Return-Path: Received: from mtain-dj08.r1000.mx.aol.com (mtain-dj08.r1000.mail.aol.com [172.19.187.144]) by air-di03.mail.aol.com (v129.4) with ESMTP id MAILINDI031-eabe4c78e93a256; Sat, 28 Aug 2010 06:47:22 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-dj08.r1000.mx.aol.com (Internet Inbound) with ESMTP id 76552380000B1; Sat, 28 Aug 2010 06:47:20 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OpIuw-0001Mx-Kj for rs_out_1@blacksheep.org; Sat, 28 Aug 2010 11:45:46 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OpIuv-0001Mo-PG for rsgb_lf_group@blacksheep.org; Sat, 28 Aug 2010 11:45:45 +0100 Received: from imr-ma06.mx.aol.com ([64.12.78.142]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1OpIuu-0005Y0-3k for rsgb_lf_group@blacksheep.org; Sat, 28 Aug 2010 11:45:45 +0100 Received: from mtaout-db02.r1000.mx.aol.com (mtaout-db02.r1000.mx.aol.com [172.29.51.194]) by imr-ma06.mx.aol.com (8.14.1/8.14.1) with ESMTP id o7SAjaMw027940 for ; Sat, 28 Aug 2010 06:45:36 -0400 Received: from Black (nrbg-4d07424c.pool.mediaWays.net [77.7.66.76]) by mtaout-db02.r1000.mx.aol.com (MUA/Third Party Client Interface) with ESMTPA id CE3AFE000086 for ; Sat, 28 Aug 2010 06:45:35 -0400 (EDT) Message-ID: <0B537E764BCB476F8F0CC7168686E14D@Black> From: "Markus Vester" To: References: , <4C77BCB1.4060608@iup.uni-heidelberg.de> In-Reply-To: <4C77BCB1.4060608@iup.uni-heidelberg.de> Date: Sat, 28 Aug 2010 12:45:29 +0200 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Windows Mail 6.0.6000.16480 X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6000.16669 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: VLF: Re: Transmitting 250W at 8970 Hz on a 600m spaced earth antenna Content-Type: multipart/alternative; boundary="----=_NextPart_000_0018_01CB46AE.E576C0D0" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.1 required=5.0 tests=HTML_MESSAGE, MISSING_OUTLOOK_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: 3039cdbc9d0d4c78e9380381 X-AOL-IP: 193.82.116.20 X-AOL-SPF: domain : blacksheep.org SPF : none ------=_NextPart_000_0018_01CB46AE.E576C0D0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Since 10:25, Stefan is on air again with his ground loop. Signals on= his own grabber are even better than yesterday, perhaps due to somewh= at lower QRN. I am also looking here but don't have much hope, as the= TX antenna is N-S oriented and Nuernberg is 180 km due east. Good luck, Markus (DF6NM) ----- Original Message -----=20 From: Stefan Sch=E4fer=20 To: rsgb_lf_group@blacksheep.org ; Renato Romero ; Paul ; Bernd Grup= e=20 Sent: Friday, August 27, 2010 3:25 PM Subject: VLF: Transmitting 250W at 8970 Hz on a 600m spaced earth an= tenna Dear VLF,=20 Today i spent some hours to do the next experiment with my earth ele= ctrode antenna that i have installed in a forest near Heidelberg. The= 2 earth electrodes are about 600 m spaced, with 20 copper earth rods= at each end. Location is 49.44894N_8.724619E. The todays goal is to reach the RX of Michael Oexner in about 50 km= distance at 8970 Hz. He is one of those who successfully copied my si= gnal on my 2nd VLF experiment, 15th, March (> 70 km distance). Today= he started running his PC using the soundcard and SpecLab as the RX.= His antenna is a PA0RDT design. He is still at work, so i am awaiting= his report with interest;-) It would be a new distance record on VLF= with earth electrode antennas. The day appeared reasonably suitable in the morning hours. Although= there was some rain, the QRN was down to -90 dB on my DFCW-600 window= on the VLF grabber (http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7= FC_VLF_Grabber.html), just about the level as in my last test. The las= t test was done with the 300 m antenna and about 70 W. There, the sign= al was about 10 dB above noise on my grabber in 5.0 km distance. A sum= mary of that can be found on rogers site: http://g3xbm-qrp.blogspot.co= m/2010/06/live-897khz-transmission-from-germany.html . Today i transmi= tted