Return-Path: Received: from mtain-mj07.r1000.mx.aol.com (mtain-mj07.r1000.mail.aol.com [172.21.164.91]) by air-ma07.mail.aol.com (v127_r1.1) with ESMTP id MAILINMA074-b52f4b865c7088; Thu, 25 Feb 2010 06:18:08 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-mj07.r1000.mx.aol.com (Internet Inbound) with ESMTP id B096A380000DA; Thu, 25 Feb 2010 06:18:04 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Nkbhy-00023p-9A for rs_out_1@blacksheep.org; Thu, 25 Feb 2010 11:16:42 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Nkbhx-00023g-H5 for rsgb_lf_group@blacksheep.org; Thu, 25 Feb 2010 11:16:41 +0000 Received: from smtp829.mail.ukl.yahoo.com ([217.12.13.164]) by relay1.thorcom.net with smtp (Exim 4.63) (envelope-from ) id 1Nkbhv-0003Ss-J9 for rsgb_lf_group@blacksheep.org; Thu, 25 Feb 2010 11:16:41 +0000 Received: (qmail 38770 invoked from network); 25 Feb 2010 11:16:33 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=btinternet.com; h=DKIM-Signature:Received:X-Yahoo-SMTP:X-YMail-OSG:X-Yahoo-Newman-Property:Message-ID:From:To:References:Subject:Date:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:X-MIMEOLE; b=qyvZObmnP3mEv+CN1JB0OZgjz7FDLhLCCSS+VIA/cjYbAAguVgDPXxtUon3+0cHDbNVhFaLdupo9gBzM4VE7Dr7Ex7rlXzN3wmLKJeK1rI1wctCErSXxsFDZALqTai1P4/yc6eJhNt78k5cn3noY/azcEHg7Bli7Hl57Ct2NUlE= ; DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=btinternet.com; s=s1024; t=1267096593; bh=QAxzBilUcwPl6epBiF6pBXE4hzt3U0smhBftZlXl43s=; h=Received:X-Yahoo-SMTP:X-YMail-OSG:X-Yahoo-Newman-Property:Message-ID:From:To:References:Subject:Date:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:X-MIMEOLE; b=V+GmbDXjGNTkamaApn3wXCHk/Jku1cABMVUna2zRpqVF2jJGZH+d7O7zo/6/ej48xJ+o+7fXvA+nz9pWKnQSj3TSSmmA4adKtUzt4OJuU28T8QwxMFdQltL1Pmga3iFrWFDDUDYFsGJFxQwSFudfPxDomHgAk4BIH4kuCS1qIUg= Received: from IBM7FFA209F07C (c.ashby435@86.169.135.218 with login) by smtp829.mail.ukl.yahoo.com with SMTP; 25 Feb 2010 11:16:33 +0000 GMT X-Yahoo-SMTP: .u8e2g.swBByWKjbpA3lR6Fw.2ZEQrJJpVsTSrpXLCffsPaCEMY- X-YMail-OSG: PpLXYJkVM1nP_Cldbxs4G16NBpzWjQjqljjka1m4uBLy4jc1yzZfCYNE9zoIa.3QW2KMImqtlKhmQviaumd63MXvdLJ6dSgdeNl3YrHbufmJHQJmVID7oLkZfY_OI7nOy8fQ9zwStb2PKPV7qxOX156Wo47EpkmKkGm7xzulWYZ7I8P11Qp.NQMeQW8ji0ti42u0vgnU91TiPe9Cj.fyYeAXEHbAaU1x3E4mv.O8XuoKtS1viQ-- X-Yahoo-Newman-Property: ymail-3 Message-ID: <72058C74D1E84593AE608BA4ED0E2297@IBM7FFA209F07C> From: "Chris" To: References: <818138.8525.qm@web28102.mail.ukl.yahoo.com> Date: Thu, 25 Feb 2010 11:16:33 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5843 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 DomainKey-Status: good (testing) X-Spam-Score: 3.5 (+++) X-Spam-Report: autolearn=disabled,FORGED_MUA_OUTLOOK=3.36,HTML_MESSAGE=0.001,HTML_TAG_EXIST_TBODY=0.126,UNPARSEABLE_RELAY=0.001 Subject: Re: LF: RE: Re: VLF_8.79 kHz Content-Type: multipart/alternative; boundary="----=_NextPart_000_001B_01CAB60B.FCF26540" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: ** X-Spam-Status: No, hits=2.6 required=5.0 tests=FORGED_MUA_OUTLOOK, FROM_ENDS_IN_NUMS,HTML_MESSAGE,HTML_TAG_EXISTS_TBODY 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-AUTHENTICATION: mail_rly_antispam_dkim-d221.2 ; domain : btinternet.com DKIM : pass x-aol-sid: 3039400c89ae4b865c6c7118 X-AOL-IP: 193.82.116.20 ------=_NextPart_000_001B_01CAB60B.FCF26540 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable You should NEVER 'stick an antenna wire into your sound card'. Chris, G4AYT, Whitstable, Kent. ----- Original Message -----=20 From: M0FMT=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Thursday, February 25, 2010 10:38 AM Subject: Re: LF: RE: Re: VLF_8.79 kHz Ken. Why not just stick an antenna wire into your Sound card mic so= cket and install either Argo Spectran or Spec lab FFT application. You= then have DC to 48kc/s VLF coverage with the ability to detect very= very weak signals. Using SDR software you can then record the result= in real time spectrum allowing it to be processed by others.