Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-md03.r1000.mx.aol.com (Internet Inbound) with ESMTP id 7937A380000C0; Sat, 30 Jul 2011 11:03:55 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1QnB41-000571-4U for rs_out_1@blacksheep.org; Sat, 30 Jul 2011 16:02:53 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1QnB3z-00056s-SG for rsgb_lf_group@blacksheep.org; Sat, 30 Jul 2011 16:02:51 +0100 Received: from nm6-vm0.bullet.mail.ukl.yahoo.com ([217.146.183.234]) by relay1.thorcom.net with smtp (Exim 4.63) (envelope-from ) id 1QnB3z-0000uz-NS for rsgb_lf_group@blacksheep.org; Sat, 30 Jul 2011 16:02:51 +0100 Received: from [217.146.183.210] by nm6.bullet.mail.ukl.yahoo.com with NNFMP; 30 Jul 2011 15:02:45 -0000 Received: from [217.146.183.41] by tm3.bullet.mail.ukl.yahoo.com with NNFMP; 30 Jul 2011 15:02:45 -0000 Received: from [127.0.0.1] by omp1026.mail.ukl.yahoo.com with NNFMP; 30 Jul 2011 15:02:45 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 258928.26810.bm@omp1026.mail.ukl.yahoo.com Received: (qmail 19692 invoked by uid 60001); 30 Jul 2011 15:02:45 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.co.uk; s=s1024; t=1312038165; bh=/eCDKkYpXIOsP5soLh20fjTheVcHkVnCI7BHkC/wNZM=; h=X-YMail-OSG:Received:X-Mailer:Message-ID:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=e6ci5lcNfNJks3w9MzvXCjS9UIp6mA6VkkdISassCRxCALb/3Ak/2J9XwB/RGKYR+nXUH/Tix6urPms4jZuRo7geAxAHMK4j6xGIFn9BBhTX5nIc8oU+eHKQohSLfaIuASLSWYyWIhbMsd2sRjSHQuTYCaCkqYpP4AiVswSMVtU= DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.co.uk; h=X-YMail-OSG:Received:X-Mailer:Message-ID:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=3gdWAecc1U3N5utZ4AarxRZar1XzUeWYsG/excafGTphKsC2daZBkIXfaUNGIw28AoCbT52KpENYtbQFZA46cMhL8s4pg2mVpTj1xC0TifE3UxD/PZ+yHboDHtCYM9sF/GPdZ75dkJqVmxO4m7FA+vXWW/+QLnAHb9o83wtxWHU=; X-YMail-OSG: WrXRmUcVM1n6_o0ry3LUkS4OKyqR65MxLxJ9f1XtadL2IZz F15.3AiqlaiHZ7XJCYBMW6sUogdBOsb.GkB5ceyBpsZYpXkcFPn72Yw.uz.B WywDEb3nthAYsfXjumtotTuGvj38iO665y5_yDJ7dFnWDb0wmRGuH7h0ofOO KXQqkNk6sEzV.lB09p_6IDPyWU07mdB3k0SrwLNsCq4dRSnTLMoF9IFc4UCq qc42hxv6eESQXz9rAw6Kxc6zpkE48qBRkAIOa14yVlkBmVbdSVnw.CcBJEAm ._GIpWeDr0vWo4Z_GswInLZJnXoKaoXClIUSDVoM3V.WmewecvEqdBkbMQzf AgZR9HSi5ZG6IlzMJyWU6BsQdGRoXhsy8us7ysZGgozQscW2qEN7HIRsZchL d0aLt86HOGJ9SE3pFOzEUE5vw1fpPU9yTmW9GcOhj8BV2n.P9Qamo.0YenvN VVQkUTtGgOFPCOg94IyhQapGE9HdxLSMwwX0mk8lKhZV9ZhguxFo7qJTMUfE QV6JPK5FqRsllCjZnEgj5d8qANi5PDikdVoJ7isd.S.xqVEi77UR9Hri31tl 0FQ-- Received: from [81.97.191.183] by web28513.mail.ukl.yahoo.com via HTTP; Sat, 30 Jul 2011 16:02:44 BST X-Mailer: YahooMailClassic/14.0.3 YahooMailWebService/0.8.112.310352 Message-ID: <1312038164.87304.YahooMailClassic@web28513.mail.ukl.yahoo.com> Date: Sat, 30 Jul 2011 16:02:44 +0100 (BST) From: Chris Osborn To: rsgb_lf_group@blacksheep.org In-Reply-To: <4E33EAB8.2020209@iup.uni-heidelberg.de> MIME-Version: 1.0 DomainKey-Status: good (testing) Subject: Re: VLF: DF6NM kite attempt Content-Type: multipart/alternative; boundary="0-1072398214-1312038164=:87304" 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: 1:2:500442816:93952408 X-AOL-SCOLL-URL_COUNT: 2 X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-d299.2 ; domain : yahoo.co.uk DKIM : pass x-aol-sid: 3039ac1d60574e341d5b15b8 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --0-1072398214-1312038164=:87304 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable VLF, I received a signal on the specified frequency at about 15 dB S/N I'll send a screen shot later. 73 Chris G3XIZ IO 92 UB --- On Sat, 30/7/11, Stefan Sch=E4fer wrot= e: From: Stefan Sch=E4fer Subject: Re: VLF: DF6NM kite attempt To: rsgb_lf_group@blacksheep.org Date: Saturday, 30 July, 2011, 12:27 =0A=0A=0A=0A =0AVLF, =0A =0AMarkus produces a strong signal, he is well visible in my DFCW-60=0Awind= ow at 8970.002 Hz in 174 km distance. He is 13 dB S/N at OK2BVG in=0A600!!!