Return-Path: X-Spam-DCC: paranoid 1233; Body=3 Fuz1=2 Fuz2=3 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,HTML_40_50, HTML_MESSAGE autolearn=unavailable version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id s8SG08Dt002967 for ; Sun, 28 Sep 2014 18:00:08 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1XYGps-0006Zo-Qr for rs_out_1@blacksheep.org; Sun, 28 Sep 2014 16:56:32 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1XYGps-0006Zf-Aj for rsgb_lf_group@blacksheep.org; Sun, 28 Sep 2014 16:56:32 +0100 Received: from omr-m1.mx.aol.com ([64.12.224.134]) by relay1.thorcom.net with esmtps (TLSv1:DHE-RSA-AES256-SHA:256) (Exim 4.82) (envelope-from ) id 1XYGpp-0002OE-Iu for rsgb_lf_group@blacksheep.org; Sun, 28 Sep 2014 16:56:31 +0100 Received: from mtaout-aaj01.mx.aol.com (mtaout-aaj01.mx.aol.com [172.27.3.205]) by omr-m1.mx.aol.com (Outbound Mail Relay) with ESMTP id 42216380000B3 for ; Sun, 28 Sep 2014 11:56:26 -0400 (EDT) Received: from White (unknown [95.91.239.181]) by mtaout-aaj01.mx.aol.com (MUA/Third Party Client Interface) with ESMTPA id C9F1B3800008C for ; Sun, 28 Sep 2014 11:56:22 -0400 (EDT) Message-ID: <1FEF5D3CDFAF4F5D9A31B0134D133FCF@White> From: "Markus Vester" To: References: <54281B0D.4040202@gmail.com> Date: Sun, 28 Sep 2014 17:56:34 +0200 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 12.0.1606 X-MimeOLE: Produced By Microsoft MimeOLE V12.0.1606 x-aol-global-disposition: G DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20140625; t=1411919786; bh=oc3LrkHyv66o6DhxqI7gTJtyfBEzWGcT6HoyP5AqEFs=; h=From:To:Subject:Message-ID:Date:MIME-Version:Content-Type; b=JetT050lPYO547vKBr0qK0dHKvhWBv4weSUscaNOWFHuAbQDb52kJbJ8grvRgRiHc gcbHOMC3ToDtyC8+V/FifPPPR09qhCt/EwpAt/V69yzAedffLCTHMZI0rGdFVXdlkz Rs097uXxvNWnZtsdfXnxhgkiKqeiUq0SHNkkI3CU= x-aol-sid: 3039ac1b03cd54282fa67a03 X-AOL-IP: 95.91.239.181 X-Scan-Signature: bc223f74149f392a7d9f3881f05f1e70 Subject: Re: LF: ZEVS RX ant question Content-Type: multipart/alternative; boundary="----=_NextPart_000_0014_01CFDB45.8ADBF110" 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-Scanned-By: MIMEDefang 2.56 on 10.1.3.10 Status: O X-Status: X-Keywords: X-UID: 522 Dies ist eine mehrteilige Nachricht im MIME-Format. ------=_NextPart_000_0014_01CFDB45.8ADBF110 Content-Type: text/plain; charset="ISO-8859-15" Content-Transfer-Encoding: quoted-printable Hi Stefan, here is the simple source follower circuit which picked up Zevs and = Schumann resonances: = http://df6nm.bplaced.net/VLF/ELF/source_follower.jpg . The browsable = directory http://df6nm.bplaced.net/VLF/ELF/ also contains some = spectrograms, an usr configuration, and a couple of wav files which were = sampled at 250 samples/sec. In a postprocessing step, the strong 16.7 Hz = harmonics have been notched out, and the wav file header has been = modified for replay at 60x speed. What then sounds like statics are = actually "Q-bursts", super strong lightning events which resonate = globally in the earth / ionosphere cavity. I also wonder why your low frequency range looks so noisy. I suspect = that you might still have the noise blanker activated, which would be = sheer poison! It will modulate itself onto the usually strong 50 Hz line = and also onto a possible DC offset, generating sidebands that will = splatter all over the ELF spectrum. My recipe was trying to keep = everything linear, with the local 16.7 Hz line only a few dB below = fullscale, and Zevs only about - 91 dB. Best 73, Markus (DF6NM) From: DK7FC=20 Sent: Sunday, September 28, 2014 4:28 PM To: rsgb_lf_group@blacksheep.org=20 Subject: LF: ZEVS RX ant question HI VLF,=20 Yesterday i tried again to receive ZEVS. I didn't know if it was on air = but gave it a try. Recorded about 2 hours of the VLF spectrum received = on my T antenna (i.e. E-field). I also used a source follower (J310) but = added a 3 stage RC filter in front of the gate. I thought i can afford = some pF against ground now with the relatively large antenna which must = have about 150 pF. I used this circuit: = https://dl.dropboxusercontent.com/u/19882028/VLF/ZEVS%20test%20ant.jpg But somehow the spectrum looks not as expected. While the MSKs are still = strong, there is much noise below 2 kHz and the sferics appear to be = quite weak. See: = https://dl.dropboxusercontent.com/u/19882028/VLF/Garden%20T%20antenna%20V= LF%201.png I remember from tests with a small active antenna for VLF, where i used = 100 MOhm resistors on the gate, that charged humidity caused much noise. = Could this be the same effect here?=20 Should i try to use a lower input impedance of the preamp?=20 Maybe you remember, there were certain transistors, several decades ago, = they were called bipolar transistors, NPN and PNP. Maybe i should try = one of them? :-) Advice is apprechiated. Where are the experts? 73, Stefan/DK7FC ------=_NextPart_000_0014_01CFDB45.8ADBF110 Content-Type: text/html; charset="ISO-8859-15" Content-Transfer-Encoding: quoted-printable
Hi Stefan,
 
