now OLD FLASH!!!!! on Oct 4, 2009 9:32:45 GMT -5
The covering the wire reflector with chicken wire plus putting more than the critically measured single wire configuration gos back to the old human belief that if a "little is good" "more has to be better" If you think of it logically though , the instructions go over and over the importance of the outer wire being "exactly" correct in length, It's not logical just to randomly throw on two more wires. It just maks no sense. At least to me.
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Post by BladeRunner now OLD FLASH!!!!! on Oct 4, 2009 11:16:45 GMT -5
A picture is worth 1000 words. This what I'm talking about on the Gamma Match. Which wires go to which end. img209.imageshack.us/img209/7765/10000692.jpgOne last question. I think I know the answer to this Thanks Al, but don't hurt to have a second opinion. l currently have a Maco 103c up and have the gamma match adjusted so I have 1.1:1 swr. If I were to move this to the 5 element. What are the chances the adjustment eill be close to having as low an SWR as I have on the 3 element? |
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Post by BionicChicken on Oct 4, 2009 20:03:08 GMT -5
Bladerunner, This setup is the best you can have as far as connection to the gamma match is concerned. The center conductor of the coax goes to the screw which goes through the ceramic insulators and attachs to the gamma itself. The braid (shield) of the coax will attach to the element clamp itself.
I use the same hardware on my antenna (M107) with a 10K gamma match. Never had a problem with it. Once you connect it all up get something like ScotchKote or either liquid electrical tape and coat the entire connection several times allowing it to dry in between coatings. Tape the coax where the braid and center conductor insulation are separated and then apply the sealant there also. It will protect the coax and eliminate the possibility of water entering the coax at this point.
As far as the SWR being the same I wouldn't bet on it. Each antenna is different. However you might get lucky and be close in the ballpark. It is a good idea to tune every antenna for the best possible reflected power across the operating range you will be using.
Holler if I can help out in any way.
BC
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Post by BionicChicken on Oct 4, 2009 21:56:09 GMT -5
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Sandbagger
Administrator/The Boss
Posts: 6,250
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Post by Sandbagger on Oct 5, 2009 7:17:50 GMT -5
And that is exactly right. |
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Post by BladeRunner now OLD FLASH!!!!! on Oct 7, 2009 22:05:00 GMT -5
Thanks BK. I had already read the info at signal engineering . I'm not going to use the wire reflector because the distance between the driven element and the reflector are a lot different that ones that just use an element reflector. I've assembled the antenna to the exact measurements of the M105c. I hated to loose that last element but I just don't have he room. If I put the wire reflector on it I'm afraid I'd run into problems because of the different element seperations between the two types of configurations. THanks again... hopefully this weekend it goes up
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