= A trace seems to come up at G3ZJO in the 6000 window. A small=0Apeak seems= to come up at TF3HZ... =0A =0Ahttp://simnet.is/halldorgudmunds/TF3HZ_VLFgrabber/index.html =0Ahttp://www.ok2bvg.cz/vlfgrabber/ =0Ahttp://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber.html =0Ahttp://g3zjo.bplaced.net/index.htm =0A =0AAny other receiving stations? =0A =0AI think this is his best signal radiated so far :-) =0A =0AThe DX season is coming back! :-) =0A =0A73, GL,=20 =0A =0AStefan/DK7FC =0A =0AAm 30.07.2011 09:52, schrieb Markus Vester:=0A=0A =0A=0A =0A =0A Dea= r LF,=0A =A0=0A today around noon, I will attempt=0Aanother kite=A0transm= ission from the same site. If all works well, I=0Awill=A0send=A0a=A01 mW ca= rrier on 8970.002=A0from around 11 to 14 UT.=0A =A0=0A Best regards,=0A = Markus (DF6NM)=0A =0A =20 =0A =0A =0A From: Markus Vester =0A =0A =0A =0A =0A Sent: Tuesday, = June 21, 2011 12:00 AM=0A To: rsgb_lf_group@blacksheep.org=0A =0A Subjec= t: VLF: DF6NM kite activity June 19=0A =0A =0A =20 =0A =0A Dear=0ADreamers,=0A =A0=0A thanks=0Avery much to everyone who c= ommented=A0on my signal yesterday night,=A0and=0Aall who=A0are running thei= r VLF grabbers.=0A =A0=0A Transmission:=0A =A0=0A My=0Asignal was on ai= r on 8970.002 Hz from 18:52 to 22:01, with a long break=0Afrom 19:26 to 19:= 52 due to a prolonged rain period, and=A0many shorter=0Ainterruptions cause= d by precipitation, low wind, a coil falling over,=0Aor a breaking antenna = connection.=0A =A0=0A I'm=0Aaware that an advanced notice would have been= valuable=A0for=0Apotential=A0receiving stations. But=A0I find it difficult= to=A0plan=0Aahead=A0this type of=A0activity. Yesterday even while setting = things up on=0Athe site, I was not at all sure=A0whether I would be able to= actually get=0Aon air for any significant time. =0A =A0=0A Site:=0A =A0= =0A The=A0location (49.3874 N 11.1692 E,=0A"JN59OJ02HX" for those who=A0pr= efer cryptic notations ;-)=A0was the=0Asame=A0as=A0in the experiment=A0on N= ov 13 last year (see email copy=A0at=0Abottom).=A0While Google Maps still s= hows=A0large patches of unused land=0Aaround the=A0former=A0US=A0airfield,= =A0"my" field=A0is=A0now=A0one of very=0Afew=A0undeveloped plots in the mid= dle of an industrial area, inhabited=0Amostly by large logistics companies.= Though=A0I=0Ahad originally=A0not intended to work into darkness,=A0I foun= d there was=0Astill=A0plenty of light from the surrounding truck parking an= d unloading=0Aareas.=0A =A0=0A Kite antenna and ground:=0A =A0=0A This = time=A0I used a=A04 sqm lifter kite=0A(HQ Power Sled L3.0, similar to=A0Ste= fan's smaller kite). It is held by a=0A150 m line. This may be stretching t= he limit a bit, but due to the=0Aslope and sag of the line I am sure that t= he=A0peak altitude=A0always=0Astayed below=A0100 m.=0A =A0=0A =0A The=0A= previously used=A00.4 mm magnet wire=A0had a voltage limit=A0of about 12 kV= =0Adue to corona appearing along the whole length. It has now been=0Areplac= ed=A0by insulated wire (0.25 sqmm, outer diameter 1.3 mm). The=0Atotal leng= th is 180 m,=A0with the last 30 m dangling down from the kite,=0Aintended t= o act as a sort of extra top load. Effective height would be=0Aaround 50 m,= giving 3.5 milliohm radiation resistance, or 1.3 mW EMRP=0Aat 0.6 A.=0A = =A0=0A At the western end of the unused=0Asite, there is a long mesh wire = fence running=A0north-south,=A0held by=0Asolid metal posts which=A0served= =A0very well both for anchoring and=0Agrounding. Total resistance of the an= tenna circuit was around 280 ohms=0A(including 140 ohms for the coil). This= is about half of=A0that=A0when I=0Aused the same kite antenna=A0in Bamberg= with only a few short ground pegs.=0A =A0=0A =0A The coil was placed be= low the kite line at about 3 m=A0from the=0Aanchor point, hoping to keep th= e=A0wire well above ground. However this=0Aturned out to be problematic=A0d= ue to the horizontal and vertical=0Amovement of the connection point. When = the kite was low and due west,=0Athe=A0wire=A0was too long and touched the = wet grass, exhibiting=A0pretty=0Alittle fireworks. When it went up or drift= ed aside, the=A0wire became too=0Ashort, and either plugged itself off, or = tipped over the whole coil.=0AYou guess how much=A0I like having to reconne= ct the ungrounded wire, with=0Adark clouds overhead and a slight drizzle go= ing down...