X-GM-THRID: 1198237036359000497 X-Gmail-Labels: rsgb lf X-Gmail-Received: 8c7dafdd977933d7db80f240b65a8c75d6900af6 Delivered-To: daveyxm@gmail.com Received: by 10.54.70.14 with SMTP id s14cs22504wra; Sun, 19 Mar 2006 08:18:01 -0800 (PST) Received: by 10.66.255.2 with SMTP id c2mr1232802ugi; Sun, 19 Mar 2006 08:18:00 -0800 (PST) Return-Path: Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mx.gmail.com with ESMTP id k1si946564ugf.2006.03.19.08.17.59; Sun, 19 Mar 2006 08:18:00 -0800 (PST) Received-SPF: neutral (gmail.com: 193.82.116.20 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1FL0Zh-0005mW-2r for rs_out_1@blacksheep.org; Sun, 19 Mar 2006 16:16:13 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1FL0Zg-0005mN-CR for rsgb_lf_group@blacksheep.org; Sun, 19 Mar 2006 16:16:12 +0000 Received: from [64.97.136.176] (helo=n064.sc1.cp.net) by relay1.thorcom.net with esmtp (Exim 4.51) id 1FL2AY-0008Oc-EP for rsgb_lf_group@blacksheep.org; Sun, 19 Mar 2006 17:58:38 +0000 Received: from your4105e587b6 (62.252.204.240) by n064.sc1.cp.net (7.2.069.1) id 440E1EF30016E1C7 for rsgb_lf_group@blacksheep.org; Sun, 19 Mar 2006 16:13:39 +0000 Message-ID: <001b01c64b70$12d8b450$3bcdfc3e@your4105e587b6> From: "g3kev" To: References: <000901c64aab$8824e460$1ce4fc3e@your4105e587b6> <002101c64adb$e5924720$6211f4cc@p1i5f0> <007401c64aeb$4b30d7e0$0600000a@quaycustomer> <001f01c64b4d$f258aae0$023c7ad5@w4o8m9> Date: Sun, 19 Mar 2006 16:12:59 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Spam-Score: -1.0 (-) X-Spam-Report: autolearn=disabled,AWL=-1.290,HTML_40_50=0.086,HTML_FONT_BIG=0.232,HTML_MESSAGE=0.001 Subject: LF: Re: Re: LOOPS V VERTICALS Content-Type: multipart/alternative; boundary="----=_NextPart_000_0017_01C64B6F.FDE69D00" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.6 required=5.0 tests=HTML_20_30,HTML_FONT_BIG, HTML_MESSAGE 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 Status: O X-Status: X-Keywords: X-UID: 5979 This is a multi-part message in MIME format. ------=_NextPart_000_0017_01C64B6F.FDE69D00 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit ----- Original Message ----- From: James Moritz To: rsgb_lf_group@blacksheep.org Sent: Sunday, March 19, 2006 12:09 PM Subject: LF: Re: LOOPS V VERTICALS Jim you are confusing the discussion by introducing a noisy local enverionment, where no doubt its a loop or nothing to null out the noise. My argument made it clear that I was considering the merits of loops v verticals especially the smaller ones in a good quiet environment, the only way to compare both as regards efficiency and signal capture. de Mal/G3KEV The argument about loops and verticals in noisy locations has been discussed many times before. Dear LF Group, At M0BMU, the original motivation for using seperate RX antennas was the increasing 50Hz-related noise level on the TX vertical. This seems to be due to pick-up from the house mains wiring, but moving the vertical further from the house would result in reduced possible length, and it is short enough already! Remote vertical antennas worked fine as far as eliminating mains noise was concerned, but did nothing to reduce distant sources of QRM such as Loran. Here I have to use quite selective antennas (the broadband active-whip type of antenna is not really workable here due to the 20V/m MF signal levels from Brookmans Park). For some time I used single loops oriented to null out the Lessay Loran signal, and I estimated this reduced the noise floor for most European signals by 6dB or so, which made quite a few more stations audible. I found that much experimentation was needed to find suitable positions for the loops where they would null out Loran, but not pick up 50Hz noise at the same time - loops seem to be more sensitive to this type of QRM. Then the Rugby Loran started up, and the band noise level in aural reception bandwidths (e.g. 300Hz) increased by 15dB, wiping out many of the weaker signals at this QTH. I countered this using both loop and vertical antennas phased together to provide two adjustable nulls aimed at Rugby and Lessay. This brought the situation for aural reception of European sigs to about the same place as it was before - but most signals coming from the west are attenuated by the overall directional properties of the system. So, for aural signal reception at this location in SE England, currently neither loops nor vertical antennas by themselves work very well, allthough quite good results are achieved by using a phasing system with both types of antenna to null out the Loran. For narrow-band QRSS, etc. signals, the situation is different, since provided the received signal frequency does not coincide with a Loran line, Loran does not matter too much. There does not seem to be much to choose between the loop and the vertical most of the time, however under quiet band conditions with little QRN I have found that if I use the phased loop and vertical antennas, and reverse the relative phase of the antennas to favour signals from the west (i.e. for transatlantic reception), the band noise is reduced by several dB on the spectrogram compared to either antenna by itself - I suspect this may be due to a reduction in "Luxembourg effect" noise originating from Europe to the east. So here I find it neccessary to use both types of antenna simultaneously, if I want to achieve good results. This is mostly to overcome the effects of man-made QRM and to enable aural reception of signals, which are perhaps the main differences between my situation and the others who have commented. Cheers, Jim Moritz 73 de M0BMU ------=_NextPart_000_0017_01C64B6F.FDE69D00 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
 
