Return-Path: Received: from mtain-de11.r1000.mx.aol.com (mtain-de11.r1000.mx.aol.com [172.29.64.211]) by air-mc03.mail.aol.com (v129.4) with ESMTP id MAILINMC032-a8dc4c6a74f5d; Tue, 17 Aug 2010 07:39:33 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-de11.r1000.mx.aol.com (Internet Inbound) with ESMTP id 7E5BC380000A3; Tue, 17 Aug 2010 07:39:31 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OlKV0-00030V-Qn for rs_out_1@blacksheep.org; Tue, 17 Aug 2010 12:38:34 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OlKV0-00030M-Ab for rsgb_lf_group@blacksheep.org; Tue, 17 Aug 2010 12:38:34 +0100 Received: from out1.ip04ir2.opaltelecom.net ([62.24.128.240]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1OlKUz-0006GS-Dd for rsgb_lf_group@blacksheep.org; Tue, 17 Aug 2010 12:38:34 +0100 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AhAFALIRakxcEYdJ/2dsb2JhbACPT5BtcYgltH+FNwSBVosK X-IronPort-AV: E=Sophos;i="4.55,381,1278284400"; d="scan'208,217";a="301903683" Received: from unknown (HELO your91hoehfy9g) ([92.17.135.73]) by out1.ip04ir2.opaltelecom.net with SMTP; 17 Aug 2010 12:38:26 +0100 Message-ID: <003e01cb3e00$b7865f70$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> Date: Tue, 17 Aug 2010 12:38:30 +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_003B_01CB3E09.191FE6E0" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_20_30,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: 3039ac1d40d34c6a74f3274e X-AOL-IP: 193.82.116.20 X-AOL-SPF: domain : blacksheep.org SPF : none ------=_NextPart_000_003B_01CB3E09.191FE6E0 Content-Type: text/plain; charset="ISO-8859-15" Content-Transfer-Encoding: quoted-printable Stefan I am talking about matching the amp 8 ohms to 50 ohms not about resona= ting the antenna. My antenna is already resonated for 9 Kcs, or 137 as= required. I was referring to your kite antenna and what method you used for matc= hing 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 ant= enna? I assume you mean the vertical ;-) You will get several kV, most probably above 10 kV rms on your anten= na. 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 wi= th 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.=20 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 las= t 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 fo= r the audio amp (4...8 Ohm). A 50 Ohm impedance level is just necessar= y if you want to filter your signal with a precise dimensioned low pas= s 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 in= put 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_003B_01CB3E09.191FE6E0 Content-Type: text/html; charset="ISO-8859-15" Content-Transfer-Encoding: quoted-printable
Stefan
I am talking about matching the amp= 8 ohms to 50=20 ohms not about resonating the antenna. My antenna is already resonated= for 9=20 Kcs, or 137 as required.
I was referring to your kite antenna= and what=20 method you used for matching amp to antenna.
de mal/g3kev
 
----- Original Message -----
Sent: Tuesday, August 17, 201= 0 12:22=20 PM
Subject: Re: LF: Earth electr= odes antenna=20 tests[Contest results]

Mal,

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

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

There is no alternative to wind an air co= il if you=20 want to generate a signal that can be watched in the far field.
=
And if=20 you want to generate a signal that can be heared in CW across EU i= recommend a=20 power supply like i had as i worked in Darmstadt last year: http://www.hst.tu-darmstadt.de/index= .php?id=3D173&L=3D1=20 ;-)

Transforming to 50 Ohm is not wrong but it is not necessa= ry. You=20 can just resonate the antenna and match the load to something suitab= le for the=20 audio amp (4...8 Ohm). A 50 Ohm impedance level is just necessary if= you want=20 to filter your signal with a precise dimensioned low pass filter tha= t properly=20 works at 50 Ohm input and output impedance (in my opinion). Essentia= l is, that=20 the power is pushed into the antenna! ;-)

73, Stefan

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


Am 17.08.2010 12:51, schrieb mal ha= milton:=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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