when using FLdigi 's serial port KEYING function....it seems to change whatever the CW PITCH was before, and move it up to 1500 hertz... to get it back to a desired PITCH 3 plugins are used to RE-CREATE the FLdigi CW audio note output...
SINE WAVE GENERATOR
ZAMGATE (in sidechain mode)
CALF FILTER in bandpass mode
the sine wave does not go through zamgate, until the 1500 hz CW AUDIO output of FLdigi 'keys' ZAMGATE's 2nd input port(sidechain port) the rise & fall time are put onto the sine wave note passing through zamgate by the ATTACK & RELEASE controls of zamgate... however, the wave shape exiting from zamgate is trapezoidal and has edge noise on it....so a post bandpass filter is adjusted to take as much of that edge noise out as desired...