Return-Path: Received: (qmail 14576 invoked from network); 22 Dec 2002 17:31:30 -0000 Received: from netmail02.services.quay.plus.net (212.159.14.221) by mailstore with SMTP; 22 Dec 2002 17:31:30 -0000 Content-Transfer-Encoding: 8bit Received: (qmail 13598 invoked from network); 22 Dec 2002 17:31:22 -0000 X-Priority: 3 Received: from post.thorcom.com (193.82.116.70) by netmail02.services.quay.plus.net with SMTP; 22 Dec 2002 17:31:21 -0000 X-MSMail-Priority: Normal X-SQ: A X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from majordom by post.thorcom.com with local (Exim 4.10) id 18Q9vy-0005xR-00 for rsgb_lf_group-outgoing@blacksheep.org; Sun, 22 Dec 2002 17:30:38 +0000 Received: from [212.125.75.12] (helo=mail4.messagelabs.com) by post.thorcom.com with smtp (Exim 4.10) id 18Q9vx-0005xI-00 for rsgb_lf_group@blacksheep.org; Sun, 22 Dec 2002 17:30:37 +0000 X-VirusChecked: Checked X-Env-Sender: William.Ashlock@edwards.boc.com X-Msg-Ref: server-2.tower-4.messagelabs.com!1040578232!13809 Received: (qmail 5368 invoked from network); 22 Dec 2002 17:30:32 -0000 Received: from unknown (HELO ukfw1.ge.boc.com) (193.131.2.157) by server-2.tower-4.messagelabs.com with SMTP; 22 Dec 2002 17:30:32 -0000 Received: from z-160-100-160-136.est.ibm.com ([160.100.160.136]) by ukfw1.ge.boc.com; Sun, 22 Dec 2002 17:30:31 +0000 (GMT) Received: from exc_wil04.edwards.boc.com ([162.118.144.226]) by exc_cra03.edwards.boc.com with SMTP (Microsoft Exchange Internet Mail Service Version 5.5.2653.13) id YSKVTPPK; Sun, 22 Dec 2002 17:34:20 -0000 Received: by EXC_WIL04 with Internet Mail Service (5.5.2653.19) id ; Sun, 22 Dec 2002 12:30:31 -0500 Message-ID: From: "Ashlock,William" To: rsgb_lf_group@blacksheep.org Date: Sun, 22 Dec 2002 12:30:29 -0500 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2653.19) Subject: LF: RE: Re: Balanced vs. Unbalanced loops Content-Type: text/plain; charset=iso-8859-1; format=flowed X-Spam-Status: No, hits=0.0 required=5.0tests=noneversion=2.42 Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Steve says: >"I have had good results with an ordinary (unbalanced) air-core loop of 10' >diameter. Nulls are approaching 50 db on groundwave signals. The loop uses a >standard single-turn pickup loop out to the rx via 50 ohm coax. I agree with Jan that a preamp is of no value once your limiting noise floor is background sky/atmospheric noise". Jan says: >"As long as the background noise without pre-amplifier is 10-20dB above the background band >noise it is totally vaste to use a pre-amplifier, it may only worsening the result >I already agree to the balance, but using a balanced amplifier for a balanced >antenna is only amateur nonsense." I'm guessing that the only problem we have here is the terminology. Steve says his loop is unbalanced. I would call it 'floating' since the connection to the receiver is an isolated single-turn pickup coil. If he were to connect one side of the main loop winding to the coax shield it would become unbalanced and the performance would be degraded considerably. If the loop is a single winding center-tapped design, a balanced amplifier having three input connections, a +, -, and a common is needed. Call it a differential amplifier if you would like. At my base situation an amplifier is required because I do NOT have the '10db above background' condition, identified above, for my weakest signals. The problem is that there are large 60Hz plus harmonics (buzzz), currents in the ground that my 200ft coax lead-in picks up. I'm thinking of trying a balanced line (oops, here we go again ) per John Andrew's suggestion, in order to eliminate this pickup ......so the need for the amplifier goes away. Bill A _____________________________________________________________________ This e-mail has been scanned for viruses by the WorldCom Internet Managed Scanning Service - powered by MessageLabs. For further information visit http://www.worldcom.com