Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mg06.r1000.mx.aol.com (Internet Inbound) with ESMTP id 5244138000092; Sat, 30 Jul 2011 10:08:01 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1QnABb-0004l6-Oy for rs_out_1@blacksheep.org; Sat, 30 Jul 2011 15:06:39 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1QnABa-0004kx-HE for rsgb_lf_group@blacksheep.org; Sat, 30 Jul 2011 15:06:38 +0100 Received: from out1.ip05ir2.opaltelecom.net ([62.24.128.241]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from <g3kevmal@talktalk.net>) id 1QnABX-0008NK-R2 for rsgb_lf_group@blacksheep.org; Sat, 30 Jul 2011 15:06:38 +0100 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AgsAADoPNE5Ok8IO/2dsb2JhbAA5CJQUg3oBD49DeIE7BQEBBQgBAQMNPAIPHQEBAwUCAQMRBAEBChcBDRQBBBoGFggGEwoBAgIBAQqHUwLAPIMngxsEglCEW5w1 X-IronPort-AV: E=Sophos;i="4.67,291,1309734000"; d="scan'208,217";a="349942984" Received: from host-78-147-194-14.as13285.net (HELO xphd97xgq27nyf) ([78.147.194.14]) by out1.ip05ir2.opaltelecom.net with SMTP; 30 Jul 2011 15:06:28 +0100 Message-ID: <001301cc4ec1$dc601200$0401a8c0@xphd97xgq27nyf> From: "mal hamilton" <g3kevmal@talktalk.net> To: <rsgb_lf_group@blacksheep.org> References: <44B95F8B497148E4ADFB54AC46CEAA38@White> Date: Sat, 30 Jul 2011 15:06:21 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: LF: Re: DF6NM kite attempt Content-Type: multipart/alternative; boundary="----=_NextPart_000_0010_01CC4ECA.3DBB7F00" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.0 required=5.0 tests=HTML_20_30,HTML_MESSAGE, HTML_TITLE_EMPTY 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-SCOLL-SCORE: 0:2:486551136:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d60ce4e34104052e0 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. ------=_NextPart_000_0010_01CC4ECA.3DBB7F00 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Markus Are u still transmitting? There was a strong trace around 1100 gmt de mal/g3kev ----- Original Message -----=20 From: Markus Vester=20 To: rsgb_lf_group@blacksheep.org=20 Cc: Paul ; Stefan Sch=E4fer=20 Sent: Saturday, July 30, 2011 8:52 AM Subject: VLF: DF6NM kite attempt Dear LF, today around noon, I will attempt another kite transmission from the = same site. If all works well, I will send a 1 mW carrier on 8970.002 = from around 11 to 14 UT. Best regards, Markus (DF6NM) From: Markus Vester=20 Sent: Tuesday, June 21, 2011 12:00 AM To: rsgb_lf_group@blacksheep.org=20 Subject: VLF: DF6NM kite activity June 19 Dear Dreamers, thanks very much to everyone who commented on my signal yesterday = night, and all who are running their VLF grabbers. Transmission: My signal was on air on 8970.002 Hz from 18:52 to 22:01, with a long = break from 19:26 to 19:52 due to a prolonged rain period, and many = shorter interruptions caused by precipitation, low wind, a coil falling = over, or a breaking antenna connection. I'm aware that an advanced notice would have been valuable for = potential receiving stations. But I find it difficult to plan ahead this = type of activity. Yesterday even while setting things up on the site, I = was not at all sure whether I would be able to actually get on air for = any significant time.=20 Site: The location (49.3874 N 11.1692 E, "JN59OJ02HX" for those who prefer = cryptic notations ;-) was the same as in the experiment on Nov 13 last = year (see email copy at bottom). While Google Maps still shows large = patches of unused land around the former US airfield, "my" field is now = one of very few undeveloped plots in the middle of an industrial area, = inhabited mostly by large logistics companies. Though I had originally = not intended to work into darkness, I found there was still plenty of = light from the surrounding truck parking and unloading areas. Kite antenna and ground: This time I used a 4 sqm lifter kite (HQ Power Sled L3.0, similar to = Stefan's smaller kite). It is held by a 150 m line. This may be = stretching the limit a bit, but due to the slope and sag of the line I = am sure that the peak altitude always stayed below 100 