:How come I get major static on my am tube radio when I turn on the flourscent lights in my garage. What gan I do to remove that. There also is a slight modulation hum in the speaker, especially then the volume is cranked up.
Flourescent lights generate noise in AM radios. You can put a cap across the AC line which will help but won't entirely eliminate static interference. Some of this noise will come directly from the lamps.
Best to turn off flourescent lamps while listening to a radio. Grounded aluminum window screen over the lamps will reduce interference.
Norm
:Not sure about the ballast. All I know is they are 8' bulb units.
My electronics workbench is in the basement of the house. In that basement, I have (I just counted them): 7 fluorescent fixtures (each with two tubes) and 8 compact fluorescent lamps (the screw-in-type lamps).
I've probably played 50+ different AM radios of all types and shapes at my bench, with no noticable RFI from the fluorescent lamps. I have installed no RFI filters or capacitors anywhere on these lamps or at the 120-V recepticles serving my bench.
Three of the fluorescent fixtures and one CFL are almost smack-dab over my bench, and they are always "on" when I'm testing radios.
I will say, however, that only two of the fluorescent fixtures are on the same 120-V branch circuit as my radio bench power strip.
All of my fluorescent fixtures are standard F40s with magnetic ballasts. I don't know about the CFLs, but assume they are electronic ballasts.
My basement is open for your testing! Bring your own radios and contact me in advance for an appointment. Unfortunately, they're not making any new episodes of "Twilight Zone," so that isn't a possibility.
:Hi John
:
: Flourescent lights generate noise in AM radios. You can put a cap across the AC line which will help but won't entirely eliminate static interference. Some of this noise will come directly from the lamps.
:
: Best to turn off flourescent lamps while listening to a radio. Grounded aluminum window screen over the lamps will reduce interference.
:
:Norm
:
:
::Not sure about the ballast. All I know is they are 8' bulb units.
Keep in mind that if you put a filter on the radio, you may significantly reduce its sensitivity, since radios use the line cord as a source of reception (earth). You may be better off with the chokes on the fluoresent than on the radio. If you do put them on the radio, and notice a reduction in reception, make an alternative ground to a water pipe.
T.,
I wish it was that easy. My flourescent light interference is broad, across the band.
It would be interesting to know why Doug's lights don't cause interference? Do they have built in line filters? Would expect some noise to radiate from the lamps.
Here is something interesting. Operating some radios under flourscent lights causes hum. Lamps are actually turning on and off at a 60 cycle rate. This can modulate the detector tube causing hum. I've noticed this mostly on 1920's battery radios.
Norm
:Someone told me that these units could produce around 400khz RF. If thats the case, its close to the IF's and the line cord would not be an issue. Now wouldnt the isolation transformer take some or most of the line noise out.
I also have one of thse compact flourcestent light bulb thingies about 4 feet away in the laundry area that's always on 24/7 ... no problem..
However a few weeks ago I was getting ear-splitting RF noise that was killing ALL reception.
... It turned out to be that compact flouescent bulb thing getting weak and going bad.
.. swapped in a new one and good to go again... no noise... from the new one.
Regarding isolation transformers, and transformers in general, they can help if they have an electrostatic shield built into them. This is a band of copper that is between the primary winding and the rest of the windings.
The solid state fluorescent fixtures do produce more interference than the traditional kind. With most of my radios I get almost no disturbance from the traditional kind. In all cases, deteriorating fluorescent tubes cause static. It is wise to replace deteriorating fluorescent tubes for several reasons. For one, they cause static. For another, they don't give off as much light. For a third, etc., the ballast works harder to keep them running, which stresses it out, consumes more electricity, and can be a potential fire hazard. While not a frequent occurance, I have seen bogged down ballasts blow tar out the side and smoke like crazy. Some ballasts do this even when properly taken care of (which is rare....who replaces their fluorescents before they go bad?). Those ballasts are cheap. The better ones should last you many years if you replace the tubes as soon as they start flickering or get dim. This flickering is accompanied by blackening of the ends. Sometimes new tubes flicker, too. As they are run, the gas inside mixes, or whatever it does, and the flicker slowly migrates to the center and eventually disappears. Cold tubes flicker, too, and should not be considered faulty.
T.
Here's some ballast info regarding electromagnetic noise:
""Ballast cases and fixtures must always be grounded. The
ballast case may be grounded to the fixture or otherwise
grounded. It could be hazardous to make contact with an
ungrounded fixture or ballast when in operation. Neglecting to
properly ground the ballast and fixture combination may also
result in failure of certain lamps to start or for unacceptable
levels of electromagnetic noise to be conducted onto the
power lines.""
In commercial offices or where lighting is specified by an architect, etc., electronic ballasts will usually be specified. But when I go to Home Depot and get a cheapo 2-tube, 48" fluorescent fixture, it will always have a magnetic ballast -- their initial cost is less than electronic.
Yes, you can buy replacement ballasts, but they need to be sized to match the wattage and number of tubes in the fixture.
Nowadays, most all fluorescents are rapid start. Years ago, they used starters -- little cans with switches that cut out the lamp's heaters once the lamp started.
:Someone told me that these units could produce around 400khz RF. If thats the case, its close to the IF's and the line cord would not be an issue. Now wouldnt the isolation transformer take some or most of the line noise out.