Posted: 11/6/2012 6:23:40 AM EDT
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I've been fighting a RFI issue for a long time.
There's three each, 4 T8 light fixtures in the garage/ham shack and another three fixtures in the carport. All six are of this model. Whenever any of them are on I may as well shut down the radio. S7 to S9 noise more noticeable on the lower bands but the upper bands are affected also. 2m is also affected as reports say there is a hum in the audio. Turning off the lights drops the noise on HF to S3 or whatever the local conditions are and the 2m hum is gone. So the lights are creating RFI. How do I get rid of it? Dug around the net and the ARRL RFI book and came up empty. I've resorted to turning off the lights and running an undercounter light at the operating position. Not the best solution by far. I'm tired of operating in the near dark. Then I found some info concerning flourescent ballasts. Seems there are two ratings. Commercial and residential. The difference I care about is that residential rated ballasts have a lower RFI emission standard than commercial rated ballasts. Hmmm. Popped the covers off of the carport lights and one had a residential ballast and the other two had commercial ballasts. I remember replacing a ballast a while back and it was that one with the residential ballast. Obviously the lights I put up had commercial ballasts as OEM equipment. So a trip to the big box store and picked up a couple replacement residential rated ballasts. Replaced them yesterday and fired up the Marconi to see if it did any good. Man what a big difference. Carport lights on or off I couldn't tell a difference in the S meter noise level. The garage lights still have the OEM ballasts and turning those lights on bumped the noise from S3 to S7. Going back to the big box store and picking up 3 more ballasts today to see if I can at least reduce the RFI from the garage lights. Will post back with the results. Take home message: If you have flourescent fixtures creating RFI, see if you have a commercial ballast. If you have a commercial rated ballast replace it with a residential rated ballast. When shopping for flourescent fixtures make sure you only purchase those with residential rated ballasts. |
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Followup on the flourescent light RFI issue.
Went to the big box store and picked up three more residential rated ballasts for the garage/ham shack. Prior to any work I fired up the Marconi and got everything online like I was going to operate. Checked the noise level on 7.230 and it was S5 with the garage lights off and S7 with the lights on. Inline with what I've seen previously. Swapped out the ballasts. Checked the noise level and ... no change. Yup. Fail. Checked a couple of other bands and what I did see was one S unit change if at all. 40m has always been troublesome with the lights on. So maybe it has made a slight improvement. Best as I can figger is that the garage lights are far enough away from the antennas that it's not affecting those. However I'm guessing that whatever RFI that is being created is already in the shack and whatever I do it isn't going away. All is not lost. Replacing those ballasts in the carport which is 8 to 10 feet from the antennas made a huge difference. All I'm out in the garage is $60 and an hours time. Oh well. Will investigate that filter thingy mentioned above. Also looking into alternative lighting such as LEDs. Sticker shock to say the least. May have to bite the bullet and go with old school ceiling light bulbs. But will try the filter thingy first. Wife is rolling her eyes but I'm having fun figuring this stuff out. |
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I'm guessing that whatever RFI that is being created is already in the shack and whatever I do it isn't going away. If you've got a portable AM radio, you might try turning it to a spot on the band where you can hear the noise, and then start moving it around your house to see where the noise gets loudest. Flipping breakers off and unplugging AC-powered devices one-by-one can also help track it down. May have to bite the bullet and go with old school ceiling light bulbs.
Some of the CF bulbs are pretty RF-quiet, even though they use electronic ballasts. They're also cheap, easy to replace, and easy to mount wherever the light is needed most. |
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Have the CFL ceiling light bulbs in the kitchen. About the same distance to the attic antennas. I never know when they are on or off. They are that quiet. And they are the cheap ass bulbs from the big box store.
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May have to bite the bullet and go with old school ceiling light bulbs. Some of the CF bulbs are pretty RF-quiet, even though they use electronic ballasts. They're also cheap, easy to replace, and easy to mount wherever the light is needed most. Think that may be the ticket. Keep a couple of the T8 fixtures when I really need the light like when reloading or other projects. Install two or four recessed ceiling lights using CFLs for light when I'm hamming. No big thing to wire it in. Might have a little RFI but at this point I'm scratching for every half S-unit I can get. Big RFI producer in the beginning was a couple of touch lamps. My RF smoked those within the first month on HF. One way to get rid of them. |