Selecting the Correct Coax Cable
CB coax cable is necessary to connect your antenna to your radio.
The coaxial cable running from your radio to the antenna is VERY important. Everything you transmit and receive must travel along it's length. All too often, the coax is ignored and performance suffers because of the lack of attention it receives.
We recommend 18 feet of coax even if you don't need that much. If you use a length that is shorter or longer, you might risk having trouble achieving good SWR readings. Properly store any excess coax in a figure 8, about one foot in length, and bound in the middle- it should look like a long, skinny 8. Do not store your excess coax where there is any loop upon itself nor bound in a coil. Doing so is basically creating another antenna coil and can skew or falsify your SWR readings. Improper coax storage is one of the top reasons why people have high SWR readings.
It is very important to understand that there are many different types and quality of coax cable.
Hopefully, this will help you so that you can pick the best coax cable for your particular needs.
To begin, note that not all coax cables are exactly like this but all have the same concept:
The coax doesn't actually connect directly to your antenna, but rather to the antenna mount. This allows the center wire of the coax to remain isolated from the outer ground.
There are different types connections at the ends of coax. Selecting and using the right connection will make your installation easier.
- PL-259 (Barrel) This type of coax connection is the most popular type of connection because this is a standard type of connection to plug into most CB radios. All CB coax will have this type of connection on at least one end. The PL259 is a male end. An SO239 in a female end.
- Plug to Lug PL259 on one end and hoop connection on the other end.
- Ring Style: The ring style connection offers a few advantages over the PL-259 connection. The ring is made of plastic which holds up to weather and moisture, therefore reducing the chances of rust. Also, once installed, the coax runs at a 90 degree angle from the mount which gives it a clean look and low profile so this connection is great for mounting with limited space.
- FME Removable Ends: If you are concerned about routing your coax through your firewall or other small spaces, an FME removable end might be just for you! Having an end that removes from the coax makes routing a breeze. These simply screw on and off the ends. Also, check out this coax which has the nip connector at the end!
- RG-58 (STANDARD COAX)- Solid center - 50 ohms
- RG58U- Features a solid center - 50 ohms
- RG-58A/U- Features a flexible stranded center - 50 ohms
- RG-8X (PREMIUM RECOMMENDED COAX)- More durable and thicker, stranded center - 50 ohms
- RG-8U - Thick, solid center - 50 ohms
- RG-59 (DUAL ANTENNA COAX) - Flexible stranded center
- RG59U - Solid center
- NGP COAX- See part number K8NGP or NGP Kits
- NOTE: Stranded centered coax is considered higher quality as there is less chance for damage to the core. For example, solid cores have more of a chance of getting slight cracks in the core which cause breaks in continuity leading to high SWR.
There are some important things to remember when choosing a CB antenna coax:
Make sure the connectors on your coax match your antenna mount. You will always have at least one of the big, screw-on PL259 connectors on one of the coax, but the other end can have a PL259, center and ground wires with lug connectors, or single ring connectors like Firestik's Firering.
Use a co-phase harness for dual antenna installations. A single coax is 50 ohms. A co-phase harness is 72 ohms before it splits into 50 ohms for each antenna. This is important for a good SWR. If you try to connect two single coax lengths to a T connector for dual antennas, you may run into high SWR issues.
Select the correct coax length. Many antenna manufacturers somewhat pre-tune the antennas utilizing 18 feet of coax which is why we generally recommend 18 feet of coax even if you don't think that you need that much. Just be sure to porperly store any excess coax in a figure 8, about one foot in length, and bound in the middle- it should look like a long, skinny 8. If you do select a coax length different than the 18 feet, there may be additional antenna adjustments that you will need to make in order to achieve good SWR reeadings. Want to know more? Check out what Firestik has to say about it.
Also, if you extend your coax, there is some signal loss that occurs. Usually, this is not noticeable, however, it is important for you to know.
Use NGP cable for NGP antennas. Using no ground plane antenna cable for a traditional antenna (and vice versa) will give you high SWR problems. If you already have a NGP coax and need to extend it (possibly needing a KPL258X connector), you can do so by using RG8X coax but keep in mind that you will have some loss. Most of the NGP kits have specialized RG58 coax. If you cannot extend the coax for your NGP system or can't make an NGP setup work for you, you could install a metal plate to create a ground plane and use a standard antenna.
Match the impedance of the system you are working with.
For example, television and computers are 75 ohm impedance while 2-way radio systems (such as CB radios) are 50 ohm impedance.
- RG-6/U 75 ohm
- RG-8/U 50 ohm
- RG-9/U 51 ohm
- RG-11/U 75 ohm
- RG-58/U 50 ohm
- RG-59/U 75 ohm
Consider the shielding. Shielding helps to preserve your signal quality by preventing "noise". The more shielding you have, the better the signal quality.
Proper Use and Storage of Coax
Verify that your coax is not crimped, bent, or crushed. Coax is a critical component.
Store any additional coax in a long shape like a figure 8 style, about a foot in length, and loosely bound in the center with a zip tie. Improper storage of your coax (such as a circular style) could result in RF (radio frequency) issues that could interfere with your signal.
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