Errata, Chapter 7, EMRFD
(17 April 09)
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)
(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."
(18dec06)
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:
(5May03)
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 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)