CB Radio Information and Installation

Hey yall, as a (hastily) trained former (part-time) radio operator in the U.S. Marines, I feel compelled to share my research on CB radio installs and reception.

Any of you formally trained 0621 guys feel free to put me in my place if I mess up the radio basics. And any of you graphical people can laugh at my MS Paint images.

Bear in mind this is not for an amateur radio audience, it's written for simple CB setups for normal people. If you want to point out the fact that I can't talk to Mars with these setups, or feel compelled to make a comment about HAM radios, go start another thread about it.

I have searched through the site for quite a while looking at different places people have mounted their radios and antennas. I have read a lot of posts where people are having problems with tuning, blowing their radios, or not getting good reception. I figured I would compile all the threads I found and then tell you how I did my install and maybe some radio info along the way.

Section 1: Basic Radio Concepts

Section 2: Radio Signal Propagation

Section 3: Antenna Types - The Most Important Part!

Section 4: CB Radios

Section 5: Wiring

Section 6: Mounting the CB

Section 7: Mounting the Antenna

Section 8: Antenna Tuning

Thanks to:
LUSETACO for the extra info and corrections.
Benson X for a good install thread.
CircuitBreaker for additional information.

Disclaimer: Anything you do yourself, you are always taking a chance something will go wrong. I have written my own personal experience in this thread and take no responsibility for any harm or damage caused to anyone or any property. Use common sense, if you don’t understand something, go get an expert to help.

 

Section 1: Basic Radio Concepts

If you want to know the basics of radio communication, read this section. Otherwise, skip down to Section 3.

All radios operate basically on the same principles: radio waves. A lot of the below can be applied to other types of waves, such as your Wi-Fi routers and what not.

So, a radio consists of seven parts:

• Transmitter (Sends a signal)
• Power (Makes blinky lights, etc)
• Transmission line (Delivers the signal to the antenna)
• Transmitting antenna (Sends the signal into the air (or "space"))
• Receiving antenna (Intercepts the signal)
• Propagation path (The path the radio signal follows)
• Receiver (Translates the signal into sound we can understand)

Note: For typical CB applications, the transmitting and receiving antenna are one in the same.

Radio waves are what’s being transmitted and zip around the Earth's surface and radiate upward at different angles at the speed of light.

Wavelength is the distance between the crest of one wave and the crest of the next wave (this is one "cycle"). When we refer to "frequency", we are talking about the number of complete cycles in one second. The longer the cycle, the longer the wavelength and the lower the frequency. The shorter the cycle, the shorter the wavelength and the higher the frequency.



The frequency for CB is 26.965 (CH 1) to 27.405 (CH 40). Channel 9 is reserved for emergency use and traveler assistance (although some of our local Mexican community doesn't seem to know this...)

If you want to know your wavelength in feet, check out this calculator here: http://www.csgnetwork.com/freqwavelengthcalc.html (Your antenna is probably 1/4, which means 9')

The FCC governs the use of CB in the U.S. (I don't know about Canada) . I doubt anyone will break rules with their mobile CB rig. But it should be mentioned that you cannot raise the power, or amplify your CB. It is also not legal to use HAM radios on the CB frequencies, but this is often not reported. I think penalties were something like $500.00 per day of illegal use. That could have changed, I don't know.

 

Section 2: Radio Signal Propagation

There are different kinds of ways that a wave travels (or "propagates"). In the sky and on the ground are different, but we are typically only concerned with the ground ones: Directly, reflection, and surface.

I won't go into these in detail or when you should be relying on which ones, but it's a good read if you decide to look it up.

• Directly is when a wave goes.. well.. directly to the intended receiver (line of sight).
• Reflection is when it.. well.. reflects off something and makes it to the intended receiver.
• Surface waves travel closely along the earth’s surface based on the Earths conductivity (only for so long).

Waves can also diffract off things, like in the example I drew below. Again, if you want to know more about radio wave propagation, read a good book on it. It will give you a new perception on signal strength, satellites, and radio.

When determining if you will be able to talk to your buddy, keep these three paths in mind. For example, if there are a bunch of trees and rocks between you and him, your radios might still communicate due to surface waves or due to reflection off a solid distant object.

However, the signal will start to weaken, the more it has to bounce around or travel.

Remember: the position of your antenna in the current terrain is key!

 

Section 3: Antenna Types - The Most Important Part!

Always remember this: signal strength relies on your antenna and terrain. Not the radio itself! That $30 radio will have the same signal strength as a $300 radio if they both have the same antenna and terrain. Never get an expensive radio and a cheap antenna, you will cry.

Most CB radios use omnidirectional antennas, meaning they send signals in 360 degrees outward from all sides of the antenna (however, not typically straight down or up). For this reason, it is important that you have as much of the antenna above the top of your truck cab as possible.

