Return-Path: Received: (qmail 13172 invoked from network); 14 Mar 2003 11:11:22 -0000 Received: from netmail01.services.quay.plus.net (212.159.14.219) by mailstore with SMTP; 14 Mar 2003 11:11:22 -0000 Received: (qmail 28840 invoked by uid 10001); 14 Mar 2003 11:11:22 -0000 Received: from post.thorcom.com (193.82.116.70) by netmail01.services.quay.plus.net with SMTP; 14 Mar 2003 11:11:21 -0000 X-SQ: A Received: from majordom by post.thorcom.com with local (Exim 4.12) id 18tn5B-0004g8-00 for rsgb_lf_group-outgoing@blacksheep.org; Fri, 14 Mar 2003 11:10:37 +0000 Received: from [212.135.6.11] (helo=smarthost1.mail.uk.easynet.net) by post.thorcom.com with esmtp (Exim 4.12) id 18tn56-0004fz-00 for rsgb_lf_group@blacksheep.org; Fri, 14 Mar 2003 11:10:32 +0000 Received: from tnt-13-199.easynet.co.uk ([212.134.22.199] helo=erica) by smarthost1.mail.uk.easynet.net with smtp (Exim 4.10) id 18tn55-0002MW-00 for rsgb_lf_group@blacksheep.org; Fri, 14 Mar 2003 11:10:31 +0000 Message-ID: <001b01c2ea1a$ec6fe2c0$c71686d4@erica> From: "g3ldo" To: rsgb_lf_group@blacksheep.org References: <3E4BC23500033F62@mk-cpfrontend-4.mail.uk.tiscali.com> Date: Fri, 14 Mar 2003 11:11:16 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4522.1200 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Subject: LF: Rising damp Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Status: No, hits=-6.6 required=5.0tests=REFERENCESversion=2.50 X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) X-SA-Exim-Scanned: Yes Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rsgb_lf_group-outgoing@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false On Monday I had a visit from Laurence, KL1X. He was on his way from Surrey to Exeter and by the time he got here it was dusk. I showed him the garden shed transmitter shack and fired up the transmitter. I explained that the antenna current was behaving strangely lately, starting off rather low then building up. Laurence noticed that, in the half light, there was sparking occurring, in several places, inside the plastic covering of the 4mm Litz wire coil windings. We concluded that there must be damp inside the litz wire that had to be 'cooked' out before full power could be achieved. Building up a head of steam so to speak! Laurence remarked that he was aware of the problem in commercial LF set-ups and that this had been cured by arranging loading coils to be surrounded by an atmosphere of dry air. The Decca loading coil buildings had extensive electrical heating as I recall. Over the last few days I have cooked the loading coil by placing against radiator in the house. In the last couple of days the weather has become dry with a cold drying northerly wind. This morning, before taking the antenna down, I fired up the transmitter and the current meter hit 9.2Amps! The Decca transmitter 6amp current meter was endstop. I quickly switched off and tried different taps on the matching transformer. The antenna system seems to have a total resistance of about 20 or 25ohms at the moment and the tuning is very twitchy - the slightest movement of the antenna in the wind causes large variations of antenna current. I am not sure what is going on. I can only conclude that it is a combination of a dry loading coil and dry weather condition and a high tide. I had also cut down a lot of Ivy that covered a near dead tree about 3m from the loading coil. Or it might be the KL1X effect! Regards, Peter, G3LDO e-mail Web