Return-Path: X-Spam-DCC: paranoid 1170; 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=-0.8 required=5.0 tests=BAYES_00,HTML_50_60, 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 s93KJbGs030317 for ; Fri, 3 Oct 2014 22:19:37 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Xa9HH-0007gO-1A for rs_out_1@blacksheep.org; Fri, 03 Oct 2014 21:16:35 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Xa9HG-0007gF-Kb for rsgb_lf_group@blacksheep.org; Fri, 03 Oct 2014 21:16:34 +0100 Received: from mout0.freenet.de ([195.4.92.90]) by relay1.thorcom.net with esmtps (TLSv1.2:DHE-RSA-AES256-GCM-SHA384:256) (Exim 4.82) (envelope-from ) id 1Xa9HE-00045Q-AS for rsgb_lf_group@blacksheep.org; Fri, 03 Oct 2014 21:16:33 +0100 Received: from [195.4.92.140] (helo=mjail0.freenet.de) by mout0.freenet.de with esmtpa (ID dl4yhf@freenet.de) (port 25) (Exim 4.82 #2) id 1Xa9HC-0004kW-Sp for rsgb_lf_group@blacksheep.org; Fri, 03 Oct 2014 22:16:30 +0200 Received: from localhost ([::1]:48756 helo=mjail0.freenet.de) by mjail0.freenet.de with esmtpa (ID dl4yhf@freenet.de) (Exim 4.82 #2) id 1Xa9HC-0004fR-Oq for rsgb_lf_group@blacksheep.org; Fri, 03 Oct 2014 22:16:30 +0200 Received: from mx11.freenet.de ([195.4.92.21]:55836) by mjail0.freenet.de with esmtpa (ID dl4yhf@freenet.de) (Exim 4.82 #2) id 1Xa9Eq-0003Pt-T9 for rsgb_lf_group@blacksheep.org; Fri, 03 Oct 2014 22:14:04 +0200 Received: from blfd-4db01938.pool.mediaways.net ([77.176.25.56]:4413 helo=[192.168.178.21]) by mx11.freenet.de with esmtpsa (ID dl4yhf@freenet.de) (TLSv1:DHE-RSA-CAMELLIA256-SHA:256) (port 465) (Exim 4.82 #2) id 1Xa9Eq-0000eQ-DE for rsgb_lf_group@blacksheep.org; Fri, 03 Oct 2014 22:14:04 +0200 Message-ID: <542F038A.1000804@freenet.de> Date: Fri, 03 Oct 2014 22:14:02 +0200 From: wolf_dl4yhf User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:17.0) Gecko/20130620 Thunderbird/17.0.7 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <54281B0D.4040202@gmail.com> <1FEF5D3CDFAF4F5D9A31B0134D133FCF@White> <54296984.7080607@gmail.com> <542EFB24.5010300@iup.uni-heidelberg.de> In-Reply-To: <542EFB24.5010300@iup.uni-heidelberg.de> X-Originated-At: 77.176.25.56!4413 X-Scan-Signature: 92b6515a4252c45136e975e6745a1e0d Subject: Re: LF: ZEVS RX ant question, now success Content-Type: multipart/alternative; boundary="------------020806040500050707030304" 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: 597 This is a multi-part message in MIME format. --------------020806040500050707030304 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 8bit Hi Stefan, The 82 Hz signal looks good... you may even catch a glimpse of "DX" from the US and their 60 Hz mains with that setup. It's several dB down on ZEVS but sometimes good copy here, on an active E-field probe out in the woods (far away from old PC monitors which sometimes operated near 60 Hz). 73, Wolf DL4YHF . Am 03.10.2014 21:38, schrieb Stefan Schäfer: > Hi VLF, > > This evening i received ZEVS for the first time in the garden :-) > > I used nearly the same circuit than in my email below. However, i > found that the J310 was damaged! Remembers me on the old discussion if > protecting diodes are necessary or not :-) But this is a large > antenna, compared to an active E probe like the PA0RDT-antenna... > Now i've replaced the JFET and added two 4148 protecting diodes on the > gate against ground and plus. > Reception looks much better now: > 0...24kHz: > https://dl.dropboxusercontent.com/u/19882028/VLF/wide_500msperdiv_732mHzFFT_garden3rd.png > 0...4 kHz: > https://dl.dropboxusercontent.com/u/19882028/VLF/0...4kHz_500msperdiv_732mHzFFT_garden3rd.png > 0...500 Hz: > https://dl.dropboxusercontent.com/u/19882028/VLF/0...500Hz_500msperdiv_732mHzFFT_garden3rd.png > ZEVS in 7.6 mHz, 40 sec scroll rate: > https://dl.dropboxusercontent.com/u/19882028/VLF/ZEVS_1st.png > > It looks like i need some more gain on the lower frequencies. Will > modify the circuit a bit... > > 73, Stefan/DK7FC > >>> >>> *From:* DK7FC >>> *Sent:* Sunday, September 28, 2014 4:28 PM >>> *To:* rsgb_lf_group@blacksheep.org >>> >>> *Subject:* LF: ZEVS RX ant question >>> >>> HI VLF, >>> >>> 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%20VLF%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? >>> Should i try to use a lower input impedance of the preamp? >>> 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 --------------020806040500050707030304 Content-Type: text/html; charset=ISO-8859-15 Content-Transfer-Encoding: 8bit
Hi Stefan,

The 82 Hz signal looks good... you may even catch a glimpse of "DX" from the US and their 60 Hz mains with that setup.
It's several dB down on ZEVS but sometimes good copy here, on an active E-field probe out in the woods (far away from old PC monitors which sometimes operated near 60 Hz).

73,
  Wolf  DL4YHF .

Am 03.10.2014 21:38, schrieb Stefan Schäfer:
Hi VLF,

This evening i received ZEVS for the first time in the garden :-)

I used nearly the same circuit than in my email below. However, i found that the J310 was damaged! Remembers me on the old discussion if protecting diodes are necessary or not :-) But this is a large antenna, compared to an active E probe like the PA0RDT-antenna...
Now i've replaced the JFET and added two 4148 protecting diodes on the gate against ground and plus.
Reception looks much better now:
0...24kHz: https://dl.dropboxusercontent.com/u/19882028/VLF/wide_500msperdiv_732mHzFFT_garden3rd.png
0...4 kHz: https://dl.dropboxusercontent.com/u/19882028/VLF/0...4kHz_500msperdiv_732mHzFFT_garden3rd.png
0...500 Hz: https://dl.dropboxusercontent.com/u/19882028/VLF/0...500Hz_500msperdiv_732mHzFFT_garden3rd.png
ZEVS in 7.6 mHz, 40 sec scroll rate: https://dl.dropboxusercontent.com/u/19882028/VLF/ZEVS_1st.png

It looks like i need some more gain on the lower frequencies. Will modify the circuit a bit...

73, Stefan/DK7FC


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 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%20VLF%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?
Should i try to use a lower input impedance of the preamp?
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

--------------020806040500050707030304--