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Author Topic: Appears to be switching p/s RFI on 40 meters  (Read 15668 times)
W2MV
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Posts: 244




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« on: October 08, 2016, 04:24:18 PM »

Started some time within the past two weeks. Can only hear it on 40 meters, buzzy signal clusters spaced about 65 KHz apart. I'm having a problem homing in in the location of the source. I have an RF-PRO1B loop on the roof, rotated it, but could not find a null. I walked around within a couple of blocks with a portable SW receiver and an Alex loop antenna. When I walk past my house in front of it, the signal seems to be strongest a bit north of the house, but it's hard to get a bearing (null.) When I walked around the block in the back of the house (another house there too) , the signal was strongest in the vicinity of maybe 50-100 feet north of being "abeam" of my house. However, when trying to get a null, the loop null (signal source) seemed to be coming from utility wires running  from one side of the street to the other. I could not seem to home in on a source coming from a structure such as a house.

Perhaps having an attenuator in the antenna feedline might help, to adjust the RFI level to just above the background noise level.

Any suggestions would be appreciated.

Thanks
Alan, W2MV
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N3QE
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Posts: 5598




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« Reply #1 on: October 09, 2016, 05:05:06 AM »

Chances are if you walk ALONG the power lines you will hear the a null in noise every half wavelength - every 20 Meters or feet. The power lines can conduct this kind of noise along very great distances.
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NK7Z
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« Reply #2 on: October 09, 2016, 06:20:20 AM »

Move up in frequency, if you can still hear it, try a DF session that way.  Otherwise, see:
http://nk7z.net/category/info/rfi-mitigation/
for more information...
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Thanks,
Dave
Amateur Radio: RFI help, Reviews, Setup information, and more...
https://www.nk7z.net
K5LXP
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« Reply #3 on: October 09, 2016, 07:51:50 AM »


Did you try turning off the mains to your own house?  You may be certain it's not coming from there but there's only one way to know for sure.  Takes all of 10 seconds.

Mark K5LXP
Albuquerque, NM
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W2MV
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Posts: 244




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« Reply #4 on: October 10, 2016, 10:55:01 AM »

Thanks to all for their advice...the 40M RFI disappeared as quickly as it appeared Smiley
If it DOES come back, I'll be better equipped to locate it.

The way things have gone over the past few years, chances are something else will rear its ugly head on one of the bands within the next few months.

Yes, I did kill the main breaker to my own house as a first step, but no difference.

Alan, W2MV
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KB1NCP
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Posts: 0




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« Reply #5 on: October 18, 2016, 11:47:16 PM »

I am getting exactly the same thing at my station. Actually all summer I was getting it on 75 meters strongest on 3.809 plus or minus. I always had a lesser noise on 40 meters but the same 60-65 khz apart. Like a harmonic from the noise on 75 meters. Notice no noise on the A.M. broadcast band. On Oct 15 or 16 the 75 meter noise went away, and the strong noise on 75 was on 40 meters. I have also for a long time getting a digital type sound like oscillating on 14.178.00. At this time 2 A.M. Oct 19 no noise on 40  but a jamming type machine gun sound on 3.860.00 not the usual swooshing up and down sound that plagued me all summer. Seems there is some shift in frequency based on either temperature and or daylight.  I understand HARP has been or recently been activated again? Aside from this does anyone know of a forum specifically for Hams posting interference signals. That would help hams quickly determine if a noise is in home/local or being propagated over a large erea. Does anyone else want to see the ARRL and the FCC start to enforce Part 15, and stop the corporations from letting the shitty consumer products infiltrate the air waves. Who owns the Air waves ? Who owns the Seas ?  I'll drop it, Hams need to unite because with all of the cheap electronics, Telecom industry, Alarms, Solar panels Cheap junk let alone the short cuts Installers make trouble big on the Horizon. Bandwidth for dollars spectrum to the highest bidder. What say you.

Bill kb1ncp
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KH6AQ
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« Reply #6 on: October 19, 2016, 06:51:39 AM »

If the noise source is a switching power supply it will drift up and down the band. If it's a monitor it will be rock steady.
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VK3TEX
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Posts: 74




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« Reply #7 on: October 30, 2016, 02:09:06 PM »

I have the same noise coming from a few houses up from mine. Its faulty or non existant filtering in this neighbors TV. It started happening a couple of months ago. I proved to this neighbor by getting her to switch this TV off momentarily while I was outside the house with an SW receiver tuned to the noise. She refused to agknowledge her TV was producing the noise and refused my offer to add external filtering. Totally uncooperative.
I feel your pain.... my noise is 24/7 as her TV is switched on all the time at the wall switch. Uses her remote to switch TV on and off.
She is what you Americans call a " stupid redneck". Here in Australia we call them " stupid Ferrals".
I have to put up with the noise either til she moves, (hopefully soon!) or the TV dies or the house burns down.....
I hope your neighbors are nicer to deal with as I have had the luck to strike the worst neighbor in out street.
And correct, this noise also drifts up and down the band periodically....

