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16592Re: Daughter board on SR 15/17m

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  • mikecol2
    Dec 1, 2007
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      > no I don't get around 84450KHz the most i got was 79230 UNSTABLE so
      I guess
      > there must be an error somewhere.
      > I got this reading with 7 turns when i reached 6 turns the oscillator
      > stopped.
      > The total amount is 9 turns... As I don't have an impedance meter I
      am done.
      > Can your give me some more suggestions.

      Hi Jose,

      I was playing around with the 15m/17m oscillator board (N2PK) today
      and have some data for you.
      With the suggested 9 turns I measured .26uH on my AADE L/C meter.
      With that coil (L100) in place my oscillator measured:
      w 1800 pf cap: 71Mhz
      w 1500 pf cap: 71.4Mhz
      w 470 pf cap: 72.7Mhz
      w 100 pf cap: 76.4Mhz
      w 28.06 XTAL: 84.25Mhz
      w 28.224 XTAL: 84.73Mhz

      The cylinder 28Mhz XTAL Tony gave us to try didn't oscillate with the
      stock 9T coil.

      Just to compare my 20m/30m: it resonated at about 46Mhz. Using the
      tank circuit of .43uH (spec'ed) with the 12pf the calculated
      additional Cexternal is about 15pf.
      If you add this Cexternal of 15pf to the 6.8pf and .22uH for the
      15m/17m circuit it calculates out to a resonant freq of 73Mhz. This
      matches quite well to what I measured using the caps instead of the XTAL.

      Hope that help some. Summary: mine works fine with the stock 9T

      73, Mike Collins KF4BQ
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