Return-Path: Received: from mtain-di02.r1000.mx.aol.com (mtain-di02.r1000.mx.aol.com [172.29.64.6]) by air-mb07.mail.aol.com (v129.4) with ESMTP id MAILINMB072-a7854c6a9f3914e; Tue, 17 Aug 2010 10:39:53 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-di02.r1000.mx.aol.com (Internet Inbound) with ESMTP id 281BA3800012A; Tue, 17 Aug 2010 10:39:51 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OlNJH-0004tM-A1 for rs_out_1@blacksheep.org; Tue, 17 Aug 2010 15:38:39 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OlNJG-0004tD-O6 for rsgb_lf_group@blacksheep.org; Tue, 17 Aug 2010 15:38:38 +0100 Received: from out1.ip08ir2.opaltelecom.net ([62.24.128.244]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1OlNJB-0007D8-G7 for rsgb_lf_group@blacksheep.org; Tue, 17 Aug 2010 15:38:38 +0100 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AvsEALQ7akxcEYl//2dsb2JhbACgPXGIJbgMhTcEgVaLCg X-IronPort-AV: E=Sophos;i="4.55,382,1278284400"; d="scan'208,217";a="458012526" Received: from unknown (HELO your91hoehfy9g) ([92.17.137.127]) by out1.ip08ir2.opaltelecom.net with SMTP; 17 Aug 2010 15:38:25 +0100 Message-ID: <005601cb3e19$dbc16420$0301a8c0@your91hoehfy9g> From: "mal hamilton" To: 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> <4C6A767E.3080103@iup.uni-heidelberg.de> Date: Tue, 17 Aug 2010 15:38:28 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: Earth electrodes antenna tests[Contest results] Content-Type: multipart/alternative; boundary="----=_NextPart_000_0053_01CB3E22.3D5D5C90" 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: 3039ac1d40064c6a9f362cf0 X-AOL-IP: 193.82.116.20 X-AOL-SPF: domain : blacksheep.org SPF : none ------=_NextPart_000_0053_01CB3E22.3D5D5C90 Content-Type: text/plain; charset="ISO-8859-15" Content-Transfer-Encoding: quoted-printable Stefan Are u using an audio amp, if so do u have a capacitor in series with= the link winding otherwise the winding might appear as an almost shor= t cct because of the low dc resistance. 73 de mal/g3kev ----- Original Message -----=20 From: Stefan Sch=E4fer=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Tuesday, August 17, 2010 12:46 PM Subject: Re: LF: Earth electrodes antenna tests[Contest results] 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 wi= nding just above the amperemeter. 73, Stefan Am 17.08.2010 13:38, schrieb mal hamilton:=20 Stefan I am talking about matching the amp 8 ohms to 50 ohms not about re= sonating the antenna. My antenna is already resonated for 9 Kcs, or 13= 7 as required. I was referring to your kite antenna and what method you used for= matching amp to antenna. de mal/g3kev ----- Original Message -----=20 From: Stefan Sch=E4fer=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Tuesday, August 17, 2010 12:22 PM Subject: Re: LF: Earth electrodes antenna tests[Contest results] Mal,=20 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 gener= ate a signal that can be watched in the far field.=20 And if you want to generate a signal that can be heared in CW ac= ross 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 suitabl= e for the audio amp (4...8 Ohm). A 50 Ohm impedance level is just nece= ssary 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 ante= nna! ;-) 73, Stefan PS: On an earth antenna, which is not resonated (!), you just ha= ve 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:=20 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 =20 ------=_NextPart_000_0053_01CB3E22.3D5D5C90 Content-Type: text/html; charset="ISO-8859-15" Content-Transfer-Encoding: quoted-printable
Stefan
Are u using an audio amp, if so do u= have a=20 capacitor in series with the link winding otherwise the winding might= appear as=20 an almost short cct because of the low dc resistance.
73 de mal/g3kev
 
----- Original Message -----
Sent: Tuesday, August 17, 201= 0 12:46=20 PM
Subject: Re: LF: Earth electr= odes antenna=20 tests[Contest results]

Mal,

I am using a galvanic decoupled primary= winding at=20 the bottom of the water barrel where the coil is wound on. Adjust th= e primary=20 number of turns so that enough power is fed into the system. Watch= the photo=20 on my qrz.com page named "new amperemeter". There you see the primar= y winding=20 just above the amperemeter.

73, Stefan


Am 17.08.20= 10 13:38,=20 schrieb mal hamilton:=20
Stefan
I am talking about matching the= amp 8 ohms to=20 50 ohms not about resonating the antenna. My antenna is already re= sonated=20 for 9 Kcs, or 137 as required.
I was referring to your kite ante= nna and what=20 method you used for matching amp to antenna.
de mal/g3kev
 
-----=20 Original Message -----
Sent:=20 Tuesday, August 17, 2010 12:22 PM
Subject:=20 Re: LF: Earth electrodes antenna tests[Contest results]

Mal,

Are you talking about a earth electr= ode=20 antenna or your vertical antenna? I assume you mean the vertical= =20 ;-)

You will get several kV, most probably above 10 kV rm= s on your=20 antenna. That's why a ferrite transformer is not a good choice= for a large=20 ( C ) antenna in addition with QRO! For your 5 W tests it may wo= rk with a=20 ferrite coil L but not at 500 W and above.

There is no= =20 alternative to wind an air coil if you want to generate a signal= that can=20 be watched in the far field.

And if you want to generate= a signal=20 that can be heared in CW across EU i recommend a power supply li= ke i had=20 as i worked in Darmstadt last year: http://www.hst.tu-darmsta= dt.de/index.php?id=3D173&L=3D1=20 ;-)

Transforming to 50 Ohm is not wrong but it is not nec= essary.=20 You can just resonate the antenna and match the load to somethin= g suitable=20 for the audio amp (4...8 Ohm). A 50 Ohm impedance level is just= necessary=20 if you want to filter your signal with a precise dimensioned low= pass=20 filter that properly works at 50 Ohm input and output impedance= (in my=20 opinion). Essential is, that the power is pushed into the antenn= a!=20 ;-)

73, Stefan

PS: On an earth antenna, which is= not=20 resonated (!), you just have to apply a proper output voltage to= the=20 antenna that causes the DC input power at the PA that you want= to=20 generate.


Am 17.08.2010 12:51, schrieb mal hamilton:= =20 
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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