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Author Topic: this one turning in a real head scratcher severe RFI  (Read 1059 times)

W8OB

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this one turning in a real head scratcher severe RFI
« on: October 18, 2021, 08:01:14 AM »

I have been getting a real butt kicking from 20 db over s9 very broadband QRM from 30 khz right up to 390 mhz or so. I spent 4 hours this morning out searching for the problem, my local utility AMEREN has also spent quite a bit of time trying to locate the problem. I took three  direction readings which pin point the area, when I get in the area that I suspect the noise is coming from its almost impossible to get a null reading with a 3 el yagi and a 135mhz receiver its like I am surrounded with the noise. Ok so I tried a ultrasonic receiver on all power poles in the area and nix plenty of arcs from passing vehicles but no poles, I continued my trek down to an area that has underground power and still getting the noise, which I traced to a comcast CATV pole that was fed with aluminum hardline and had two service taps running to the served houses. I again drove away and took 3 readings and they all point to the pole. Do you suspose the RFI is riding piggyback on the comcast cable? The weird thing is this seems to be confined to a say 10 block square area and if you get to the edges of the area the yagi will null out the noise off the back of it. I also used a small spec analyzer and it shows the noise all across the spectrum.  I am attaching a picture of the band scope off of my ft-991 showing the noise. This noise will appear and stay up to several days and then disappear for several days. Any ideas?   Well guess for some reason I can't post pictures
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N2AYM

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Re: this one turning in a real head scratcher severe RFI
« Reply #1 on: October 18, 2021, 10:11:39 AM »

I think you should call back the person you last spoke to at your local AMEREN utility and tell this
person of your noise search results and let that person do his/her job in this noise search - they
should be much better equipped than you to handle this kind of thing.
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K6SDW

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Re: this one turning in a real head scratcher severe RFI
« Reply #2 on: October 18, 2021, 11:31:44 AM »

Sounds very familiar.....you're not suppose to do this, but I take out a 1-pound sledge hammer and wack each poles, usually the offending pole shows up in an AM receiver. The utility company will be "horrified" you wacked their poles.....

GL/73
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KC6RWI

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Re: this one turning in a real head scratcher severe RFI
« Reply #3 on: October 18, 2021, 06:34:18 PM »

I'm not a cable technician, but it seems to the cable signal is very strong, in fact I have picked up tv audio at 178 MHz and my best guess is that I was picking up some cable signals. If that signal was riding on the cable it probably is coming from many directions.
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W8OB

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Re: this one turning in a real head scratcher severe RFI
« Reply #4 on: October 22, 2021, 12:23:59 PM »

UPDATE:  I threw out the CATV idea and hit it one more time. I found the bulk of the noise is coming from  the smart meter transceiver located on the suspect pole. Ameren had already removed one that was not in use for noise. They contain a switching power supply that is apparently  back feeding noise into the line and of course the whole area is full of noise. Now all I got to do is hope the two crews will work together and fix the problem. To be continued
« Last Edit: October 22, 2021, 12:36:13 PM by W8OB »
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W8OB

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Re: this one turning in a real head scratcher severe RFI
« Reply #5 on: November 20, 2021, 06:48:49 AM »

Final update: about 3 weeks ago I received a recorder call from the utility company saying that a problem was detected and was scheduled to be repaired very soon. I followed up and it was indeed the smart meter concentrator unit. Since then I have not had any problems other than
 very slow lived line arcing during windy conditions from another source. Doing a analyzer sweep I still detect some very low level noise signatures from other locations but these are running like s1 to s2 in level under the normal band noise. I think it won't be new technology that ruins radio reception but the cheap switching power supplies these things contain.
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WB4SPT

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Re: this one turning in a real head scratcher severe RFI
« Reply #6 on: April 29, 2022, 06:24:52 AM »

Utilities get a pass on Part 15 unintentional radiation, but reading the text, one is to believe that exemption only applies to equipment in their actual possession, and not to subscriber or "fielded" equipment in the public domain.  In any case, makes you wonder what, if any, rad or cond. testing was done on this mesh meter read equipment.
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