Return-Path: Received: from mtain-me06.r1000.mx.aol.com (mtain-me06.r1000.mx.aol.com [172.29.96.142]) by air-df02.mail.aol.com (v129.4) with ESMTP id MAILINDF024-5ee94ca0d8bc13a; Mon, 27 Sep 2010 13:47:40 -0400 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-me06.r1000.mx.aol.com (Internet Inbound) with ESMTP id D7EDE3800016E; Mon, 27 Sep 2010 13:47:38 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1P0HmM-0002gS-Bh for rs_out_1@blacksheep.org; Mon, 27 Sep 2010 18:46:18 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1P0HmB-0002g1-TA for rsgb_lf_group@blacksheep.org; Mon, 27 Sep 2010 18:46:07 +0100 Received: from mail-bw0-f43.google.com ([209.85.214.43]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1P0HmB-00057C-JZ for rsgb_lf_group@blacksheep.org; Mon, 27 Sep 2010 18:46:09 +0100 Received: by bwz16 with SMTP id 16so4768057bwz.16 for ; Mon, 27 Sep 2010 10:46:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type; bh=+fMIhBv2v5ojGSe58JZNDKu9nm+Nw6iQQ1KWG0p7PVk=; b=woX/ZjuPHGordfO1dHhxDKNu6D1M5TJDRBDNT3sKvDgSA/b60w4hUbc8L9/yUXLwAH y806pjqw3cU1d7eCme9zVgQw977RWPl/rTQ5txH+VJQCg5f8uRq1HI0FrdybAZSZJ+k3 lF8dQBvxQWeQz40Cn+9I7xphfcifZsIFrchIE= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=eFAIapZWdE2ZdFf/sO6Grnt7AZ7gw96QP48QIBnSSZdOZGIqsp7fcC4zZ95t9H+PJH 5eNM9WujbYPriUNObNX3SNrx7z8OTjdMaen0hNNBLDzJTj3pYDtSBKG1sZ0bVKtKnsDj /FNf++AhbshW9hn0XDI62hmxR2xr/x/AgftAc= MIME-Version: 1.0 Received: by 10.103.123.1 with SMTP id a1mr807635mun.101.1285609488939; Mon, 27 Sep 2010 10:44:48 -0700 (PDT) Received: by 10.220.200.193 with HTTP; Mon, 27 Sep 2010 10:44:48 -0700 (PDT) In-Reply-To: References: Date: Mon, 27 Sep 2010 13:44:48 -0400 Message-ID: From: Warren Ziegler To: rsgb_lf_group@blacksheep.org DomainKey-Status: good (testing) 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=0016e649c9d2e9f5a70491414815 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.1 required=5.0 tests=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-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-d226.2 ; domain : gmail.com DKIM : pass X-AOL-REROUTE: YES x-aol-sid: 3039ac1d608e4ca0d8ba6052 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) --0016e649c9d2e9f5a70491414815 Content-Type: text/plain; charset=ISO-8859-1 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 spaced 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! There can be considerable potential differences from loop to ground! Why would you want to consider dissipating transmitter power by creating a leakage path to ground? -- 73 Warren K2ORS WD2XGJ 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 the 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 attempt 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 best 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: > > - What additional losses, if any, do I suffer having the loop on the > ground (even wet ground)? How do these arise? > - Could I bury the return part of the loop wire in the ground and maybe > gain a few more square metres of area? > - Is there anywhere where I can get a simple explanation of loop 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 wondering if the > "loop must be in the air and away from foliage" is another accepted "fact" > which needs to be questioned. > > 73s > Roger G3XBM > > -- > http://g3xbm-qrp.blogspot.com/ > http://www.g3xbm.co.uk > http://www.youtube.com/user/g3xbm > G3XBM GQRP 1678 ISWL G11088 > --0016e649c9d2e9f5a70491414815 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Roger,

=A0=A0 =A0 =A0 =A0I run a TX loop at the 1.2 kW= level. The loop is made up of two turns of coax 24m vertical by 44m horiz= ontal, the turns are spaced 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!=A0
There can be considerable potential differences from loop to ground!= =A0

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

--=A0<= br>73 Warren K2ORS
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WD2XGJ=A0
=A0 =A0 =A0 =A0 =A0 =A0 =A0= =A0 WD2XSH/23
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WE2XEB/2
=A0 =A0 =A0= =A0 =A0 =A0 =A0 =A0 WE2XGR/1


On Mon, Sep 27, 2010 at 1:24 PM, Roger Lapthorn <rogerlapthorn@gmail.com> wrote:
Good to see the reflector back again.
=
For the last week or so I've been running my vertical "fully= in the 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= attempt 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 (act= ually better) than my top loaded Marconi used last winter with best 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 di= fferent WSPR reports out to 148km. I clearly know that improving the wire= diameter will improve the ERP=20 simply as a result of reducing resistive losses. What I'm less clear= =20 about is why people say all of the loop should be raised above the=20 ground.

My questions are these:
  • What additional losses,= if any, do I suffer having the loop on the ground (even wet ground)? How= do these arise?
  • Could I bury the return part of the loop wire= in the ground and maybe gain a few more square metres of area?
  • Is there anywhere where I can get a simple explanation of loop 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 wondering if the "loop must= be in the air and away from foliage" is another accepted "fact&= quot; which needs to be questioned.

73s
Roger G3XBM

--
http://g3xbm-qrp.blogspot.= com/
http://ww= w.g3xbm.co.uk
http://www= .youtube.com/user/g3xbm
G3XBM=A0=A0 GQRP 1678=A0=A0=A0 ISWL G11088




=A0
--0016e649c9d2e9f5a70491414815--