Errata for Chapter 3 of EMRFD
(31 July 09)

p3.19, Fig 3.35.  This is not a report of an error, but rather, a revision to an existing method.    Jack Smith, K8ZOA, pointed out a very interesting omission that we made in the formula we use to calculate motional inductance from the frequency shift in the G3UUR type crystal oscillator.   The capacitance we had used was just the series C that is inserted by the switch, including the capacitance of the open switch.   This value should also include the crystal parallel capacitance, or holder C as it is sometimes described.   The figure below summarizes this:
 
The parameter C0 is the parallel capacitance of the crystal.    This is measured at low frequency with a device such as the AADE LC Meter.  This change is not a error that needed fixing.   However, I would recommend that anyone reading this mark it in their copy and use the refined equation.   It is typically a 5 to 10% kind of refinement.   (22may06)  (15Nov07)  

p3.23 and 3.24.  On these pages we describe the behavior of a "linear phase" crystal filter.   The use of the term linear phase is just an approximation here.  This filter was designed using the "linear phase with equal ripple error" k and q tables from Zverev.  These tables are an approximation, as is often done in network synthesis.  (Indeed, the Chebyshev filter is an approximation with ripples emulating a perfect brick wall filter.)  Also, the base filter is a low pass design.  Here, it undergoes a lowpass to narrow bandpass transformation when a practical filter is designed.   The approximations as well as the transformations lead to departure from the ideal of a perfectly flat group delay.   (This is more of a comment than an actual errata item.)  (29Apr03)


p3.26,  add text just below Eq 3.23.   "This is identical to Eq 3.18."  (10Apr04)

  p3.28.  Left column, 1.6 inches down from text top.  Says "all all".   Should read at all frequencies.  (5Mar03, 10Apr09)  

p3.30.  Left column, 1.3 inches up from text bottom.  "It's" should be "its".  (31July09)  

p3.36, left column, 0.7 inches up from text bottom:  replace "while Hybrid refers" to "while hybrid refers"   (9Dec03)