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Re: LF: RE: Todmorden receiver

To: [email protected]
Subject: Re: LF: RE: Todmorden receiver
From: Paul Nicholson <[email protected]>
Date: Wed, 29 Nov 2017 17:11:48 +0000
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The re-built E-field rx was put outside this afternoon
for a on-air trial.

Pre-amp inside the antenna tube

 http://abelian.org/vlf/tmp/171129a.jpg

I'm a bit worried about noise from light getting
into the tube - the plastic lets a bit of light
through.  I'll probably have to fit an opaque liner.

Here's the power supply, filter and line driver

 http://abelian.org/vlf/tmp/171129c.jpg

I just got finished at dusk

 http://abelian.org/vlf/tmp/171129d.jpg

The antenna looks remote but there's still 140mV RMS of 50Hz
on it.  This doesn't come from the house, or even the overhead
power lines to the house, but from further away.

I'm using a metal support pole and guys - hopefully that means
the calibration won't change so much between wet and dry
conditions.

Here's the spectrum

 http://abelian.org/vlf/tmp/171129e.gif

It seems to be working well, no intermod.  The gain is a little
too high, overall x30 voltage gain from antenna to soundcard
input.  I'll have to drop that to about x15 tomorrow.  It really
doesn't need much gain with a 2m antenna tube 2m off the ground.

--
Paul Nicholson
--

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