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Re: Daughterboard won't oscillate on 40.5MHz

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  • Dave
    Squishing the turns as close as I could get them got 40.50MHz to oscillate. My battery has discharged to about 11.5V, dropping the p-p output voltage a bit.
    Message 1 of 4 , Sep 2, 2007
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      Squishing the turns as close as I could get them got 40.50MHz
      to oscillate. My battery has discharged to about 11.5V, dropping
      the p-p output voltage a bit. 56.2 is now 2.25V and 40.5 is
      about 1.8V (it takes a moment for 40.5 to reach stable p-p
      voltage).

      L100 has the correct number of 12 turns (12 passes through the
      toroid). Unsquished it measured 0.47uH and squished it measures
      0.51uH (both a bit higher than the schematic-stated 0.43uH).
      Perhaps I will try changing from 12 to 13 turns which should give
      me about 0.55uH measured unsquished, but I suppose that might kill
      the 56.2 oscillation.

      Dave, WA3OFF
    • Dave
      ... I wound 13 turns (unsquished) on another T25-6 core I had in stock and measured it at 0.54uH. With the supply now at 11.4V, 40.50 now has output of 2.3V
      Message 2 of 4 , Sep 2, 2007
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        > L100 has the correct number of 12 turns (12 passes through the
        > toroid). Unsquished it measured 0.47uH and squished it measures
        > 0.51uH (both a bit higher than the schematic-stated 0.43uH).
        > Perhaps I will try changing from 12 to 13 turns which should give
        > me about 0.55uH measured unsquished, but I suppose that might kill
        > the 56.2 oscillation.

        I wound 13 turns (unsquished) on another T25-6 core I had in stock
        and measured it at 0.54uH. With the supply now at 11.4V, 40.50 now
        has output of 2.3V p-p (and comes up to that almost immediately) and
        56.2 has 2.2V p-p, so I think I'll call it ready to install.

        Thanks for the help.

        Dave, WA3OFF
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