Does anyone have a feel for how much delay between key and sidetone is tolerable or comfortable for a competent CW operator? Thank you in advance.
I commonly use a keyer at up and beyond 30WPM, where each dit is about 25ms. It would feel odd to me at least, if a sidetone was more than a dit (25ms) behind. I'm sure I would never ever be able to detect just a few ms.
Note that in many QSK-type transceivers, actual keying is as much as 10 to 30ms behind key closure. See e.g. ARRL rig reviews for keying waveforms. When I switch between different rigs at different sites and the delay changes I can kinda feel "the timing is funny" between key closure and actual TX but I can adapt to delays like this.
Then I can go back to my "true QSK" setup (separate TX and RX, so no IF flopping between modes on each keychange) and I feel "oh this is great, nothing feels weird about this at all, this is the way it's supposed to be."
So I would say a delay of 10-30ms is noticeable but humans can adapt to it.