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Message |
    
Cnmcake
Junior Member
Username: Cnmcake
Post Number: 10
Registered: 3-2005
| | Posted on Monday, March 28, 2005 - 12:22 pm: | 
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Just wondering if anyone has any ideas or links to instructions for building a decent antenna for CB. Base station. Im currently using a trcukers antenna for it. It would be helpful to know what kind of materials to use and etc.
Thanks you very much. |
Alsworld
Advanced Member
Username: Alsworld
Post Number: 899
Registered: 1-2002
| | Posted on Monday, March 28, 2005 - 7:10 pm: |
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Do a search here for J-Pole antennas. They look pretty easy to build from copper tubing, and past threads here have those who have made them swear it's better than an IMAX 2000.
The threads had numerous links to websites that give you exact measurements depending on what frequency you want to use it on. Also, internet searches for J-Pole work, but here you had people with first hand experience.
Alsworld |
Red_devil
Member
Username: Red_devil
Post Number: 81
Registered: 10-2004
| | Posted on Tuesday, March 29, 2005 - 9:22 am: |
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Cnmcake,
The below was Originally Posted on Saturday, February 05, 2005 - 4:53 pm:
I hope it gives you some other ideas.
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I will preface these suggestions with my situational restrictions. First, I live in military quarters and the government frowns on anyone drilling into or mounting anything on their structures. Second, you never know when you will move so ANY antenna erections must be easily removable and movable. Also, both of these ideas are removed whenever they are not in use and are never used during storms. Thus no lightning protection has been used on either option.
The first option that I will describe is for local omni directional use. I dug through my extra parts box and found an old antenna mount. I enlarged the bolt holes to make enough room to allow hose clamps to pass through. I then used the hose clams and antenna mount contraption to mount a 102” whip to the top of my kids’ swing set. OK, I’ve sacrificed antenna height but, at least it will talk well locally. Also, my SWR is a bit higher than I would prefer, at 1.9:1, but what do you want… Swing sets were not made to be used as a ground plane :-). Like I said LOW budget. Whip $16, mount $?? From parts box, swing set... victim of necessity.
The second option is even LOWER budget $5 total. This antenna is a semi-bi-directional option that I use mainly for DX purposes. I only spent money on a 20’, 12 GA spool of wire. I bet some of you are thinking dipole… You got it! What radio hack doesn’t have a few feet of coax, a wooden block, a dowel rod and a SO-239 connector in the junk box? Alright, I should have also had a few feet of 12 GA wire also. I was fresh out. Anyway, I zip stripped and hot glued the SO-239 to the bottom of the dowel, ran some RG8 mini up the side, ran the coax around the dowel six times for a choke. I then split the coax and ran it to either the leads to opposing sides of a 3 ˝” x 2 ˝” x 1” piece of wood. I used epoxy to hold the dowel to the block of wood, then screws on the 1” sides of the wood to hold the coax ends and the 12 GA wire in place. Don’t forget that all connections should be soldered. The length of the two wire radials will depend on the frequency of use and the feed should be in the center(for this antenna). Remember to make them longer that you need them for SWR trimming later. I used zip strips as my end insulators and nylon cord to hang it. I ran one end to the above-mentioned swing set (where would I be without it or a tree?)and the other to a vent pipe on the top of the house. Since the antenna hangs nicely in between the two structures at between 9’ and 7’ above the ground I end up with somewhere between a horizontal dipole and a sloper. SWR below 1.5:1. If I had a tree I would hang it vertically.
Maybe some day I will be able to buy a tower and a REAL antenna. For now, they work for me.
Any other ideas? Please share!
CEF 447
Red Devil - 392 |
Kid_vicious
Intermediate Member
Username: Kid_vicious
Post Number: 336
Registered: 9-2004
| | Posted on Tuesday, March 29, 2005 - 11:06 pm: |
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cnmcake, please describe to me what your homestead is like.
peaked roof?
big yard?
rent or own?
homeowners assoc.?
power lines overhead?
etc...
if you can give me a "picture" of where the antenna will be mounted, i can give you some ideas.
i must say, the ideas presented in red devil's post should work quite well if you cant permanently mount anything.
i hope i can help.
BTW, you need to tell me how much you can spend total on this project.
matt |
Cnmcake
Junior Member
Username: Cnmcake
Post Number: 12
Registered: 3-2005
| | Posted on Wednesday, March 30, 2005 - 11:35 am: |
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First off I own my home and so can mount as i like. That being said I would like it to be something that can be removed later down the road as we plan on selling the house eventually. That is also a reason I dont want it to be permanent as I will want to take the equipment with me.
