Return-Path: Received: from mtain-dh01.r1000.mx.aol.com (mtain-dh01.r1000.mx.aol.com [172.29.65.21]) by air-ma10.mail.aol.com (v129.4) with ESMTP id MAILINMA102-b5414d8a80c988; Wed, 23 Mar 2011 19:22:49 -0400 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dh01.r1000.mx.aol.com (Internet Inbound) with ESMTP id A60C7380000A2; Wed, 23 Mar 2011 19:22:47 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Q2XMi-0006dn-61 for rs_out_1@blacksheep.org; Wed, 23 Mar 2011 23:21:24 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Q2XMh-0006de-JM for rsgb_lf_group@blacksheep.org; Wed, 23 Mar 2011 23:21:23 +0000 Received: from relay2.uni-heidelberg.de ([129.206.210.211]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Q2XMf-0001UV-Kq for rsgb_lf_group@blacksheep.org; Wed, 23 Mar 2011 23:21:23 +0000 Received: from ix.urz.uni-heidelberg.de (cyrus-portal.urz.uni-heidelberg.de [129.206.100.176]) by relay2.uni-heidelberg.de (8.13.8/8.13.8) with ESMTP id p2NNLKuM025648 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Thu, 24 Mar 2011 00:21:20 +0100 Received: from extmail.urz.uni-heidelberg.de (extmail.urz.uni-heidelberg.de [129.206.100.140]) by ix.urz.uni-heidelberg.de (8.13.8/8.13.8) with ESMTP id p2NNLJOa010307 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Thu, 24 Mar 2011 00:21:19 +0100 Received: from [147.142.8.35] (vpn508-035.rzuser.uni-heidelberg.de [147.142.8.35]) by extmail.urz.uni-heidelberg.de (8.13.4/8.13.1) with ESMTP id p2NNLASs008545 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Thu, 24 Mar 2011 00:21:16 +0100 Message-ID: <4D8A8074.9000303@iup.uni-heidelberg.de> Date: Thu, 24 Mar 2011 00:21:24 +0100 From: =?UTF-8?B?U3RlZmFuIFNjaMOkZmVy?= User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.11) Gecko/20100711 Thunderbird/3.0.6 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <4D83D475.9090609@telus.net> <000b01cbe622$6a23f8d0$8d01a8c0@JAYDELL>, ,<4D86BD6F.8020006@telus.net> <4D8736CB.8040509@telus.net> <4D87E247.5020100@iup.uni-heidelberg.de> <8CDB69E4AD7AA3C-1490-33A81@webmail-m018.sysops.aol.com> <4D894947.6020405@iup.uni-heidelberg.de> <4D898B6C.2040403@telus.net> In-Reply-To: <4D898B6C.2040403@telus.net> X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,RATWARE_GECKO_BUILD=1.426 Subject: Re: VLF: Resonate the antenna, or not? Content-Type: multipart/alternative; boundary="------------000101030802050004070204" 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=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: G x-aol-sid: 3039ac1d41154d8a80c638e0 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) --------------000101030802050004070204 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Wow, nice! Rik/ON7YD, now its your turn again: What will be the ERP when running 100A in that wire? I think 100A is realistic on such a wire. Skin depth should be 0.9 mm. So the effective conductor area 19 mm^2. Assuming 20m x 30m (?) wire (=600m^2) means 100m length, so R ~ 0.15 Ohm. So Scott gets 100 A rms when running 1.5 kW into the antenna (no problem for the mains), without having problems of winding a large coil, without resonating, without ferrite parts, without high voltages (but high currents ;-) ). Am i right, Rik? And what is the ERP? I could take a look on your website but you can do it so well here! What is the L and Z and so the needed voltage to get 100A? :-) Instead of standard FETs, some IGBTs could be used, shouldn't be a problem at 9 kHz and some 100V. Any recommendations? :-) Scott, what FETs do you use in your design? The IRFP460 is OK for 20 A but not much more. One could do the effort and switch 4x 10 of them in parallel but you'll need a good driver, maybe IXDD430... Interesting stuff! 73, Stefan EI/DK7FC Am 23.03.2011 06:55, schrieb Scott Tilley: > Hi Stefan >> The mains has just to supply the losses. So the critical parts are >> the FETs and the loop wire diameter. I think 100 A rms is a problem >> for most loops. But i would give it a try. Even the 4x or 5x 1.5 mm^2 >> could take that current for a while, depending on the outside >> temperature. BTW there will be a current limiting when the >> temperature increases :-) > The loop here is a #2 AWG (6.5mm) AL conductor. And yes I note > considerable difference between cold days and warm ones on 2200m. > Somewhere I have some measurements. > >> >> Who is the one who does the first test? Scott? :-) BTW the distance >> between VE7TIL and KL7UK is just 2084 km! >> http://no.nonsense.ee/qthmap/?qth=CN89DK&from=bp51ip >> > I pulled the h-bridge design of yours from my files and found a > version of this in my junk box... Now the magic question is when can > I find time to rig this up? > >> Scott, what do you estimate is the current limit of your loop wire >> and what is the area? And what is the bearing? > > Easily a couple hundred amps. 600m^2 and aimed right at Laurence. > See my website 'station info.' >> >> 73, Stefan/ EI/DK7FC >> >> > --------------000101030802050004070204 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by relay2.uni-heidelberg.de id p2NNLKuM025648 Wow, nice!

Rik/ON7YD, now its your turn again: What will be the ERP when running 100A in that wire? I think 100A is realistic on such a wire. Skin depth should be 0.9 mm. So the effective conductor area 19 mm^2. Assuming 20m x 30m (?) wire (=3D600m^2) means 100m length, so R ~ 0.15 Ohm. So Scott gets 100 A rms when running 1.5 kW into the antenna (no problem for the mains), without having problems of winding a large coil, without resonating, without ferrite parts, without high voltages (but high currents ;-) ). Am i right, Rik? And what is the ERP? I could take a look on your website but you can do it so well here! What is the L and Z and so the needed voltage to get 100A? :-)
Instead of standard FETs, some IGBTs could be used, shouldn't be a problem at 9 kHz and some 100V. Any recommendations? :-)

Scott, what FETs do you use in your design? The IRFP460 is OK for 20 A but not much more. One could do the effort and switch 4x 10 of them in parallel but you'll need a good driver, maybe IXDD430... Interesting stuff!

73, Stefan EI/DK7FC

Am 23.03.2011 06:55, schrieb Scott Tilley:
Hi Stefan
=C2=A0 The mains has just to supply the losses. So the critical parts are the FETs and the loop wire diameter. I think 100 A rms is a problem for most loops. But i would give it a try. Even the 4x or 5x 1.5 mm^2 could take that current for a while, depending on the outside temperature. BTW there will be a current limiting when the temperature increases :-)
The loop here is a #2 AWG (6.5mm) AL conductor.=C2=A0 And yes I note considerable difference between cold days and warm ones on 2200m.=C2=A0 Somewhere I have some measurements.


Who is the one who does the first test? Scott? :-) BTW the distance between VE7TIL and KL7UK is just 2084 km! http://no.nonsense.ee/qthmap/?qth=3DCN89DK&am= p;from=3Dbp51ip

I pulled the h-bridge design of yours from my files and found a version of this in my junk box...=C2=A0 Now the magic question is when can I find time to rig this up?

Scott, what do you estimate is the current limit of your loop wire and what is the area? And what is the bearing?

Easily a couple hundred amps.=C2=A0 600m^2 and aimed right at Laurence.=C2= =A0 See my website 'station info.'

73, Stefan/ EI/DK7FC



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