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Re: t4xc sidetone / VOX problem

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  • Martin
    Message 1 of 2 , Feb 7, 2007
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      Martin a écrit :
      > Hello
      > i am mix up with this t4xc problem.
      > I have a problem with the sidetone being present in the CW-mode all
      > the time the VOX is active.
      > I made the test voltage and resistance on tube.
      > Only suspect thing is
      > PIN 7 of the 6FQ7
      > read -0.73V instead of - .36 and 1.04 megohms
      > instead of 2 meg
      > R68 ok
      > R69 ok
      > R71 ok
      >
      > any idea ?
      > Martin
      > VE2EDK
      >
      >
      >
    • Garey Barrell
      Martin - The tone is keyed by CR15. CR15 is either forward biased to short circuit the audio tone to ground, or reverse biased to allow the tone to pass
      Message 2 of 2 , Feb 7, 2007
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        Martin -

        The tone is "keyed" by CR15. CR15 is either forward biased to "short
        circuit" the audio tone to ground, or reverse biased to allow the tone
        to pass to V9b, by DC bias.

        Try paralleling another capacitor across C107. When this capacitor
        dries out, the ESR goes up and the AF tone from V9a is coupled via the
        B+ line over to V9b, effectively bypassing the control of CR15.

        Let me know!

        73, Garey - K4OAH
        Atlanta

        Drake 2-B, 4-B & C-Line Service Supplement CDs
        <www.k4oah.com>



        Martin wrote:
        >
        >
        > Martin a écrit :
        >>
        >>
        >> Martin a écrit :
        >>> Hello Garey
        >>> i am mix up with this t4xc problem.
        >>> I have a problem with the sidetone being present in the CW-mode all
        >>> the time the VOX is active.
        >>> I made the test voltage and resistance on tube.
        >>> Only suspect thing is
        >>> PIN 7 of the 6FQ7
        >>> read -0.73V instead of - .36 and 1.04 megohms
        >>> instead of 2 meg
        >>> R68 ok
        >>> R69 ok
        >>> R71 ok
        >>>
        >>> any idea ?
        >>> Martin
        >>> VE2EDK
        >>>
        >>>
        >>
        >>
        >
        >
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