[Amps] Ferrite-loaded plate choke

[Karl-Arne Markström]

My understanding of this circuit is that it connects the HV at the output end
of the Pi-network, which gives a much lower impedance level for the choke.

The drawback is that the Pi-network capacitors have to carry both the DC potential
and the peak RF voltage.

The concept was pioneered, if memory serves me right, in the Collins 205J 45 kW servo-tuned 
linear amplifier designed for the SAC air-ground and point-to-point networks, 
(a write-up is in the first edition of the Single Sideband Principles and Circuits).

These amplifiers with their 4 paralleled 4CX5000A's are by the way truly awesome creatures...

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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