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interface to a 455 KHz IF

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  • frank carcia
    Hi All, It would be cool to have an interface directly off a 455 KHz IF so sdr demodulation could be interfaced with the typical analog receiver. wa1gfz
    Message 1 of 6 , Nov 29, 2005
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      Hi All,
      It would be cool to have an interface directly off a 455 KHz IF so sdr
      demodulation could be interfaced with the typical analog receiver.
      wa1gfz
    • KD5NWA
      A issue to consider is spurs in the center of the pass-band, you would want to not have the center of the band at 455KHz but either 12KHz lower or higher. In
      Message 2 of 6 , Nov 29, 2005
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        A issue to consider is spurs in the center of the pass-band, you
        would want to not have the center of the band at 455KHz but either
        12KHz lower or higher. In that way you can have a 455 IF with +-
        10KHz of space with no spurs. You can also reduce the amount of spurs
        by powering the unit from an independent wall wart, and my making
        minor mods to the SR-40 to isolate the input circuit from the SR-40 ground.

        Leakage of the SR-40 oscillator will also be a problem specially if
        you put the SR-40 inside the radio.

        At 02:38 PM 11/29/2005, you wrote:
        >Hi All,
        >It would be cool to have an interface directly off a 455 KHz IF so sdr
        >demodulation could be interfaced with the typical analog receiver.
        >wa1gfz
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        >Yahoo! Groups Links
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        Cecil Bayona
        KD5NWA
        www.qrpradio.com

        "Windows the most successful software virus ever"
      • Tony Parks
        I have wondered about using the BFO output of an existing receiver as the oscillator source with a v5.0 SoftRock used in IF applications. Tony KB9YIG ... From:
        Message 3 of 6 , Nov 29, 2005
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          I have wondered about using the BFO output of an existing receiver as the
          oscillator source with a v5.0 SoftRock used in IF applications.

          Tony KB9YIG

          ----- Original Message -----
          From: "frank carcia" <carcia@...>
          To: <softrock40@yahoogroups.com>
          Sent: Tuesday, November 29, 2005 3:38 PM
          Subject: [softrock40] interface to a 455 KHz IF


          > Hi All,
          > It would be cool to have an interface directly off a 455 KHz IF so sdr
          > demodulation could be interfaced with the typical analog receiver.
          > wa1gfz
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          >
          >
          >
          >
          > Yahoo! Groups Links
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        • FRANCIS CARCIA
          True a simple quad hybrid to generate the 2 lo signals 90 degrees apart. Most mil receivers limit the bfo range plus and minus 8 KHz so that would be the limit
          Message 4 of 6 , Nov 29, 2005
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            True a simple quad hybrid to generate the 2 lo signals 90 degrees apart. Most mil receivers limit the bfo range plus and minus 8 KHz so that would be the limit of IF intot he sound card.

            Tony Parks <raparks@...> wrote:
            I have wondered about using the BFO output of an existing receiver as the
            oscillator source with a v5.0 SoftRock used in IF applications.

            Tony KB9YIG

            ----- Original Message -----
            From: "frank carcia" <carcia@...>
            To: <softrock40@yahoogroups.com>
            Sent: Tuesday, November 29, 2005 3:38 PM
            Subject: [softrock40] interface to a 455 KHz IF


            > Hi All,
            > It would be cool to have an interface directly off a 455 KHz IF so sdr
            > demodulation could be interfaced with the typical analog receiver.
            > wa1gfz
            >
            >
            >
            >
            >
            >
            >
            > Yahoo! Groups Links
            >
            >
            >
            >
            >
            >
            >

          • Mike WA8BXN
            A few thoughts --- Spurs may be a minor problem due to a much greater signal level being input to the SR-40. I would be concerned about stability of the analog
            Message 5 of 6 , Dec 1, 2005
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              A few thoughts ---
              Spurs may be a minor problem due to a much greater signal level being input
              to the SR-40.

              I would be concerned about stability of the analog receiver and bandwidth of
              the IF. You probably would want to take the 455 KHz signal right from the
              pixer before any IF amplifiers.

              73 - Mike WA8BXN
            • FRANCIS CARCIA
              I have a very modified Racal RA6830 that I would use. It has an AUX 455 KHz channel 16 KHz wide. I had it interfaced to a mot dsp56303 EVM with an I/Q
              Message 6 of 6 , Dec 2, 2005
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                I have a very modified Racal RA6830 that I would use. It has an AUX 455 KHz channel 16 KHz wide. I had it interfaced to a mot dsp56303 EVM with an I/Q interface and found the board a pain to reconfigure every time I wanted to change bandwidths. Sound card would be a lot easier than reloading filter constants. I not ready to delete all the analog hardware yet.  It a shoot out the DSP had a ever so slight advantage under high noise conditions. gfz

                Mike WA8BXN <hubby2k@...> wrote:

                A few thoughts ---
                Spurs may be a minor problem due to a much greater signal level being input
                to the SR-40.

                I would be concerned about stability of the analog receiver and bandwidth of
                the IF. You probably would want to take the 455 KHz signal right from the
                pixer before any IF amplifiers.

                73 - Mike WA8BXN



                YAHOO! GROUPS LINKS





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