HOMEBREWER #6

Content for Issue #6



Cover of HOMEBREWER issue #6
(Click photo for larger view)

(Having trouble seeing the entire issue?  See the note at the bottom of this page for possible cause.)

Welcome!

    The contributing authors have once again overwhelmed us and allowed us to produce a terrific issue of Homebrewer Magazine. Contained in more than 500 pages of full color, high resolution graphics, we have a mixture of easy and complex, quick and extended, antennas and radios, digital and analog … something for everyone to build, and educational for everyone even if you don’t build up a given project.

The highlight of the issue, and the cause of a great deal of excitement in the QRP community during August-September, is something called the SoftRock-40 Receiver. This little 1”x2” board from designers Tony Parks KB9YIG and Bill Tracey KD5TFD plugs into the USB port of your computer and works together with a powerful software application from FlexRadio called “PowerSDR” to provide a 40-meter receiver with absolutely stunning performance. The exciting  quadrature sampling detector enables the software on the PC to pull out signals as low as 40 dB, thus rivaling some higher-end commercial receiver performance.

Bruce Beford, N1RX provided a nice service to many on QRP-L by experimenting with a different crystal to move the SoftRock to 30 meters. He obtained some crystals in quantity and supplied them at cost to SoftRock owners wishing to modify their kit … and Bruce wrote up a nice article for Homebrewer explaining how he went about designing the mods.

And speaking of quadrature sampling receivers, we had a surprising contribution from a pair of wonderful designers from Finland, Juha Niinikoski OH2NLT and Matti Hohtola OH7SV. These guys designed and built an award-winning, 0-8 MHz DDS-based QSD receiver called the JUMA-RX1 that has nice specifications – and I’m currently in the process of building this one up myself!

Software Defined Radio (SDR) radios are becoming quite popular these days, much due to the excitement and interest generated by FlexRadio Systems’ SDR-1000 transceiver. We had a review of this radio way back in in Homebrewer issue #1, but QST recently published a wonderful review of this same radio and covered the many new features that have been added since we saw it here. So in joining with the surge in popularity of SDR, we re-published our original SDR review written by designer Gerald Youngblood K5SDR. We also have included the well-done QST review. And lastly we have added the technical overview of SDR technology that software radio guru Bob McGwier N4HY did for us in the Atlanticon 2004 Forum. This is a one cool collection of SDR reference material!

By the time this issue gets into your hands, the AmQRP likely will have announced details and availability of the DDS-60 Daughtercard. The article in this issue describes how we extended the frequency range of the original DDS Daughtercard by going to an AD9851 DDS chip and including the DDS Amp project right on the main DDS card itself. We went to using the AD8008 op amp to provide a nice, flat signal level right out to 60 MHz, and we retained the use of the SMT trimpot to allow output level adjustment. Then as a builder option, we provide DS-1804 digipot to allow the external controller software to also change the output level.  Pretty neat!

Again along the line of DDS signal generation … two DDS chips have got to be better than one, right?  Lyle Johnson, KK7P thinks so, and he provided an article describing his DDS2 dual chip design that forms a building block for a software defined radio clock generation circuit. By operating two RF clocks of the same frequency but having 90-degree phase difference, one has the start of some great signals to drive QSD and QSE circuits on an SDR radio.

We are also fortunate to be able to include KK7P’s Atlanticon presentation of Digital Building blocks for Analog Radios. He received rave reviews from the Atlanticon audience this past spring, and now you’ll have a chance to see into the mind of one of the brightest QRPers in our midst.

Noted designer of the famous HAMCALC program, George ‘Murph’ Murphy VE3ERP worked with W2AHW to produce a design of a miniature magnetic loop called the Octaloop. Imagine having an Small Transmitting Loop (STL) antenna for 80m that is only 52” in diameter! Murph and Harold provide some clear and easy plans on how this can be effectively accomplished.

The PIC-based weather station article series from Dave Ek, NK0E has spanned two magazines and 5 years’ time. We’ve provided here in this issue of Homebrewer the full series of PIC-WX articles and software so you can easily build up the project without referencing many back issues.