=A0I twice found=0Amyself=A0holding down the=A0kite line with my= foot, then slowly stepping=0Aforward until the open end at least touched t= he earth.=A0Next time I=0Awill=A0definitely place the coil=A0much closer to= the anchor, and try to=0Ahold the=A0connection up=A0by means=A0of some ela= stic plastic tube.=0A =A0=0ACoil:=0A =A0=0A From the previous experiment= I knew=0Athat the wire capacitance was very close to 900 pF. During the=0A= afternoon, I experimented with=A0different=A0coil configurations, and found= =0Athat I could either use=A0four buckets (184 ohms) with a=A0large=A010=0A= cm=A0pitch (ie.=A09 Lego blocks), giving=A0about 8 mm radial clearance=0Abe= tween one coil layer and the inner radius=A0of the next bucket.=A0The=0Aoth= er option=A0was=A0three buckets (138 ohms), stuffed into one=A0another=A03= =0Acm pitch=A0and 2 mm clearance (see picture http://df6nm.bplaced.net/VLF/= pictures/two_coils_350mH.jpg).=0A =A0=0A Mainly for mechanical reasons, I= =0Aopted for the more compact three-bucket solution,=A0but this=A0turned ou= t=0Ato be the wrong choice.=A0With power applied, I heard=0Acorona=A0sizzle= s=A0around the coil at about 0.55 A (11 kV).=A0In darkness I=0Acould see=A0= violet seams near the bottom end of the upper two windings.=0AThis means th= at the maximum usable layer-to-layer voltage for this=0Adesign is about=A03= .7 kV. Next time I will definitely=A0go for the longer=0Aversion, which als= o has more surface exposed to the wind for heat=0Aremoval.=0A =A0=0A BTW= =A0all=A0seven buckets connected to=0A900 pF=A0resonate=A0at about 4.6 kHz = - Stefan, how about a 65 km band ;-)=0A =A0=0A Amplifier and power supply= :=0A =A0=0A Like before, I=A0used one channel=0Aof=A0a=A0class-B car-audi= o amp (Nitro 3000),=A0feeding a 12 : 80 turns=0Aferrite transformer origina= lly wound by DJ2LF. It delivered=A00.6 A=0Aantenna current (~ 100 W)=A0from= 12V x 13 A=A0DC input.=A0It was possible to=0Aturn the volume up to 0.7A, = but I did not=A0dare=A0to=A0run=A0that=A0level of=0Acorona permanently.=A0T= he amp was fed by a standalone 35 Ah lead-acid=0Abattery, which=A0was=A0rep= eatedly recharged via=A0jumper wires from the car=0Aengine during the latte= r half of the experiment.=0A =A0=0A Signal generation:=0A =A0=0A SpecLa= b's samplerate=A0was locked to=0ADHO, which=A0is very slightly (3 ppb) abov= e=A0its nominal frequency 23.4=0AkHz.=A0To keep the average phase steady, I= took care to never interrupt=0Athe software generator whenever I had to ta= ke the=A0carrier off=0Aair.=A0Anyway the=A0time series recorded by=0APaul N= icholson=A0shows two major phase jumps=A0around 19:40 (while the TX=0Awas o= ff) and 21:20, perhaps due to soundcard buffering issues.=A0One=0Aproblem I= did not see immediately was that the DHO ferrite antenna was=0Atoo close t= o one of the jumper wires,=A0temporarily picking up=0Ainterference when=A0t= he car alternator was running - once found, this one=0Awas easily fixed.=0A= =A0=0A Results:=0A =A0=0A Though the traces at TF3HZ (2547 km)=0Aand Y= O/4X1RF (1253 km) are close to the noise,=A0they are at the right=0Atime an= d frequency, and I=A0do not think=A0that they are=A0random pixels.=0AHalld= =F3r's trace even seems to show the outage period after the first=0Abright = dot.=A0=0A =A0=0A On my own grabber, I attempted=0Ato=A0compare=A0signal = levels from=A0DK7FC (-71 dB, 180 km) and myself (-43=0AdB, 4.5 km).=A0Corre= cting this difference (28 dB) by=A0the EMRP ratio (26=0AmW=A0/ 1.2 mW =3D 1= 3 dB), distance ratio (1/r =3D 32 dB)=A0plus=A0an=0Aadditional=A0nearfield = correction (1/r=B3 instead of 1/r from 4.5 to 5.3=0Akm=A0=3D 3 dB), we=A0fi= nd that Stefan was=A028+13-35=0AdB =3D 6 dB weaker than we would expect by = pure groundwave. This=0Acorresponds very well to the earlier experience tha= t there is a midday=0Askywave cancellation effect for about 200 km.