I’ve done all of those things (shared clock, external triggers) and it got a lot better, but still wasn’t giving me the synchronization I wanted.
I did put it in IQ streaming, and and set it all up with Spike, but again it just didn’t quite get me where I wanted to go.
I bought an SM200 to give a try and see if it’s super-fast sweep time will allow me to make back-to-back spectrum measurements over 100MHz using a switch versus trying to synchronize the two BB60’s.