CB Antenna

[mdmead]

This is actually a project on my Bronco, but we'll pretend it is for my Safari!

Anybody have any good advice on picking a new CB antenna. I've got a short fiberglass whip that performs poorly. I started looking at other options online and decided before I pick something, I'd see what others have to say.....

[GnarliSafari]

i bought a splitter and have my cb run through the stock radio antenna. works better than any of the other antennas ive had.

[Bubbathegimp]

since the body of the vehicle (bumper mount) would block the majority of the antenna affecting signal and cause swr issues, I mounted a ball mount in the center of my roof (ground plane effect) and used a 5/8 wave fire stick on my stro-fari.

no biggie since the headliner was already down. I just ran the coax between the roof braces over to and under the plastic window trim.
Then ran the coax underneath the dash using pull ties over to the radio mounted to the hump.

if you want to re-enforce the roof it isn't much effort to use the grommet for a template to make a brace, or you might find that a small circular saw blade with the right sized center hole could be used in a pinch on ball mounts with the SO-239 connector.

I think that the type of ball mount with the connection directly to them instead of using the SO-239 may be the better way to go. I tried using a angle connector with the so-239 type and discovered that it added a 10th of a point to the swr....

Also, a better grade of coax can also be used such as LMR-240uf. better shielded than your typical RG-58 ,mini-8 etc to help with ignition noise AND has lower loss......

BTW radio shack, even though it isn't the best place in the world as far as radio goes (cellphoneshack) has as far as I know the better made heavy duty spring coils.

[NotDadsW41]

Get a Wilson 5000 and mount it in the roof of the Astro. You won't regret it.

[LiftedAWDAstro]

I bought a couple of Firestick II FS series 5 footer for the SPB and a standard 4 or 5 foot Firestick II for Lynnes Jeep.

Here you can see where I mounted it on the SPB. It worked great in the forward direction but not very well in the rearward direction. Range was decent but not great.



Here you can see in the back left corner where I mounted the antenna on the Jeep. This was a convenient place to mount it but the range was very limited.



Mounted in the center of a large flat piece of steel is the best place.

[rlsllc]

I agree with Bubba, but did wimp out and use a magnetic mount.

I am in no way an expert, and am only sharing my one experience at a CB shop. This was on my F-350 service truck that I used to have, not my Astro. Mounting top and center is the only way to go for maximum range. Has something to do with ground plane.

I used a Wison, but can't remember the number, and bought a long whip and trimmed it down to the best SWR for my ride. There was something about how much to cut, but I don't remember the amount.

Coax length is as important as the type, which is very important. The shop I used said that length should be adjusted in 3' sections, and to have extra connectors to solder on and check the SWR after shortening. Had something to do with sine wave, and the velocity of propagation of the signal through the cable according to the shop guy. He said to take off 30", term and test, and if it dropped SWR, trim it down and reterm until you get the best (or at least what you had before cutting) SWR. I got lucky and matched on the first connector (I cut off 35") and only had to do it once. I cut it so I could feed the cable through a small hole, and I mounted the radio above where the winshield rear view mirror should be.

I was sceptical of all trimming, etc, but can say that this rig really got out there, and I could pick up truckers several milemarkers ahead of and behind me. If I could hear them, I could talk back. Usually that's a good sign.

I was just using a stock Cobra 29 NW CB.

[Bubbathegimp]

I agree with Bubba, but did wimp out and use a magnetic mount.

Nothing wrong with using a Well Made magnet mount on HF (11 meters) as long as you are using legal power. It's when you start using Illegal power that you start having problems such as "RF Feedback" etc.

Mounting top and center is the only way to go for maximum range. Has something to do with ground plane.

BINGO! if you mount your antenna lower, not only do you have to contend with movement constantly changing the SWR when you travel, But the body of the vehicle will block a portion of the signal and the signal path will be towards the direction of the most metal.

Say your driving grandmas pinto wagon (god forbid) and you have that big ole 102" steel whip mounted to the drivers side rear bumper.

1. not only is about 1/4 of the "radiator" blocked
2 your best signal is going to be in the direction of the front passenger side.

To illustrate, I knew a guy in kentucky with a FULL size van and steel whip mounted on the rear bumper (including tennis ball).
At the time I had a 80 Bonneville with a K40 on the trunk. Sitting next to him in a parking lot I was able to demonstrate how easily I could talk all over him with my puny antenna versus his big old steel whip.

I used a Wilson, but can't remember the number, and bought a long whip and trimmed it down to the best SWR for my ride. There was something about how much to cut, but I don't remember the amount.

Wilson has some fine antennas. I like the Wilson 1000 a lot better than the K40. If you get a chance to compare the two look at how they are attached to their mounts and you will see why I prefer the Wilson. I have never used a wilson 5000 BUT a "million" truckers cant be wrong

Coax length is as important as the type, which is very important. The shop I used said that length should be adjusted in 3' sections, and to have extra connectors to solder on and check the SWR after shortening. Had something to do with sine wave, and the velocity of propagation of the signal through the cable according to the shop guy. He said to take off 30", term and test, and if it dropped SWR, trim it down and reterm until you get the best (or at least what you had before cutting) SWR. I got lucky and matched on the first connector (I cut off 35") and only had to do it once. I cut it so I could feed the cable through a small hole, and I mounted the radio above where the winshield rear view mirror should be.

A common myth that has been around for years. If your SWR is changing by changing the length of the coax then there is something wrong at the antenna (shorted out etc). what you are actually doing is tuning the coax itself and turning IT into the "antenna" The best length of coax for a PROPERLY working antenna system is only what you need to make it from the antenna to the radio and a little extra for necessity.

took a quick look and found this for you

http://www.stu-offroad.com/misc/myth-1.htm

I was just using a stock Cobra 29 NW CB.

Cobra 29's have been very popular radios for a long time. Glad to hear that you havn't had it "peaked" into a splatterbox

[mdmead]

Wow, a lot of good info here! And thanks Bubba for your research too! (The link was very interesting reading.)

OK, so it seems one of the most important things is getting the antenna topside. It just so happens I have a big ol' steel roof rack that I can mount to!

[Bubbathegimp]

Wow, a lot of good info here! And thanks Bubba for your research too! (The link was very interesting reading.)

OK, so it seems one of the most important things is getting the antenna topside. It just so happens I have a big ol' steel roof rack that I can mount to!

That will work you might want to try drilling a small hole through a mirror mount and the roof rack and installing a small screw to keep from swiveling the mount though......