Having the antenna on the roof is great (it gives you a large ground plane), but isn't always the best place if you plan on wheeling or driving somewhere that would cause it to strike something. 3/4 of the antenna above the roof of the cab would produce great strength, and is how I am using mine. Having half the antenna above the truck is typically acceptable and you may not notice weak signals if you are just talking with a group close by.

Just put the antenna where you like it and allows you to send a good signal for what you need. I am not going to get into placement as it relates to signal strength since there are so many variables to it and everyone's truck is configured differently. If it's not sending a good enough signal, you may need to move it around. If you want to learn more about getting maximum distance and lowest SWR readings out of your antenna, you need to research ground planes, antenna coils, and placement a lot more. For simple application of short range CB, this is unnecessary.

For typical wheeling trips, I wouldn't imagine you need a lot of strength. So put it somewhere that you like it and won’t cause any obstruction while driving. Below are links to posts regarding locations, there are probably more (use search):
www.tacomaworld.com/.../bamf-2nd-gen-tailgate-cb-antenna-mount
www.tacomaworld.com/.../simple-cb-antenna-mount

Also related to placement is the length of the antenna. Longer antennas work better than shorter ones. Anyone who tries to convince you otherwise because of "coil load" or "Fu#k!ng MAGnets!" or whatever is trying to sell you something that isn’t actually that great (probably).

I'm not getting into coil loads on antennas, just know that where the coil load is on the antenna is where the strongest signal will be coming from. Higher is typically better, but the lower you go, the more watts it can take and easier it is to manage (because they are usually shorter). If you can get the coil of the antenna above the roof of the cab, you're probably in good shape.

Antenna grounding is VERY important. If you do not ground your antenna, expect serious problems. As in, permanent damage type problems. Always, and I mean *always* ground your antenna (unless it's an NGP antenna, see below). A good ground will also solve some of your tuning frustrations (covered later).

Note: No-Ground-Plane (NGP) antennas are out there and don't require grounding. But they are not nearly as strong as a grounded antenna and usually require an adapter of sorts, and specialized cable. Again, if you’re not sending signals far, a NGP antenna might be for you. But I don't recommend it for a truck application. NGP setups are typically better for watercraft.

Here is some information about NGP antennas:
http://www.firestik.com/Tech_Docs/ngp-critical.htm
http://www.firestik.com/Tech_Docs/NGP_Install.htm

 

Section 4: CB Radios

Seriously yall, the radio doesn't matter much in terms of signal and strength. Where it matters is in features. How many do you want, and do they seem to help make life convenient.

The exception is if you are looking at a handheld CB radio. You may want to consider a mounted one instead. Not that there aren't great handhelds out there, it's just that you wont get the same performance for the price. Handhelds might be great for talking in very, very short range situations, but they will not have great performance. If you are dead set on a handheld, check this one: http://www.walmart.com/ip/Midland-Miniature-Handheld-CB-Weather-Radio/10603644. Its a Midland 75-822 Handheld CB Radio that can be attached to an external antenna and powered from the cig lighter.

Back to mounted CB radios, there are also types that have a PA (loud speaker) built in. This requires additional installation that I am not covering here, but gives you the option of yelling at crazy drivers or scaring your dog without having to roll the window down.

All the major brands of CB radios have good warranties in place. Check to make sure your's does. Typically, they will cover the radio unless you fried it by hooking it up wrong or running it with high SWR (covered later).

Here is how I chose: what is the smallest one that is a name brand and fits in my mount spot. My answer was Cobra 75WXST, yours may be different, but the concepts here are the same. Here are a couple of links to some good CB packages that include everything you need for a good CB install:

www.rightchannelradios.com/uniden-jeep-off-road-cb-kit
www.rightchannelradios.com/cobra-75-jeep-off-road-kit

Feel free to take this list and go find your own deals, I just posted these for parts reference.

You will need at a minimum:

• CB Radio
• CB Antenna and Mount
• SWR Meter (or borrow someone's)
• Coax Cable

Depending on how you install your rig, you may need to invest in some other equipment like an antenna spring or disconnect, a noise filter (hopefully not), or a PA speaker (external horn so everyone can hear you).

One thing to be careful of though: a lot of radios are now manufactured in China and can be hit and miss in quality. Cobra did this and I am sure they are seeing many more returned radios because of it. The first Cobra I got was not functional, but the second one has been working for a long time. Just do a function check before you mount everything in place permanently.

