T4D: RFI and its complications, resolution and responsibility

A break in a cable television transmission line may result in TV interference when the amateur station is transmitting, or interference may occur to the amateur receiver.

If you are told that your amateur station is causing television interference, first make sure that your station is operating properly, and that it does not cause interference to your own television.

The first step that should be taken at a cable TV receiver when trying to prevent RF overload from an amateur HF station transmission is to tighten all connectors and inspect the cable system transmission line.


Receiver overload interference is caused by strong signals from a nearby source.

If your neighbor reports television interference whenever you are transmitting from your amateur station, no matter what frequency band you use, receiver overload is probably the cause of the interference.

If signals from your transmitter are causing front-end overload in your neighbor's television receiver, the owner of the television receiver is responsible for taking care of the interference.

A high-pass filter should be connected to a TV receiver as the first step in trying to prevent RF overload from an amateur HF station transmission.


Harmonic radiation is unwanted signals at frequencies that are multiples of the fundamental (chosen) frequency.

If your neighbor reports television interference on one or two channels only when you are transmitting on the 15-meter band, harmonic radiation from your transmitter is probably the cause of the interference.

A low-pass filter might be connected to an amateur HF transmitter to cut down on harmonic radiation.

If harmonic radiation from your transmitter is causing interference to television receivers in your neighborhood, you alone are responsible for taking care of the interference since your transmitter is causing the problem.