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SAA1057 and the minimum frequency of the external oscillator.

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  • 27. March 2007 at 9:33 #11020 Reply
    om2amb
    Participant

    Good morning.

    I have a question about the minimum frequency of the external oscillator for the SAA1057? v datasheete je pisana len maximalna. I found a receiver on the net with an external 1Mhz oscillator and they achieved a step of 250Hz, but I would need a step of 100hz (receiver on 80m)

    I wonder if the frequency of 400kHz will not be too small for the internal logic (it will not bother the phase curtain, but will it not bother the input part of the control word)

    Marek

    27. March 2007 at 11:49 #11851 Reply
    Anonymous
    Guest

    I looked at the datasheet and right in the introduction it is written that the input frequency for AM is from 512khz to 30Mhz and the stepping is after 1khz or 1.25khz.

    Tu je ten datasheet:
    http://www.peter-geisler.de/datasheet_SAA1057.pdf

    27. March 2007 at 13:16 #11852 Reply
    om2amb
    Participant

    zawin: that step is when using a 4Mhz crystal and nowhere in the datasheet is it mentioned that I could not use another.

    eg here: http://amber.feld.cvut.cz/user/pokorny/bpdp/RX_80_20.pdf
    is used in receiving na 80 and 20m with steps of 250Hz/500Hz

    but as I looked, I can't do it that way because with a step of 100Hz I can't get to the 80m band (3.2Mhz is max) and since it is a direct mixing receiver, I have to master the frequencies of 3.5-3.8Mhz, just to get used to the step of 125Hz

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