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Re: Symmetrical display on Rocky

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  • Rob Campbell
    Thanks to all who replied, your advice was most helpful. Sorry it s taken so long to post back but work/home pressures have left no time to play with radios
    Message 1 of 6 , May 30, 2006
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      Thanks to all who replied, your advice was most helpful. Sorry it's
      taken so long to post back but work/home pressures have left no time
      to play with radios :-(

      The good news is that my SR6 works fine with Winrad on a 733MHz P3
      machine at work - no problems with T1 or the 3253 switch. It doesn't
      show the symmetrical display problem I've got at home and a little
      trimming of the I/Q channel skew settings gave me around 70dB image
      rejection.
      The bad news is that probably means my old PC with the SoundBlaster
      Live! doesn't have enough steam to handle SDR work. I'll have to see
      about getting something a bit more powerful.

      I've got some more questions/comments but I'll keep those for
      another thread.

      Thanks,
      Rob GM6OQN

      --- In softrock40@yahoogroups.com, "Rob Campbell" <gm6oqn@...> wrote:
      >
      > Hi,
      >
      > I read messages 4658/9 and found now that I've got my SR v6
      working
      > I have a similar problem. Doing the crudest of tests (transmitting
      > into a dummy load with an 18-inch piece of wire on the SR antenna
      > input) I can see/hear my signals on 40m but the display is
      > symmetrical about the centre frequency.
      > I've checked that I'm connected to the Line-in jack, both left and
      > right are correct to the documentation and I get a hum from the
      > appropriate speaker if I touch the I/Q leads when Rocky is
      stopped.
      > With a DMM connected to the outputs in turn I see signals of the
      > order of 20-80mV rms depending on the output power I use (test as
      > above) so both op-amps appear to work. I had the SR on a scope at
      > work and the clocks appear correct at the two vias in the centre
      of
      > the PCB i.e in quadrature. Continuity to the S0 & S1 pins of the
      > FST3253 is OK and no shorts.
      >
      > Where should I look next? T1 windings? A damaged 3253? Rocky setup?
      >
      > PC is an ancient 400MHz AMD K6-2 with an equally ancient SB Live!
      > just to get things working (need to get a USB card for my laptop
      > and/or software & 96k card running on my Linux machine - both of
      > these are 1.1GHz). How do I use the +/- 1-bit shift control for
      the
      > SoundBlaster?
      >
      > Rob, GM6OQN
      >
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