EMRFD Index, CD, and
(17 April 09)
Add both "IL" and "insertion loss" to the
index with "in filters...p3.1, in receiver
roofing filters...p6.50" (10Aug03)
p507, index. The correct name of VE7QK is Derry
(not Jerry) Spittle. (24Feb03)
Book CD: We have found a
minor problem with the CD. When the
CD is inserted, a file "articles.pdf" appears on a
directory listing of the CD drive. Double clicking
this file causes it to run under the Adobe reader. Then,
any of the articles included on the CD can be viewed
by clicking on the listing in the "bookmarks" along the
left screen margin. But the file for W7EL's "Optimized
QRP Transceiver" sometimes produces an error message.
It can be viewed if it is the first file called
after the "articles.pdf" file is run. (20Mar03)
[I have not yet checked this one, and it may be fixed
on the second printing. w7zoi 30Sept03]
Computer Design Programs
DTC and TTC (from CD): Both of these programs
include an estimation of the insertion loss for the bandpass
filters designed by the programs. This is an estimation
based upon the equation given on p 3.10 of the book. If
a better loss number is needed, the filters should be stored
with the file|save_as command, and then analyzed with the general
purpose ladder analysis program, GPLA. GPLA is not
an approximation, but an exact analysis based on the ladder method,
presented in detail in Intro. to RF Design, p51. See also
RF Design Magazine, Sept/Oct., 1983. Although GPLA is exact,
it is limited by the element models used. That is, capacitors have
no series inductance and no loss; inductors have no parasitic capacitance.
The analysis is limited to simple ladders with no mutual elements
other than those between adjacent elements.
The new programs in LADPAC08 no longer contain the insertion loss estimate.
Instead, other parameters are presented that may be of use to the
I recently realized that many folks have been trying to fight their
way through the programs, after they realized that they were even there,
without even knowing that a manual existed. The manual is on
the book CD. Insert the CD and look at the CD with Windows Explorer.
Go into the directory Software
and then to the sub directory LADPAC2002.
In this you will fine a long text file, LADPAC2002.txt, which is the manual.
Double click it to open it. You may wish to copy it to the directory
containing the design programs. (31Oct06)
Articles on the CD:
It is not our intention in general to offer any updates or errata
for any of the magazine articles on the book CD except in some special
situations. A special circumstance that we might consider
is if the subject is of general fundamental interest.
(This item was "fixed" by including the program "Padcap08.exe"
with the other software.) Article #30. Appendix to "A Progressive
Communications Receiver," QST, November, 1981. This presents
equations to calculate the fixed capacitors needed when a variable capacitor
is padded to behave as if it was a smaller value. A typical application
might be the use of a 365 pF variable to tune over a small frequency range
where a variable of just a few pF is really needed. An error
is present in Eq. 3. of the appendix, p21. The first term on the
right hand side of the equation should have a subscript of U rather
than V. The complete equation set is given here:
Fundament units (Hz, Henry, Farad) are used.