I ran across some code for turning a raspberry pi into a wspr transmitter with nothing but the GPIO pins (and a filter). Here is the code repository. I loaded up a raspberry pi with raspbian lite and compiled the WsprryPi code. From there, it was just a matter of adding a filter between the GPIO pins and the antenna. I fired up the software and let it transmit for about a half hour or so and here is the result.

Now that I have my homebrew paddles, I’ve started working on a keyer. This seems to be the most polished/feature rich open source keyer that I have been able to find. I started out with a pack of knockoff arduino pro minis that I picked up off Amazon. Out of three that I tried, one was DOA and the other two were missing bootloaders. I burned the bootloaders to the two that were working and started tinkering.

Now that I’ve got several morse code transmitters, I need a better way to key them than grounding a wire or toggling a switch. Looking online, I can see that like everything else ham radio, morse keys are ridiculously expensive for what they are, so I guess its good that I like building my own gear. I started with a small scrap piece of red oak and some brass brackets and hardware.

Last night I finished up a version of the Universal QRP Transmitter from the book Solid State Design for the Radio Amateur. I changed a few bits here and there, but it is mostly the same circuit from the book. Here is the schematic that I ended up with. The book used T50-2 toroids for the transformer and filter coil, bit I ended up using T37-2 toroids and adjusted the number of windings using the wonderful toroids.

I first got into radio when I found out about the RTL-SDR dongle. I am an IT guy by trade and have always been interested in programming and hacking, so when I saw that I can get a $10 dongle, hook it up to my computer and pick up rf signals from garage door openers, wireless remotes, and even airplanes, I started reading all I could. The first thing I did with the dongle was set it to receive ADS-B signals from planes.

I recently came into possession of a pile of old uninterruptible power supplies that were headed to the trash and I decided to crack one open. Seeing the big transformer gave me the idea to make my own power supply. Currently, my only bench power supply is an old switching ATX power supply that I have added some binding posts to. I’d like an adjustable supply and I know I should probably just buy one, if only for the constant voltage and constant current capabilities, but I figured this would make a nice weekend project.