Can Anyone Explain This?

[Turkeytop]

These warm, summer evenings I always stay outside on the patio until after dark. I sit at the patio table under the patio umbrella with my radio.

The umbrella has solar powered LED lights running along each of the ribs. These mid-summer nights, the lights always turn on about 9:15 PM. The very instant they switch on, it somehow attenuates the signal to my radio. A weak station gets weaker and sometimes gets lost altogether.

Anyone have a theory as to how that happens?

[Ben Zonia]

Does it make a noise in the radio? Or more noise? Do you notice a strong signal without modulation on a specific frequency?

Otherwise, I'm thinking there is a very strong RF signal desensitizing the radio way off frequency.

Do all radios behave similarly, or just that one? What kind of radio is it?

[Turkeytop]

The noise is just that sort of white noise you get when the FM signal is weak. Sometimes I can improve it by manipulating the whip antenna, but not always. It's just a Grundig portable AM/FM radio. Tomorrow I'll try it with a different radio.

[k8jd]

Those LED light strings are notorious for the power supply regulators, (and maybe the LED junctions) generating RFI! Maybe replacing the solar power supply module , or adding a ferrite RF supressor to the wire where it leaves the module... MAY Help.
Good luck.

[Turkeytop]

Tried it tonight with a different radio and didn't experience that same problem. I think it's because tonight's radio was a more sensitive receiver and can process the weaker signals OK.

It doesn't seem like the lights are emitting any RF noise. It seems more like, when the circuit is active, it has some kind of shielding effect.

[k8jd]

Can you disconnect or diable the LED lighting? Then Test radios without the Lighting running ?
It sounds like the noise is wide band and strong enough to desense one radio design.

[Turkeytop]

Can you disconnect or diable the LED lighting? Then Test radios without the Lighting running ?
It sounds like the noise is wide band and strong enough to desense one radio design.

The lighting is disabled until the darkness triggers it. The effect is immediate.

[k8jd]

Actually there is a charging regulator circuit between the solar cells and the bettery that operates the lights...THAT could even be generating the wideband RF interference !! There is always something running even when the lights are off.

[Turkeytop]

So, I tried it again tonight using my Sangean ATS 909. It has a signal strength indicator. I wanted to see if the signal level changed when the lights turned on. I didn't. Also the quality of the signal wasn't effected using that radio.

[cckadlec]

LED lights are horrible for FM! I would drive by a gas station on the way to work every day and whether it was their gas station sign lit up or LED lights outside/inside the store, it would wipe out almost the whole FM band for about a distance of two blocks only after dark. And people who use those kinds of things in apartments have the same effect. Almost all FM signals are wiped out in the entire apartment complex due to one person using whatever they use. Best of luck, because this kind of thing will probably not be resolved.

[Turkeytop]

Most of the lighting in our house is LED and doesn't cause any problem. Except for one shop light in the basement that I have to keep turned off most of the time. It completely wipes out the MW band and sections of the SW bands.

[HD74]

Obviously capacitative flatulence. Do you smell anything bad after the lights activate? I would recommend a Little Trees flatulence cleaner.

[k8jd]

The voltage converter in the base of LED replacements seem to have some filtering for RFI . Some older ones did not. The small LED strings have wall-wart voltage supplies that have RFI problems.
IF you think FM is bad, try listening on AM or Short wave bands !!!!!AWFUL RFI ! FROM LED LAMPS.

[MotorCityRadioFreak]

You are eliminating RFI when they go off. Simple as that.