The so called LUXEMBOURG EFFECT is often discussed by dxers.

Just what is the Luxembourg effect.

Probably the best example at these lattitudes was the ghostly audio from Atlantic 252 on the RTE carrier on 567. This was quite loud at times, eg during news, weather and other quieter parts of the modulation of RTE.

When RTE took over the 252 frequency a few years ago, I recall saying at the time that there would be no more Luxembourg effect. Not quite true. Whatever method they use to feed the LW site, it lags 567 by a couple of seconds. So the effect is still there, reported recently by a dxer in the UK (Nov 2007).

This effect is not due to receiver overload. It is heard even on a basic portable radio.
Neither is it due to any mixing/ breakthrough at the transmitter site.
The transmitters are physically many miles apart.

I have reproduced an article from the 1938 Handbook of Wireless Telegraphy on the subject.