Return-Path: Received: (qmail 1642 invoked from network); 15 May 2000 15:58:08 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by teachers.core.plus.net.uk with SMTP; 15 May 2000 15:58:08 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.02 #1) id 12rN9Z-0006RM-00 for rsgb_lf_group-outgoing@blacksheep.org; Mon, 15 May 2000 16:51:33 +0100 Received: from kerberos.telecom.cz ([194.228.2.35] helo=mail.core.telecom.cz) by post.thorcom.com with esmtp (Exim 3.02 #1) id 12rN9U-0006RE-00 for rsgb_lf_group@blacksheep.org; Mon, 15 May 2000 16:51:28 +0100 Received: from dell1.cz.gmc.net ([194.228.225.18]) by mail.core.telecom.cz (8.9.3/8.9.3) with ESMTP id RAA14581 for ; Mon, 15 May 2000 17:51:02 +0200 Received: from p (p.maly.cz.gmc.net [192.168.1.35]) by dell1.cz.gmc.net with SMTP (Microsoft Exchange Internet Mail Service Version 5.5.2650.21) id KSG6KBV2; Mon, 15 May 2000 17:52:02 +0200 Message-ID: <018201bfbe85$83b0e7c0$2301a8c0@maly.cz.gmc.net> From: "Petr Maly" To: rsgb_lf_group@blacksheep.org References: <09e401bfbc0e$5e55ab60$2301a8c0@maly.cz.gmc.net> <004c01bfbe61$552ed160$0600a8c0@MARC> Subject: LF: Re: Re: Optimal width for LF? Date: Mon, 15 May 2000 17:52:03 +0200 MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-2; format=flowed Content-Transfer-Encoding: 8bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.00.2014.211 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: I mix 10 MHz VXO with 8863 kHz XO. Stability looks sufficient, all this gear will be placed in closed robust alluminium box which will be surrounded by polystyrene casing to provide temperature isolation. I wanted to have no tuning step to be able to use extremely narrow filters. 73, Petr, OK1FIG ----- Original Message ----- From: mv tsi To: Sent: Monday, May 15, 2000 1:32 PM Subject: LF: Re: Optimal width for LF? > Hello petr, > I am interested to make a receiver. > But what technology can you use for hight stability frequency? > VFO,DDS? > My first receiver used a 3Mhz VFO and a IF at 11Mhz. > (I had a 137Khz 14 Mhz converter). > I had some probleme to have a narrow band pass with 5 cristals (800Hz). > For reduct audio band pass I used a MF10. > But with this receiver I couldn't survey a frequency during more hours. > The VFO stability had no perfect. > 73 marc. > ----- Original Message ----- > From: Petr Maly > To: 136 group > Sent: Friday, May 12, 2000 2:34 PM > Subject: LF: Optimal width for LF? > > > > Hello all > > I am just designing a new RX for 136 kHz band. It will have IF on 1 MHz > with > > high quality x-tal filter with bandwidth 200 Hz. The main selectivity will > > by obtained on AF with passive filter with coils on pot cores. Till now I > > used similar filter with bandwidth about 50 Hz and it seems to be still > too > > wide for LF. I was about to make it new with 15 Hz width. Somebody here > > mentioned 1 Hz wide filter which seems to me to be too narrow. At least, > the > > filter cannot be narrower than obtainable osc stability. Can we make a > > little questionnaire here? What bandwidth do you use and what is the > > experience? > > > > 73, Petr, OK1FIG > > > > > > > > > > > > > > > > >