We are so fortunate to have the homebrewing expertise and talent of Paul Harden, NA5N with us as a regular contributor to Homebrewer Magazine! Paul’s “Handyman Series” this time overviews the homebrewing techniques of Manhattan construction and you’ll be absolutely thrilled in reading though his installment.  Outstanding stuff!

Some years ago,  we introduced Craig Johnson’s PIC-EL project board along with the start of the Elmer 160 PIC-training course for hams. The “Pickle” board was very popular as it had lots of useful peripherals that we QRPers and homebrewers could use in actual applications on the bench. Not the least of them is the DDS Daughtercard, and because of it many people are now using the PIC-EL at heart of a precise RF signal generator sitting on their benches. Since the AmQRP recently spawned another run of the PIC-EL as a partial kit (board plus several hard-to-get components), and KangaUS stepped up to make up bags o’ parts for the remaining components, Craig and I felt it more than appropriate to collect the PIC-EL documentation, add a little more to it and publish it all here together for Homebrewer readers.  Enjoy!

Dave Ottenberg, WA2DJN is a regular contributor to Homebrewer Magazine and he prides himself in finding simple ways to produce useful instruments for the workbench. This time Dave found a nice test oscillator circuit and he packaged it in a plastic tube for use as a signal injector.

Another fairly-regular contributor to our Homebrewer journal is Phil DeCaire, WB7AEI.  This time Phil explores the ever-present world of Low Pass Filters and provides us with some useful tools, simple equations and practical examples in their use.

Steve Holton, N1NB spent a lot of time with KK7P and me in designing the AF-908 DSP audio filter. In doing so, he became very familiar with the Micro908 hardware and software capabilities and he applied it in solving a challenge we made at this past Atlanticon: stabilize the Crystalizer! Steve designed a simple interface for the Micro908 to control the Crystalizer and wrote a nice program using a thermister in a control loop to keep the Crystalizer frequency right on the mark.  By the way, he won first prize at Atlanticon for his effort here!

Victor Bresedin, UA9LAQ contributed two articles to Homebrewer this time, and in his own unique style provides us with some of his wonderfully-stated designer wisdom.  His overview of his 20-meter receiver, and a walk-through of an experimental 2-meter antenna provide a delightful and informative read.

Joe Everhart, N2CX has been doing the design series called Power Meter Cookbook for a number of issues.  He is now getting to the point in this current installment of getting us past the “analytics” stage and on to practical incarnation of his designs. You can wire up the circuits he provides this time and make some great headway on better understanding the theory presented thus far.

We are very fortunate to have received permission from Murph VE3ERP to include his ever-popular and ever-improving HAMCALC program set on the Homebrewer CD-ROM.  You can find his latest program (#78) in the Software section of this CD.  Assistant editor Nancy Feeny NJ8M also felt that it would be useful in each issue to have a walk-through of one of HAMCALC’s features in a real-life example, and she’s provided a nice tutorial on designing a power supply with the appropriate programs in HAMCALC.

There are some good projects that just never lose their value over time, and it’s curious how some designer/authors always tend to be the source of those projects. Jim Kortge, K8IQY designed the Precision VXO project some years ago and presented it at Atlanticon to a very eager audio.  Then in the following months he provided the design for a mating Crystal Measurement fixture to give us homebrewers some real useful capabilities on the bench.  We present both of these instruments again in the Homebrewer pages … if you missed building them the first time, here’s a chance to reprieve yourself!

In the last issue, Al Gerbens, K7SBK introduced his Excel macro “program” called AA908 Plot Gen that took the raw data file produced by a scan of the Micro908 Antenna Analyst and displays a wonderful plot of the SWR, resistance and reactance. Never one to be satisfied with something that works (like all of us, I think!), Al made a raft of feature additions that further increase the usefulness of this tool.

Joe Everhart’s N2CX Test Topics and More (TTAM) column this time around shows some basic electronics that are relevant for more than just test equipment. The “Designed for Test” section shows how to use a 75-ohm attenuator with other equipment and cables designed for a 50-ohm impedance using a so-called minimum loss pad. Joe’s “Coming to Terms” section deals with series and parallel equivalent circuits, a topic that comes up now and again, particularly in conjunction with impedance matching. “Stimulus and Response” talks about power attenuators – how to design them and how to size the components that make them up.

