Return-Path: Received: (qmail 22959 invoked from network); 15 Apr 2000 18:07:55 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by teachers.core.plus.net.uk with SMTP; 15 Apr 2000 18:07:55 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.02 #1) id 12gWkt-0004my-00 for rsgb_lf_group-outgoing@blacksheep.org; Sat, 15 Apr 2000 18:53:15 +0100 X-Priority: 3 X-MSMail-Priority: Normal Received: from ds-img-7.compuserve.com ([149.174.206.153] helo=spdmbaaa.compuserve.com) by post.thorcom.com with esmtp (Exim 3.02 #1) id 12gWkq-0004mt-00 for rsgb_lf_group@blacksheep.org; Sat, 15 Apr 2000 18:53:12 +0100 Received: (from mailgate@localhost) by spdmbaaa.compuserve.com (8.9.3/8.9.3/SUN-1.9) id NAA00795 for rsgb_lf_group@blacksheep.org; Sat, 15 Apr 2000 13:52:28 -0400 (EDT) X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Date: Sat, 15 Apr 2000 13:52:02 -0400 From: "'Geri' Kinzel, DK8KW" Subject: LF: Info selective voltmeter WG TFH-2 To: rsgb_lf_group@blacksheep.org Message-ID: <200004151352_MC2-A157-C9D@compuserve.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Disposition: inline Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: Hello Renato, >Hi! >I have a selective voltmeter Wandel & Goltermann TFH-2. >I tried to listen our 136 khz qso but I was not able to listen (i have a multiturn loop homemade, 1 m. diameter, tuned via a variable capacitor. The signal >is amplified by a cascode bi-Fet) >I think my selective voltmeter is too little sensitive (it is able to measure -40 to + 40 dB). >I think it is possible to modify it! >Have you modified it? >Can you help me? >or must I put it in in the garbage :-(((( ? >Thanks and best regards >Renato IK2WYS you are right, - 40 dB, is not sensitive enough (if it is -40 dBm, this is equivalent to about 2 mV sensitivity, what you need would be at least about -110 dBm. You might be able to increase the sensitivity with a pre-amplifier. However, don't through it away, those selective voltmeter do an excellent job to measure the near-field of a transmitting station, and for that purpose the sensitivity should be ok! Anyhow, don't through it away, whatever you do ... those old instruments have a lot of components that might be usable for LF applications ... Vy 73 Geri, DK8KW (W1KW)