I actually read something about this noise several years ago when I first looked into LEDs. The issue is the driver, not the LED itself.
The driver is what converts the 12/24V from your battery bank to the 3/5V that the LED chip uses. The driver is built into the bulb in most cases. So unless you buy super cheap bulbs, you shouldn't have a problem with it. The same problem exists for the cheap USB power adapters that you can plug into your cigarette lighter in the car to charge your cell phone. Speaking of which, if you have problems with your TPMS in your car, the first thing to do is to disconnect any chargers you have plugged in and see if the problem goes away after driving for a little bit. In cars, the noise of the alternator is basically amplified and broadcast as RF static by the USB power adapter. In boats, you may need to test a couple of things to find out where the noise is generated. But you likely won't find the problem when you are just running off battery power because it is clean DC power already. When you are running off shore power or the alternator from your motor is when you might notice the noise from the LEDS. The first is to test while running the motor. The voltage regulator in the alternator gets you your DC voltage out, but it usually isn't the cleanest and has ripples in the flow that imitate AM noise. The second is to test while on shore power. The inverter that you use to run the lights when you are one shore power works the same way as the voltage regulator on the alternator works, it takes an AC power source and converts it to DC. A good quality inverter will have very little fluctuation in the 12V DC that it provides, but cheap inverters can put out a lot of noise that the LED's drivers will amplify. If you have a problem with interference it will be caused by one of these two devices. One way to combat the noise is to get some RF chokes and put them on each of the lights' power lines. Typically you want them as close to the end of the run as possible so that the wire doesn't pick up RF along the way to the LED, but sometimes that just isn't feasible, so putting the RF chokes behind or just beyond the breaker panel should get rid of most of the noise and it is the easiest location to take care of all of them at once. Any RF that the wires pick up between the choke and the LED should be minimal and really nothing more than what the LED is exposed to already due to ambient RF in the atmosphere. James On Thursday, February 6, 2020, 9:17:35 AM EST, Della Barba, Joe via CnC-List <cnc-list@cnc-list.com> wrote: Some LEDs produce large amounts of RFI well into the VHF spectrum. Interference at HF frequencies is certainly an issue, but most of us aren?t on the SSB all day and the noise is pretty obvious in SSB or AM modes. I can turn lights on and off until it goes away. Noise up into VHF is far more insidious. You might never hear it, but it can severely de-sense FM reception anyway. AIS is tricky, no one listens to AIS, so you will just wonder why you have no targets that are not 1 mile or less distant. LED anchor lights or masthead running lights can be the worst of all, they are right next to the VHF antenna. ? Joe Coquina _______________________________________________ Thanks everyone for supporting this list with your contributions.? Each and every one is greatly appreciated.? If you want to support the list - use PayPal to send contribution --? https://www.paypal.me/stumurray
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