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Old 08-07-2012, 08:24 PM
LittleSavage LittleSavage is offline
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Default Guidance Needed - CB base station antenna



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SB,

I am in the final stages of setting up a home CB base station. I've got:

1. The power supply
2. The CB and a backup
3. Cables, cords
4. ...misc items

The only thing I'm really missing...the antenna. I know: the heartbeat of the setup and it's the last thing I add, I get it. I've got some concerns which is the reason for my delay. Since we're here because we prep, I'm slightly concerned about having an antenna on the side of my house. There are no HOA issues, but we do live in a nice residential neighborhood with plenty of eyes. I have reviewed the "stealthy" antenna below but am concerned it may not work as well as posted. What recommendations do you have? If I had my choice, I would install a similar unit in my attic, but want to make sure I have enough of a ground so I don't fry my equipment.

HELP!

http://www.hamuniverse.com/cbstrongtie.html
Old 08-07-2012, 09:26 PM
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Here's a homebrew antenna by CrypticCricket. Not as stealthy as the one in your link.


But not as obvious as this one.
http://www.hy-gain.com/Product.php?productid=SPT-500

Back in the heyday of CB, this was the bad boy of base antennas.
(I wouldn't pay much attention to the "illegal for 11 meter use" in the ad. It may be illegal to sell as an 11 meter antenna, but not illegal to use as an 11 meter antenna. Be careful around power lines. Its all aluminum.)
Old 08-07-2012, 09:27 PM
Tevin Tevin is offline
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Quote:
Originally Posted by LittleSavage View Post
I have reviewed the "stealthy" antenna below but am concerned it may not work as well as posted. What recommendations do you have? If I had my choice, I would install a similar unit in my attic, but want to make sure I have enough of a ground so I don't fry my equipment.
The antenna in your link is a basic dipole. I have a similar setup for 20 and 40 meters that I made to be portable for my ham gear. Many hams have these; they're not stellar but they are reliable, simple, and solid.

The plate he made to mount the two elements on is clever, but he did not have to go through all that drilling and bending. Ready-made mobile dipole mounts complete with threaded fittings are available for about $12 at most ham radio shops or on line. So unless you're big into metalworking, just spend the twelve bucks and be done with it.

Locating the antenna in the attic is ok; there will be a tradeoff of performance on both transmit and receive. CB maximum output is only four watts so you can't afford to waste any. If you can mount your antenna horizontally (which is the way dipoles work best anyway) under an eve or in a tree outside, you will get increased performance without too much visibility.

By the way, when dipoles are mounted horizontally the signal will favor the face sides of the antenna. For example, a dipole that runs north and south will concentrate the signal east and west. Installing it vertically (as in the link) does somewhat mess with the purpose of the antenna. I would not mount a dipole vertically unless there was truly no other option. The negative effect is less pronounced on CB since most of the comms are local/ground wave anyway.
Old 08-07-2012, 09:52 PM
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Guys...I appreciate both of you posting. I am very new to the hobby (think GREEN) and really just want something where I can listen to the bands in the event of an emergency and to get local communications. At face value, I think the covert dipole may be a good option and since the house is fairly long, I could run the antenna horizontally inside the attic.

If I went this route...should I get something like a FireStick or just run long sections of coax cable and then drop it down to my radio?
Old 08-07-2012, 10:21 PM
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Quote:
Originally Posted by low_n_slow View Post
Here's a homebrew antenna by CrypticCricket. Not as stealthy as the one in your link.