Les, VK3TEX.
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KC2QYM
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Posts: 958




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« Reply #8 on: November 08, 2016, 12:24:03 PM »

Unending cascades of RF noise are destroying the pleasure of ham radio in and around major cities and suburban areas.  the sources are unending due to cheap power supplies, dirty HD monitors and entertainment systems, lighting systems, etc.  The FCC doesn't care and can't be bothered trying to enforce RF abatement procedures after the fact.  By the time complaints from hams come in, millions of the devices are already in use and countless more on store shelves, mail order warehouses, and in the supply route from China.  Yeah, go try and stop it...
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W2MV
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Posts: 244




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« Reply #9 on: November 15, 2016, 04:46:27 PM »

It's back...started several days ago on 40 M. Did a bit of DFing and found (sort of) a null on my RF-PRO1B loop. Will be snooping around the area some more. I really don't want to knock on someone's door if the RFI is not from that location, so I have to be sure.

Buzzing signals with clusters spaced every 55 KHz or so.
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NK7Z
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« Reply #10 on: November 15, 2016, 05:26:06 PM »

Unending cascades of RF noise are destroying the pleasure of ham radio in and around major cities and suburban areas.  the sources are unending due to cheap power supplies, dirty HD monitors and entertainment systems, lighting systems, etc.  The FCC doesn't care and can't be bothered trying to enforce RF abatement procedures after the fact.  By the time complaints from hams come in, millions of the devices are already in use and countless more on store shelves, mail order warehouses, and in the supply route from China.  Yeah, go try and stop it...
I must disagree, the FCC does care!  I have shut down several RFI generators, and the FCC has sent letters as a result of proper reporting being given the FCC.  So yes, the FCC, and the ARRL do care, and yes they both want to stop the RFI... 
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Thanks,
Dave
Amateur Radio: RFI help, Reviews, Setup information, and more...
https://www.nk7z.net
NK7Z
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« Reply #11 on: November 15, 2016, 05:32:19 PM »


Buzzing signals with clusters spaced every 55 KHz or so.

Take a look at http://nk7z.net/sdr-rfi-survey-p1/

and you will see a method of collecting a massive amount of data, and displaying it in a way that is clear and easy to understand.  It helps to understand your RFI source.
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Thanks,
Dave
Amateur Radio: RFI help, Reviews, Setup information, and more...
https://www.nk7z.net
KB7WOX
Member

Posts: 56




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« Reply #12 on: November 21, 2016, 06:37:07 AM »

Unending cascades of RF noise are destroying the pleasure of ham radio in and around major cities and suburban areas.  the sources are unending due to cheap power supplies, dirty HD monitors and entertainment systems, lighting systems, etc.  The FCC doesn't care and can't be bothered trying to enforce RF abatement procedures after the fact.  By the time complaints from hams come in, millions of the devices are already in use and countless more on store shelves, mail order warehouses, and in the supply route from China.  Yeah, go try and stop it...
I must disagree, the FCC does care!  I have shut down several RFI generators, and the FCC has sent letters as a result of proper reporting being given the FCC.  So yes, the FCC, and the ARRL do care, and yes they both want to stop the RFI...  

The FCC doesn't even care about band intrusion, just more wishful thinking
« Last Edit: November 21, 2016, 06:55:47 AM by KB7WOX » Logged
W2MV
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Posts: 244




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« Reply #13 on: November 21, 2016, 11:26:02 AM »

I installed HDSDR with my SDRPlay last night, and looked at some spectral views. The antenna was a 40M dipole, so the gain drops above and below the resonant point but I figured what the heck. Wow...there was a very vivid display of my switching p/s noise clusters, spaced apart at about every 55 KHz, from at least the 60M/5 MHz band (as low as I listened), up past the 40 M band. I will do some scheduled data collection, but I suspect the noise is on 24x7. Probably a wall wart or some similar device...cell charger, etc....
The noise IS being coupled to the power line. I shut off my main breaker (again) just to make sure, no change in the RFI, and it was even stronger when the portable RX was near the breaker panel.

So now it's matter of finding it, the hardest part. As I mentioned, I have a feeling of the general direction obtained from a null with my RF-PRO1B loop, but it could be wrong. I will just need to walk around the area again...a relatively congested suburban setting. If and when I am sure of the house it's emanating from, then the next fun step. "Hi...I'm your neighbor from a few blocks away..."

Happy Turkey Day!
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W2MV
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Posts: 244




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« Reply #14 on: December 05, 2016, 11:34:31 AM »

Good news and bad news. The good news (perhaps) is that the switching p/s RFI disappeared just before Thanksgiving (and the CQ WW CW contest)! Of course, it has done this before and has come back.

The bad news...a new intermittent (quickly on and off) buzzing, wideband noise across 40 M. I almost thought it was some kind of CW signal because the on and off buzzing (arcing?) has that type of pattern.  Maybe it's a neighbor's Xmas lights and will go away. I've not tried to track it down yet.

Purchased a National RF HFDF and hope it will help.
NK7Z's "Whack-a-mole" analogy is appropriate...a constant battle.


Cheers.
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