Contributor: Ralph, VE3BBM, via Jacques d'Avignon, VE3VIA
Noise Source: Light dimmer
Where Found: 152 kHz USB, but covers the LW and MW bands

Click this link to listen:  www.arrl.org/files/file/RFI Sounds/lightdimmer.mp3 

 

Learn More

Contributor: Ken, VE3HLS
Noise Source: My landlord's Sony TV set.
Where Found: 153 kHz USB, and several locations across the LW band.
Notes: Everyone knows TV sets make noise. But this was wasn't even on when the recording was made! I unplugged the set, then plugged it back in after a few seconds and the noise went away. However, it returned after the TV was turned on and then back off again.

Click this link to listen:  www.arrl.org/files/file/RFI Sounds/sony-tv.mp3

Contributor: Ralph, VE3BBM, via Jacques d'Avignon, VE3VIA
Noise Source: His neighbour's exercise treadmill!
Where Found:
Notes: It must have taken some interesting detective work to figure this one out! Nice work! (I think he had a narrow IF filter in at the time of the recording)

Click this link to listen:  www.arrl.org/files/file/RFI Sounds/treadmill.mp3

Contributor: Jacques, VE3VIA
Noise Source: Power Line Controls (PLC)
Where Found: Longwave band, various locations depending on the system in use.
Notes: PLCs are used for industrial control, and in commercial applications for applications like control of HVAC systems. They're finding increased use in homes and apartment buildings and condos as well. The X-10 control system is a basic PLC system that has been around for many years. PLCs use existing powerlines to send control signals, sort of a precursor to Broadband Over Powerline (BPL) that threatens reception on the HF bands.

Click this link to listen:  www.arrl.org/files/file/RFI Sounds/plc-4.mp3

Contributor: N4EKV
Noise Source: A Sharper Image Ionic Breeze Quadra (electrostatic?) air cleaner
Where Found: Unknown
Notes: N4EKV reports the noise from the unit is so strong that it can be received more than 100 ft away from the house! Beware, if you hear this noise your neighbour may have one!

Click this link to listen:  www.arrl.org/files/file/RFI Sounds/n4ekv-ionic-breeze.mp3

Added August 26, 2004
Contributor: Alessandro, IT9HYR
Noise Source: Now Identified!
Where Found: Throught the 20 metre band.
Notes: Noise comes mainly from one direction (north) and lasts only 2 or 3 hours, then stops. No powerlines to the north, only a condominium and some cellphone towers. Note from the waveform that this is 50 Hz noise, i.e., 5 repeats of the noise in the 1/10 second window, not 60 Hz as used in North America. --- Ken, VE3HLS

Note: Alessandro reported recently that he has identified the noise!

Dear Ken,

I find the noise source! It is a television set about 50 mt from my antenna in the north direction in the last floor of a condominium near my house. It is a Shaub Lorenz 20" stereo TV set made in Turkey. I belive that was a power supply mistake, but probably the noise came from the tube screen. At moment I cannot eliminate the noise, probably I will change (my charge) the TV with a new one HI HI.

Alex IT9YHR

The image to the right was recorded on 20-meter AM.

Click this link to listen:  www.arrl.org/files/file/RFI Sounds/it9hyr-am-14mhz.mp3

 

 

 

 

 

The image to the right was recorded on 20-meter SSB.

Click this link to listen:  www.arrl.org/files/file/RFI Sounds/it9hyr-ssb-14mhz.mp3

 

Added August 26, 2004
Contributor:

Web, KR4WM

Noise Source:

General Instruments DSR-920 4DTV (satellite) receiver

Where Found:

6 metre band.

Notes:

Web says "This one was particularly annoying to me. It was worst on 50.125.189, close enough to interfere with the 6M SSB calling frequency! I could hear it in my mobile nearly a mile away, and on my FT-847 in my shack, it was a perpetual bother! One day, on a fluke, I was working on my home TVRO (satellite) dish, and unplugged my General Instruments DSR-920 4DTV receiver, and had my FT-847 monitoring 6M, and noticed the noise went away when I unplugged the DSR-920! A few times of plugging it back in and unplugging it confirmed my problem -WAS- the 4DTV unit! So now I live with it, knowing that I am my own source of interference! At least the signal strength is S-0..."

Your website also helped me locate another source of interference, my two Ionic Breeze units! THANKS! -Web

Click this link to listen:  www.arrl.org/files/file/RFI Sounds/6m-4dtv.mp3

Added August 26, 2004
Contributor:

Bill, K2WH

Noise Source:

No-name brand electric blanket

Where Found:

Recorded on the 17 metre band, but found elsewhere.

