Oh my God-Zilla!!!!!!

got the interstage, Jörg worked over the weekend

got the welding power supply (fan makes too much noise, must find something else)

switched it on.

ran it into a resistor.

it runs at 800V 100mA

measured sine waves with the scope and things you generally do

so far so good.

the OPT makes noise too.

that got me worried a bit.

Put an OB on the output.

No noise at all.

no 50Hz, no 100Hz.

Pure silence, amazing.

Maybe something wrong with it.

What the heck, put my Ipod on the input.

I played some Morcheeba.

Pure, no clipping, no deformation, very, very smooth

measured peaks at 26V RMS in 6 ohm, there is some bass in this music, yes....

that is 26 x 26 / 6 = 112W!!!!!!!!!!!!!!!!!!

112W SE!!!!!!!!!!

MEASURING

That's 150mV in, 15V out in the driver stage...

1.6mA in the input stage, 30mA in the driver

measured in a toroidal "interstage" transformer in the plate line.

I know that you don't do that, thanx.

I get a max out from the driver of 100Vrms at 1V in.

Now, that is more than enough!

The problem

the first one.
After the destruction of some resistors.
I was going to use AC for the heater.
16.5V 15Amps.
And I thought that there would be no 50Hz problem.
We all make mistakes.
There was an ENORMOUS 50Hz, well 100Hz actually.
So no AC.
A DC power supply.
Built one, heavy, lots of capacitors.
And fuses.
No good.
So now I'm waiting for a 100Kh switching power supply.
And on the diagram you can see the soft start.

Then there is the coupling.
DC, maybe beautiful, definitely doable but I need to burn another 100Watts or so to match the DC levels.
A capacitor, no.
I didn't like it from the beginning.
Ari told me why, and I'll stick with that.
Not a whole lot of other posibilities left...
An interstage transformer.
Jörg.
Waiting for that too.

THE DIAGRAM

Power supply with the "economy mode" switch

Well preliminary, that is.
But it will look very much like it.
Not 100% sure about the supply voltage for the RS607
Something a bit under 1kV, to keep it safe for the kids ;-))
Not 100% sure about the bias for the grid either.
Depending on it's value you can have more or less maximum power.
But it also means more plate current.
I'll probably make a "turbo" switch.
off 20W SE
on 50W SE

and call it the energy saving button.