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Author Topic: RFI- Anyone recognize this?  (Read 20300 times)
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Carl WA1KPD
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« on: October 20, 2011, 10:57:56 AM »

I have recently had an awful load of RFI show up at the shack. I can hear it from the BC band all the way to 10 meters. It peaks at about 2.087 MCS where it is 20 over. On 20 meters it sounds more like a white noise but is S-6

It is 24/7 and stays the same in signal strength. It sounds like power line noise but I did not think I would see the various peaks. I have been able to shut off all power in the house (except shack) so far with no impact.

Before I start signal hunting and possibly talking with neighbors, does anyone recognize this pattern?
Thanks,
Carl
WA1KPD


* RFI.jpg (171.02 KB, 958x643 - viewed 457 times.)
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Carl

"Okay, gang are you ready to play radio? Are you ready to shuffle off the mortal coil of mediocrity? I am if you are." Shepherd
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« Reply #1 on: October 20, 2011, 11:21:45 AM »

I had a problem like that once and turned out to be the neighbor across the street. 1 phase connection at the peak of the house was loose. Power Co fixed it when they went 1/2 dark.
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W1AEX
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« Reply #2 on: October 20, 2011, 12:23:10 PM »

Is that 120 KHz spacing between each pair of pulses? Any chance you could post a short MP3 audio file of what it sounds like Carl?
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W2ZE
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« Reply #3 on: October 20, 2011, 12:34:08 PM »

I had a problem with my QS1R when I first fired it up that was similar. It turned out to be the PC suck-ply was bad. I replaced with an EMI suck-ply and the problem went away. I would try that first before pestering your neighbors  Wink.

Mike
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WD8KDG
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« Reply #4 on: October 20, 2011, 02:49:44 PM »

Gotta new one in the hood here in Springtucky, Orygun. Sounds like two or more BC stations are being mixed/detected by something. 40 dog biscuits @ 3.870 MHz on the R-390/A. About 2 dozen or more harmonic in the ham bands up to 10 meters.

Wonder if the new HD stuff is causing RFI?

Craig,
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Ham radio is now like the surprise in a box of "Cracker-Jacks". There is a new source of RFI every day.
WA1GFZ
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« Reply #5 on: October 20, 2011, 03:12:31 PM »

Mike,
You have a QSR1, Good Man
The exciter should be cool.
I run a modified MRI amp on my HPSDR set up.
Pair of MRF150s in the final. I modified an erbteck board that cost me $69 for a 3 stage amp P-P FETs. works 160 through 6.  PM me if you decide to go that way and I can provide the mods. CTR Surplus sells the MRI amps.
W1VD and I have modified these boards. Very nice stuff.
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KM1H
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« Reply #6 on: October 20, 2011, 03:38:55 PM »

Streetlight? It doesnt have to be on. A neighbors light also a suspect.

Carl
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Carl WA1KPD
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« Reply #7 on: October 20, 2011, 04:22:34 PM »

Thanks guys for the help.

Here it is. It is recorded on one of the peaks, but it sounds no different no matter where you are.

No street lights within a good 1/2 mile and all power in the area is underground. I have always had some sort of nose that seems to carry in on the underground feed for the poweline, but never this bad.

I am wondering if it was something that changed during the hurricane- we were out of power for a week. But since I have not been in the shack much I really cannot say when it got this bad.

* Record0_20111020_200947.wav (1481.7 KB - downloaded 263 times.)
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Carl

"Okay, gang are you ready to play radio? Are you ready to shuffle off the mortal coil of mediocrity? I am if you are." Shepherd
W2ZE
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« Reply #8 on: October 20, 2011, 05:08:51 PM »

Quote
You have a QSR1, Good Man

Yes, I am dabbling in SDR now. Phil's support is top notch, and its a great product.
I can't wait for the exciter and the front end filter board. Surplus ripoff of Neb. also has 200 watt amps with a heat sink and basic control circuitry, but I will be interested in what you have.

Comparing the qs1r to an r390a is night and day. The r390 sounds good untill battle mode, the qs1r far surpasses in featrures and options once in battle mode. I won't go back to any othe rx.

Mike
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flintstone mop
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« Reply #9 on: October 20, 2011, 05:27:43 PM »

That sounds like TV video. Horizontal pulse.
Any surveillance systems nearby? We tracked down a real strange problem from a TV antenna amplifier power supply emitting something similar to this noise.
You might try to find the strongest receive frequency with the SDR and get a portable receiver and start driving around, watching or listening for an increase in signal strength.

A router or rooter ( home computer )network could cause this problem near 20M also
Fred
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Fred KC4MOP
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« Reply #10 on: October 20, 2011, 05:52:01 PM »

Doesn't sound like power line noise,  more like something running, could be almost anything.  Check your QTH by using a portable receiver outside and then shut off everything including all your electronics in the shack.  This is what you should start with.

Fred
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« Reply #11 on: October 20, 2011, 06:39:20 PM »

For what it's worth that is 60 cps pulse noise. I took your wav file and cut it down to .1 seconds and it neatly shows 6 cycles of pulse noise. It sure is ratty sounding. Hope you can locate it quickly. I would not hesitate to call your local utility company for assistance if the source is not readily located with a portable receiver.


* .1 seconds.jpg (39.05 KB, 800x440 - viewed 369 times.)
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« Reply #12 on: October 20, 2011, 07:05:09 PM »

That sounds like TV video. ...

