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=1.7 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, FORGED_MUA_OUTLOOK 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 t0T1wiY2029375 for ; Thu, 29 Jan 2015 02:58:44 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1YGeGu-0006w8-ES for rs_out_1@blacksheep.org; Thu, 29 Jan 2015 01:51:52 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1YGeGu-0006vz-5V for rsgb_lf_group@blacksheep.org; Thu, 29 Jan 2015 01:51:52 +0000 Received: from rgout01.bt.lon5.cpcloud.co.uk ([65.20.0.178]) by relay1.thorcom.net with esmtp (Exim 4.85) (envelope-from ) id 1YGeGZ-0008O9-26 for rsgb_lf_group@blacksheep.org; Thu, 29 Jan 2015 01:51:51 +0000 X-OWM-Source-IP: 81.156.245.240(GB) X-OWM-Env-Sender: alan.melia@btinternet.com X-CTCH-RefID: str=0001.0A090204.54C99221.0086,ss=1,re=0.001,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0 X-Junkmail-Premium-Raw: score=38/50,refid=2.7.2:2015.1.20.154517:17:38.936,ip=81.156.245.240,rules=__HAS_MSGID, __SANE_MSGID, MSGID_32HEX_LC, INVALID_MSGID_NO_FQDN, __MSGID_32HEX, __HAS_FROM, __PHISH_FROM2, __FRAUD_WEBMAIL_FROM, __TO_MALFORMED_2, __TO_NO_NAME, __REFERENCES, __BOUNCE_CHALLENGE_SUBJ, __BOUNCE_NDR_SUBJ_EXEMPT, __SUBJ_ALPHA_END, __MIME_VERSION, __CT, __CT_TEXT_PLAIN, __CTE, __HAS_X_PRIORITY, __HAS_MSMAIL_PRI, __HAS_X_MAILER, USER_AGENT_OE, __OUTLOOK_MUA_1, __USER_AGENT_MS_GENERIC, __ANY_URI, __URI_NO_WWW, __URI_NO_PATH, __SUBJ_ALPHA_NEGATE, __FORWARDED_MSG, BODY_SIZE_1700_1799, BODYTEXTP_SIZE_3000_LESS, __MIME_TEXT_ONLY, RDNS_GENERIC_POOLED, __URI_NS, SXL_IP_DYNAMIC[240.245.156.81.fur], HTML_00_01, HTML_00_10, BODY_SIZE_5000_LESS, RDNS_SUSP_GENERIC, __PHISH_FROM, __OUTLOOK_MUA, __PHISH_SPEAR_STRUCTURE_1, RDNS_SUSP, BODY_SIZE_2000_LESS, __FRAUD_WEBMAIL, FORGED_MUA_OUTLOOK, BODY_SIZE_7000_LESS, REFERENCES X-CTCH-Spam: Unknown Received: from gnat (81.156.245.240) by rgout01.bt.lon5.cpcloud.co.uk (8.6.122.06) (authenticated as alan.melia@btinternet.com) id 54BD7093012D10DC for rsgb_lf_group@blacksheep.org; Thu, 29 Jan 2015 01:51:29 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=btinternet.com; s=btcpcloud; t=1422496291; bh=I7fCoLo8oOMde45d/e2mrwvTsm43sTYcZfVvchJlYb8=; h=Message-ID:From:To:References:Subject:Date:MIME-Version:X-Mailer; b=iVSUXExAT5/k4qQp9nvJeNgKGnqW6AXn/fOj9E9Hydia/4cN3g4YE8uop9FnH+Y2IGjrV1FDfW6XZ0KS2Dk99TniXeSLO40ZgQa6TNzyPAuaMhFfFQP9DSlEB1GS52btuLgK76f1Fqy1RxIFXB1sLHXAV4wunai6/VioziZmyBM= Message-ID: <63034551445741D196CDA19AFB8FC8B7@gnat> From: "Alan Melia" To: References: Date: Thu, 29 Jan 2015 01:51:24 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5931 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.6157 X-Scan-Signature: 66d07794ca19cd68f7d6cc289cd4ac18 Subject: LF: Re: RL aerial Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=response Content-Transfer-Encoding: 7bit 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: RO X-Status: X-Keywords: X-UID: 2183 Hi Joe the sloping top would reduce thr Rrad a little so <1ohm ....crank the Variac back upagain :-)) ----- Original Message ----- From: To: Sent: Thursday, January 29, 2015 1:09 AM Subject: LF: RL aerial > 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 > > > >