Return-Path: Received: (qmail 79355 invoked from network); 10 Jan 2005 12:24:38 -0000 Received: from unknown (HELO ptb-spamcore02.plus.net) (192.168.71.3) by ptb-mailstore02.plus.net with SMTP; 10 Jan 2005 12:24:38 -0000 Received: from mailnull by ptb-spamcore02.plus.net with spamcore-l-b (Exim 4.32; FreeBSD) id 1Cnyaf-000BSV-H4 for dave@picks.force9.co.uk; Mon, 10 Jan 2005 12:24:11 +0000 Received: from [192.168.67.1] (helo=ptb-mxcore01.plus.net) by ptb-spamcore02.plus.net with esmtp (Exim 4.32; FreeBSD) id 1Cnyaf-000BSQ-Ct for dave@picks.force9.co.uk; Mon, 10 Jan 2005 12:24:09 +0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore01.plus.net with esmtp (Exim 4.30; FreeBSD) id 1Cnyb6-0007ms-3B for dave@picks.force9.co.uk; Mon, 10 Jan 2005 12:24:36 +0000 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1CnyaG-0007KB-Eu for rs_out_1@blacksheep.org; Mon, 10 Jan 2005 12:23:44 +0000 Received: from [193.82.116.30] (helo=relay.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1CnyaG-0007K2-3C for rsgb_lf_group@blacksheep.org; Mon, 10 Jan 2005 12:23:44 +0000 Received: from virus-out-st.online.no ([193.212.240.200] helo=scan.telenor.net) by relay.thorcom.net with esmtp (Exim 4.43) id 1CnyaB-0004fh-Gj for rsgb_lf_group@blacksheep.org; Mon, 10 Jan 2005 12:23:44 +0000 Received: from tns-fbu-22-208.corp.telenor.no ([134.47.162.90] [134.47.162.90]) by scan.telenor.net with ESMTP for rsgb_lf_group@blacksheep.org; Mon, 10 Jan 2005 13:23:16 +0100 Received: from tns-fbu-22-213.corp.telenor.no ([134.47.162.191]) by tns-fbu-22-208.corp.telenor.no with Microsoft SMTPSVC(5.0.2195.6713); Mon, 10 Jan 2005 13:23:10 +0100 Received: from TNS-FBU-2E-014.corp.telenor.no ([134.47.163.124]) by tns-fbu-22-213.corp.telenor.no with Microsoft SMTPSVC(5.0.2195.6713); Mon, 10 Jan 2005 13:23:09 +0100 X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 Content-class: urn:content-classes:message Date: Mon, 10 Jan 2005 13:23:08 +0100 Message-Id: Thread-Topic: LF: Re: Pre-amps on LF thread-index: AcT3ASv2F3pFh80tROGFTKVzNCQdvwADbymQ From: jan-martin.noding@telenor.com To: rsgb_lf_group@blacksheep.org X-OriginalArrivalTime: 10 Jan 2005 12:23:09.0187 (UTC) FILETIME=[25143D30:01C4F70F] MIME-Version: 1.0 X-SPF-Result: relay.thorcom.net: 193.212.240.200 is neither permitted nor denied by domain of telenor.com X-Spam-Score: 0.2 (/) X-Spam-Report: autolearn=no,FORGED_RCVD_HELO=0.05,NO_REAL_NAME=0.178 Subject: SV: LF: Re: Pre-amps on LF Content-Type: text/plain; charset=iso-8859-1; 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=0.3 required=5.0 tests=NO_REAL_NAME 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) Even 1N4148 doesn't add more attenuation than a fraction of dB. so I really doubt the statement, the only real problem is possible intermodulation 73 Jan-Martin, LA8AK -----Opprinnelig melding----- Fra: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org]På vegne av Claudio Pozzi Sendt: 10. januar 2005 11:46 Til: rsgb_lf_group@blacksheep.org Emne: Re: LF: Re: Pre-amps on LF On Saturday 08 January 2005 17:48, Joe Craig wrote: > Dear LF Group, > > Getting back to the FT-817, is it possible to > modify the front end or first mixer so that > a preamp would be unnecessary? Many RTX uses inexpensive diodes in the front-end design, for bandpass filter and preamp and attenuator switching. Also if they used more expensive PIN diodes those devices are not the best switching devices for LF. A 100 kHz PIN diode switching devices require a minority carrier lifetime of few ten's of microseconds. If the life time is shorter the diodes acts as a rectifier, not as a switch. I don't know many PIN diodes useful in LF band. So I think that the problem is not in the mixer but in band switching devices. 73 de Claudio, ik2pii -- Claudio Pozzi - Happy Linux User - http://www.qsl.net/ik2pii -- Email.it, the professional e-mail, gratis per te: http://www.email.it/f Sponsor: Migliaia di manuali e guide scaricabili su: Office, Webmaster, Internet, Windows e non solo...clicca qui Clicca qui: http://adv.email.it/cgi-bin/foclick.cgi?mid=2731&d=10-1