It kind of looks like it, too. Do you have a neighbor with a plasma TV? Some of them are prolific RFI generators.
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73 Mike 
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Jim, W5JO
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« Reply #13 on: October 20, 2011, 07:15:52 PM »

Cell phone charger?  Something like that?
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WD8KDG
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« Reply #14 on: October 20, 2011, 07:35:58 PM »

Just listened to the wav file, sounds like what my backyard neighbor has in their house. Gud luck!

Craig,
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W1RKW
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« Reply #15 on: October 20, 2011, 07:55:31 PM »

sounds similar to the noise I had here. determined it to be a neighbors plasma TV. 

Carl, can you pick it up on your vehicles AM radio when tuned to 1700?  Drive by your QTH with your radio tuned to the upper end of the AM dial. You may be able to localize it.  That's how figured out where my noise was coming from.
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Bob
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His fear was when I turned it on for the first time life on earth would come to a stand still.
Steve - K4HX
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« Reply #16 on: October 20, 2011, 08:10:52 PM »

Lots of harmonics. The 60 Hz reps drop out at the higher freqs leaving just 120 Hz bands. It's doesn't sound like some of the switching supplies I've heard.



For what it's worth that is 60 cps pulse noise. I took your wav file and cut it down to .1 seconds and it neatly shows 6 cycles of pulse noise. It sure is ratty sounding. Hope you can locate it quickly. I would not hesitate to call your local utility company for assistance if the source is not readily located with a portable receiver.


* spectrogram.gif (286.14 KB, 1591x841 - viewed 389 times.)
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K5UJ
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« Reply #17 on: October 21, 2011, 05:48:35 AM »

If it is a plasma tv you are probably going to have difficulty.  I understand with them it is the screen itself that does the radiating.  Try telling someone he can't use his $2000 tv anymore.  you are going to have to come up with an antenna or rx network that nulls the source.  OTOH I think you said it is there all the time.  If true, that rules out a tv set unless the viewers are so brain fried they have the set on night and day all the time  Roll Eyes  I wonder if it is something like that AT&T Uverse.
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Jeff W9GY
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« Reply #18 on: October 21, 2011, 07:00:50 AM »

With plasma TVs, the noise changes as the scenes change.  My nieghbor had a cordless drill charger that made constant noise like this...
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Jeff  W9GY Calumet, Michigan
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« Reply #19 on: October 21, 2011, 08:27:59 AM »

CTR Surplus has a web site and sells on epay. I've bought a bunch of stuff from them. John usually has some MRI boards kicking around. You do need to mount the board on a bigger heat sink so it takes some work. The board is a foot square but I cut off all the control stuff and build a little bias module.
I have all the mods and pictures if you want to go that way I can send them to you. I need to put a 16 dB pad on the output of my 1/2 watt exciter to get the right drive. I also have schematics. I also have a pair of 1200 watt modules I hope to build into a linear someday.
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KW4DE
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« Reply #20 on: October 21, 2011, 09:30:58 AM »

I had similiar noise a few weeks ago and it was an old color TV that my daughter had hooked up radiating broadband garbage via the coaxial hookup.  One heterodyne was 1.882 with blips and burps high and low throughout the bands. Made good target practice.
Darrell KF4DX
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KA7IUS
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« Reply #21 on: October 21, 2011, 09:55:21 AM »


Hello All!

     Sounds to me like one of the neighbors is growing pot to me.

    Tnx,
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KD6VXI
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« Reply #22 on: October 21, 2011, 10:48:26 AM »

Having attempted to practice Ham Radio in Santa Cruz Mountains, I have firsthand knowledge of dealing with the growers and their ballasts.

That's NOT a ballast noise.  The digital ballast noise will go almost to 6 meters....  I detected it into the mid 40 mhz range.
 
Was interesting when I'd knock on the door.  "Hi, your digital light ballasts for your marijuana grow are causing me problems with my licensed transmissions".......

One showed me their prescription.  The others just shut the doors.

You can get radiation from the different kinds of bulbs they use if they aren't screwed in all the way, too...  But, I've not heard anything like the noise your .wav is when dealing with the growers.

TV maybe?  Bad utility connection somewhere?  Time to get the AM radio out.

--Shane
KD6VXI
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W8IXY
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« Reply #23 on: October 21, 2011, 12:33:14 PM »

See if anyone installed an automotive battery charger nearby.  Last winter I turned the receiver on one day and >60 over 9 noise/buzz.  I couldn't hear anything but noise up through 6 meters.  Got out the portable and found the noise next door, about 30' from my antennas.  He'd bought a cheapie battery charger for his boat battery.  He apologized for causing the noise.  I offered to buy him a better one, but he said he would put it on a timer, and run it after 2AM.  He did and no more problem.  But to date, that's the worst noise generator to affect me so far.   Runner ups were a floodlight with a built in photocell, and a touch lamp.   Good luck.

73
Ted  W8IXY

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WD8KDG
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« Reply #24 on: October 21, 2011, 12:48:00 PM »

The only real CURE is for every ham operator to start filing complaints with the FCC every time & every day there is RFI heard on the station's receivers.

Craig,
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Ham radio is now like the surprise in a box of "Cracker-Jacks". There is a new source of RFI every day.
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