I have never really been happy with the waveform when I compare it to others that I see, its only a little thing and you need to look close to see it but it has little steps sometimes in the freq (very small part of a hert about 1/10^thPaul,
You mean 0.1Hz?
I wonder how you see that reliably?
Exactly when do you see the variations? On a constant carrier or as the frequency changes?
Presumably it is due to the reference crystal shifting frequency?
That is far less likely with a TCXO, separate oscillator, but possibly small shifts are normal with a standard Si5351-driven crystal.
There have been discussions about the reason, I favour tiny shifts in the crystal loading, but temperature effects can occur.
73 Alan G4ZFQ