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From: "Phil Allison" <phi...@tpg.com.au>
Newsgroups: rec.audio.tubes
Subject: Re: Mystery transformer
Date: Tue, 30 Oct 2012 13:45:14 +1100
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"GRe"
>
> "Don Pearce"
>>>
>> Could you explain these tests in a little more detail? I'm not sure
>> why the inductance appears to be dependent on the voltage.
>
>
> It's due to hysteresis losses of ferromagnetic materials like the 
> lamination in transformers.


** You have made a big mistake by separating Don's Q from the original 
context.


> Take f.e. a mains transformer and measure the current trough the primary,


** Irrelevant to the falling L value at lower levels in your tests.

 That has to do with falling permeability of the core at low I mags.

 Odds on the core is made of ordinary transformer steel rather than Mu-metal 
or similar.


....  Phil