Return-Path: X-Spam-DCC: paranoid 1290; Body=2 Fuz1=2 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-1.4 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, NO_REAL_NAME autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id t0T1GRgn029330 for ; Thu, 29 Jan 2015 02:16:27 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1YGdbf-0006hF-Co for rs_out_1@blacksheep.org; Thu, 29 Jan 2015 01:09:15 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1YGdbe-0006h6-Rn for rsgb_lf_group@blacksheep.org; Thu, 29 Jan 2015 01:09:14 +0000 Received: from nina.ucs.mun.ca ([134.153.232.76]) by relay1.thorcom.net with esmtps (TLSv1:DHE-RSA-AES256-SHA:256) (Exim 4.85) (envelope-from ) id 1YGdbc-0008Go-Tg for rsgb_lf_group@blacksheep.org; Thu, 29 Jan 2015 01:09:13 +0000 Received: from plato.ucs.mun.ca (plato.ucs.mun.ca [134.153.232.153]) by nina.ucs.mun.ca (8.13.1/8.13.1) with ESMTP id t0T199Xr026115 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Wed, 28 Jan 2015 21:39:09 -0330 Date: Wed, 28 Jan 2015 21:39:09 -0330 (NST) From: jcraig@mun.ca X-X-Sender: jcraig@plato.ucs.mun.ca To: rsgb_lf_group@blacksheep.org In-Reply-To: Message-ID: References: MIME-Version: 1.0 X-Scan-Signature: 6ffbd2c9950b634d6cc91f9565b01a8b Subject: LF: RL aerial Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-Scanned-By: MIMEDefang 2.56 on 10.1.3.10 Status: O X-Status: X-Keywords: X-UID: 2181 Dear Group, Rik and Jean Pierre were asking about the new aerial here. Jean-Pierre sent yesterday a series of captures from 2208-0730 showing much variation in the signal levels on 477.7 kHz. They were quite strong between 0330 and 0500 though there were other peaks and complete fades during the night. Many thanks Jean-Pierre. Here are the details about the "Rotated L" now on the air on 477.7 kHz. Comments and critiques are most welcome. The current was read with a clamp-on ammeter which was then calibrated by measuring current through a 50 ohm load. The wattmeter power was 70 watts but the scope was showing 200V p/p which is 100 watts. Perhaps the wattmeter is reading low. It had a nasty accident with a Decca, was repaired but not properly recalibrated. Assuming the scope is the more accurate, the current was I=P/V=100/71=1.4 A. Scaling the aerial current accordingly yields 1.6 amps. The RL extends from the feedpoint up 27 metres and slopes down to 12 metres over a 100m span. The mean height is about 18 metres. It is fed with ~50 uH of tuning; no R matching was needed. A 30m vertical has Rrad~1 ohm on 630 metres. The ON7YD page gives an expression for Rrad for a horizontal top load, but the RL is sloping this will reduce Rrad. Let's guess that it's 2 ohms So... ERP=I^2R= 2.6 R or about 5 watts. I'd best crank the variac down a few notches to keep it legal! 73 Joe VO1NA