Return-Path: Received: from mtain-de12.r1000.mx.aol.com (mtain-de12.r1000.mx.aol.com [172.29.64.212]) by air-di08.mail.aol.com (v129.4) with ESMTP id MAILINDI082-eb674c6a7712ea; Tue, 17 Aug 2010 07:48:34 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-de12.r1000.mx.aol.com (Internet Inbound) with ESMTP id B498638000099; Tue, 17 Aug 2010 07:48:32 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OlKdn-0003EE-L3 for rs_out_1@blacksheep.org; Tue, 17 Aug 2010 12:47:39 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OlKdn-0003E5-3Z for rsgb_lf_group@blacksheep.org; Tue, 17 Aug 2010 12:47:39 +0100 Received: from relay.uni-heidelberg.de ([129.206.100.212]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1OlKdm-0006LN-2q for rsgb_lf_group@blacksheep.org; Tue, 17 Aug 2010 12:47:39 +0100 Received: from freitag.iup.uni-heidelberg.de (freitag.iup.uni-heidelberg.de [129.206.29.204]) by relay.uni-heidelberg.de (8.14.1/8.14.1) with ESMTP id o7HBlBvS006095 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Tue, 17 Aug 2010 13:47:12 +0200 Received: from [129.206.29.99] (pc99.iup.uni-heidelberg.de [129.206.29.99]) by freitag.iup.uni-heidelberg.de (8.12.11.20060308/8.11.2) with ESMTP id o7HBlbV5019676 for ; Tue, 17 Aug 2010 13:47:37 +0200 Message-ID: <4C6A767E.3080103@iup.uni-heidelberg.de> Date: Tue, 17 Aug 2010 13:46:06 +0200 From: =?ISO-8859-15?Q?Stefan_Sch=E4fer?= User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <4C694CC6.3010609@o2.ie> <1282007441.6432.12.camel@vaio3rd> <1282014113.6432.22.camel@vaio3rd> <1282025562.6432.54.camel@vaio3rd> <000f01cb3de6$040e2780$0301a8c0@your91hoehfy9g> <1282036245.6432.81.camel@vaio3rd> <4C6A5A2D.4040803@iup.uni-heidelberg.de> <002501cb3dfa$26bf9840$0301a8c0@your91hoehfy9g> <4C6A710C.2030603@iup.uni-heidelberg.de> <003e01cb3e00$b7865f70$0301a8c0@your91hoehfy9g> In-Reply-To: <003e01cb3e00$b7865f70$0301a8c0@your91hoehfy9g> X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,RATWARE_GECKO_BUILD=1.426 Subject: Re: LF: Earth electrodes antenna tests[Contest results] Content-Type: multipart/alternative; boundary="------------060505090606070108040508" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.8 required=5.0 tests=HTML_30_40,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: 3039ac1d40d44c6a77106271 X-AOL-IP: 193.82.116.20 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) --------------060505090606070108040508 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by relay.uni-heidelberg.de id o7HBlBvS006095 Mal, I am using a galvanic decoupled primary winding at the bottom of the=20 water barrel where the coil is wound on. Adjust the primary number of=20 turns so that enough power is fed into the system. Watch the photo on my= =20 qrz.com page named "new amperemeter". There you see the primary winding=20 just above the amperemeter. 73, Stefan Am 17.08.2010 13:38, schrieb mal hamilton: > Stefan > I am talking about matching the amp 8 ohms to 50 ohms not about=20 > resonating the antenna. My antenna is already resonated for 9 Kcs, or=20 > 137 as required. > I was referring to your kite antenna and what method you used for=20 > matching amp to antenna. > de mal/g3kev > > ----- Original Message ----- > *From:* Stefan Sch=E4fer > *To:* rsgb_lf_group@blacksheep.org > > *Sent:* Tuesday, August 17, 2010 12:22 PM > *Subject:* Re: LF: Earth electrodes antenna tests[Contest results] > > Mal, > > Are you talking about a earth electrode antenna or your vertical > antenna? I assume you mean the vertical ;-) > > You will get several kV, most probably above 10 kV rms on your > antenna. That's why a ferrite transformer is not a good choice for > a large ( C ) antenna in addition with QRO! For your 5 W tests it > may work with a ferrite coil L but not at 500 W and above. > > There is _no_ alternative to wind an air coil if you want to > generate a signal that can be watched in the far field. > > And if you want to generate a signal that can be heared in CW > across EU i recommend a power supply like i had as i worked in > Darmstadt last year: > http://www.hst.tu-darmstadt.de/index.php?id=3D173&L=3D1 ;-) > > Transforming to 50 Ohm is not wrong but it is not necessary. You > can just resonate the antenna and match the load to something > suitable for the audio amp (4...8 Ohm). A 50 Ohm impedance level > is just necessary if you want to filter your signal with a precise > dimensioned low pass filter that properly works at 50 Ohm input > and output impedance (in my opinion). Essential is, that the power > is pushed into the antenna! ;-) > > 73, Stefan > > PS: On an earth antenna, which is not resonated (!), you just have > to apply a proper output voltage to the antenna that causes the DC > input power at the PA that you want to generate. > > > Am 17.08.2010 12:51, schrieb mal hamilton: >> Stefan >> What method do u use to couple the amplifier to the electrodes? Is= the amp >> output impedence 8 ohms. >> My method for my antenna using an audio amp would be to use a ferri= te >> transformer to step up the 8 ohms to 50 ohms (x 6.250) turns Prim= 8 and >> Secondary 20 turns. This way I can use my existing test equipment= for swr >> etc. >> mal/g3kev >> =20 >> --------------060505090606070108040508 Content-Type: text/html; charset=ISO-8859-15 Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by relay.uni-heidelberg.de id o7HBlBvS006095 Mal,

