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MFJ Moxon
- Thread starter Bearcat
- Start date
would it be possible to use the 15 meter mfj moxom and cut it down to 11 meters
Holy thread ressurection but the answer to your question is yes. All you have to do is scale all the lengths and spacings as needed.
Conor this member is new and maybe he does not know how to do the scaling of each wire in the Moxon.
Cliff Hanger are you planning to build the Moxon out of wire or aluminum tubing?
Try this free Generator for the dimensions for 11 meters. You will have to download this calculator.
Click here: http://moxonantennaproject.com/design.htm
Just enter the frequency you want and the wire dimensions as noted, push the button for Calculate.
Good luck and welcome to the forum.
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It tunes to 27.385 with the need for additional support. I used the measurements below. Your situation may vary.
A = 156 in
B = 21 1/8 in
C = 6 3/4 in
D = 29 7/8 in
E = 57 3/4 in
CH, I would use tba02's dimensions that he posted earlier. I did a model of his Moxon at 27.385 mhz and using the calculator I posted earlier. The model showed to be a tad short, so tba02's #'s being a little longer, are probably right on the money.
I assumed all elements were .50" inches in diameter in my model however, and that can make a little difference too...if the beam you buy uses a different diameter, use taper, or if they swag their tubing...which I know they do. My model did not account for any of these tubing differences, and it is possible tab02 didn't use similar sized tubing either.
Just be careful, watch you cuts, and test the match near the ground...before you raise it up to installed height.
I don't advise someone that tells me they are very new to all this...to start by modifying a multi-element beam antenna, but I will advice you to be very careful in cutting this 15 meter apart.
The antenna is not that complicated, but it has to be right.
Have you thought about the other stuff you might need to rotate your new antenna, or are you just flying by the seat of your pants, so to speak?
Your dimensions are posted already...if you want 27.385 as your center frequency.
Good luck and be careful.
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I have a cd ham 3 rotor and 100 ft of davis rg8x coax. When I said I was new to this I meant new to modifying antennas. I've had cb off and on since the early 60's. Original license was kpc-022. I wasn't trying to be a smart --- I only meant I had always used a antenna as they came from the manufacturer. Thanks for the help anyway
No cliff hanger, it is me that should apologize for appearing bossy. You should always follow your dreams and ideas.
Good luck,
Marconi
First off I know this is old and I am resurrecting it. With that I would love to say Homer BB I built a moon based on your plans. I thank you and all here who discussed this Moxon build in helping me get the courage to build it. I did deviate though from your plans and it turned out fine. Instead of having the gap at 7 inches I have my gap at 4 inches. Everything else is based on your Moxon that had the revised element length.
I built it from half inch aluminum tubing. I did not bend it but hammered the ends of the elements and used stainless steel bolts to fasten them together. I have a wood boom and the antenna is being used horizontally. It is at 30 feet above ground. It is 21 feet above a very large metal awning covering my patio.
I was concerned, after reading postings here, I was going to have to spend days tuning the antenna. Nope. First test with an SWR meter I had 1.1:2 pretty much across all 40 channels. I don't have an antenna analyzer so SWR meter for me until I get one.
After the first test I put it up over the awning in it's operational position. SWR did not change. I used a Bearcat 980 barefoot and was able to make some pretty good contacts in S. California from Boise Idaho. Over the next few days I have had short skip into Oregon and Seattle Washington. I had a station from Anchorage Alaska trying to reach me but there was so much chatter I could barely hear him. Others were nice enough to relay for me though. Hey guys, thanks for that.
I do have power to use if I need to but I am finding the Moxon with stock power is so much more fun. I have compared it to my quarter wave vertical I built and I get mixed results as to the beam being the better antenna. When conditions are right, and the other station is doing some flame thrower power levels both seem to pick the operator up. At other times the beam reveals a station that the vertical never knew was there.
Over the next few weeks I will be testing the antenna more. I am going to try to determine what my f/b is like and the s/b. Hopefully I do have a good f/b on the antenna. I am not sure because sometimes I am talking south to California stations and Seattle comes in and reports they are picking me up just fine. With stock output of my 980 I am curious about this?
A few questions if I may.
How did you come up with the 7 inch gap?
If you know what would be the difference between a 7 inch gap and a 4 inch gap?
I wonder if that may have a part in changing the f/b ratio?
As I recall from the discussions here the f/b was changed by adjusting the reflector length. Again I used your calculations as cut my reflector to those specification.
Again thanks everyone. I know this is resurrected but personally I enjoy reading resurrected posts because I may be needing to find that old information. I hope I can influence someone to build a Moxon based on the success stories posted here. I am having a ball finding out how well it works and that I can shut of my amp and run strictly barefoot and still get excellent signal reports.
My next project is to fix my Turner Plus 3 that seems to have died. That mic had me getting some really good audio reports.
