Massive Interference on 6 meters.

Discussion in 'VHF/UHF - 50Mhz and Beyond' started by KB5IJ, Feb 5, 2015.

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  1. KB5IJ

    KB5IJ XML Subscriber QRZ Page

    After not using 6 meters for several months, I've been active on 6m again now that there have been some decent openings in recent weeks. Except now I have this massive interference that sounds like electrical buzz/sizzle that hits me with an S7, 24 hours a day, 7 days a week. I never had any noise at all before. The interference starts at about 49.400, peaks across the SSB portion of 6 meters, then dies away by 50.700. Not sure if that's the result of the interference being centered on that part of the band, or if my antenna is just that narrow-banded, but I have no problems on any other bands, HF thru UHF. I've been unable to trace it to anything in my house, so I assume it's coming from a neighbor, but I'm curious.... Does anyone know of any particular devices that would destroy 6 meters, and not cause interference to any other bands? Is it possible the problem could be something in my setup- grounding, etc.?
  2. ZL1UZM

    ZL1UZM Ham Member QRZ Page

    This happened to a friend of mine. It turned out to be a faulty WiFi router.
  3. W1GCI

    W1GCI Ham Member QRZ Page

    If you have a rotatable antenna, can you see if it peeks in a certain direction? My tower is about 100 feet from the house and I can easily determine if a noise is coming from the house simply by rotating the beam toward or away from the house. Also, try removing the coax from the antenna and putting in its place a small wire. If the noise level still remains at about s7 or even gets louder, it's definately something in your shack or house.
  4. KB5IJ

    KB5IJ XML Subscriber QRZ Page

    I'm just using a loop antenna, so I can't do any direction finding at this point. I can tell you this much: it is quiet with just the center pin of the coax connected, then connecting the shield brings the S7 noise. Interesting about the WiFi router, I will look into that.
  5. AA9G

    AA9G Ham Member QRZ Page

    What kind of loop? If you mean the small mag loop those are excellent for DFing noise.
  6. KB5IJ

    KB5IJ XML Subscriber QRZ Page

    The antenna is a Par OA-50.
  7. AA9G

    AA9G Ham Member QRZ Page

    Ok. I don't reckon that is very portable nor has much of a null. So, can you make a recording and/or a screen shot of the interference?
  8. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I'd say the reason the noise peaks where it does is because that's where your antenna is resonant. The noise source itself is very unlikely to have such a peak in its radiation profile.

    The Omniangle loop actually could be used for direction-finding if you flip it vertically and put it on a rotator; it will be bi-directional with two nulls that can be used for direction finding. However, such noise sources are often very broadband and using almost any kind of "portable" (hand-held, battery-powered) receiver with any kind of loop can often be very helpful.

    Zillions of wideband noise sources out there. One particularly annoying one is the lights "growers" use for their indoor plant farms. Usually those plants are ones they're not supposed to be growing.:p But many kinds of lightning, neon sign transformers, electric fence transformers, battery chargers, motor speed controls, etc, etc can generate RFI that carries for a long distance.
  9. KW4EK

    KW4EK Premium Subscriber QRZ Page

    I was going to suggest the same. When I tune my antenna it is very easy to see the point of maximum resonance on my SDR display when viewing 1MHz, or more, of the band at once (the hump is made visible by the broadband background noise). The hump around the resonant point is clearly visible and slowly, and smoothly, drops off in sensitivity as you move towards each end.
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