General Comments for EMRFD 

  (18 April 09, 22April13, 13Feb15, 25Sept16, 1Dec16, 1Jan17)

  DSP Easy-Kits 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 experiments.  

The experimenter is referred to   W7PUA - DSP-10 Transceiver.

 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/   
I see that this link is still active in February, 2015, but also see that the BF998 is listed as "End of Life."   See A SMT Dual Gate MOSFET Preamplifier for 50 MHz for a dual-gate mosfet application.     The free dual-gate mosfets (click here)  are still available from KE6F in August, 2016.

Discontinued Transistors:    Within 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      

CD Problem:     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.   (22April 2013)


Please let us know about the errors that you discover.  Just drop any of us a note at w7zoi@arrl.net, kk7b@arrl.net, or w7pua@arrl.net.   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!