Hi Todd,
I am building the Arduino part as a separate PCB, the ATmega328P plus associated components are going on one PCB with an Si5351 Adafruit board, OLED screen, rotary encoder, buttons, EEProm and beeper attached. This is all currently breadboarded up and working. My PCB is laid out for this part.
The other PCB will just be the Bitx20 with the VFO and BFO wires going from the Arduino board to this one.
I have been experimenting this afternoon - I plugged the Si5351 directly in to the Bitx20 VFO and BFO input points. The VFO I put in at the base of Q7 and the BFO directly in to the T3 mixer, both via a 0.1uF capacitor. The circuit I am using is the one shown on the following blog post:
My initial experiments did appear to work, the signal levels going in to these two places were slightly under the levels when using the original oscillators by approximately 0.2 - 0.3V. I did hear some morse code at around 14MHz but then all the signals appears to fade out for the rest of the day both with the Si5351 and the original oscillators back in place.
I am currently working on getting the PCB laid out for the Bitx20 using surface mount components.
