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Re: [Amps] ferrite in RF chokes for PAs

To: "'AMPS'" <>
Subject: Re: [Amps] ferrite in RF chokes for PAs
From: "Peter Voelpel" <>
Date: Thu, 6 Mar 2008 20:02:43 +0100
List-post: <">>
The better news is that it worked in many thousands of amps  built by
Rohde&Schwarz from about 1958 to 1990 for the military and other gouvernment
The early version was 500W AM/CW/FSK with a single QB5/1750, later 800W
AM/CW/FSK with the same tube, and then the version with the YL1050/RS1072C
built for any mode 1-30MHz and up to 1500W output 24/365.
The YL1050 operates at 3KV up to 1.4A.


-----Original Message-----
From: [] On
Behalf Of Jim Brown

>Plate RF choke has an appreciable DC current component in it. This 
>lowers the effective mu of the ferrite, and makes it less effective as 
>a choke.

YES!  The good news is that this can be predicted from mfr data sheets. 
The bad news is that you probably won't like the prediction. More bad news
-- the DC will also cause heating, very possibly overheating. 

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