Message-ID: <56EAF20F.7050008@abelian.org>
Date: Thu, 17 Mar 2016 18:06:07 +0000
From: Paul Nicholson <vlf0403@abelian.org>
User-Agent: Mozilla/5.0 (X11; Linux i686; rv:17.0) Gecko/20130329 Thunderbird/17.0.5
MIME-Version: 1.0
To: rsgb_lf_group@blacksheep.org
References: <56E526C8.5010401@abelian.org> <1536f9e8813-7821-7aea@webprd-m99.mail.aol.com> <CAC+C6w4XJy+WKnEf47ETU_peN278dPeGRyE=MBy6NwUY-zt8EA@mail.gmail.com> <56E5DCEF.4050905@abelian.org> <56E7090D.4090601@tiscali.co.uk> <56E7122E.1090907@abelian.org> <016f01d17e34$65318b80$2f94a280$@comcast.net>
In-Reply-To: <016f01d17e34$65318b80$2f94a280$@comcast.net>
Subject: Re: LF: EbNaut from Todmorden
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org
Status: O


I tried the long wire at ELF - it was useless.  No Schumann and
it can't see transients from TLEs.    In fact it was pretty poor
at VLF which probably shows how well it couples to the trees.
So, not a very good antenna.

I took it down.

I spotted a place where I could probably put up 200m of wire
at about 8 metres, clear of any trees.   It's further from
the house though so would need a long coax to reach.  I can
borrow some scaffold poles from a neighbour.  Not too far from
a muddy spring (we have plenty of those) for a good RF ground.
I'll need to buy some coax and some proper antenna wire.

Stefan wrote (a week ago):

 > A T200-2 can be used for 1 kW ...

A couple of those will arrive this week.

Also was inspired by something that Andy posted recently
about PAs powered from rectified mains.  Somewhere in the shed
there's a mains isolating transformer and a nice variac.

I've a vague recollection that someone on the list said that
you don't need an NoV for an earth antenna?  Can anyone recall?

I could run a wire for a km across the moors and terminate it
in a bog.  There's an industrial audio amplifier in the shed
which is good for 4kW.   Such a long earth loop would need
quite a high driving voltage.  Also in the shed is a big toroidal
transformer, about 20cm diameter by 10cm thick, which might
make a hefty audio transformer if the material is up to it.

...

I dug the big toroid out.  It has two windings, 400 turns
giving 0.98H and 10 turns of 2cm wide copper strip for 395 uH.
So about 6.17uH/turns^2.   At 8270Hz 2.44V in gives 101.6V out.
The amplifier is too heavy for one person to lift so I can't
try it into the xfmr until an unsuspecting friend comes to visit.

--
Paul Nicholson
--