Return-Path: Received: from mtain-da01.r1000.mx.aol.com (mtain-da01.r1000.mx.aol.com [172.29.64.73]) by air-dd06.mail.aol.com (v129.4) with ESMTP id MAILINDD063-865c4ca0dbb721f; Mon, 27 Sep 2010 14:00:23 -0400 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-da01.r1000.mx.aol.com (Internet Inbound) with ESMTP id 689A0380000F9; Mon, 27 Sep 2010 14:00:21 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1P0HyS-00031r-Fe for rs_out_1@blacksheep.org; Mon, 27 Sep 2010 18:58:48 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1P0HyI-00031i-0H for rsgb_lf_group@blacksheep.org; Mon, 27 Sep 2010 18:58:38 +0100 Received: from out1.ip09ir2.opaltelecom.net ([62.24.128.245]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1P0HyH-0005Eo-2K for rsgb_lf_group@blacksheep.org; Mon, 27 Sep 2010 18:58:39 +0100 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AlsFAAp4oExOk8J1/2dsb2JhbACQJAOGSosmcckihUQEgVyLcoJM X-IronPort-AV: E=Sophos;i="4.57,244,1283727600"; d="scan'208,217";a="450223601" Received: from unknown (HELO xphd97xgq27nyf) ([78.147.194.117]) by out1.ip09ir2.opaltelecom.net with SMTP; 27 Sep 2010 18:58:31 +0100 Message-ID: <008701cb5e6d$978bf850$0401a8c0@xphd97xgq27nyf> From: "mal hamilton" To: References: Date: Mon, 27 Sep 2010 18:58:29 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: Loops on TX Content-Type: multipart/alternative; boundary="----=_NextPart_000_0084_01CB5E75.F9230EC0" 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_FONTCOLOR_UNSAFE,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 x-aol-global-disposition: S X-AOL-REROUTE: YES x-aol-sid: 3039ac1d40494ca0dbb46aa7 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none ------=_NextPart_000_0084_01CB5E75.F9230EC0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Warren This is correct and to bury the bottom wire is even worse except one= wants to grow date palms around the artic circle g3kev ----- Original Message -----=20 From: Warren Ziegler=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Monday, September 27, 2010 6:44 PM Subject: Re: LF: Loops on TX Roger, I run a TX loop at the 1.2 kW level. The loop is made up of= two turns of coax 24m vertical by 44m horizontal, the turns are space= d 3m apart and they are in parallel. I can show you where the loop conductor came into contact with wet= foliage and burned through the insulation of the coax!=20 There can be considerable potential differences from loop to ground!= =20 Why would you want to consider dissipating transmitter power by crea= ting a leakage path to ground? --=20 73 Warren K2ORS WD2XGJ=20 WD2XSH/23 WE2XEB/2 WE2XGR/1 On Mon, Sep 27, 2010 at 1:24 PM, Roger Lapthorn wrote: Good to see the reflector back again. For the last week or so I've been running my vertical "fully in th= e air" TX loop (1mm diameter wire, 80m sq area) on both 137 and 500kHz= . Now, the bottom of the loop is laying right on the lawn with no atte= mpt to raise it off the ground. Weather has been mixed and yesterday= it rained all day. Results on 500kHz suggest it is every bit as good= (actually better) than my top loaded Marconi used last winter with be= st DX so far with 2mW ERP being LA3EQ last evening (heavy rain all day= and evening). Results on 136kHz with <20uW ERP have been encouraging= too with 6 different WSPR reports out to 148km. I clearly know that= improving the wire diameter will improve the ERP simply as a result= of reducing resistive losses. What I'm less clear about is why people= say all of the loop should be raised above the ground. My questions are these: a.. What additional losses, if any, do I suffer having the loop= on the ground (even wet ground)? How do these arise? b.. Could I bury the return part of the loop wire in the ground= and maybe gain a few more square metres of area?=20 c.. Is there anywhere where I can get a simple explanation of lo= op losses due to ground presence and foliage presence? In the last year a lot of accepted theory/beliefs, for example on= earth electrode antennas, has proved to be questionable and I am wond= ering if the "loop must be in the air and away from foliage" is anothe= r accepted "fact" which needs to be questioned. 73s Roger G3XBM --=20 http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/g3xbm G3XBM GQRP 1678 ISWL G11088 =20 ------=_NextPart_000_0084_01CB5E75.F9230EC0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Warren
This is correct and to bury the botto= m wire is even=20 worse except one wants to grow date palms around the artic circle
g3kev
 
----- Original Message -----
From:=20 Warren= Ziegler=20
Sent: Monday, September 27,= 2010 6:44=20 PM
Subject: Re: LF: Loops on TX<= /DIV>

Roger,

        I run a TX loop at the 1.2 kW= level. The=20 loop is made up of two turns of coax 24m vertical by 44m horizontal,= the turns=20 are spaced 3m apart and they are in parallel.
I can show you where the loop conductor came into contact with= wet=20 foliage and burned through the insulation of the coax! 
There can be considerable potential differences from loop to=20 ground! 

Why would you want to consider dissipating transmitter power by= creating=20 a leakage path to ground?

-- 
73 Warren K2ORS
       =  =20       WD2XGJ 
        &nb= sp;  =20     WD2XSH/23
           =  =20   WE2XEB/2
             =  =20 WE2XGR/1


On Mon, Sep 27, 2010 at 1:24 PM, Roger Lapt= horn <rogerlapthorn@gmail.com>=20 wrote:
Good=20 to see the reflector back again.

For the last week or so I'= ve been=20 running my vertical "fully in the air" TX loop (1mm diameter wire,= 80m sq=20 area) on both 137 and 500kHz. Now, the bottom of the loop is layin= g right on=20 the lawn with no attempt to raise it off the ground. Weather has= been mixed=20 and yesterday it rained all day. Results on 500kHz suggest it is= every bit=20 as good (actually better) than my top loaded Marconi used last win= ter with=20 best DX so far with 2mW ERP being LA3EQ last evening (heavy rain= all day and=20 evening). Results on 136kHz with <20uW ERP have been encouragin= g too with=20 6 different WSPR reports out to 148km. I clearly know that improvi= ng the=20 wire diameter will improve the ERP simply as a result of reducing= resistive=20 losses. What I'm less clear about is why people say all of the loo= p should=20 be raised above the ground.

My questions are these:
  • What additional losses, if any, do I suffer having the loop= on the=20 ground (even wet ground)? How do these arise?
  • Could I bury the return part of the loop wire in the ground= and maybe=20 gain a few more square metres of area?=20
  • Is there anywhere where I can get a simple explanation of lo= op losses=20 due to ground presence and foliage presence?
In the las= t year a lot=20 of accepted theory/beliefs, for example on earth electrode antenna= s, has=20 proved to be questionable and I am wondering if the "loop must be= in the air=20 and away from foliage" is another accepted "fact" which needs to= be=20 questioned.

73s
Roger G3XBM
--
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/g3xbm
G3XBM  =20 GQRP 1678    ISWL G11088




 
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