Return-Path: Received: (qmail 59023 invoked from network); 15 Aug 2004 11:54:12 -0000 Received: from unknown (HELO ptb-spamcore01.plus.net) (192.168.71.1) by ptb-mailstore01.plus.net with SMTP; 15 Aug 2004 11:54:12 -0000 Received: from mailnull by ptb-spamcore01.plus.net with spamcore-l-b (Exim 4.32; FreeBSD) id 1BwJeN-000DXD-1y for dave@picks.force9.co.uk; Sun, 15 Aug 2004 12:58:11 +0100 Received: from [192.168.67.2] (helo=ptb-mxcore02.plus.net) by ptb-spamcore01.plus.net with esmtp (Exim 4.32; FreeBSD) id 1BwJeM-000DXA-VT for dave@picks.force9.co.uk; Sun, 15 Aug 2004 12:58:10 +0100 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore02.plus.net with esmtp (Exim) id 1BwJaV-000BxE-7F for dave@picks.force9.co.uk; Sun, 15 Aug 2004 11:54:11 +0000 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1BwJZm-0007bJ-6E for rs_out_1@blacksheep.org; Sun, 15 Aug 2004 12:53:26 +0100 Received: from [193.82.116.30] (helo=relay.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1BwJZl-0007bA-Or for rsgb_lf_group@blacksheep.org; Sun, 15 Aug 2004 12:53:25 +0100 Received: from smtp811.mail.ukl.yahoo.com ([217.12.12.201]) by relay.thorcom.net with smtp (Exim 4.41) id 1BwJZi-0006Aw-4K for rsgb_lf_group@blacksheep.org; Sun, 15 Aug 2004 12:53:25 +0100 Received: from unknown (HELO jgtdiynm) (james.moritz@81.135.135.104 with login) by smtp811.mail.ukl.yahoo.com with SMTP; 15 Aug 2004 11:53:15 -0000 Message-ID: <001901c482be$69d9e020$68878751@jgtdiynm> From: "James Moritz" To: rsgb_lf_group@blacksheep.org Date: Sun, 15 Aug 2004 12:52:22 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.00.2615.200 X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2615.200 X-SPF-Result: relay.thorcom.net: 217.12.12.201 is neither permitted nor denied by domain of btopenworld.com X-Spam-Score: 0.1 (/) X-Spam-Report: autolearn=no,HTML_MESSAGE=0.001,RCVD_IN_SORBS=0.1 Subject: LF: Re: AR88LF IF output 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

Dear Bryan, LF Group,

Before hauling the AR88LF back to the shed, I tried using it as a tunable front end for another receiver tuned to 735kHz, as was suggested last week. I found a good place to tap off the IF signal was at the cathode of the first IF amplifier valve (V5 - 6SG7). On my unit this has a 100ohm un-bypassed cathode resistor between pin 3 and ground. Signal was taken from pin 3 to the second RX input through a 0.1uF DC blocking capacitor. This gave a satisfactory signal level for both my IC718 HF rig (which has somewhat reduced sensitivity at 735kHz) and RA1792 receiver. Obviously, selectivity was greatly improved, and sensitivity was good, as before. The AR88LF was operated with BFO and AGC switched off, and the selectivity switch in position 3 or 4. Having the second receiver connected did not seem to particularly alter the behaviour of the AR88 used by itself. The main drawback of this combination as a 136kHz receiver is the relatively poor frequency stability compared with a modern RX - but this would not be an issue for aural CW reception.

Can't help with Jane Russell, though ...

Cheers, Jim Moritz

73 de M0BMU