Sinking Creek 4WD Association

OK guys, since I probably did as much harm as good tonite, I figured I'd post up some information to help. These are my sources and some good reading assuming you have the time and want to learn a quick thing to help you get out. If one of the mod's wanna stickey this and keep the info at hand, I'll try to keep it updated when I find new information/sources.

1st: Nick, here's the GROUND PLANELESS 48" ANTENNA .

2nd: Mother of all antennas, 102" S/S whip. You DO have to run a spring or 6" spacer with these to get the correct electrical "length".

3rd: Good Antenna/Coax Information for Base/Mobile Setups

4: 108" whip. You do NOT have to run a spring with this to get the correct length.



Some Quick Tips

SWR: Standing Wave Ratio. This is the measure of antenna efficiency.

Make sure all ground connections are made to BARE metal. I sand to the bare metal, mount my ground cables then use touch up paint from Advance Auto to seal the connections and keep them from corroding.

Do everything you can to use an antenna mount that bolts to the body. Improved grounding will help with noise and transmitting. Also, SWR should be checked at the antenna end preferable.

The antenna is the MOST important part of the system, buy a good one.
Make sure if you use a fiberglass whip (FireStick, Wilson 1000, ect) that it has the tunable tip. If not, you just shot yourself in the foot.

Mag-mounted antennas are decent, but not great as they do not have a ground plane. They will limit your ability to transmit and can cause excessive SWR readings.

The little RF noise filters you buy at Walmart and most parts stores for car stereos work great for taking noise out of the DC feed for the CB.

To check where the excess noise is entering the CB: With the motor running, un-hook the coax from the back of the CB. If the noise goes away, then it is entering through your antenna system. I'm still trying to cure mine, I believe its in the spark plug wires as of now. If its coming in the DC line, add the little RF filter mentioned above.

Myths about CBs

I'll add more to this as I find them.

1: You HAVE to use 18' of coax to make a cb have a good swr.
Horse hockey.... 18' is the length of 1/2 wave of the cb band in a vacuum. Somewhere along the way somebody decided that if your antenna has to be a 1/2 wave, your coax should too. NOPE. In coax, you have to take the length of the half wave and multiply by the efficiency of you coax (between .66 and .80 depending on brand, type, age, ect). So, in actuality, ~11.88-14.4' of coax is the correct length for a 1/2 wave. The proper length of coax is the length between your radio and your antenna by way of how you route it. The exception to this is Mag-Mounts. The coax is a certain length because of how they capacitivly couple to the body to establish a ground plane.

2. Coiling your extra CB coax will hurt your SWR.
NOPE, it can actually help keep interference down if done properly. For RG-58 (standard cable with 99% of mobile antennas) make 6 ~6" diam coils and tape them together to help remove unwanted noise.

Quick opinion question: Which would likely be the best bet on my Suburban: 102" whip on one corner of my back bumper or a Wilson 1000 on the roof?

I've got both antennas, but I'm not likely to actually go through the trouble of installing the 1000 through my roof if the whip will work as well or better on the bumper.

Mounting it on the bumper is not going to be good on a Suburban. You'll be firing the majority of your power into the body, creating high SWR's. What you want to do is go up about 3/4's of the way on the body, and use a ball mount with a shock spring and the 102".

This will allow the antenna to flex backwards and the ball mounts are pretty strong. You can make a steel plate to go on the inside of where you mount the ball mount to help strenghten the body and keep it from flexing and cracking. Unless you have a pickup, the 102" on the bumper is a bad idea, and even with a pickup, its still not the best idea.

The information you gave says you have to run a spring with the 102" whip to make it the correct electrical length. I am looking at a 5' Firestik...but i also need to fit into the garage, so i was going to use a fold over..... along with a spring (in case the antenna hits anything on the trail.) My question is...will this setup make the antenna impossible to tune correctly because the electrical length will be too long.

It shouldn't due to the fact that the tuning tip on a firestick is made to take up for a spring and different types of mounts. Wilson makes a fiberglass antenna in 3' and 4' lenghts that they claim will bend 180* without breaking. You might consider it.

http://www.wilsonantenna.com/fg.htm#flex

Terry:

I am looking for/pricing stuff for a cb. It looks like the 102" would be best for reception etc., but mounting it on the hood/top of vehicle would make it too tall. Do you have any suggestions? Could I mount on bumper? or would I be better off getting a shorter antennae and mounting on hood area?

