Return-Path: Received: (qmail 11726 invoked from network); 24 Apr 2001 18:48:46 -0000 Received: from unknown (HELO murphys-inbound.servers.plus.net) (212.159.14.225) by excalibur.plus.net with SMTP; 24 Apr 2001 18:48:46 -0000 Received: (qmail 27788 invoked from network); 24 Apr 2001 18:48:34 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by murphys with SMTP; 24 Apr 2001 18:48:34 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.16 #2) id 14s7mV-0000aS-00 for rsgb_lf_group-outgoing@blacksheep.org; Tue, 24 Apr 2001 19:43:23 +0100 Received: from cmailg4.svr.pol.co.uk ([195.92.195.174]) by post.thorcom.com with esmtp (Exim 3.16 #2) id 14s7mR-0000aN-00 for rsgb_lf_group@blacksheep.org; Tue, 24 Apr 2001 19:43:19 +0100 Received: from modem-69.lyre-tailed-anthias.dialup.pol.co.uk ([62.137.39.69] helo=g3aqc) by cmailg4.svr.pol.co.uk with smtp (Exim 3.13 #0) id 14s7ly-0005pT-00 for rsgb_lf_group@blacksheep.org; Tue, 24 Apr 2001 19:42:50 +0100 Message-ID: <001501c0cce5$fde69ca0$4527893e@g3aqc> From: "Laurie Mayhead" To: rsgb_lf_group@blacksheep.org Subject: LF: Pre-amps. Date: Tue, 24 Apr 2001 18:41:54 +0100 MIME-Version: 1.0 Content-Type: text/html; charset=windows-1252 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4133.2400 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: Content-transfer-encoding: 8bit

Hi All,

I have been thinking about weak signals on 136 using QRS and DFCW. These techniques enable signals to be read which are buried 30db down in the noise(see Extreme narrow bandwidth techniques ON7YD ) Does this mean that signals 30db down on atmospheric noise are seen,if so what about the noise from the RX pre-amp ? In my case this is about 20/30 db less than the Ant. noise,so would I be looking at the pre-amp noise or is this also reduced by the narrow bandwidth ?

I should like to improve the noise performance of my pre-amp.

filter combination. and would appreciate any information on high performance circuits or amp. units. Is the MAR6 likely to be worth while.

By the way if my thoughts are correct this may be why high Q loops are reported to be superior to lower Q types, higher signal output overriding amp. noise. Any ideas ? 73s Laurie.