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Old 02-24-2019, 09:49 AM   #1
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Vessel Model: Mainship 30 Pilot II since 2015. Owned wooden 1972 Grand Banks 42 from 1986 to 2015
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Noisy LEDs

The three red LED "bulbs" in the forward end of my hardtop's overhead emit an interfering RF signal requiring me to advance the squelch knob about 20 degrees to lose the noise. I tried the ferrite bead and twisting the power leads routine, but none of that helped. I had heard the Marine Beam LEDs do not emit this harmful RF. I can now report that my new Marine Beam LEDs are noiseless.
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Rich Gano
FROLIC (2005 MainShip 30 Pilot II)
Panama City area
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Old 02-25-2019, 12:27 PM   #2
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It's the tiny onboard power supply, not the LEDs, radiating noise

I'll throw this up until a more skilled EE type chimes in.

The radiated noise causing interference is coming from the (poorly designed or poorly shielded) little internal DC-DC circuit on or in the light assembly, not the LED's themselves. To fix a "noisy" light, you would need to construct a little shielded box around that part of the light assembly.

That tiny power supply mounted in the assembly takes the input DC voltage, converts it to a high frequency, passes it through a small transformer, and converts it back to a different DC voltage before passing it over to the LED's themselves. Lots of ways for high frequency noise to "leak" if not designed and/or suppressed correctly, the real difference between "good" and "noisy" lights. Something Marine Beam has figured out that others have not.

Those plain ~16' LED strip lights on spools arrange their LED's in parallel groups of 3 with a series resistor to work straight from a nominal 12V source without needing an internal converter so therefore shouldn't radiate at all.

I do use a couple of series diodes in the power feed to those strips to drop my house voltage down so my battery charger doesn't shorten the life of the LED/resistor groups when it's charging. The 3 LED/resistor groups don't start to draw current until they see ~8V and then draw relatively proportionately with voltage after that, so having them on while battery charging at 13.5-14V (~6V above turn on) is driving them 50% harder than at a nominal 12V (4V above turn on).

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