Return-Path: Received: from rly-mc02.mx.aol.com (rly-mc02.mail.aol.com [172.21.164.86]) by air-mc01.mail.aol.com (v126.13) with ESMTP id MAILINMC012-d5b4b16ad2d32b; Wed, 02 Dec 2009 13:09:06 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-mc02.mx.aol.com (v125.7) with ESMTP id MAILRELAYINMC023-d5b4b16ad2d32b; Wed, 02 Dec 2009 13:08:47 -0500 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NFtcC-0006WY-9A for rs_out_1@blacksheep.org; Wed, 02 Dec 2009 18:07:48 +0000 Received: from [83.244.159.144] (helo=relay3.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NFtcB-0006WP-LM for rsgb_lf_group@blacksheep.org; Wed, 02 Dec 2009 18:07:47 +0000 Received: from mbox1.netikka.net ([213.250.81.202]) by relay3.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NFtc9-0006wC-Ot for rsgb_lf_group@blacksheep.org; Wed, 02 Dec 2009 18:07:47 +0000 Received: from tupu.netikka.net (tupu [172.16.83.90]) by mbox1-feedback.netikka.net (Postfix) with ESMTP id 32B47188031 for ; Wed, 2 Dec 2009 20:07:40 +0200 (EET) Received: from imp1.netikka.net (imp1.netikka.net [213.250.85.154]) by tupu.netikka.net (Postfix) with ESMTP id EC08A4B0058 for ; Wed, 2 Dec 2009 20:07:39 +0200 (EET) Received: from localhost (localhost [127.0.0.1]) by imp1.netikka.net (Postfix) with ESMTP id 2BC55495BCB for ; Wed, 2 Dec 2009 20:07:40 +0200 (EET) Received: from 558602b6.adsl.multi.fi (558602b6.adsl.multi.fi [85.134.2.182]) by imp.netikka.net (IMP) with HTTP for ; Wed, 02 Dec 2009 20:07:40 +0200 Message-ID: <1259777260.4b16acec27aa8@imp.netikka.net> Date: Wed, 02 Dec 2009 20:07:40 +0200 From: Paul-Henrik To: rsgb_lf_group@blacksheep.org References: <38A51B74B884D74083D7950AD0DD85E828AAF4@File-Server-HST.hst.e-technik.tu-darmstadt.de> In-Reply-To: MIME-Version: 1.0 User-Agent: Internet Messaging Program (IMP) 3.2.6 X-Originating-IP: 85.134.2.182 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: Re: LF: Results of optimising an active antenna Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=none autolearn=no version=2.63 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-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) Hello Stefan, LF I can not overemphasize the possible need to keep the feedline "clean" and= free of RFI that may otherwise make it's way to any active whip antenna. My first attempts at deploying the PA0RDT Mini-Whip here were unsuccessful= and disappointing due to the fact that some of the RFI I tried to avoid was conducted from the shack out to the antenna along the coax. This may among other things depend on what kind of radio the antenna is connected to. If in doubt, my advice is to use one common mode choke where the coax leav= es the house and to ground the coax braid just behind it using an independent earth-stake and then further a second common-mode choke just before the feedline goes vertically up to the antenna. For common mode chokes I use large high-mu ferrite rings that can take 20= turns of RG-58 or up to 45 turns of RG-174 but smaller rings can be used with RG= -174. There is a picture here of the first test-choke I used for tracking down= my noise: http://peditio.net/utility/Attachments/choke_sml.jpg This may be "overkill" in most installations but I'm sure some users can= gain from these extra measures just as I did. BR Paul-Henrik, OH1LSQ