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Re: [Amps] Switching Power Supplies

To: amps@contesting.com
Subject: Re: [Amps] Switching Power Supplies
From: Steve Thompson <g8gsq@eltac.co.uk>
Date: Fri, 14 Jul 2006 22:24:04 +0100
List-post: <mailto:amps@contesting.com>

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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