Return-Path: Received: (qmail 28588 invoked from network); 18 May 2000 19:35:24 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by grants.core.plus.net.uk with SMTP; 18 May 2000 19:35:24 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.02 #1) id 12sVdb-0007em-00 for rsgb_lf_group-outgoing@blacksheep.org; Thu, 18 May 2000 20:07:15 +0100 Received: from mail2.svr.pol.co.uk ([195.92.193.210]) by post.thorcom.com with esmtp (Exim 3.02 #1) id 12sVda-0007eh-00 for rsgb_lf_group@blacksheep.org; Thu, 18 May 2000 20:07:14 +0100 Received: from modem-56.edoras.dialup.pol.co.uk ([62.136.171.56] helo=lvm) by mail2.svr.pol.co.uk with smtp (Exim 3.13 #0) id 12sVdB-0003v2-00 for rsgb_lf_group@blacksheep.org; Thu, 18 May 2000 20:06:49 +0100 Message-ID: <000201bfc0fc$613ad380$38ab883e@lvm> From: "LAWRENCE MAYHEAD" To: "rsgb lf group" Subject: LF: Re. LF Recievers Date: Thu, 18 May 2000 20:07:07 +0100 MIME-Version: 1.0 Content-Type: text/html; charset=windows-1252 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 4.72.3110.5 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 Peter,
Further to your request for info/experience with recievers ,I have tried several.The station here includes a 4 section BP filter(PA0SE design)modified for 137.I hope that this keeps big signals out of the front ends of my Rxs although DCF39 138.8 is a bit too close for comfort! This filter is followed by about 12db of gain since my Loop and EWE type ants have very low outputs.An emitter follower OP stage enables me to drive 2 or 3 Rxs.The main reciever is an old Icom IC781 which has 2 excellent 250Hz CW filters.Gain is more than adequate on 137 and the spectrum display is useful for keeping an eye on band noise but too wide for anything else.The 250Hz filters are very good but sometimes too wide so I can switch in a NIR-12 DSP filter which can go down to about 60Hz.There is very little ringing with this filter but I would like to try the optimal design by PA0LQ. For monitoring the band and for QRS and DFCW I use a Racal 1792.This an excellent reciever and I agree with the comments by Andy G4JNT but although mine has 1Hz tuning steps,search tuning is very difficult,so I leave it set to a fixed frequency and use Spectrogram or Spectran to display the band or part of it as required.I have also tried an Icom IC756 PRO which has very excellant digital filtering the 50Hz setting is quite useable under all conditions even with high QRN.The display of filter width and pass band tuning is very useful but again the spectrum display is not too useful although somewhat narrower than the 781.The big problem with this Rx is that is a bit deaf on 137 about 18db down on the old 781.
I hope these notes are of intrest.73s Laurie..