Return-Path: Received: (qmail 74752 invoked from network); 15 Aug 2004 15:06:49 -0000 Received: from unknown (HELO ptb-spamcore02.plus.net) (192.168.71.3) by ptb-mailstore01.plus.net with SMTP; 15 Aug 2004 15:06:49 -0000 Received: from mailnull by ptb-spamcore02.plus.net with spamcore-l-b (Exim 4.32; FreeBSD) id 1BwMfG-000MeI-LX for dave@picks.force9.co.uk; Sun, 15 Aug 2004 16:11:19 +0100 Received: from [192.168.67.1] (helo=ptb-mxcore01.plus.net) by ptb-spamcore02.plus.net with esmtp (Exim 4.32; FreeBSD) id 1BwMfG-000MeF-Hv for dave@picks.force9.co.uk; Sun, 15 Aug 2004 16:11:18 +0100 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore01.plus.net with esmtp (Exim 4.30; FreeBSD) id 1BwMav-0000N0-15 for dave@picks.force9.co.uk; Sun, 15 Aug 2004 15:06:49 +0000 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1BwMaN-00088T-3a for rs_out_1@blacksheep.org; Sun, 15 Aug 2004 16:06:15 +0100 Received: from [193.82.116.30] (helo=relay.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1BwMaM-00088K-Ly for rsgb_lf_group@blacksheep.org; Sun, 15 Aug 2004 16:06:14 +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 1BwMaJ-0006u5-0B for rsgb_lf_group@blacksheep.org; Sun, 15 Aug 2004 16:06:14 +0100 Received: from w8k3f0 (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 SMTP id <0I2H00FHBTY5JI@cas-mta4.mgmt.casema.nl> for rsgb_lf_group@blacksheep.org; Sun, 15 Aug 2004 17:06:05 +0200 (CEST) Date: Sun, 15 Aug 2004 17:10:18 +0200 From: Dick Rollema To: rsgb_lf_group@blacksheep.org Message-id: <002601c482da$14935da0$6d6b5553@w8k3f0> MIME-version: 1.0 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1441 X-Mailer: Microsoft Outlook Express 6.00.2800.1437 X-Priority: 3 X-MSMail-priority: Normal References: <001901c482be$69d9e020$68878751@jgtdiynm> X-SPF-Result: relay.thorcom.net: 83.80.1.32 is neither permitted nor denied by domain of casema.nl X-Spam-Score: 0.5 (/) X-Spam-Report: autolearn=no,HTML_20_30=0.474,HTML_MESSAGE=0.001 Subject: LF: Re: 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=0.5 required=5.0 tests=HTML_20_30,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

James, M0BMU wrote:

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.

Another possibility is to use only the RF stages to improve the front-end selectivity. Pick off the signal at the input of the mixer.

I do so to improve the large signal behaviour of my W & G SPM-12 selective level meter. The meter has no input selectivity at all, the signal is fed directly to the mixer.

I use the front-end of my Teletron LWF45 receiver (5 tuned and ganged circuits) as a preselector before the SPM-12 with good results.

73, Dick, PA0SE