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From: Dimitrios Tsifakis <dtsifakis@gmail.com>
Date: Sun, 13 Jan 2019 06:57:23 +1100
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To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: a lot of ferrite
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Hi Stefan,

yes, that's me also known as VK1SV but I have changed states and I
have a new callsign now. :-) In fact I have both as I am using VK1SV
at the university for the cubesate ground station that I manage.

I will study these sites today and make up my mind if it's worth doing
this or not.

73, Dimitris VK2COW


Στις Κυρ, 13 Ιαν 2019 στις 12:29 π.μ., ο/η DK7FC
<selberdenken@posteo.de> έγραψε:
>
> Hi Dimitris,
>
> Interesting. BTW, it's a long time ago that we read from you. You have
> been VK1SV some years ago, right?
> I remember your websites and experiments with some long wires laying on
> the ground. I wish to have such a wide area for experimenting like you
> have :-) Recently i searched for one of your websies where you described
> an experiment using 2x 100m of wire, if i remember correctly. But the
> page was not found. Can you tell me the link, if it is still existing?
>
> Well, i see no advantage in a RX antenna when using such rods. Maybe you
> can build a RX loop antenna a bit more compact but then it will be very
> heavy and the air gap (changing with temperature and mechanical forces)
> may affect the phasy stability.
> For a TX antenna i see no advantage either. An AL value of 1 uH can be
> reached with most high mu ferrite toroids...
>
> However, maybe you could build a H field RX antenna for frequencies
> below 1 kHz, something like http://www.vlf.it/romero3/ics101.html or
> http://www.vlf.it/matteobruna/ULF_Induction-Coil.htm
>
> 73, Stefan
>
>
> Am 12.01.2019 04:48, schrieb Dimitrios Tsifakis:
> > 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
> >
> >
>