Hi Brian --
Thanks for that info. I've used the PT5101 several times without any
problems, but admittedly not in a low-level analog system. It is a
complete switcher in a rectangular package about the size of an ordinary
heatsink. It's definitely pricey, but if the noise isn't too bad, it
makes a nice solution (FWIW, I've used an LM-2577ADJ DC-DC regulator to
generate 20 volts from 12 volts for the LO brick in my 10GHz transverter,
and with a bit of inductive filtering the switching sidebands are better
than -50dBC).