Notes:

Bill says "The noise is from a no-name electric blanket that was emitting this signal.  I live on a lake and I was receiving it about S7 on peaks.  I located the source on the other side of the lake ~ 400 feet in a neighbors house.  While not terrible interference, I was curious to find the cause and silence it.  The recording was made on 17 meters with an 80 meter dipole and tuner.  The interference extended up to 6 meters but curiously not below 20 meters and with a squelched mobile receiver at 30mhz, would break the squelch just driving by.

Anyway, there is no manufacturers name on the blanket or control.  But it was made in China and distributed by Bed, Bath and Beyond.  The unit was only plugged in and not being used. The small remote (heating control) was sitting on the bed stand, was triangular in shape and had a round knob on it with large numbers 1-10.

Thanks and great site...K2WH

P.S. Dom if you read this, I found the source of the signal as described above.

Thanks Bill. Compare this with the recordings of electric blanket noise from the ARRL Lab below! ...Ken

Click this link to listen:  www.arrl.org/files/file/RFI Sounds/k2wh-pulse.mp3

Added January 24, 2005
Contributor: Mike, K7ING
Noise Source: Fox Repel-tron electronic insect repeller
Where Found: 1 to 15 MHz
Notes: "I have found the source of the RF noise. It's from a contraption called a FOX Repel-tron, see web site: http://www.americanpesttechnologies.com/

My neighbor a few doors north of me had one installed in his garage in an attempt to control bugs in his house. It's been installed for 6 months, just as long as I have been hearing the RFI. The RFI was strongest on my truck's AM radio (1600 KHz) right in front of his house, but I could still hear it 0.5 miles away.

I caught my neighbor outside while he was taking down his Christmas lights. He was nice enough to let me wander around his house with a portable radio, within 5 minutes we located the source. Flip the off-switch and poof, RFI is gone! He agreed to leave it off until he can contact the maker to fix it or remove it. He agreed to call me before he turns it back on (what a nice neighbor!!). He also admitted that it did nothing to control his bug population problem, saw no measurable change in 6 months. The product sounds like a perpetual motion machine to me, but I know nothing about bugs. All I know is that it was extremely aggravating to try to listen to any radio within the frequency range of 1-15 MHz, my house is about at least 500 feet from his.

You should put my post on your RFI web page. I could still hear the RFI about 0.5 miles away - makes me wonder if the contraption is actually RF-type accepted or not. The Repel-tron made 1-15 MHz useless and very frustrating to use, and wiped out my daughter's AM radio too. She likes to listen to a station at 1580 KHz - Repel-Tron successfully took it out.

I'd like to make sure some other ham or AM radio-phile that lives by one of these things can at least recognize the sounds from the MP3 recordings. It makes me angry that such an RF noise generator can actually be sold!!"

Click this link to listen:  www.arrl.org/files/file/RFI Sounds/k7ing-3545khz.mp3

Added January 24, 2005
Contributor: Eric Behr
Noise Source: Charger for Sony Digital 8 Video Camera
Where Found: 160m Band
Notes: "This one had everyone stumped for a while. Narrow signal, about 1.5 kHz, audible only on sideband around 1845 and a few other close-by frequencies. It turned out to be a Sony charger for a Digital 8 video camera. The frequency on which the signals were heard seemed to drift very slowly up as the battery was charging. MP3 file attached. Thanks for the useful collection!"

Click this link to listen:  www.arrl.org/files/file/RFI Sounds/eric-charger.mp3

Added February 13, 2005
Contributor:

Bryan, W1BRI

Noise Source:

Charger for Motorola cordless phone

Where Found:

140 to 170 MHz

Notes:

"I found your RF noise web site and figure it's best to send you what I sent to the FCC and ARRL on this Motorola cordless phone battery charger that was causing interference on one of our MMRA repeaters here in New England. Since writing up the article we found another house in the repeater neighborhood that had 4 chargers, we swapped them all out with fixed ones.

I have one of the bad ones on my bench and see that the center frequency depends on the voltage and current present at the charging terminals. As the battery charges the center frequency moves across the VHF high band. The rapid sweeping is from the AC ripple from the wall transformer when loaded due to battery charging. The modulation frequency is 60Hz.

