(18 April 09, 22April13, 13Feb15, 25Sept16,
Comments for EMRFD
from Analog Devices have been the basis for Digital Signal
Processing experiments reported in EMRFD and for the earlier
DSP-10 "Software Defined Radio" described by Bob Larkin,
W7PUA. Unfortunately, the Easy-Kits have been
cancelled (or priced to discourage private experimenting) by
Analog Devices. For a while we had a solution in the form
of a board designed by Lyle, KK7P, but that solution is no
longer available. Many thanks to Lyle (and
TAPR) for his efforts to help experimenters with DSP
experimenter is referred to W7PUA - DSP-10
Dual Gate MOSFETs:
Chapter 6 includes considerable information on IF
and RF amplifiers for receiver applications. Some of the
circuits use dual gate MOSFETs, a component that was popular
about 20 years ago, but not in common use these days.
The dual gate FETs are still available and are highly
recommended for AGC amplifiers, or for low noise applications.
I got a very interesting note recently from Mark, WU0L.
Mark had purchased some BF998
surface mounted dual gate MOSFETs from Bob, KE6F, Via EBay.
I also got some of these parts from Bob. Mark
beat me to the punch and has built the AGC IF amplifier that
was used in the Progressive Communications Receiver.
This circuit, from QST, November, 1981, is included on the
EMRFD CD. Mark reports "good gain and no
stability problems" with his version of the circuit. He
did his own circuit board. Many thanks for the info
Mark, and many thanks to Bob for supplying the parts.
A data sheet for the
BF998 is available from the Philips web site at: http://www.semiconductors.philips.com/
that this link is still active in February, 2015,
but also see that the BF998 is listed as "End of
A SMT Dual Gate MOSFET Preamplifier
for 50 MHz for a dual-gate mosfet
The free dual-gate mosfets (click here) are
still available from KE6F in August, 2016.
a few days of EMRFD publication in 2003, we saw the
discontinuation of a transistor used in a project. This
one was in Chapter 1 where we used a 2N5321 as a power amplifier
in a 2 watt transmitter. This is going to happen,
but we hope that the information is fundamental enough that it
will transcend these details. Other transistors have
come and gone and now seem to be history. But a good
bipolar RF power part for HF is the BD139. It's even cheap
and seems to be available from several sources. 25Sept16.
On Jan 25, 2004 we discovered a problem
with compact discs distributed with the 2nd printing of
the book. It appears that text is missing from all of
the QST/QEX/HR/Microwave-Update articles in the
collection, only to be replaced by a page from another
article. The CDs with
the first printing are generally OK. The ARRL folks have fixed this
problem and the books being shipped are good.
This problem was only present with the 2nd
printing of the book. The CD with the 2nd
printing has a silver cover.
The replacement CDs will
be blue. If you have a defective CD,
you should contact ARRL and ask for a replacement.
The files with the 3rd
printing are fine. (17Apr09)
The CD distributed
with the third printing (a.k.a., "revised
first edition") has a silver color.
let us know about the errors that you discover. Just drop
any of us a note at firstname.lastname@example.org, email@example.com, or
firstname.lastname@example.org. Let us know which printing
you are reading. Page
numbers and position on the page would also be useful when you
write. We really do
seek and appreciate your feedback! Many thanks!