On Mar 4, 7:20�pm, JIMMIE wrote:
Ive been playing around with some old UPSs that �are the switch mode
type, the ones �without the big iron transformers. I m not sure if I
have a handle on how they work or not but it seems very similar to �a
Class D amplifier amplifiying a 60HZ input, well sort of. It seems
like they dont actually input a 60Hz signal rather they just go
directly from digital by generating the pulse width modulated
waveforms with a computer. I was thinking that a transformer might be
placed before the output low pass filter to step up the voltage for
tube circuits, maybe even a TX PA. No doubt for this to have any merit
the LPF would have to be redsigned.

Jimmie

There are a number of different topologies. One is to convert the
120VAC to 167VDC and then chop it up, usually 20khz and feed that to
transformers to convert to the desired voltages, and then rectify and
filter it once again to get the DC outputs.

The utility of a SMPS is the efficiency, and the light wieght.
Efficient because it operates class D and light because the magnetics
at high frequencies are much lighter than 60hz.

The downside of SMPS is the electronics are rather complex, and the
magnetics are hard to (for me) design.

I don't see any reason you could not modify a SMPS to get a couple KV
for Tube operation. Seems I remember someone advertising a SMPS
capabible of KV output, but I can't put my hands on it. Keep in mind
that a SMPS will tear up you receiver all up and down the bands unless
it is very well designed to eliminate noise.

I use a commercial 50VDC 22AMP SMPS to run my 600 watt solid state
amp.

73 Gary N4AST