Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by klubnl.pl (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id x2D9mgIm023885 for ; Wed, 13 Mar 2019 10:48:49 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1h40Hw-0006zb-1D for rs_out_1@blacksheep.org; Wed, 13 Mar 2019 09:35:04 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1h40Hu-0006zS-Gd for rsgb_lf_group@blacksheep.org; Wed, 13 Mar 2019 09:35:02 +0000 Received: from emout02.email.it ([212.97.34.18]) by relay1.thorcom.net with esmtp (Exim 4.91) (envelope-from ) id 1h40Hq-0004ST-FV for rsgb_lf_group@blacksheep.org; Wed, 13 Mar 2019 09:35:01 +0000 Received: from emout02.email.it (localhost [127.0.0.1]) by emout02.email.it (Postfix) with ESMTP id 8B5A882187 for ; Wed, 13 Mar 2019 10:34:55 +0100 (CET) Received: from x220.localnet (62-11-169-236.dialup.tiscali.it [62.11.169.236]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by emout02.email.it (Postfix) with ESMTPSA id 58A3282183 for ; Wed, 13 Mar 2019 10:34:55 +0100 (CET) From: Claudio Pozzi To: rsgb_lf_group@blacksheep.org Date: Wed, 13 Mar 2019 10:34:55 +0100 Message-ID: <1808729.0J1joYhzyE@x220> User-Agent: KMail/4.14.1 (Linux/3.16.0-4-amd64; KDE/4.14.2; x86_64; ; ) In-Reply-To: References: <1811819281.3633936.1552408406386.ref@mail.yahoo.com> <1811819281.3633936.1552408406386@mail.yahoo.com> MIME-Version: 1.0 X-Spam-Score: -0.4 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: On Tuesday, March 12, 2019 10:03:45 PM you wrote: > From observation: when a charged cloud passess by, you can get about 15mm > sparks from a dipole for 80m hung between two 7-story buildings. This > [...] Content analysis details: (-0.4 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low trust [212.97.34.18 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (smtp01[at]email.it) 0.2 FREEMAIL_ENVFROM_END_DIGIT Envelope-from freemail username ends in digit (smtp01[at]email.it) 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 MIME_QP_LONG_LINE RAW: Quoted-printable line longer than 76 chars X-Scan-Signature: 53c114a438b331b17dd9e5f4c84cbbe7 Subject: Re: LF: Re: Re Loomis? & ... 12.47 Hz Content-Type: multipart/alternative; boundary="nextPart14114791.Fo011gWJjA" Content-Transfer-Encoding: 7Bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.6 required=5.0 tests=FROM_ENDS_IN_NUMS,HTML_60_70, HTML_MESSAGE,RISK_FREE 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 This is a multi-part message in MIME format. --nextPart14114791.Fo011gWJjA Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="iso-8859-1" On Tuesday, March 12, 2019 10:03:45 PM you wrote: > From observation: when a charged cloud passess by, you can get about=20= 15mm > sparks from a dipole for 80m hung between two 7-story buildings. This= > happens more often than once per second. Say 40m horizontal section=20= + 30m > vertical coax, the capacitance is around: >=20 > 40m*6pF/m + 30m*5pF/m =3D 390pF >=20 > 15mm is about 15kV. >=20 > (390*10^-12 [F] ) * 15000 [V] / 1[s] =3D 0.00000585 [A] =3D 5.85 uA > (i hope i got the units right :) >=20 > The charging current is probably a bit higher than calculated because= > there is some leakage to ground. >=20 > But this is an extreme case when a cloud passess by, and the charging= =20 is > probably via corona discharge (so it's "no risk no fun" again). >=20 > Before calculating this i thought the current would be a few orders o= f > magnitude higher. >=20 > VY 73 >=20 > Jacek / SQ5BPF I suggest this paper for theory: https://arxiv.org/pdf/0906.1280[1]=20 And in the following link a simple measuring instrument: https://arxiv.org/pdf/physics/0701296.pdf[2]=20 73 de Claudio, ik2pii >=20 > On Tue, 12 Mar 2019, Markus Vester wrote: > > Date: Tue, 12 Mar 2019 16:33:26 +0000 (UTC) > > From: Markus Vester > > Reply-To: rsgb_lf_group@blacksheep.org > > To: rsgb_lf_group@blacksheep.org > > Subject: Re: LF: Re: Re Loomis? & ... 