=A0=0A = =A0=0A Best wishes,=0A Markus (DF6NM)=0A =A0=0A From: Stefan Sch=E4fer = =0A Sent: Monday, June 20,=0A2011 10:48 AM=0A To: rsgb_lf_group@blackshee= p.org =0A Subject: Re: VLF: DF6NM=0Aon 8970 Hz!! Fwd: Fwd: VLF: More food = for grabbers=0A =20 =0A =0A Hello Markus,=20 =0A =20 =0AThis was your strongest signal received here so far. Tell us about your= =0Arig! Where did the TX power come from? A battery? Must have been a big= =0Abattery or you must have had very low losses. =0A =20 =0ATransmitting during the night could be an interesting point. I could=0At= ry to use the 100m kite antenna on 8970 Hz as well. Then, no special=0Aperm= it would be needed but my signal would be 10 dB lower. Anyway this=0Acould = be interesting. Or i could try night transmissions on the fixed=0Aantenna..= .. =0A =20 =0AHappy to see more activity here again! :) =0A =20 =0A73, Stefan/DK7FC=0A ________________________________________=0A =A0=0A= From: Markus Vester =0A Sent: Sunday, November=0A14, 2010 12:04 AM=0A T= o: rsgb_lf_group@blacksheep.org=0A =0A Cc: Paul =0A Subject: Re: VLF: TX= on=0A6.47 and 8.97=0A =20 =0A =0A Dear=A0LF, Paul,=0A =A0=0A here's a short summary of today's=0A= VLF kite transmission. I'm sorry for the late notice, but=0Athe=A0experimen= t had=A0not been planned=A0ahead, and I wasn't sure if I could=0Aget on at = all. Also, the kite I am using=A0(a 0.8 m^2=A0delta toy bought=0Afor=A04.99= Euro)=A0is a bit small for this sort of activity, and really=0Arequires a = good and steady wind.=A0=A0=0A =A0=0A The QTH was actually at 49.3874 N= =0A11.1692 E, a few 100 meters from the former location reported earlier.= =0AThe GPS-controlled carriers were on air =0A =A011:15 - 12:15=A0 6470.00= 0 Hz ~ 50 uW,=0Aand =0A =A012:30 - 13:10=A0 8970.002 Hz ~ 200 uW=0A(EMRP).= =0A =A0=0A Getting on 6470 was easier than=0Aexpected. I simply used the = same "seven-bucket" coil, which resonates=0Amy 240 pF home antenna to 8.97 = kHz. Connected to the kite wire, the=0Aresonance was close enough to 6.5 kH= z to be tuned by the ferrite plate=0Avariometer.=A0Then the=A0drive for the= audio amp was increased=A0until the=0Aonset of corona sizzling at 0.25 A.= =A0At that point,=A0the amp drew 10 A DC=0Afrom the car battery and probabl= y delivered around 50 W. After=0Aconnecting mobile internet and staring at = Stefan's grabber, I was=0Apositively surprised to=A0find a faint trace ther= e!=0A =A0=0A For the frequency change, I removed=0Athe=A0two bottom coil = buckets, which brought the resonance to ~ 8.5 kHz.=0AThen I had to carefull= y pull the remaining 5 buckets apart,=A0inserting=0Abits of plastic foam=A0= material=A0as=A0spacers.=A0Going through a=A0few=0Aiterations took about 10= minutes, and I got to "full power"=A0(380 mA,=0A100W) at 12:30. Unfortunat= ely, the wind had started to calm by then,=0Aand there were several dips du= ring this transmission. Finally at 13:10,=0Athe kite landed gently in the= =A0grass, and I decided to close down and=0Apack up early.=0A =A0=0A Trac= es from both transmissions were=0Avisible on DK7FC's 4.5 mHz "600" windows,= and=A0the second one also=0Aproduced a=A0nice dash on the 0.45 mHz window.= It is likely that these=0Asignals would be useful for a kite-to-kite QSO o= n either frequency,=0Ausing 10 minute dashes.=0A =A0=0A The=A0screenshot = from F1AFJ=A0has an=0Ainteresting dash before 13:00.=A0The indicated freque= ncy seems a bit high=0A(8970.020 instead of 8970.002), which could perhaps = be due to a small=0Asamplerate calibration error. I am also not sure about = the time=0Ascale=A0=A0- judging by the width of the noise blobs, the settin= g could=0Ahave been 11 mHz and=A010 seconds per pixel. It would be nice=0Ai= f=A0Jean-Pierre=A0could confirm the frequency calibration and scroll=0Asett= ings.=0A =A0=0A I also carefully inspected the=0AOE3GHB grabber, which=A0= runs at 1.4 mHz resolution and seems to be very=0Asensitive. It showed an u= nusually=A0dark period of very low noise between=0A8 and 11 UT today. But n= o luck=A0for my transmission there yet.=0A =A0=0A Well, in addition to th= e technical aspects, being=0Aoutdoors in the warm wind was again a=A0reward= ing and enjoyable=0Aexperience. =0A =A0=0A Best 73, and thanks again for = the interest. =0A =A0=0A Markus (DF6NM)=0A =A0=0A ...=0A =A0=0A=0A =0A --0-1072398214-1312038164=:87304 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
VLF,

