[Amps] 'red' cores versus 43 cores

[Alex]

Hi guys:
I would like to point out a few things
1) The color coded cores pertain specifically to Micrometals. They are
intended for inductors, not transformers and the color code indicates for
what frequency range they are intended in order to provide maximum Q. For
transformers they should be used at relatively low power levels.
2) Cores for transformers are for the most part ferrite material and they
have a much higher initial u factor. The high frequency cores rely more on
transmission line characteristics, with the core being there only to
increase the fringing inductance at the low frequency end of the range.
3) Usual u ranges are 120 for the HF range, about 15 to 25 for low VHF (6
meters or so) and about 10 for UHF (100 to 500 MHz).
What is more important is the core loss, lower in ferrites and the ability
to withstand the volts/second stress at the frequencies of interest.
73 and all the best:
Alex	4Z5KS


-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf Of Carl
Sent: Sunday, March 29, 2009 3:15 PM
To: dansawyer at earthlink.net
Cc: Amps
Subject: Re: [Amps] 'red' cores versus 43 cores

You are providing almost no information.

What do you mean by a 300W input and output pair? Is the power level the 
same for both? I see below that you referenced a Moto app notes so we 
finally find out this is for SS.

Why would you want to deviate from their parts list? You havent even 
mentioned a frequency yet.

Try and be a bit more free with info. Youre reminding me of my 21 year 
old son whenever I ask a question....it takes forever to get the full 
answer.

Carl
KM1H


----- Original Message ----- 
From: "Dan Sawyer" <dansawyer at earthlink.net>
Cc: "Amps" <Amps at contesting.com>
Sent: Saturday, March 28, 2009 10:27 PM
Subject: Re: [Amps] 'red' cores versus 43 cores


> 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
>
>
> Dan Sawyer wrote:
>> Is there a straightforward practical or operational description of 
>> the
>> difference between 'red' cores and 43 material. The magnetic 
>> differences
>> are large. However, the 'red' cores are used in low power mixers and 
>> the
>> 43 cores are used in rf power transformers for similar frequency 
>> ranges.
>>
>> What would happen if a mixer were made from a 43 core?
>> What would happen is an output transformer were made from 'red' 
>> cores?
>>
>> Thanks Dan kb0qil
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