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Re: [softrock40] 9/16 report on protytype exciter kit

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  • Tony Parks
    Tests continue on the v6 exciter this weekend with measurement of RF output. With a 13 VDC supply the max power output is about 0.6 watts but I have some
    Message 1 of 3 , Sep 17, 2006
      Tests continue on the v6 exciter this weekend with measurement of RF output.  With a 13 VDC supply the max power output is about 0.6 watts but I have some concerns about running at this power level for high dutycycle modes.  The 35 C/watt clip-on heat sink on the 2N3866 output transistor gets hot if the 0.6 watt output level is maintaned for a few 10's of seconds. 
       
      On the positive side the power output was fairly constant over the +/- 20 kHz transmit tuning range from the center frequency and the unwanted sideband was typically down 35 dB or more without amplitude/phase corrections over the 40 kHz tuning range.  (PC soundcard line-out BW may be a limiting factor in frequency coverage with a SoftRock type SDR transmitter.
       
      The only problem on the two exciter circuit boards is the bias adjust pot on the PA board requires CCW rotation to increase ouptut transistor idle current.
       
      Kit shipments to the prototype builder/tester group will start Monday, September 18.  This first built example will be sent to Bill, KD5TFD, for evaluation and to help with PowerSDR software software modifications for phone and CW operation of the v6 exciter. 
       
      Build time for an experienced builder should be about three hours each for the QSE board and the PA board.
       
      Thanks and 73,
      Tony KB9YIG
       
       
      ----- Original Message -----
      From: kb9yig
      Sent: Saturday, September 16, 2006 12:05 PM
      Subject: [softrock40] 9/16 report on protytype exciter kit

      Good Morning All,

      All materials are now in for the prototype v6 exciter kits and the
      first example has been built.

      The first example includes the stack of a 40m SoftRock on the bottom
      with a QSE board plugged on top of the SoftRock and a smaller PA
      board plugged on top of the QSE board. With the clip-on heatsink on
      the TO-39 output transistor the total stack height is just under
      1.88 inches and the stack footprint is 1.5 x 1.9 inches. (The board
      stack would fit nicely on its side within one of the BLT aluminum
      boxes that can be purchased from Doug Hendricks of QRPKITS
      (www.qrpkits. com)

      With the receiver operating the supply is about 60 mA. Supply
      current will be a little over 100 mA when the PA is enabled for
      transmit.

      So far the PPT in function has been checked for muting the SoftRock
      and enabling the QSE. Other QSE circuit functions such as the audio
      amplifiers to buffer line-out from the soundcard to the exciter are
      working properly. The next step will be to try to generate some RF
      output of the PA when quadrature audio input are connected to the
      exciter.

      Kit documentation should be available early next week and kit
      shipments to the prototype builders will be going out early next
      week.

      Thanks and 73,
      Tony KB9YIG

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