[Amps] Ferrite-loaded plate choke

[Karl-Arne Markström]

Well, 

I have to modify my previous posting somewhat.

This is a most clever way of feeding the HV to the plates,
by using the inductance of the Pi-network coil as both a network component
and as the plate choke...

By using the insulation properties of the Teflon coax, DC HV can be fed to the plate circuit inside
of the coax. independently of the RF potential of the plate, and by using a conventional plate
blocking capacitor between the sheath of the coax and the tubes, the RF current in the tank circuit 
can be made to flow in the proper manner on the outside of the coax sheath.

This certainly goes one step beyond "floating" the whole Pi-network at the plate DC potential 
as was done in the 205J.

73/

Karl-Arne
SM0AOM

----- Original Message ----- 
From: "DF3KV" <df3kv at aol.com>
To: <wc6w at juno.com>; <avilaseca at bluewin.ch>; <Amps at contesting.com>
Sent: Sunday, January 09, 2005 7:28 PM
Subject: Re: [Amps] Ferrite-loaded plate choke


> ---- Original Message -----
> From: <wc6w at juno.com>
> To: <avilaseca at bluewin.ch>; <Amps at contesting.com>
> Sent: Sunday, January 09, 2005 7:03 PM
> Subject: Re: [Amps] Ferrite-loaded plate choke
> 
> 
> >
> >
> > Hi Angel,
> >   Here is a link to an old posting which describes how to use a
> "standard" RF choke with 4CX250's.
> >
> > http://lists.contesting.com/archives/html/Amps/1998-10/msg00480.html
> >
> >   If you fabricate the entire Pi-L coil from RG-402 then the
> effective impedance at the plate choke will be circa 50 ohms.  I am
> using this latter method with a pair of 4CX600's in an amp currently
> under constuction.
> 
> Hi Marv,
> 
> How can the effective impedance at the top of the plate choke be 50
> Ohms,  when the tube output impedance represents for instance 2 KOhm
> at the same connection?
> 
> 73
> Peter
> 
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