Amateur and CB radio operate on different frequency bands from those used by radio and television stations. However, disturbance to radio or TV reception can occur sometimes because:
- Equipment cannot reject unwanted transmissions
- Equipment or antenna installation is faulty
In some cases, deficiencies in Amateur or CB transmitter systems can cause interference to radio and TV reception.
First identify whether the reception problems are due to:
- defects in the TV antenna installation system
Identifying the source of disturbance to digital TV reception is more difficult. A TV antenna installer is able to diagnose reception problems.
Resolving the reception problem
Radio and TV interference involving Amateur and CB radio is a shared matter for:
- the person affected by the interference
- the transmitter operator
In most cases, those involved need assistance from service professionals to resolve the matter.
Operators whose transmitters are involved in an interference problem are encouraged to work with people affected by the interference to resolve the issue.
The ACMA may take appropriate regulatory action if a person causes substantial interference to radiocommunications.
The effect from Amateur and CB radio signals may be eliminated or minimised by:
- ensuring the standard of the receiving installation provides adequate reception in the area
- ensuring a suitably installed and maintained outdoor antenna and antenna cabling is used
- ensuring masthead and distribution amplifiers, where used, are fitted with filters designed to reject unwanted signals
- locating the outdoor antenna as far away as possible from the antenna of the Amateur or CB transmitter
- fitting of appropriate interference filtering devices to the affected equipment
- placing filters between the antenna and the television receiver or digital set-top box
- placing filters in the electricity mains lead
The operator of the Amateur or CB station involved can provide advice about their frequencies of operation when selecting an appropriate filter. Also, you may need to consult a TV antenna supplier or antenna installer to choose a signal filter for your situation.
Warning: Under no circumstances should you attempt to repair or modify any electrical device unless you are qualified to do so.
Amateur or CB transmitter operators
Operators of Amateur or CB transmitters may be able to minimise the potential for interference by:
- increasing the physical separation between the transmitting antenna and TV or radio receiver antenna and cabling
- installing an effective earth or ground plane for the antenna
- installing the transmitting antenna away from metal structures such as roofing, gutters and downpipes
- using a balun transformer, common mode choke and ferrite beads on the antenna cable
- running antenna cables down from vertical antennas and at right angles away from horizontal antennas
- employing additional radio frequency filters appropriate for the frequencies of operation
- using a different transmitting antenna type, location, and orientation
- reducing the transmitter's output power—only use the power level that is necessary and not maximum power
- selecting a frequency of operation compatible with broadcasting stations in the area to avoid the impact of harmonic related emissions
- properly matching the transmitter to the antenna
- using a low impedance radio frequency earth connection for the transmitter and associated equipment.
- using transmitters other than during prime viewing or listening times.