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Testing I/F Frequencies

Discussion in 'Electronic Basics' started by James Douglas, Feb 12, 2006.

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  1. I am building a 2m/6M radio receiver and studying it's design at the
    same time. I am "lost" when it comes to visualizing how the I/F stuff
    is working. I have "CircuitMaker" and wanted to create a circuit which
    I could simulate and see how it's working but can't find a schematic of
    how to do it?

    I am interested in seeing how by combining two frequencies the output is
    "the sum and difference" etc, and the basic working of Intermediate
    Frequency. BTW the radio is a "dual conversion" type where it takes
    the input freq and converts it to 10.7Mhz then converts again to
    455Khz, etc. If it matters the kit is the Elenco AR-2N6 receiver.

    Thanks!

    Jim Douglas
     
  2. Bob Masta

    Bob Masta Guest

    There is a long history of confusion about this, due to the RF
    world and the rest of the world using "mixing" differently. The
    secret is that in RF, "mixing" really means "multiplication". If
    you multiply 2 sinusoids together, the product has components
    only at sum and difference frequencies of the original inputs.
    This is that same old trig relationship you probably already
    forgot from high school for the product of sines or cosines.

    sin(A) * sin(B) = 1/2 * cos(A-B) - 1/2 * cos(A+B)

    As an aside, this is the same relationship behind Fourier
    analysis. You migth want to check out "Gut-Level
    Fourier Transforms - Everything You Need, You Got In
    High School" at
    www.daqarta.com/eex01.htm

    Best regards,


    Bob Masta
    dqatechATdaqartaDOTcom

    D A Q A R T A
    Data AcQuisition And Real-Time Analysis
    www.daqarta.com
    Home of DaqGen, the FREEWARE signal generator
     
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