I received a signal on the specif= ied frequency at about 15 dB S/N
I'll send a screen shot later.

7= 3
Chris G3XIZ
IO 92 UB

--- On Sat, 30/7/11, Stefan Sch=E4fe= r <schaefer@iup.uni-heidelberg.de> wrote:

From: Stefan Sch=E4fer <schaefer@iup.uni-heidelberg.de&g= t;
Subject: Re: VLF: DF6NM kite attempt
To: rsgb_lf_group@blacksheep.= org
Date: Saturday, 30 July, 2011, 12:27

=0A=0A=0A=0A =0AVLF,
=0A
=0AMarkus produces a strong signal, he is= well visible in my DFCW-60=0Awindow at 8970.002 Hz in 174 km distance. He = is 13 dB S/N at OK2BVG in=0A600!!! A trace seems to come up at G3ZJO in the= 6000 window. A small=0Apeak seems to come up at TF3HZ...
=0A
=0Ah= ttp://simnet.is/halldorgudmunds/TF3HZ_VLFgrabber/index.html
=0Ahttp://www.ok2bvg.cz/vlfgrabbe= r/
=0Ahttp://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC= _VLF_Grabber.html
=0Ahttp://g3zjo.bplaced.net/index.htm
=0A
=0AAny other receivin= g stations?
=0A
=0AI think this is his best signal radiated so far :-= )
=0A
=0AThe DX season is coming back! :-)
=0A
=0A73, GL,
= =0A
=0AStefan/DK7FC
=0A
=0AAm 30.07.2011 09:52, schrieb Markus Ves= ter:=0A
=0A =0A=0A =0A =0A Dear LF,
=0A
 =0A
today around noon, I will attemp= t=0Aanother kite transmission from the same site. If all works well, I= =0Awill send a 1 mW carrier on 8970.002 from around 11 = to 14 UT.
=0A
 
