Return-Path: Received: from mtain-dj10.r1000.mx.aol.com (mtain-dj10.r1000.mail.aol.com [172.19.187.146]) by air-mb07.mail.aol.com (v129.4) with ESMTP id MAILINMB071-a7844d2cb0f690; Tue, 11 Jan 2011 14:35:18 -0500 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dj10.r1000.mx.aol.com (Internet Inbound) with ESMTP id 5AEF2380000A0; Tue, 11 Jan 2011 14:35:16 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Pcjyq-00035J-Vk for rs_out_1@blacksheep.org; Tue, 11 Jan 2011 19:34:08 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Pcjyq-00035A-3C for rsgb_lf_group@blacksheep.org; Tue, 11 Jan 2011 19:34:08 +0000 Received: from mail-iw0-f171.google.com ([209.85.214.171]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Pcjyn-0001vq-Er for rsgb_lf_group@blacksheep.org; Tue, 11 Jan 2011 19:34:08 +0000 Received: by iwn2 with SMTP id 2so20792507iwn.16 for ; Tue, 11 Jan 2011 11:34:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type; bh=xrvYK3/BjhRTFisUUjvd+2JFzR9eTODqsp2yw8yfePw=; b=MB5cSMX/69J9himGRUJvwmHXWIMQOLouVh1HWlpg51k1jnuVXyKPGcR55ZB0PtdUKB AbV8XV4+ZpW0oLCK1wYd7deN1aVzjLn+t5qpWraUohYhKRBC0UBeYf4cLYAjwMa4N7Va w5xc6f9C2SxZHdULW4lIeoKSFE0qHIvDLvXpk= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=MxSVFWllbj/QP9NIOg1fpa5zzaK0+UnUk2c1OEQkD+Ws4kO0+SRkAVh+vNPWWsdFP3 RorUZlVx5wJ/cf+5yea8vAuxydEADBw4Nmc8nkQ3uftbhDcdFhqNF6OGpCffMiDjrfr8 VN3jatgHzIjXR4dOrkBHmIq/ImI7VAxsC82f4= MIME-Version: 1.0 Received: by 10.42.165.5 with SMTP id i5mr6167130icy.501.1294774443928; Tue, 11 Jan 2011 11:34:03 -0800 (PST) Received: by 10.42.241.133 with HTTP; Tue, 11 Jan 2011 11:34:03 -0800 (PST) In-Reply-To: References: <4D2CA71C.5070808@iup.uni-heidelberg.de> Date: Tue, 11 Jan 2011 19:34:03 +0000 Message-ID: From: Roger Lapthorn To: rsgb_lf_group@blacksheep.org DomainKey-Status: good (testing) X-Spam-Score: 0.1 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,HTML_TAG_EXIST_TBODY=0.126 Subject: Re: LF: Re: Increased ERP on 137.5kHz - WSPR reports please Content-Type: multipart/alternative; boundary=90e6ba6e8652cb6c420499972aea X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.3 required=5.0 tests=HTML_60_70, HTML_FONTCOLOR_UNSAFE,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-m283.2 ; domain : gmail.com DKIM : pass x-aol-sid: 3039cdbc9d0f4d2cb0f46d87 X-AOL-IP: 195.171.43.25 X-Mailer: Unknown (No Version) --90e6ba6e8652cb6c420499972aea Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable The ferrite rod is tuned with a parallel capacitance of around 1400pF. The antenna is connected to the top of the tuned circuit and the antenna curre= nt meter is in series with the antenna. A 50 ohm tap point was found empirically low down the coil. 73s Roger G3XBM On 11 January 2011 19:19, Andy Talbot wrote: > If I understand corrrctly, you're measuring the current into the tap the= n? > In any case, I doubt a ferrite rod even at that power could be linear as= a > loading coil > For example :: > > Using the approximation of 6pF /metre, antenna cap =3D 18pF. Lets call > it 25pF to allows for strays. > That will need 53mH to resonate, and Xc / Xl =3D j46k ohms. > If you *were* to have 180mA flowing in the antenna, it would > therefore have around 8kV on it. > > If we assume a ferrite rod 8mm diameter, X sectional area =3D 50mm^2,= and > allow a Bmax of 0.2 Tesla > Using V =3D 4.44.F,N.A.B it will need 270 turns to avoid saturation. > Which I'm guessing it hasn't got. If it has, it'll be very thin wire th= at > can't take 8kV > > Andy > 'JNT/'IMR > > On 11 January 2011 19:04, Roger Lapthorn wrote= : > >> My Marconi is just my 28MHz halo and its short coax feed (strapped) fed >> via an indoors ferrite rod inductor which is tuned and tapped. So most= of >> the current is NOT flowing in the vertical section. I need to set to wo= rk on >> erecting a "real" vertical and a real matching network. There is no exc= use. >> >> The loop produces a signal that has been received at 148km (and quite >> consistently at 46km) despite the low ERP (recalculated as around 200uW >> based on the current flowing in the loop), so if I can get a more effec= tive >> vertical, rather than my poor attempt today, there is hope. >> >> 73s >> Roger G3XBM >> >> 2011/1/11 Stefan Sch=E4fer >> >> Roger, >>> >>> Maybe there was a kind of "utilities assisted earth mode" on the loop= at >>> 3 km distance, as you call it? How high is the antenna and where is is >>> placed? I hope its on the roof of the house :-) If its near a wet tree= and >>> just 3m long, it may be worse than the loop. How do you measure the >>> resonance? If you measure the antenna current, how high is it? >>> I think you are on the right way to make your signal detectable in hig= her >>> distances! Good luck! >>> >>> 73, Stefan/DK7FC >>> >>> Am 11.01.2011 19:26, schrieb Roger Lapthorn: >>> >>> So much for the theory then.... >>> >>> The signal level at G6ALB in the next village (3km although WSPR shows= it >>> as 0km) is some 10dB *down* on my loop antenna. Not sure if I got my >>> sums wrong or there is some unexplained loss. The RX system at G6ALB= is >>> unchanged. >>> >>> 73s >>> Roger G3XBM >>> >>> On 11 January 2011 17:32, Roger Lapthorn wrot= e: >>> >>>> Dear All, >>>> >>>> Today I rigged up and matched a simple, small, Marconi vertical on >>>> 136kHz instead of the vertical loop. Based on measurements of antenna >>>> current and some reasonable assumptions of effective height, I now be= lieve I >>>> have around 200uW ERP on the band - heck this is *high* power for me! >>>> >>>> From now until late this evening I will run the WSPR beacon (136kHz= USB >>>> dial) in the hope that a few more people will be able to copy the QRP= p >>>> signal. Please have a go and let me have any reports. >>>> >>>> 73s and good luck >>>> >>>> Roger G3XBM >>>> >>>> -- >>>> g3xbm-qrp.blogspot.com/ >>>> www.g3xbm.co.uk >>>> www.youtube.com/user/g3xbm >>>> G3XBM GQRP 1678 ISWL G11088 >>>> >>> >>> >>> >>> -- >>> g3xbm-qrp.blogspot.com/ >>> www.g3xbm.co.uk >>> www.youtube.com/user/g3xbm >>> G3XBM GQRP 1678 ISWL G11088 >>> >>> >>> >>> >>> >>> >> >> >> -- >> g3xbm-qrp.blogspot.com/ >> www.g3xbm.co.uk >> www.youtube.com/user/g3xbm >> G3XBM GQRP 1678 ISWL G11088 >> >> >> = >> > > --=20 g3xbm-qrp.blogspot.com/ www.g3xbm.co.uk www.youtube.com/user/g3xbm G3XBM GQRP 1678 ISWL G11088 <#> <#> <#> <#> --90e6ba6e8652cb6c420499972aea Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable The ferrite rod is tuned with a parallel capacitance of around 1400pF. The= antenna is connected to the top of the tuned circuit and the antenna curr= ent meter is in series with the antenna. A 50 ohm tap point was found empi= rically low down the coil.

