Loading ...
Sorry, an error occurred while loading the content.

Re: Crystals & Oscllators [Maybe more than you wanted to know]

Expand Messages
  • dick_faust
    Might try contacting John Vig at the IEEE - UFFC and see if he would make the power point presentations available like he has done with his post. I would not
    Message 1 of 7 , Sep 2, 2007
    • 0 Attachment
      Might try contacting John Vig at the IEEE - UFFC and see if he would
      make the power point presentations available like he has done with
      his post. I would not mind getting copies on ppt, but for now I
      think you will have to just copy each frame.

      Dick
      K9IVB
      --- In softrock40@yahoogroups.com, "Claudio Re" <ReClaudio@...> wrote:
      >
      > Thanks a lot Dick !
      > What a nice and huge docs to digest ....!
      > Some documents are in frames and I was not able to download them
      > totally .
      > Any suggestions ?
      > CLaudio I1RFQ
      >
      >
      > --- In softrock40@yahoogroups.com, "dick_faust" <dick_faust@>
      > wrote:
      > >
      > > I was going to write something, but the following references do a
      > > much better job at teaching and answering many of the questions
      > > recently posted.
      > >
      > > Quartz Crystal Resonators and Oscillators for Frequency Control
      > and
      > > Timing Applications - A Tutorial, by John R. Vig [3 formats]
      > > http://www.ieee-uffc.org/freqcontrol/VigBallato/fcdevices.PDF
      > >
      > > http://www.ieee-
      > > uffc.org/freqcontrol/tutorials/vig2/tutorial2_files/frame.htm
      > >
      > > http://www.ieee-uffc.org/freqcontrol/tutorials/vig3/vig3.ppt
      > >
      > > The Fundamental Theory of Low Noise Oscillators with Special
      > > Reference to Some Detailed Designs, by J. Everard
      > > http://www.ieee-uffc.org/freqcontrol/tutorials/FCS%20Tutorials%
      > > 2000/everard.pdf
      > >
      > > Low Noise Oscillator Design and Performance, by Michael M.
      Driscoll
      > > http://www.ieee-
      > > uffc.org/freqcontrol/tutorials/2002_IEEE_Tutorial_files/frame.htm
      > >
      > > Clock Jitter, by R. Temple
      > > http://www.ieee-uffc.org/freqcontrol/tutorials/FCS%20Tutorials%
      > > 2000/Temple_files/frame.htm
      > >
      > > Now my addition is limited to some crystal specifications & notes
      > as
      > > apply to the 20/30M daughter board.
      > >
      > > The crystal should be specified as a fundamental series resonate
      > > device at what ever make tolerance desired. Note: the Butler
      > > oscillator operates on the fundamental frequency which is
      slightly
      > > different than 3rd overtone. I have no idea what drive level is
      > > present, but stay in HC-49 case, if at all possible, as this is
      > the
      > > largest quartz blank.
      > >
      > > The Butler oscillator uses the "tuned" tank circuit to extract
      the
      > > third harmonic and provide the balance of the phase shift and
      gain
      > > required to sustain oscillation. The "tuned" circuit needs to
      > > resonate higher than the third harmonic to meet the operating
      > > conditions and usually is not critical [often why swamped with a
      > > resistor]. The circuit will also work with a fundamental crystal
      > but
      > > at a higher crystal drive current. In both cases the actual
      > > operating frequency will be somewhat higher than the actual
      series
      > > resonant frequency. So use a frequency counter [or radio] to
      > > determine the exact frequency.
      > >
      > > The series resonant frequency of a crystal is always lower than
      > the
      > > parallel resonant frequency. Parallel resonant crystals are
      > > correlated with an external parallel capacitor across the
      crystal,
      > > usually 18pF, 20pF or 32pF. The higher the external cap, the
      > lower
      > > the anti-resonant [parallel resonant] frequency will be.
      > Oscillators
      > > always operate between the series and loaded anti-resonant
      > > frequencies. [Exception: If there is an external inductor, it
      > will
      > > move the series resonant frequency lower]
      > >
      > > It is quite simple to measure the two frequencies of a crystal
      > with
      > > minimum equipment. A stable 50 ohm signal generator or DDS and a
      > rf
      > > meter [a receiver, RF Voltmeter or an rf probe if you have a
      large
      > > enough signal]. Take 2 resistors from 1K to 10K and connect
      > together
      > > in series. Connect one end to the generator and the other to the
      > > meter. Connect one lead of the crystal at the center and the
      > other
      > > to the shields [gnd] of the generator and meter. As you manually
      > > sweep the generator through the series resonant frequency of the
      > > crystal there will be an 80 to 100 db drop in amplitude about 5Hz
      > > wide at the series resonant frequency - so go slow. If you put
      > the
      > > crystal in series with the resistors the same effect will be
      > observed
      > > at a somewhat higher frequency when the elements are parallel
      > > resonant and block the signal. A 20pF cap in parallel with the
      > > crystal will lower the frequency to the 20pF correlation
      > frequency.
      > > The resistors serve to isolate the external strays and give very
      > > reliable readings. The anti-resonant null is much broader than
      > the
      > > series resonant due to the effects of circuit Q.
      > >
      > > A final reference that may be found in Amateur publications is :
      > > DEMPHANO, A device for measuring phase noise, Communications
      > > Quarterly, Spring, 1999, pp. 9-17 by J. Makhinson – cq199904.pdf
      > >
      > > Dick Faust
      > > K9IVB
      > >
      >
    Your message has been successfully submitted and would be delivered to recipients shortly.