Return-Path: <owner-rsgb_lf_group@blacksheep.org> Received: (qmail 82934 invoked from network); 10 Jan 2005 10:42:07 -0000 Received: from unknown (HELO ptb-spamcore02.plus.net) (192.168.71.3) by ptb-mailstore02.plus.net with SMTP; 10 Jan 2005 10:42:07 -0000 Received: from mailnull by ptb-spamcore02.plus.net with spamcore-l-b (Exim 4.32; FreeBSD) id 1CnwzS-0007Ka-49 for dave@picks.force9.co.uk; Mon, 10 Jan 2005 10:41:39 +0000 Received: from [192.168.67.3] (helo=ptb-mxcore03.plus.net) by ptb-spamcore02.plus.net with esmtp (Exim 4.32; FreeBSD) id 1CnwzS-0007KX-1Z for dave@picks.force9.co.uk; Mon, 10 Jan 2005 10:41:38 +0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore03.plus.net with esmtp (Exim) id 1Cnwzt-0000DK-HA for dave@picks.force9.co.uk; Mon, 10 Jan 2005 10:42:05 +0000 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Cnwx8-00074E-Cz for rs_out_1@blacksheep.org; Mon, 10 Jan 2005 10:39:14 +0000 Received: from [193.82.116.30] (helo=relay.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Cnwx7-000745-UO for rsgb_lf_group@blacksheep.org; Mon, 10 Jan 2005 10:39:13 +0000 Received: from smtp-out2.email.it ([80.247.70.7]) by relay.thorcom.net with esmtp (Exim 4.43) id 1Cnwx5-0004Jq-I3 for rsgb_lf_group@blacksheep.org; Mon, 10 Jan 2005 10:39:13 +0000 Received: by smtp-out2.email.it (Email.it, from userid 101) id 2FB891BC779; Mon, 10 Jan 2005 11:39:05 +0100 (CET) Received: from 1.118.222.41 (81-208-36-89.fastres.net [81.208.36.89])by smtp-out2.email.it (Email.it) with ESMTP id A1E801BC766for <rsgb_lf_group@blacksheep.org>; Mon, 10 Jan 2005 11:39:04 +0100 (CET) From: Claudio Pozzi <smtp01@email.it> To: rsgb_lf_group@blacksheep.org Date: Mon, 10 Jan 2005 11:45:45 +0100 User-Agent: KMail/1.5.3 References: <f6.4768d044.2f113828@aol.com> <Pine.OSF.4.56.0501081308220.10336@plato.ucs.mun.ca> In-Reply-To: <Pine.OSF.4.56.0501081308220.10336@plato.ucs.mun.ca> MIME-Version: 1.0 Content-Disposition: inline Message-Id: <200501101145.45777.smtp01@email.it> X-Copyrighted-Material: Please visit http://www.email.it/ita/privacy.html X-SPF-Result: relay.thorcom.net: 80.247.70.7 is neither permitted nor denied by domain of email.it X-Spam-Score: 0.5 (/) X-Spam-Report: autolearn=no,FROM_ENDS_IN_NUMS=0.516 Subject: Re: 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=0.9 required=5.0 tests=FROM_ENDS_IN_NUMS 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) 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