[Amps] SMPS use in tube based amps

[Ben Burkhart]

Hi:
    I am looking to make / cook-up a home brew amplifier as both a rite of
passage and to challenge myself. My main use is portable as I have no QTH
at this time. I have a Flex 1500 and enjoy using it, but would like a bit
more than QRP at times. With tube prices really high 3CX800 (Hi-HI) are at
this time I would like to use possibly a GI-46B or GI-7BT in a grounded
grid configuration. Hence the need for a lightweight power supply for 2.2kv
@ 400ma. Some or most of the transformers I have found are in the 40LBS+
range and are a little heavy for portable use.

    I am a networking engineer by trade with a bit more than basic under
standing of electronics. I have been looking at several amplifier designs
by several different people / companies and came across an observation thus
my question. Why are all B+ power supplies simple linear setups?  Why not
use a switch mode power supply? I have yet to see one in a tube based
amplifier. SMPS would allow for better power factor, smaller size and w
eight, better B+ regulation, smaller filtering capacitors.

   I wouldn't really accept the idea that SMPS designs are more complicated
as they are well understood and documented. I have the idea that the
fundamental switching or voltage feedback freq would wind up in the output
but with a properly low pass filter that should not be an issue. So the
question is: Does the amateur community use linear supply as it has always
been this way or am I missing something.

Ben Burkhart
KJ4CGX