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RFI -- The search continues

Discussion in 'General Ham Radio Discussion' started by archjeb, Sep 29, 2018.

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  1. archjeb

    archjeb Member

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    So, I know I've got other threads somewhat related to RFI - or at least antenna issues and trying to deal with related RFI issues.



    But, I took some time this afternoon to shut down the breakers and run the radio on battery power to see what I have for on-premise noise and what is off-premise noise.

    First off, there is indeed power company noise. Here is the clip (attached) of what I'm hearing while running on battery power and the main's shut off.

    As a side note, my service entrance is almost 300' from the power pole/transformer and underground from the pole to the house. The Electric companies transformer is up the pole. So the 300' doesn't include the climb through the conduit along the side of the pole. Let me know your thought's on the attached mp3.

    Now for inside the house. oh my, I can't believe how much hash and noise I'm getting. A Raspberry PI wall wort is creating the most noise and is radiating all the way outside the house! Not sure what is wrong with it...but I'll have to look at replacing.
    Do the Ferrite Chokes (mix 31) help with this on the DC power side of the wall worts? Or is it really a rip and replace kind of solution?

    The reason I ask, some of the wall worts are harder to replace for some more proprietary connectors on other equipment. Although they're not as bad as this particular switching power supply, they are making noise too.

    At any rate, I can see that this is going to be a long,long journey to remove all the noise makers. I can't believe how much noise is created by all these electronics in the house. I'm already pulling my hair out trying to track all this stuff down.

    Now I understand way some Hams like to take to low power (QRP) camping in the woods so they are well away from all this noise...

    -J
     

    Attached Files:

    Shadetree Mechanic likes this.

  2. Mudfoot

    Mudfoot Sr. Member

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    Try to replace switching wall warts with linear ones. That will be a YUGE help. Call electric company to come out and sniff the area. If that's all the power line noise you have, should be a quick find, unless you have multiple intermittent sources that wasn't present at time of recording.
     
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  3. archjeb

    archjeb Member

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    I'll work on doing that, i.e. replacing with linear power supplies.

    After additional testing, I found that the Raspberry PI noise was really coming from the USB to serial adapter which I have that goes to my alarm panel (alarm panel is RS232). I don't know why, but the twisted pair cable from the USB to Serial adapter that goes to my alarm panel is generating the horrific noise. I tried a snap on choke and that didn't make a difference. Note sure what else to try, but maybe shielded Cat5e for that short link?

    I'm starting to pull my hair out on all this noise :unsure:
    -J
     
  4. Tallman

    Tallman W9WDX Amateur Radio Member, KW4YJ EXTRA class

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    Mudfoot is right it is all power line noise. Ferrite beads on the DC power out will do you no good at all since it is being radiated from the wall wart.

    Home security systems are noisier than all get out.
     
  5. Mudfoot

    Mudfoot Sr. Member

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    The recording he posted, sounds like line noise coming from a nearby pole.
     
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  6. Tallman

    Tallman W9WDX Amateur Radio Member, KW4YJ EXTRA class

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    Your right. The sound will also vary with humidity to a small degree. The power companies are required by the FCC to keep their hash down to minimums. I called my power company and complained about the noise here in my neighborhood. It cost them lots of money to repair all of it 2 or 3 transformers and about a dozen insulators along with a bunch ground wires that were never installed since the 1950's.
     
  7. dave457

    dave457 Well-Known Member

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    Could try a power conditioner, like a Furman M8 or a isobar from tripp lite
     
  8. archjeb

    archjeb Member

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    Not sure how this is going to help. I'm running the radio for this test on battery power and we're still getting *huge* amounts of RFI. What is a power conditioner going to do under this test scenario? Maybe I'm misunderstanding the use case. Please correct me if I am.

    BTW, power company came by (not their RFI expert, just general crew) and he said he could hear RFI on a receiver a half mile away from street. They have a crew coming up this week to investigate...but this looks like we have one piece of the RFI puzzle potentially addressed.
     
  9. Jay Mojave

    Jay Mojave Active Member

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    Good call getting the power company guys out there to look that all over. They have instruments that can locate the noise and they can fix it from years of experience.

    I also had the same type noise coming from a transformer about 200 feet away. I tried to trouble shoot the exact telephone pole and made many pass's up and down the street while listening to a VHF, CB, and a HF radios. But all the radios indicated different levels and such, no pattern could be used to isolate the noisy telephone pole.

