Testing a CB Antenna Ground with a Multimeter
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This video demonstrates how to
This video demonstrates how to use a multimeter to test the electrical ground on a CB antenna mount. Check out our CB World Help Center Article: https://www.wearecb.com/testing-cb-an...
How to Ground a CB Antenna:
Perhaps you’re doing an original installation and want to know how to ground a CB antenna. Perhaps you’ve already installed it, tested your Standing Wave Ratio (SWR), found it too high and want to improve your CB antenna grounding. Or, perhaps you’ve noticed that you’re not getting the CB radio performance that you should be. In any case, the first step is to test your CB antenna’s grounding.
Testing the CB Antenna Ground:
You’ll need a multi-meter to check your CB antenna's ground. If you need to know how to use one, read our article on Testing for Continuity. An easy way to test your antenna's ground is check continuity between the CB antenna mount and your vehicle ground, because if the antenna mount is well grounded, so is your antenna.
To test for continuity of electrical signal, you will need to touch the probes for your multi-meter in two locations. You can use either the red or the black probe to touch either location. The following provides step-by-step guidance for testing the CB antenna ground.
Step-by-Step Instructions: Grounding a CB Antenna:
Touch the first probe to the CB antenna mount in order to test the CB antenna ground
Where to Put the First Probe
Lay the first probe where it touches your CB antenna mount. Lay the probe flat across the mount surface, being careful not to touch the vehicle with the probe.
Where to put the 2nd probe when testing the antenna ground
Be cautious working around your battery as you complete this step. The second probe should touch the negative terminal on your vehicle's battery (marked with a minus sign). Take care not to touch the positive terminal (the one marked with a plus sign).
Alternative location for placing the 2nd probe when testing cb antenna ground
If it’s not possible to reach both the CB antenna mount and the negative terminal of the battery with the probes, find a good ground on the vehicle (such as the one pictured) and use that for the second probe's contact point.
Interpreting the Results of the Continuity Test
If your CB antenna mount has a good ground, the multimeter needle should move all the way to the right when the probes contact these two locations. If you get very little or no needle movement on the multimeter, test that your meter is working properly by touching the two probes together. If the needle moves all the way to the right, the meter is working properly. So, if the multimeter is functioning and you’re getting little or no needle movement, you’ll need to try to improve your CB antenna grounding. Good grounding establishes a ground plane for the system.
How to Ground a CB Antenna Mount
If your antenna mount is one that is designed to accept a coaxial plug (such as the 2 ended PL259) or a PL259 with a fire ring on the other end (such as the FireStik MU8R Single Antenna CB Coax) then your work is easy. Just make sure that the mount is attached to the frame of your car or truck securely, and you should be good to go. If for some reason you need to correctly attach an end to the coax cable (perhaps you're making your own), this reference has pictures step by step for attaching both screw-on and crimp style connectors to a coax cable. Here is a technical reference for what’s inside the coaxial cable with a picture of what you’ll encounter if you strip it back.
What kind of strapping hardware do I need?
If your antenna doesn’t accept a coaxial plug then you’ll need to provide a ground another way. Although some CB owners use 10-gauge wire for a ground, braided ground strapping is preferable. That’s because of reactance. Reactance can change the wire into an antenna rather than a radio frequency (RF) ground, which is the opposite of what you’re trying to accomplish.
Where to Ground a CB Antenna
When you’re deciding how to ground your CB antenna system, recall that the antenna will be more efficient when you use the most metal on your car. To pull the metal together, you may need to bond the metal parts by using more than one ground strap in different locations. That will also provide insurance against the accidental floating of the negative power lead. You don’t want to run a strap all the way from the mount to the battery for the same reason.
Worth mentioning again is that the most important part of getting a good ground is to attach the ground to metal rather than plastic or other materials.
To get a better ground, you could move the mount and the antenna to a different location with a better ground. Or, you could add an additional grounding strap to the mount. If you aren’t concerned about appearances on your vehicle where your antenna is mounted, you could (gasp) scrape the paint off underneath the mount to have a metal-to-metal ground, but would be the least desirable option to most of us.