12.47 Hz > >=20 > > Hi Stefan, > >=20 > > why not drive the antenna in parallel resonance? This would provide= a > > better impedance match to the low current high voltage DC source. > > You'd preferably want a high voltage transistor, which could also > > operate in class-C with low duty cycle. > >=20 > > From my experience, 100 uA DC seems overly optimistic. Best I got=20= from my > > ant (40 m of wire) was 1 to 2 uA, which was actually during a > > precipitation static event (aka Grabber whiteout). In fair weather,= the > > current is normally not measurable with a 10 Mohm millivoltmeter, i= .e. > > less than ~ 0.1 nA. > >=20 > > Best 73, > > Markus > >=20 > > -----Urspr=FCngliche Mitteilung----- > > Von: DK7FC > > An: rsgb_lf_group > > Verschickt: Di, 12. Mrz 2019 16:09 > > Betreff: Re: LF: Re: Re Loomis? & ... 12.47 Hz > >=20 > > Well, today: The circuit in operation on the INV-L since last night= , > > 100% WSPR @MF. The reports on the local RX in 20m distance were=20 between > > 0...+7 dB at night and -11...-9 dB in daylight. > > On the tree grabber in 3.5 km distance the signal was only detectab= le=20 at > > night, levels reaching about -24 dB in average. Nothing in daylight= . > >=20 > > Where does the energy come from? It must be the voltages coming=20 from > > other transmitters (DC to HF) which leave voltages up to the range = of=20 1 > > V at this antenna. This RX voltage spectrum is modulated by the cir= cuit > > and radiates a very weak signal. That's why the signal is about 13 = dB > > weaker in daylight. In this experiment this is an unwanted effect. = It > > causes some kind of offset, i.e. it lowers the SNR difference to a > > signal generated by cloud charges. So the 'sky-current' must be=20 higher > > to become clearly observable. And it is easier to detect it in dayl= ight. > > The effect should be less expressed at LF because the external=20 voltages > > from other transmitters are the same but the expected voltage from = a=20 100 > > uA 'sky-current' will be 475/137 higher, i.e. the system is 10 dB m= ore > > sensitive for the observation of the expected effect. > > Unfortunately there is no LF monitor on the tree... > >=20 > > Anyway i need to be more patient. There has been no static rain yet= > > anyway... > > Meanwhile i read a bit about Miller capacity and > > https://en.wikipedia.org/wiki/Cascode. I built one out of two BS170= FETs > > somehow it does not work yet. > >=20 > > 73, Stefan > >=20 > > Am 11.03.2019 17:24, schrieb DK7FC: > > > ...the circuit is completed (attached). > > > First i used a simple rectangular input signal coming from the=20= source, > > > over an ferrite core. The gate voltage was +-10V. But then,=20 obviously > > > due to the FETs internal reverse transfer capacitance i got a 200= =20 mVpp > > > output across 470 pF (tested in the lab, later to be replaced by = the > > > antenna). I built a test source for the assumed 100 uA 'sky-curre= nt' > > > by using a 1 kV voltage source and 10 MOhm in series. As assumed,= =20 a > > > linear rising voltage was observed during the off-times of the FE= T. > > > However, together with the voltage coming over the Crss, the=20 residual > > > rms value even dropped! Thus i had to reduce the gate peak-peak > > > voltage and ended up with the circuit shown in the attachment.=20= There > > > is a DC offset and the AC component is as low as possible. The=20= reduced > > > the unwanted voltage 8 mV. > > > Then, 50 mV rms at 475 kHz at 100 uA DC 'sky-current'. > > >=20 > > > How far will a 50 mV rms WSPR signal be detectable? And will the > > > 'sky-current' reach 100 uA at all? At least the signal strength w= ill > > > rise with the square of that current, so the report are nearly as= =20 good > > > as a current measurement. > > >=20 > > > 73, Stefan > > >=20 > > > Am 11.03.2019 13:29, schrieb DK7FC: > > >> Hello Jim, > > >>=20 > > >> Yes, indeed. > > >> I'm now preparing the circuit and want to set it up in the eveni= ng. =0D=0A =0D=0A --=0D=0A ZE-Light e ZE-Pro: servizi zimbra per caselle con dominio email.it, per tutti i dettagli =0D=0A Clicca qui http://posta.email.it/caselle-di-posta-z-email-it/?utm_campaign=3Demail_Zimbra_102014=3Dmain_footer/f=0D=0A =0D=0A Sponsor:=0D=0A Caselle con tuo dominio su piattaforma Zimbra, fino a 30 GB di spazio, sincronizzazione dati e backup=0D=0A Clicca qui: http://adv.email.it/cgi-bin/foclick.cgi?mid=3D13324&d=3D13-3=0D=0A --nextPart14114791.Fo011gWJjA Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset="iso-8859-1"

