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What are the main/most prevalent RFI/emissions sources detremental a ham operator?

Discussion in 'Discussions, Opinions & Editorials' started by AE5DX, Dec 5, 2012.

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  1. AE5DX

    AE5DX Premium Subscriber QRZ Page

    The fish tank thread got me thinking about this.

    I'm sure I have them, every home does, I've heard them and tried to control them, but what could I be missing? I don't necessarily mean the odd bits, but what are some ordinary things that would be in practically every household that I may be overlooking? I don't have a huge problem, but I do hear things I'm thinking I may be able to control if I knew what they were or what they could be.

    I'm aware of:
    Fish Tanks (don't have any)
    Plasma TVs
    Electric motors (blenders etc)
    Fluorescent lighting
    Microwave ovens
    Neon lights
    Laptop chargers
    Dimmer switches?
  2. K9STH

    K9STH Ham Member QRZ Page

    Door bell transformers, these were problematic before a lot of the other sources were even in place.

    Glen, K9STH
  3. KF5FEI

    KF5FEI Ham Member QRZ Page

    Electronic ignitors on furnaces.
    Electronically-controlled variable-speed motors on furnaces, etc...
    Leaky CATV cables, etc...
  4. AE5DX

    AE5DX Premium Subscriber QRZ Page

    O boy, I forgot about those, and I have several potential places to check.
  5. W1RFI

    W1RFI Ham Member QRZ Page

    In no particular order of priority:

    Power-line noise from noisy sources on power poles - the most common report to ARRL

    Grow lights - Some tested at 30 dB FCC limits, S9 almost a mile away - used in various forms of indoor gardening. Farmers generally very concerned that device emits identifiable RF signature and quickly discontinue use of noisy devices. Even in states where legal, farmers concerned about what inter-agency agreements may exist, so they often do not want FCC RFI investigation

    Pulse-width motor controllers, washing machines, air conditioning, furnace. Some fixes found, but not yet known how universal they will be

    Battery chargers, etc. Some have been tested as much as 30 dB over FCC limits. In marinas, HF radio virtually destroyed.

    Plasma TV - jury still out. Some are noisy, but others clearly not, so it is not necessarily the plasma technology itself. ARRL started to work with a ham with a cooperative neighbor on trying filters, but neighbor stopped cooperating and ham feels he wants to move anyway.

    LED bulbs - so far so good on the ones from major box stores, but a few imports very noisy. ARRL planning article to document recent test results.

    CFLs - ditto, but no article.

    Miscellaneous switching supplies - most switchers seem clean enough but ARRL has some reports.

    If hams do have reports of specific model numbers causing >S7 interference from house next door, please send reports to It is possible for "legal" devices to cause interference in hams' own homes, but noise levels in-house >S9 or so may be suspect.

    I'll see if Mike Gruber can add some to the list.

    Ed Hare, W1RFI, ARRL Lab
  6. K7WFM

    K7WFM Ham Member QRZ Page

    Second the CFL bulbs. Worst offenders at this QTH.
    Last edited: Dec 5, 2012
  7. AE5DX

    AE5DX Premium Subscriber QRZ Page

    Now see, I try to do the "green" thing and now I've got these dang things all over the house.
  8. AE5DX

    AE5DX Premium Subscriber QRZ Page

    Thanks, Ed. I have one LED bulb. I bought it out of curiosity, says it'll last for 13 years or so. I've marked my calendar.
  9. K7WFM

    K7WFM Ham Member QRZ Page

    Right? Not to mention if they break, we need a hazmat crew called in. ;)
  10. AE5DX

    AE5DX Premium Subscriber QRZ Page

  11. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    I'd add, from my own experiences:

    -Electric fences and their transformers/wiring/connections...can be horrible. Obviously this is a more "rural" thing, but I've heard electric fence noise more than a mile away and when I finally zeroed in on it (driving around with an AM radio), turns out the lady who owned the small horse ranch didn't even know she had it turned on! We found the switch in her barn, flipped it off, and the 20/S9 noise all went away. I convinced her to leave it unplugged.

    -The small power supplies used to power many small electronics items, some of which are turned on 24/7; I've found really bad noise generation from those used on networking routers. Pull 'em out, replace with a small battery, all the noise goes away. The ones powering laptop computers and such seem to be much better, but some may be noisy.

    -Not "generators" as much as "unintended receptors" of interference have been some of my GFCI outlets. Even some brand new ones; seems to vary with brand and model, and probably length of wiring, outlet location and other things. But I've had to experiment to find ones that don't "trip" off when I transmit with high power on certain amateur bands.
  12. AB2T

    AB2T Ham Member QRZ Page

    in cars, windshield wiper motors. Often on FM repeaters I would hear the high-pitched whine of wipers going back and forth.

    73, Jordan
  13. W8IXY

    W8IXY Premium Subscriber QRZ Page

    I have been fighting 20 over 9 noise on 75 meters from the neighbor's AT&T U-Verse TV connection. I can hear the "hash" from the high end of the AM BCB, up to almost 5 mHz, but its most concentrated on 75, where most of the U-Verse data is carried. I called AT&T service and complained. Their response was pretty much "tough luck". I asked if they could put the service underground or run a shielded cable from the pole to the neighbor's house. The CSR actually laughed and said "We don't do that".

    I filed a complaint with the FCC, although I doubt much will come of that.

    My 75 meter inverted L runs parallel to the U-Verse drop connected to the neighbor's home, and is about 30 feet away. My neighbors are good people and I don't want to disrupt their TV enjoyment. However, I think I may step up my 75 meter activity and see if AT&T needs to shield their cable from MY 600 watts of RF.

    My TV/internet/phone cable comes in on coax, causes no interference to me, and I cause no interference to my TV/internet/phones in my home.

    Anyone out there with U-Verse stories, especially what kind of RF may cause interference TO U-Verse - for informational purposes only, of course.

    Ted W8IXY
  14. AF6LJ

    AF6LJ Premium Subscriber QRZ Page

    I second U-Verse a neighbor had the service and tore up twenty meters....
    For some reason not longer after I started meeting up with a group on seventy five meters the repair man was over there three or four times and the noise is gone.
    Makes me happy....
  15. N0SYA

    N0SYA Ham Member QRZ Page

    I'm guessing the worst and most common are switchers and bad street lamps or pole insualtors/surge zorbers.
  16. AE5DX

    AE5DX Premium Subscriber QRZ Page

    When I get a chance (sigh) I'm going to take my old trusty AM transistor radio for a walk, first around my place, just to see what's what. I also have a few HTs, 2m, 70cm and 1.25cm, a tape-measure yagi and a RS handheld scanner... and do the ol' turn-off-the-main-breaker trick.
  17. G0GQK

    G0GQK Ham Member QRZ Page

    If you have an electric toilet, check that !

    Mel G0GQK
  18. KU7PDX

    KU7PDX Ham Member QRZ Page

    Now I have to clean the coffee off my computer. This is the best thing I read today! :D
  19. WU8Y

    WU8Y Ham Member QRZ Page

    Totally opposite here - CFLs are super-quiet.
  20. WU8Y

    WU8Y Ham Member QRZ Page

    Just like regular fluorescent bulbs, all over the place. More FUD.
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