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13432Re: [tracker2] OT2 Audio Out Questions (Decoupling and Deviation)

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  • James Ewen
    Jan 6, 2012
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      On Fri, Jan 6, 2012 at 12:01 PM, Edward <egiandomenico@...> wrote:

      > Question 1: The OT2 has a 0.1uF decoupling capacitor on the "Audio Out" line. Is that correct?

      Yup.

      > Question 2: In addition to the decoupling capacitor there is a jumper "HI" that allows
      > you to select use of either a A.) 100k resistor or B.) 100k resistor in parallel with a 30k
      > (~23K). If I understand the circuit correctly the resistor(s) are used to control the voltage
      > of the signal being sent to the transmitter (which in turns will control the deviation
      > of the output signal). Is that correct?

      Nope... the HT jumper changes the loading on the line... Some HTs look
      for a load on the audio line when PTT is asserted, some HTs need a bit
      more load than others... The audio (and it's deviation) are an AC
      signal superimposed on the DC on the circuit. The AC passes through
      the decoupling capacitor while the DC is being blocked. Deviation of
      the audio signal is controlled elsewhere, which in the OT2 is in the
      software.

      --
      James
      VE6SRV
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