No diodes.. The problem is that in order to regulate the voltage to keep constant illumination and to protect from over voltage and burnout.. And it's those switching regulators that are causing the problems with the power leads themselves acting as antennas radiating all this wideband noise that is killing radio and TV receivers, as well as VHF Wx and amateur radio receivers. The fix is to remove these switching regulators and just current limit them with resistors. The are regulators out there used for RC aircraft that are very very clean (they have to be), but they're ~$30 ea.