so i finally finished my first qrp rig, been working on it on and off for like three months. its a 40m CW transceiver based on the speakerphone design from one of the SPRAT issues, cant remember which one now. runs about 2 watts out into a 50 ohm load which i was honestly pretty happy with for a first build.

the hardest part for me was winding the toroids, i kept losing count of the turns and had to redo the main transformer twice. also had a weird oscillation issue in the rx chain that turned out to be a grounding problem, took me forever to track that down with my little DSO. but once i sorted all that out it just... worked. made my first contact with it last weekend, guy in michigan and im in ohio so not a huge distance but on 2 watts with a wire in a tree i was pretty stoked about it.

anyway just wanted to share i guess, and if anyone has tips for improving efficiency on these little rigs id love to hear them. im getting maybe 60-65% efficiency which seems okay but ive seen people talk about getting higher than that

congrats on the first contact, thats always a special feeling no matter the distance. dont sell yourself short either, 2 watts into a compromised antenna over any path is something to be proud of.

for efficiency on qrp rigs the biggest gains usually come from the driver stage and how well matched your final is to the antenna system. a lot of homebrew designs run the final transistor a bit conservatively for reliability which eats into efficiency. if your using something like a 2n2222 or similar in the final you might try tweaking the bias point slightly, but go slow and watch your current draw. also worth double checking your low pass filter, a poorly tuned lpf can rob you of power too. 65% isnt bad for a first build honestly, some commercial rigs dont do much better. whats your PA transistor?

that toroid winding struggle is so real, i basically destroyed half a bag of t50-2 cores on my first kit lol. i use a clamp now to hold the core while i wind, makes it way easier to keep track. also started marking every 5th turn with a sharpie on the wire before i wind which sounds silly but it works

nice work getting it on the air