so i finally finished my first scratch-built transmitter, been working on this 40m CW rig for like three months off and on. based loosely on the EMRFD designs but i kind of went my own way on the PA stage because i couldn't find the exact transistors they called for and just used some 2N3553s i had in the junk box.

thing actually keys up and i can hear myself on the receiver so that part works. output is somewhere around 2-3 watts which is less than i wanted but whatever, its a start. the problem is when im monitoring on a separate rx there's this kind of splatter or maybe chirp, hard to describe — sounds almost like the note isnt clean when i first key down, like there's a little glitch at the start of each element. keying waveform maybe? i dont have a scope right now which is making this harder to troubleshoot

also the whole thing runs pretty warm even at those power levels which makes me think the transistors arent biased right or the impedance matching into the PA is off. anyone been through something similar with a homebrew TX? especially curious if the key clicks and the heat are related or two totally different problems

the chirp at the start of each element is almost certainly your keying waveform yeah. if you're just hard-switching the oscillator or the PA without any shaping circuit you'll get that every time. classic thing that catches first-time builders. what you want is a simple RC network on the keying line to shape the rise time, something in the range of 5ms rise is usually enough to clean it up without making the dits sound mushy. EMRFD covers this if you dig into the keying chapter, but theres also a ton of stuff in the old QST technical notes about it.

the heat issue is probably separate. what's your bias point on the 2N3553? if you're running it class A at those power levels it'll get toasty. class C would be more efficient for CW but you'd need to think about how that interacts with your keying. without a scope it's rough but you can at least measure the quiescent current at the collector and compare to the datasheet recommendations, give you a clue whether the bias is way off

ive had almost the exact same problem with a little 80m rig i built last winter, the key click thing drove me insane for weeks. turned out for me it was partly the shaping but also i had the oscillator running all the time and just keying the PA, and there was still enough of a transient getting through to cause the glitch. ended up adding a small relay to mute the rx during tx which helped a lot for monitoring but didnt fix the actual chirp obviously lol

3 watts on 40m with a decent antenna is actually pretty usable btw, dont get discouraged. ive worked a bunch of states with less than that running QRP CW