Return-Path: Received: (qmail 19488 invoked from network); 1 Jul 2003 15:42:43 -0000 Content-Transfer-Encoding: 8bit Received: from netmail02.services.quay.plus.net (212.159.14.221) by mailstore with SMTP; 1 Jul 2003 15:42:43 -0000 Received: (qmail 20281 invoked by uid 10001); 1 Jul 2003 15:42:43 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: from post.thorcom.com (193.82.116.70) by netmail02.services.quay.plus.net with SMTP; 1 Jul 2003 15:42:43 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-SQ: A Received: from majordom by post.thorcom.com with local (Exim 4.14) id 19XNGS-0002A0-1o for rsgb_lf_group-outgoing@blacksheep.org; Tue, 01 Jul 2003 16:41:52 +0100 Received: from [147.197.200.9] (helo=hestia.herts.ac.uk) by post.thorcom.com with esmtp (Exim 4.14) id 19XNGK-00029r-H5 for rsgb_lf_group@blacksheep.org; Tue, 01 Jul 2003 16:41:44 +0100 Received: from gemini ([147.197.200.44] helo=gemini.herts.ac.uk) by hestia.herts.ac.uk with esmtp (Exim 3.22 #1) id 19XNGF-000204-00 for rsgb_lf_group@blacksheep.org; Tue, 01 Jul 2003 16:41:39 +0100 Received: from [147.197.232.252] (helo=rsch-15.herts.ac.uk) by gemini.herts.ac.uk with esmtp (Exim 3.33 #1) id 19XNGD-0005tB-00 for rsgb_lf_group@blacksheep.org; Tue, 01 Jul 2003 16:41:37 +0100 Message-ID: <5.1.0.14.0.20030701154317.025a9ab0@gemini.herts.ac.uk> X-Sender: mj9ar@gemini.herts.ac.uk X-Mailer: QUALCOMM Windows Eudora Version 5.1 Date: Tue, 01 Jul 2003 16:41:33 +0100 To: rsgb_lf_group@blacksheep.org From: "James Moritz" In-reply-to: <01C33FD7.0DC9BFB0.g4jnt@thersgb.net> MIME-Version: 1.0 X-MailScanner: No Virus detected Subject: RE: LF: SAQ nil Content-Type: text/plain; charset=us-ascii; format=flowed X-Spam-Status: No, hits=-1.0 required=5.0tests=EMAIL_ATTRIBUTION,IN_REP_TOversion=2.55 X-Spam-Checker-Version: SpamAssassin 2.55 (1.174.2.19-2003-05-19-exp) X-SA-Exim-Scanned: Yes Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rsgb_lf_group-outgoing@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false Dear Andy, LF group, At 13:45 01/07/2003 +0100, you wrote: >RU Sure ??? > >The RA1792 (the following model from the 1772 perhaps) displays the actual >frequency at the middle of the filter passband, then generates an audio Yes - well, it certainly is on mine anyway... The 1772 predates microcontrollers, and is completely different in design from the 1792, although some parts have clearly been cribbed for the later design. Racal have opted for a fixed BFO frequency in all modes centered at the 1.4MHz IF centre frequency, with separate USB and LSB filters for SSB/ISB. CW reception is actually in USB mode, with narrower filters with passband centres offset by 1kHz from the BFO frequency... whatever mode you select, the displayed frequency is the one at which the input signal will be zero-beat with the BFO, and so outside the filter passband with narrow bandwidths. The display board has buckets of TTL and stuff - I expect the designers thought correcting the display for different modes was too much trouble. But so you are not stuck with a fixed 1kHz audio tone, they provided a rather drifty variable analogue BFO as well. A little idiosyncratic, you might say! Cheers, Jim Moritz 73 de M0BMU