Best case scenario for me is mounting right on top of the TV antenna I currently use for my scanner. I dont know if this is possible though. If not then I would mount it a bit down from me tv antenna. What im trying to get away with here is having both antennas mounted to the same pole. I would have already mounted it to the tv pole but the antena mount on the antenna I have wont fit around the pole. Any ideas on doing something to modify the mount on the truckers antenna so it will fit around that pole. Thanks. |
Chad
Intermediate Member
Username: Chad
Post Number: 229
Registered: 11-2004
| | Posted on Wednesday, March 30, 2005 - 7:34 pm: |
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You can stick an Imax2000 to almost anything 
Before that I used a dipole in the trees, it's still there as a backup and it is a solid performer.
I love my Imax and I bet you could rig it to your present tower, just be creative... and safe!
Chad |
Kid_vicious
Intermediate Member
Username: Kid_vicious
Post Number: 342
Registered: 9-2004
| | Posted on Wednesday, March 30, 2005 - 8:21 pm: |
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i think you're in luck, im guessing that the pole your TV antenna is mounted on is 1 1/4" in diameter.
slide the antenna down from the top of the mast so that there's about 3" of pole sticking out the top. buy a mount from rad shak called a "mirror mount". it looks like a piece of aluminum angle iron with four bolts that attatch to a plate with a groove in it. it is also called a "luggage rack mount" the groove is horizontal for mounting to the luggage rack but you can turn it 90* andbolt it to the top of your TV antenna pole.
get the BIG spring and screw it into the mount. mount a 102" whip to the spring. hook the coax up, (there is an SO-239 on the underside.)
slide the TV antenna up so its right underneath the mount.
go inside and check your SWR. if its higher than 1.5 to 1 then we'll have to add some radials but it should work quite nicely. just make sure the scanner is off when you key the mic!!!
matt |
Kid_vicious
Intermediate Member
Username: Kid_vicious
Post Number: 349
Registered: 9-2004
| | Posted on Saturday, April 02, 2005 - 2:36 am: |
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a couple of things i forgot. make sure you remove the paint from the part of the mast where the cb antenna mounts, and also from the part of the mast where the TV antenna attatches to it.
we are trying to use the TV antenna as a groundplane; that's the reason for this.
you'll also need to buy some longer bolts for the mount. use 1/4" bolts. on your mast, there is one end that is tapered so it can slide into another antenna section. make sure this end is on the top as the mount for the CB antenna wont fit around the fat end of the mast.
hope it all works out for you.
matt |
Twowatt
Junior Member
Username: Twowatt
Post Number: 18
Registered: 7-2005
| | Posted on Saturday, July 09, 2005 - 4:50 pm: |
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cnmcake, go here for some great ideas.
home.att.net/~wizardoz/cbmw/antenna_fabri.html |
Kj7gs
Junior Member
Username: Kj7gs
Post Number: 29
Registered: 12-2004
| | Posted on Thursday, July 14, 2005 - 2:31 pm: |
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Cnmcake, have you thought about a half-square antenna? Cut a quarter-wave length of wire and solder it to the center of an SO-239, or even clip an alligator clip to the wire and slide it over the center connection, I've found that it holds very nicely if you get the right size alligator clip. Also makes for easy takedown. Then cut another quarter wave, and another half wave of wire, and twist/solder a "corner" together. Solder (or just tie) the other end of the half wavelength to the "shield" side of the SO-239, and that completes the antenna design. Now get two lengths of high test fishing line, loop one around the corner you've soldered and the other loops around the SO-239. Hoist both fishing lines to where the "tails" of the 1/4 wave antennas hang just above ground level (you do have a tree nearby, don't you? Standoffs screwed into the roof will also work for "halyards"). Use fishing line sinkers to weigh the "tails" down a bit, and the result is two vertical, top-fed, no-ground-plane-needed antennas, fed in phase for up to 3.8 dB gain, in a figure 8 pattern broadside to the array. It has a very low radiation angle, is nearly invisible, and can be set up and taken down in minutes and rolled up for extreme portability. My 15m version got me contacts into Yambe Island (east side of Africa) and Svalbard Island w/o amp. Give it a try, it's a minimal investment with a lot of potential. |
Dx431
Senior Member
Username: Dx431
Post Number: 1076
Registered: 2-2002
| | Posted on Thursday, July 14, 2005 - 6:28 pm: |
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Run a Google Search for:
Ultimate Guide To 11 Meter CB Antennas
Alot of info there.
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