DIY

The KM4CFT CFT-1 QRP Transceiver Build

Documenting the build of a CFT-1 QRP CW Transceiver and it's first field use in a POTA activation at Chino Hills State Park.

Brian K6ABR

Brian K6ABR

— 3 min read
The KM4CFT CFT-1 QRP Transceiver Build

I've added a new transceiver to the pile: the CFT-1 QRP CW rig designed by Jonathon KM4CFT. Jonathon is active on the POTA Discord and has been releasing antennas and CW keys and recently released his CFT-1 design. The CFT-1 is available as a kit (with or without pre-wound toroids) and as a completely assembled unit.

After excellent activation reviews by Thomas K4SWL and Evan K2EJT, I started my build of the unit. The kit comes well packed and organized, the PC boards seem to be well engineered and manufactured, and the 3D printed case pieces were perfectly acceptable.

The instructions for the build can be found as a PDF online and are well-written and clear, containing plenty of photos and diagrams. Jonathon has also recorded a helpful video that walks the builder through the calibration process at the end of the build.

Jonathon claims that the kit is intended for an intermediate builder, but with the exception of winding the toroids (which is merely tedious), the kit went together extremely easily and I had no trouble during the process.

During the build I utilized a number of tools, including:

  • Soldering Iron
  • Multimeter w/ grabber test leads
  • Flush Cutters
  • Needle Nose Pliers
  • Wire Strippers
  • Small Screwdrivers
  • Heat gun for shrink tubing
  • Magnifying glass (my eyes are getting old!)
My humble fold-down electronics table in the garage.

For the final calibration of the unit, there are a number of options for completing the process. I ended up utilizing my Yaesu 710 (for the waterfall panadapter), my multimeter with grabber test leads, and my TinySA Ultra as a signal generator. An RF output power meter of some sort is also recommended, but I was able to successfully use the QRP Guys 12w Dummy Load/Power Meter for that step (as seen in the photo below).

The completed and calibrated unit.

After the final assembly and calibration, I was excited to get it on the air and test it out. Fortunately, I was able to get out to Chino Hills State Park (US-1139) for a quick lunchtime activation and test run.

I found the radio to sound great on both headphones and through my small powered speaker. The receiver was quiet, and sounded much like the LNR Precision MTR4B transceiver I once had. While conditions weren't great, I was eventually able to gather a full 10 contacts for a complete activation.

Overall, I'm very happy with the kit and the radio. The receiver sounds good, the signal reports I was receiving were reasonable, and I really like the simple operation menus and controls. Jonathon did a great job designing and kitting this transceiver. I recommend it to anyone with an interest in QRP CW!

Current Chino Hills State Park Score: K6ABR: 4, Current Park Leader: 61

Read more