Can anyone identify this regularly repeating signal?

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  • Updated 3 years ago
This signal (see clip) repeats across 20M 24/7.  It comes in through the antenna, regardless of which antenna I am using.  It disappears when the antenna is disconnected.  Can anyone identify it as perhaps TV Cable or DSL or Power Line?
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K0UNX

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Posted 3 years ago

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Burt Fisher

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Computer power supply as it is with me.
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George Molnar, KF2T, Elmer

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I've seen that from a router, also.
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Walt - KZ1F

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What's interesting is I see essentially the same thing on 160 and 80 but mine are every KHz. Jim's is widely space. I was also meaning to ask Jim if his spikes were fixed or vary. I also put two dbl looped ferrited on my power line, to no avail. Two may be way too few, if I recall a pic Al shared some time ago.

@Al, would you repost that pic if it is handy?
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K0UNX

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Those spikes are fixed in both frequency and amplitude, 24/7.  They are very much LOCAL in nature.  I haven't yet eliminated a computer power supply as the source, but have eliminated the radio's power supply, turning it off and running on battery power.

On 80, I have signals starting at 3.8 and running to 5.1 mHz, and HAVE identified them as the phone company's VDSL service.  Many local hams are working with the FCC and the phone co. to try to resolve the interference.  It is very broadband, and I measure it at about 16 dB.  Here is a picture:
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KD4HSO

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It's probably a switching supply running at ~60 kHz. Really bothersome for me too. See my video and post here:

https://www.youtube.com/watch?v=E_r9c...

https://community.flexradio.com/flexr...
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Bob G W1GLV

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My new efficient air conditioner has a waveform similar to that. Goes away when the AC goes off.
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Walt - KZ1F

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It was 37 here this morning Bob. We've already transitioned from AC to nothing to heating season here in CT. Of course the W1 doesn't mean you are still in New England. We'd be gone if it weren't for the kids and grandkids.
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Bob G W1GLV

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Walt, I'm in Florida. Left MA 18 years ago, never looked back. 73
Walt, I'm from Southbridge, MA, I see you live in Dayville, CT.
(Edited)
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Walt - KZ1F

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We used to live in Grafton then Templeton. I started my CFI training out of Southbridge. My wife and I both grew up in RI and both our kids still live there. I never planned to retire this far north or in a place this expensive to live. Best laid plans...
(Edited)
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KD4HSO

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Put down a slice as a frequency marker and let it run for several minutes. Does the noise drift a few 100 Hz?
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Wim

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I have exact the same spurs like you show on 14.150 and 14.210 and 14.270  and some other bands indeed. If I switch to ANT2 (nothing connected) they disappear and if I stick
a small wire in ANT2 I can see them a little bit so the external antenna is picking them
up better, to me looks like it's not generated in the shack.

One good test is to run the Flex from a 12V battery and SmartSDR on a battery powered laptop 
and turn off all breakers for the house. That way you can see if it's generated by your house
equipment or the neighbors..     A test I'm going to run myself shortly.
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Walt - KZ1F

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That is my experience as well, the signals are picked up from the antenna. Please be sure to report your findings from the pure battery tests.
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Larry Benoit

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This may be caused by a router. You probably have the same RFI signature on other bands, particularly 10 meters.   To confirm, shut off the router, shut down your Flex transceiver, disconnect your computer from your network, connect the Flex directly to your computer and restart radio.  See if the RFI is gone.

73,

Larry KB1VFU





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Ken - NM9P, Elmer

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I have a mixture of noise like that. Some of it comes from my router. Another source is the Chargers for our cordless phone system. Then there is the variable speed blower on my HVAC system, my wife's laptop power supply, and one of our TV's. Most of these I would be blissfully unaware if it were not for the wide and pan scope on the 6500!
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Walt - KZ1F

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Ken? Taking each individually, have you been able to eliminate or mitigate their presence, if not audibly, visually????
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Ken - NM9P, Elmer

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I have removed a few of them. The rest will be a winter project, falling in line after several other endeavors! Now that I have gotten my remote working with the iPad again it will be much easier to unplug and watch the screen...
(Edited)
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David Warnberg

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Jim, does your neighbor or anyone close happen to have a DC motor running??  I have a DC pool pump, when it's on it looks just exactly like that and runs across just about all bands..
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K0UNX

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No, there aren't any water features in the neighborhood.  I disconnected the cable, and turned off my cable router, and there was no change.  I also looked at it with my MacBook Air, running on battery, with the desktop computer off, and no change.  I have to do these things in the morning before 20M opens up.

It is more of a curiosity than anything else.  I was mainly wondering if what I'm seeing is being seen elsewhere -and it is.  One fellow (WIM, in Santa Clara) even saw the same spikes at the same frequencies.
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George Molnar, KF2T, Elmer

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Noise mitigation is a tough business. Howard (KY6LA) put out a nice presentation some time ago you can search for here. My experiences are on my QRZ.com page and closely match Howard's. Still remember the Words of Wisdom from W4TME - the best thing about a Flex is the Panadapter, it's also the worst thing. Now you can see and obsess about noise you would have never known about before (story of my first year with a 6500!).

Similar noise on 10m in the attached picture. Sadly coming from outside my home.

Good luck...
(Edited)