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Flush
Junior Member
Username: Flush
Post Number: 16
Registered: 11-2006
| | Posted on Tuesday, February 06, 2007 - 1:26 pm: | 
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Ok I think im going to try a di pole antenna. I have a 102" on a 6' step ladder that works "ok". Get about a 2:1 SWR however my receive is poor. Im going to try a make or buy a dipole. How much watts can these handle and is there any tips on these? Do these work better in the attic or along a roof line such as next to the rain gutter? Could it be placed a few inches above a tile wall? What would the total span be?
This radio bug is addictive! :-)
Thats a good thing!!
Aloha |
Doughboyx
Junior Member
Username: Doughboyx
Post Number: 34
Registered: 9-2005
| | Posted on Tuesday, February 06, 2007 - 10:06 pm: |
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Flush
I have built mine and the receive is very go locally but the transmit its not that good. Maybe about 15 to 20 miles. Like the old saying goes height is every thing. I believe if I was able to put it in the tree behind me about 25 to 35 ft then it would do better.
I did a search on google and found all the info. Using #14 gauge wire or bigger as far wattage goes as much as your coax can handle with no problem. |
Ronin
Member
Username: Ronin
Post Number: 55
Registered: 8-2006
| | Posted on Wednesday, February 07, 2007 - 2:32 pm: |
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As Doughboyx said.
A dipole will work fine and the higher the better.
I have an inverted V dipole for CB and 10 meters in my attic and it works well considering that it is only about 17 feet at it's feed point.
If you are looking for omni-directional coverage, mount the dipole either vertical or in an inverted V. If you mount it horizontal, you will have a fair amount of attenuation of the vertically polarized signals and it will be directional on the broad sides in both directions.
As for length, about 17 ft. 3 inches over all and each leg should be about 8ft. 7.5 inches. Always start with a longer length (about 9ft on each leg in this case) and trim it down as needed while checking with an SWR meter. Mine is a 1.1:1 at 27.205 and stays below 1.3:1 across the CB band. It should be useable for about 1 Mhz bandwidth or so, so take your swr measurements in the center of your operating area.
One final note. If you be feeding the dipole with coax, tt will help to make a coaxial balun to keep any stray RF off of the feedline (refered to as skin effect). Just wrap about 5 or 6 turns of RG-58 or RG-8x coax into about a 5 inch diameter circle right near the feedpoint of the dipole and tape the turns together or use wire ties. You can then solder the coax directly to the dipole legs. If the dipole will be outside in the wind and weather, make some kind of strain relief for the wire of the dipole and the coax. A small peice of plastic will do fine and tape or wire tie the wire and coax to the strain relief.
Good luck!
Jim
CEF-813
K3ZOR
OT-235
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Ferd1605
Junior Member
Username: Ferd1605
Post Number: 28
Registered: 1-2005
| | Posted on Sunday, February 11, 2007 - 11:25 pm: |
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Another thing bout a dipole ... the SWR's will change if you have a V configuration , you can move the V tighter or less of a angle will change the SWR's .. If you want to talk local , you should be vertical with the whole antenna for best results , and if doing that , the coax needs to run away from the antenna at a 90 deg. angle for atleast 1/2 wave length and use the coax RF choke Ronin advised .. good luck |
