Return-Path: Received: (qmail 21047 invoked from network); 19 Apr 1999 07:04:20 +0100 Received: from magnus.plus.net.uk (HELO magnus.force9.net) (195.166.128.27) by guiness.force9.net with SMTP; 19 Apr 1999 07:04:20 +0100 Received: (qmail 3797 invoked from network); 19 Apr 1999 06:04:39 -0000 Received: from post.thorcom.com (194.75.130.70) by magnus.plus.net.uk with SMTP; 19 Apr 1999 06:04:39 -0000 Received: from troy.blacksheep.org ([194.75.183.50] ident=root) by post.thorcom.com with esmtp (Exim 2.04 #3) id 10Z76y-0004FT-01; Mon, 19 Apr 1999 07:00:52 +0100 Received: (from root@localhost) by troy.blacksheep.org (8.6.12/8.6.12) id GAA29218 for rsgb_lf_group-outgoing; Mon, 19 Apr 1999 06:00:32 GMT X-Priority: 3 X-MSMail-Priority: Normal Received: from post.thorcom.com (root@post.unica.co.uk [194.75.183.70]) by troy.blacksheep.org (8.6.12/8.6.12) with ESMTP id GAA29214 for ; Mon, 19 Apr 1999 06:00:30 GMT Received: from ns.cro.cz ([193.179.196.2] ident=qmailr) by post.thorcom.com with smtp (Exim 2.04 #3) id 10Z76U-0004FM-00 for rsgb_lf_group@blacksheep.org; Mon, 19 Apr 1999 07:00:22 +0100 Received: (qmail 29529 invoked from network); 19 Apr 1999 06:00:17 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from fw.cro.cz (HELO ns-int.cro.cz) (193.179.197.2) by ns.cro.cz with SMTP; 19 Apr 1999 06:00:17 -0000 Received: from radiohk.hk.cro.cz (ns.hk.cro.cz [172.27.1.2]) by ns-int.cro.cz (8.8.5/8.8.5) with ESMTP id IAA07715 for ; Mon, 19 Apr 1999 08:00:16 +0200 (MET DST) Received: from pc033hk.hk.cro.cz ([172.27.1.33]) by radiohk.hk.cro.cz (8.9.1/8.9.1) with SMTP id IAA00856 for ; Mon, 19 Apr 1999 08:00:12 +0200 (MET DST) Received: by pc033hk.hk.cro.cz with Microsoft Mail id <01BE8A3A.A6385B00@pc033hk.hk.cro.cz>; Mon, 19 Apr 1999 08:00:11 +-200 Message-ID: <01BE8A3A.A6385B00@pc033hk.hk.cro.cz> From: "Petr Maly" To: "'137 kHz'" Subject: LF: Q-ed loop Date: Mon, 19 Apr 1999 08:00:10 +-200 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 8bit Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org Hi LowFers. Too lazy to make quality narrow input filter I tried another thing. I made a loop ant of a shape of square, 65cm by 65cm. Size mainly limited by my wife's tolerance. There are two windings on it. Main is 50 turns and the latter is separate 5 turns. Used wire is insulated copper wire diameter 0.3 mm only . The main one is tuned to resonance by varible capacitor abt 500 pF. Hot end is fed to gate of BF245. In collector (drain) there is the the latter winding in series with trimmer 2200 ohm. The 'polarity' of this secondary winding must tried to find positive feedback. By the trimmer the feedback can be easily adjusted so that you can find a point where oscillation begins. It you set feedback close to this point (not necessary to be very close) the ant has following behaviour. It tunes very sharply. It has to be retuned even within 136 kHz band. When it is carefully tuned to a certain fq (136 kHz) the fq 3 kHz distant (139 kHz) seems to have attenuation about 15 dB! I was surprised that the band is actually empty, full of smooth ground noise, which is different from what I experienced before on this band. Also, galloping horses can be clearly heard on 100 kHz. To tell the whole story I live in a block of flats so that there is a lot of TV sets and other appliances in vicinity. I tried to listen several times during this wekend but I have not heard any ham-looking signals. My QTH is Hradec Kralove which is about 100 km east from capital Prague. Locator is JO70WE. Who is closest to me? Is he willing to make a beacon for me for few minutes? Ones I saw 137 kHz in DX-Cluster too, but not this weekend. Are there any prefered times/fqs to try to listen on the band? 73! Petr, OK1FIG