Hi
The phase noise numbers for the RFzero was recorded subject to a 50 ohms load, i.e. no additional 74xx buffer stage:
100 Hz -103 dBc/Hz
1 kHz -128 dBc/Hz
10 kHz -136 dBc/Hz
100 kHz -138 dBc/Hz
1 MHz -144 dBc/Hz
at 9 MHz. From
Denis, G0OLX, uses an RFzero generating ~100 MHz driving the GB3SEE 24 GHz beacon. The frequency shifting, not the CW-FSK, comes from Denis walking around the lab (Doppler), and the fact that the FT-817 is xtal controlled. Given the x240 multiplication the phase noise is not bad. OK not tuning to the sides, but still good audio. Like any other RF circuits also the Si5351A needs a good home to do its best.
Bo
Bo, OZ2M