HELP: Need help with SA602 Mixer

Discussion in 'Wireless & RF Design' started by hamopp, Dec 28, 2011.

  1. hamopp

    Thread Starter Active Member

    May 13, 2009
    68
    1
    Hi All
    I'am thinking of using a sa602 chip, not used one before:eek:, To down-mix 9Mhz to 455Khz for am\fm detection.

    Not sure if i have got things right with IC1, i have a crystal of 8.545Mhz connected as the osc, pin 4 of IC1 go's to a 455Khz filter,
    then on to a TCA440 AM IF chip (not sure if thats a good chip to use).

    For FM, use another 455Khz filter diode switched to a FM Detector with squelch (not sure what chip to use here).

    For SSB, use another sa602(IC2) with the input coming from a cascade MC1350 9Mhz if amp with agc, and feeding the BFO Osc (8.985Mhz and 9.0015Mhz) into pin 6, and hoping that SSB Audio will come out of pin 4.

    Is this the right way to use the SA602 chip ??
    Thanks for any help
    Hamopp.

    This is the Circuit:
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,347
    Hello,

    I think the circuits are quite fine.
    Only the capacitors at the x-tal oscillator in the datasheet have a 1:2 ratio (1 accross pin 6 and pin 7 and 2 from pin 7 to ground).
    (make C3 47 pF and C4 100 pF).

    Are you having trouble with the circuits?

    Bertus
     
    Last edited: Dec 29, 2011
  3. hamopp

    Thread Starter Active Member

    May 13, 2009
    68
    1
    Hi
    From what i find on the net the way i have done is right, but not 100%

    No i have not tested the circuits (602's not arrived yet!).

    With IC2, is this the right way to use this chip ?, i have used a SBL-1 mixer before as a product det, but they need more osc drive (+7dB).

    I have a 9.0015 and 8.985Mhz crystal BFO built, and wanted to know if injecting this into pin 6, and injecting 9Mhz from the last ift into pin 1, would SSB Audio come out of pin 4, or would i need to use a prod det like the MC1496 ??

    Any ideas on a 455Khz am\fm Detector circuit ?

    Thanks
    hamopp
     
  4. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,347
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