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Re: RXTX V6.2 20/30M

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  • n2pk2001
    Hi Jim, Glad to hear the build went well. ... Indeed, still going strong at 5 PM ET on 20m CW. Just worked OK1TN with 1 watt. 73, Paul, N2PK
    Message 1 of 3 , Sep 1, 2007
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      Hi Jim,

      Glad to hear the build went well.

      >DX coming through all morning,

      Indeed, still going strong at 5 PM ET on 20m CW.

      Just worked OK1TN with 1 watt.

      73,
      Paul, N2PK
    • n2pk2001
      Hi Jim, OK on the DX. BTW, why you used 74ACT74 s instead of the specified 74AC74? The ACT74 may clock higher but it s not an issue at 56 MHz. What I m
      Message 2 of 3 , Sep 2, 2007
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        Hi Jim,

        OK on the DX.

        BTW, why you used 74ACT74's instead of the specified 74AC74?

        The ACT74 may clock higher but it's not an issue at 56 MHz.

        What I'm concerned about is that the ACT74 input threshold
        is about 1.4 VDC vs about 2.5 VDC for the AC74. The R58/R59
        resistor divider was chosen to match the AC74 input threshold.

        By leaving the R58/R59 divider the same with the ACT74, the
        symmetry is reduced and the negative pulse width is narrowed
        which actually aggravate the clocking.

        If you change R58/R59 to match the ACT74 threshold, then the
        negative input excursion may go below ground which isn't good
        either.

        73,
        Paul, N2PK
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