73s to all of you.
I built it from half inch aluminum tubing. I did not bend it but hammered the ends of the elements and used stainless steel bolts to fasten them together. I have a wood boom and the antenna is being used horizontally. It is at 30 feet above ground. It is 21 feet above a very large metal awning covering my patio.
I was concerned, after reading postings here, I was going to have to spend days tuning the antenna. Nope. First test with an SWR meter I had 1.1:2 pretty much across all 40 channels. I don't have an antenna analyzer so SWR meter for me until I get one.
After the first test I put it up over the awning in it's operational position. SWR did not change. I used a Bearcat 980 barefoot and was able to make some pretty good contacts in S. California from Boise Idaho. Over the next few days I have had short skip into Oregon and Seattle Washington. I had a station from Anchorage Alaska trying to reach me but there was so much chatter I could barely hear him. Others were nice enough to relay for me though. Hey guys, thanks for that.
I do have power to use if I need to but I am finding the Moxon with stock power is so much more fun. I have compared it to my quarter wave vertical I built and I get mixed results as to the beam being the better antenna. When conditions are right, and the other station is doing some flame thrower power levels both seem to pick the operator up. At other times the beam reveals a station that the vertical never knew was there.
Over the next few weeks I will be testing the antenna more. I am going to try to determine what my f/b is like and the s/b. Hopefully I do have a good f/b on the antenna. I am not sure because sometimes I am talking south to California stations and Seattle comes in and reports they are picking me up just fine. With stock output of my 980 I am curious about this?
A few questions if I may.
How did you come up with the 7 inch gap?
If you know what would be the difference between a 7 inch gap and a 4 inch gap?
I wonder if that may have a part in changing the f/b ratio?
As I recall from the discussions here the f/b was changed by adjusting the reflector length. Again I used your calculations as cut my reflector to those specification.
Again thanks everyone. I know this is resurrected but personally I enjoy reading resurrected posts because I may be needing to find that old information. I hope I can influence someone to build a Moxon based on the success stories posted here. I am having a ball finding out how well it works and that I can shut of my amp and run strictly barefoot and still get excellent signal reports.
My next project is to fix my Turner Plus 3 that seems to have died. That mic had me getting some really good audio reports.
73s to all of you.
Earlier in the thread Marconi made the observation that of the variety of www generators the same antenna request gets different dimensions.
Here is where 7" came from.
Others give me around 4".
Here is where 7" came from.
Others give me around 4".
I have built a 10 Meter Moxon that is also adjustable to work on 11 Meters. Called the SE-10MB, it uses 5/8" and 1/2" aluminum tubing, and has enough strength to keep a horizontal position without the need for any bracing. I have recently modified it to use a SO-239 connector rather than a pigtail connection. It includes a balun and the usual PVC mounting plate to isolate the balun from the boom. Another modification was made to the boom-to-mast mounting plate. The plate bolts directly to the boom in either the horizontal or the vertical position. If you are interested, I can forward pictures of the mods and the VSWR curves for both 10 Meters and 11 Meters. I still show the old model on my website: www.sal-electronics.com. Just look up the Moxon products and go to the SE-10MB.
73, Mike
73, Mike
I made mine from half inch tubing and it worked out just fine. I wanted to reduce weight a bit. I know your project was from the walker and it is made from the 3/4 inch tubing. I was out at yard sales and saw some tent pole tubing. They wanted $3 for a bundle of tubing that would have made several antennas. It was pretty thin walled 3/4 like you had. Silly me I did not buy the tent pole tubing. Lucky though there is a metal shop in town that sells aluminum tubing. It was much thicker wall and a bit heavier so I stayed with half inch to reduce weight. I wanted some 3/8 inch but he did not carry that in stock so half inch came home with me.
I am having so much fun with this antenna. My neighbor does want me to move it out of her sight. HOA here. She is pretty nice about her request and she isn't going to the HOA. Meanwhile I am looking at where I will move it to on my house. Lucky me it doesn't weigh much so relocating will be pretty easy.
I took down my quarter wave vertical she frowned at but tolerated to ease her pain. I did rebuild a version of it which is much less visible to her yard. I admit the one I took down did stand out a bit. Boy oh boy it sure could talk though. I hope my new one will do as well. No one was at thier radio today so it was hard to test.
73s
KC9Q. Very helpful . I put my Moxon up today. Used the measurements for 10 meters. It seems to have the lowest set at 29.2 MHz. I’m going to adjust it out tomorrow as far as I can safely.
The swr in the 11 meter band was 3 and up. Also it is only 20’ in the air. I will raise it to 33’ when my rotor shows up. Gonna test the receive tonight a little. . I am interested in insulating the boom from the reflector. Please send info to Donnydobbs@yahoo.com . Thanks
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