I was thinking of using a toroid to provide the LO injection
to a balanced mixer, using a trifiliar wound transformer
driven by a cathode follower. Has anyone tried that scheme?
On the other hand, adding a cathode follower means that
stage could also be used as a phase inverter and the drive
taken from the cathode and plate, eliminating the need for
a broadband transformer. Anyone have experience with
either means?

Pete