Return-Path: Received: from mtain-md01.r1000.mx.aol.com (mtain-md01.r1000.mx.aol.com [172.29.96.85]) by air-mc07.mail.aol.com (v127_r1.1) with ESMTP id MAILINMC071-a97b4bad2bb39a; Fri, 26 Mar 2010 17:48:35 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-md01.r1000.mx.aol.com (Internet Inbound) with ESMTP id 166A1380000B4; Fri, 26 Mar 2010 17:48:28 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NvHMx-0004u5-NK for rs_out_1@blacksheep.org; Fri, 26 Mar 2010 21:47:07 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NvHMx-0004to-5q for rsgb_lf_group@blacksheep.org; Fri, 26 Mar 2010 21:47:07 +0000 Received: from mail-bw0-f215.google.com ([209.85.218.215]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NvHMu-0001FJ-Sp for rsgb_lf_group@blacksheep.org; Fri, 26 Mar 2010 21:47:07 +0000 Received: by bwz7 with SMTP id 7so4768365bwz.4 for ; Fri, 26 Mar 2010 14:46:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:received:message-id:subject:from:to:content-type; bh=650yPUsn/SXxeOFz2423a5FIRBZ0ioKsw5jnq2eDxdI=; b=fGg5cp0RQ6ea0ehHsCTpPgIypxNWLjronlGE2mBtPTMvOLtc97s9Di4fYozUrulghA 6iSaJvTaY9mWppWGVXPhWkmfYT9cfM+g2ECpSuUVnewQall6abCedIIcPxyWmW77wyfM iZCvnLH/Jbn/X7MVwrujgBYD6Fn94ow/CBfU4= DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=AGxkHrssUqEl7gy3K0AqWaaCqwsnHl9LYD2OMK183ShqsoUpHix9HUUJsarIyweKAi NC3RSh0EppTM6OtGEb3eYu/M1P68BjLO87whHl5YSq6fTcONGcMg3El1pV0imV6Dbpzb m1/12QFKkUuWjhJ5uvTmNJC7oRnQkLVTIN5ok= MIME-Version: 1.0 Received: by 10.204.65.79 with HTTP; Fri, 26 Mar 2010 14:46:58 -0700 (PDT) In-Reply-To: <002501cacd29$da3eea70$0901a8c0@lark> References: <4BAD19D0.300@telia.com> <002501cacd29$da3eea70$0901a8c0@lark> Date: Fri, 26 Mar 2010 21:46:58 +0000 Received: by 10.204.33.215 with SMTP id i23mr2409403bkd.86.1269640018411; Fri, 26 Mar 2010 14:46:58 -0700 (PDT) Message-ID: From: Andy Talbot To: rsgb_lf_group@blacksheep.org DomainKey-Status: good (testing) X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: Question about ground impedance at 8.97 KHZ Stefan. Content-Type: multipart/alternative; boundary=0003255558f64a3fd00482bb1af8 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=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 x-aol-global-disposition: G X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-d265.2 ; domain : googlemail.com DKIM : pass x-aol-sid: 3039ac1d60554bad2bac407f X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --0003255558f64a3fd00482bb1af8 Content-Type: text/plain; charset=ISO-8859-1 I wondered that, but 500pF as measured, if genuine at 10kHz, works out at -j 32000, which is close to the 70k Real term. The series equivalents are therefore 12k - j26.5k - which still doesn't seem right. Andy www.g4jnt.com On 26 March 2010 20:48, Alan Melia wrote: > Hi Johan, an Impedance bridge measures the reactance and resistance is > parallel I believe....doe sthat make a difference to what he is seeing?? > > Alan G3NYK > > ----- Original Message ----- > From: "Johan H. Bodin" > To: > Sent: Friday, March 26, 2010 8:32 PM > Subject: Re: LF: Question about ground impedance at 8.97 KHZ Stefan. > > > > Hi Paul, > > > > it sounds like your impedance bridge is measuring the absolute impedance > > (that is Z = (R^2 + X^2)^0.5 where R is the real part, resistance, and X > > is the imaginary part, reactance). R is probably a 10 to a few hundred > > ohms, most of it is ground resistance - it can be neglected - the major > > part of your impedance is the capacitive reactance of the antenna (Xc). > > At 9 kHz, where C = 1/(2*Pi*9000*Xc), 70 kOhms means 253pF which is in > > the ballpark for your 170' wire (about 5pF/m). > > > > 73 > > Johan SM6LKM > > > > ---- > > > > Paul A. Cianciolo wrote: > > > > > > Hello All, > > > > > > Below is a quote from the Stefan's web page concerning his latest > "Dreamers Band" DX contact Congratulations again Stefan. > > >>From this information alone is it possible to calculate or know the > antenna system impedance. > > > > > > > > > > > > > > > "100m Vertical wire antenna, coil/antenna voltage was abt 15kV rms, > average antenna current about 480mA, giving up to 1,7mW ERP. Applied power > was up to 250W." > > > > > > Pertaining to the coil "Technical and mechanical data: L=553mH, Q=82, > R(DC)=283 Ohm; 0,4mm diameter enameled copper wire, about 1200 turns! > Average diameter 0,55m, height abt 0,5m. So, about 2000m wire! :-)" > > > > > > > > > > > > I have built a small impedance bridge that operates at 10 KHZ and shows > my sloping 170' wire as 70K Ohms. I can also see approx 500 PF that can be > nulled out using the bridge? > > > > > > Can the 70K value possibly be correct? (3) 6' ground rods about 6' > apart are the ground... plus the electrical ground of the house. > > > > > > I am hoping to attempt a local transmission on 9KHZ > > > > > > Any information would be helpful. > > > > > > Thank you > > > > > > Paul > > > > > > W1VLF > > > > > > > > > > > > > > > > > > > > --0003255558f64a3fd00482bb1af8 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
I wondered that, but 500pF as measured, if genuine at 10kHz, works ou= t at -j 32000, which is close to the 70k Real term.=A0=A0 The series equiv= alents are therefore 12k - j26.5k=A0 -=A0=A0 which still doesn't seem= right.
=A0
On 26 March 2010 20:48, Alan Melia <alan.melia@btintern= et.com> wrote:
Hi Johan, an Impedance bridge= measures the reactance and resistance is
parallel I believe....doe sth= at make a difference =A0to what he is seeing??