=0A
Best regards,
=0A
Markus (DF6NM)
=0A
=0A <= div>
=0A
=0A
=0A =0A
=0A
=0A
=0A
=0A
= Sent: Tuesday, June 21, 2011 12:00 AM
=0A =0A
Subject: VLF: = DF6NM kite activity June 19
=0A
=0A
=0A

=0A <= /div>=0A
Dear=0ADreamers,
=0A
 =0A
thanks=0Avery much to everyone who commented on my signal yester= day night, and=0Aall who are running their VLF grabbers.
=0A
 
=0A
Transmission:
=0A
 
=0A
My=0Asignal was on air on 8970.002 H= z from 18:52 to 22:01, with a long break=0Afrom 19:26 to 19:52 due to a pro= longed rain period, and many shorter=0Ainterruptions caused by precipi= tation, low wind, a coil falling over,=0Aor a breaking antenna connection.<= /font>
=0A
 
=0A
I'm=0Aaware that an ad= vanced notice would have been valuable for=0Apotential receiving = stations. But I find it difficult to plan=0Aahead this type = of activity. Yesterday even while setting things up on=0Athe site, I w= as not at all sure whether I would be able to actually get=0Aon air fo= r any significant time.
=0A
 
= =0A
Site:
=0A
 = ;
=0A
The location (49.3874= N 11.1692 E,=0A"JN59OJ02HX" for those who prefer cryptic notations ;-= ) was the=0Asame as in the experiment on Nov 13 last ye= ar (see email copy at=0Abottom). While Google Maps still shows&nb= sp;large patches of unused land=0Aaround the former US airfi= eld, "my" field is now one of very=0Afew undevelop= ed plots in the middle of an industrial area, inhabited=0Amostly by large l= ogistics companies. Though I=0Ahad ori= ginally not intended to work into darkness, I found there was=0As= till plenty of light from the surrounding truck parking and unloading= =0Aareas.
=0A
 
=0A
Kite antenna and ground:
=0A
 =0A
This time I used a 4 = sqm lifter kite=0A(HQ Power Sled L3.0, similar to Stefan's smaller kit= e). It is held by a=0A150 m line. This may be stretching the limit a bit, b= ut due to the=0Aslope and sag of the line I am sure that the peak alti= tude always=0Astayed below 100 m.
=0A
 =0A =0A
The=0Apreviously used 0.= 4 mm magnet wire had a voltage limit of about 12 kV=0Adue to coro= na appearing along the whole length. It has now been=0Areplaced by ins= ulated wire (0.25 sqmm, outer diameter 1.3 mm). The=0Atotal length is 180 m= , with the last 30 m dangling down from the kite,=0Aintended to act as= a sort of extra top load. Effective height would be=0Aaround 50 m, giving = 3.5 milliohm radiation resistance, or 1.3 mW EMRP=0Aat 0.6 A.=
=0A
 
=0A At the western end of the unused=0Asite, = there is a long mesh wire fence running north-south, held by=0Aso= lid metal posts which served very well both for anchoring and=0Ag= rounding. Total resistance of the antenna circuit was around 280 ohms=0A(in= cluding 140 ohms for the coil). This is about half of that when I= =0Aused the same kite antenna in Bamberg with only a few short ground = pegs.
=0A
 
=0A
=0A
The coil was placed below the kite line at about 3 m = from the=0Aanchor point, hoping to keep the wire well above ground. Ho= wever this=0Aturned out to be problematic due to the horizontal and ve= rtical=0Amovement of the connection point. When the kite was low and due we= st,=0Athe wire was too long and touched the wet grass, exhibiting=  pretty=0Alittle fireworks. When it went up or drifted aside, the = ;wire became too=0Ashort, and either plugged itself off, or tipped over the= whole coil.=0AYou guess how much I like having to reconnect the ungro= unded wire, with=0Adark clouds overhead and a slight drizzle going down...&= nbsp;I twice found=0Amyself holding down the kite line with my fo= ot, then slowly stepping=0Aforward until the open end at least touched the = earth. Next time I=0Awill definitely place the coil much clo= ser to the anchor, and try to=0Ahold the connection up by means&n= bsp;of some elastic plastic tube.
=0A
 
