Return-Path: X-Spam-DCC: paranoid 1356; Body=2 Fuz1=2 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-0.5 required=5.0 tests=BAYES_00,HTML_30_40, HTML_MESSAGE,RATWARE_GECKO_BUILD autolearn=no 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 s9PLbAEC010346 for ; Sat, 25 Oct 2014 23:37:11 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Xi8xn-0006rW-0m for rs_out_1@blacksheep.org; Sat, 25 Oct 2014 22:33:31 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Xi8xm-0006rN-Cl for rsgb_lf_group@blacksheep.org; Sat, 25 Oct 2014 22:33:30 +0100 Received: from mail-lb0-f193.google.com ([209.85.217.193]) by relay1.thorcom.net with esmtps (TLSv1:RC4-SHA:128) (Exim 4.82) (envelope-from <73dk7fc@googlemail.com>) id 1Xi8xk-0006FL-3N for rsgb_lf_group@blacksheep.org; Sat, 25 Oct 2014 22:33:29 +0100 Received: by mail-lb0-f193.google.com with SMTP id l4so918986lbv.4 for ; Sat, 25 Oct 2014 14:33:27 -0700 (PDT) X-DKIM-Result: Domain=googlemail.com Result=Good and Known Domain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=20120113; h=from:message-id:date:user-agent:mime-version:to:subject:references :in-reply-to:content-type; bh=adTnTu617FEgNMhLYYrNAh7/RNSckFGdAO2MqQnNF2g=; b=v9DsCBPflpoz8OEDbehp9mXMITtwelI/9ViMYzxKHHiYvl0zNyXco7Uc6VxoQQEfV4 tcOAFLwvpOriNeD7E6vnk/+A40L+0rP87WW9nVv8KktaCZ2bezCCijgLOhry8S6sVaPC bjJBaLlQ8lCqz2fYtvHtG+1VfGE+Tl3nQTW6dpf6GhL9IC7MHz5Gpuc0XE+/WJfVLWLm dd++6pv6AA8zVibIm6wr1OKPkMaTGNDDBpvEePaKbh7Hsuo2WikELXmgPrXlNGC0b3n7 KUer/2cZIcyVMScVYYWbC4/Py2W0WijEgM6aybxn7aBCqMzAEyIGb8sCRBkixK9BDzPC 7uUg== X-Received: by 10.112.87.162 with SMTP id az2mr12970295lbb.15.1414272807063; Sat, 25 Oct 2014 14:33:27 -0700 (PDT) Received: from [129.206.22.206] (pc206.iup.uni-heidelberg.de. [129.206.22.206]) by mx.google.com with ESMTPSA id x1sm3277007laa.20.2014.10.25.14.33.25 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sat, 25 Oct 2014 14:33:26 -0700 (PDT) From: DK7FC <73dk7fc@googlemail.com> X-Google-Original-From: DK7FC <73dk7fc@gmail.com> Message-ID: <544C1724.6020605@gmail.com> Date: Sat, 25 Oct 2014 23:33:24 +0200 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: <621ECFC5FFD44C5989A1DA8C7DE6D149@AGB> <542DB6ED.1050101@psk31.plus.com> <0ED8E8831B5B4AF7B303B9D722D436B0@AGB> <542ED037.5020506@psk31.plus.com> <5431727C.3040406@psk31.plus.com> <54317AAA.90402@psk31.plus.com> <5431A0DB.80403@psk31.plus.com> <5431C102.6070007@gmail.com> <5431C1BC.3050208@gmail.com> <5431CB8A.4010407@virginbroadband.com.au> <5432FB8F.1030001@gmail.com> <543319A3.4030705@gmail.com> In-Reply-To: <543319A3.4030705@gmail.com> X-Scan-Signature: ed9dcf4545ec97a65e50af1597e81212 Subject: Re: LF: Re: Schumann in my garden, final circuit design Content-Type: multipart/alternative; boundary="------------060806060800070205070503" 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: 872 This is a multi-part message in MIME format. --------------060806060800070205070503 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Hi ELF friends, Just for those who are interested... I have now finished my modifications to the ELF RX / preamp design for a long wire (E field) antenna. This is the final schematic https://dl.dropboxusercontent.com/u/19882028/VLF/DK7FC%20ELF%20RX%20schematic.jpg. Despite the low frequency, it is improtant to use goos shielding in a metallic box. This is how it looks here: https://dl.dropboxusercontent.com/u/19882028/VLF/DK7FC%20ELF%20RX.jpg I've been in the garden today again and recorded the ELF spectrum (file: https://dl.dropboxusercontent.com/u/19882028/VLF/VLF%20Garten%20in%20T%20Antenne25102014_1st.WAV (584 MB)). Unfortunately ZEVS was off the air during that time but i got SNR of Schumann resonances again and very low man made noise and design noise. Spectrogram: https://dl.dropboxusercontent.com/u/19882028/VLF/Schumann%20resonances%20on%20final%20design.png Soon i will do another attempt to trynsmit in the ELF range to detect my signal in 2.4 km distance... 73, Stefan/DK7FC Am 07.10.2014 00:37, schrieb DK7FC: > Hi ELF friends, > > Now the circuit is in a box: > https://dl.dropboxusercontent.com/u/19882028/VLF/Living%20in%20a%20box.jpg > > I measured the resistance against ground (which should be infinity!) > with an old Rohde & Schwarz tube multimeter, maybe from the 1960s. It > can measure R up to 3 G Ohm. Positive results, no change of the > displayed R if i connect the D.U.T. > I think Ha-Jo DJ1ZB may know the multimeter from his early days :-) > Image: > https://dl.dropboxusercontent.com/u/19882028/VLF/cooperating%20generations%20of%20technique.jpg > > New measurements tomorrow... > > 73, Stefan/DK7FC > > > Am 06.10.2014 22:29, schrieb DK7FC: >> Hi Edgar, >> >> Of course you were right. >> I thought i don't need a completely shielded box because i am in the >> garden and there is no electricity. >> But, the gate of the FET is quasi-floating and there is always some >> stray-C between the antenna wire and that gate. >> Even 0.1 pF coupling C and 100 MOhm means a HPF cut off near 16 kHz >> !! I run a test, disconnecting the antenna from the preamp and placed >> the end of the wire in 0.2m distance. The SNR of DHO38 on 23.4 kHz >> was 30 dB, despite connected circuitry (diodes, filter, stray-C to >> ground). >> Now i will again move the circuit, into a shielded box :-) >> More results tomorrow. >> Nice stuff to play with! Still some warm autumn days here... >> >> 73, Stefan/DK7FC >> >> Am 06.10.2014 00:51, schrieb edgar: >>> Hi Stefan, >>> >>> I suggest that you cover the LPF and FET with a piece of tin to stop >>> any external signals entering the circuit after the LPF. >>> >>> A thin piece of metal from coffee tin or similar food container can >>> be bent in a U shape to cover the components and then soldered at a >>> few points to the copper ground plane. >>> >>> Just leave a small clearance holes at the ends for the wires to pass >>> through. >>> >>> Regards, Edgar >>> Moonah, Tasmania. >>> >>> --------------060806060800070205070503 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Hi ELF friends,

