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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:            Hi ELF,        Stefan DK7FC said>>…better to actually measure that'sky-current'   >>before doing such RF experiments. If 100 uA isactually unrealistic and Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [74.6.130.121 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 (mrsocion[at]aol.com) 0.0 HTML_MESSAGE BODY: HTML included in message X-Scan-Signature: d7e11363ac319cfd7f6e42df098e1b8e Subject: LF: Re ELF & ... 12.47 Hz Content-Type: multipart/alternative; boundary="----=_Part_5687371_1629512964.1552679367112" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: *** X-Spam-Status: No, hits=3.1 required=5.0 tests=FORGED_MUA_MOZILLA,HTML_50_60, HTML_FONTCOLOR_BLUE,HTML_FONTCOLOR_UNKNOWN,HTML_MESSAGE 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 ------=_Part_5687371_1629512964.1552679367112 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable =C2=A0=C2=A0=C2=A0=C2=A0=20 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 Hi ELF,=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 = =C2=A0Stefan DK7FC said>>=E2=80=A6better to actually measure that'sky-curre= nt'=20 =C2=A0 >>before doing such RF experiments. If 100 uA isactually unrealistic= and=20 =C2=A0>>1 uA is more realistic, then the signal would be even 40 dB weakert= han=20 =C2=A0=C2=A0 >>expected, which makesit all quite useless.=20 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 Jim W5EST asks: If more signal i= s needed,=C2=A0would it help to augment the Inv-L with a longertop hat or b= ig top-capacitance area to get the signal strength up?=C2=A0=C2=A0=C2=A0 Al= though Pennock=E2=80=99s 1912 patent hadballoon-carried meshes in mind,=C2= =A0could aground-based mesh=C2=A0 like Pennock's help,=C2=A0or=C2=A0some = =C2=A0large multi-wire top hat ditto? http://pat2pdf.org/patents/pat1014719= .pdf=C2=A0(1912) Apparatus for Collecting ElectricalEnergy.=C2=A0=C2=A0 Or = would two or more Inv-L'sspaced apart at least several tens of meters and c= onnected together be usefulto get more current. =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 =C2=A0Re Jim AA5BW said >>Sounds like = the voltage divider doesn't need to be more than a =C2=A0>>gigohm, but perhaps forfuture reference: a reliable 50kV 1terohm di= vider can be made =C2=A0>>very easily: encapsulate ten 100 gigohm resistors inhard epoxy, bei= ng sure not to =C2=A0>>touch them duringassembly. A single linearity calibration after cur= ing will be remain =C2=A0=C2=A0>>valid +/- 10% for years in varyinghumidity and temperature.= =C2=A0=C2=A0=20 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 Jim W5EST asks: =C2=A0=C2=A0What pream= pcircuit is used in the DK7FC 12.67Hz receiver?=C2=A0=C2=A0Does it have a g= igohm or terohm input impedance to less imperfectlymatch to the high input = impedance of the atmosphere?=C2=A0=C2=A0=C2=A0 If not, could the design be = improved for abetter match?=C2=A0=C2=A0 Would perhaps a 1 nFblocking capaci= tor C in series with a gigohm R, =C2=A0with R across the gate of a preamp F= ET, keepatmospheric DC voltage from zapping the FET and let the FET amplify= the 12.67Hzsinusoid.=C2=A0=C2=A0=C2=A01nF x 1 Gigohm =3D 1 sec. time const= ant so 12.67Hz would easily get through to the FET gate.=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0 I don=E2=80=99t know if SNR wouldbe increased, but seems= like the more signal (with perhaps less noise) the RXgets from the preamp,= the better-positioned one is to apply filtering andprocessing to deal with= low SNR. =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 Re Stefan DK7FC said:=C2=A0>> =E2=80=A6It ca= uses some kind of offset, i.e. it lowers =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 >>the SNR difference to a signal gener= ated by cloud charges. =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 Jim W5EST comments:=C2=A0=C2=A0 =C2=A0Even i= f Stefan meant something else, hissentence got me to thinking about whether= the 5KV ELF on the TX antenna perhaps offsets ordiverts a tiny amount of a= tmospheric current entering the RX antenna.