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Re: how about a SoftRock with build in audio processor?

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  • Bob Zinn
    ... yet. ... Good!!!! ... I tried a different laptop which seems to have a much better sound card . Almost no hump in the middle, and YES, you are [of
    Message 1 of 41 , Jan 1, 2008
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      --- In softrock40@yahoogroups.com, k5nwa <k5nwa@...> wrote:
      >
      > At 12:41 PM 1/1/2008, you wrote:
      >
      > >That board was the 'inspiration' but not necessarily the way to go.
      > >
      > >You are right, so, a 24 bit ADC would be a better way to go.
      > >
      > >The center hump seems to be from the Local oscillator [at least I can
      > >hear it strongly radiated in a nearby receiver], some good shielding
      > >may also be needed. Of course, I don't have the softrock in a case,
      yet.
      > >
      >
      > During late winter (I need to recover from expenses and build up my
      > slush fund), around March I will be doing a group buy of several
      > components. One of the devices will be a fairly good quality 24 bit
      > A/D and D/A chip that will be less than $6, that chip and a PIC
      > 18F2550 will make a very nice 24 bit USB sound board for little
      > money. Right now I can't recall the name of the manufacturer but I
      > have it down "somewhere".

      Good!!!!

      >
      > Unplug the SoftRock and power it off, you will still see the hump,
      > it's due to the A/D in your sound card not reading 0 when it's
      > getting 0V for an input, a FFT of a small DC voltage will give you a
      > large signal at 0Hz. some of it is due to ground loops. The QSD
      > detector is deaf to it's LO frequency which produces a steady DC
      > output due to the signal being capacitively coupled in it's output
      > and amplifiers.

      I tried a different laptop which seems to have a much better 'sound
      card'. Almost no 'hump' in the middle, and YES, you are [of course]
      right, it MUST be deaf to its own LO.

      I will be looking forward to March'ing together.

      > Cecil
      > K5NWA
      > www.softrockradio.org www.qrpradio.com
      >
      > "Blessed are the cracked, for they shall let in the light."
      >
    • unmanagedtn
      On pin 1 (top left of U8) I have 4.9 volts! :( and on pen seven I have 2.48 volts :) I am testing things out now and had to pull this thread and info out of
      Message 41 of 41 , Jan 21, 2008
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        On pin 1 (top left of U8) I have 4.9 volts! :(
        and on pen seven I have 2.48 volts :)

        I am testing things out now and had to pull this thread and info out
        of another topic....

        Tony does this mean that U8 needs to be replaced?

        I see the same things on both sides.

        73
        ke4tvv


        > No RX image rejection results when one of the I / Q signals from the
        RXTX board is not getting to the stereo soundcard line-in input. The
        problem could be on the RXTX board, in the cable or at the soundcard.
        Also, if I and Q signal lines are shorted together no image rejection
        will be the result.
        >
        > There have been a few cases of U8 failing when the RXTX board I / Q
        output signals were connected to a soundcard when an AC voltage
        difference existed between the soundcard ground and the ground on the
        RXTX board. Please check the DC voltages at pins 1 and 7 of U8 to see
        if the two pins are still at about 2.5 volts with reference to circuit >
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