[Amps] 'red' cores versus 43 cores

[Larry Phipps]

Red (-2) material is powdered iron, -43 is a ferrite. Generally speaking, ferrites should only be used for transformers, because they are very lossy when used as an inductor. Powdered iron can be used for inductors or transformers, but because of the much lower permeability, it will be difficult to provide high enough shunt reactance at HF frequencies unless a lot of turns are used. -43  and -61 material overlap somewhat in terms of frequency coverage, with -43 weighted toward lower frequencies. -61 requires more turns, but handles much higher flux levels without saturation. 

73,
Larry N8LP



Date: Sat, 28 Mar 2009 19:27:02 -0700
From: Dan Sawyer <dansawyer at earthlink.net>
Subject: Re: [Amps] 'red' cores versus 43 cores
Cc: Amps <Amps at contesting.com>
Message-ID: <49CEDC76.6060202 at earthlink.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Thanks to all of you for the replies. The first interest is to build and 
test a 300 watt input and output transformer pair.

The reason I chose #43 to discuss was it was mentioned in at least one 
of the Motorola 2 to 30 MHz amplifier app notes. Should #61 be used for 
this purpose? Should the input and output use the same material?

Dan kb0qil