Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mb03.r1000.mx.aol.com (Internet Inbound) with ESMTP id 731DB3800009A; Thu, 24 May 2012 20:30:56 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1SXiPf-0001f7-6q for rs_out_1@blacksheep.org; Fri, 25 May 2012 01:29:51 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1SXiPe-0001ey-Ek for rsgb_lf_group@blacksheep.org; Fri, 25 May 2012 01:29:50 +0100 Received: from imr-db01.mx.aol.com ([205.188.91.95]) by relay1.thorcom.net with esmtp (Exim 4.77) (envelope-from ) id 1SXiPa-0003Oh-O2 for rsgb_lf_group@blacksheep.org; Fri, 25 May 2012 01:29:49 +0100 Received: from mtaout-mb02.r1000.mx.aol.com (mtaout-mb02.r1000.mx.aol.com [172.29.41.66]) by imr-db01.mx.aol.com (8.14.1/8.14.1) with ESMTP id q4P0Td5x004559 for ; Thu, 24 May 2012 20:29:39 -0400 Received: from White (nrbg-4dbfbd85.pool.mediaWays.net [77.191.189.133]) by mtaout-mb02.r1000.mx.aol.com (MUA/Third Party Client Interface) with ESMTPA id 00E7BE000121 for ; Thu, 24 May 2012 20:29:35 -0400 (EDT) Message-ID: From: "Markus Vester" To: References: <1B5243A8767941DDAFA2BE89A6626A30@White> <7AF00527873248F895DCCA6964C033CC@White> Date: Fri, 25 May 2012 02:29:33 +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 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20110426; t=1337905779; bh=Wjkd7jxhy5lyIjsu864LSYzVoTQVcrJpklv2Ru9EsuU=; h=From:To:Subject:Message-ID:Date:MIME-Version:Content-Type; b=n0BTdyUBgKxJurKdSf7X/rbyWRax6JmckHNnC5tw0NJDjBvFlqlsHVHjyhzeym57g pD2AZv9P+p7uq/7GZPzxD1EfLLatU2Blq69BMhYDwrxJF44QzrU6bng7PBVSRiFMZe uWu8WZNH3dnBKPgZjsKh3odxPi7C6yOQ4dlXpRAE= X-AOL-SCOLL-SCORE: 0:2:393847232:93952408 X-AOL-SCOLL-URL_COUNT: 0 X-Spam-Score: 0.3 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: My transmisssion was on air between 20:30 and 22:50, and consisted of no more than two one-hour dashes on 137780.00 Hz. It looks like the 1.9 mHz window at the bottom of the G4WGT grabber http://myweb.tiscali.co.uk/wgtaylor/grabber2.html also managed to pull my feeble signal out of the noise after 22 UT. Going by the visible Loran lines, Gary's frequency scale currently reads 0.4 Hz low. Distance between JN59NJ69es and IO83QO is around 1059 km. [...] Content analysis details: (0.3 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [205.188.91.95 listed in list.dnswl.org] 0.3 URIBL_RHS_DOB Contains an URI of a new domain (Day Old Bread) [URIs: blacksheep.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (markusvester[at]aol.com) -0.0 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay domain -0.0 SPF_PASS SPF: sender matches SPF record 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: 479f887a0af49374011bd47f9dfa3263 Subject: Re: LF: Microwatts and microhertz Content-Type: multipart/alternative; boundary="----=_NextPart_000_000B_01CD3A1E.388E4450" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.9 required=5.0 tests=HTML_30_40,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-SCOLL-SCORE: 0:2:428412448:93952408 X-AOL-SCOLL-URL_COUNT: 0 X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-m012.2 ; domain : mx.aol.com DKIM : pass x-aol-sid: 3039ac1d60174fbed2bf2893 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_000B_01CD3A1E.388E4450 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable My transmisssion was on air between 20:30 and 22:50, and consisted of no = more than two one-hour dashes on 137780.00 Hz. It looks like the 1.9 mHz window at the bottom of the G4WGT grabber http://myweb.tiscali.co.uk/wgtaylor/grabber2.html=20 also managed to pull my feeble signal out of the noise after 22 UT. = Going by the visible Loran lines, Gary's frequency scale currently reads = 0.4 Hz low. Distance between JN59NJ69es and IO83QO is around 1059 km. Best 73, Markus (DF6NM) From: Markus Vester=20 Sent: Friday, May 25, 2012 12:05 AM To: rsgb_lf_group@blacksheep.org=20 Subject: LF: Microwatts and microhertz=20 Two nights ago (May 22/23, 21:30-2:50), I sent a long carrier on 137780 = Hz with 250 =B5W from my indoor antenna. To my amazement, the signal was = picked up in the 420 =B5Hz spectrogram on Chris' excellent grabber in = Bucharest, 1256 km from here: http://qsl.net/4x1rf/yo/lfgrabber.htm Although I actually started transmitting during a local thunderstorm, = QRN in Romania was relatively low at the time, with Chris' propagation = plot indicating 50 dB SNR for DCF39 and 60 dB for