m. The previously used 0.4 mm magnet wire had a voltage limit of about 12 = kV due to corona appearing along the whole length. It has now been = replaced by insulated wire (0.25 sqmm, outer diameter 1.3 mm). The total = length is 180 m, with the last 30 m dangling down from the kite, = intended to act as a sort of extra top load. Effective height would be = around 50 m, giving 3.5 milliohm radiation resistance, or 1.3 mW EMRP at = 0.6 A. At the western end of the unused site, there is a long mesh wire fence = running north-south, held by solid metal posts which served very well = both for anchoring and grounding. Total resistance of the antenna = circuit was around 280 ohms (including 140 ohms for the coil). This is = about half of that when I used the same kite antenna in Bamberg with = only a few short ground pegs. The coil was placed below the kite line at about 3 m from the anchor = point, hoping to keep the wire well above ground. However this turned = out to be problematic due to the horizontal and vertical movement of the = connection point. When the kite was low and due west, the wire was too = long and touched the wet grass, exhibiting pretty little fireworks. When = it went up or drifted aside, the wire became too short, and either = plugged itself off, or tipped over the whole coil. You guess how much I = like having to reconnect the ungrounded wire, with dark clouds overhead = and a slight drizzle going down... I twice found myself holding down the = kite line with my foot, then slowly stepping forward until the open end = at least touched the earth. Next time I will definitely place the coil = much closer to the anchor, and try to hold the connection up by means of = some elastic plastic tube. Coil: From the previous experiment I knew that the wire capacitance was very = close to 900 pF. During the afternoon, I experimented with different = coil configurations, and found that I could either use four buckets (184 = ohms) with a large 10 cm pitch (ie. 9 Lego blocks), giving about 8 mm = radial clearance between one coil layer and the inner radius of the next = bucket. The other option was three buckets (138 ohms), stuffed into one = another 3 cm pitch and 2 mm clearance (see picture = http://df6nm.bplaced.net/VLF/pictures/two_coils_350mH.jpg). Mainly for mechanical reasons, I opted for the more compact = three-bucket solution, but this turned out to be the wrong choice. With = power applied, I heard corona sizzles around the coil at about 0.55 A = (11 kV). In darkness I could see violet seams near the bottom end of the = upper two windings. This means that the maximum usable layer-to-layer = voltage for this design is about 3.7 kV. Next time I will definitely go = for the longer version, which also has more surface exposed to the wind = for heat removal. BTW all seven buckets connected to 900 pF resonate at about 4.6 kHz - = Stefan, how about a 65 km band ;-) Amplifier and power supply: Like before, I used one channel of a class-B car-audio amp (Nitro = 3000), feeding a 12 : 80 turns ferrite transformer originally wound by = DJ2LF. It delivered 0.6 A antenna current (~ 100 W) from 12V x 13 A DC = input. It was possible to turn the volume up to 0.7A, but I did not dare = to run that level of corona permanently. The amp was fed by a standalone = 35 Ah lead-acid battery, which was repeatedly recharged via jumper wires = from the car engine during the latter half of the experiment. Signal generation: SpecLab's samplerate was locked to DHO, which is very slightly (3 ppb) = above its nominal frequency 23.4 kHz. To keep the average phase steady, = I took care to never interrupt the software generator whenever I had to = take the carrier off air. Anyway the time series recorded by Paul = Nicholson shows two major phase jumps around 19:40 (while the TX was = off) and 21:20, perhaps due to soundcard buffering issues. One problem I = did not see immediately was that the DHO ferrite antenna was too close = to one of the jumper wires, temporarily picking up interference when the = car alternator was running - once found, this one was easily fixed. Results: Though the traces at TF3HZ (2547 km) and YO/4X1RF (1253 km) are close = to the noise, they are at the right time and frequency, and I do not = think that they are random pixels. Halld=F3r's trace even seems to show = the outage period after the first bright dot.