On = Tuesday, March 12, 2019 10:03:45 PM you wrote:

>= ; From observation: when a charged cloud passess by, you can get about = 15mm

>= ; sparks from a dipole for 80m hung between two 7-story buildings. This=

>= ; happens more often than once per second. Say 40m horizontal section += 30m

>= ; vertical coax, the capacitance is around:

>= ;

>= ; 40m*6pF/m + 30m*5pF/m =3D 390pF

>= ;

>= ; 15mm is about 15kV.

>= ;

>= ; (390*10^-12 [F] ) * 15000 [V] / 1[s] =3D 0.00000585 [A] =3D 5.85 uA

>= ; (i hope i got the units right :)

>= ;

>= ; The charging current is probably a bit higher than calculated because=

>= ; there is some leakage to ground.

>= ;

>= ; But this is an extreme case when a cloud passess by, and the charging= is

>= ; probably via corona discharge (so it's "no risk no fun" aga= in).

>= ;

>= ; Before calculating this i thought the current would be a few orders o= f

>= ; magnitude higher.

>= ;

>= ; VY 73

>= ;

>= ; Jacek / SQ5BPF

 

I s= uggest this paper for theory:

 

https://arxiv.org/pdf/0906.1280

 

And= in the following link a simple measuring instrument:

 

https://arxiv.org/pdf/physics/0= 701296.pdf

 

73 = de Claudio, ik2pii

 

 

 

>= ;

>= ; On Tue, 12 Mar 2019, Markus Vester wrote:

>= ; > Date: Tue, 12 Mar 2019 16:33:26 +0000 (UTC)

>= ; > From: Markus Vester <markusvester@aol.com>

>= ; > Reply-To: rsgb_lf_group@blacksheep.org

>= ; > To: rsgb_lf_group@blacksheep.org

>= ; > Subject: Re: LF: Re: Re Loomis? & ... 12.47 Hz

>= ; >

>= ; > Hi Stefan,

>= ; >

>= ; > why not drive the antenna in parallel resonance? This would prov= ide a

>= ; > better impedance match to the low current high voltage=A0DC sour= ce.

>= ; > You'd=A0preferably want a high voltage transistor, which could a= lso

>= ; > operate=A0in class-C with low duty cycle.

>= ; >

>= ; > From my experience, 100 uA DC seems=A0overly optimistic. Best I=A0= got from my

>= ; > ant (40 m of wire) was 1 to 2 uA, which was actually during a

>= ; > precipitation static event (aka Grabber whiteout). In fair weath= er, the

>= ; > current is normally not measurable with a 10 Mohm millivoltmeter= , i.e.

>= ; > less than ~ 0.1 nA.

>= ; >

>= ; > Best 73,

>= ; > Markus

>= ; >

>= ; > -----Urspr=FCngliche Mitteilung-----

>= ; > Von: DK7FC <selberdenken@posteo.de>

>= ; > An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>

>= ; > Verschickt: Di, 12. Mrz 2019 16:09

>= ; > Betreff: Re: LF: Re: Re Loomis? & ... 12.47 Hz

>= ; >

>= ; > Well, today: The circuit in operation on the INV-L since last ni= ght,

>= ; > 100% WSPR @MF. The reports on the local RX in 20m distance were = between

>= ; > 0...+7 dB at night and -11...-9 dB in daylight.

>= ; > On the tree grabber in 3.5 km distance the signal was only detec= table at

>= ; > night, levels reaching about -24 dB in average. Nothing in dayli= ght.

>= ; >

>= ; > Where does the energy come from? It must be the voltages coming = from

>= ; > other transmitters (DC to HF) which leave voltages up to the ran= ge of 1

>= ; > V at this antenna. This RX voltage spectrum is modulated by the = circuit

>= ; > and radiates a very weak signal. That's why the signal is about = 13 dB

>= ; > weaker in daylight. In this experiment this is an unwanted effec= t. It

>= ; > causes some kind of offset, i.e. it lowers the SNR difference to= a

>= ; > signal generated by cloud charges. So the 'sky-current' must be = higher

>= ; > to become clearly observable. And it is easier to detect it in d= aylight.