CB Radio DIY Antenna - YouTube

But not as obvious as this one.
http://www.hy-gain.com/Product.php?productid=SPT-500

Back in the heyday of CB, this was the bad boy of base antennas.
(I wouldn't pay much attention to the "illegal for 11 meter use" in the ad. It may be illegal to sell as an 11 meter antenna, but not illegal to use as an 11 meter antenna. Be careful around power lines. Its all aluminum.)
Hell, I don't see why it would be illegal to sell as an 11m/cb antenna either, unless it includes an amp.
Old 08-07-2012, 10:24 PM
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Quote:
Originally Posted by Tevin View Post
Locating the antenna in the attic is ok; there will be a tradeoff of performance on both transmit and receive. CB maximum output is only four watts so you can't afford to waste any. If you can mount your antenna horizontally (which is the way dipoles work best anyway) under an eve or in a tree outside, you will get increased performance without too much visibility.
The power issue is also a good reason to consider your coax choice, and length, carefully. Don't wanna lose the precious few watts all in the feed line.

As for horizontal mounting, would that not change the polarization and thus affect recpetion/xmit? Most CB installs out there (mobile) are gonna be vertically polarized, and I'd suspect most base installations are as well for the same reason.

Edit: doh, your last paragraph touched on that
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Old 08-07-2012, 10:45 PM
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Quote:
Originally Posted by LittleSavage View Post
Guys...I appreciate both of you posting. I am very new to the hobby (think GREEN) and really just want something where I can listen to the bands in the event of an emergency and to get local communications. At face value, I think the covert dipole may be a good option and since the house is fairly long, I could run the antenna horizontally inside the attic.

If I went this route...should I get something like a FireStick or just run long sections of coax cable and then drop it down to my radio?
FWIW I've heard of people mounting base station antennas in trees. You can also paint them to camouflage them even more.
http://cbradiomagazine.com/Articles/...%20antenna.htm

http://cbradiomagazine.com/CB_Articles.html#Antenna
Old 08-07-2012, 10:53 PM
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Quote:
Originally Posted by low_n_slow View Post
Here's a homebrew antenna by CrypticCricket. Not as stealthy as the one in your link.

CB Radio DIY Antenna - YouTube

But not as obvious as this one.
http://www.hy-gain.com/Product.php?productid=SPT-500

Back in the heyday of CB, this was the bad boy of base antennas.
(I wouldn't pay much attention to the "illegal for 11 meter use" in the ad. It may be illegal to sell as an 11 meter antenna, but not illegal to use as an 11 meter antenna. Be careful around power lines. Its all aluminum.)
That doesn't make sense at all. How can an antenna be illegal to sell or use for CB? The only restrictions I know of are the height restrictions.
The FCC did propose a rule (never passed) on certain types of antennas for CBs but nothing on omnidirectional antennas.
Old 08-08-2012, 04:53 AM
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I once built a base antenna using a 102" whip, 6" coil spring and a mirror mount bracket (the kind that bolts to a mirror arm.) I used 9 foot wires attached to the bracket to act as my ground plane.

I attached it to a gable on my house, and although it did stick up over the roofline, it wasn't that noticable. You would have to look hard to see it.
Old 08-08-2012, 05:13 AM
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I'm making a new video about that 102" whip- base station antenna in the video above. I talk more about parts and dimensions and putting it together. It's an awesome antenna. It's performing almost as good as the 5/8 wave verticals near me. It's got excellent "ears" and once in a while it accidentally skips with conditions. I painted it with brown camo paint and so long as you have trees as a background, you can't spot it even when looking right at it. Even without paint, it didn't catch your attention.
Old 08-08-2012, 06:30 AM
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Go with a vertical antenna, all the local mobiles will be vertical anyway (signal polarity).
They have a smaller footprint (less obnoxious) visibly for the neighbors.
A vertical doesn't require a rotor for TX/RX in different directions, but there is a trade off in DB gain.

I have a Sirio GPE-27, and find it to be an excellent antenna.
Old 08-08-2012, 03:54 PM
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I just uploaded my video about my 102" whip, vertical ground plane antenna.

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Old 08-08-2012, 03:59 PM
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Quote:
Originally Posted by dtom1911 View Post
That doesn't make sense at all. How can an antenna be illegal to sell or use for CB? The only restrictions I know of are the height restrictions.
The FCC did propose a rule (never passed) on certain types of antennas for CBs but nothing on omnidirectional antennas.
There is a current proposal on file that includes a modification to ban certain types of directional CB antennas and I think there is even a proposal to lift the distance limitation too. As of right now, there are rules that limit the height of a CB antenna to not more than 20 feet above the structure it is mounted on. So that basically and technically bans the Imax 2000 at 21 feet and some of the older antennas that were .64wl at I think about 24 feet.