Recurring columns are the staple of most magazines and Homebrewer readers are able to be regularly exposed to the experience, wit and storytelling grace of Richard Fisher KI6SN and Arland K7SZ. Through the KI6SN “QRP Operating” column we get a view into some of the Field Day experiences that some guys had  this past summer. Then in two K7SZ “Tuning Up” columns this time we learn how Digital Dickey was converted from an analog world, and how that same analog world (a la that troublesome Argonaut) nearly did him in.

Ken Newman, N2CQ once again gives us a 3-month forecast of QRP Contesting events, including links to all the associated rules web pages. As an added treat, Ken supplied us with the full 5-year set of results from the Homebrewer Sprint event that he runs during the spring and fall of each year. What a great compilation of contesting results!

THREE SPECIAL FEATURES!

We are very proud to present a first-of-its-kind (to the best of our knowledge) in our QRP publishing world by producing, editing and publishing an instructional video within the “pages” of Homebrewer Magazine. Joe Everhart N2CX and I (N2APB) collaborated to present a 45-minute video overviewing the technical aspects of the Micro908 design. This WMV file is able to be viewed in the standard Windows Media Player (or equivalent) on most computer systems, and we think you’ll enjoy actually seeing the designers describing their project

There is another great bonus feature in Homebrewer this time that you can’t find anywhere else. We had an opportunity to interview the designers of the SoftRock-40 (Tony and Bill) and we provided this hour-long audio file on the Homebrewer CD for your listening pleasure. So not only can you read about this popular little rig, but you can hear from the designers in their own words about the project, the process they followed in developing it, and some of the future directions they’ll next be taking the SoftRock.  Be sure to listen in on this interview!

We are very thankful to Chuck Adams, K7QO for allowing us to include his comprehensive Morse Code Training Course in this issue of Homebrewer Magazine. Chuck is actively involved in training ham clubs in the proper learning and use of Morse code, and he is quite an accomplished in this communications mode. The K7QO Code Course consists of 149 MP3 files located on this CD, plus some expert guidance provided by Chuck and several related reference articles.

SOFTWARE on CD

There is a ton of software programs, source code, and other files relating to the articles and projects presented in this issue of Homebrewer. The best way to see and use these files is to use your file browser to navigate to the CD drive, and then into the Software folder. You will either see a folder with the name of the individual software program, or a zip file that contains a compressed file of all the related files for that named topic. These files will best operate when copied to your computer’s hard drive. (Also, you should not attempt to run a program while it is still contained in the compressed zip file container – you will get unexpected results.)

Notable programs and files included in the Software folder this time include: HAMCALC 78, PIC-EL design and software files, GCGC (Great Circle), WA0SVL Conversion utilities, AA-908 Plot Gen, source code from all the PIC-WX articles, Serial DDS source code, Link908 source files, SoftRock-40 and PowerSDR source and installation files, software files for the JUMA-RX1 Receiver controller, TC908 Temperature Controller software, … and more. This folder is a software homebrewer’s treasure trove!

Also, the Why QRP? presentation is included for your use at local club meetings. Lastly, as before, we have included the detailed Kits folders including all manuals, schematics, software, pcb layouts, etc., for current and popular QRP kits that have been produced over the years. This is a great reference bank of technical homebrewing information!

 

72, George N2APB  n2apb@amqrp.org

 

Problems Opening This Issue?
Several people have commented that they "only see the first 7 pages of the Homebrewer Magazine".  The whole magazine is really there, trust us! The first, automatically-opened file is a 7-page PDF file called intro.pdf that serves as an introduction to all the contents of the CD and provides launch point hot links for the main PDF file of the magazine (e.g., when you click the photo of the cover) and other contents. If the hot links are not being interpretted by your operating system or Adobe Reader, try using your file browser (Windows Explorer, or equivalent) to view the file contents of the CD drive when the disc is inserted. You will see the main PDF file for the magazine called HB6.pdf and you can manually click on it to open and view all 509 pages. Similarly, you can navigate around the other CD files to access the rest of the wealth of information on the CD. Good luck and let us know if you have any problems reading the magazine.

 

Back to the HOMEBREWER Page

 

Page last updated:  October 22, 2005