----- Original Message -----
From:=20 James Moritz
Sent: Sunday, March 19, 2006 = 12:09=20 PM
Subject: LF: Re: LOOPS V = VERTICALS
 
 
 
 
Jim you are confusing = the=20 discussion by introducing a noisy local enverionment, where no doubt = its a=20 loop or nothing to null out the noise.
My argument made it = clear that I=20 was considering the merits of loops v verticals especially the smaller = ones in=20 a good quiet environment, the only way to compare both as regards = efficiency=20 and signal capture.
de = Mal/G3KEV
 
The argument about = loops and=20 verticals in noisy locations has been discussed many times=20 before.
 

Dear LF Group,
 
At M0BMU, the original motivation for = using=20 seperate RX antennas was the increasing 50Hz-related noise level = on the=20 TX vertical. This seems to be due to pick-up from the house mains = wiring, but=20 moving the vertical further from the house would result in reduced = possible=20 length, and it is short enough already!
 
Remote vertical antennas = worked fine as far=20 as eliminating mains noise was concerned, but did nothing to = reduce=20 distant sources of QRM such as Loran. Here I have to use quite = selective=20 antennas (the broadband active-whip type of antenna is not really = workable=20 here due to the 20V/m MF signal levels from Brookmans Park). For some = time I=20 used single loops oriented to null out the Lessay Loran = signal, and I=20 estimated this reduced the noise floor for most European signals by = 6dB or so,=20 which made quite a few more stations audible. I found that much=20 experimentation was needed to find suitable positions for the loops = where they=20 would null out Loran, but not pick up 50Hz noise at the same time - = loops seem=20 to be more sensitive to this type of QRM.
 
Then the Rugby Loran started up, and = the band=20 noise level in aural reception bandwidths (e.g. 300Hz) increased by = 15dB,=20 wiping out many of the weaker signals at this QTH. I countered = this=20 using both loop and vertical antennas phased together to provide = two=20 adjustable nulls aimed at Rugby and Lessay. This brought the situation = for=20 aural reception of European sigs to about the same place as it was = before -=20 but most signals coming from the west are attenuated by the overall=20 directional properties of the system.
 
So, for aural=20 signal reception at this location in SE England, currently = neither  loops=20 nor vertical antennas by themselves work very well, allthough quite = good=20 results are achieved by using a phasing system with both types of = antenna to=20 null out the Loran.
 
For narrow-band QRSS, etc. signals, = the situation=20 is different, since provided the received signal frequency does not = coincide=20 with a Loran line, Loran does not matter too much. There does not seem = to be=20 much to choose between the loop and the vertical most of the time, = however=20 under quiet band conditions with little QRN I have found that if I use = the=20 phased loop and vertical antennas, and reverse the relative phase of = the=20 antennas to favour signals from the west (i.e. for transatlantic = reception),=20 the band noise is reduced by several dB on the spectrogram compared to = either=20 antenna by itself - I suspect this may be due to a reduction in=20 "Luxembourg effect" noise originating from Europe to the = east.
 
So here I find it neccessary to = use both=20 types of antenna simultaneously, if I want to achieve good results. = This is=20 mostly to overcome the effects of man-made QRM and to enable aural = reception=20 of signals, which are perhaps the main differences between my = situation and=20 the others who have commented.
 
Cheers, Jim Moritz
73 de = M0BMU
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