=20 On my own grabber, I attempted to compare signal levels from DK7FC = (-71 dB, 180 km) and myself (-43 dB, 4.5 km). Correcting this difference = (28 dB) by the EMRP ratio (26 mW / 1.2 mW =3D 13 dB), distance ratio = (1/r =3D 32 dB) plus an additional nearfield correction (1/r=B3 instead = of 1/r from 4.5 to 5.3 km =3D 3 dB), we find that Stefan was 28+13-35 dB = =3D 6 dB weaker than we would expect by pure groundwave. This = corresponds very well to the earlier experience that there is a midday = skywave cancellation effect for about 200 km.=20 Best wishes, Markus (DF6NM) From: Stefan Sch=E4fer=20 Sent: Monday, June 20, 2011 10:48 AM To: rsgb_lf_group@blacksheep.org=20 Subject: Re: VLF: DF6NM on 8970 Hz!! Fwd: Fwd: VLF: More food for = grabbers Hello Markus,=20 This was your strongest signal received here so far. Tell us about = your rig! Where did the TX power come from? A battery? Must have been a = big battery or you must have had very low losses. Transmitting during the night could be an interesting point. I could = try to use the 100m kite antenna on 8970 Hz as well. Then, no special = permit would be needed but my signal would be 10 dB lower. Anyway this = could be interesting. Or i could try night transmissions on the fixed = antenna.... Happy to see more activity here again! :) 73, Stefan/DK7FC ________________________________________ From: Markus Vester=20 Sent: Sunday, November 14, 2010 12:04 AM To: rsgb_lf_group@blacksheep.org=20 Cc: Paul=20 Subject: Re: VLF: TX on 6.47 and 8.97 Dear LF, Paul, here's a short summary of today's VLF kite transmission. I'm sorry for = the late notice, but the experiment had not been planned ahead, and I = wasn't sure if I could get on at all. Also, the kite I am using (a 0.8 = m^2 delta toy bought for 4.99 Euro) is a bit small for this sort of = activity, and really requires a good and steady wind. =20 The QTH was actually at 49.3874 N 11.1692 E, a few 100 meters from the = former location reported earlier. The GPS-controlled carriers were on = air=20 11:15 - 12:15 6470.000 Hz ~ 50 uW, and=20 12:30 - 13:10 8970.002 Hz ~ 200 uW (EMRP). Getting on 6470 was easier than expected. I simply used the same = "seven-bucket" coil, which resonates my 240 pF home antenna to 8.97 kHz. = Connected to the kite wire, the resonance was close enough to 6.5 kHz to = be tuned by the ferrite plate variometer. Then the drive for the audio = amp was increased until the onset of corona sizzling at 0.25 A. At that = point, the amp drew 10 A DC from the car battery and probably delivered = around 50 W. After connecting mobile internet and staring at Stefan's = grabber, I was positively surprised to find a faint trace there! For the frequency change, I removed the two bottom coil buckets, which = brought the resonance to ~ 8.5 kHz. Then I had to carefully pull the = remaining 5 buckets apart, inserting bits of plastic foam material as = spacers. Going through a few iterations took about 10 minutes, and I got = to "full power" (380 mA, 100W) at 12:30. Unfortunately, the wind had = started to calm by then, and there were several dips during this = transmission. Finally at 13:10, the kite landed gently in the grass, and = I decided to close down and pack up early. Traces from both transmissions were visible on DK7FC's 4.5 mHz "600" = windows, and the second one also produced a nice dash on the 0.45 mHz = window. It is likely that these signals would be useful for a = kite-to-kite QSO on either frequency, using 10 minute dashes. The screenshot from F1AFJ has an interesting dash before 13:00. The = indicated frequency seems a bit high (8970.020 instead of 8970.002), = which could perhaps be due to a small samplerate calibration error. I am = also not sure about the time scale - judging by the width of the noise = blobs, the setting could have been 11 mHz and 10 seconds per pixel. It = would be nice if Jean-Pierre could confirm the frequency calibration and = scroll settings. I also carefully inspected the OE3GHB grabber, which runs at 1.4 mHz = resolution and seems to be very sensitive. It showed an unusually dark = period of very low noise between 8 and 11 UT today. But no luck for my = transmission there yet. Well, in addition to the technical aspects, being outdoors in the warm = wind was again a rewarding and enjoyable experience.