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Re: QR2S - Osc freq too high

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  • ltj_designs
    I m having a difficult time pulling the oscillator down to 10.140 Mhz. With variable cap 138 set at maximum C, I added some additional capacitors. Here are my
    Message 1 of 10 , Jun 30, 2010
      I'm having a difficult time pulling the oscillator down to 10.140 Mhz. With variable cap 138 set at maximum C, I added some additional capacitors. Here are my results:

      Added
      Cap Frequency
      0 pf 10,140,435 Hz
      10pf 10,140,408 Hz
      37pf 10,140,345 Hz

      "Frequency" setting is at 0





      --- In GenesisRadio@yahoogroups.com, "Nick" <nick@...> wrote:
      >
      > Very good - you are (alomst) spot on.
      > If you have installed fix value cap in place of C138 then replace it with
      > trimmer (this is the third, spare trimmer
      > whic was included for that purpose).
      > Alternatively just add 5-8pF in parallel to C138.
      >
      > Happy QRSSing!
      >
      > 73 Nick VK1AA
      >
      >
      > >Here are the frequencies I see with C138 set for lowest frequency. These
      > >are accurate to well under 1 Hz.
      >
      > FREQ
      > Setting Measured (hz)
      > 0 10,140,436.16
      > 10 10,140,447.88
      > 50 10,140,502.62
      > 100 10,140,628.24
      > 128 10,140,700.93
      > 200 10,140,879.27
      > 255 10,141,014.95
      >
      > I think I would like the lowest frequency at or below 10.140 Mhz.
      >
      > Oven Temperature set at 45.
      > Measured temperature of Q12 using simple thermistor digital thermometer:
      > 42.7 degC
      >
      > Andy
      >
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