>= ; > The effect should be less expressed at LF because the external v= oltages

>= ; > from other transmitters are the same but the expected voltage fr= om a 100

>= ; > uA 'sky-current' will be 475/137 higher, i.e. the system is 10 d= B more

>= ; > sensitive for the observation of the expected effect.

>= ; > Unfortunately there is no LF monitor on the tree...

>= ; >

>= ; > Anyway i need to be more patient. There has been no static rain = yet

>= ; > anyway...

>= ; > Meanwhile i read a bit about Miller capacity and

>= ; > https://en.wikipedia.org/wiki/Cascode. I built one out of two BS= 170 FETs

>= ; > somehow it does not work yet.

>= ; >

>= ; > 73, Stefan

>= ; >

>= ; > Am 11.03.2019 17:24, schrieb DK7FC:

>= ; > > ...the circuit is completed (attached).

>= ; > > First i used a simple rectangular input signal coming from = the source,

>= ; > > over an ferrite core. The gate voltage was +-10V. But then,= obviously

>= ; > > due to the FETs internal reverse transfer capacitance i got= a 200 mVpp

>= ; > > output across 470 pF (tested in the lab, later to be replac= ed by the

>= ; > > antenna). I built a test source for the assumed 100 uA 'sky= -current'

>= ; > > by using a 1 kV voltage source and 10 MOhm in series. As as= sumed, a

>= ; > > linear rising voltage was observed during the off-times of = the FET.

>= ; > > However, together with the voltage coming over the Crss, th= e residual

>= ; > > rms value even dropped! Thus i had to reduce the gate peak-= peak

>= ; > > voltage and ended up with the circuit shown in the attachme= nt. There

>= ; > > is a DC offset and the AC component is as low as possible. = The reduced

>= ; > > the unwanted voltage 8 mV.

>= ; > > Then, 50 mV rms at 475 kHz at 100 uA DC 'sky-current'.

>= ; > >

>= ; > > How far will a 50 mV rms WSPR signal be detectable? And wil= l the

>= ; > > 'sky-current' reach 100 uA at all? At least the signal stre= ngth will

>= ; > > rise with the square of that current, so the report are nea= rly as good

>= ; > > as a current measurement.

>= ; > >

>= ; > > 73, Stefan

>= ; > >

>= ; > > Am 11.03.2019 13:29, schrieb DK7FC:

>= ; > >> Hello Jim,

>= ; > >>

>= ; > >> Yes, indeed.

>= ; > >> I'm now preparing the circuit and want to set it up in = the evening.

>= ; > >> Found an IRF820 in the 'junk box', a good choice. Or, m= aybe even a

>= ; > >> BS170 will work. It handles 60V only but i had the foll= owing thought:

>= ; > >>

>= ; > >> The ERP at a constant voltage across the antenna (say 5= 0 V rms at the

>= ; > >> fundamental frequency) will rise with the sqare of the = frequency (for

>= ; > >> electrically short antennas). But that voltage will not= be constant

>= ; > >> in practice. It will drop linearly with the frequency (= ~ 1/f)

>= ; > >> because the sky-current is assumed to be constant and t= he charge up

>= ; > >> time is T/2. And, doubling the voltage at the antenna w= ill also rise

>= ; > >> the ERP by a factor of 4. All in all it means the the E= RP is

>= ; > >> constant, or independend of the frequency!?

>= ; > >> That means, it would be wise to select a band where man= y RX stations

>= ; > >> are watching and propagation is promising. The number o= f RX stations

>= ; > >> is higher at MF but (groundwave) propagation is better = at LF.

>= ; > >> Since the peak voltage will be lower at MF (shorter cha= rge-up time),

>= ; > >> MF is less critical.

>= ; > >>

>= ; > >> And which mode?! I think the best choice is a 100% duty= cycle WSPR

>= ; > >> beacon. It also has the advantage that one can check th= e results in

>= ; > >> the database. And there are many RX stations, even in t= he groundwave

>= ; > >> distance and even in less than 100 km here. And i have = my tree which

>= ; > >> can detect small differences at very low levels.

>= ; > >> At MF, the BS170 is a good choice i think. And it can b= e driven by a

>= ; > >> Raspi directly, maybe with a ferrite transformer in the= gate-source

>= ; > >> path, to decouple the shack from the antenna...

>= ; > >>

>= ; > >> If that works, one could try LF.

>= ; > >>

>= ; > >> 73, Stefan

>= ; > >>

>= ; > >> Am 10.03.2019 20:18, schrieb hvanesce@comcast.net:

>= ; > >>> All great ideas in the preceding messages.

