Friday, May 22, 2009

30m QRSS-RX/MEPT part 2

The control of the whole beast in planned to be done by a PICAXE-08M. In the present MEPT, this controller generates DC voltage for the modulation of the 5068.8kHz oscillator by means of PWM and a low pass filter. Further the controller delivers a keying signal to the 74HC240 final.
In the future, said controller will also provide a PTT signal, which will switch on the active double and also switch off the grabber's rf-front-end and audio-stage. For regular QRSS or DFCW it would be conceivable to sequence the PTT signal just about the keying, thus having some sort of QSK.