Return-Path: Received: (qmail 27722 invoked from network); 30 May 2001 09:45:21 -0000 Received: from unknown (HELO murphys-inbound.servers.plus.net) (212.159.14.225) by excalibur.plus.net with SMTP; 30 May 2001 09:45:21 -0000 Received: (qmail 13612 invoked from network); 30 May 2001 09:44:48 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by murphys with SMTP; 30 May 2001 09:44:48 -0000 X-Priority: 3 Received: from majordom by post.thorcom.com with local (Exim 3.16 #2) id 1552RH-0005Nj-00 for rsgb_lf_group-outgoing@blacksheep.org; Wed, 30 May 2001 10:38:51 +0100 X-MSMail-Priority: Normal Received: from hestia.herts.ac.uk ([147.197.200.9]) by post.thorcom.com with esmtp (Exim 3.16 #2) id 1552RD-0005Ne-00 for rsgb_lf_group@blacksheep.org; Wed, 30 May 2001 10:38:47 +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 1552Qe-0000gv-00 for rsgb_lf_group@blacksheep.org; Wed, 30 May 2001 10:38:12 +0100 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from [147.197.130.252] (helo=mj9ar) by gemini.herts.ac.uk with smtp (Exim 3.22 #2) id 1552Qd-0001UN-00 for rsgb_lf_group@blacksheep.org; Wed, 30 May 2001 10:38:11 +0100 From: "James Moritz" Organization: University of Hertfordshire To: rsgb_lf_group@blacksheep.org Date: Wed, 30 May 2001 10:39:03 +0000 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 8bit Subject: LF: RA1792 audio calibration X-Mailer: Pegasus Mail for Win32 (v3.11) Message-ID: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: Dear LF group, If you have an RA1792 RX, and require and accurate audio frequency (for calibrating a sound card for "Wolf" reception for instance), you can get one very easily by tuning the RX to 0Hz in CW mode. This makes the LO equal to the IF frequency, and some signal leaks through the mixer into the IF, where it is demodulated as a CW tone. The audio frequency output is then equal to the BFO offset, which can be set in 10Hz steps from 0 to 8kHz, as I recall. The frequency accuracy will be that of the internal reference, ie. 0.1ppm if it has been calibrated fairly recently. This might well work in other receivers with synthesised BFOs which can be tuned to zero too. Cheers, Jim Moritz 73 de M0BMU