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Old 12-20-2011, 11:11 AM
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Kamakiri Kamakiri is offline
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Building a 2 meter 1/4 wave ground plane....

Picked up a 2 meter rig cheap on eBay, figuring that it's high time to get back on the amateur airwaves .

I was looking for instructions online on how to build a 2 meter dipole, and came across this:

I tried building some 2 meter dipoles and a coaxial dipole about 20 years ago, and never had much luck in getting them to tune properly. A much easier antenna to build is a 1/4 wave ground plane. All you need to build one is 5 pieces of stiff wire- each about 20-21" long (old wire coat hangers work great) and an SO-239 socket. Much simpler, doesn't need a balun.

Take 4 of the wire pieces and use needle nose pliers to bend 1 end on each wire into a small loop. Use a small machine screw through the loop to attach each one of the 4 wires to the chassis mount holes in the SO-239. Bend the wires so they point down about 30 degrees. Take the 5th wire, solder it to the center pin of the SO-239. Connect PL-259 connector on coax the the SO-239. That's it! Trim the vertical element for minimum SWR, final length should be close to 19". Should also work on 440 as a 3/4 wave antenna, although the radiation angle will be kind of high.

You can stand it up on the floor in the attic on the ground plane, using the 4 radials as "legs". Or use some electrical tape and fishing line and and hang it from the rafters by the vertical element. When I lived in a duplex, I has one sitting in the attic for years and never had a problem with it.


Decided to give it a whirl. I'll let everyone know how I make out. Going to pick up an SO-239 today and finish it up.

Question though, am I going to need to strip the thin clear plastic coating off the hangers, other than at the contact points?

And, does anyone have instructions for a simple 2 meter dipole? With the way I want to set the radio up, it'd make a lot more sense......
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Old 12-21-2011, 01:59 AM
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No, you will not need to remove the coating except where you will do the soldering.

I have never tried to make a 2m dipole, since dipoles are more typically used for horizontallly-polarized signals and 2-meter FM is vertical (therefore, the ground plane is a better choice). You could make a simple one with two ~19" pieces of wire connected to the center and outer conductors of some coax, but I have no idea what kind of signal you will get. 73
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Old 12-21-2011, 06:57 AM
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Got it done last night. Not half bad! Achieved an SWR of 1.6....not perfect, but I won't fry my finals. Got full quieting into the local repeaters, and even with it hung on the basement ceiling I was able to talk on simplex about 10 miles away easily.

Hung it in the attic crawlspace, and ran RG-8 down to the basement. Caught the end of the Western District Net, the local relay for the ARRL National Traffic System. I used to run several of the nets about 20 years ago. Glad to see that it's still around.

I'm back on the ham bands!


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Old 12-21-2011, 11:11 AM
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I've used similar antennas for years - simple and effective. The 21" recommended in the instructions seems a bit long. If the SWR is better at the low end of the band (144 MHz), trim and inch or so off of everything and I bet it will fall right in place. That antenna should have an almost flat SWR across the whole band.

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Old 12-21-2011, 02:56 PM
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That's what I was thinking. I knew that it was a bit too tall, but where the antenna is at the moment in the crawlspace, will have to get moved anyways when the Christmas tree is put away.

That aside, I plan to have one of my local friends who's a ham help me do the fine tuning. It was enough "fun" having my fiance help me run RG-8 through the wall last night
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