# flourescent rf interference



## dogleg (Dec 22, 2008)

I have a customer that brought to my attention that the flourescent lights (4' 4 t8 bullb electronic ballast wraps x 4 lights)are causing interference on the radio when he trys to play it and the lights are on.Is there a filter or anything that can be done to correct this problem?


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## Speedskater (Oct 2, 2009)

Probably not, over on the HAM forum they talk about selecting quite fixtures or swapping ballasts.


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## mbednarik (Oct 10, 2011)

I have a customer that called me with the same problem. Except his radio worked just fine until about a week ago. He noticed that all of the interference came when he turned on his front office lights. I disconnected each light one by one and one ballast was causing the trouble. The same brand and type as the 5 others in the same room. Replaced the one and he was back to listening to rush. Lol. I don't know what happened to that particular ballast, but it started fine, was not hot to the touch or different from the others except for the interference.


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## KennethKyle (Dec 21, 2012)

The ballasts in most fluorescents emit electromagnetic radiation called RFI. Ur higher quality fixtures do not. see if it is on the same circuit as the lights but increasing the clearance between the radio and the lights should work. and last resort break out the aluminum foil and let's boost that signal


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## Vintage Sounds (Oct 23, 2009)

mbednarik said:


> Replaced the one and he was back to listening to *rush*. Lol.


In that case I would have left the defective ballast in place and told him the interference was an unfortunate fact of life. :thumbsup:


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## mbednarik (Oct 10, 2011)

Vintage Sounds said:


> In that case I would have left the defective ballast in place and told him the interference was an unfortunate fact of life. :thumbsup:


I thought about it, but he is also my ins agent, a good one to keep happy, rush or otherwise.


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## gnuuser (Jan 13, 2013)

while the ballast does in fact emit emf it is not enough to cause radio interference.
what is causing that is the plasma arc in the tube. 

A fluorescent lamp is an electric light powered by standard household current. Instead of making a hot wire glow, as with an incandescent lamp, an electric current makes a gas glow. Glow from the gas is strong enough to serve as an efficient light source. A fluorescent bulb contains a vacuum into which a small amount of mercury is introduced. The liquid mercury evaporates in the vacuum, forming a thin vapor.The light starts with a brief high-voltage pulse that makes the mercury vapor conduct electricity in a condition called a plasma. After the pulse, the voltage drops to a nominal 110 V.


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## hardworkingstiff (Jan 22, 2007)

*mbednarik*



gnuuser said:


> while the ballast does in fact emit emf it is not enough to cause radio interference.
> what is causing that is the plasma arc in the tube.


mbednarik, please confirm whether or not you changed just the ballast or the ballast and the lamps.


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## mbednarik (Oct 10, 2011)

hardworkingstiff said:


> mbednarik, please confirm whether or not you changed just the ballast or the ballast and the lamps.


Ballast only.


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## dogleg (Dec 22, 2008)

We've been busy with other projects ,this is a garage/hobby woodshop for a summer cabin so it is not on the top of the list ,however when I get back to it next week or so I will try disconnecting one light at a time to see if it is an individual ballast or all of them.I will try replacing the ballast or ballasts until the interference stops.PITA !Thanks for the info and I will welcome any other ideas.


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## macmikeman (Jan 23, 2007)

dogleg said:


> We've been busy with other projects ,this is a garage/hobby woodshop for a summer cabin so it is not on the top of the list ,however when I get back to it next week or so I will try disconnecting one light at a time to see if it is an individual ballast or all of them.I will try replacing the ballast or ballasts until the interference stops.PITA !Thanks for the info and I will welcome any other ideas.


http://www.ccrane.com/antennas/am-antennas/

And this: http://www.ccrane.com/radios/wifi-radios/


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## Electric_Light (Apr 6, 2010)

gnuuser said:


> while the ballast does in fact emit emf it is not enough to cause radio interference.
> what is causing that is the plasma arc in the tube.


Ballasts do produce interference. The question is how much. Residential use ballasts are held to more stringent standards, which means for home use, ballast must be rated FCC part B.


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## Peewee0413 (Oct 18, 2012)

They make suppression filters. Its probably in the wiring not electromagnetic radiation.


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## Cletis (Aug 20, 2010)

I'd try installing a few toroids on the line side and see what happens


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## Cletis (Aug 20, 2010)

I would suggest something like this

http://www.mag-inc.com/products/powder-cores/high-flux-cores


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## hardworkingstiff (Jan 22, 2007)

Do you think a gauss meter could locate the offending ballast or lamp?


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## Peewee0413 (Oct 18, 2012)

I think its a bad ballast. I have 14 fl. Lights in my shop it doesn't mess with the radio. Now the drill causes interference. Check the current and voltage off each ballast maybe it'll be obvious. Probably not, but its cheaper than buying a gauss meter lol.


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## wendon (Sep 27, 2010)

Just curious if maybe the electronic ballasts give off more noise than the old magnetic ones. We replaced a bunch of fluorescents in a church with new T8's and now the wireless units for the hearing impaired give off a loud crackling noise!!! Tried all kinds of things but still haven't fixed it!


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## Peewee0413 (Oct 18, 2012)

I think electronic ballast are solid state. I don't know if it gives off any more. Probably equal or less.


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## retiredsparktech (Mar 8, 2011)

Peewee0413 said:


> I think electronic ballast are solid state. I don't know if it gives off any more. Probably equal or less.


 I collect and repair old radios. In various thrift shops that have electronic ballasts, radios will not receive anything on FM and very little on AM.
It used to be just the opposite. I think they create harmonics of the operating frequency. Electronic ballasts convert 60HZ to about 25KHZ.


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## Cletis (Aug 20, 2010)

retiredsparktech said:


> I collect and repair old radios. In various thrift shops that have electronic ballasts, radios will not receive anything on FM and very little on AM.
> It used to be just the opposite. I think they create harmonics of the operating frequency. Electronic ballasts convert 60HZ to about 25KHZ.


Actually 25khz- 60khz nowadays, lots of options


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## retiredsparktech (Mar 8, 2011)

Cletis said:


> Actually 25khz- 60khz nowadays, lots of options


 I was going back about 25 years, when I inquired about early electronic ballast failures. :blink:


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## aftershockews (Dec 22, 2012)

We installed a new row of florescent lights at a small clothing store. This store had a security bar at the door for theft purposes. New lights would cause it to go off at random.


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## FanelliBT (Dec 14, 2012)

I have seen flouresent lights and CFLs on the same circuit screw with A/V equipment. One of my coworkers has a projector in his house and the 4' T8 in the basement ( on the same circuit ) throws static on the screen. Have seen it with radios as well. Might want to check to see if it is the same circuit if it is a plug in radio.
-Ben


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