The below videos give a real world example of power line noise suffered by Allan VK2CA. The second video shows first hand how you can use a simple VHF/UHF receiver to narrow down the offending power pole.
QRM.guru thanks Allan for providing these videos.
This video illustrates first-hand the horrible sounds that wiped out much of HF for this operator.
This next video illustrates how to close in on the offending power pole.