Originally Posted by hdtv6
Does the fan also shut down when the a/c unit shuts off? Is there more than just your house on the transformer that feeds you home with power? If so, the impulse noise could be in one of these homes. One last thought: impulse noise caused by major appliances usually do not last more than a few minutes; surely no longer than 15 minutes at a time. Of course, this theory does not hold water is there is an internal problem such as an electric water heater with a ruptured heating element that could be leaking current even when it is supposedly "off". I hear that CFL lights can cause interference, especially when something is wrong with them. Light dimmers can also cause interference even when they seem to be working "just fine". Turn off all lights to make sure this is not the problem. Do not purchase light dimmers unless they contain "zero crossing detectors".
You say nothing has changed; are you sure? Anything new moved to the attic? A new picture hung on a wall with a nail through the antenna wire in the wall? A new mirror with its silver (metallic) coating? I am willing to assume that none of these types of things have happened, and I would also think that the interference is external to your home. Again, this could be almost anything that generates an RF signal even if it's not supposed to do so (computers, electric shavers, etc.).
Do you have access to a battery operated TV set? If so, use its built in antenna and set it close to (at least 3 feet away), but not on, your main TV set. If the main set has the problem while the battery set does not, then the problem is most likely impulse noise in the power line. If both sets have the problem at the same time, then the interference is most likely being picked up over the air (meaning it's an RF signal).
1) Yes fan does shut down
2) Yes, I live in suburbia
3) No light dimmers
4) Yes, nothing has changed. No nails in walls. No metallic mirrors.
I did some experimenting today. Unmounted the antenna in the attic (CRAP IT IS HOT!!!) and put it inside, high in the house. A little improvement. Then I mounted it outside, worst reception.
No access to a battery operated TV, but even better. In the kids room there is another HDTV. He only uses it for his Xbox and Netflix. I decided to just connect the cable to it (NOT attached to the antenna, it's just sitting up in the attic) and BAM, crystal clear.
My next step is to bring that TV to the entertainment system in the living room (where the TV in question is now) and see if I get the same results.
I am off t find a live stream to watch football because I can't catch a local channel...