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70103Re: [softrock40] Re: What's the most TX power anyone has amplified an RXTX to? Just out of curiosity...

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  • Alan
    Nov 16, 2012
      ----- Original Message -----
      Subject: Re: [softrock40] Re: What's the most TX power anyone has amplified an RXTX to? Just out of curiosity...

      >I have done the following several time to null the TX image when using
      Rocky 3.7 and think it works right but I would be interested in feedback,
      positive or negative.


      I need a lot of thought and experimenting to be sure.
      My first reaction was that it is a pity it needs Rocky. Not too many use it and quite a few find it does not work on their system.

      But the principle does not need Rocky.
      Two separate SDR programs could be used. The one that is intended to be used for transmitting and another one to monitor, temporally
      with the RX soundcard selected.
      Then with your R63 clip, or a switch, the RX SDR program could monitor the TX from the other SDR program.
      Does that sound right?

      73 Alan G4ZFQ

      Rocky 3.7 continues the RX function when in TX with the RXTX Ensemble
      transceiver. The RX antenna connection is open to the antenna path via Q10
      biased off. Moreover, the RX antenna connection over to the QSD circuit is
      shorted to ground by Q11 and the QSD circuit is disabled by the /OE lines
      of U10 being allowed to be pulled to 5 volts with Q9 off.

      What I have done is to clip a lead from the top lead of R63 to circuit
      ground to enable the QSD circuit and get an Rocky RX spectrum display.
      This allows the use of the Rocky TX balance adjustment to "null" the TX
      image. It probably is necessary also to reduce the TX level output to keep
      the RX function from saturating even with the antenna input grounded.

      Tony KB9YIG
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