Thanks Frank.
"low VHF RX mixers for one". I hadn't thought of that.
Re: phase noise in oscs. Agreed: that has been my experience.
Although there is this tendency these modern days to keep everything as small as possible and get maximum functionality per cubic centimeter, the fact that valves (especially those with good RF performance - e.g. those you mention) will readily interface to high impedance circuits, tends to be overlooked. And they will stand more abuse (deliberate or otherwise) before going self-destruct! (As any time-served Radio Amateur will know!
)
Regards,
Al / G8DLH