Trying To Transmit

A project log for PortableSDR

Fully stand-alone HF (Shortwave) Software Defined Transceiver & Vector Network Analyzer. Designed for rugged portable use. Highly hackable.

Michael R ColtonMichael R Colton 11/06/2014 at 15:270 Comments

I shot this before the Final Overview Video, but didn't get around to posting it. Basically, it shows that my first attempt at an amplifier board for the PSDR2 was unsuccessful, also, I need filtering. I think that what I showed in the video might not have been that meaningful because I had already damaged the amp at that point. Nevertheless, it seems that filtering before the amplifier is going to be required. I have a circuit I want to try that would be a digitally variable low-pass filter. I think it will work, just not sure if will work at RF frequencies.

I was also lucky to bump into a pretty seasoned RF engineer and picked his brain about designing this amplifier (I only picked the surface though, since I could only take about 5 minutes of his time) basically, it sounds like MMICs will probably only get me to 1 W. Which is not terrible. Beyond that, I'll probably have to design a discrete circuit. BUT he also suggested a trick I'd read about, where you use a power splitter, then, say, 5 MMIC amps, then a combiner, and there you go. I'm interested in trying that. That would also make it easy to step down power, and even provide some redundancy...

THANK YOU SO MUCH EVERYONE FOR DOING THE SURVEYS! I've received over 600 responses! (500 today alone, thanks to being featured on the front page. Thanks Brian!) Next time I'll give a breakdown of the responses and what it will mean for the PSDR moving forward.