=20 Best 73, and thanks again for the interest.=20 Markus (DF6NM) ... ------=_NextPart_000_0010_01CC4ECA.3DBB7F00 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD><TITLE></TITLE> <META http-equiv=3DContent-Type = content=3Dtext/html;charset=3Diso-8859-1> <META content=3D"MSHTML 6.00.2600.0" name=3DGENERATOR> <STYLE></STYLE> </HEAD> <BODY id=3DMailContainerBody=20 style=3D"PADDING-RIGHT: 10px; PADDING-LEFT: 10px; PADDING-TOP: 15px" = text=3D#000000=20 bgColor=3D#ffffff leftMargin=3D0 topMargin=3D0 name=3D"Compose message = area"=20 CanvasTabStop=3D"true"> <DIV><FONT face=3DArial>Markus</FONT></DIV> <DIV><FONT face=3DArial>Are u still transmitting? There was a strong = trace around=20 1100 gmt</FONT></DIV> <DIV><FONT face=3DArial>de mal/g3kev</FONT></DIV> <DIV> </DIV> <BLOCKQUOTE dir=3Dltr=20 style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; = BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px"> <DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV> <DIV=20 style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: = black"><B>From:</B>=20 <A title=3Dmarkusvester@aol.com = href=3D"mailto:markusvester@aol.com">Markus=20 Vester</A> </DIV> <DIV style=3D"FONT: 10pt arial"><B>To:</B> <A = title=3Drsgb_lf_group@blacksheep.org=20 = href=3D"mailto:rsgb_lf_group@blacksheep.org">rsgb_lf_group@blacksheep.org= </A>=20 </DIV> <DIV style=3D"FONT: 10pt arial"><B>Cc:</B> <A = title=3Dpaul@abelian.netcom.co.uk=20 href=3D"mailto:paul@abelian.netcom.co.uk">Paul</A> ; <A=20 title=3DStefan.Schaefer@iup.uni-heidelberg.de=20 href=3D"mailto:Stefan.Schaefer@iup.uni-heidelberg.de">Stefan = Sch=E4fer</A> </DIV> <DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Saturday, July 30, 2011 = 8:52=20 AM</DIV> <DIV style=3D"FONT: 10pt arial"><B>Subject:</B> VLF: DF6NM kite = attempt</DIV> <DIV><BR></DIV> <DIV><FONT face=3DArial size=3D2>Dear LF,</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>today around noon, I will attempt = another=20 kite transmission from the same site. If all works well, I=20 will send a 1 mW carrier on 8970.002 from around = 11 to 14=20 UT.</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>Best regards,</FONT></DIV> <DIV><FONT face=3DArial size=3D2>Markus (DF6NM)</FONT></DIV> <DIV style=3D"FONT: 10pt Tahoma"> <DIV><FONT face=3DArial></FONT><FONT face=3DArial></FONT><FONT=20 face=3DArial></FONT><FONT face=3DArial></FONT><FONT = face=3DArial></FONT><FONT=20 face=3DArial></FONT><FONT face=3DArial></FONT><BR></DIV> <DIV style=3D"BACKGROUND: #f5f5f5"> <DIV style=3D"font-color: black"><B>From:</B> <A=20 title=3D"mailto:markusvester@aol.com STRG + Klicken, um = Verkn=FCpfung zu folgen"=20 href=3D"mailto:markusvester@aol.com">Markus Vester</A> = </DIV></DIV></DIV> <DIV style=3D"FONT: 10pt Tahoma"> <DIV style=3D"BACKGROUND: #f5f5f5"> <DIV><B>Sent:</B> Tuesday, June 21, 2011 12:00 AM</DIV> <DIV><B>To:</B> <A=20 title=3D"mailto:rsgb_lf_group@blacksheep.org STRG + Klicken, um = Verkn=FCpfung zu folgen"=20 = href=3D"mailto:rsgb_lf_group@blacksheep.org">rsgb_lf_group@blacksheep.org= </A>=20 </DIV> <DIV><B>Subject:</B> VLF: DF6NM kite activity June = 19</DIV></DIV></DIV> <DIV><FONT face=3DArial size=3D2></FONT><FONT face=3DArial = size=3D2></FONT><FONT=20 face=3DArial size=3D2></FONT><BR></DIV> <DIV><FONT face=3DArial><FONT size=3D2><FONT face=3DArial = size=3D2>Dear=20 Dreamers,</FONT></FONT></FONT></DIV> <DIV><FONT face=3DArial><FONT size=3D2><FONT face=3DArial=20 size=3D2></FONT></FONT></FONT> </DIV> <DIV><FONT face=3DArial><FONT size=3D2><FONT face=3DArial = size=3D2>thanks very much to=20 everyone who commented on my signal yesterday night, and all = who are running their VLF grabbers.