Return-Path: Received: (qmail 5216 invoked from network); 23 Jan 2000 17:08:07 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by grants.core.plus.net.uk with SMTP; 23 Jan 2000 17:08:07 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.02 #1) id 12CQPl-0006AY-00 for rsgb_lf_group-outgoing@blacksheep.org; Sun, 23 Jan 2000 17:03:01 +0000 Received: from mail04.hostcenter.com ([195.186.64.57]) by post.thorcom.com with smtp (Exim 3.02 #1) id 12CQPj-0006AT-00 for rsgb_lf_group@blacksheep.org; Sun, 23 Jan 2000 17:02:59 +0000 Received: from www303.hostcenter.com (195.186.64.84) by mail04.hostcenter.com (RS ver 1.0.53) with SMTP id 01298892 for ; Sun, 23 Jan 2000 18:02:30 +0100 (MET) Message-ID: <388B3427.CFB567B6@phonakcom.ch> X-Priority: 3 X-MSMail-Priority: Normal Date: Sun, 23 Jan 2000 18:02:31 +0100 From: =?iso-8859-1?Q?Toni_B=E4rtschi?= Organization: Phonak Communications AG X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-Mailer: Mozilla 4.6 [de] (Win98; I) X-Accept-Language: de,en-US,en-GB,fr-FR MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org Subject: Re: LF: Resonance and Impedance change in the winter season References: <38856E64.9E096059@phonakcom.ch> <12CAtp-0vGqXZC@fwd05.sul.t-online.de> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 8bit X-Loop-Detect: 1 Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: Here I'm using now an LF match box in the shack, so it's no longer necessary to go outside for fine tuning. It's a PI-configuration with parallel C's at the in and output, they can be switched in 5nF steps up to 50nF. The serial Inductor is a 28uH roller type and I can switch-in additional L up to 150uH if needed. Now I can leave my base coil in a standard configuration and adjust to a 1:1 SWR (my TX likes it) with the PI-filter. Very nice, especially at night, when it is snowing outside, hi. An interesting detail: The russian door-knob condensers I bought in Friedrichshafen were all dead, but I was lucky and found a box of large american mica condensers I had put away some 20 years ago - still the better stuff, hi. 73 de Toni, HB2ASB Hans-Joachim Brandt schrieb: > > Toni Baertschi schrieb: > > >From HB9ASB, JN36pt > > > > > PS. Actually it is very cold here and my antenna de-tunes from hour to > > hour as the soil is freezing deeper and deeper. Not only the resonance > > goes higher, the impedance is also changing and it is difficult to > > follow this developement with the existing matching circuit. > > Now, during winter time I can make the same observations. Before I have just > experienced small changes in resonance, but now, in the cold, not only resonance > changes considerably but also VSWR increases to S = 2 at optimum tune (I am > using a 50 ohms feeder cable between PA and LF antenna). Therefore I also have > to revise my fine tuning and matching circuitry to cope with these effects. > > 73 Ha-Jo, DJ1ZB > > > > > > > > > > > > > > > > > > >