Steve wrote:
Has anyone out there built a solid state replacement for
the audio output tube in the R-392? If not it would
seem that a power MOSFET, and associated circuitry,
in a tube socket base would be useful.

I'm in the process of building a power supply for
my R-392, and the output tube draws a lot of current.
It'd be nice to do without it.

Steve,

There are some details of the different solid state audio
mods at:

http://www.roveroresearch.com/r392/hints.html

towards the bottom under Solid State Audio