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Tecsun PL-600 TA2057 AM FM Receiver Chip Circuitry Question

Discussion in 'General Electronics Discussion' started by radiotek, Sep 22, 2017.

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  1. radiotek


    May 31, 2011
    Tecsun PL-600 TA2057 AM FM Receiver Chip Circuitry Question

    It looks to me like there are two possible signals that come off of pin 18 of the TA2057 AM FM receiver chip. If pin 18 is held low it enables the AM IF out and if pin 18 is high it enable AM detector out signal which I can comprehend but what is confusing is all of the additional circuitry doing including the two MOSFETS IQ13 and IQ14.

    It would be appreciated if any engineers out there could explain the function of all this additional circuitry after pin 18.

  2. davenn

    davenn Moderator

    Sep 5, 2009
    your response in that other forum......
    you obviously misunderstood the reply by user - Usually Lurking

    that circuitry is actually hanging off pin 17, not 18 and is to do with the stereo detection

  3. radiotek


    May 31, 2011
    If you follow the path from pin 18 you will see that it leads to 1Q14 the first MOSFET.

    Maybe I was unclear with my question. I basically wanted to know what the purpose of the MOSFETS were ?

  4. 73's de Edd

    73's de Edd

    Aug 21, 2015
    SIR radiotek . . . . .

    Can you give me access to the whole schematic or model # and brand.
    Initially and as a preliminary thought, I am certainly seeing that external slave circuitry as being related to being used to switch in the beat oscillator . . . with it using a transistor and a 458 khz xtal oscillator xtal .
    This then lets your mosfets (used as solid state switches) switch up and inject the the BFO osc RF via the C2 coupling capacitor to be able receive SSB reception in the receivers AM mode.

    All hams ALMOST EXCLUSIVELY use SSB in these times

    73's de Edd
    Last edited: Sep 23, 2017
  5. radiotek


    May 31, 2011
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