>= ; > >>>

>= ; > >>> A steady signal from the 136 kHz sky-current transm= itter could

>= ; > >>> indicate that a data bit might be available later f= rom the 10 Hz

>= ; > >>> sky-current transmitter.

>= ; > >>>

>= ; > >>> Agreed, the triggered gap sounds better than an HV = vacuum relay (for

>= ; > >>> jitter and reliability).

>= ; > >>>

>= ; > >>> Sounds like the voltage divider doesn't need to be = more than a

>= ; > >>> gigohm, but perhaps for future reference: a reliabl= e 50kV 1 terohm

>= ; > >>> divider can be made very easily: encapsulate ten 10= 0 gigohm

>= ; > >>> resistors in hard epoxy, being sure not to touch th= em during

>= ; > >>> assembly. A single linearity calibration after curi= ng will be remain

>= ; > >>> valid +/- 10% for years in varying humidity and tem= perature.

>= ; > >>>

>= ; > >>> 73,

>= ; > >>>

>= ; > >>> Jim AA5BW

>= ; > >>>

>= ; > >>>

>= ; > >>> -----Original Message-----

>= ; > >>> From: owner-rsgb_lf_group@blacksheep.org

>= ; > >>> [mailto:owner-rsgb_lf_group@blacksheep.org] On Beha= lf Of DK7FC

>= ; > >>> Sent: Sunday, March 10, 2019 5:52 AM

>= ; > >>> To: rsgb_lf_group@blacksheep.org

>= ; > >>> Subject: Re: LF: Re: Re Loomis?&=A0 ... 12.47 H= z

>= ; > >>>

>= ; > >>> Hi Jacek, DC,

>= ; > >>>

>= ; > >>> Yes yes, i already see a new project for summer :-)=

>= ; > >>>

>= ; > >>> A floating antenna will charge up to a voltage wher= e the E field

>= ; > >>> strength is high enough to start partial discharges= , something like

>= ; > >>> 20 kV maybe, depending on the wire diameters and ho= mogenity of the

>= ; > >>> arrangement, also on pressure and humidity. So ther= e will be a

>= ; > >>> voltage limit given by the arrangement. But a highe= r field strength

>= ; > >>> in summer will help to charge up the antenna faster= , so higher

>= ; > >>> switching frequencies are possible.

>= ; > >>>

>= ; > >>> One could build/use a triggered spark gap,

>= ; > >>> https://en.wikipedia.org/wiki/Trigatron, this will = hold higher

>= ; > >>> voltages and you can connect the trigger directly t= o a ublox GPS

>= ; > >>> module running e.g. at 3 Hz :-) I think this will g= ive a lower

>= ; > >>> jitter than when using a vacuum relay.

>= ; > >>> Could this work over my 3.5 km path if i use my inv= -L? I don't think

>= ; > >>> so.

>= ; > >>> The time to integrate will be to short and there wi= ll be much QRN

>= ; > >>> during such an experiment, so the SNR will be very = low. Currently

>= ; > >>> (at 12.47 Hz) i already have 15 kV DC available...<= /p>

>= ; > >>>

>= ; > >>> Anyway, interesting questions, there is something i= nteresting to

>= ; > >>> learn.

>= ; > >>> Maybe i will do a few experiments in summer. Buildi= ng a HV divider

>= ; > >>> and measurement should be no problem...

>= ; > >>>

>= ; > >>> 73, Stefan

>= ; > >>>

>= ; > >>> PS: Assuming 100 uA constant current 'coming from t= he sky', my 470

>= ; > >>> pF antenna would charge up with 213 kV/s, so it wou= ld be possible to

>= ; > >>> switch at 10 Hz and get a 21 kV 'square wave'. Mayb= e the harmonics

>= ; > >>> could be detected easier than the fundamental frequ= ency.

>= ; > >>> At 137 kHz it would be 1.5 V only (0.53 V rms). Thi= s can be switched

>= ; > >>> with a normal FET! Imagine we would switch the ante= nna permanently

>= ; > >>> at, say 136.172 kHz, using a FET and a ublox GPS mo= dule. Then, as

>= ; > >>> soon as the field strength is high enough, we would= see a carrier on

>= ; > >>> the grabbers? We need to try that out! Amazing! Wha= t a great hobby

>= ; > >>> we have!?!

>= ; > >>> PPS: For this experiment, the antenna can be series= resonated, which

>= ; > >>> would help to concentrate the energy to the wanted = spectrum...

 


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