Originally Posted by chewy
In reality how badly does the EMF off LED's really affect our instruments?
It depends on how the LED is regulated, as said previously. But cost isn't an indicator of whether or not you'll get radio interference. Some quite expensive LEDs have buck regulators that operate at a high enough frequency to interfere with AIS and VHF radio. There have been reports of total radio and AIS blackouts when LED nav lights are switched on - so worth checking, especially if your antenna is sharing the radio arch with an LED nav light.
You can also get interference on AM/FM radios.
I think more and more LED sellers are realising there's a problem and making sure their particular product is OK. Probably won't be a problem by the time they get round to writing up the CE specs!
There does have to be advice out there to prevent people simply sticking a white LED behind their coloured lenses - thereby displaying red and blue.