</FONT></FONT></FONT></DIV> <DIV><FONT face=3DArial><FONT size=3D2><FONT face=3DArial=20 size=3D2></FONT></FONT></FONT> </DIV> <DIV><FONT face=3DArial><FONT size=3D2><FONT face=3DArial=20 size=3D2>Transmission:</FONT></FONT></FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial><FONT size=3D2><FONT face=3DArial size=3D2>My = signal was on=20 air on 8970.002 Hz from 18:52 to 22:01, with a long break from 19:26 = to 19:52=20 due to a prolonged rain period, and many shorter interruptions = caused by=20 precipitation, low wind, a coil falling over, or a breaking antenna=20 connection.</FONT></FONT></FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial><FONT size=3D2><FONT face=3DArial size=3D2>I'm = aware that an=20 advanced notice would have been valuable for = potential receiving=20 stations. But I find it difficult to plan ahead this = type=20 of activity. Yesterday even while setting things up on the site, = I was=20 not at all sure whether I would be able to actually get on air = for any=20 significant time. </FONT></FONT></FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>Site:</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>The location (49.3874 N 11.1692 = E,=20 "JN59OJ02HX" for those who prefer cryptic notations ;-) was = the=20 same as in the experiment on Nov 13 last year (see = email=20 copy at bottom). While Google Maps still shows large = patches of=20 unused land around the former US airfield, "my"=20 field is now one of very few undeveloped plots in = the=20 middle of an industrial area, inhabited mostly by large logistics = companies.=20 <FONT face=3DArial size=3D2>Though I had originally not = intended to work=20 into darkness, I found there was still plenty of light from = the=20 surrounding truck parking and unloading areas.</FONT></FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>Kite antenna and ground:</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>This time I used a 4 sqm = lifter kite=20 (HQ Power Sled L3.0, similar to Stefan's smaller kite). It is = held by a=20 150 m line. This may be stretching the limit a bit, but due to the = slope and=20 sag of the line I am sure that the peak altitude always = stayed=20 below 100 m.</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV><FONT face=3DArial = size=3D2> <DIV><FONT face=3DArial size=3D2>The previously used 0.4 mm = magnet=20 wire had a voltage limit of about 12 kV due to corona = appearing=20 along the whole length. It has now been replaced by insulated = wire (0.25=20 sqmm, outer diameter 1.3 mm). The total length is 180 m, with the = last 30=20 m dangling down from the kite, intended to act as a sort of extra top = load.=20 Effective height would be around 50 m, giving 3.5 milliohm radiation=20 resistance, or 1.3 mW EMRP at 0.6 A.</FONT></DIV> <DIV> </DIV> <DIV>At the western end of the unused site, there is a long mesh wire = fence=20 running north-south, held by solid metal posts=20 which served very well both for anchoring and grounding. = Total=20 resistance of the antenna circuit was around 280 ohms (including 140 = ohms for=20 the coil). This is about half of that when I used the same = kite=20 antenna in Bamberg with only a few short ground pegs.</DIV> <DIV></FONT> </DIV> <DIV><FONT face=3DArial size=3D2> <DIV>The coil was placed below the kite line at about 3 m from = the anchor=20 point, hoping to keep the wire well above ground. However this = turned out=20 to be problematic due to the horizontal and vertical movement of = the=20 connection point. When the kite was low and due west, = the wire was=20 too long and touched the wet grass, exhibiting pretty little = fireworks.