=C2=A0 We'd think of the atmosph= ere as having equipotential surface(s)=C2=A0high in big=C2=A0mass of resist= ive material in which the ELF TX and RX=C2=A0antennas are embedded circuit-= wise at ground level.=C2=A0 In other words, maybe we could think of the12.6= 7Hz experiment as using the 5KV ELF at the TX antenna to very slightlyperio= dically disturb the atmospheric currents in the RX antenna a few kilometers= away.=C2=A0 Unlike Loomis, who apparently imagined a highly conductive laye= r=C2=A0at tropospheric=C2=A0altitude,=C2=A0we'd picture=C2=A0only high resi= stivity throughout=C2=A0a volume of calm weather troposphere . =C2=A0=C2=A0= I=E2=80=99ll try to=C2=A0describe this ideaquantitively in another ELF=C2= =A0post. GL & 73, Jim H=C2=A0=C2=A0 W5EST ------=_Part_5687371_1629512964.1552679367112 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
     <= /span>
      Hi ELF,
  &n= bsp;     Stefan DK7FC said >>=E2=80=A6better to actually measure that 'sky-current'
  >>before doing such RF experiments. If 100 uA is actually unrealistic and
 >>1 uA is more realistic, then the signal would be even 40 dB w= eaker than
   >>expected, which makes it all quite useless.
        Jim W5EST asks: If more signal i= s needed, would it help to a= ugment the Inv-L with a longer top hat or big top-capacitance area to get the signal strength up?    Although Pennock=E2=80= =99s 1912 patent had balloon-carried meshes in mind, could a ground-based mesh  like Pennock's help, or some  large = multi-wire top hat ditto? http://pat2pdf.org/patents/pat1014719.pdf  (1912) Apparatus for Co= llecting Electrical Energy.   Or would two = or more Inv-L's spaced apart at least several tens of meters and connected together be usef= ul to get more current.
        Re Jim AA5BW said >>Sounds= like the voltage divider doesn't need to be more than a<= /div>
 >>gigohm, but perhaps for future reference: a reliable 50kV 1 terohm divider can be made
 >>very easily: encapsulate ten 100 = gigohm resistors in hard epoxy, being sure not to
 >>touch them during assembly. A single linearity calibration after curing will be remain
  = >>valid +/- 10% for years in varying humidity and temperature.  
       Jim W5EST asks:   What preamp circuit is used in the DK7FC 12.67Hz receiver?   Does it have a gigohm or terohm input impedance to less imperfectly match to the high input impedance of the atmosphere?    If not, could the design be improved = for a better match?   Would p= erhaps a 1 nF blocking capacitor C in series with a gigohm R,  with R across the gate of a preamp FET, keep atmospheric DC voltage from zapping the FET and let the FET amplify the 12.= 67Hz sinusoid.   1nF x 1 Gigoh= m =3D 1 sec. time constant so 12.67Hz would easily get through to the FET g= ate.
       I don=E2= =80=99t know if SNR would be increased, but seems like the more signal (with perhaps less noise) the = RX gets from the preamp, the better-positioned one is to apply filtering and processing to deal with low SNR.
      Re Stefan DK7FC said:  >> =E2=80=A6It causes some kind of offset, i.e. it lowers=
         =             &nb= sp;          >> the SNR difference to a signal generated by cloud charges.
      Jim W5EST comments:    Even if Stefan meant something else, his sentence got me to thinking about whether the 5KV ELF on the TX antenna per= haps offsets or diverts a tiny amount of atmospheric current entering the RX antenna. = We'd think of the atmosphere as having equipotential surface(s) high = in big mass of resistive material in which the ELF TX and RX ante= nnas are embedded circuit-wise at ground level.  In other words, maybe we could think of the 12.67Hz experiment as using the 5KV ELF at the TX antenna to very slightly periodically disturb the atmospheric currents in the RX antenna a few kilom= eters away.  Unlike Loomis, who apparently imagined a highly conductive laye= r at tropospheric altitude, we'd picture only high resi= stivity throughout a volume of calm weather troposphere .   I=E2=80=99ll try to describe= this idea quantitively in another ELF post.
GL & 73, J= im H   W5EST=
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