HGA22. The signal from = the loop is normally also visible on the 22 mHz TA windows at DK7FC, = DM4TR and (sometimes) OE3GHB. Tonight since 20:30, I'm having another go, sending my suffix in = QRSS-1200 mode. Best 73, Markus (DF6NM) From: Markus Vester=20 Sent: Saturday, May 05, 2012 11:50 PM To: rsgb_lf_group@blacksheep.org=20 Subject: LF: Indoor Transmit Loop Today I have experimented with an indoor transmit loop for 136 kHz. First I attempted to measure the efficiency of a small test loop, 6 = turns and 66 cm diameter. It was made from a 12.1 meter piece of = 729-strand Decca litz wire (same that Stefan used for his famous loading = coil). Resonating with 23 nF styroflex gave a Q of 400, ie. 0.12 ohm = series resistance. Theoretical radiation resistance (above ground) would = be about 12 nanoohms, predicting an efficiency of about -70 dB. Then I = tuned to 138.83 kHz and measured -61.0 dBm available receive power from = DCF39. Assuming a fieldstrength of 3 mV/m here, an idealized lossless = loop or Marconi should deliver +8.2 dBm. Thus efficiency of the test = loop was -69.2 dB, in good agreement to theory. This shows that there is = little attenuation of magnetic fields in the walls and the roof, despite = the thin aluminium vapor barrier above me. To improve efficiency and power capability, I then dismantled the little = loop and reused the litz wire for a large single-turn loop. This is = about 3.5 m wide wall-to wall, 2.5 m high floor to ceiling, oriented = east-west for best signal towards Heidelberg. The loop was resonated = with 83.3nF, made of 10 pieces 33nF / 2kV FKP-1 capacitors, in 2s-5p = configuration. At 137 kHz, each capacitor is thermally limited to about = 6 A rms (30 A total). As expected, both the inductance and the Q factor = were lower (Q=3D72, 0.19 ohm loss). Presumably the extra 70 milliohms = were contributed by absorption in steel reinforcement in the floor and = walls. The radiation resistance of an 8.8 sqm loop should be about 0.23 = microohms, thus predicting 1.2 ppm (-59 dB) efficiency. Before the on air tests, I had calibrated the DK7FC grabber receiver = (180 km) using my normal LF Marconi, which has a known -30 dB = efficiency. A 136.17 kHz carrier from a signal generator (13 dBm, 20 = =B5W radiated power) produced a level of about -89 dB in Stefan's Eu = window. During the morning hours, noise was a low -105 dB in Heidelberg. The big loop was then matched to 50 ohms using 16:1 turns on a ferrite = ring (AL 4 uH). Fine tuning to 136.17 kHz was achieved by 0.44 uF in = series to one of the cap branches, and by slightly deforming the loop = geometry. Then I carefully applied power, expecting fireworks at any = moment, or all sorts of unwanted EMC effects due to the magnetic = nearfield. To my surprise, none of this happened. Going up to full 200 = watts silently produced 32 A in the loop, with no adverse effects on = electonics or radios in the vicinity. Only the small ferrite transformer = became hot after a short while. Recalculating core magnetisation (6V = rms, 0.5 cm^2) gave 0.2 tesla peak which is way too much. This was = easily mitigated by going to 32 turns primary and 2 turns secondary. For the on air-tests, I had inserted 100 kohm into the Marconi uplead to = eliminate possible coupling and reradiation. Despite the higher = afternoon QRN, signals from the loop were immediately received in = Heidelberg, at -78 dB and 16 dB SNR. Thus radiated power was about 0.25 = mW, and efficiency -59 dB, just as predicted. To double check, I = temporarily reconnected the Marconi and transmitted a dash with full = power. Due to slightly lower load impedance (40 ohms) the TX now = produced 250 W (ie. 0.25 W EMRP). As expected, the signal in Heidelberg = indeed went up by 30 dB. During the following hour, SNR was actually good enough to marginally = read a slow Hell transmission from the indoor antenna. More pics are at http://df6nm.bplaced.net/LF/Indoor_Loop/ . Well, so what is this good for? Transmit during a thunderstorm? Maybe = there's not much one can do with this kind of power, but the experiment = was certainly instructive, and good fun. Best 73, Markus (DF6NM) ------=_NextPart_000_000B_01CD3A1E.388E4450 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
My transmisssion was on air between = 20:30 and=20 22:50, and consisted of no more than two one-hour dashes on 137780.00=20 Hz.
 