about 0,2 Hz lower since DF6NM also tried to copy the signal and= he has currently some noise at 8970.0 Hz. Today i used the SMPS, generator and the small PA (300 W), running= at 250 W. Sadly i had forgotten my amperemeter for the antenna curren= t and so the power was just measurable at the DC side of the PA, takin= g about 20 A at 13,8 V DC. The first attempt was arround 8:30...9:00= UTC (still visible on my grabber) but i didn't get the power into the= antenna (means too high Z), so there was something wrong with it. I= found that the electrode connections were disconnected, most probably= done by some animals. They even tried to grup out some earth rods ;-)= So in the first attempt the antenna was rather a lossy inv L antenna.= When applying about 400 V rms (not kV :-) ) to this inv L antenna, th= e signal was about 10 dB above ground anyway (pic1.jpg). After solving= that problem the antenna acted like a loop again. Sadly a storm and heavy rain came up during the experiment. I couldn= 't hear and thunder so i thought it is a normal rain. But there must= have been some charged clouds and charged raindrops falling down sinc= e later i found heavy white vertical lines on the grabber like is is= usual during thunder storms. This kind of "noise" appears rapidly and= goes rapidly, often the noise level increases and decreases by severa= l 10 dB during just some seconds. So it was a pity that this happend= just during the test. Maybe the situation at Micheal Oexner's QTH is= totally different! Compared to the last test, the TX power was 6 dB higher and the ante= nna has twice the length. The gain due to the increased size was measu= red to be 8 dB (RX level difference of DHO-38). But, the signal was 30= dB above noise in 4,5 mHz ( pic2.jpg), (DFCW-600 window) although the= noise was about 5 dB higher than in the last experiment (see Rogers= picture on his site). So, there is another 11 dB gain (35dB -(10dB+6d= B+8dB)). The radiation direction of the antenna and distance didn't ch= ange significantly so where does this gain come from?! I suppose it is= the wet soil that decreases the earth resistance near the earth elect= rodes! If this mountain/hill is mostly out of stone, the inner conduct= ivity does not change too strong but the electrode resistance seems to= do!? So, i mean, a wet soil is an advantage, not a disadvantege, as= long as the overall soil is not wet but just the upper layer. What do= the experts mean? :-) BTW, i have never seen people looking so astonished, seeing this gen= erator running in the middle of the forest on a rainy friday morning! Since it is a first test for a new distance record i transmitted jus= t a 30 minutes carrier, not a message. It would have been easy sending= a message to my grabber since the signal was VERY clearly readable,= even in DFCW-60 (pic3.jpg) the signal was up to 25 dB above noise. Mo= st unexpected, it was even readable in DFCW-3 (!), 10...15 dB above no= ise! (pic4.jpg) :-) So, hopefully Micheal will tell us some news this evening. If not po= sitive, we will go on. It was a first attempt at that distance and the= conds were really not perfect. Additionally there is a loss of about= 2 dB if the antenna acts like a loop. Markus/DF6NM received nothing= but if the antenna acts like a loop, it has it's minimum into Markus'= direction, sadly. Marco/DD7PC is in 60km distance and pretty exact in= the radiation maximum of the antenna, so he could become another RX= station? :-) Lastly, a picture of the impressing foggy forest like it was during= this experiment (pic5.jpg) :-)=20 73, Stefan/DK7FC ------=_NextPart_000_0018_01CB46AE.E576C0D0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Since 10:25, Stefan is on air again= with his ground=20 loop. Signals on his own grabber are even better than yesterday, perha= ps due to=20 somewhat lower QRN. I am also looking here but don't have much ho= pe,=20 as the TX antenna is N-S oriented and Nuernberg is 180 km du= e=20 east.
 
