I started building electronic kits about this time last year. (My grandmother got me a soldering iron for Christmas.) At this point I’ve built several kits, but I’ve only gotten around to posting about a couple of them. This kit, the NorCal Dummy Load was my third project, the first being the MintyBoost, and the second being a AVR microcontroller programmer that I haven’t had a chance to post about yet. More on that one later. I built this kit back in February of 2009. You can see all the photos here.
Dummy load in vise, on desktop.
So, what the heck is a dummy load? When you’re testing a transmitter, you can’t just transmit without anything connected to the output. You could fry your final amplifier. So you need a dummy load that presents the correct impedance, 50 ohms in most cases. As it just so happens, I’m getting ready to build a transceiver, and will need a dummy load for testing. Also, this particular dummy load involves several surface mount (SMT) parts, and I wanted a little practice with those before beginning my next project, the Softrock Lite II 30m software-defined receiver.
This kit was designed and sold by NorCal QRP, a low-power (QRP) ham radio club based in Northern California. They have put together several kits over the years. They actually retired this kit a couple of years ago, but I inquired on the qrp-l list and someone had one they weren’t planning on building.
Some hams are intimidated by surface mount (SMT) components, and rightly so; they’re pretty small. Have a look below. The small black thing to the right of the penny is a 2.2 kOhm SMT resistor. SMT components come in different sizes. This size is referred to as 1206, which means it’s 0.126″ × 0.063″. It’s one of the larger sizes of SMT components.
As it turns out, soldering SMT components isn’t too bad. I used a small tip on my soldering iron and small solder (0.015″ diameter) and had no problems. There were no SMT integrated circuits on this project, but there would be on my next project.
Tonight I started on another SMT project, but using solder paste, a griddle, and an embossing gun instead of solder and a soldering iron. More on that later.