When I was a child, my grandfather got me interested in electronics. He was a part time television repairman – back in the days when televisions were able to be fixed on the basement workbench. He bought me a Radio Shack 150 in One Electronic Experimenters Kit, and I was hooked. I used to cherish the first Thursday of the month – which was rubbish day. Old television sets were placed at the curb, and I would take my wagon and my father’s tools, and I would rip the chassis out of the TV and take it home. A few hours later I had a nice set of parts. A trip to the library earned me a book on building electronic circuits, and I was off to build something. My favorite projects were radio receivers and transmitters. My father suggested I investigate getting into ham radio. There were no hams in our family, but my grandfather had a friend who became my mentor. The rest, shall we say, is history.
Now to the present. It was building things that got me into ham radio, and I still love building things today. The pandemic has given me a chance to spend more time in the basement workshop. I built an Arduino-based APRS tracker that is in my car. It has a homebrew synthesized transmitter and TNC. You can find the plans here (it is not my design): https://hamprojects.wordpress.com/2015/06/29/vhf-beacon-and-aprs-tracker-english-version/ . To give it a bit more power, I build a 20 watt FM amplifier – plans are here: https://www.qsl.net/sv1bsx/mhw612/mhw612.html .
In another project, I took the same 2 meter transmitter circuit and wired an Arduino Nano to it. The transmitter’s chip is programmed to send a continuous tone at whatever frequency you select, and the Arduino Nano takes input from a connected PC and translates it to Morse code that is sent over the air. That is the device that was used for our code practice sessions earlier this year.
I then got into foxhunting. Inspired by Dave Tipping NZ1J, who hides with three transmitters at different power levels on different frequencies, I decided to build three 2 meter fox boxes. The first uses the same circuit I described above, but the onboard ATMEGA chip is programmed to beep periodically and send my call letters every 30 seconds in Morse code. This unit is in my 0.5W fox box and uses very little battery power. I built one of Dave’s circuits for the 1 mW version. You can find the plans here: http://www.w1nrg.com/website/1mW_2Meters.JPG. Finally, I built WB2HOL’s 40 mW fox box, which you can find here: http://www.w1nrg.com/website/Radio%20Direction_Finder%20RDF%20Projects%20Joe%20WB2HOL.pdf . Building all of these projects taught me a fair bit about different techniques to generate RF, and with NZ1J’s help, I also learned how to design and order custom PC boards. That was a big help!
Since I really like computer programming, I shifted my attention to an Arduino accessory for my shack. I really like my IC-7610, but one frustrating thing is that access to some controls is buried within submenus that are accessed on the touchscreen. One that I use frequently is the RF power control, as my linear takes a maximum of 50 watts. If I want to run barefoot, then I find myself adjusting the power often. I wanted offboard control without having to use a PC (as my screen is usually cluttered with a lot of other programs). Therefore, I designed and built an offboard dial box that has six buttons and five knobs. These controls can be programmed to cover any function encoded by CAT codes on the Icom CIV line. The unit incorporates a TFT display that shows the parameters controlled by the dial box and their levels. Thanks to Tim, KC1TWR, who loaned me his Kenwood HF radio, I ported the code to cover Kenwood and Yaesu radios as well (they use identical CAT commands, which are different from Icom’s). This project has been accepted for publication in QEX. I hope the article will appear later this year.
What is the point of all this? Both in my work as a scientist and in my hobby, I like constructing things and learning about how they work. One of the great things about our hobby is that you can experiment and put the fruits of your work on the air. Unlike in the UK, here in the US you do not need a special amateur radio license to experiment and use your homebrew equipment. If you have any questions or if you would like any of the plans for the projects I have built, drop me a note at KE1IUmark@gmail.com. I am willing to freely share my schematics and my code. I am also happy to discuss other projects that I have built over the years.