I am using a galvanic decoupled primary winding at the bottom of the water barrel where the coil is wound on. Adjust the primary number of turns so that enough power is fed into the system. Watch the photo on my qrz.com page named "new amperemeter". There you see the primary winding just above the amperemeter.

73, Stefan


Am 17.08.2010 13:38, schrieb mal hamilton:
Stefan
I am talking about matching the amp 8 ohms to 50 ohms not about resonating the antenna. My antenna is already resonated for 9 Kcs, or 137 as required.
I was referring to your kite antenn= a and what method you used for matching amp to antenna.
de mal/g3kev
=A0
----- Original Message -----
Sent: Tuesday, August 17, 2010 12:22 PM
Subject:= Re: LF: Earth electrodes antenna tests[Contest results]

Mal,

Are you talking about a earth electrode antenna or your vertical antenna? I assume you mean the vertical ;-)

You will get several kV, most probably above 10 kV rms on your antenna. That's why a ferrite transformer is not a good choice for a large ( C ) antenna in addition with QRO! For your 5 W tests it may work with a ferrite coil L but not at 500 W and above.

There is no alternative to wind an air coil if you want to generate a signal that can be watched in the far field.

And if you want to generate a signal that can be heared in CW across EU i recommend a power supply like i had as i worked in Darmstadt last year: http://ww= w.hst.tu-darmstadt.de/index.php?id=3D173&L=3D1 ;-)

Transforming to 50 Ohm is not wrong but it is not necessary. You can just resonate the antenna and match the load to something suitable for the audio amp (4...8 Ohm). A 50 Ohm impedance level is just necessary if you want to filter your signal with a precise dimensioned low pass filter that properly works at 50 Ohm input and output impedance (in my opinion). Essential is, that the power is pushed into the antenna! ;-)

73, Stefan

PS: On an earth antenna, which is not resonated (!), you just have to apply a proper output voltage to the antenna that causes the DC input power at the PA that you want to generate.


Am 17.08.2010 12:51, schrieb mal hamilton: 
Stefan
What method do u use to couple the amplifier to the electrodes? Is the amp
output impedence 8 ohms.
My method for my antenna using an audio amp would be to use a ferrite
transformer to step up the 8  ohms to 50 ohms (x 6.250) turns Prim 8 and
Secondary 20 turns. This way I can use my existing test equipment for swr
etc.
mal/g3kev

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