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Date: Sun, 6 Feb 2011 17:11:17 +0000
Message-ID: <AANLkTin2cGO3pSvjSHRdkvXUE+1twgVAT+A4C9pKjsr-@mail.gmail.com>
From: Roger Lapthorn <rogerlapthorn@gmail.com>
To: rsgb_lf_group@blacksheep.org
DomainKey-Status: good (testing) 
Subject: LF: Simple preamp for 8-9kHz
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The schematic of my very simple tuned preamp used to copy DK7FC/P on 8.97kHz
today is available at
http://dl.dropbox.com/u/15047843/9khz_preamp_ggate_g3xbm.jpg . I
unsuccessfully tried to post it here, but despite the small file size it was
rejected twice as spam. No idea why.

The preamp uses an MPF102 in grounded gate (low input impedance) with a
drain circuit tuned to 8-9kHz. This is fed via a 2N3904 emitter follower
into the PC soundcard. All is powered by a small PP3 9V battery. Current
drain is 16mA.

My 80sq m untuned vertical wire loop (also used tuned on 136/500kHz) is in
the back garden and fed with about 10m of coax into the front bedroom shack
and into this small preamp and PC. No attempt has been made to optimise this
- it just works.

I hope this is of interest to some here.

73s
Roger G3XBM

-- 
g3xbm-qrp.blogspot.com/
www.g3xbm.co.uk
www.youtube.com/user/g3xbm
<http://vlf_grabber>G3XBM   GQRP 1678    ISWL G11088

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The schematic of my very simple tuned preamp=20
used to copy DK7FC/P on 8.97kHz today is available at <a href=3D"http://dl=
.dropbox.com/u/15047843/9khz_preamp_ggate_g3xbm.jpg">http://dl.dropbox.com=
/u/15047843/9khz_preamp_ggate_g3xbm.jpg</a> . I unsuccessfully tried to po=
st it here, but despite the small file size it was rejected twice as spam.=
 No idea why.<br>
<br>The preamp uses an MPF102 in grounded gate (low input impedance) with=
 a drain circuit tuned=20
to 8-9kHz. This is fed via a 2N3904 emitter follower into the PC=20
soundcard. All is powered by a small PP3 9V battery. Current drain is 16mA=
.<br><br>My 80sq m=20
untuned vertical wire loop (also used tuned on 136/500kHz) is in the back=
=20
garden and fed with about 10m of coax into the front bedroom shack and=20
into this small preamp and PC. No attempt has been made to optimise this
 - it just works.<br clear=3D"all">
<br>I hope this is of interest to some here.<br><br>73s<br>Roger G3XBM<br=
 clear=3D"all"><br>-- <br><a href=3D"http://g3xbm-qrp.blogspot.com/" targe=
t=3D"_blank">g3xbm-qrp.blogspot.com/</a><br><a href=3D"http://www.g3xbm.co=
.uk" target=3D"_blank">www.g3xbm.co.uk</a><br>
<a href=3D"http://www.youtube.com/user/g3xbm" target=3D"_blank">www.youtub=
e.com/user/g3xbm</a><br><a href=3D"http://vlf_grabber" target=3D"_blank"><=
/a>G3XBM=A0=A0 GQRP 1678=A0=A0=A0 ISWL G11088<br>

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