Return-Path: X-Spam-DCC: paranoid 1170; 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 t8TCluqb006314 for ; Tue, 29 Sep 2015 14:47:56 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1ZguHL-0000VN-PS for rs_out_1@blacksheep.org; Tue, 29 Sep 2015 13:45:07 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1ZguHL-0000VE-GV for rsgb_lf_group@blacksheep.org; Tue, 29 Sep 2015 13:45:07 +0100 Received: from rgout0306.bt.lon5.cpcloud.co.uk ([65.20.0.212]) by relay1.thorcom.net with esmtp (Exim 4.86) (envelope-from ) id 1ZguGI-000571-K6 for rsgb_lf_group@blacksheep.org; Tue, 29 Sep 2015 13:45:06 +0100 X-OWM-Source-IP: 81.155.177.128 (GB) X-OWM-Env-Sender: alan.melia@btinternet.com X-CTCH-RefID: str=0001.0A090201.560A8787.00EF,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0 X-Junkmail-Premium-Raw: score=38/50,refid=2.7.2:2015.9.9.110916:17:38.936,ip=81.155.177.128,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, __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, __CP_URI_IN_BODY, __STOCK_PHRASE_7, __SUBJ_ALPHA_NEGATE, __INT_PROD_TV, __URI_IN_BODY, __FORWARDED_MSG, BODY_SIZE_1700_1799, BODYTEXTP_SIZE_3000_LESS, __MIME_TEXT_ONLY, RDNS_GENERIC_POOLED, __URI_NS, SXL_IP_DYNAMIC[128.177.155.81.fur], HTML_00_01, HTML_00_10, BODY_SIZE_5000_LESS, RDNS_SUSP_GENERIC, __PHISH_FROM, __OUTLOOK_MUA, __PHISH_SPEAR_STRUCTURE_1, BODY_SIZE_2000_LESS, RDNS_SUSP, __FRAUD_WEBMAIL, FORGED_MUA_OUTLOOK, BODY_SIZE_7000_LESS, __SINGLE_URI_TEXT, REFERENCES, NO_URI_HTTPS, SINGLE_URI_IN_BODY X-CTCH-Spam: Unknown Received: from gnat (81.155.177.128) by rgout03.bt.lon5.cpcloud.co.uk (8.6.122.06) (authenticated as alan.melia@btinternet.com) id 55DD8A4A04084EFD for rsgb_lf_group@blacksheep.org; Tue, 29 Sep 2015 13:43:51 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=btinternet.com; s=btcpcloud; t=1443530642; bh=lnAAqd9tw2cNzbVeLSmafnaox8Mf4suS0cYoMUCPHaE=; h=Message-ID:From:To:References:Subject:Date:MIME-Version:X-Mailer; b=qsAOJXYHkITxiirMvT5KWerTvolh2AhCYaWRafsO3jeMe7o/Y9dNMeGojSLysdHUBq9eWORastKkm0tlrS/PR3RwRvZie28FIdXIrYf5TQvNyXyL6nxBgjbVPWv/xV3ueNDX5saxZ80AC7rmky1nQRnTIVc6yHD1chy5QVSvi+E= Message-ID: <303E79ED08714B6EA8827B2A47AB88A0@gnat> From: "Alan Melia" To: References: <453589076.20150929131349@chriswilson.tv> Date: Tue, 29 Sep 2015 13:43:52 +0100 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: 4b5b5ebe37a4c4f430f59bc35c1947b0 Subject: LF: Re: Active antennas on 136kHz, additional wire needed? Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original 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: O X-Status: X-Keywords: X-UID: 4203 Chris, It should not be necessary. The E-field probe couples to the incomming wavefront capacitively and extra wire adds little to this. The secret is the "size" of the segment of wavefront you intercept.....between the capacitive plate and the ground connection. Thus the higher you can mount it the bigger the signal you will get from it. E=heff*Fs The signal received on the plate is of course at very high impedance and the active bit is an impedance transformer converting the signal to drive 50ohm coax. The "voltage gain" is probably very close to one. Use the idling carrier of DCF39 on 138.83kHz as a test signal. this has a daytime field strength in the UK of approximately 1mV/m ...as measured several years ago by Dick Rollema PA0SE at an RSGB Convention. Alan G3NYK ----- Original Message ----- From: "Chris Wilson" To: Sent: Tuesday, September 29, 2015 1:13 PM Subject: LF: Active antennas on 136kHz, additional wire needed? > 29 September 2015 > > > A friend bought me an active RX antenna, a PA0RDT clone, from Ebay: > > http://www.ebay.co.uk/itm/111719689171?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT > > as a gift for sorting a car problem. It's built and working, but the > build notes suggest an additional wire on the PCB that acts as the > aerial may be needed. What are people's thoughts on adding say a 12 > inch wire poking out the PVC tube that it will be mounted high up > outside > in? Necessary or not? Just use the PCB board antenna? Thanks. > > > > -- > > > Best regards, > Chris mailto:chris@chriswilson.tv > >