I have a 400kV powerline about a mile away. Twenty years ago it had become quite noisy - you could see the big glass insulators arcing slightly at night. After lots of complaints to the National Grid they cleaned the insulators, and the noise stopped.
The only time there is powerline noise now is when it has been dry for a while - I guess dirt has built up on the insulators - and THEN there is light rain - That's when the insulators start arcing. Once there has been heavy rain, the dirt is washed off, and it's quiet again. You can tell if it's noise from the powerline if you listen to the noise on AM - you will hear that is has a VERY loud 50Hz buzz . . . it's not like the wideband hash you get from Internet Broadband or from some bad Switchmode PSUs. Our main source of noise here in Britain is from Internet Broadband, which is mainly delivered via the old overhead copper telephone wires (which make great topband antennas, radiating the noise for miles). They have started to replace these with Fibre Optic Cables . . . so hopefully the noise will be gone in 5 years! 73 Roger G3YRO _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
