[Amps] (Perhaps) A plate choke too far ...

[Radio WC6W]

Hi Angel,
  The point was to make a rather high value (1-2mHy) choke with no resonances in the HF region.

  The saturation gotcha was a by-product.

  A rod wouldn't suffice in this application.  A gapped core might.  The gap would need to be only a few thousand's wide and I don't have a diamond saw like that...   Too bad pot cores aren't made in 43. 

73 & Good morning,
  Marv WC6W

http://wc6w.50webs.com/

--- On Wed, 1/13/10, Angel Vilaseca <avilaseca at bluewin.ch> wrote:

> From: Angel Vilaseca <avilaseca at bluewin.ch>
> Subject: Re: [Amps] (Perhaps) A plate choke too far ...
> To: "Radio WC6W" <wc6w_amps at yahoo.com>
> Cc: amps at contesting.com
> Date: Wednesday, January 13, 2010, 11:11 PM
> If avoiding saturation is the point,
> how about using a ferrite rod 
> instead of a toroid?
> Or using a toroid but cutting a small gap into it (with an
> abrasive disc)?
> 
> Angel Vilaseca HB9SLV
> 
> Radio WC6W a écrit :
> >    The other day, just for fun, I swept a
> bunch of ol' RF chokes -- solenoid wound, pie wound,
> etc.  All of them exhibited nasty resonances somewhere
> within the HF spectrum.
> >
> >    I then wound a few experimental coils on
> some toroids and one on a type 43 core worked exceptionally
> well -- very flat response with no resonances anywhere below
> 50 Mhz.  
> >
> >    The only gotcha with this part is that in
> a real world application the DC plate current would saturate
> the toroid, killing the mu & the uH's.
> >
> >    Now here's where this concept crosses
> over in the silly side...
> >
> >    The saturation problem could be overcome
> by running an out of phase DC current, servoed by the plate
> I, through a 2nd winding on the core.  This second
> winding would need to be RF isolated with a choke of its own
> but, for a single turn winding a 10uH (air core) choke would
> be sufficient.  The required single turn current would
> be on the order of 10-15 amps.  Sounds bad but, no real
> voltage is required -- 10 Amps at .1 volt is only a
> watt.  In a fortunate circumstance, this current might
> be obtained "free" in series from a DC heater supply.
> >
> >    Searchin' around the all knowing internet
> only uncovered a similar scheme to cancel the plate DC in an
> "audiophile" single ended output transformer. 
> >
> >    Has anyone ever see this done?
> >
> > 73 & Good evening,
> >    Marv WC6W
> >
> > http://wc6w.50webs.com/
> >
> >
> >
> >
> > *
> >
> >
> >       
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> >   
> 
>