CFT lamp interference with long wire antenna

[Nickthedentist]

Originally Posted by David Tilley

The noise that I do get from them goes if I plug the microwave in but don't switch the mains socket on that feeds it. Work that one out!

Maybe because there's a filter network in the microwave that's permanently connnected to its mains lead, and its socket has only single-pole switching, leading, in effect, to some capacitor being connected between N and E

[maitiustandun]

Originally Posted by Nickthedentist

Maybe because there's a filter network in the microwave that's permanently connnected to its mains lead, and its socket has only single-pole switching, leading, in effect, to some capacitor being connected between N and E

are you sure the wall socket is wired correctly?is phase connected to socket switch,regards maitiu.

[julie_m]

Originally Posted by David Tilley

The noise that I do get from {My CFL's} goes if I plug the microwave in but don't switch the mains socket on that feeds it. Work that one out!

OK, I'll bite. Here's my hypothesis:

The switch in the socket is only interrupting the live pole. The µW's internal EMC filter has a capacitor between neutral and earth, which is just enough to prevent the neutral wire of the lighting circuit from radiating anything.

If that is what's really happening, then a 10nF Y-rated capacitor installed in the fusebox or a ceiling rose should have the same effect.

[hmv1944]

Hello,
An update on my original problem; RF interference on MW & LW after darkto the extent that programmes were unlistenable, blamed rightly or wrongly on compact flourescent lamps. On inspection the three core replacement mains cable I had installed had, contrary to my memory, not been connected to anything leaving the set unearthed! So, I have done the following with good effect: an external earth of a metre and a half of water pipe hammered into a flowerbed connected to the set's earth socket, sixty feet of external antenna draped along a hedge, a British Telecom filter plug adapter in the mains lead connected to the house mains earth, the mains lead to the set wound five times round a ferrite toroid (one sold for the purpose). I have left the set unconnected to the mains earth. The result is greatly improved after dark reception with none of the chopped noise there used to be; the only noise tonight being some background computer hash (and Radio Moscow on 199 kHz).
Alan.

[Al (astral highway)]

Originally Posted by hmv1944

...and Radio Moscow on 199 kHz.

Yes, and very strongly, too! Glad you got the problem fixed.