=20 When it went up or drifted aside, the wire became too short, and = either=20 plugged itself off, or tipped over the whole coil. You guess how = much I=20 like having to reconnect the ungrounded wire, with dark clouds = overhead and a=20 slight drizzle going down... I twice found myself holding = down=20 the kite line with my foot, then slowly stepping forward until = the open=20 end at least touched the earth. Next time I will definitely = place=20 the coil much closer to the anchor, and try to hold = the connection=20 up by means of some elastic plastic tube.</DIV> <DIV> </DIV>Coil:</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>From the previous experiment I knew = that the wire=20 capacitance was very close to 900 pF. During the afternoon, I = experimented=20 with different coil configurations, and found that I could = either=20 use four buckets (184 ohms) with a large 10 = cm pitch=20 (ie. 9 Lego blocks), giving about 8 mm radial clearance = between one=20 coil layer and the inner radius of the next bucket. The = other=20 option was three buckets (138 ohms), stuffed into=20 one another 3 cm pitch and 2 mm clearance (see picture = <A=20 = title=3D"http://df6nm.bplaced.net/VLF/pictures/two_coils_350mH.jpg ST= RG + Klicken, um Verkn=FCpfung zu folgen"=20 = href=3D"http://df6nm.bplaced.net/VLF/pictures/two_coils_350mH.jpg">http:/= /df6nm.bplaced.net/VLF/pictures/two_coils_350mH.jpg</A>).</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>Mainly for mechanical reasons, I = opted for the=20 more compact three-bucket solution, but this turned out to = be the=20 wrong choice. With power applied, I heard = corona sizzles around=20 the coil at about 0.55 A (11 kV). In darkness I could = see violet=20 seams near the bottom end of the upper two windings. This means that = the=20 maximum usable layer-to-layer voltage for this design is = about 3.7 kV.=20 Next time I will definitely go for the longer version, which also = has=20 more surface exposed to the wind for heat removal.</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>BTW all seven buckets = connected to 900=20 pF resonate at about 4.6 kHz - Stefan, how about a 65 km = band=20 ;-)</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>Amplifier and </FONT><FONT = face=3DArial=20 size=3D2>power supply:</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>Like before, I used one channel=20 of a class-B car-audio amp (Nitro 3000), feeding a 12 : = 80=20 turns ferrite transformer originally wound by DJ2LF. It = delivered 0.6 A=20 antenna current (~ 100 W) from 12V x 13 A DC input. It = was=20 possible to turn the volume up to 0.7A, but I did=20 not dare to run that level of corona=20 permanently. The amp was fed by a standalone 35 Ah lead-acid = battery,=20 which was repeatedly recharged via jumper wires from = the car=20 engine during the latter half of the experiment.</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>Signal generation:</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>SpecLab's samplerate was locked = to DHO,=20 which is very slightly (3 ppb) above its nominal frequency = 23.4=20 kHz. To keep the average phase steady, I took care to never = interrupt the=20 software generator whenever I had to take the carrier off=20 air. Anyway t<FONT face=3DArial size=3D2>he time series = recorded by Paul=20 Nicholson shows two major phase jumps around 19:40 (while = the TX was=20 off) and 21:20, perhaps due to soundcard buffering = issues. </FONT>One=20 problem I did not see immediately was that the DHO ferrite antenna was = too=20 close to one of the jumper wires, temporarily picking up = interference=20 when the car alternator was running - once found, this one was = easily=20 fixed.</FONT></DIV> <DIV><FONT face=3DArial size=3D2> </DIV></FONT> <DIV><FONT face=3DArial size=3D2>Results:</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>Though the traces at TF3HZ (2547 km) = and YO/4X1RF=20 (1253 km) are close to the noise, they are at the right time and=20 frequency, and I do not think that they are random = pixels.