here is the simple source follower = circuit which=20 picked up Zevs and Schumann resonances: http://df6n= m.bplaced.net/VLF/ELF/source_follower.jpg=20 . The browsable directory http://df6nm.bplaced.net/VLF/E= LF/=20 also contains some spectrograms, an usr configuration, and a couple = of wav=20 files which were sampled at 250 samples/sec. In a postprocessing = step, the=20 strong 16.7 Hz harmonics have been notched out, and the wav file header = has been=20 modified for replay at 60x speed. What then sounds like = statics=20 are actually "Q-bursts", super strong lightning events=20 which resonate globally in the earth / ionosphere = cavity.
 
I also wonder why your low = frequency=20 range looks so noisy. I suspect that you might still have the noise = blanker=20 activated, which would be sheer poison! It will modulate = itself onto=20 the usually strong 50 Hz line and also onto a possible DC=20 offset, generating sidebands that will splatter all over the = ELF=20 spectrum. My recipe was trying to keep everything linear, with = the=20 local 16.7 Hz line only a few dB below fullscale, and = Zevs only about=20 - 91 dB.
 
Best 73,
Markus (DF6NM)
 

From: DK7FC
Sent: Sunday, September 28, 2014 4:28 PM
Subject: LF: ZEVS RX ant question

HI VLF,

Yesterday i tried again to receive ZEVS. = I didn't=20 know if it was on air but gave it a try. Recorded about 2 hours of the = VLF=20 spectrum received on my T antenna (i.e. E-field). I also used a source = follower=20 (J310) but added a 3 stage RC filter in front of the gate. I thought i = can=20 afford some pF against ground now with the relatively large antenna = which must=20 have about 150 pF. I used this circuit: https://dl.dropboxusercontent.com/u/19882028/VLF/ZEVS%20test%20ant= .jpg

But=20 somehow the spectrum looks not as expected. While the MSKs are still = strong,=20 there is much noise below 2 kHz and the sferics appear to be quite weak. = See: https://dl.dropboxusercontent.com/u/19882028/VLF/Gard= en%20T%20antenna%20VLF%201.png

I=20 remember from tests with a small active antenna for VLF, where i used = 100 MOhm=20 resistors on the gate, that charged humidity caused much noise. =
Could=20 this be the same effect here?
Should i try to use a lower input = impedance of=20 the preamp?
Maybe you remember, there were certain transistors, = several=20 decades ago, they were called bipolar transistors, NPN and PNP. Maybe i = should=20 try one of them? :-)

 Advice is apprechiated. Where are the=20 experts?

73, Stefan/DK7FC
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