Can't find what you're looking for? We're here to help: (541) 928-1952

Troubleshooting Electrical & Engine Noise

Do you suffer from those annoying noise issues caused from electrical interference? Well, we have some possible solutions for you!

Common Causes of Interference

  • Noise from an electromagnetic noise source such as lights, switches, and arcs in electric wiring or equipment.
  • Signal overload caused by a nearby radio signal that your equipment might not be able to reject. In this case, your system might need additional filters or shielding to attain better performance.
  • Spurious emissions caused by a transmitter transmitting weak signals on a frequency not designed for that transmitter.

Common Fixes

  • If you have a noise blocker or automatic noise limiter feature (NB/ANL) on your CB, make sure this feature is enabled.
  • If possible, try to wire the CB power leads directly to the battery. This will reduce the likelihood of electrical noise from other systems entering your CB through the power leads.
  • Make sure power leads and coax cable are not running parallel to other electrical lines for long distances, as this may result in interference bleeding through. While it's usually not possible to route coax and power leads so that they NEVER come near other electrical components, try to limit this as much as possible.
  • Use high quality coax.
  • Check all of your connections.
  • A popping, clicking, or snapping sound may be caused a bad spark plug. Try testing/replacing. If there is a whirring sound, it could be a bearing or your alternator. It is important to have everything grounded.
  • If, when the antenna is disconnected, you still get static/noise, then you know it likely isn't noise from the antenna side- just make sure that you don't key the mic without the radio being hooked up to the antenna when you do this test!

NR400 - ProComm Noise Clipper CB Radio Noise Suppressor

CB noise filters should be used in conjunction with the preventative steps listed above for best performance.

  • If noise is coming through the antenna side, you could use a noise clipper/noise suppressor such as the NR400, which hooks inline between the radio and antenna and amplifies the signal and reduces the noise from electrical interference. Don't forget to get a jumper coax!
  • On the power side, the IBNF10 noise filter reduces and eliminates engine interference! You can splice this in anywhere in between your radio and the power source.


It's often impossible to eliminate ALL engine noise in problematic vehicles, but the above steps should help reduce it and make your incoming signal cleaner.


Additional Information Regarding Squelch and Noises

CB radios can be affected by engine motions, cellular broadcasts, and electrical wires which can cause white noise and static on the CB, reducing the radio's effectiveness. Aside from the filters, using the squelch function on the radio can help reduce the noise. Squelch is necessary in order to transmit and receive properly but you can adjust the squelch until the noise disappears, then turn the squelch back just far enough to receive a small amount of static.

Addition: Interference Issues Due to External Lights/Strobe Lights or Other Items

  • To troubleshoot where the interference is coming from, you could the process of elimination of disconnecting any potential causes.

  • Check your wiring for damage.
  • Check for any loose terminal connections.
  • If you have a noise blanker option on your radio, make sure that it is on.
  • Make sure that the light/s or other items are sufficiently grounded- maybe try grounding them directly to the battery.
  • Check your connections for the lights.
  • If you have multiple lights / items, try to isolate which one is causing the problem by turning them off one at a time.
  • You could try wrapping your CB radio power wire in tin foil.
  • You could try shielding your radio by using tin foil.
  • You could also try moving your radio or redirecting your wiring.
  • Try using a different radio to ensure that your radio isn't having issues.
  • Try using your system in a different location to make sure that the interference is coming from your vehicle.
  • Try running your power a different way- if directly connected to the battery, try the fuse box or vice versa.
  • Make sure that you have high quality coax.

If you know the source of the noise, you may be able to utilize a Snap-On RF Choke such as the RFC2, RFC3, or RFC4 noise suppressors.

More Information

Radios have different receivers, different filters, as well as different power cords all of which can impact noise interference.

If you know that it is the alternator causing the noise, you could try grounding the alternator itself.  We understand that it would seem like the alternator would be sufficiently grounded, but that is not always the case.  Another solution could be the IBNF10 noise filter.  Also, make sure that you activate ANL (automatic noise limiter) and NB (noise blanker).