=20 Halld=F3r's trace even seems to show the outage period after the first = bright=20 dot. </FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>On my own grabber, I attempted=20 to compare signal levels from DK7FC (-71 dB, 180 km) = and myself=20 (-43 dB, 4.5 km). Correcting this difference (28 dB) by the = EMRP=20 ratio (26 mW / 1.2 mW =3D 13 dB), distance ratio (1/r =3D 32=20 dB) plus an additional nearfield correction (1/r=B3 = instead of=20 1/r from 4.5 to 5.3 km =3D 3 dB), we find that Stefan = was</FONT><FONT=20 face=3DArial size=3D2> 28+13-35 dB =3D 6 dB weaker than we would = expect by pure=20 groundwave. This corresponds very well to the earlier experience that = there is=20 a midday skywave cancellation effect for about 200 = km. </FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT><FONT face=3DArial=20 size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>Best wishes,</FONT></DIV> <DIV><FONT face=3DArial size=3D2>Markus (DF6NM)</DIV></FONT> <DIV><FONT face=3DArial size=3D2> </DIV></FONT> <DIV style=3D"FONT: 10pt Tahoma; font-color: black"><FONT=20 face=3DArial><B>From:</B> </FONT><A=20 title=3D"mailto:schaefer@iup.uni-heidelberg.de STRG + Klicken, um = Verkn=FCpfung zu folgen"=20 href=3D"mailto:schaefer@iup.uni-heidelberg.de"><FONT=20 title=3D"mailto:schaefer@iup.uni-heidelberg.de STRG + Klicken, um = Verkn=FCpfung zu folgen"=20 face=3DArial>Stefan Sch=E4fer</FONT></A> </DIV> <DIV><FONT face=3DArial><FONT size=3D2><B>Sent:</B> Monday, June 20, = 2011 10:48=20 AM</FONT></FONT></DIV> <DIV><FONT face=3DArial><FONT size=3D2><B>To:</B> </FONT></FONT><A=20 title=3D"mailto:rsgb_lf_group@blacksheep.org STRG + Klicken, um = Verkn=FCpfung zu folgen"=20 href=3D"mailto:rsgb_lf_group@blacksheep.org"><FONT=20 title=3D"mailto:rsgb_lf_group@blacksheep.org STRG + Klicken, um = Verkn=FCpfung zu folgen"=20 face=3DArial size=3D2>rsgb_lf_group@blacksheep.org</FONT></A> </DIV> <DIV><FONT face=3DArial><FONT size=3D2><B>Subject:</B> Re: VLF: DF6NM = on 8970 Hz!!=20 Fwd: Fwd: VLF: More food for grabbers</FONT></FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT><FONT face=3DArial = size=3D2><BR></FONT></DIV> <DIV><FONT face=3DArial size=3D2>Hello Markus, <BR><BR>This was your = strongest=20 signal received here so far. Tell us about your rig! Where did the TX = power=20 come from? A battery? Must have been a big battery or you must have = had very=20 low losses.<BR><BR>Transmitting during the night could be an = interesting=20 point. I could try to use the 100m kite antenna on 8970 Hz as well. = Then, no=20 special permit would be needed but my signal would be 10 dB lower. = Anyway this=20 could be interesting. Or i could try night transmissions on the fixed=20 antenna....<BR><BR>Happy to see more activity here again! = :)<BR><BR>73,=20 Stefan/DK7FC</FONT></DIV> <DIV><FONT face=3DArial=20 size=3D2>________________________________________</FONT></DIV> <DIV><FONT face=3DArial><FONT size=3D2><FONT face=3DArial=20 size=3D2></FONT></FONT></FONT> </DIV> <DIV style=3D"font-color: black"><FONT face=3DArial><FONT = size=3D2><B>From:</B>=20 </FONT></FONT><A title=3Dmarkusvester@aol.com href=3D""><FONT = face=3DArial=20 size=3D2>Markus Vester</FONT></A> </DIV> <DIV><FONT face=3DArial><FONT size=3D2><B>Sent:</B> Sunday, November = 14, 2010=20 12:04 AM</FONT></FONT></DIV> <DIV><FONT face=3DArial><FONT size=3D2><B>To:</B> </FONT></FONT><A=20 title=3D"mailto:rsgb_lf_group@blacksheep.org STRG + Klicken, um = Verkn=FCpfung zu folgen"=20 href=3D""><FONT face=3DArial = size=3D2>rsgb_lf_group@blacksheep.org</FONT></A> </DIV> <DIV><FONT face=3DArial><FONT size=3D2><B>Cc:</B> </FONT></FONT><A=20 title=3D"mailto:paul@abelian.netcom.co.uk STRG + Klicken, um = Verkn=FCpfung zu folgen"=20 href=3D""><FONT face=3DArial size=3D2>Paul</FONT></A> </DIV> <DIV><FONT face=3DArial><FONT size=3D2><B>Subject:</B> Re: VLF: TX on = 6.47 and=20 8.97</FONT></FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT><FONT face=3DArial = size=3D2></FONT><FONT=20 face=3DArial size=3D2></FONT><FONT face=3DArial size=3D2></FONT><FONT = face=3DArial=20 size=3D2></FONT><FONT face=3DArial size=3D2></FONT><FONT face=3DArial=20 size=3D2></FONT><FONT face=3DArial size=3D2><BR></FONT></DIV> <DIV><FONT face=3DArial size=3D2>Dear LF, Paul,</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>here's