tuner squeel

Discussion in 'Wireless & RF Design' started by PRS, Jan 31, 2010.

  1. PRS

    Thread Starter Well-Known Member

    Aug 24, 2008
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    What is causing those squeels when your near a station but not right on it?
     
  2. ELECTRONERD

    Senior Member

    May 26, 2009
    1,146
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    With my HF radio equipment, I've often heard these pure oscillations when I tune through any of the bands. I believe that this is caused when people are tuning their radios. But this is HF, what frequency are you referring to?

    Austin
     
  3. Wendy

    Moderator

    Mar 24, 2008
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    AM or FM? I'm betting AM. It has to do with sidebands being mixed (heterodyned) incorrectly.
     
  4. PRS

    Thread Starter Well-Known Member

    Aug 24, 2008
    989
    35
    Electronerd, I think the squeel I'm talking about is common to most Am broadcast band radios. That's the frequency I am refering to. Also, commercial Am is the mode of modulation I am refering to.
     
  5. PRS

    Thread Starter Well-Known Member

    Aug 24, 2008
    989
    35
    Bill, you're right, it's AM. But I'm not sure what you mean by incorrect mixing.
     
  6. Wendy

    Moderator

    Mar 24, 2008
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    Think about how an AM dial is organized, every 10Khz there is a station, some far, some close. If you tune a dial between two stations their frequencies will heterodyne together, but not as a stable sound. Hence the squeal.

    Visualize two AM frequencies on a spectrum graph and you get the idea.
     
  7. PRS

    Thread Starter Well-Known Member

    Aug 24, 2008
    989
    35
    Thanks. That makes sense.
     
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