Errata, Chapter 7, EMRFD
p7.7, Fig. 7.13.
The 78L05 regulator has the input and outputs
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.
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
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)
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)
1st col., 2.7 inches down from top. Replace "some
components may required..." with "some components may
7.23, Fig. 7.42. The
lower signal generator, V2, should include a ground symbol.
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"
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 www.n0ss.net. Another
interesting audio spectrum analysis program is Audiotester.
This program can be found at www.audiotester.de
. 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)