Ceiling Fan RFI - on all HF bands

Discussion in 'General Technical Questions and Answers' started by K1HL, Aug 23, 2018.

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  1. K1HL

    K1HL Ham Member QRZ Page

    My neighbor has no less than eight Harbor Breeze (a Lowes proprietary brand) ceiling fans. They are each operated with a handheld remote control transmitter. I believe these fans to be of DC motor design. The RFI is similar to that which can be heard from an unfiltered switching power supply, only much worse. Birdies can be heard from the AM broadcast band through ten meters at levels as high as 20db above s9. My receiver is entirely unusable. Fortunately, the neighbor is friendly, so a reasonable solution would not be rejected. Any ideas? Thanks. Harry
     
  2. KC8VWM

    KC8VWM Ham Member QRZ Page

    I didn't see the part where you had taken measures to specifically identify the noise source.

    How did you come to the conclusion these ceiling fans are the problem?
     
  3. K1HL

    K1HL Ham Member QRZ Page

     
  4. K1HL

    K1HL Ham Member QRZ Page

    My neighbor is cooperative. Confirmation of source was easy as it can get... Brought portable SWL receiver, turned off the fans, and good bye noise...
     
  5. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I see they're all made in China and have optional LED light kits.

    Does your neighbor have the LED lights installed?
     
  6. KC8VWM

    KC8VWM Ham Member QRZ Page

    Are the ceiling fans connected to a variable dimmer switch mounted on the wall?
     
  7. K1HL

    K1HL Ham Member QRZ Page

    Yes, there is a globe containing lamps (presumably LED's) beneath the fan blade assembly. I didn't check to see if the lights are switched/dimmed separately from the fan motor. Will research that. Good idea. Will re-visit neighbor after they've had a few drinks and are OK with another visit.
     
  8. K1HL

    K1HL Ham Member QRZ Page

    Yes, the remote control has speed selector for the fan. I do not know if it has a dimmer for the attached light. I don't recall the light control details. Will return to neighbor for another look. Thanks for the help.
     
  9. KC8VWM

    KC8VWM Ham Member QRZ Page

    Besides looking for wall dimmer switches also inspect if the "light" in the ceiling fan is setup to operate at different brightness levels by flicking the wall switch on and off quickly a number of times.

    The way many newer ceiling fan with internal "dimmers" work is by altering the AC waveform. That is to say the waveform is no longer smooth causing "buzz" which is a significant source of RFI.

    Modern ceiling fans also have a power limiting circuit as a built in safety feature. If this circuit detects lighting installed that's higher than the rated bulb wattage being used, the circuit will reduce power supplied to the bulbs by rapidly switching them on and off faster than the human eye can see. In other words, generating yet another significant source of RFI.

    So basically, what you are looking for is any kind of built in light dimming capabilities and not necessarily the "ceiling fan" itself as the cause of your RFI problems.
     
    Last edited: Aug 24, 2018
  10. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    According to their on-line specs (I have no clue if those are accurate) the lamps in these units are always LEDs, not incandescent. That doesn't make them any less "noisy," though.

    Remember, these are very inexpensive ($39-$99 depending on size and features) 100% Chinese-made fans.

    I doubt they were ever even tested for radiated/conducted emissions. By anybody.

    You probably know another Chinese item that describes by its name a lot of consumer products coming from there.
    upload_2018-8-23_15-27-52.jpeg
     
    N0TZU likes this.

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