=0ACoil:
=0A
 
=0A
From= the previous experiment I knew=0Athat the wire capacitance was very close = to 900 pF. During the=0Aafternoon, I experimented with different = coil configurations, and found=0Athat I could either use four buckets = (184 ohms) with a large 10=0Acm pitch (ie. 9 Lego block= s), giving about 8 mm radial clearance=0Abetween one coil layer and th= e inner radius of the next bucket. The=0Aother option was&nb= sp;three buckets (138 ohms), stuffed into one another 3=0Acm pitc= h and 2 mm clearance (see picture http://df6nm.bplaced.net/VLF/pictures/two_c= oils_350mH.jpg).
=0A
 
=0A
Mainly for mechanical reasons, I=0Aopted for the more= compact three-bucket solution, but this turned out=0Ato be the w= rong choice. With power applied, I heard=0Acorona sizzles ar= ound the coil at about 0.55 A (11 kV). In darkness I=0Acould see = violet seams near the bottom end of the upper two windings.=0AThis means th= at the maximum usable layer-to-layer voltage for this=0Adesign is about&nbs= p;3.7 kV. Next time I will definitely go for the longer=0Aversion, whi= ch also has more surface exposed to the wind for heat=0Aremoval.=0A
 
=0A
BTW = all seven buckets connected to=0A900 pF resonate at about 4.= 6 kHz - Stefan, how about a 65 km band ;-)
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 =0A
Amplifier and power supply:
=0A
 
=0A =
Like before, I used one channel= =0Aof a class-B car-audio amp (Nitro 3000), feeding a 12 : 8= 0 turns=0Aferrite transformer originally wound by DJ2LF. It delivered = 0.6 A=0Aantenna current (~ 100 W) from 12V x 13 A DC input. = It was possible to=0Aturn the volume up to 0.7A, but I did not dare&nb= sp;to run that level of=0Acorona permanently. The amp w= as fed by a standalone 35 Ah lead-acid=0Abattery, which was repea= tedly recharged via jumper wires from the car=0Aengine during the latt= er half of the experiment.
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=0A
Signal generation:
=0A
 =
=0A
SpecLab's samplerate w= as locked to=0ADHO, which is very slightly (3 ppb) above its nomi= nal frequency 23.4=0AkHz. To keep the average phase steady, I took car= e to never interrupt=0Athe software generator whenever I had to take the&nb= sp;carrier off=0Aair. Anyway the = time series recorded by=0APaul Nicholson shows two major phase jumps&n= bsp;around 19:40 (while the TX=0Awas off) and 21:20, perhaps due to soundca= rd buffering issues. One=0Aproblem I did not see immediately wa= s that the DHO ferrite antenna was=0Atoo close to one of the jumper wires,&= nbsp;temporarily picking up=0Ainterference when the car alternator was= running - once found, this one=0Awas easily fixed.
=0A
<= font size=3D"2" face=3D"Arial"> 
=0A
Results:
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=0A
Though the traces at TF3HZ (2547 km)=0Aand YO/4X= 1RF (1253 km) are close to the noise, they are at the right=0Atime and= frequency, and I do not think that they are random pixels.= =0AHalld=F3r's trace even seems to show the outage period after the first= =0Abright dot. 
=0A
 
=0A
On my own grabber, I attempted=0Ato compare = ;signal levels from DK7FC (-71 dB, 180 km) and myself (-43=0AdB, 4.5 k= m). Correcting this difference (28 dB) by the EMRP ratio (26=0AmW=  / 1.2 mW =3D 13 dB), distance ratio (1/r =3D 32 dB) plus an= =0Aadditional nearfield correction (1/r=B3 instead of 1/r from 4.5 to = 5.3=0Akm =3D 3 dB), we find that Stefan was 28+13-35=0AdB =3D 6 dB weaker than we would expect b= y pure groundwave. This=0Acorresponds very well to the earlier experience t= hat there is a midday=0Askywave cancellation effect for about 200 km. =
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=0A
Best wishes,
=0A
Markus= (DF6NM)
=0A
 
=0A
From:<= /b> Stefan Sch= =E4fer
=0A
= Sent: Monday, June 20,=0A2011 10:48 AM
=0A =0A
Subject: = Re: VLF: DF6NM=0Aon 8970 Hz!! Fwd: Fwd: VLF: More food for grabbers<= /font>
=0A

