Dear All,
John Rabson, F5VLF, is having trouble posting to this group. He asked me to
forward this for him, which he has sent unsuccessfully twice:
---------------
Clank,
The reflector has twice not delivered the attached. Would you try for me,
please?
73
John
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On 23/02/2010 at 14:16 John RABSON <[email protected]> wrote:
From: John RABSON <[email protected]>
To: [email protected]
Date: Tue, 23 Feb 2010 15:51:00 +0100
Subject: Re: LF: VLF_8.79 kHz
My LF ground system consists of nine rods each 1 m long, separated by
about 2 m. if I connect them in parallel the inductance at 980 Hz is
about 7?H, and the resistance is about 25 ohms. This suggests that, at
the frequencies we are considering, this is an essentially resistive
termination and we don't need to cancel out the reactive part.
If we place a similar setup at the other end of a long wire we should see
of the order of 50 ohms. Given that we are working at audio frequency,
perhaps the step-up transformer from 8 ohms could use conventional soft
iron laminations. At 50 Hz, my colleagues used to use a rule of thumb of
20VA per pound of laminations but I can't remember how this figure varied
with frequency.
Can any audio power engineers please comment?
73
John F5VLF
-----------------------
Dr Chris Trayner
School of Electronic & Electrical Engineering,
The University of Leeds,
Leeds LS2 9JT, United Kingdom
Tel: +44 113 34 32053
Fax: +44 113 34 32032
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