I would guess that since the FCC has been known to crack down on places selling illegal CB stuff that they have to put the disclaimer on the site. technically any antenna for CB over 20 feet tall from the feedpoint or mounting bracket is illegal, so they have to cover their @ss.

Quote:
Originally Posted by FCC Website
For structures, the highest point of your antenna must not be more than 20 feet above the highest point of the building or tree on which it is mounted, or 60 feet above the ground.
http://ecfr.gpoaccess.gov/cgi/t/text....1.1.5.4.144.8

I wouldn't put too much stock in the antenna size rule. Its common knowledge that the 5/8wl antennas were commonly used back in the days when the FCC did enforce the rules and I have never heard of anyone getting busted for having a 22 foot tall antenna. But it is technically illegal so YMMV.

EDIT: As to the reasoning behind the 20 fot rule for CB antennas, I have never seen any technical documentation as to why the FCC would put that limit, but 20 feet is plenty of length to include a 1/2wl radiator, matching network in the base of the antenna and a sturdy mounting surface and still have about 6 inches to spare.
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Old 08-08-2012, 06:07 PM
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Quote:
Originally Posted by KF4LNE View Post
There is a current proposal on file that includes a modification to ban certain types of directional CB antennas and I think there is even a proposal to lift the distance limitation too. As of right now, there are rules that limit the height of a CB antenna to not more than 20 feet above the structure it is mounted on. So that basically and technically bans the Imax 2000 at 21 feet and some of the older antennas that were .64wl at I think about 24 feet.
To add to KF4LNE's excellent insight, the "20 foot rule" is kind of lame because the low power output of CBs limits how high an antenna can realistically be anyway. The "problem," if there even is one, more or less takes care of itself.

To put it in newb terms, having your CB antenna atop a 70 foot tower sounds real cool but by time you push that peanut whistle signal up all that coax there won't be much of a signal left to radiate. Likewise on receive.

Using the Bury-Flex mentioned in the original post's link, 4 watts becomes 3.38 watts at 100 feet, and that's assuming 1:1 SWR. That's actually not too bad. Bury-Flex is good stuff. The average CB-er is not too picky and is going to use whatever cheap lossy crap they can find on sale. Add in poorly terminated connectors and a few adapters along the way and the wattage just keeps draining out. Yes, coax counts! Big time!
Old 08-08-2012, 08:07 PM
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Quote:
Originally Posted by Tevin View Post
The average CB-er is not too picky and is going to use whatever cheap lossy crap they can find on sale. Add in poorly terminated connectors and a few adapters along the way and the wattage just keeps draining out. Yes, coax counts! Big time!
Have you seen the crap they sell at CB shops? They often sell some kind of crap mini-8 with some kind of plastic and pot metal $.99/ea hamfest special connectors on it and frequently the shield hasn't been soldered. And it comes in 72 foot lengths because its 2 wavelengths long or some snake oil like that.
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Old 08-09-2012, 03:40 PM
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Quote:
Originally Posted by thoreau View Post
Hell, I don't see why it would be illegal to sell as an 11m/cb antenna either, unless it includes an amp.
It has to do with the materials the antenna is made from. For some dumb reason, CBers can't be trusted with all metal antennas around power lines. CB antennas are now required to be made of non-conductive materials (fiberglass) and/or have some sort of mechanism to keep the end user from being electrocuted in the event the antenna contacts power lines.

