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Gerowen
01-14-2015, 04:03 AM
So I just built my first dipole antenna, and I have a question or two.

Do I need to give it some sort of earth ground, since the "shield" element will be suspended in the air just like the "hot" element?

Would 14 gauge stranded copper wire be able to handle 300 watts PEP on SSB, and 150-175 watts on AM? I normally just run 4 watts on AM, and 12 watts PEP on SSB, but if possible I'd like to work a little bit of DX, and 14 gauge is the heaviest wire that I had enough of to work with.

Also, I'll give you guys a description of how I built it, and if you don't care, tell me if I royally screwed something up. I've tested it and it works, even inside my house, but I'm just curious if there's anything I can do better.

I took the SO-239 connector out of an old junk CB radio and pushed it through the hole in the center of the clear protector that comes on a spindle of burnable CDs. I attached one wire to the shield and one wire to the center conductor with solder, pulled them in opposite directions, and then piled hot glue all over that side of the connector to protect the connections from moisture/corrosion. The clear CD serves to keep rain from directly touching the feedline and the female side of the SO-239. I used 14 gauge stranded copper wire that I had for making/repairing CB radio power cords. I cut the wires at 9 feet 6 inches each, for a total of 19 feet total, but then I folded back 5 inches of each element for a total of 18 feet two inches, or 9 feet one inch on each one. I folded them back and taped them with electrical tape because I was told this would work just like cutting them, but I would have the option of letting more slack back out if I wanted to. I'm going to drill two holes in the plastic disc close to the edge opposite the sides where the wires go and run some cord through there for the purpose of hanging the center of the dipole from a tree. I also put a drop of hot glue on the exposed ends of the elements to keep moisture from getting between the copper and the coating.

Here's some pictures I took before I pulled the wires in opposite directions and smothered them in hot glue.

https://dl.dropboxusercontent.com/u/6017319/Dipole/P1140064.JPG

https://dl.dropboxusercontent.com/u/6017319/Dipole/P1140060.JPG

222DBFL
01-14-2015, 08:23 AM
Dipole doesn't need an earth ground. What I have found is that a choke or matching balun is a good idea. If you are keeping it cheap and simple try a choke. #14awg wire will handle the power you are using fine. Also make sure to weather proof your solder connections at the so239. I used hot glue. My first one came out great and at only 15ft placed horz it kicks butt over my vert when dx is rolling in the right way. Fun stuff. Keep at it and enjoy. If ylu plan on building more antennas get an antenna analyzer, they are worth every penny and will save equipment damage! Just had a local blow 2 radios with a bad antenna, swr was only 1.3, but the ohms were at 70-75. Also had a very high X value. At any rate have fun and get that thing up as high as you can. The higher the better.

Gerowen
01-14-2015, 08:34 AM
Dipole doesn't need an earth ground. What I have found is that a choke or matching balun is a good idea. If you are keeping it cheap and simple try a choke. #14awg wire will handle the power you are using fine. Also make sure to weather proof your solder connections at the so239. I used hot glue. My first one came out great and at only 15ft placed horz it kicks butt over my vert when dx is rolling in the right way. Fun stuff. Keep at it and enjoy. If ylu plan on building more antennas get an antenna analyzer, they are worth every penny and will save equipment damage! Just had a local blow 2 radios with a bad antenna, swr was only 1.3, but the ohms were at 70-75. Also had a very high X value. At any rate have fun and get that thing up as high as you can. The higher the better.

I'm feeding it with RG8X and using the SO-239 out of an old junk radio. I pulled the elements in opposite directions and then covered the whole top of the SO-239 with hot glue to protect the connections from weather. If I'm using 50 ohm coax and copper wire with the SO-239 plug out of a CB radio, is it still possible that the copper wire itself would throw off the impedance?

I haven't talked on it for very long, just now got it constructed, and trying to figure out what in the world to hang it from outside for further testing. My porch is about 2 feet narrower than the length of the dipole, and has a metal roof. The house has metal siding and a metal roof, and there's no trees within a few hundred feet of the house.

Gerowen
01-14-2015, 08:37 AM
By the way the 14 gauge wire (the elements) is un-shielded.

Gerowen
01-14-2015, 09:24 AM
And to build a choke I would do what, wrap the last few feet of feedline in a tight coil around some PVC pipe?

SOHC
01-14-2015, 11:09 PM
I have a half wave vertical dipole I made its made from aluminum tube and hangs off the side of the house. I made the choke by warping I think 7 or 8 coils of coax with tape it has 1:1 SWR where I want it.

The ground radiator doesn't mind being close to the ground, just keep the + away from the buildings and trees.

Its not a very good DX antenna I have found.

alpha78
02-01-2016, 09:22 AM
necro thread bump! I made a dipole using solid romax electrical wiring and it worked good even though tuning it was weird given location right under and next to metal gutters. so...

my question is what difference does it make to the radiation pattern if V or inverted v as opposed to straight horizontal? would one favor local or dx over the other? how important is the angle too? I wouldn't be able to make it right angles but more shallow. also, as I'm against a hillside I don't care about rearward propagation, only forward. the sides don't even matter to me either :p pretty much unidirectional but I seriously don't think I can put up a beam. a vertical dipole on a corner of the house is a possibility but up on the second floor plenty of room for a horizontal dipole straight or v'd. having both on an a-b switch would be too cool.