Digital QRP Homebrewing     

~~ INDEX ~~

QRP BreadBoard

Column #1: 

Project Description,
block diagram & layout


Column #2: 

HC908 Daughtercard
& the Scaling Voltmeter 
software application


Column #3: 

Adding frequency synthesis 
with a DDS chip


Column #4: 

SWR bridge & buffer amp for Antenna Analyzer application


Column #5: 

Baseboard & Enclosure


Column #6: 

Frequently Asked Questions


Column #7: 

"Hello DDS" - Making your First Program



Spotlight Projects


  #1:   PSK31 Audio Beacon


  #2:  The G4GXO Dual-PIC DDS VFO


#3:  "Badger" SmartBadge


#4:  PIC-based APRS Weather Station - Part 1


#5:  PIC-based APRS Weather Station - Part 2


#6:  PIC-based APRS Weather Station - Part 3


#7:  PIC-based APRS Weather Station - Part 4


Related Info


Rainbow Antenna Analyzer -II


DQH - Background & Goals


Return to 
home page


May 2003:


Now that homebrewers have their HC908 Daughtercards in hand, the topic for this installment deals with creating special, custom programs with the easy-to-use Template program supplied with the project. We’ll show how one can easily create a ‘Hello DDS’ program to meet specific signal source needs on the bench. 


Speaking of the HC908 Daughtercard, we have a tremendously useful Resource Page set up for users of the daughtercard containing online documentation, application notes, special guidance and instruction, tools and lots of software.  Some HC908 Daughtercard owners are going gangbusters in creating applications with this project and they are sharing back with us all.  Further, we've highlighted a Motorola Application note that descibes how to make a very low-cost programmer for the 68HC908AB32 microcontroller ... so if you want to go one step beyond the built-in capabilities of loading custom software, you now have the super inexpensive way to even modify the HCmon debug monitor to your liking! (Thanks to Tom W8KOX and Nancy NJ8B Feeny for pushing this envelope.)


The second theme of this website concerns the fourth installment of the PIC WX project – the PIC-based APRS Weather Station. Designer NK0E adds a wind speed indicator to his growing project using some clever techniques and a homebrew anemometer.  Dave is getting lots closer to completing this project and we'll soon see how he couples the hardware/software end of the weather station into the radio portion of the APRS system.


We're now working on a real interesting add-on project to the Digital Breadboard ... the DSP Daughtercard! As planned all along, this daughtercard will allow the Digital Breadboard to perform as a Portable PSK unit by providing PSK31 digital modem capabilities.  The cool part about this is that is that we've begun collaboration with Lyle Johnson, KK7P to use his DSPx module in the Digibal Breadboard project. You can see details concerning the KK7P DSPx module at By working with KK7P and his already-available module, we'll be able to bring the "Portable PSK"  Digital Breadboard to kit availability lots sooner than originally forecasted! You can even order your DSPx module right now from KK7P, or you can wait for the introduction of the Digital Breadboard later this summer.  The Digital Breadboard Kit will include an option to purchase the KK7P DSPx module at a significant discount.


Yet another of the fascinating "digital" topics that we're working on for our column and website concerns Software Defined Radios.  Some of you may have been following the article series in QEX magazine, authored by Gerald Youngblood, AC5OG, wherein he developed a pc board set that functions as a high-performance, multiband QRP transceiver controlled by a standard PC.  (See The radio relies on the DSP processing provided in the PC's sound card and the computer displays a dazzling operating console to the monitor allowing the user to see and control every aspect of the radio's operation. I've been experimenting with this SDR-1000 transceiver and will bring my initial findings and overview to this Digital QRP Homebrewing venue next time.  


Indeed there is lots happening!  Please have fun with all this material and be sure to feedback how your HC908 Daughtercard application is coming along.  Also, Dave Ek NK0E would be real interested in hearing of your progress with his PIC-WX Weather Station project..


73, George N2APB





"Plug in those soldering irons and bring up the source code editor on the computers because we’re about to take you on an “educational and practical journey” of hardware and software homebrewing!"  

That's how our first column started in the Fall 2001 issue of QRP Quarterly.  We have many interesting projects in store for our readers in each printed issue of QQ, and equally important, right here online in this companion website. 

As our name suggests, we're focusing on the general topic of digital QRP homebrewing ... which covers applications of "digital devices" that can be applied to our homebrewing QRP ham radio hobby. These digital devices can include microcontrollers, DSPs, PCs, PDAs and even specific digital chips and modules from various manufactureres. 

We'll be exploring and experimenting with both hardware and software aspects of homebrewing. This approach will take many readers into new territories.  The traditional RF homebrewers among us will get a chance to try building simple PIC microcontrollers projects that will be useful in the radio shack. We'll actually be working with a full range of microcontroller types and vendors in the growing number of projects we'll have online here.  

At the same time, traditional software jocks in our ranks will get a chance to program and modify some useful programs for these same QRP projects. We'll guide you through various algorithms and programming techniques using some commonly-available tools and applications. We'll be programming in assembly language, C and BASIC using inexpensive (and even free) software tools that we're arranging for your use.

2 Parts to this Website
As you'll recall from our printed column in the pages of QQ, we've structured this companion website into two parts:

The Digital QRP BreadBoard is a tremendously exciting and novel QRP project we started in the Fall 2001 issue of the column. We're developing a general-purpose QRP accessory that can be used on your operating bench and in your radio shack in a variety of different ways. Approximately 6" x 9" x 1.5" in size, this project contains a number of peripherals that QRPers will find useful in applications around the shack – an LCD, shaft encoder, DDS chip, audio amplifier, RS-232C serial port, general purpose I/O buffers, and a daughterboard expansion port all provide convenient design flexibility. You'll be able to download and reprogram (at no cost!) the software in your Digital Breadboard, allowing it to serve as a memory keyer, an audio filter, a keyboard-driven data terminal, a controller for your HF rig, a frequency counter, and more.  Sharp readers will discover that we'll even be able to make an inexpensive portable PSK31 controller with the DSP daughterboard to be introduced in a near-future installment of the Digital BreadBoard project.  There is much functionality, education and fun planned with this evolving BreadBoard project. A kit of parts is available for homebrewing readers to easily build right along with us in each issue.  This website will be kept current on an even more frequent basis, allowing additional and timely hardware and software to be available in between issues. 

The Featured Projects section spotlights a current and/or popular QRP club kit.  It will be an inexpensive kit that can still purchased from the sponsoring QRP club, or otherwise obtained. Using that kit as the basis for our experimentation, we'll break the project down, with the author's permission and oftentimes his involvement, into the basic hardware and software blocks comprising the design. Then we'll reconfigure the software and perhaps add some simple hardware interfacing components in order to create a new project from that original kit. Using this approach, you'll be able to get a readily available microcontroller-based project pc board and components to start you off with your new project each time. Heck, long-time QRPers probably already have these kits someplace on the bench and can start playing long immediately when each new issue of our QQ column hits the streets.  Everybody wins - the club gets a sale of the kit, the kit designer gets additional fame, and you get a proven base project with which you can start experimenting right away!  The Index column on the left side of this page is a running list of links to the projects we've been presenting in this section.


Thanks for your interest and support for this fun new digital aspect of our QRP homebrewing hobby.  We have tons of exciting projects and experimenting already in the works, for the pages of our column in QRP Quarterly and for this companion Digital QRP Homebrewing website. 

Let us know how you feel about our plans, projects and progress ... we'd love to hear from you!

--George Heron, N2APB


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Page last updated: January 22, 2003