R/F Interference

[Mosey]

I recently replaced a 100 watt linear incandescant light bulb with an 21 LED tube. Brilliant (no pun intended). However, maybe not so brilliant, as the new lamp emits radio frequency interference that makes listening to the FM radio impossible. AMSCO, the maker of the lamp isn't interested in the problem ("you are the only one who complained"). These lamps are $100 bucks a pop! Does anyone know how to filter or choke off the R/F?

 

[steamer]

Are you sure it's the bulb? They should conform to a modicum of RF testing for interference. Are they CE marked?

Check to make sure you don't have a bit of bad wiring...a small arc will transmit RF over the whole spectrum....How we used to get the guys upstairs in the college dorm to turn down the stereo.... ;D

Dave

 

[bezalel2000]

Hi Mosey

Do you have a link to an example in a shop on-line so we can see the specs.

I'm not able to work out why an LED device would be producing RF

LEDs are a DC device (infact a rectifier-which means they convert AC voltage to DC voltage.)
it gives little value to drive them with an RF switching supply. (the usual source of RF)
such as is used in a fluorescent device that needs typically more than 150VAC to strike.

Bez

 

[n4zou]

If you are lucky the power supply is separate from the circuit board the LED's are mounted on. If that's the case you can use ferrite snap beads on the wires going into that power supply and coming out of it before they connect to the LED strip. Here is a link where they can be purchased at reasonable cost.
http://www.allelectronics.com/index.php?page=seek&id[m]=pattern&id[q]=FERRITE+&x=25&y=8

If the power supply is mounted on the same strip as the LED's you'll need to do surgery on it. If you have experience soldering small parts you may be able to install some tiny ferrite beads on the board. Noting having it in front of me means I can't tell you what you'll need. Mouser.com has over 5,000 EFI/RFI components to select from so you can deal with the interference problem.
http://www.mouser.com/Passive-Compo...rs-Ferrites/_/N-194jj?Keyword=ferrite&FS=True

You really should not have this problem. Considering the manufacturer blew you off instead of taking the appropriate and required action to deal with the interference problem I would call them again and request a replacement as your product is defective and if they refuse, file a complaint with the FCC.
You can file a complaint at this link.
http://www.fcc.gov/guides/interference-defining-source

The very last thing the manufacturer wants is an FCC investigation over EMI/RFI emitted by their product. they could end up with a 100% recall which would quite possibly put them out of business.

 

[n4zou]

Hi Mosey

Do you have a link to an example in a shop on-line so we can see the specs.

I'm not able to work out why an LED device would be producing RF

LEDs are a DC device (infact a rectifier-which means they convert AC voltage to DC voltage.)
it gives little value to drive them with an RF switching supply. (the usual source of RF)
such as is used in a fluorescent device that needs typically more than 150VAC to strike.

Bez

LED power supplies incorporate pulse modulation to reduce power consumption while still producing the same lumen output.

 

[bearcar1]

Hi Mosey, that suspect new bulb arrangement, was it manufactured in the US with a UL listing? (my guess is probably not or the power supply is of questionable origin) Something is definitely amiss to interfere up into the FM band.

BC1
Jim

 

[Mosey]

The exact info is the lamps are "Linestra", made by AAmsco, in Summerville, SC. They are 11 watt LED, and UL listed. They are designed to be an exact replacement for their 150 watt linear incandescant Alinea bulb. I have no more info, but take a look at www.Aamsco.com/Linestra/AlineaLED.
I think I will bring this back to them for further consideration. There is absolutely no question that the lamp is the source of interference with FM radio in the space.
When I hear from them, I will see where I need to go with the ferrite bead concept. That seems to bring back distant memories of making radios in the 50's (the ones with tubes).
Once again, and to no surprise, the knowledge on this forum is extensive, valuable and given generously. Thank you.

 

[n4zou]

Are you using a dimmer with your light? I went to the site and noticed a standard dimmer for incandescent lamps could be used. That device could very well be the source of the problem. They are notorious for producing RFI when they get old. *I went around my neighbourhood replacing them for free when they started making noise. If you are using a dimmer try taking it out and bypassing it and see if the RFI interference goes away. It's very possible the dimmer worked just fine with the incandescent lamp but it's **** the bed with the new LED light.

*At that time I was operating one of many Ham Radio stations that provided ground to space amateur e-mail services for the Russian MIR Space Station. As it would fly over the ground stations would connect and upload/download messages to and from it. We only had a 10 minute window to upload and download messages at 1,200 baud. Our ground based digital packet system would chop up the data and pass it along keeping up with the MIR Space Station as it passed the many ground stations. We successfully send and received huge amounts of data under these severe restrictions. Any RFI interference would kill the signal from the MIR thus wiping out a ground station.

This link is now an archive of Amateur Radio communications with the MIR Space Station.
http://www.tcoek12.org/~tcarc/mirtv.html

The ISS (International Space Station) has very limited interaction with Ham Radio. It's a highly coordinated affair limited to voice communications with American school students and selected Ham Radio operators that also are employed by NASA. With the MIR Ham Radio operations developed real applications for communication and deployed them successfully. The ISS is just simple propaganda programming for the network media outlets.

 

[Mosey]

No dimmers.

 

[Troutsqueezer]

It will be hit or miss with the beads, probably miss. I'd take the unit back. You can get one for around 35 bucks at Lowes.

 

[jct842]

I looked at the web site.....thats a high dollar designer light! I think if the manufacturer refuses to talk then the only recourse is the FCC. I don't think I would mess with beads or any other maybe fix...if they made it they can fix it or do a refund. john

 

[bezalel2000]

LED power supplies incorporate pulse modulation to reduce power consumption while still producing the same lumen output.

Thanks N4

Of course *club* what was I thinking :wall:

I'll just wind the brain forward 60 years (and into the 21st century)

I must have been thinking of the LEDs that were all the rage in the 1940s

you know the mercury vapor type ;D


Embarrassed Bez

:hDe:

 

[Mosey]

Bez,
There are no embarrassments on this forum. Thanks for trying.
Mosey

 

[Lakc]

LED power supplies incorporate pulse modulation to reduce power consumption while still producing the same lumen output.

That was a new one to me. Thanks! Strange that would be emitting so far up in frequency.

You can scavenge the RFI filter off a blown computer power supply, its the two coils and capacitor right where the power cord attaches, soldered to the plug itself. Running power to the light through that filter may help, as I suspect its using the entire house wiring as an antenna.

Ferrite beads can do the job, but they are very frequency and design sensitive, so random success is not very common.

 

[Mosey]

Yes, you seem to be right on the beam. The house wiring must be the transmitter antenna, as it disturbs all of the FM radios in the house when you flip that switch. I will try to get Aamsco to take ownership of their problem, but look for some RFI filters. Maybe they would find this post interesting reading in the Board Room?