Interference to you.
For many years this was a one way street. Any TV viewer close to a reasonably powered ham radio station would be liable to experience patterning, breakthrough and all round degradation of picture. This is still true today and you may need to be poised to deal with problems. There’s plenty of help on this topic. But these days this is a two way street. The proliferation of ADSL running in telephone wires across the street, wireless LANs and worst of all, power-line home network systems, the public is generating consierable interference to radio hams. In addition, plasma televisions, computers, switched mode power supplies and so forth, all add to the general RF noise that prevents decent reception on HF. If affects radio hams and SWLs a like. Obviously this may be worse in some locations so it’s worth checking before you invest in equipment. Indeed it may mean that portable operation is your only option. Fortunately the RSGB are voicing complaints about PLTs to ham radio reception to OFCOM. Time will tell if they happen to succeed.
Causing Interference (known as RFI or TVI)
Ham radio transmissions can, and do, generate relatively high levels of electromagnetic waves in the close proximity of TV and Radio antennas. IN the past, particularly with analogye TV, a ham radio station could be a nuicance and totally spoil a neighbours viewing. The moive the Digital TV has made life a little easier as the effects are less destructive, although very high levels can cause pictures to freeze. The RSGB has section to help overcome these type of problems.