Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dh03.r1000.mx.aol.com (Internet Inbound) with ESMTP id BC31D38000090; Mon, 20 Jun 2011 18:39:03 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1QYn6f-0003AP-GN for rs_out_1@blacksheep.org; Mon, 20 Jun 2011 23:38:09 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1QYn6e-0003AG-B8 for rsgb_lf_group@blacksheep.org; Mon, 20 Jun 2011 23:38:08 +0100 Received: from imr-da05.mx.aol.com ([205.188.105.147]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1QYn6b-00062P-4s for rsgb_lf_group@blacksheep.org; Mon, 20 Jun 2011 23:38:08 +0100 Received: from mtaout-ma02.r1000.mx.aol.com (mtaout-ma02.r1000.mx.aol.com [172.29.41.2]) by imr-da05.mx.aol.com (8.14.1/8.14.1) with ESMTP id p5KMbmum014639; Mon, 20 Jun 2011 18:37:48 -0400 Received: from White (nrbg-4dbe7943.pool.mediaWays.net [77.190.121.67]) by mtaout-ma02.r1000.mx.aol.com (MUA/Third Party Client Interface) with ESMTPA id 9384AE00011D; Mon, 20 Jun 2011 18:37:44 -0400 (EDT) Message-ID: From: "Markus Vester" To: , "Paul" References: <4DFE5EA9.2090101@iup.uni-heidelberg.de> <9B4318767B6849FFB89F8294D336ACEC@White> <4DFF094E.6070008@iup.uni-heidelberg.de> Date: Tue, 21 Jun 2011 00:37:46 +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-SCOLL-SCORE: 0:2:471678560:93952408 X-AOL-SCOLL-URL_COUNT: 0 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: VLF: DF6NM kite activity June 19 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0007_01CC2FAB.7120A660" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.1 required=5.0 tests=HTML_20_30,HTML_MESSAGE, HTML_TITLE_EMPTY,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-SCOLL-SCORE: 0:2:473566048:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d41174dffcc073f13 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none Dies ist eine mehrteilige Nachricht im MIME-Format. ------=_NextPart_000_0007_01CC2FAB.7120A660 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable sorry, this was sent out before completion. Now also with a link to the = picture of the coils. 73, Markus 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_0007_01CC2FAB.7120A660 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
sorry, this was sent out before = completion. Now=20 also with a link to the picture of the coils. 73, = Markus

From: Markus Vester
Sent: Tuesday, June 21, 2011 12:00 AM
To: rsgb_lf_group@blacksheep.org= =20
Subject: VLF: DF6NM kite activity June 19

Dear=20 Dreamers,
 
thanks very much to=20 everyone who commented on my signal yesterday night, and all=20 who are running their VLF grabbers.
 
Transmission:
 
My = signal was on air=20 on 8970.002 Hz from 18:52 to 22:01, with a long break from 19:26 to = 19:52 due to=20 a prolonged rain period, and many shorter interruptions caused by=20 precipitation, low wind, a coil falling over, or a breaking antenna=20 connection.
 
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 = of activity. Yesterday even while setting things up on the site, I = was not=20 at all sure whether I would be able to actually get on air for any=20 significant time.
 
Site:
 
The location (49.3874 N 11.1692 E, = "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 middle=20 of an industrial area, inhabited mostly by large logistics companies. = Though I had originally not intended to = work into=20 darkness, I found there was still plenty of light from the = surrounding=20 truck parking and unloading areas.
 
Kite antenna and ground:
 
This time I used a 4 sqm = lifter kite (HQ=20 Power Sled L3.0, similar to Stefan's smaller kite). It is held by a = 150 m=20 line. This may be stretching the limit a bit, but due to the slope and = sag of=20 the line I am sure that the peak altitude always stayed = below 100=20 m.
 
The previously used 0.4 mm magnet=20 wire had a voltage limit of about 12 kV due to corona = appearing along=20 the whole length. It has now been replaced by insulated wire (0.25 = sqmm,=20 outer diameter 1.3 mm). The total length is 180 m, with the last 30 = m=20 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 = resistance,=20 or 1.3 mW EMRP at 0.6 A.
 
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 = 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.
 
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 too=20 long and touched the wet grass, exhibiting pretty little fireworks. = When it=20 went up or drifted aside, the wire became too short, and either = plugged=20 itself off, or tipped over the whole coil. You guess how much I = like having=20 to reconnect the ungrounded wire, with dark clouds overhead and a slight = drizzle=20 going down... I twice found myself holding down the kite = line=20 with my foot, then slowly stepping forward until the open end at least = touched=20 the earth. Next time I will definitely place the = coil much closer=20 to the anchor, and try to hold the connection up by = means of some=20 elastic plastic tube.
 
Coil:
 
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 = (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 http:/= /df6nm.bplaced.net/VLF/pictures/two_coils_350mH.jpg).
 
