Return-Path: Received: (qmail 57081 invoked from network); 11 Jan 2005 13:37:24 -0000 Received: from unknown (HELO ptb-spamcore02.plus.net) (192.168.71.3) by ptb-mailstore02.plus.net with SMTP; 11 Jan 2005 13:37:24 -0000 Received: from mailnull by ptb-spamcore02.plus.net with spamcore-l-b (Exim 4.32; FreeBSD) id 1CoMCo-0006rK-1K for dave@picks.force9.co.uk; Tue, 11 Jan 2005 13:37:06 +0000 Received: from [192.168.67.1] (helo=ptb-mxcore01.plus.net) by ptb-spamcore02.plus.net with esmtp (Exim 4.32; FreeBSD) id 1CoMCn-0006rC-5I for dave@picks.force9.co.uk; Tue, 11 Jan 2005 13:37:05 +0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore01.plus.net with esmtp (Exim 4.30; FreeBSD) id 1CoMD3-00071w-Lq for dave@picks.force9.co.uk; Tue, 11 Jan 2005 13:37:21 +0000 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1CoMAK-0003Az-TN for rs_out_1@blacksheep.org; Tue, 11 Jan 2005 13:34:32 +0000 Received: from [193.82.116.30] (helo=relay.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1CoMAK-0003Aq-CN for rsgb_lf_group@blacksheep.org; Tue, 11 Jan 2005 13:34:32 +0000 Received: from hestia.herts.ac.uk ([147.197.200.9]) by relay.thorcom.net with esmtp (Exim 4.43) id 1CoMAG-0001GS-Ua for rsgb_lf_group@blacksheep.org; Tue, 11 Jan 2005 13:34:32 +0000 Received: from altair ([147.197.200.45] helo=altair.herts.ac.uk) by hestia.herts.ac.uk with esmtp (Exim 3.22 #1) id 1CoM9S-0007jX-00 for rsgb_lf_group@blacksheep.org; Tue, 11 Jan 2005 13:33:38 +0000 Received: from [147.197.164.230] (helo=RD40002) by altair.herts.ac.uk with esmtp (Exim 3.36 #1) id 1CoM9R-0002m5-00 for rsgb_lf_group@blacksheep.org; Tue, 11 Jan 2005 13:33:37 +0000 From: "james moritz" To: rsgb_lf_group@blacksheep.org Date: Tue, 11 Jan 2005 13:33:37 -0000 Message-ID: <000001c4f7e2$27ee3a50$e6a4c593@RD40002> MIME-Version: 1.0 X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.4510 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 X-UH-MailScanner: No Virus detected X-UH-MailScanner-From: j.r.moritz@herts.ac.uk X-SPF-Result: relay.thorcom.net: 147.197.200.9 is neither permitted nor denied by domain of herts.ac.uk X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=failed,none Subject: LF: Re: Pre-amps on LF / T/A sigs Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Status: No, hits=0.0 required=5.0 tests=none autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-Spam-Filtered: by PlusNet SpamCORE (v3.00) Dear Joe, LF Group, There is quite a lot of info, including schematics and measurements, on the FT817 RX at: http://www.ussc.com/~turner/ft817_rcv.html This comes to the same conclusion about the LF sensitivity. It is a bit difficult to interpret the sensitivity measurements with/without the preamp, but the sensitivity without the preamp would appear to be about 36dB down at 100kHz compared to HF, and even worse with the preamp on. Since the same mixer transformer is used from 100kHz to 470MHz, it would probably be difficult to do much better with this component than Yaesu have done already. BTW, the QRSS10 sigs from VO1NA have been visible much of the time over the last couple of nights here - with "O" copy for considerable periods. The most consistent times appears to be between about 0600 and 0800 utc here. YU7AR has been a good signal too, about S5. Cheers, Jim Moritz 73 de M0BMU