Yachting and Boating World forums: LED bulb causes static on VHF

LED bulbs with multiple actual LEDs get more efficiency by regulating the current with a switch mode type controller. This means that the power is switched at high frequencies (up to a few megahertz) The switching is very rapid such that harmonics of the switching frequency are generated. Usually this high frequency energy is contained in the fitting and stopped from radiating on the power line by capacitors and inductors.
I guess the proximity of the antenna to the LED fitting is the problem.

I would assume that if you disconnect the antenna cable from the VHF that all interference stops. Indicating that it is coming down the antenna cable. If it is still present then it may be coming in via the power wiring.
If it is coming in via the power wiring then capacitors across both the wires to the LED and the wires to the VHF power might help. Use capacitors around .1 microfarrad rated at 200 volts or more wired from +ve to-ve. Better filtering can be done by winding a few turns of the power wire around a ferrite core with another capacitor on each end of the inductor to ground -ve.
Ferrite is a black hard substance found in the aerial rod of an old transistor radio or in doughnut shapes in computers especially power supplies or can be bought cheaply from electronics suppliers.The ferrite increases the inductance of a simple coil by many times as it is made of finely divided magnetic material like iron dust.
Having said all this the LED should have interference suppression as I described likewise the input circuits of the VHF so you may have to change the bulb back to incandescent or move the aerial. olewill

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