a short summary of today's VLF = kite=20 transmission. I'm sorry for the late notice, but the experiment=20 had not been planned ahead, and I wasn't sure if I could get = on at=20 all. Also, the kite I am using (a 0.8 m^2 delta toy bought=20 for 4.99 Euro) is a bit small for this sort of activity, and = really=20 requires a good and steady wind. </FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>The QTH was actually at 49.3874 N = 11.1692 E, a=20 few 100 meters from the former location reported earlier. The = GPS-controlled=20 carriers were on air </FONT></DIV> <DIV><FONT face=3DArial size=3D2> 11:15 - 12:15 6470.000 Hz = ~ 50 uW,=20 and </FONT></DIV> <DIV><FONT face=3DArial size=3D2> 12:30 - 13:10 8970.002 Hz = ~ 200 uW=20 (EMRP).</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>Getting on 6470 was easier than = expected. I=20 simply used the same "seven-bucket" coil, which resonates my 240 pF = home=20 antenna to 8.97 kHz. Connected to the kite wire, the resonance was = close=20 enough to 6.5 kHz to be tuned by the ferrite plate = variometer. Then=20 the drive for the audio amp was increased until the onset of = corona=20 sizzling at 0.25 A. At that point, the amp drew 10 A DC from = the car=20 battery and probably delivered around 50 W. After connecting mobile = internet=20 and staring at Stefan's grabber, I was positively surprised = to find a=20 faint trace there!</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>For the frequency change, I removed = the two=20 bottom coil buckets, which brought the resonance to ~ 8.5 kHz. Then I = had to=20 carefully pull the remaining 5 buckets apart, inserting bits of = plastic=20 foam material as spacers. Going through a few = iterations took about 10 minutes, and I got to "full power" (380 = mA,=20 100W) at 12:30. Unfortunately, the wind had started to calm by then, = and there=20 were several dips during this transmission. Finally at 13:10, the kite = landed=20 gently in the grass, and I decided to close down and pack up=20 early.</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>Traces from both transmissions were = visible on=20 DK7FC's 4.5 mHz "600" windows, and the second one also produced=20 a nice dash on the 0.45 mHz window. It is likely that these = signals would=20 be useful for a kite-to-kite QSO on either frequency, using 10 minute=20 dashes.</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>The screenshot from = F1AFJ has an=20 interesting dash before 13:00. The indicated frequency seems a = bit high=20 (8970.020 instead of 8970.002), which could perhaps be due to a small=20 samplerate calibration error. I am also not sure about the time=20 scale - judging by the width of the noise blobs, the = setting could=20 have been 11 mHz and 10 seconds per pixel. It would be nice=20 if Jean-Pierre could confirm the frequency calibration and = scroll=20 settings.</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>I also carefully inspected the OE3GHB = grabber,=20 which runs at 1.4 mHz resolution and seems to be very sensitive. = It=20 showed an unusually dark period of very low noise between 8 and = 11 UT=20 today. But no luck for my transmission there yet.</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV style=3D"FONT: 10pt Tahoma"><FONT face=3DArial>Well, in addition = to the=20 technical aspects, being outdoors in the warm wind was again = a rewarding=20 and enjoyable experience. </FONT></DIV> <DIV style=3D"FONT: 10pt Tahoma"><FONT = face=3DArial></FONT> </DIV> <DIV style=3D"FONT: 10pt Tahoma"><FONT face=3DArial>Best 73, and = thanks again for=20 the interest. </FONT></DIV> <DIV style=3D"FONT: 10pt Tahoma"><FONT = face=3DArial></FONT> </DIV> <DIV style=3D"FONT: 10pt Tahoma"><FONT face=3DArial>Markus = (DF6NM)</FONT></DIV> <DIV style=3D"FONT: 10pt Tahoma"><FONT = face=3DArial></FONT> </DIV> <DIV style=3D"FONT: 10pt Tahoma"><FONT face=3DArial>...</FONT></DIV> <DIV><B></B><FONT face=3DArial=20 size=3D2></FONT> </DIV></BLOCKQUOTE></BODY></HTML> ------=_NextPart_000_0010_01CC4ECA.3DBB7F00--