How to Ground a CB Antenna:
Perhaps you’re doing an original installation and want to know how to ground a CB antenna. Perhaps you’ve already installed it, tested your Standing Wave Ratio (SWR), found it too high and want to improve your CB antenna grounding. Or, perhaps you’ve noticed that you’re not getting the CB radio performance that you should be. In any case, the first step is to test your CB antenna’s grounding.
Testing the CB Antenna Ground:
You’ll need a multi-meter to check your CB antenna's ground. If you need to know how to use one, read our article on Testing for Continuity. An easy way to test your antenna's ground is check continuity between the CB antenna mount and your vehicle ground, because if the antenna mount is well grounded, so is your antenna.
To test for continuity of electrical signal, you will need to touch the probes for your multi-meter in two locations. You can use either the red or the black probe to touch either location. The following provides step-by-step guidance for testing the CB antenna ground.
Step-by-Step Instructions: Grounding a CB Antenna:
Touch the first probe to the CB antenna mount in order to test the CB antenna ground
Where to Put the First Probe
Lay the first probe where it touches your CB antenna mount. Lay the probe flat across the mount surface, being careful not to touch the vehicle with the probe.
Where to put the 2nd probe when testing the antenna ground
Be cautious working around your battery as you complete this step. The second probe should touch the negative terminal on your vehicle's battery (marked with a minus sign). Take care not to touch the positive terminal (the one marked with a plus sign).
Alternative location for placing the 2nd probe when testing cb antenna ground
If it’s not possible to reach both the CB antenna mount and the negative terminal of the battery with the probes, find a good ground on the vehicle (such as the one pictured) and use that for the second probe's contact point.
Interpreting the Results of the Continuity Test
If your CB antenna mount has a good ground, the multimeter needle should move all the way to the right when the probes contact these two locations. If you get very little or no needle movement on the multimeter, test that your meter is working properly by touching the two probes together. If the needle moves all the way to the right, the meter is working properly. So, if the multimeter is functioning and you’re getting little or no needle movement, you’ll need to try to improve your CB antenna grounding. Good grounding establishes a ground plane for the system.
How to Ground a CB Antenna Mount
If your antenna mount is one that is designed to accept a coaxial plug (such as the 2 ended PL259) or a PL259 with a fire ring on the other end (such as the FireStik MU8R Single Antenna CB Coax) then your work is easy. Just make sure that the mount is attached to the frame of your car or truck securely, and you should be good to go. If for some reason you need to correctly attach an end to the coax cable (perhaps you're making your own), this reference has pictures step by step for attaching both screw-on and crimp style connectors to a coax cable. Here is a technical reference for what’s inside the coaxial cable with a picture of what you’ll encounter if you strip it back.
What kind of strapping hardware do I need?
If your antenna doesn’t accept a coaxial plug then you’ll need to provide a ground another way. Although some CB owners use 10-gauge wire for a ground, braided ground strapping is preferable. That’s because of reactance. Reactance can change the wire into an antenna rather than a radio frequency (RF) ground, which is the opposite of what you’re trying to accomplish.
Where to Ground a CB Antenna
When you’re deciding how to ground your CB antenna system, recall that the antenna will be more efficient when you use the most metal on your car. To pull the metal together, you may need to bond the metal parts by using more than one ground strap in different locations. That will also provide insurance against the accidental floating of the negative power lead. You don’t want to run a strap all the way from the mount to the battery for the same reason.
Worth mentioning again is that the most important part of getting a good ground is to attach the ground to metal rather than plastic or other materials.
To get a better ground, you could move the mount and the antenna to a different location with a better ground. Or, you could add an additional grounding strap to the mount. If you aren’t concerned about appearances on your vehicle where your antenna is mounted, you could (gasp) scrape the paint off underneath the mount to have a metal-to-metal ground, but would be the least desirable option to most of us.
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