Good luck,
Markus (DF6NM)
 
----- Original Message -----
Sent: Friday, August 27, 2010= 3:25=20 PM
Subject: VLF: Transmitting 25= 0W at 8970=20 Hz on a 600m spaced earth antenna

Dear VLF,

Today i spent some hours to do the= next=20 experiment with my earth electrode antenna that i have installed in= a forest=20 near Heidelberg. The 2 earth electrodes are about 600 m spaced, with= 20 copper=20 earth rods at each end. Location is 49.44894N_8.724619E.

The= todays=20 goal is to reach the RX of Michael Oexner in about 50 km distance at= 8970 Hz.=20 He is one of those who successfully copied my signal on my 2nd VLF= experiment,=20 15th, March (> 70 km distance). Today he started running his PC= using the=20 soundcard and SpecLab as the RX. His antenna is a PA0RDT design. He= is still=20 at work, so i am awaiting his report with interest;-) It would be a= new=20 distance record on VLF with earth electrode antennas.

The day= appeared=20 reasonably suitable in the morning hours. Although there was some ra= in, the=20 QRN was down to -90 dB on my DFCW-600 window on the VLF grabber (http://www.iup.uni-heid= elberg.de/schaefer_vlf/DK7FC_VLF_Grabber.html),=20 just about the level as in my last test. The last test was done with= the 300 m=20 antenna and about 70 W. There, the signal was about 10 dB above nois= e on my=20 grabber in 5.0 km distance. A summary of that can be found on rogers= site: ht= tp://g3xbm-qrp.blogspot.com/2010/06/live-897khz-transmission-from-germ= any.html=20 . Today i transmitted about 0,2 Hz lower since DF6NM also tried to= copy the=20 signal and he has currently some noise at 8970.0 Hz.

Today i= used the=20 SMPS, generator and the small PA (300 W), running at 250 W.= Sadly i had=20 forgotten my amperemeter for the antenna current and so the power wa= s just=20 measurable at the DC side of the PA, taking about 20 A at 13,8 V DC.= The first=20 attempt was arround 8:30...9:00 UTC (still visible on my grabber) bu= t i didn't=20 get the power into the antenna (means too high Z), so there was some= thing=20 wrong with it. I found that the electrode connections were disconnec= ted, most=20 probably done by some animals. They even tried to grup out some eart= h rods ;-)=20 So in the first attempt the antenna was rather a lossy inv L antenna= . When=20 applying about 400 V rms (not kV :-) ) to this inv L antenna, the si= gnal was=20 about 10 dB above ground anyway (pic1.jpg). After solving that probl= em the=20 antenna acted like a loop again.

Sadly a storm and heavy rain= came up=20 during the experiment. I couldn't hear and thunder so i thought it= is a normal=20 rain. But there must have been some charged clouds and charged raind= rops=20 falling down since later i found heavy white vertical lines on the= grabber=20 like is is usual during thunder storms. This kind of "noise" appears= rapidly=20 and goes rapidly, often the noise level increases and decreases by= several 10=20 dB during just some seconds. So it was a pity that this happend just= during=20 the test. Maybe the situation at Micheal Oexner's QTH is totally=20 different!

Compared to the last test, the TX power was 6 dB= higher and=20 the antenna has twice the length. The gain due to the increased size= was=20 measured to be 8 dB (RX level difference of DHO-38). But, the sig= nal was 30=20 dB above noise in 4,5 mHz ( pic2.jpg), (DFCW-600 window) althoug= h the=20 noise was about 5 dB higher than in the last experiment (see Rogers= picture on=20 his site). So, there is another 11 dB gain (35dB -(10dB+6dB+8= dB)). The=20 radiation direction of the antenna and distance didn't change signif= icantly so=20 where does this gain come from?! I suppose it is the wet soil= that=20 decreases the earth resistance near the earth electrodes! If this=20 mountain/hill is mostly out of stone, the inner conductivity does no= t change=20 too strong but the electrode resistance seems to do!? So, i mean, a= wet=20 soil is an advantage, not a disadvantege, as long as the overall= soil is=20 not wet but just the upper layer. What do the experts mean? :-)
<= BR>BTW, i=20 have never seen people looking so astonished, seeing this generator= running in=20 the middle of the forest on a rainy friday morning!

Since it= is a first=20 test for a new distance record i transmitted just a 30 minutes carri= er, not a=20 message. It would have been easy sending a message to my grabber sin= ce the=20 signal was VERY clearly readable, even in DFCW-60 (pic3.jpg)= the signal=20 was up to 25 dB above noise. Most unexpected, it was even readable= in=20 DFCW-3 (!), 10...15 dB above noise! (pic4.jpg) :-)

So,= hopefully=20 Micheal will tell us some news this evening. If not positive, we wil= l go on.=20 It was a first attempt at that distance and the conds were really no= t perfect.=20 Additionally there is a loss of about 2 dB if the antenna acts like= a loop.=20 Markus/DF6NM received nothing but if the antenna acts like a loop,= it has it's=20 minimum into Markus' direction, sadly. Marco/DD7PC is in 60km distan= ce and=20 pretty exact in the radiation maximum of the antenna, so he could be= come=20 another RX station? :-)

Lastly, a picture of the impressing= foggy=20 forest like it was during this experiment (pic5.jpg) :-)

73,= =20 Stefan/DK7FC




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