Topband: FT-240-77 Toroid Impedance R + jX Components

[Chuck Hutton]

Yes, different sizes of the same mix have different properties and some of
the Amidon charts show that clearly with overlaid data so there's no
surprise there.

But that wasn't really intended to be my question. What I don't have a
handle on is how to use the Fair-Rite u's and u"s data to predict your
measured curves (at least roughly).

Equally perplexing to me is the difference between the curves on your web
page and the Fair-Rite curves in Figure 22 on p. 181. The Fair-Rite curves
have nice peaks that change frequency dramatically as the number of turns is
changed. The peak in your curves doesn't appear to move at all as the # of
turns changes from 1 turn to 6.

Thanks for the comments so far, and I hope you're not out of gas on this
topic.


Chuck

-----Original Message-----
From: Michael Tope [mailto:W4EF at dellroy.com] 
Sent: Monday, December 27, 2004 7:33 PM
To: Chuck Hutton; topband at contesting.com
Subject: Re: Topband: FT-240-77 Toroid Impedance R + jX Components

Hi Chuck,

Yes, you are quite correct that the data on page 173 is not
consistent with my data. I think your observation confirms K9AY's
cautions about over-generalizing useful frequency range based
soley on the type of material. The curves you refer to on page
173 of the Fair-Rite Products catalog are for a very tiny two-hole
binocular core (.136" x .093" x .079"), whereas my data was
taken from a 2.4" O.D. toroid. If you look at the complex
permeability curves for type 77material on page 16 of the
catalog, you'll see that they are more or less consistent with
my data (flat permeability up to about 1 MHz and then roll-off
with permeability above 1.4 MHz dominated by the resistive
component). The data on page 16 were obtained via
measurement of an 18 mm (0.7" O.D.) toroid.
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