Alan G3NYK

----- Original Message -----
From: "Johan H.= Bodin" <jh.bodin@telia.com<= /a>>
To: <rsgb_lf= _group@blacksheep.org>
Sent: Friday, March 26, 2010 8:32 PM
Subject: Re: LF: Question about gr= ound impedance at 8.97 KHZ Stefan.


> Hi Paul,
>
>= ; it sounds like your impedance bridge is measuring the absolute impedance=
> (that is Z =3D (R^2 + X^2)^0.5 where R is the real part, resistance,= and X
> is the imaginary part, reactance). R is probably a 10 to a= few hundred
> ohms, most of it is ground resistance - it can be neg= lected - the major
> part of your impedance is the capacitive reactance of the antenna (Xc= ).
> At 9 kHz, where C =3D 1/(2*Pi*9000*Xc), 70 kOhms means 253pF wh= ich is in
> the ballpark for your 170' wire (about 5pF/m).
&g= t;
> 73
> Johan SM6LKM
>
> ----
>
> Paul A. Cianciolo wrote:
> >
&g= t; > Hello All,
> >
> > Below is a quote from the Ste= fan's web page concerning his latest
"Dreamers Band" DX= contact Congratulations again Stefan.
> >>From this information alone is it possible to calculate or kn= ow the
antenna system impedance.
> >
> >
> >=
> >
> > "100m Vertical wire antenna, coil/antenna= voltage was abt 15kV rms,
average antenna current about 480mA, giving up to 1,7mW ERP. Applied power=
was up to 250W."
> >
> > Pertaining to the coil= "Technical and mechanical data: L=3D553mH, Q=3D82,
R(DC)=3D283 Oh= m; 0,4mm diameter enameled copper wire, about 1200 turns!
Average diameter 0,55m, height abt 0,5m. So, about 2000m wire! :-)"> >
> >
> >
> > I have built a small im= pedance bridge that operates at 10 KHZ and shows
my sloping 170' wi= re as 70K Ohms. I can also see approx 500 PF that can be
nulled out using the bridge?
> >
> > Can the 70K value= possibly be correct? =A0 (3) 6' ground rods about 6'
apart are= the ground... plus the electrical ground of the house.
> >
&g= t; > I am hoping to attempt a local transmission on 9KHZ
> >
> > Any information would be helpful.
> >
&= gt; > Thank you
> >
> > Paul
> >
> >= ; W1VLF
> >
> >
> >
> >
> > >



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