Message-ID: <3AE6C6A2.C937F32F@usa.net>
Date: Wed, 25 Apr 2001 14:44:18 +0200
From: "Alberto di Bene" <dibene@usa.net>
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To: "LF Mailing List" <rsgb_lf_group@blacksheep.org>
Subject: LF: Re: Loop preamps
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Hi all,

I am having quite good results with this sort of setup :
my loop is 8 turns, square, 2.2m each side, completely 
isolated from ground and from the feeding coax. 
The loop is connected only to the primary winding on a 
high-mu ferrite toroid ( > 2000), only 3 turns.
The secondary winding is 15 turns, and is connected to the
coax. The inductance of the secondary is such that it resonates
at 137 kHz with 1900 pF. The coax itself provides about 1400 pF
of capacitance, and the remaining 500 are provided by a variable
capacitor, in the shack ! The shack end of the coax is connected 
also to a fet-input preamp (J309), with high input Z.

This setup has the advantages that the tuning is done in the shack,
and also the preamp is in the shack. Moreover, being the loop 
itself electrically isolated from ground and from the feeding coax,
is mostly insensitive to the electric field component of locally 
generated QRN and statics.

Anybody else using such an arrangement ?

73  Alberto  I2PHD