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Re: [softrock40] 50% QSD with four caps

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  • KD5NWA
    Interesting, if my capacitor is too big, I get a big hump in the center of the band-pass, where have we seen that before? When I say lower it, I mean really
    Message 1 of 2 , Oct 28, 2005
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      Interesting, if my capacitor is too big, I get a big hump in the
      center of the band-pass, where have we seen that before? When I say
      lower it, I mean really lower it, in this test to .001uF, signals
      went up, hump in the middle went down,

      Interesting thing to try out, lower the integrating cap, increase the
      filtering in the op-amp to keep trash past 24KHz out of the sound card.

      In a quickie emulation with software you are not familiar with you
      might get results that don't pan out in real life, but it's a strange
      coincidence, might be worth checking out..

      At 02:59 PM 10/28/2005, you wrote:
      >I did a rough approximation, and using a SPDT switch into a
      >capacitor increase the signal by 50% versus a single switch, using
      >two caps and two independent switches increases it by 100% when you add them.
      >
      >Cut the duty cycle to 25% amplitude of the output goes up by roughly 50%.
      >
      >So far 4 caps IQ 25% QSD is the winner in this simple test.
      >
      >Impedance of the source 1000 Ohms, resistor used to limit cap current
      >1000 Ohms, transformer with 1:1 ratio.
      >
      >Using someone else's brand of Spice sure slows you down. Below is a
      >link to a free visual Spice, you create a schematic using a visual
      >editor provided, set the values of the parts, set the frequency of
      >the signal sources, set the simulation length and let her rip. It has
      >some nice multi-winding transformer parts, I liked that.
      >
      >< http://www.catena.uk.com/site/index.htm >
      >
      >I own the professional version of this one from BeigeBag, it is much
      >faster and of course no limits, interfaces to Eagle for board
      >layouts, but they have a free version available, download the "free"
      >not the trial version.
      >
      >< http://www.beigebag.com/ >
      >
      >
      >
      >Cecil Bayona
      >KD5NWA
      >www.qrpradio.com
      >
      >I fail to see why doing the same thing over and over and getting the
      >same results every time is insanity: I've almost proved it isn't;
      >only a few more tests now and I'm sure results will differ this time ...
      >
      >
      >
      >
      >
      >
      >Yahoo! Groups Links
      >
      >
      >
      >

      Cecil Bayona
      KD5NWA
      www.qrpradio.com

      I fail to see why doing the same thing over and over and getting the
      same results every time is insanity: I've almost proved it isn't;
      only a few more tests now and I'm sure results will differ this time ...
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