Just for those who are interested...
I have now finished my modifications to the ELF RX / preamp design for a long wire (E field) antenna. This is the final schematic https://dl.dropboxusercontent.com/u/19882028/VLF/DK7FC%20ELF%20RX%20schematic.jpg. Despite the low frequency, it is improtant to use goos shielding in a metallic box. This is how it looks here: https://dl.dropboxusercontent.com/u/19882028/VLF/DK7FC%20ELF%20RX.jpg

I've been in the garden today again and recorded the ELF spectrum (file: https://dl.dropboxusercontent.com/u/19882028/VLF/VLF%20Garten%20in%20T%20Antenne25102014_1st.WAV (584 MB)). Unfortunately ZEVS was off the air during that time but i got SNR of  Schumann resonances again and very low man made noise and design noise. Spectrogram: https://dl.dropboxusercontent.com/u/19882028/VLF/Schumann%20resonances%20on%20final%20design.png

Soon i will do another attempt to trynsmit in the ELF range to detect my signal in 2.4 km distance...

73, Stefan/DK7FC







Am 07.10.2014 00:37, schrieb DK7FC:
Hi ELF friends,

Now the circuit is in a box: https://dl.dropboxusercontent.com/u/19882028/VLF/Living%20in%20a%20box.jpg

I measured the resistance against ground (which should be infinity!) with an old Rohde & Schwarz tube multimeter, maybe from the 1960s. It can measure R up to 3 G Ohm.  Positive results, no change of the displayed R if i connect the D.U.T.
I think Ha-Jo DJ1ZB may know the multimeter from his early days :-) Image: https://dl.dropboxusercontent.com/u/19882028/VLF/cooperating%20generations%20of%20technique.jpg

New measurements tomorrow...

73, Stefan/DK7FC


Am 06.10.2014 22:29, schrieb DK7FC:
Hi Edgar,

Of course you were right.
I thought i don't need a completely shielded box because i am in the garden and there is no electricity.
But, the gate of the FET is quasi-floating and there is always some stray-C between the antenna wire and that gate.
Even 0.1 pF coupling C and 100 MOhm means a HPF cut off near 16 kHz !! I run a test, disconnecting the antenna from the preamp and placed the end of the wire in 0.2m distance. The SNR of DHO38 on 23.4 kHz was 30 dB, despite connected circuitry (diodes, filter, stray-C to ground).
Now i will again move the circuit, into a shielded box :-)
More results tomorrow.
Nice stuff to play with! Still some warm autumn days here...

73, Stefan/DK7FC

Am 06.10.2014 00:51, schrieb edgar:
Hi Stefan,

I suggest that you cover the LPF and FET with a piece of tin to stop any external signals entering the circuit after the LPF.

A thin piece of metal from coffee tin or similar food container can be bent in a U shape to cover the components and then soldered at a few points to the copper ground plane.

Just leave a small clearance holes at the ends for the wires to pass through.

Regards, Edgar
Moonah, Tasmania.
--------------060806060800070205070503--