My New SDR-like 20m Polar Modulated Radio is Almost Here!

I obviously haven’t been posting much lately, but I have been working on a new radio design for about the past 12 months. I switched from class K amplifier to class D for more efficiency at lower voltages, and to take advantage of a nifty TI part, the LMG1210.

https://www.ti.com/product/LMG1210

This should enable me to output about 320 watts peak off a single 6S LiPo battery. I coughed up the tariffs and ordered it from JLCPCB back in June. It should be here next week!

Interestingly enough, this polar modulation technique I’ve been using for years is back in the news! https://www.flexradio.com/faq/what-is-aurora/

I think I also found a neat trick to control the whole thing from a Pico 2, significantly reducing the cost of the design.

https://datasheets.raspberrypi.com/rp2350/rp2350-datasheet.pdf

Knowing how sensitive polar modulators are to VSWR, I added a little 1-port VNA and automatic antenna tuner. Not a great one, but enough to take 2:1 down to 1.4:1, which is pretty safe.

Since I want to use this for Parks on the Air and Summits on the Air, antenna setups may vary by location. The whole thing, radio, Arborist throw line, antenna, and battery, should weigh about 5 pounds I think. Hoping to be on the air with it by late summer!