Brett

Sorry Brett, been busy and forgot to reply, here goes:

Hood mounting will be the best thing for you. As far as antenna type, I'm afraid you're stuck with fiberglass. A 3' or 4' with a spring stout enough to control it, but one that will still flex w/o bending the mount. I'm not sure where you can find a mount, I know they make them for Fords though, as I've seen a few around town before.

If you wanted to run a 102", you could and it would work ok, but mounting would be an issue. The lower you mount it, the worse your SWR's will be. Ideally, mounting on the side of the truck with a ball mount would work best, close to the top of the metal part of the body just below were the topper lifts off. If you mounted it on the bumper, SWR's would suffer greatly, and depending on the CB you use, so could your ablility to use it. Eric and I both have the problem of high SWR's causing our CB's to stop recieving occasionally.

Stay away from Mag Mounts for off-roading. They just come off too easily. The last thing you need is a $50-$80 mag mount antenna sliding off and tearing the coax off it when it goes under a tire.

No matter what way you go, remember that you can have the best CB money can buy, but if you don't have a quality antenna to go with it, you might as well be shouting!

If you are going to put this much into CB you might as well just get your HAM radio licenses. More bang for your buck and you can get more power and way farther than with a CB. It is easy to get too.

Personally I only need to talk to people on my CB that are less than 1 mile away. Which most CB's out of the box with any antenna will do. That is why I bought a CB that can be a hand held or hooked to a vehicle mounted antenna. I understand if you are always on the highway driving then yes you need everything you can get, but for wheeling all you really need is something to work with in a mile. Just my $0.02 Take it for what it is worth.

That's a prefectly valid point and Dave has run a hand held in his truck before. The reason I like a vehicle mounted one is that they work better even for that short a distance. Being in the vehicle when you use it, the metal body absorbs some of the radio waves and hurts range. When we were at Uwharrie with Dave, we were 3 rigs back and couldn't understand what he was saying. In a vehicle, the body is part of the antenna system, and when properly tuned, doesn't absorb any power, merely helps direct it. Also, my vehicle mounted Cobra 18WXSTII has 10 of the weather bands on it, so I can keep track of the weather since no radio stations have the weather on anymore.

Another reason is if you are out of cell phone service and something happens. The night Brett, Matt, Dave, Chris, Randy, Don and myself were on Potts and Brett broke. Chris took me and Don back to town early because we both had to be back. We stopped at the top of the mountain on 42 (not sure of the mountain's name) right outside town and radioed back to them to see if they needed any more help or needed us to call anyone for them. I think it was close to 8 miles between them and us.

TerryD wrote:That's a prefectly valid point and Dave has run a hand held in his truck before. The reason I like a vehicle mounted one is that they work better even for that short a distance. Being in the vehicle when you use it, the metal body absorbs some of the radio waves and hurts range. When we were at Uwharrie with Dave, we were 3 rigs back and couldn't understand what he was saying. In a vehicle, the body is part of the antenna system, and when properly tuned, doesn't absorb any power, merely helps direct it. Also, my vehicle mounted Cobra 18WXSTII has 10 of the weather bands on it, so I can keep track of the weather since no radio stations have the weather on anymore.

Another reason is if you are out of cell phone service and something happens. The night Brett, Matt, Dave, Chris, Randy, Don and myself were on Potts and Brett broke. Chris took me and Don back to town early because we both had to be back. We stopped at the top of the mountain on 42 (not sure of the mountain's name) right outside town and radioed back to them to see if they needed any more help or needed us to call anyone for them. I think it was close to 8 miles between them and us.

I think that was the last time my CB worked

Is there any interest in doing a CB "workshop" at one of the meetings? I know last year/semester everyone was broke (some in more ways than one) and I didn't have alot of time. Since I'll be at 99% of the meetings this year I thought some of you might want some help getting your CB's going.

Yes from me.

Yeah, my CB works pretty well, but I wouldn't mind having you take a look at it/tune it.

And thanks for the offer Terry.

Well, I remember alot of interest in it last year, and I did a little session, but didn't get to check many radios. Let me know when everyone will be ready and have any new equipment you want to install and I'll bring my meters and junk. Feel free to ask advice before you buy anything as well, there's no reason to buy something if it won't be optimal for your setup.