Moxon for 11 meters

[Bow]

Actually I have read that the MoxGen dimensions seem to be a tad long, so the center Freq tends to be lower that planned...

I spec'ed it out at 27.555 with 0.5 in Copper

it gives me This:

I wonder if I should Spec it for 28 or 27.750 Mhz.... since there isn't much information on tweaking the antenna, after the fact...

28 Mhz gives a "A" of around 152" or 12.6 feet...

I believe Homers last one, made from a recycled walker, measured out like this:

(Image acquired from Mauldroppers)

 

[vkrules]

You alter "b" and "d" , same both ends not "c' How you do that with 1/2 inch copper is up to you.Me I would make the frequency a little high and fit wire stubs to b and d that way you can play with the reflector length as well .

 

[vkrules]

Back to an earlier question about what to use as a boom. I saw some nice fiberglass shovel handles at the local hardware that would work great.A quick walk around your local I'm sure you would find something.Time to stop looking at computer models and start building.

 

[Bow]

Thanks VK

I just got done cutting all the copper. I fitted the Elbows and caps before measuring, so my measurements are "Outside to Outside" as opposed to "Center to Center"

I may just tac-solder it to try it on the Antenna analyzer, and if it is good solder it all the way up.

I also picked up some Aluminum Angle for the center support/Boom Mount and have some material to isolate the boom from the elements...

I'll be slinging solder after dinner! I can think of worse ways to waste $50 if this doesn't work! LOL

 

[M0GVZ]

Back to an earlier question about what to use as a boom. I saw some nice fiberglass shovel handles at the local hardware that would work great.A quick walk around your local I'm sure you would find something.Time to stop looking at computer models and start building.

Be careful of anything plastic/fiberglass that looks like it will do the job if its primary use is something else that requires having some strength to it. I saw some plastic rods which are commonly used in the UK for putting temporary fencing up which looked ideal.

Built my Moxon from them, found I couldn't tune it. When I cut into the rod it was actually metal tube with a plastic coating.

 

[HomerBB]

The graphic above is representative of the Moxon I am currently running. I do think that the discussion Marconi and I had about it resulted in very close agreement between his models and my results with the real-life antenna. However, the results I have were gathered from where my MFJ-259B analysis showed the center frequency to be. The key thing about this antenna that ought to be remembered when using it is that it is so wide-banded compared to any other 2 - 4 element Yagi I've used that being dead centered on the frequency of choice is much less an issue for practical use.

 

[Bow]

Well, I got it on the roof....

The lowest SWR is 1.7:1 on my target freq of 27.555

I'm betting the proximity of the house (2 story house, 1 story garage roof) is what is killing me...

well, I might be better off sticking with the 1/4Wave GP....

But like I said, $50 in copper is better spent trying to build an Antenna then say.. drinking it...

I might have to try the Phased Verts instead... I have a couple of 102" whips and few morals.....

 

[Henry HPSD]

Hello Bow,

Dont give up m8.
For sure the objects will have influence on SWR etc.

Though it still should be possible to get a decent SWR.

Do you have pictures of your project ...

Once you are used to horizontal directive antennas, there is a new world out there !

 

[Bow]

Thanks Henry,

I Have and antenna tuner, and I have it pointed North East (no rotor), I'll give it a try to Europe tomorrow and see how it goes...

 

[sp5it]

Well, I got it on the roof....

The lowest SWR is 1.7:1 on my target freq of 27.555

You need to put it higher.
Mike

 

[222DBFL]

Get that thing up to at least 25-30ft, preferably closer to 40ft and it should would well like every else has posted, I know when I installed my dipole in the back yard a move from 18ft to about 30 ft made a big difference and it didn't cut my local talking out either, best of both worlds, could dx with a barefoot uniden pc122xl around the world with a 2 dollar dipole I made from scrap cable and a bad swr meter so-239 connector. Like said don't give up, trouble shoot the issue until it's resolved, then sir back and enjoy something you made that works!! God bless and hope you get it sorted. Also when I moved my dipole up it did help the VSWR Settle down. I made an air choke with my excess coax, which helped with balancing my impedance and also keeps my swr reading at 1.0-1.15 across the chicken band.

 

[Henry HPSD]

Ah there is mike again....

Did the pdf's help mike ?

Kind regards,

Henry

 

[sp5it]

Yes Henry, but in real world exactly what i said. Antenna is too low over the mounting place.

 

[Henry HPSD]

Hello Mike,

Oke, yes of course it is.
As earlier mentioned:
SWR is easily influenced by obstacles in the near field.

I was however under the impression you were referring to TAO, as the conversation had that point as subject.

Perhaps we were discussing two different things hihi.

Kind regards,

Henry.

 

[Bow]

You need to put it higher.
Mike

I wish that was an option...

Get that thing up to at least 25-30ft, preferably closer to 40ft and it should would well like every else has posted, I know when I installed my dipole in the back yard a move from 18ft to about 30 ft made a big difference and it didn't cut my local talking out either, best of both worlds, could dx with a barefoot uniden pc122xl around the world with a 2 dollar dipole

I realize 100% that height cures issues gents, but that is something I can't do... I've been talking all over with a 1/4 Wave GP antenna at this same height...

I made the RF Choke (Coax, 10 turns, 6"diameter) at the feed point as well when I first put it up...

I am wondering if the way I mounted it to the boom is causing an issue... The elements are electrically isolated but the U-bolts going over the isolated elements are not isolated from the boom....

I'll try to get some pics in the daylight today....

if the Moxon doesn't work, I'll take it apart and I have enough copper for the 11M J-Pole! and they work well low mounted....