 

Section 5: Wiring

Your probably thinking "Jesus monkey-wrenching Christ when are we gonna do something here!?". Well, here is how I did my wiring:

First, if you aren't an electrician (I’m not either) you should get a basic understanding of how it all works. Here is a great thread on the subject:
www.tacomaworld.com/.../electronics-basics-reference

Also, if you’re not sure what gauge wire to use, check this table (I used 12 because that’s what I have around):
http://www.rbeelectronics.com/wtable.htm
Remember, you can always go larger, but never smaller than the load your device is pulling. That could cause a fire.

When wiring power, wire the radio directly to your battery and use the fuse that came with the radio. "But I wanna use a fancy-pants fuse box!!" - Unless you plan on using some serious shielding and possibly paying the extra for a noise filter, it’s not worth it. It's too easy to just run wires to the battery and not have a lot of interference noise problems. If you can hear the engine or radio static in the CB output, you may have to move power cables around. This kind of interference can be hard to troubleshoot, but I have not had this problem since I started using RG8X cable for power.

To turn a coax into a power cable, first I cut the PL-259 connectors off. Then, I stripped the wire to expose the wire webbing. This webbing will be your negative, so unravel it and twist it up into a wire type shape. Next, strip the center coax wire. The center wire will be the positive.



I ran the power cable through the firewall and hooked it up to a switch that will give me a bright blue down-facing light. This will give me the option of switching it on and off while keeping the same volume setting and provides a nice reminder that it does have power. I doubt the CB will run down your battery overnight, but I wouldn’t take chances.

 

Section 6: Mounting the CB

Where you mount your CB is not going to matter unless you don’t have the cable length to get you there. Here are a few threads that show different styles:
www.tacomaworld.com/.../hidden-cb-install-pics
www.tacomaworld.com/.../cobra-29...center-console
www.tacomaworld.com/.../storage-bin
www.tacomaworld.com/.../cb-radio-antenna-mounts
You can also search and find many more.

Note: It's best to pick a 9' or 18' cable length. 18' will be plenty to allow almost any mounting location on our trucks. There is some debate on wavelength in relation to cable length, but for a simple mobile CB application, don't worry about it. 18' and 9' are the typical lengths the cable is sold in.

For mine, I mounted it on the bottom of the seat. All the controls are in the handset, so I don’t need the connector box to be accessible unless I need to re-tune the antenna. I had to drill another hole in the seat to fit the connector box.

 

Section 7: Mounting the Antenna

I already covered the locations and such in Section 3, so I’m not going to repeat. But I will cover some mount plates.

Typically, a 3’ whip antenna won’t need super heavy duty mount hardware. But if it’s a stiff fiberglass one that is always whacking limbs, it might. Just try to use your best judgment on antenna length, thickness, flexibility and location to determine how heavy duty your mount hardware should be.

There are also some neat accessories that will help with antenna management. There is a fold down piece that allows you to fold down the antenna in a direction when you aren’t using it, or going under something big. There are also detachment pieces that let you remove it altogether.

Note: You may want to tune it before tightening up the antenna and routing the coax through the truck. You never know if you are going to have to move it or not. With it mounted on the tailgate, roof, or hood, it shouldn't be a problem. Better safe than sorry.

Since I don’t mount on the roof or hood, and I am using a 4’ very flexible whip. I will not be using any attachments, but it’s your preference. Remember sometimes attachments can affect your tuning (covered next).

Because it’s sturdier than some of the other tailgate mounts I have looked at, I used this one:
www.tacomaworld.com/.../bamf-2nd-gen-tailgate-cb-antenna-mount
This does not come with the antenna mounting bolt, so you will need to buy that also.

Note: When mounting this one, be very careful with the factory bolts. They will strip out rather easy.




There are a few types of coax you can use, but they all should use the PL-259 connector. Buy a high quality cable since these are not regulated and sometimes are manufactured poorly. On the lower end, you can go with RG58, but may get some feedback issues. On the high end, there is RG-59, but it that may not be necessary unless your running dual antennas or have terrible feedback issues. The one I recommend is RG8X, it's the middle ground. for a mobile CB setup in our trucks, RG8X is fine. We aren't wiring up a radio tower.

This is a good calculator for coax (in case you want to compare coax at frequency 27 and 18' length...):
http://www.timesmicrowave.com/cgi-bin/calculate.pl

Grounding can vary by antenna. Some use the mount as the ground, and others come with a ground wire. If your mount is not well grounded, you will have to run a ground wire from it. Take into account the length of the ground wire as well. Try to keep it as short as possible and under 2' in length. Over 2' might not be a problem, but you will have to take it into account when tuning the antenna for low SWR (covered next). I tested 3' to 7' and started seeing issues after 5'.

I ran the ground and the antenna coax into the tail light and down through a hole. I grounded the antenna to the frame. Then I ran the coax up over the wheel well, back down and along the frame, and finally up through a grommet just under the driver’s seat.






