so ive been lurking on this forum for a while and finally decided to try building my first QRP rig from scratch. going with the Manhattan style construction on a copper clad board, doing a 40m CW transceiver loosely based on the Minima design but ive been borrowing bits from a few different schematics which is probably a mistake but here we are.

the oscillator section seems stable enough, i can hear it on my other radio and it doesnt drift too bad after warmup. but my TX output is way lower than i expected -- im getting maybe 200mW into a dummy load when i was hoping for closer to 500. the IRF510 driver stage is running warm but not scary hot. is this just a biasing issue or should i be looking at the driver transformer winding ratio first? i wound it myself and honestly i lost count at some point and had to guess the last few turns.

also general question -- for portable ops with a battery, whats a reasonable expectation for contacts per amp-hour at these power levels? i know thats kind of a how long is a piece of string question but just curious what others experience

the transformer winding is almost certainly your culprit if you lost count lol. even being off by 2-3 turns on a small toroid can tank your efficiency pretty significantly. i'd rewind it before chasing the biasing rabbit hole, because if the impedance matching is off the FET is just gonna dump heat instead of RF. also check what your gate drive voltage looks like -- the IRF510 needs to be driven pretty hard to get into full enhancement mode and a lot of homebrew designs underestimate that.

on your battery question, honest answer is it depends so much on the band conditions and how often you're actually keying down vs listening. when i was doing SOTA activations with my KD1JV Tribander i was getting maybe 3-4 hours of real operating time on a 3Ah LiPo at 5W, but i wasnt in constant TX obviously. 200mW is going to be very efficient on receive at least so that part works in your favor.

i built something similar last winter and went through basically the same thing. turned out my dummy load was also slightly off which was throwing my power measurements off from the start, worth double checking that too before you assume the rig is the problem. not saying thats whats happening but it bit me and i spent like two weekends chasing a problem that was partly my test setup.