=20 This type of set up is used by many people to copy SAQ on 17.2= kc/s. It is the method we are using here for some simple tests on 7.= 8125kc/s and or 9.765625kc/s depending upon xtal used.=20 You are about 11km from this location if you are keen on this= exercise I can let you know when my setup is working. Now that the we= ather is getting better I will be able to get out working on the anten= na. Two arrangements will be tried a vertical loop up abt 12/13m= and an earth electrode method. I have no real idea of how to load the= se antennas because my best calculations say if I use a kW the coil ab= out 1 Henry will dissipate most of the power which means it be getting= very very hot and probably fail and need over 2 km of wire. Totally= impractical! Some ideas have been kicked around on the is reflector= and off list there may be something I can try. 73 es GL petefmt --- On Thu, 25/2/10, Ken wrote: From: Ken Subject: LF: RE: Re: VLF_8.79 kHz To: rsgb_lf_group@blacksheep.org Date: Thursday, 25 February, 2010, 10:05 Hi Jim. I think I could knock up a quick 9kHz RX here in Luton over= the weekend if that would help. I have been following this thread with inte= rest, could you put up some diagrams etc of your parallel capacitor and othe= r antenna configurations and formulae. 73. Ken M0KHW IO91TV -----Original Message----- From: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Jam= es Moritz Sent: 24 February 2010 21:14 To: rsgb_lf_group@blacksheep.org Subject: LF: Re: VLF_8.79 kHz Dear LF Group, A couple of years ago I did some measurements of Rloss of th= e 10m high, 40m=20 long inv-L antenna at my home QTH, and also a near-identical= antenna set up=20 in the middle of a field away from trees and buildings. The= attached graph=20 shows Rloss plotted against frequency over the range 10kHz= to 600kHz for=20 both antennas. At all frequencies, the loss resistance of th= e open-field=20 antenna is much lower than the home QTH antenna, which is su= rrounded by=20 numerous small trees. The ground in both cases was 4 x 1m gr= ound rods, close to the feed point of the antenna. The actual ground around= both antennas was very similar - a waterlogged clay soil. At 10kHz, the open field antenna has Rloss of 50R, against= 380R for the=20 home QTH antenna. Both antennas show a decreasing Rloss with= frequency -=20 this suggests dielectric losses are dominant (the antenna vo= ltage increases=20 at lower frequencies for a given current) in both cases. The= text books say, for electrically small antennas, that dielectric losses will= dominate at low frequencies, while at high frequencies the skin effect will= eventually cause resistance to start increasing - in the case of the open fie= ld antenna, a=20 turn-over point might have been reached at a few hundred kHz= . The 50R figure suggests that antenna efficiency might actual= ly be higher at=20 9kHz than people are expecting - at least in an open field= site. A suitable=20 loading coil would be a problem. The antenna capacitance was= around 350pF -=20 in these experiments I used a ferrite-cored coil of around= 0.7H with a Q of=20 about 150, but this had a loss resistance of about 300R. If= you tolerated=20 loosing half the TX power in the loading coil, a similar ind= uctance with a Q of around 1000 would be needed. Increasing the top-loading= capacitance of=20 the antenna would definitely be useful... Cheers, Jim Moritz 73 de M0BMU =20 ------=_NextPart_000_001B_01CAB60B.FCF26540 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
You should NEVER 'stick an antenna wi= re into your=20 sound card'.
Chris, G4AYT, Whitstable, Kent.
----- Original Message -----
From:=20 M0FMT=
Sent: Thursday, February 25,= 2010 10:38=20 AM
Subject: Re: LF: RE: Re: VLF_= 8.79=20 kHz


