[Amps] Switching Supplies for High Current Filaments

[Jim Thomson]

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From: "W2XJ" <W2XJ at W2XJ.NET>
Sent: Wednesday, October 06, 2010 9:05 PM
To: <TexasRF at aol.com>; <jim.thom at telus.net>; <amps at contesting.com>
Subject: Re: [Amps] Switching Supplies for High Current Filaments

> This is easy with a switcher. Switching designs include PWM controller 
> chips
> designed for that purpose. They have various external inputs for voltage
> control, current limit, etc. It takes a few small resistors and one cap to
> implement a soft start to ramp up the voltage. Current limiting can also 
> be
> easily implemented on these chips with the correct sensing.
>
> Advantage is a smaller, lighter, cheaper and easier to wind transformer
>

##  The caveat is  you can't use any version of a switcher... when used with 
a
directly heated  [thoriated tungsten]  GG triode.  However, ur scheme would 
work
with directly heated  tetrodes.... like a 4CX-5000.

Jim  VE7RF