Note: If you end up with a lot of extra cable, don't store it in a coil/circular shape. This can cause issues. Instead use a figure 8, or wrap it like an extension cord and tie it in the middle. There is a scenario where coiling the cable is a good thing, but only if done right and in the appropriate diameter. This is for the amateur radio guys, for our simple application of CB, not coiling the cable is the thing to remember.

Also: I had to use automotive sealant around the hole I made in the grommet to prevent leaking. If you do, make sure it's a very flexible sealant.

 

Section 8: Antenna Tuning

A quick note about Standing Wave Ratio (SWR). Basically, it’s a ratio of how much power gets to the destination and how much is reflected back at the CB. If you don’t tune the antenna, you could end up with a high SWR reading and fry your CB.

So, before using the radio, it needs to be tuned. You can use a special meter for this, and it’s very simple to use. Getting in tune, however, may not be.

An SWR meter is an inline meter and will have a patch lead that connects to the radio, and a spot for the antenna to connect to the SWR meter. It should have a CAL knob and FWD and REF switches. The switches are power forward and power reflected.

You could get false readings if you are in a tighter space, so drive out to an open area for tuning.

Grounding the antenna is very important to achieving a low SWR. When grounding the antenna, check to see how it should be grounded (some are mount grounded and some have a ground wire). The length of the ground wire should be taken into account also. Your ground wire should be as short as it can be to reach a good ground location. If you end up running a long ground wire, it could cause a high SWR reading. Try shortening the ground wire and checking again. (But I have tested up to 5' with no issues)

First switch it to FWD and key the radio. It should show some level of deflection, if not, you don’t have power or something might be broken. Turn the CAL knob until the needle is on the infinite symbol.

Then, go to channel 1 and switch it to REF and key the mic. Repeat for channel 40 and take note of both readings. If channel 1 had a higher reading than channel 40, you need to raise the antenna, if lower, you need to lower it. Try to get channel 40 and 1 as low and close to each other as possible.

Once they are about the same, check your channel 20 reading. It should be pretty low.

If all the readings are under 2, you’re safe. If they are over 2, you need to keep adjusting the height of the antenna or check for proper grounding. Most antennas have a top adjustable piece that will allow you to do this without much trouble. Others might require that you start trimming the bottom of the antenna. Follow the directions on the antenna instructions.

After each adjustment. Set it to FWD again and check that you’re still on the infinite symbol before switching it to REF and checking the reading.

I have un-grounded the antenna on this below example to show what a high reading looks like.


If you have tried raising and lowering your antenna and the SWR reading is still very high, you may not be grounded well. Again, try grounding to the frame and take another reading.

If you can’t seem to get it down, try moving the antenna to a different spot. You may be reflecting off the cab, or other solid metal surface. Or you might not have a good ground plane for the type of antenna you are using.

If all else fails, let an expert look at it. Do not use your radio if you have a high SWR! It will fry the radio and warranties do not cover this type of damage. It’s better to let an expert tune it for you.

Later, if you notice that the CB is getting very hot, it could mean that you need to re-tune the antenna. I haven't had any problems yet, though a friend of mine did when his antenna tip broke off and he didn't realize it. So I check mine every now and then to make sure nothing got out of whack

 

Good write up OP

 

I had a license back in KY when I was in HS. But I don't even know where my old HAM rad went. CB works fine for my application.

 

Great writeup.

 

Nice job OP and thanks

 

Sub'd for future use. Thanks!

 

Good shit devil dog

 

Nice writeup. I have a quick question. What type of antenna cable do you run? I know there are different types.

 

Yes, there are, and I run RG8X coax. This is high quality cable and not that much more expensive. The connectors are all a standard PL-259.

Also, there is a general rule of thumb to use either 9' or 18' in length. I would recommend 18' since it seems to be better at resisting interference. And if you end up with more coax then you needed, don't wrap it in a coil/circle to store it, that can actually cause interference.



I used RG8X coax for the power cable since I had some extra and it is very well shielded. I do not need a noise filter with this setup.

 

Nice write up OP. Although I wouldn't recommend mini 8 for anything, it's about as cheap as you can get. Especially if you are pushing any kind of power as it can cause all kinds of issues. Also, the coax does not need to be in any particular length. The ideal length is just enough to get the job done.

 

You're right, I updated my antenna wiring section. I actually ran RG8X for the antenna.

RG8X is fine for power, the gauge of wire is way larger than what's needed for the power and the shielding is what I was after.

In regards to length, I read in some technical manual by Firestik that they did a lot of testing with cable lengths and found that 18' was the ideal maximum for vehicle applications due to mounting locations and such. Though I am not technical enough to understand how they came to that conclusion, but I understand it has something to do with the wavelength at 18'.

 

Hey Chris,
Thanks for all the info!
Quick question, where did you attach the ground on the atenna?