I am causing breakthrough

Nowadays it is unusual for interference to be caused by a faulty transmitter, though occasionally interference from harmonics and other spurious emissions are encountered.

Introduction

Information on this type of problem can be found in a number of EMC leaflets. This section deals with breakthrough caused by the fundamental of the transmitter getting into nearby electronic equipment and causing it to malfunction. Most modern electronic equipment is designed to have a reasonable immunity to radio frequency (RF) fields, but this may not be enough to cope with the large fields which can arise from a nearby amateur transmitter.

The most important factor in reducing breakthrough into local radio and electronic equipment is good radio practice and particularly the siting of antennas. EMC Leaflet No. 10: Avoiding Interference to Nearby Electronic Equipment sets out the factors you should consider if you live in close proximity to neighbours and wish to minimize breakthrough problems. In the paragraphs below we provide a suggested approach in dealing with complaints of interference. More details can be found in the RSGB publication The RSGB Guide to EMC.

The first step

—is to confirm that no equipment in your own house is affected by your transmissions. Put simply, if you cannot resolve breakthrough into your own domestic electronic equipment, you are starting from a poor position in discussions with your neighbours.

Where your transmissions are affecting your other equipment, try to resolve the problem through application of the relevant filters.

Look for the obvious sources of problem—ask yourself “what is acting as an antenna to pick up my signals?” Very often this will be long loudspeaker leads to audio systems (fit ferrite toroids near the audio amplifier output), the coaxial down-lead to the television (try a “braid-breaker” filter), or the mains cable to the affected equipment (again, try a toroid at the point that the mains cable enters the equipment.

Breakthrough onto telephones can be tricky—see EMC Leaflet 5: Radio Transmitters and Telephones. Again, ferrite toroids fitted to the telephone cable near the handset can help. But some telephones are much more susceptible to breakthrough than others. It may be helpful to consider having a very basic handset (with minimum amount of electronics) to confirm the source of the problem. Disconnect all telephones, modems etc from your internal telephone network, and connect the simple phone. Confirm that the breakthrough is cleared—if not, fit toroids to that handset until it is. Then progressively add back telephones on the network, one at a time, checking each time that the breakthrough is cleared. Remember that one telephone that is susceptible to RF can add back interference on to the whole network. When one handset added causes breakthrough to return, try toroids, but be prepared to discard the offending handset if all else fails. Ultimately you should have a complete telephone network free from breakthrough.

Breakthrough onto security alarms is another cause of problem, andEMC Leaflet 3: Dealing with Alarm EMC Problems provides some useful guidance.

Now to the real work

Once you have cleared ALL cases of breakthrough in your own home, the difficult part begins! Before you speak with your neighbour, you may find it useful to consult your Regional EMC advisor

Resolving EMC problems calls for great diplomacy with your neighbour. Often the initial reaction is that the problem must be with your transmitter, as without it, reception is faultless. Read EMC Leaflet No. 1: Radio Transmitters and Domestic Electronic Equipment , and let your neighbour have a copy to read. Explain that you are willing to help, and that a few simple steps involving no modification to his equipment, may resolve the issue. Add that your own TV/radio/alarm/telephone (as appropriate) is unaffected by your transmissions.

You should NOT consider any internal modifications to your neighbours’ equipment. But you could offer to try toroids on the downlead, speaker leads, telephone leads and mains leads of affected equipment, or a braid-breaker on the TV antenna feeder. If the problem is a security alarm, read again EMC Leaflet 3: Dealing with Alarm EMC Problems

If these basic steps fail, then it may be a case of asking the retailer to provide some help. Equally, there is the option of the neighbour complaining to Ofcom via the form ‘Interference to TV and Radio Reception’, Ref. No. Of22.

EMC leaflets that will help you in your work include:

Please note: These pages are intended for members of the Radio Society of Great Britain, but are available to non-members on the understanding that any information is given in good faith and the society cannot be responsible for any misuse or misunderstanding.