------=_NextPart_000_001B_01CAB60B.FCF26540--
Ken.
Why not just stick an antenna wire into your Sound card= mic socket=20 and install either Argo Spectran or Spec lab FFT= =20 application. You then have DC to 48kc/s VLF coverage with the= ability to=20 detect very very weak signals. Using SDR software you can then= record=20 the result in real time spectrum allowing it to be processed= by others.=20

This type of set up is used by many people to copy SA= Q on=20 17.2kc/s.
 
It is the method we are using here for some simple tests= on=20 7.8125kc/s and or 9.765625kc/s depending upon xtal used.
 
You are about 11km from this location if you are keen on= this=20 exercise I can let you know when my setup is working. Now that= the=20 weather is getting better I will be able to get out worki= ng on the=20 antenna.
 
Two arrangements will be tried a vertical loop up a= bt=20 12/13m and an earth electrode method. I have no real idea of= how to load=20 these antennas because my best calculations say if I use a kW= the coil=20 about 1 Henry will dissipate most of the power which means it= =20 be getting very very hot and probably fail and need over= 2 km of=20 wire. Totally impractical! Some ideas have been kicked ar= ound on=20 the is reflector and off list there may be something I can try= .

73 es GL petefmt

--- On Thu,= 25/2/10,=20 Ken <ken.h.wright@btinternet.com> wrote:
<= /DIV>

From:=20 Ken <ken.h.wright@btinternet.com>
Subject: LF: RE:= Re:=20 VLF_8.79 kHz
To: rsgb_lf_group@blacksheep.org
Date: Th= ursday, 25=20 February, 2010, 10:05

Hi Jim.
I think I could knock up= a quick 9kHz=20 RX here in Luton over the weekend if
that would help. I= have been=20 following this thread with interest, could you
put up som= e diagrams=20 etc of your parallel capacitor and other antenna
configur= ations and=20 formulae.

73.
Ken
M0KHW   =20 IO91TV

-----Original Message-----
From: owner-rsgb_lf_group@blacksheep.org
[mai= lto:owner-rsgb_lf_group@blacksheep.org= ]=20 On Behalf Of James Moritz
Sent: 24 February 2010 21:14To: rsgb_lf_group@blacksheep.org
Subject:= =20 LF: Re: VLF_8.79 kHz

Dear LF Group,

A couple= of years=20 ago I did some measurements of Rloss of the 10m high, 40m long=20 inv-L antenna at my home QTH, and also a near-identical ante= nna set up=20
in the middle of a field away from trees and buildings.= The=20 attached graph
shows Rloss plotted against frequency ove= r the=20 range 10kHz to 600kHz for
both antennas. At all frequenc= ies, the=20 loss resistance of the open-field
antenna is much lower= than the=20 home QTH antenna, which is surrounded by
numerous small= trees. The=20 ground in both cases was 4 x 1m ground rods, close

to= the feed=20 point of the antenna. The actual ground around both antennas= =20 was

very similar - a waterlogged clay soil.

At= 10kHz,=20 the open  field antenna has Rloss of 50R, against 380R= for the=20
home QTH antenna. Both antennas show a decreasing Rloss= with=20 frequency -
this suggests dielectric losses are dominant= (the=20 antenna voltage increases
at lower frequencies for a giv= en=20 current) in both cases. The text books say,

for elect= rically=20 small antennas, that dielectric losses will dominate at=20 low

frequencies, while at high frequencies the skin= effect will=20 eventually cause

resistance to start increasing - in= the case=20 of the open field antenna, a
turn-over point might have= been=20 reached at a few hundred kHz.

The 50R figure suggests= that=20 antenna efficiency might actually be higher at
9kHz than= people=20 are expecting - at least in an open field site. A suitable=
loading=20 coil would be a problem. The antenna capacitance was around= 350pF -=20
in these experiments I used a ferrite-cored coil of arou= nd 0.7H=20 with a Q of
about 150, but this had a loss resistance of= about=20 300R. If you tolerated
loosing half the TX power in the= loading=20 coil, a similar inductance with a Q

of around 1000 wo= uld be=20 needed. Increasing the top-loading capacitance of
the an= tenna=20 would definitely be useful...

Cheers, Jim Moritz
7= 3 de=20 M0BMU