From: "Clemens Paul" <cpaul@gmx.net>
To: <rsgb_lf_group@blacksheep.org>
References: <CAKvcm2cJtu=F5yHvR53Vkvf5bb8J1BQVKi9U4g-kupA+6i1=UA@mail.gmail.com> <CAKvcm2e-MyjDe=SJ8K0HhYczVtYCc0n0cSnaZeRHWLSa_TTgwQ@mail.gmail.com>
In-Reply-To: <CAKvcm2e-MyjDe=SJ8K0HhYczVtYCc0n0cSnaZeRHWLSa_TTgwQ@mail.gmail.com>
Date: Sat, 12 Jan 2019 15:17:45 +0100
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Subject: LF: RE: Re: a lot of ferrite
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 Hi Dimitris,

>Minor correction, the calculated relative permeability should be about
>500,

I've made a calculation based on your data with the mini ring-core calculator
and it says µ = 1070 and AL = 937.5nH /N^2

So your first calculation seems to be right.

73
Clemens
DL4RAJ 


>-----Original Message-----
>From: owner-rsgb_lf_group@blacksheep.org 
>[mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of 
>Dimitrios Tsifakis
>Sent: Saturday, January 12, 2019 5:03 AM
>To: rsgb_lf_group@blacksheep.org
>Subject: LF: Re: a lot of ferrite
>
>Minor correction, the calculated relative permeability should be about
>500, I made a mistake in the initial calculation. I just discover why
>they call it initial permeability (bad joke) :-)
>
>73, Dimitris VK2COW
>
>Στις Σάβ, 12 Ιαν 2019 στις 2:48 μ.μ., ο/η Dimitrios Tsifakis
><dtsifakis@gmail.com> έγραψε:
>>
>> Hi LF group,
>>
>> I have managed to acquire a few very large ferrite rods (36 
>cm x 10 cm
>> x 2 cm). The material is unknown but I managed to form a square
>> 'toroid' with four of them (they are heavy so gravity was enough to
>> keep everything in place for a measurement) and I measured 
>about 15 uH
>> for 4 turns at 0.1 MHz, which if I have done the calculations
>> correctly implies a relative permeability of about 1000.
>>
>> The R of the impedance of the square loop was low (<0.2 ohm) at 0.1
>> MHz and it increased fast with frequency (170 ohm at 5 MHz!).
>>
>> The question is, what LF/VLF experiment would you do if you 
>had half a
>> dozen of these rods?
>>
>> 73, Dimitris VK2COW
>
>
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