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Thread: High pitched whining with ADS InstantFM RDX-155 at stronger signal strengths

  1. #1
    Join Date
    Feb 2017
    Posts
    1

    Default High pitched whining with ADS InstantFM RDX-155 at stronger signal strengths

    I have an ADS InstantFM USB tuner hooked up to a Raspberry PI. When I connect an external roof-mounted antennae, I'm getting ~90% signal strength (according to v4l2-ctl run from Linux). Unfortunately I also hear a high-pitched "whine" evident when every there are voices (no whine if there is silence). If I remove the antennae, signal strength drops to ~8%, and although there is more static, the whine is gone. I've tried a shielded USB cable with Ferrites but it hasn't helped. It seems to only happen when the signal is stronger. I also don't hear any whine with the antennae included with the tuner (~40% signal strength). Anyone have any ideas? Thanks!

  2. #2
    Join Date
    Jul 2005
    Location
    Enfield, CT
    Posts
    1,181

    Default

    Just a thought but could there be something in your neighborhood causing it. With the roof mounted antenna, the source could be some distance away. I haven't used mine in a long time but I don't remember any whine and my antenna was an APS-13.
    Mike B.
    Enfield, CT
    -72 30' W/41 59' N
    FN31RX

    Online since 1999 and still going at
    mikesdx.com

    Archives: The Original Mike's TV/FM Page with Tuner Mods and Lots of Old Stuff

  3. #3
    Join Date
    Feb 2006
    Posts
    291

    Default

    If you have a "portable" fm radio, you might try extending the antenna, and walking around the house, to try and pinpoint the source of interference !

    Gary H.

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