Voted UK No.1 for CB Radio
TVI filters to fit on your radio and TV, plus power lead filters to suppress noise in your power cable.
These are used to try to eliminate interference caused by radio transmissions to TV's, HiFi's etc.
Low Pass filters fit on the radio, which is obviously easier but unfortunately often ineffective.
High Pass and Notch filters fit on the affected TV. These are usually much more effective, but unfortunately it can work out expensive if you are interfering with several TV's.
These fit in the 12V power lead to your radio to try to eliminate any electrical interference which is reaching the radio via the power lead.
Usually these are quite effective against alternator noise, but not against interference generated by much of the electronics in modern vehicles.
If the interference is reaching your radio through the antenna system, then obviously these filters will make no difference at all.