help with noise

Discussion in 'General Technical Questions and Answers' started by KE0YRP, Dec 11, 2019.

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  1. KE0YRP

    KE0YRP XML Subscriber QRZ Page

    Hi everyone. I'm new to amateur radio and I'm having difficulty with noise. It's only on certain frequencies, but several frequencies. It's on my Yaesu FTM-400. I've put toroids on my power line to the Yaesu, the antenna, the UPS for my computer, and my refrigerator. I thought turning off the computer worked for a minute, but then I was getting noise again. I can turn up the squelch to like 60-80% to get rid of the vast majority of it, but that doesn't seem like the best solution. Any ideas what I can do? antenna is a Slim Jim role up j-pole. I had it hanging on the wall near a power outlet, but I just moved it to my closet door away from power and there was no change.

    Here are some videos of the noise:

    Anyway, I'm hoping my tech call sign shows up in the ULS today. this is kind of a frustrating start.

    Attached Files:

  2. K7TRF

    K7TRF Premium Subscriber QRZ Page

    A few thoughts:

    - It's always best to take care of noise problems at their source if at all possible rather than trying to fix them at the victim unit (the rig). Sure sometimes well placed chokes can help but it's always better to track down the root cause of the noise and fix it there whenever possible.

    - It could be as simple as a switching phone charger, wall wart power supply, a cordless drill charger out in the shop, etc. So a good starting point is to run your rig off a battery and turn off all the circuit breakers to your home and see if the noise goes away. If it does then turn breakers back on one at a time to figure out which circuit the problem device is connected to and then unplug devices on that circuit until you find the culprit. Yeah, it means resetting things like digital clocks that lack battery backup but it's worth the effort to at least eliminate things inside your own home as RFI sources.

    - If your computer is a laptop then it might still be generating interference if it's running background tasks off its battery. You might try actually moving the computer away from your radio room to see if that helps. Some household devices like some internet routers also have internal batteries which can complicate troubleshooting.

    - The problem might not be inside your own home and if you live in an apartment building or otherwise have very close neighbors it might be coming from elsewhere but again testing your own home and things under your own control is a good place to start.

    - Your antenna system might be contributing to the problem by picking up common mode RFI on the coax feed lines. A choke can sometimes help there as can rerouting coax away from things like CATV and DSL data cables.

    - Unfortunately J poles in the slim Jim or the copper cactus variety are somewhat prone to common mode RF problems on the cables. Sure many hams use them just fine but you might build up a simple 1/4 wave ground plane antenna to see if your symptoms vary, that can be done for a few bucks as they're quick and easy to build. You might also be extra careful about coax routing in terms of things like nearby data cables if you run a J-pole as their design makes them somewhat susceptible to common mode issues.

    Anyway, I'd start by doing a full house audit by turning off all breakers to see if that cures your noise problem. If it does, track down the offending device which is often some kind of power supply or charger but there are many things like plasma TVs that can cause RFI as well.
    KD0CAC likes this.
  3. KE0YRP

    KE0YRP XML Subscriber QRZ Page

    lots of good info there. i might buy a battery and charger and see what happens. would be good for power loss, too. they're just so expensive
  4. WR2E

    WR2E Ham Member QRZ Page

    That rig has 108-136 "air band" I believe. I think that means AM mode?

    What's that noise sound like in AM ?

    What I hear almost sounds like power line noise, strong 60 Hz component but in FM it's hard to tell.
  5. K8ERV

    K8ERV QRZ Member QRZ Page

    I can help you with noise. How much do y0u want?

    TOM K8ERV Montrose Colo
  6. KD0CAC

    KD0CAC Ham Member QRZ Page

    Which is newer - the noise , or the radio ;)
    K7TRF likes this.
  7. K7TRF

    K7TRF Premium Subscriber QRZ Page

    That's deep.....

    Sorta like:

    If a plasma TV is operating in a condo complex and there's no ham rigs around to hear it..... is it RFI? ;)
  8. W9KEY

    W9KEY XML Subscriber QRZ Page

    As others have written above - the most likely source is within your own home. So start by getting a 12 volt battery source to run your radio, listen on a frequency(s) with an obvious noise problem, then shut off the main breaker feeding your house. If the noise disappears, you have isolated it to something inside.

    Then, also switch off all the sub-breakers, re-engerize the main breaker, and selectively turn on each sub-breaker (one at a time) until the noise resumes. In that way, you can quickly identify the home circuit which contains the noise source and track it down (probably to one individual room).

    Of course, if the noise source is outside your home, there's a very different procedure that can be followed. The 2019 ARRL Handbook devotes an entire Chapter (27) to RF Interference and helping you track noise sources - my wife bought me a copy for Christmas last year. A new ham couldn't ask for a better gift!!
    N0TZU likes this.
  9. N0TZU

    N0TZU Platinum Subscriber Platinum Subscriber QRZ Page

    Good advice above. There may be more than one noise source, so if you find one keep going with the breaker test until all have been checked.

    Also, some devices may use batteries like a notebook computer, or backup batteries like a UPS or some cable modems and phones. Make sure those batteries are switched off or removed before doing the AC breaker testing or they will keep operating during the test, leading you astray.
  10. WA0CBW

    WA0CBW Ham Member QRZ Page

    I see you are running fusion in the AMS mode. Because of the noise your radio is switching from fusion digital mode to the FM analog mode between transmissions. Using the DN mode for digital will eliminate the noise. It won't fix the noise problem but at least in the digital mode you won't hear it. I usually only program the A band with fusion digital frequencies and the B band with only analog frequencies. Also, welcome to the Kansas City room.

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