Cheap Soldering Iron: Which one?

Receiver Build Gone Wrong: Proper Troubleshooting and Accepting Failure

Backpack SDR: A modular QRP SDR Transceiver

Edited 12/13/20 to reflect the move to from Facebook

Today I wanted to post about a new SDR project called “Backpack SDR” that’s taking shape. Since August, Keith Myles, VE3IFT has been sharing pictures of his Backpack SDR transceiver project on the Amateur QRP Radio group on Facebook:

What is the Backpack SDR?

The Backpack SDR is an HF transceiver project that is based on the Teensy 4.0 or 4.1 MCU. It uses as many off-the-shelf parts as it can in order to keep the build simple and also keep costs down. It’s not a budget build, per se, but the basic mono-band Backpack SDR can be built for under $200.

When Keith shared the pictures above, they immediately generated interest, not because the transceiver is particularly a new concept, but because of the way it’s designed. While many projects are monolithic in that the technology is all specific to the project, Keith has designed his Backpack SDR project to make use of modules. In fact, the name “Backpack” refers to its construction, not portability!

Backpack SDR: How hard to build?

With some basic soldering skills, some wiring, and some firmware (as easy as an Arduino sketch, as far as I can tell) an SDR is born. The Receiver module, filters, and 10W PA all come from QRP Labs (see links below) and the rest can be had on either Amazon,, or eBay.

How to Learn More

Are you interested in learning more? First, join the “Keiths_SDR” list.. Instructions, firmware, and assistance are available there. If it looks like something you’d like to do, then the majority (if not all) of the parts are listed below from the three vendors previously mentioned:

Parts List:

PartAmazon Link (or Other)Bangood LinkEbay Link
Instrument Case
200mm x 175mm x 70mm
Instrument Case
Teensy 4.0 (Mono Band)Amazon
Teensy 4.1 (If you're going multi-band)Amazon
3.5" LCD Screen Module TFT 3.5inch SPI Serial 480 x 320 ILI9488AmazonEbay
Teensy Audio Interface BoardAmazonEbay
QRP Labs ModulesReceiver Module

10W HF Linear Amplifier

Ultimate LPF Switch (can be used for BPF too)

Band Pass Filter

Low Pass Filter

Si5351 Breakout board or moduleQRP Labs Si5351 Synth Module

Pin Header KitAmazonBangoodEbay
Right Angle 2x40 Pin HeadersAmazonEbay
Stackable Shield Header KitAmazon
Dupont Wire KitAmazonBangoodEbay
Photoelectric Rotary EncoderAmazonBangood
Mechanical Rotary EncoderAmazonBangood


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  1. You did not mention the control knob.
    I have bought the uSDX kit. It will be my summer holiday project.

    1. You’re right- the knob is missing. But any knob will work, it’s builders choice 🙂

  2. Is there any way to see his Arduino Script? I have avoided using Facebook, for obvious reasons. I would like to see if I can compile his SDR code.

    1. For now, all the info is limited to the Facebook group as far as I know. Perhaps someday it’ll be on github or another repo.

    • KN4FTT on November 24, 2020 at 8:05 AM
    • Reply

    I agree…too bad the code if being hosted on a parasitic site like fb…I s**t canned my fb account two years ago so I’ve asked my brother to go check out this forum is see what code/schematics/etc that he can find! I thoroughly enjoy your site Mr. Flowers!

    1. Thanks for the comment, and I’m glad that my ponderings on my radio meanderings have been enjoyable. Much appreciated!

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