[Amps] Switching Supplies for High Current Filaments

[TexasRF at aol.com]

Jim, please bring me up to speed on why the switcher will not work with a  
directly heated tube. I am not challenging the information; just asking for  
enlightenment!
 
73,
Gerald K5GW
 
 
 
In a message dated 10/7/2010 5:00:11 A.M. Central Daylight Time,  
jim.thom at telus.net writes:



--------------------------------------------------
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