Mainly for mechanical reasons, I opted = for the more=20 compact three-bucket solution, but this turned out to be the = wrong=20 choice. With power applied, I heard corona sizzles around = the=20 coil at about 0.55 A (11 kV). In darkness I could see violet = seams=20 near the bottom end of the upper two windings. This means that the = maximum=20 usable layer-to-layer voltage for this design is about 3.7 kV. Next = time I=20 will definitely go for the longer version, which also has more = surface=20 exposed to the wind for heat removal.
 
BTW all seven buckets = connected to 900=20 pF resonate at about 4.6 kHz - Stefan, how about a 65 km band=20 ;-)
 
Amplifier and power=20 supply:
 
Like before, I used one channel=20 of a class-B car-audio amp (Nitro 3000), feeding a 12 : = 80 turns=20 ferrite transformer originally wound by DJ2LF. It delivered 0.6 A = antenna=20 current (~ 100 W) from 12V x 13 A DC input. It was = possible to=20 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.
 
Signal generation:
 
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 = air. Anyway=20 the 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. One=20 problem I did not see immediately was that the DHO ferrite antenna was = too close=20 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.
 
Results:
 
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 = frequency,=20 and I do not think that they are random pixels. = Halld=F3r's trace=20 even seems to show the outage period after the first bright=20 dot. 
 
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 ratio=20 (26 mW / 1.2 mW =3D 13 dB), distance ratio (1/r =3D 32 = dB) plus an=20 additional nearfield correction (1/r=B3 instead of 1/r from 4.5 to = 5.3=20 km =3D 3 dB), we find that Stefan was 28+13-35 dB =3D 6 dB weaker than we would expect by pure = groundwave.=20 This corresponds very well to the earlier experience that there is a = midday=20 skywave cancellation effect for about 200 km. 
 
Best wishes,
Markus (DF6NM)
 
From:=20 Stefan Sch=E4fer
Sent: Monday, June 20, = 2011 10:48=20 AM
To: rsgb_lf_group@blacksheep.org
Subject: Re: VLF: DF6NM on = 8970 Hz!!=20 Fwd: Fwd: VLF: More food for grabbers

Hello Markus,

This was your = strongest=20 signal received here so far. Tell us about your rig! Where did the TX = power come=20 from? A battery? Must have been a big battery or you must have had very = low=20 losses.

Transmitting during the night could be an interesting = point. I=20 could try to use the 100m kite antenna on 8970 Hz as well. Then, no = special=20 permit would be needed but my signal would be 10 dB lower. Anyway this = could be=20 interesting. Or i could try night transmissions on the fixed=20 antenna....

Happy to see more activity here again! :)

73,=20 Stefan/DK7FC
________________________________________
 
From:=20 Markus Vester
Sent: Sunday, November 14, = 2010 12:04=20 AM
To: rsgb_lf_group@blacksheep.org
Cc: Paul
Subject: Re: VLF: TX on = 6.47 and=20 8.97

Dear LF, Paul,
 
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.  
 
The QTH was actually at 49.3874 N = 11.1692 E, a few=20 100 meters from the former location reported earlier. The GPS-controlled = carriers were on air
 11:15 - 12:15  6470.000 Hz ~ = 50 uW, and=20
 12:30 - 13:10  8970.002 Hz ~ = 200 uW=20 (EMRP).
 
Getting on 6470 was easier than = expected. I simply=20 used the same "seven-bucket" coil, which resonates my 240 pF home = antenna to=20 8.97 kHz. Connected to the kite wire, the resonance was close enough to = 6.5 kHz=20 to be tuned by the ferrite plate variometer. Then the drive = for the=20 audio amp was increased until the onset of corona sizzling at 0.25=20 A. At that point, the amp drew 10 A DC from the car battery = and=20 probably delivered around 50 W. After connecting mobile internet and = staring at=20 Stefan's grabber, I was positively surprised to find a faint trace=20 there!
 
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=20 iterations took about 10 minutes, and I got to "full power" (380 = mA, 100W)=20 at 12:30. Unfortunately, the wind had started to calm by then, and there = were=20 several dips during this transmission. Finally at 13:10, the kite landed = gently=20 in the grass, and I decided to close down and pack up = early.
 
Traces from both transmissions were = visible on=20 DK7FC's 4.5 mHz "600" windows, and the second one also produced = a nice=20 dash on the 0.45 mHz window. It is likely that these signals would be = useful for=20 a kite-to-kite QSO on either frequency, using 10 minute = dashes.
 
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 = samplerate=20 calibration error. I am also not sure about the time scale  - = judging=20 by the width of the noise blobs, the setting could have been 11 mHz = and 10=20 seconds per pixel. It would be nice if Jean-Pierre could = confirm the=20 frequency calibration and scroll settings.
 
I also carefully inspected the OE3GHB = grabber,=20 which runs at 1.4 mHz resolution and seems to be very sensitive. It = showed=20 an unusually dark period of very low noise between 8 and 11 UT = today. But=20 no luck for my transmission there yet.
 
Well, in addition to = the=20 technical aspects, being outdoors in the warm wind was again = a rewarding=20 and enjoyable experience.
 
Best 73, and thanks = again for=20 the interest.
 
Markus = (DF6NM)
 
...
 
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