LF: Simple preamp for 8-9kHz

To:	[email protected]
Subject:	LF: Simple preamp for 8-9kHz
From:	Roger Lapthorn <[email protected]>
Date:	Sun, 6 Feb 2011 17:11:17 +0000
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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
G3XBM GQRP 1678 ISWL G11088

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