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No RX image rejection

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  • 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 1 of 2 , 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 >
    • unmanagedtn
      I just gave the random wire ant that I am useing a better ground and it seems to have helped ALOT... Will cont. to test... 73 ke4tvv
      Message 2 of 2 , Jan 21, 2008
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        I just gave the random wire ant that I am useing a better ground and
        it seems to have helped ALOT...

        Will cont. to test...

        73
        ke4tvv

        --- In softrock40@yahoogroups.com, "unmanagedtn" <unmanaged@...> wrote:
        >
        >
        >
        >
        > 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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