It looks like the 1.9 = mHz window at=20 the bottom of the G4WGT grabber
http://myweb.t= iscali.co.uk/wgtaylor/grabber2.html 
also managed to pull my feeble = signal out of=20 the noise after 22 UT. Going by the visible Loran lines, = Gary's frequency=20 scale currently reads 0.4 Hz low. Distance between = JN59NJ69es and=20 IO83QO is around 1059 km.
 
Best 73,
Markus (DF6NM)

From: Markus Vester
Sent: Friday, May 25, 2012 12:05 AM
To: rsgb_lf_group@blacksheep.org= =20
Subject: LF: Microwatts and microhertz

Two nights ago (May 22/23, 21:30-2:50), = I sent a=20 long carrier on 137780 Hz with 250 =B5W from my indoor antenna. = To my amazement, the signal was picked up in the = 420 =B5Hz=20 spectrogram on Chris' excellent grabber in Bucharest, 1256 km from=20 here:
 http://qsl.net/4x1rf/yo/lf= grabber.htm
 
Although I actually started = transmitting during a=20 local thunderstorm, QRN in Romania was relatively low at the time, with = Chris'=20 propagation plot indicating 50 dB SNR for DCF39 and 60 dB for = HGA22. The=20 signal from the loop is normally also visible on the 22 mHz TA = windows at DK7FC, DM4TR and (sometimes) OE3GHB.
 
Tonight since 20:30, I'm having another = go, sending=20 my suffix in QRSS-1200 mode.
 
Best 73,
Markus (DF6NM)
 
 

From: Markus Vester
Sent: Saturday, May 05, 2012 11:50 PM
To: rsgb_lf_group@blacksheep.org= =20
Subject: LF: Indoor Transmit Loop

Today I have experimented with an = indoor=20 transmit loop for 136 kHz.
 
First I attempted to measure the efficiency of a small test = loop, 6=20 turns and 66 cm diameter. It was made from a 12.1 meter piece of = 729-strand=20 Decca litz wire (same that Stefan used for his famous loading=20 coil). Resonating with 23 nF styroflex gave a Q of = 400, ie. 0.12=20 ohm series resistance. Theoretical radiation = resistance (above=20 ground) would be about 12 nanoohms, predicting an efficiency = of about=20 -70 dB. Then I tuned to 138.83 kHz and measured -61.0 dBm available = receive=20 power from DCF39. Assuming a fieldstrength of 3 mV/m here, an idealized = lossless=20 loop or Marconi should deliver +8.2 dBm. Thus efficiency of = the test=20 loop was -69.2 dB, in good agreement to theory. This shows that = there is=20 little attenuation of magnetic fields in the walls and the = roof,=20 despite the thin aluminium vapor barrier above = me.
 
To improve efficiency and power = capability,=20 I then dismantled the little loop and reused the litz = wire for=20 a large single-turn loop. This is about 3.5 m wide wall-to = wall, 2.5 m=20 high floor to ceiling, oriented east-west for=20 best signal towards Heidelberg. The loop was = resonated with=20 83.3nF, made of 10 pieces 33nF / 2kV FKP-1 capacitors, in 2s-5p=20 configuration. At 137 kHz, each capacitor is thermally limited = to about 6 A rms (30 A total). As=20 expected, both the inductance and the Q factor were = lower (Q=3D72, 0.19=20 ohm loss). Presumably the extra 70 milliohms were contributed = by=20 absorption in steel reinforcement in the floor and walls. The radiation resistance of an 8.8 sqm loop = should be=20 about 0.23 microohms, thus predicting 1.2 ppm (-59 dB)=20 efficiency.
 
Before the on air tests, I=20 had calibrated the DK7FC grabber receiver (180 km) using my = normal LF=20 Marconi, which has a known -30 dB efficiency. A 136.17 kHz=20 carrier from a signal generator (13 dBm, 20 =B5W radiated power) = produced a=20 level of about -89 dB in Stefan's Eu window. During the = morning hours,=20 noise was a low -105 dB in Heidelberg.
 
The big loop was then matched to 50 ohms using 16:1=20 turns on a ferrite ring (AL 4 uH). Fine tuning to 136.17 kHz was = achieved=20 by 0.44 uF in series to one of the cap branches, and by slightly = deforming the=20 loop geometry. Then I carefully applied power, expecting fireworks = at any=20 moment, or all sorts of unwanted EMC effects due to the magnetic = nearfield. To=20 my surprise, none of this happened. Going up to full 200 = watts silently=20 produced 32 A in the loop, with no adverse effects on electonics or = radios=20 in the vicinity. Only the small = ferrite=20 transformer became hot after a short while. Recalculating core=20 magnetisation (6V rms, 0.5 cm^2) gave 0.2 tesla peak=20 which is way too much. This was easily mitigated by going to = 32 turns=20 primary and 2 turns secondary.
 
For the on air-tests, I had = inserted 100=20 kohm into the Marconi uplead to eliminate possible coupling and = reradiation.=20 Despite the higher afternoon QRN, signals from the loop were immediately = received in Heidelberg, at -78 dB and 16 dB SNR. Thus radiated=20 power was about 0.25 mW, and efficiency -59 dB, just = as predicted. To double check, I temporarily reconnected the Marconi and = transmitted a=20 dash with full power. Due to slightly lower load impedance (40 = ohms) the TX=20 now produced 250 W (ie. 0.25 W EMRP). As expected, the signal = in=20 Heidelberg indeed went up by 30 dB.
 
During the following hour, SNR = was actually=20 good enough to marginally read a slow Hell transmission from the indoor = antenna.=20 More pics are at
http://df6nm.bplaced.ne= t/LF/Indoor_Loop/ .
 
Well, so what is this good for? = Transmit during a=20 thunderstorm? Maybe there's not much one can do with this kind of = power,=20 but the experiment was certainly instructive, and good=20 fun.
 
Best 73,
Markus (DF6NM)
 
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