=0A =0A
Hello Markus,
=0A
=0ATh= is was your strongest signal received here so far. Tell us about your=0Arig= ! Where did the TX power come from? A battery? Must have been a big=0Abatte= ry or you must have had very low losses.
=0A
=0ATransmitting during= the night could be an interesting point. I could=0Atry to use the 100m kit= e antenna on 8970 Hz as well. Then, no special=0Apermit would be needed but= my signal would be 10 dB lower. Anyway this=0Acould be interesting. Or i c= ould try night transmissions on the fixed=0Aantenna....
=0A
=0AHapp= y to see more activity here again! :)
=0A
=0A73, Stefan/DK7FC
=0A
__________________________= ______________
=0A
 
=0A =0A
= Sent: Sunday, November=0A14, 2010 12:04 AM
=0A To: rsgb_lf_group@blac= ksheep.org=0A
=0A
Cc: Paul
=0A
= Subject: Re: VLF: TX on=0A6.47 and 8.97
=0A

=0A
=0A=
Dear LF, Paul,
=0A =
 
=0A
here's a short = summary of today's=0AVLF kite transmission. I'm sorry for the late notice, = but=0Athe experiment had not been planned ahead, and I wasn'= t sure if I could=0Aget on at all. Also, the kite I am using (a 0.8 m^= 2 delta toy bought=0Afor 4.99 Euro) is a bit small for this = sort of activity, and really=0Arequires a good and steady wind.  =
=0A
 
=0A
The QTH was actually at 49.3874 N=0A11.1692 E, a few 100 meters from the = former location reported earlier.=0AThe GPS-controlled carriers were on air=
=0A
 11:15 - 12:15=   6470.000 Hz ~ 50 uW,=0Aand
=0A
 12:30 - 13:10  8970.002 Hz ~ 200 uW=0A(EMRP).
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=0A
Get= ting on 6470 was easier than=0Aexpected. I simply used the same "seven-buck= et" coil, which resonates=0Amy 240 pF home antenna to 8.97 kHz. Connected t= o the kite wire, the=0Aresonance was close enough to 6.5 kHz to be tuned by= the ferrite plate=0Avariometer. Then the drive for the audio amp= was increased until the=0Aonset of corona sizzling at 0.25 A. At= that point, the amp drew 10 A DC=0Afrom the car battery and probably = delivered around 50 W. After=0Aconnecting mobile internet and staring at St= efan's grabber, I was=0Apositively surprised to find a faint trace the= re!
=0A
 
=0A
For the frequency change, I removed=0Athe two bottom coil buckets= , which brought the resonance to ~ 8.5 kHz.=0AThen I had to carefully pull = the remaining 5 buckets apart, inserting=0Abits of plastic foam m= aterial as spacers. Going through a few=0Aiterations to= ok about 10 minutes, and I got to "full power" (380 mA,=0A100W) at 12:= 30. Unfortunately, the wind had started to calm by then,=0Aand there were s= everal dips during this transmission. Finally at 13:10,=0Athe kite landed g= ently in the grass, and I decided to close down and=0Apack up early.
=0A
 
=0A
= Traces from both transmissions were=0Avisible on DK7FC's 4.5 mHz "600" wind= ows, and the second one also=0Aproduced a nice dash on the 0.45 m= Hz window. It is likely that these=0Asignals would be useful for a kite-to-= kite QSO on either frequency,=0Ausing 10 minute dashes.
=0A  
=0A
The screensho= t from F1AFJ has an=0Ainteresting dash before 13:00. The indicate= d frequency seems a bit high=0A(8970.020 instead of 8970.002), which could = perhaps be due to a small=0Asamplerate calibration error. I am also not sur= e about the time=0Ascale  - judging by the width of the noise blo= bs, the setting could=0Ahave been 11 mHz and 10 seconds per pixel. It = would be nice=0Aif Jean-Pierre could confirm the frequency calibr= ation and scroll=0Asettings.
=0A
 
=0A
I also carefully inspected the=0AOE3GHB grabb= er, which runs at 1.4 mHz resolution and seems to be very=0Asensitive.= It showed an unusually dark period of very low noise between=0A8 and = 11 UT today. But no luck for my transmission there yet.
= =0A
 
=0A
Well, in addition to the technical aspects, being=0Aoutdoors in the w= arm wind was again a rewarding and enjoyable=0Aexperience. =0A
 
=0A
Best 73, and thanks again for the inter= est.
=0A
 
=0A Markus (DF6NM)=0A
 
=0A
...
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=0A =0A
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