I have my ham ticket and I think this is pure nonsense. Its OK for a ham to have an all metal antenna, but not the CB community?! I don't think that piece of paper hanging on the wall will provide much insulation if I drop an antenna across a power line.
Old 08-09-2012, 11:24 PM
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Quote:
Originally Posted by KF4LNE View Post
There is a current proposal on file that includes a modification to ban certain types of directional CB antennas and I think there is even a proposal to lift the distance limitation too. As of right now, there are rules that limit the height of a CB antenna to not more than 20 feet above the structure it is mounted on. So that basically and technically bans the Imax 2000 at 21 feet and some of the older antennas that were .64wl at I think about 24 feet.

I would guess that since the FCC has been known to crack down on places selling illegal CB stuff that they have to put the disclaimer on the site. technically any antenna for CB over 20 feet tall from the feedpoint or mounting bracket is illegal, so they have to cover their @ss.


http://ecfr.gpoaccess.gov/cgi/t/text....1.1.5.4.144.8

I wouldn't put too much stock in the antenna size rule. Its common knowledge that the 5/8wl antennas were commonly used back in the days when the FCC did enforce the rules and I have never heard of anyone getting busted for having a 22 foot tall antenna. But it is technically illegal so YMMV.

EDIT: As to the reasoning behind the 20 fot rule for CB antennas, I have never seen any technical documentation as to why the FCC would put that limit, but 20 feet is plenty of length to include a 1/2wl radiator, matching network in the base of the antenna and a sturdy mounting surface and still have about 6 inches to spare.
I read the rules before and swear I thought it meant the base of the antenna. Oh well. My antenna is staying wear it's at for now.
Old 08-10-2012, 12:00 PM
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Quote:
Originally Posted by dtom1911 View Post
I read the rules before and swear I thought it meant the base of the antenna. Oh well. My antenna is staying wear it's at for now.
Legally, and if you have permission from KVLY, you can put your antenna on the KVLY-TV Tower as long as the antenna itself is no more than 20 feet above the top of the structure it is mounted on. I'm not sure where you're going to find coax that can carry a 4 watt signal for a half mile strait up and still have any signal to radiate though.


Also, this bit of the wiki article can go to show how even at 2000+ feet above the flat ground in Eastern North Dakota, with a transmitter putting out over a quarter million watts ERP, the range still sucks.

Quote:
Originally Posted by KVLY-TV Wiki Article
The tower is located 3 miles (4.8 km) west of Blanchard, North Dakota, halfway between Fargo and Grand Forks. It became the tallest artificial structure, and the first man-made structure to exceed 2,000 feet (610 m) in height, upon the completion of its construction on August 13, 1963.
The tower was built by Hamilton Erection Company of York, South Carolina and Kline Iron and Steel, and took thirty days to complete, at a cost of US$500,000.
Owned by Hoak Media of Dallas, Texas, the tower broadcasts at 356 kW for television station KVLY-TV (channel 11 PSIP, an NBC affiliate) which is based in Fargo. The tower provides a broadcast area of roughly 9,700 sq mi (25,000 km2) which is a radius of about 55.6 miles (89.5 km).
Old 08-11-2012, 12:32 AM
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Quote:
Originally Posted by KF4LNE View Post
Legally, and if you have permission from KVLY, you can put your antenna on the KVLY-TV Tower as long as the antenna itself is no more than 20 feet above the top of the structure it is mounted on. I'm not sure where you're going to find coax that can carry a 4 watt signal for a half mile strait up and still have any signal to radiate though.


Also, this bit of the wiki article can go to show how even at 2000+ feet above the flat ground in Eastern North Dakota, with a transmitter putting out over a quarter million watts ERP, the range still sucks.
I believe mine would still fall within specs anyways. The base of the antena is at or about the peak of the roof and the antena is 18' long. I have hard enough problems with heights just getting up on the roof. No way am I ever climbing something that tall!
Old 08-13-2012, 02:47 AM
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You can think about hiding the antenna in plain sight. A painted antenna is difficult to see from the street if you paint it a neutral color. Or you could put up a flag pole, lots of hams use "flagpoles" for an antenna in HOA areas.

Vertical would be best, most (not all) people with base stations run horizontally polarized antennas but mobiles are going to run verticals.
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