The battery charger is the cause of interference in the high VHF radio spectrum, 140 to 170MHz, and is caused only when the cordless telephone handset is placed in the charging cradle. The interference appears as a rapid swept frequency, six megahertz in width, anywhere within the VHF high band spectrum. The battery charger is the cause of several sources of interference on two meter amateur radio repeaters.

The interference is best described as a buzzing sound with an approximate one second duty cycle. The interference has been heard in several locations, two of which are the source of the interference heard on the repeater input located 2500 feet from the source at an RF level of -80dBm. Directly in front of residence that contains one of these chargers the RF level measured -40dBm. "

Click this link to listen:  www.arrl.org/files/file/RFI Sounds/w1bri-charger.mp3

>> NEW - April 24, 2005 <<
Contributor:

Kevin, N6RCE

Noise Source:

Switching Power Supply

Where Found:

1 to 14 MHz

Notes:

"Here is a recording of a yet unidentified source of QRN. It's clearly a switching power supply. It put out a carrier every 200kHz, pretty accurately. It's about 8KHz wide. I've heard it from 1Mhz all the way up thru the 20M band, every 200kHz.

Every other harmonic is stronger, as expected.

The MP3 file was recorded with an ICOM R-20 in AM mode, with the filter width set to 15KHz. In this case, the frequency was 3200 kHz. The antenna was a simple shielded, tuned 80M loop made out of RG-58 coax."

Click this link to listen:  www.arrl.org/files/file/RFI Sounds/n6rce-sps-carrier.mp3

Added January 25, 2005
Contributor:

Kelly, N6KJ

Noise Source: Battery Charger
Where Found:

40m to 6m, loudest on 40 and 20.

Notes:

"I have a sound file that I recorded off the air last weekend. I heard the noise at my home 24/7 for several days (maybe longer), but it has now disappeared.

The noise I heard lasts for about 1 second and repeats every 24 seconds. I now suspect that it may be a wall-wort or battery charger since my next door neighbor is a building contractor and he has been building a new garage for months now. I DFed the noise and it points in the direction of his garage (or houses on the other side of course)so that may be a clue.

I heard it 24/7 on every band from 40M through 6M. I didn't check anything higher than 6M and my QRN level on 80M was too high to hear it. I heard it loudest on 40M and 20M."

(This is a long file, about 51 seconds. I left it this way because I thought the long gaps between occurrances of the noise might be a clue....Ken, VE3HLS)

Click this link to listen:  www.arrl.org/files/file/RFI Sounds/n6kj-rfi.mp3

Notes: One half of the electric blanket is turned ON and the other half is OFF, but plugged in. Recorded in USB and AM modes. The waveform of the AM recording is shown.

Click this link to listen:  www.arrl.org/files/file/RFI Sounds/w1rfi-1on-1off-am.mp3

Click this link to listen:  www.arrl.org/files/file/RFI Sounds/w1rfi-1on-1off-usb.mp3

 

 

 

Notes: One half of the electric blanket is turned OFF and the other half is OFF and unplugged. Recorded in USB and AM modes. The waveform of the AM recording is shown.

Click this link to listen:  www.arrl.org/files/file/RFI Sounds/w1rfi-1off-am.mp3

Click this link to listen:  www.arrl.org/files/file/RFI Sounds/w1rfi-1off-usb.mp3

Notes: One half of the electric blanket is turned ON and the other half is OFF and unplugged. Recorded in USB and AM modes. The waveform of the AM recording is shown.

Click this link to listen:  www.arrl.org/files/file/RFI Sounds/w1rfi-1on-am.mp3 

Click this link to listen:  www.arrl.org/files/file/RFI Sounds/w1rfi-1on-usb.mp3

Notes: Both halves of the electric blanket are turned OFF and are plugged in. Recorded in USB and AM modes. The waveform of the AM recording is shown. Note that this waveform is 2.5 seconds in length, where are others are 0.1 seconds long. This is to better show the train of pulses emitted by the blanket. It would not show up on a 0.1 second view.

Click this link to listen:  www.arrl.org/files/file/RFI Sounds/w1rfi-2off-am2.mp3

Click this link to listen:  www.arrl.org/files/file/RFI Sounds/w1rfi-2off-usb2-mod.mp3

Notes: Both halves of the electric blanket are turned On and plugged in. Recorded in USB and AM modes. The waveform of the AM recording is shown.

Click this link to listen:  www.arrl.org/files/file/RFI Sounds/w1rfi-2on-am.mp3

Click this link to listen:  www.arrl.org/files/file/RFI Sounds/w1rfi-2on-usb1.mp3