Return-Path: Received: (qmail 81149 invoked from network); 16 Sep 2004 15:27:47 -0000 Received: from unknown (HELO ptb-spamcore01.plus.net) (192.168.71.1) by ptb-mailstore01.plus.net with SMTP; 16 Sep 2004 15:27:47 -0000 Received: from mailnull by ptb-spamcore01.plus.net with spamcore-l-b (Exim 4.32; FreeBSD) id 1C7yJB-0007cq-D7 for dave@picks.force9.co.uk; Thu, 16 Sep 2004 16:36:30 +0100 Received: from [192.168.67.2] (helo=ptb-mxcore02.plus.net) by ptb-spamcore01.plus.net with esmtp (Exim 4.32; FreeBSD) id 1C7yJB-0007cn-Ad for dave@picks.force9.co.uk; Thu, 16 Sep 2004 16:36:29 +0100 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore02.plus.net with esmtp (Exim) id 1C7yAk-000EGQ-JR for dave@picks.force9.co.uk; Thu, 16 Sep 2004 15:27:46 +0000 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1C7y9h-0007Lp-5a for rs_out_1@blacksheep.org; Thu, 16 Sep 2004 16:26:41 +0100 Received: from [193.82.116.30] (helo=relay.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1C7y9g-0007Lg-Po for rsgb_lf_group@blacksheep.org; Thu, 16 Sep 2004 16:26:40 +0100 Received: from cas-mta4-fe.casema.nl ([83.80.1.32] helo=mta.casema.nl) by relay.thorcom.net with esmtp (Exim 4.41) id 1C7y9d-0008Gv-8O for rsgb_lf_group@blacksheep.org; Thu, 16 Sep 2004 16:26:40 +0100 Received: from w8k3f0.casema.nl (53556B6D.cable.casema.nl [83.85.107.109]) by cas-mta4.mgmt.casema.nl (iPlanet Messaging Server 5.2 HotFix 1.21 (built Sep 8 2003)) with ESMTP id <0I450053M487LZ@cas-mta4.mgmt.casema.nl> for rsgb_lf_group@blacksheep.org; Thu, 16 Sep 2004 17:26:32 +0200 (CEST) Date: Thu, 16 Sep 2004 17:33:07 +0200 From: Dick Rollema X-Sender: dickrollema@casema.nl@mail.casema.nl (Unverified) To: LF-Group Message-id: <6.1.0.6.2.20040916171458.02f86360@mail.casema.nl> MIME-version: 1.0 X-Mailer: QUALCOMM Windows Eudora Version 6.1.0.6 X-SPF-Result: relay.thorcom.net: 83.80.1.32 is neither permitted nor denied by domain of casema.nl X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=no,HTML_MESSAGE=0.001 Subject: LF: SL6440 Content-type: text/html; charset=windows-1252 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=HTML_MESSAGE 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) Content-transfer-encoding: 8bit To All from PA0SE

Claudio, IK2PII wrote:

SL6440 is a good mixer, low IMD but high noise. For HF receiver it
require a preamplifier also for 7 MHz band.

I don't agree. I my own homemade transceiver (see RadCom, Technical Topics, October 2004) I use the SL6440 as the first and second mixer.
Between the antenna and the first mixer is a fixed tuned Cohn bandpass filter with four tuned circuits for each of the bands 10 - 160 m (9 in total). The insertion loss of these filters depends on the band selected and is 2.2dB on 10m.
I find that with a good antenna a preamplifier is only required on 10 and 12m in order to make the noise from outside override the receiver noise.

73, Dick, PA0SE