Radio static

[shanker]

When I'm on a sail and listening to the Blue Jay's game on the radio it is wonderful. Until I turn on my running lights. Once I turn them on, I get a ton of static over the radio. And it's only on the am band. If I switch to FM, the static disappears. Is there and explanation for this? I do have LED lights and I hear they can cause static but wouldn't that affect both am and fm? Would this be some sort of grounding issue?

 

[Fred]

Do you have dimmers on the light circuits? Is the engine running when you get static? Is there anything else on your light circuit? AM and FM at affected differently by radio frequency interference (RFI).

 

[scotmcpherson]

Install a ferite core on your power lead to the radio.

 

[Ken Cross]

If this appears when your engine is running only, it's likely a bad diode in the alternator. This is a common problem and under these conditions your charging is inefficient and will be pretty low. To check for alternator whine I'd vary the throttle and see if the sound changes with it.

Light dimmers don't sound right as no one dims running lights.

If not the alternator, I'd be looking for a poor shared ground. Grounds are the item most often overlooked.
Ken

 

[heritage]

Some of the older LED bulbs will cause static on VHF. Could also affect AM radio.

 

[Don S/V ILLusion]

Install a ferite core on your power lead to the radio.

That cures conducted noise but not radiated noise. The last poster has it correct. Many LEDs are notorious sources of RF radiated noise. Even some new ones. For the trivial energy saving these bulbs net, the consequences are often not worth it.

It sounds from the description that the bulbs are the cause which is more easily heard on AM signals but an also affect our FM VHF radios, particularly on weak signals.

 

[Sailor_Jeff]

.... For the trivial energy saving these bulbs net, the consequences are often not worth it....

Trivial? Perhaps some LEDs don't save much, but mine use one tenth the amount of energy and this means I don't have to run the generator as much to recharge batteries. Some of the places I go, getting diesel or gas is "difficult"....

Worth it? Well, guess that has be be evaluated by each individual in their circumstance, but, I have noticed a minor problem with AM, even my battery powered radio, so no power cord to put Ferrite on. But, I might try some ferrite cores and twist the wires around them at each fixture. I'll bet, now that I think about it, they are pulsing and radiating through the boat wiring harness.

Given the relatively slow rise time of AM signals, ferrite choke, a coil and a capacitor may all be required. A ferrite core may not resist the pulsing enough by itself at such low frequencies.

I wonder if higher quality LED lights have this filtering built in? Wonder why, given how radio signals such as DF are used as navigation, wonder why the coast guard hasn't set standards on spurious radiation of these devices?

 

[Maine Sail]

That cures conducted noise but not radiated noise. The last poster has it correct. Many LEDs are notorious sources of RF radiated noise.

Bingo!

Folks often wonder why quality LED running or interior lights (ABYC A-16 or USCG certified compliant) cost so much....

 

[Don S/V ILLusion]

Trivial? Perhaps some LEDs don't save much, but mine use one tenth the amount of energy and this means I don't have to run the generator as much to recharge batteries. Some of the places I go, getting diesel or gas is "difficult"....

Worth it? Well, guess that has be be evaluated by each individual in their circumstance, but, I have noticed a minor problem with AM, even my battery powered radio, so no power cord to put Ferrite on. But, I might try some ferrite cores and twist the wires around them at each fixture. I'll bet, now that I think about it, they are pulsing and radiating through the boat wiring harness.

Given the relatively slow rise time of AM signals, ferrite choke, a coil and a capacitor may all be required. A ferrite core may not resist the pulsing enough by itself at such low frequencies.

I wonder if higher quality LED lights have this filtering built in? Wonder why, given how radio signals such as DF are used as navigation, wonder why the coast guard hasn't set standards on spurious radiation of these devices?

The FCC, not the CG, is the responsible regulatory agency for the 'airways' and they have set stringent requirements for emissions from LEDs. Unfortunately, many of the bulbs sold in big box stores don't comply with the requirements resulting in a number of administrative enforcement actions.

Once again, capacitors and ferrite chokes are useful for conducted noise ONLY. The issue here is radiated noise from LEDs for which they are useless.

As to the value of LEDs in managing energy requirements, saying they use "one tenth the energy..." Ignores the typical duty cycle of interior or running lights. About the best thing to be said for LEDs is that they don't attract bugs.

 

[Fred]

Ken... You are correct about dimmers, I missed the part about navigation lights. In any case the RFI emissions of the LEDs is usually due to the switching drive circuits that are used which are similar in nature to a dimming circuit with the same possibility for RFI emissions if not properly designed or filtered.

I suspect that some cheaper, unregulated LED bulbs simply use dropping resistors rather than regulation circuits and would not have the same issue. I don't have enough experience with these bulbs to know for sure.

 

[shanker]

All my LED's were purchase from marinebeam.com. I read that they had best product and so I purchased through them and paid significantly more than I could have through other on line LED vendors. I will test them this weekend by reinstalling the original bulbs to see what happens.

 

[JamesG161]

My suggestion is get a better radio. There are two many causes for AM interference. Nature or LED's usually don't FM. Most good radios have antennae and power supply noise filters.
Jim...