There are quite a few reasons as to why communications equipment causes interference to other electronic equipment as well as to why radio equipment receives interference. Here we will attempt to touch on a few of the more common ones and show you some fixes.

Television Interference

The most common type of interference being caused to televisions by radio equipment  is the distance between the your transmitting aerial antenna and the television reception device.

One way to remedy this is to place a 'high-pass' filter in series with the television co-axial cable going into the television. The arrangement of capacitors and inductors in the filter pass higher frequencies while reducing lower frequency signals. The filters are also made to go inline on your base station coax and do work very well on stopping the RFI.

Another cause, rare but does happen, is the transmission of your signal can pass into the wiring in your house and follow it to other outlets or even out to the pole to another house. This usually occurs with real old or bad coating on the wiring. A good power line filter or conditioner can filter this out

Audio Equipment Interference

Capacitors can be used to pass only audio frequencies but not allowing higher frequencies to pass wired into the audio system. There are also very good filters available at most electronics stores.

Mobile Radio Interference

Automobiles are also a breeding ground for interference usually not generated by the  radio equipment onboard but received by it instead. The car ignition system generates noise because of the high voltages switching to fire the spark plugs in the engine. Alternator whine is another typical and annoying interference into the radio equipment. If you have problems with engine noise in a mobile installation there are several things you can do to reduce or eliminate the problem.
 

• Make sure you've completely installed your CB and the antenna is grounded properly.
  
   
• Try checking the amount of noise with and without the antenna connected.
• If the noise is greater when the antenna is connected, the source is more than likely in the ignition system.

• If the noise remains unchanged after disconnecting the antenna, then the source is more than likely in the radio's power supply.
  
  For Ignition Noise
  There are several parts of the vehicle that can act like RF noise transmitters if not properly grounded. Check and make sure the engine block, hood, alternator, and exhaust system is well grounded. Capacitors can be used to suppress alternator noise.
  Ignition noise may be further reduced by installing quality spark plug wires and good resistor plugs.
  
  For Power Supply Noise
  Make sure you have a capacitor attached to your ignition coil, alternator, and distributor. These will act as filters right at the source of the noise.
  Make sure that your antenna coax and power cables are as far as possible from the interference sources we have discussed.
   

Summary
A well grounded system is probably one of the best weapons in fighting RFI. Make sure you ground your antenna tower to a good ground rod. This will also help with alot of static from ground noise. Making sure you ground your radio equiptment to an outside ground rod will help too. Taking your equipment to a tech periodically and making sure it is in proper adjust will also help with your radio putting out a good clean signal and cut down on bothering neighbors radios and phones. A nasty splattering signal will get into a lot of things it shouldn't. And of course, One of the best ways to clean up RFI, is to purchase a more expensive radio with a better noise suppression circuit.

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