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OCF dipole

airplane1

airplane1

W9WDX Amateur Radio Club Member
Apr 15, 2005
1,051
32
58
Lebanon county PA
I am putting up an ocf dipole on my tower. The feed point will be mounted 30-35ft high on a non matalic side arm 24+ inches from the tower so it will not react with it I hope. The short leg will be 45ft and the long leg 90ft and mounted about 10ft high from the ground.

Now with that said, Can someone help me with which is the best direction to have it running. I guess it is a bit directional in the direction of the longer leg so I was thinking short leg running west and longer leg running east or very close to that. Or maybe short leg east and long leg west or ?

Please help me.

Thanks,
AP
 

Airplane1, the OCF dipole can show some directionality, but I don't think you are likely to realize that directionality at this frequency---with such a low height.
 
I am planning on using it on 80,40,20 as soon as I pass my general. So I wont see much if anything, Then I will run it the easyest way for my property, long leg west and short leg east. I hope to get over seas with it.

just above that for 10 meter I will be putting up a Maco M104C flat side which I made from an old shooting star antenna that was given to me and some of the parts were bent but had enough to build the 104. On top of that will be an A99. Hope it is a good setup.

I did not figure what to use on 6 meter, maybe the ocf because it should tune there.

Thanks Marconi,
AP
 
I think you would be best to put it up in such a manner that it is as high as possible, and away from other objects as much as possible.

With an tuner, you can use it on 60 , 30, 17, 15, 12, 10, and 6 also. You may need a tuner for 80, 40, and 20, too.

Are you feeding it with coax? You might also need a 1:1 balun.
 
I am feeding it with coax and a 4:1 balun. I do not have any trees or structures to get it up higher on the ends so 8-10ft will have to do. My tower is the highest object and I could go as high as 40ft with the feed point of the OCF I just thought it would be good at 30-35ft.

The only object close to it will be one end of the garage where it will be about 15ft above the edge of the roof. this is about the best I got right now.

I have lots of room on my property for what ever just no structures .lol
 
Highlander hit it on the nail head, get it up as high as you can.

I have read and studied the OCF and different variations of them before I installed one at my ham friends qth, he is visually challenged and needed an antenna that would work without tuning per say.

The OCf is tricky to tune on the frequency of the band you may want to work on. I have not been able to get the whole voice section or CW section of all bands to be acceptable vswr, so a tuner will definately help if you plan on jumping around the same band from one end to another.

The OCF works on current and does well where it is resonant, not great but it does well.

If looking for an multi band wire antenna maybe try a couple of fan dipoles, probaly get better results ouit of the fan than the OCF at the height you are installing it at. Either way both will be cloud warmers.

Another option is the all band doublet, ladderline and a 4:1 balun with tuner will cover all bands if you have enough room for a 160 dipole, tuner is required.

The all band doublet will throw a heck of a lobe in the same direction as the wire is installed on 20 meters. Works fairly well on 40 and 80 meters, just a dipole on 160.

If you got the real estate, and are willing to use a tuner, all band doublet imo speaking from experience having built and used both, is the antenna to go with versus an OCF.

Good luck on the upgrade.
 
It isn't a 'balanced' antenna, why would you need a balun? If you are going to use a balun, make it a 1:1 balun, the impedance range will be so varied with several bands that there's no real benefit from a 4:1 balun.
- 'Doc
 
I was just going by what info I got on the internet search for the ocf dipole said to use. I see 4:1 and 6:1 baluns used. I am copying sortof the buckmaster ocf 7 band dipole they sell for 200 + $. and I got a free 4:1 balun from LDG when I bought my AT-7000 tuner so I cant get cheaper than that. I now am getting confused, I guess I will just try what I got and see.

Thanks,
AP
 
W5LZ said:
It isn't a 'balanced' antenna, why would you need a balun? If you are going to use a balun, make it a 1:1 balun, the impedance range will be so varied with several bands that there's no real benefit from a 4:1 balun.
- 'Doc
Click to expand...

AIrplane DOC may have been replying to my post as I did not clarify why the use of a balun.

I use a short run of lmr400 to get the "RF" out of the shack and a 4:1 balun from the coax to the ladderline. So I mentioned the 4:1 balun.

You can run the ladderline into the shack and most tuners have a 4:1 balun built into them. thus no need for a balun at the antenna.

The OCF does specify use of a 4:1 balun in the construction. The OCF is not matching impedance it is matching current for multi band use if my memory does not fail me, which it might.

OCF Dipole Whoa! Holy Cow!

nice article on the OCF

Airplane build it and have fun, experimenting is the best part of the hobby.
 
Isnt it the Carolina windom "ocf" that used twin lead at the feed point to a balun then coax into the shack? Might want to try that route.

Do you have the room for a full wave loop?

Coax fed fan dipole would be a good choice also.
 
Yes plenty of room. 160 meter loop will be around 500-550 ft. A 75 meter loop will be around 240 ft. The one I have up now is fed with coax and a matching stub.It needs no tuner on 75, but for the other bands you will need a tuner.

If you dont want to use a tuner the fan dipole is a good choice. I have used one cut for 3 bands with great results.
 
Pick the lowest freq. your going to operate on, cut the length for that freq. Put it up with as much area inside the loop as possable. It doesnt have to be a perfect loop,it can be a square,rectangle, diamond, triangle or any combination. Mine is strung up in trees with no particular shape. The more area you have open in the middle the better it will work. I feed mine with coax 1/4 wave of 75 ohm and 50 ohm to the shack. If you have a tuner I would use ladder line for better performance on other bands. Google, full wave loop. lots of stuff out there.
 
thanks i'm looking on the net now. so it says loops are quieter than other antennas. does this mean they do not pic up signals as good as other types?

AP
 

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