Tony King - W4ZT wrote:
> I think this was meant for Steve ;)
>
> Will Matney wrote:
>
>>Tony,
>>
>>What is the waveform coming out? Is it a square wave, or is it a
>>modified sine wave (a stair steeped square wave that supposed to
>>mimick a sine wave)? If it were me, I'd want the square wave, rectify
>>it, and then filter it well. All older modile tube amps worked this
>>way, so did automotive radios that used a vibrator, and later semis
>>to switch with. One needs to rectify it first, then filter it
>>thoroughly the same as any other supply. In your case you'd probably
>>be using a choke instead of a transformer, or will you be switching a
>>transformer? There's several ways to set these up. In any instance,
>>the weight savings is due to using a higher frequency.
I'm aiming for a floating supply as the current project is a tetrode
running with the screen at ground potential. I initially thought about a
dc supply where the switching frequency can be filtered to a minimal
level, but then I thought about using the ac (more or less square wave)
instead for simplicity. Capacitive coupling from the heater to the
cathode is quite high impedance, and the cathode is bypassed to ground
so I figure that the likelyhood of heater voltage getting transferred
onto cathode-control grid bias voltage is low.
Thanks for your private comment too, Will. Sorry I haven't acknowledged
it earlier.
Steve
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