Hints on how to Solve TV Interference Problems

Caused By Radio Transmitters

Many amateur radio operators experience this scenario at least once in their lives: Their neighbours experience TV interference, and the radio operator is to blame (as always). This may, or may not be the case, but it does need to be fixed - and the radio inspector is always much happier if you do it yourself! So here are a few easy things to look out for:

1. Is the neighbour's TV antenna pointing the right way? Don't laugh, as many people receive "ghosts" of the main signal, and therefore have a bad picture to start with. If the TV station transmitter is towards the north of the house, make sure that the antenna points north too (if it is directional of course)! If this means that the rx antenna is pointing towards your station antennas, try moving it 10 or 15 degrees off to the side, and see if an above average picture can still be received.
2. Is the antenna installation a good one, and is a masthead amplifier used? Masthead amplifiers (TV preamplifiers) are terrible devices, as they are more likely to amplify noise, ghosting and other unwanted signals than they are to amplify wanted signals! If the amp has a gain control, try winding decreasing it a little bit to quell the noise level. If possible, try eliminating it all together, or putting it closer to the antenna (it is no use putting one near the TV). If that isn't possible, have a look at the installation itself. Often, if it is a DIY installation, there will be badly crimped connectors, loose bolts, huge lengths of transmission line, bends and kinks and balanced line running down metal pipes etc. If this is so, gently ask them to get a technician to look at it...
3. Have you installed a low pass filter on the HF transceiver? This will decrease the second harmonic (if it is over 30MHz) by over 40dB, and the subsequent harmonics by larger amounts. This can be one of the best ways to reduce interference from HF rigs ever invented! Make sure that you install it as close as you can to the radio though.
4. Is a high pass filter installed near the TV? Most probably, the answer will be 'no', but this is another easy way to decrease interference from HF rigs. It will probably cost quite a bit of money, which may upset your neighbour. Maybe a few cartons of beer or a barbeque would suffice? :-)
5. Are power leads coiled in toroids? If you live very close together, you probably share the same step-down transformer as your neighbour/s, and therefore may experience feedback down the power circuit between your houses. This can be greatly reduced by winding all transmitter and receiver (TV) power leads in toroids, or even around a toilet roll if you don't want the expense!
6. Are their dirty or corroded connections? Especially if you live in a coastal area, this can be a major problem. Try disconnecting them, and dusting them off with a dry cloth or soft dust-brush. This is a solution for 'diode joints', which are caused by two dissimilar metals reacting with each other. Try to cover them in waterproof tape if they are outside, to stop rust and corrosion.