    The EMI/RFI Interference books say that the power lines can and will have louder levels of noise on other power poles down the line from the interfering transformer or connection. I suspect the noise is transmitted down the power lines and is transmitted louder at places that have a better impedance of the noise source, based on line length and capacitance. This of course makes isolating the noise 10 times more difficult to isolate and fix. In my EMI/RFI Interference problem the 5th power pole going west from the interfering power pole was the loudest on the CB Band.....

    Another method that sometimes works and I have mentioned this before here, is listening to the noise in your can then hitting the power pole with a sledge hammer, it didn't work for me but other distinguished radio enthuses say it worth a try. No names or call signs will ne identified here to protect the guilty.

    One radio I didn't use was the trucks AM Radio. The power company EMI/RFI guy says it takes out his AM Radio when he is underneath the power pole just across the street from my house. Duh I felt a lot embarrassed, as I over looked this simple method. But he also had a hand held Dish Instrument of some sort that verified his AM Radio RFI findings. The AM Radio could be tuned to frequencies without stations and the noise could be heard, and with local stations on their frequencies the noise would take them out. A good EMI/RFI technique to use, and its simple.

    Hope they are able to fix the EMI/RFI noise problem, as I enjoy a noise free listening to many bands.

    Jay in the Great Mojave Desert
     
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  10. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    We used to do this often when I was in broadcasting. Sometimes people would call the station complaining that they had trouble hearing one of our AM stations and we would arm ourselves with a good GE SuperRadio and a heavy sledge hammer and go knocking on poles. If the noise changed as soon as you hit the pole you had the right one but it it was delayed slightly it was an adjacent pole as the vibrations would travel down the wires. Usually it was a bad or cracked insulator causing the problem.
     
  11. Road Squawker

    Road Squawker Sr. Member

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    Most alarms have some sort of UPS/battery backup power. As do other radiators commonly found in many houses....

    You never mentioned it, but, does the noise level change when it rains?
     
  12. archjeb

    archjeb Member

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    We've had a long dry spell...so I'm waiting for the rain to see if there is a difference in noise.

    As far as the alarm panel, the noise is only when my RS232 cable is plugged in. If I disconnect that, then the RFI stops. this is the biggest noise maker on site. Not sure how to address this one...

    -J
     
  13. archjeb

    archjeb Member

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    ok. Fixed the alarm panel. The ground on the alarm panel was not connected; once I grounded the main board, all the noise from the panel is gone!

    Now another big noise source; the electro-static air cleaner for the furnace blower. Not sure out to fix this one...

    -J
     
  14. BJ radionut

    BJ radionut Supporting Member and 6m addict

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    J: The older air cleaner system I had was noisy also( was the Bug zapper type) I kept good clean filters in place and when operating, I simply turned off the zapper part.
    We just purchased a totally new complete AC/Heat system in June...new air cleaner / 3 filters of different grade...Hippa/charcoal, and microfiber...NO NOISE...YEAAA
    Best I can tell you is keep the zapper coils clean(if that's what you have)...so it does not have to work so hard to stay clean, and replace the screen type filter with a microfiber type and change every season this will help. My zapper caused interference only when it fired...oh yes I cleaned the contacts on the zapper coils and kept good contact grease on them helped a bunch also.
    I also replaced that big capacitor when it was about 10 years old...It Helped also!!!
    Glad your making progress
    Another thought: Turn off your outlets and circuits when possible and pull receptacles and switches out of the wall...Tighten ALL screws and wire nuts (if any) in the boxes and make sure they are all grounded correctly... you would be surprised how many shortcuts some of these rope runner "electricians" make when they do house wiring...Just to save a few wirenuts and good grounding tails...MHO from 40 years as a Journeyman Electrician.
    Listening to your audio file on outside RFI: My ears tell me they will find a bad insulator bushing(s) and at least one loose connection or bad crimp...The change in pitch and amplitude, normally means an ARC.
    GL
    All the Best
    Gary
     
  15. archjeb

    archjeb Member

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    The more I search, the more I find.
    Laptop switcher...big time noise maker.

    I bought this charger that I use for my ATV to keep the battery charged. Huge Noise maker.


    At some point, I need to just go camping and take the HF radio with me :)
     

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