CFL RFI gone

Discussion in 'General Technical Questions and Answers' started by N3PM, Jul 8, 2020.

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  1. N3PM

    N3PM Ham Member QRZ Page

    Started getting nasty on and off RFI last winter. It started at 1.3 or so mHz, and dropped by 5 mHz, but still in the background, and not linked with day/nite or any particular time. Couldn't connect the dots with anything I had control over or access to. I saw my neighbor's post light on today, and the noise was there. He knows I have "short wave radios " and was open to my concern. A demo with a portable radio, one LED bulb and the problem was fixed. The CFL was a few years old, but I suppose they get noisy after a while. Just one more thing ya can check.
    Mike N3PM
    K2XT, K8PG, NQ8J and 1 other person like this.
  2. KB0MNM

    KB0MNM Ham Member QRZ Page

    Yes, and here is more of what I usually post when someone mentions CFL or LED as a source of interference ( this has been around for a while ):

    Radio Interference from LED Lighting Systems

    NPSTC has been following the issue of interference caused from some LED and fluorescent light system ballasts, which have disrupted both public safety communications and cellular wireless systems. We have also been informed that some USB3 powered computer hubs will cause interference to public safety portable radios operating in the 700 MHz band. NPSTC will publish a formal survey on this topic in early November.

    Currently, NPSTC is working with the American Radio Relay League (ARRL) to learn more about the extent of this problem. ARRL has been doing extensive research and testing into different problems and scenarios. In 2013, the FCC issued an order directing General Electric (GE) to make some changes to their LED lighting transformers after complaints were received about interference.

    PC World also has a story about night time interference in Los Angeles when a 41-story office building turns on its lights, which creates RF noise that drowns out a nearby Verizon Wireless tower.

    Other noise-makers are certain inexpensive switch-mode power supplies, neon signs, and lately 'grow lights' used for that 'wacky weed' and other projects.

    And while I have your attention, frozen ground makes for a less effective electrical ground- which is why most rods are 8 ft. long ( to get below the frost line ). The signal to noise ratio can change based upon ground conductivity- also linked to water and minerals.
  3. KF5LJW

    KF5LJW Ham Member QRZ Page

    Mike it was likely the ballast going bad. However, overall CFL's tend to be quieter then LED's which are notorious to having very noisy electronic drivers. Ironically it is called Progress by the Green Mafia as I call them. Not so many years ago ballast were magnetic operating at 60-Hz to provide the required electrical isolation between input and output. Otherwise if there were an internal fault the user is not exposed to the utility. Those days are gone for most products. Magnetic is not efficient or politically correct today. We now have have more efficient, less expensive, smaller, and lighter devices. Unfortunately RFI is not much of a concern anymore. It would take 30-cents more in materials, and an extra months to design and test an effective RFI filter. Just enough to satisfy FCC which aint saying much or enforced.

    Congrats on finding it. I do quite of bit of RFI investigation work and have literally $100K worth of equipment to find it. The easiest, most used, fastest, accurate and most reliable piece of test equipment I use is an old Transistor Radio, AM only tuned to an unused channel frequency as low in frequency I can find. My peers use good ole Walkmans with earphones. Second most used piece of equipment is my fingers to turn circuit breakers off.
    W1PEP likes this.
  4. N3PM

    N3PM Ham Member QRZ Page

    Thanks Dereck. I've tracked a few cases with just an AM portable. I didn't think of the ballast going south. The LED bulb was from a Lowes package I bought a few years ago. I tried one back then and it was quiet. I do get a kick out of "Name that Noise" games!! Like, can you name that noise in 5 seconds of audio?
    I gain a lot of info reading about other's findings.
    Mike N3PM
  5. N3PM

    N3PM Ham Member QRZ Page

    "And while I have your attention, frozen ground makes for a less effective electrical ground- which is why most rods are 8 ft. long ( to get below the frost line ). The signal to noise ratio can change based upon ground conductivity- also linked to water and minerals."

    That I'm aware of. I stay away from the "all eight feet at an angle" type installation.
    Mike N3PM
  6. KF5LJW

    KF5LJW Ham Member QRZ Page

    Mike FWIW the 8-foot minimum rod length does not have anything to do with Frost Lines. Perhaps you have confused that with NEC 250.53 (F) Ground Ring 30-inch minimum depth to get below frost line. NEC 250.53 (A)(1) makes it clear why rods must be a minimum of 8-feet length, reaching below permanent soil moisture level. Angles are only allowed if bedrock becomes an issue.

    NEC 250.51(A)(1)
    Below Permanent Moisture Level.

    If practicable, rod, pipe, and plate electrodes
    shall be embedded below permanent moisture level.
    Rod, pipe, and plate electrodes shall be free from
    nonconductive coatings such as paint or enamel.

    Here are a couple of discussions on a professional electrical forum I moderate. Both discussions have QRZ members from here, you will recognize and know them instantly. The moderators, all sit on, or have been in the NEC code making panels.

    Topic 1
    Topic 2
    W1PEP likes this.
  7. WT4W

    WT4W Ham Member QRZ Page

    You're misdirecting your anger. The problem isn't that things are becoming more efficient, it's that cheap junk is allowed to be sold without proper testing.
    AB6RF and N0TZU like this.

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