Return-Path: Received: from mtain-mb05.r1000.mx.aol.com (mtain-mb05.r1000.mx.aol.com [172.29.96.25]) by air-dc05.mail.aol.com (v129.4) with ESMTP id MAILINDC053-86514be91994235; Tue, 11 May 2010 04:47:16 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-mb05.r1000.mx.aol.com (Internet Inbound) with ESMTP id BB4CF380000A0; Tue, 11 May 2010 04:47:14 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OBl5m-0002B3-0y for rs_out_1@blacksheep.org; Tue, 11 May 2010 09:45:30 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OBl5l-0002Au-DH for rsgb_lf_group@blacksheep.org; Tue, 11 May 2010 09:45:29 +0100 Received: from fmmailgate07.web.de ([217.72.192.248]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1OBl5h-0003jL-En for rsgb_lf_group@blacksheep.org; Tue, 11 May 2010 09:45:29 +0100 Received: from mwmweb079 ( [172.20.18.97]) by fmmailgate07.web.de (Postfix) with ESMTP id BC2EB1262CB for ; Tue, 11 May 2010 10:45:19 +0200 (CEST) Received: from [84.63.114.217] by mwmweb079 with HTTP; Tue May 11 10:45:19 CEST 2010 Message-ID: <25942409.3791470.1273567519765.JavaMail.fmail@mwmweb079> Date: Tue, 11 May 2010 10:45:19 +0200 (CEST) From: =?ISO-8859-15?Q?Horst_St=F6cker?= MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: , <4BE855F1.9050909@iup.uni-heidelberg.de> In-Reply-To: <4BE855F1.9050909@iup.uni-heidelberg.de> X-UI-Message-Type: mail X-Priority: 3 Importance: normal Sensitivity: Normal X-Provags-ID: V01U2FsdGVkX19WKYdEuvvW2VkKw4iTPUYuGOtAC3jvlmJioB2s7O5pBTYfxbLOlQgQ MtDkIF0DjYej/jMCFhf9lZRBiNXEbmxwEu66qCQ2pSLqAddWNmdKRw== X-Spam-Score: 1.7 (+) X-Spam-Report: autolearn=disabled,HTML_FONT_LOW_CONTRAST=0.766,HTML_MESSAGE=0.001,HTML_MIME_NO_HTML_TAG=0.512,MAILTO_TO_SPAM_ADDR=0.276,MIME_HTML_ONLY=0.001,MIME_HTML_ONLY_MULTI=0,MPART_ALT_DIFF=0.137 Subject: Re: LF: RE: 8,97 kHz active antenna circuit and pictures Content-Type: multipart/alternative; boundary="------------070404010203070500040801" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: **** X-Spam-Status: No, hits=4.9 required=5.0 tests=HTML_60_70,HTML_MESSAGE, HTML_MIME_NO_HTML_TAG,MAILTO_TO_SPAM_ADDR,MIME_HTML_ONLY, MIME_HTML_ONLY_MULTI,PRIORITY_NO_NAME 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: 3039ac1d60194be919925e64 X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --------------070404010203070500040801 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-UI-ATTACHMENT-ID-POSTFIX: f521756a-6e64-41d5-8154-a516d4df59d4

Hello Stefan,

TV Transformer, interesting. I= think it should work well on lower distance. QRP on 9kHz, hi. I also had= this idea after my first tests on 9kHz. I wanted to test it but my few TV= transformers are DST and I think I will need a flyback. The flybacks are= common in the first generations of tv sets up to the seventies but hard= to get nowadays.

I am not sure if the hoizontal= antenna is the best solution. As we know in theory there are more ground= losses. But if this will be of any significant influence at this low freq= uencies?

I am looking foward to your tes= ts again.

BTW I am waiting for more motiv= ating weather conditions. I collected a few hundred meters of isolated mil= itary wire. After confectioning it I will have material for an earthbase= of about 800 to 1000 m. This will be tested as soon as possible.

Horst

Von: "Stefan Schäfer" <Stefan.Schaefer@iup.uni-heidelberg.d= e>
Gesendet: 10.05.2010 20:52:33
An: rsgb_lf_gr= oup@blacksheep.org
Betreff: Re: LF: RE: 8,97 kHz active antenn= a circuit and pictures

Hello Victor, LF,

It took a little bit to reply to your= answer. You have been absolutely right! DLF(153kHz) is here just some 10k= m away and the strong french LF broadcast station on 162kHz has caused the= nonlinear working of my first stage i assume. Yesterday i talked with Mar= kus/DF6NM and he gave me the very useful hint to add a C between drain and= gnd of the first stage (what forms a low pass with the drain R). Before= some minutes i added a 100nF capacitor, so the edge frequency should be= about 15kHz. Before that, i have looked on a second experimental active= E field antenna how it influences the gain on the dreamers band (almost= no difference). But see the S/N improvement NOW on my grabber (http://www.iup.uni-heidelberg.de/schaefer_v= lf/DK7FC_VLF_Grabber.html)! What a big difference!!! :-)))))
So= happy about that! :-)
Tnx to Markus and you, Victor!

73= , Stefan/DK7FC

PS: I have built a small TX antenna at my new= home QTH in Heidelberg. With a TV transformer and my 300W PA (running at= 15W DC input) i apply about 2kV rms on a 10m horizontal wire, about 3m ab= ove gnd. The distance to the grabber here is 1,1km. Hopefully i can see so= mething, at least in DFCW-600...

Am 28.04.20= 10 15:51, schrieb victor13@online.nl:

Hi Stefan,

looks nice but I suspect you = have some im problem in your first stage because off the strong line at= 9 KHz,Maby it's better to use a filter at the input....

73

Victor

-----Oorspronkelijk bericht-----
Van: Stefan Schäfer [mailto:owner-rsgb_lf_group@blac= ksheep.org]Namens Stefan Schäfer
Verzonden: wo= ensdag 28 april 2010 12:50
Aan: rsgb_lf_group@blacksh= eep.org
Onderwerp: VLF: 8,97 kHz active antenna circuit an= d pictures

Dear LF,

Daniele and others asked for the circuit of my ac= tive E field antenna that i am using for my grabber. Now i have created a= pdf file where you can find the circuit and a picture of the arrangement= and a spectrogram of the currently working circuit.

http://www= .iup.uni-heidelberg.de/schaefer_vlf/8,97kHz%20active%20E%20field%20antenna= %20by%20DK7FC.pdf

So, if you are interested or want to get= some ideas for your own circuit, take a look on it. I hope the link works= .

So, best 73 and maybe cu this evening there, dreamers.
=
Stefan/DK7FC

--------------070404010203070500040801--

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