Errata, Chapter 7, EMRFD


p7.7, Fig. 7.13.  The 78L05 regulator has the input and outputs transposed.  (30Oct03)

    p7.8 and 7.9.   Move the "7.4" section heading from p7.8 to p7.9 to become "7.4  Attenuators"   Attenuators is a major subject while RF power measurement with an oscilloscope is part of the previous section.    (10Dec03)

New in 2016  p7.9, Fig 7.19 caption:   The second sentence should read  "....pick R in Ohms and A in dB and ....."      (29Sept2016)     

  (The 3rd printing does NOT include the 455 kHz output details shown below.) p7.15, Fig 7.27.    I got a question and comment the other day from a reader regarding this general purpose test oscillator.   I ended up taking the cover off of the box to check the circuitry against the schematic and noted both an error and some modifications that have been done since the original design.   The error was that there is a 330 Ohm resistor in the diagram that is not needed in the design.  In reality, the 330 Ohm resistor in the bias network for the output stage will serve as the 2nd R is the 3 dB pad.    This is not going to be a major performance change.    The changes are minor, but may be of interest to those of you are building a similar generator.   Mainly, the output power is increased with higher gain in the output stage.   This is realized by adding another emitter resistance that decreases the overall degeneration.    The circuit is shown here:

At one point I got some 455 kHz ceramic resonators and wanted to test them.   I did this by sampling the output of the low frequency generator, converting it to a logic compatible signal, and then dividing the signal by 16.    The output is buffered and low pass filtered and applied to an output connector.   Another port provides a port for counting.    This generator has proved to be extremely useful for experiments with 455 kHz resonators and monolithic filters.    The circuit is shown below, even though this goes beyond being an "errata."
  p7.19, Fig 7.32.   The toroid core in the collector of the crystal oscillator stage should be a T37-6 rather than FT-37-6.   That is, it is a powder iron tuned circuit rather than one with a ferrite.   (15 Oct 04)

p7.19, Fig 7.32.   Errors were discovered in the schematic.  The differential amplifier is biased with a 330 Ohm resistor instead of 1K. Further, the differential amplifier runs from the 15 volt supply rather than from the 9 V on-board regulated supply.   An updated schematic is presented with the changes shown in red.    The red changes include the toroid type error found in 2004.   Also included in the drawing are measured signal levels obtained with a Tektronix 465M oscilloscope and 10X probe. The module was terminated with 50 Ohms during measurements.  (21 Oct 05)     The third printing still shows a 100 Ohm resistor between the 100 uF on the 9 volt Zener and the collector of the left Q in the differential pair.    Zap that resistor.   (17April 09)

  p7.21, 1st col., 2.7 inches down from top.  Replace "some components may required..." with "some components may require..."  (3Dec03)

  p 7.23, Fig. 7.42.  The lower signal generator, V2, should include a ground symbol.  (3June03)

  p7.29,  Fig. 7.54.   There is some information missing from the figure.  The complete figure is shown below:


  p7.30, col 1. 0.9 inches up from text bottom:    Replace "question ask" with "question asked"     (8Feb03)    

  p7.39, just above Eq. 7.7      Change "Noise figure is related Y factor by" with "Noise figure is related to Y factor by"  (29Jan06)    

  p7.42, photo caption.   Replace "the lid is then place " with "the lid is then placed "     (3Dec03)

  P7.43, reference 20.    The reference shown for Spectrogram is no longer valid.   However, users can find a download version of Spectrogram at   Another interesting audio spectrum analysis program is Audiotester.    This program can be found at .    There is no charge for Spectrogram.    An evaluation version of Audiotester is available on the site shown and the registered version is available for Euro 35.   (16Aug06)