Try these steps for locating powerline RFI/TVI:

1. Check all devices in and around the house that could be rfi generators. ie: doorbell transformers, motors, florescent lamps (ballast as well), breakers, etc.

2. Eliminate circuits in the house by flipping breakers. (Turning them off, checking for noise, then turning them back on).

Note: Before going around checking for noise, make a note of the tv channels that are affected. the lower the channel the further away the noise is. The higher the channel, the closer the noise is. (ie: channel 4 or 5 > look a half mile away or farther. If the channel 13 is affected look a block or two away. ect.)

3.After everything in the house has been eliminated. Drive Around and listen to an off am station frequency and locate the loudest noise level.

4. Then get out and walk to several poles using a portable A.M. radio listening for the loudest noise and try to get the number of the pole that has the noise the loudest.

Note: PLEASE DO NOT STRIKE THE POLES WITH ANY TYPE OF OBJECT. This could cause injury and perhaps DEATH! Leave this to qualified Electrical Utility personnel!

5.Once you have found the culprit then call the Power utility co.and report the problem. Include the location (address, landmarks, etc) and pole number! (if any)

Be patient. It may take some time locating the interference. Especially if its intermittent.

Excellent reference from ARRL is: Interference Handbook by William Orr, W6SAI and William Nelson, WA6FQG

Good Luck!