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1282Re: Only use PTT and not VOX to switch the PA with Modes with on/off keying !

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  • graham787
    Apr 1, 2012
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      Yes, the com-port PTT option is provided for hard switching of the station, also the CAT link will switch tx/rx, if the radio has this option.

      Important also is to check the ALC, as the audio is pulsed, using ALC can induce a large spike at the start of each pulse, Amtor/Pactor arq where the last mode's to require attention to TX alc function.

      EG: My (all) ft897 have this 'problem' that when the power is set low, using a peak detecting power meter you can measure nearly full power, best to reduce the audio drive to the minimum to prevent over shoot.

      73-G..

      --- In O_P_E_R_A_@yahoogroups.com, "paulwijnand" <paulwijnand@...> wrote:
      >
      > Hello all,
      >
      > A few weeks back I blew my 70 MHz driver-module and PA-transistor while using a VOX operated PA and using Opera (on/off keying).
      >
      > Probably the VOX was not fast enough to switch both input and output coax relais.
      >
      > So the only safe way is to use PTT to switch PA's etc.
      >
      >
      > All is well again, but parts are harder to get nowadays so it took a while, but with a bit more output now hi.
      >
      >
      >
      > 73
      >
      >
      > Paul, PA0OCD
      >
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