I have 5 identical light fixtures (2-40 watt tubes with electronic ballast) in my garage, 3 of them broadcast AM strongly (strong engough to interfere with car radios in front of my house) 2 of are silent. I have compared the wiring of all of them and they are identical. On one of the noisy ones I redid all of the connections, made sure the ground lug on the case was bare metal and added a ground wire to the ballast. Result - no change.
If only one tube is installed the light makes no noise, with two it screams. The source of the noise seems to be the wires between the ballast and the tubes and the tubes themselves.
I am getting ready to try an input filter (corcom type) and some beads on those wires.
Any other suggestions? I'm really tired of having a dark shop. I can't just return them because I have had them almost a year now.

What if you change the lengths of the wires, to change the frequency of the antenna that it's "broadcasting" with?

Same issues!

I changed some of my old fluorescent’s over to new electronic ballasts (and the correct thin tubes) and every time I turn them on I get big static over the FM.
Changing antenna wires didn't help.

I'm about to run a cable to the shop to hook up the satellite.

for listening in the garage, see if your favorite station is streaming on line,
(I get KCRW that way) and pump that into the garage.
Is the interference on the portable radios (battery powered) and those plugged into the wall the same?
Bad radio reception drives me absolutely nuts!!!

Just fixing MY radio reception won't do - I'm broadcasting to my neighbors also.

QUOTE (Dead Air @ Dec 27 2005, 06:41 PM)

for listening in the garage, see if your favorite station is streaming on line, (I get KCRW that way) and pump that into the garage. Is the interference on the portable radios (battery powered) and those plugged into the wall the same? Bad radio reception drives me absolutely nuts!!!

Ya...right! I'm in the country remember!

Crappy dial-up

Born to be.....loading...loading....wild.....loading...loading

After doing a bit of google on the subject it seems that you either need to replace the light fixture...or get a filter.

filters can be had a radio shack...or equivelent, and the new fixtures can be had at home depot...

Everything I read said that flourecent lights and neon lights cause radio interference..period...

The problem is that these types of lights are working based upon arcing electrical current through the gas constantly..this makes for the interference...

rich

I just installed an input filter and shielded the feed wires to the tubes and very thoughly grounded everything including the cover that was totally isolated with paint. It helps but does not eleminate the problem. The tubes are still radiating RFI - I can move my hands across the tubes and hear the interference change. The only thing left is ferrrite beads and a cap arcross the feed wires. At least now my neighbors should not be having interference from my lights.
These type of ballasts in my new lights run the tubes somewhere between 25Khz. and 80Khz. Unfortunatly the DOE has banned the sale of the old magnetic ballast light fixtures and the new style pollute the AM waves. Somehow the FCC thinks this is just fine and approves of this type of light even thought it interfers with the emergency broadcast system (just heard a flood warning a little bit ago)

EMI or Electromagnetic Interference.
We have guys with Phd's working through all the problems associatedwith building ships. Anyway most of what they do is shielded cables that attach to good grounds. You might want to spring for lighting that was built within the last 10 years with electronic ballast.

QUOTE (Joe Ricard @ Dec 27 2005, 07:43 PM)

EMI  or Electromagnetic Interference. We have guys with Phd's working through all the problems associatedwith building ships.  Anyway most of what they do is shielded cables that attach to good grounds.    You might want to spring for lighting that was built  within the last 10 years with electronic ballast.

The lighting IS NEW that's the problem, the good ol' magnetic ballasts didn't have this type of problem - they just hummed and used a few more watts. These new ones spew RF at 25-80KHz. Grounding helps some but I am thinking the real solution is an RF screen over the tubes. Time to get out the oscope (and remember how to use it) and see what is going on.

Switching power supplies are great for efficiency (and weight, size, etc.) but really can trash the AM radio band. I've noticed that driving around town and listening to AM (not so much anymore now that I have XM) that when I stop at intersections I often pick up a lot of interference off the newer LED traffic lights. That's not due to the LEDs but the noisy switchers powering them. I don't know what interference limits they put on fluorescent lights, but I do know computer equipment and we only measure conducted EMI from 150 kHz up to 30 MHz. Radiated EMI is measured from 30 MHz on up. So the manufacturers of lighting equipment probably have it easy and can get away selling really noisy equipment. The Corcom filter might help on the AC leads, make sure the filter can is well grounded to the light fixture and keep the leads separated (the noisy side from the quiet side). Having the AC power running through conduit may help but not an easy thing to do with existing house wiring. Ferrites usually won't touch noise in the AM band, the frequency is too low for them to be effective. You can twist the leads to the fluorescent tubes, or twist a grounded wire in with them to add capacitance. Better yet is to slip some shielding braid over them and ground it. Or use metal duct tape to tape the wires against the fixture sheet metal. If it's coming off the lamp tubes themselves then you'll have to play around with some window screen or something. Too much metal around the lamps might mess up the operation of the lights as well as reduce the light output. Good luck!

QUOTE (914GT @ Dec 27 2005, 09:04 PM)

Switching power supplies are great for efficiency (and weight, size, etc.) but really can trash the AM radio band. I've noticed that driving around town and listening to AM (not so much anymore now that I have XM) that when I stop at intersections I often pick up a lot of interference off the newer LED traffic lights. That's not due to the LEDs but the noisy  switchers powering them. I don't know what interference limits they put on fluorescent lights, but I do know computer equipment and we only measure conducted EMI from 150 kHz up to 30 MHz.  Radiated EMI is measured from 30 MHz on up.  So the manufacturers of lighting equipment  probably have it easy and can get away selling really noisy equipment.  The Corcom filter might help on the AC leads, make sure the filter can is well grounded to the light fixture and keep the leads separated (the noisy side from the quiet side).  Having the AC power running through conduit may help but not an easy thing to do with existing house wiring. Ferrites usually won't touch noise in the AM band, the frequency is too low for them to be effective. You can twist the leads to the fluorescent tubes, or twist a grounded wire in with them to add capacitance. Better yet is to slip some shielding braid over them and ground it. Or use metal duct tape to tape the wires against the fixture sheet metal. If it's coming off the lamp tubes themselves then you'll have to play around with some window screen or something. Too much metal around the lamps might mess up the operation of the lights as well as reduce the light output. Good luck!

Thanks for the info. I pretty much did everything you suggested earlier this evening. Well grounded input filter, shielded all of the "output" wires to the tubes with shielding braid (grounded one end only), kept the AC wires as separate from the tube wires and sealed up everything ground wise. The AC end is now clean so I get the fun job of 4 more fixture rebuilds and then play with some grounded screen over the tubes. At least I will finally have light instead of the old dim bulb I've had the last 3 years.

Check the supply voltage to the balast, if it is low due to poor connection (damn wire nuts) or whatever it will make all kinds of noise (RF).

We had a camera man who used dimmers on everything, he couldnt figure out why some lights caused his wireless to not work. . .

I finally fixed it. I found out that Home Depot still sells the good old magnetic ballast shop lights. I bought one and tested it for RFI and it was nice and quiet so I got a bunch of them along with some nice full spectrum bulbs and lit the heck out of my garage - I have up to 9 of them in my small garage. Very nice having tons of light and no shadows.

Unfortunately, the newer style electronic ballasts generate harmonics that feeds noise (garbage superimposed back on the 60 cycle sine wave) back into the system. It creats havoic in offices with computers and sometimes at home too. You found the answer. Old fashion electro-magnetic ballasts. I personally am not a fan of electronic ballasts. Another option is putting the fluorescents on a dedicated circuit. I chase these problems all the time. Eddy