Return-Path: Received: (qmail 15564 invoked from network); 29 Sep 2001 12:44:48 -0000 Received: from unknown (HELO warrior-inbound.services.quay.plus.net) (212.159.14.227) by excalibur.plus.net with SMTP; 29 Sep 2001 12:44:48 -0000 Received: (qmail 27462 invoked from network); 29 Sep 2001 12:42:41 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by warrior with SMTP; 29 Sep 2001 12:42:41 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.16 #2) id 15nJFL-0000Um-00 for rsgb_lf_group-outgoing@blacksheep.org; Sat, 29 Sep 2001 13:29:31 +0100 Received: from mail4.svr.pol.co.uk ([195.92.193.211]) by post.thorcom.com with esmtp (Exim 3.16 #2) id 15nJFJ-0000Ug-00 for rsgb_lf_group@blacksheep.org; Sat, 29 Sep 2001 13:29:29 +0100 Received: from modem-67.brethil.dialup.pol.co.uk ([62.136.143.67] helo=g3aqc) by mail4.svr.pol.co.uk with smtp (Exim 3.13 #0) id 15nJBt-0003Zc-00 for rsgb_lf_group@blacksheep.org; Sat, 29 Sep 2001 13:25:57 +0100 Message-ID: <001a01c148e2$565e1660$438f883e@g3aqc> From: "Laurie Mayhead" To: rsgb_lf_group@blacksheep.org Subject: LF: Re.73KHz beacon Date: Sat, 29 Sep 2001 13:28:27 +0100 MIME-Version: 1.0 Content-Type: text/html; charset=windows-1252 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4133.2400 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: Content-transfer-encoding: 8bit
Hi David and all.
Peter G3LDO has leant me his Decca for a few weeks and
I have re-modified it for 73KHz.This mod. uses additional coils which slide into the existing ones so enabling fine adjustment and are of course easily removable so that the transmitter can be put back to 136 in a few minutes.
On 73KHz  I am getting 4A into my aerial (this requires 950W from the Decca),but it runs very cool.
The vert section of my Ant. is 14.5M high and Eznec gives me a Rres. of 0.018 on 73Khz. So at 4A I have 288mW Rad.Pwr. Field strength tests on 136 ( I hav'nt done any on 73 yet)  indicate a
3db loss. Assuming the same on 73 we have 144mW. However I am a bit confused here after reading Dicks comments on your
marathon tests,in which he mentions 2.62db gain for a monopole. If this is correct then the loss due to the environment is 5.62db not 3db. For the moment I am staying with 144mW which is a little under half of the power I was radiating earlier in the year on 136.,with reasonably good conditions I recon it should get across.
I hope the frequency is clear ,John did not seem to have any problems when he heard me earlier and Jon also recons its OK.
I will beacon again tonight although things appear very disturbed at the moment.
I will also be at Windsor on the Saturday and possibly the Sunday.
73s Laurie.