73s
Roger G3XBM

On 11 January 2011 19:19, Andy Talbot <andy.g4jnt@gmail.com> wro= te:
If I under= stand corrrctly, you're measuring the current into the tap then?
In any case, I doubt a ferrite rod even at that power could be linear= as a loading coil
For example=A0::
=A0
Using the approximation of 6pF /metre, antenna cap =3D 18pF.=A0 Lets= call it=A025pF to allows for strays.=A0=A0
That will need 53mH to resonate, and Xc / Xl =3D=A0 j46k ohms.=A0=A0= =A0=A0=A0
If you were to have 180mA flowing in the antenna, it would the= refore=A0have around 8kV on it.=A0
=A0
If we assume a ferrite rod 8mm diameter,=A0 X sectional area=A0=3D 50= mm^2, and allow a Bmax of 0.2 Tesla
Using V =3D 4.44.F,N.A.B=A0=A0it will=A0need 270 turns to avoid satur= ation.=A0=A0=A0
Which I'm guessing it hasn't got.=A0 If it has, it'll be= very thin wire that can't take 8kV
=A0
Andy
'JNT/'IMR

On 11 January 2011 19:04, Roger Lapthorn <rogerlapthorn@gmail.com> wrote:
My Marconi is= just my 28MHz halo and its short coax feed (strapped) fed via an indoors= ferrite rod inductor which is tuned and tapped. So most of the current is= NOT flowing in the vertical section. I need to set to work on erecting a= "real" vertical and a real matching network. There is no excuse= .

The loop produces a signal that has been received at 148km (and quite= consistently at 46km) despite the low ERP (recalculated as around 200uW= based on the current flowing in the loop), so if I can get a more effecti= ve vertical, rather than my poor attempt today, there is hope.

73s
Roger G3XBM

2011/1/11 Stefan Sch= =E4fer <schaefer@iup.uni-heidelberg.de>=20

Roger,

Maybe there was a= kind of=A0 "utilities assisted earth mode" on the loop at 3 km= distance, as you call it? How high is the antenna and where is is placed?= I hope its on the roof of the house :-) If its near a wet tree and just= 3m long, it may be worse than the loop. How do you measure the resonance?= If you measure the antenna current, how high is it?
I think you are on the right way to make your signal detectable in higher= distances! Good luck!

73, Stefan/DK7FC

Am 11.01.2011 19:26,= schrieb Roger Lapthorn:=20
So much for the theory then....

The signa= l level at G6ALB in the next village (3km although WSPR shows it as 0km)= is some 10dB down on my loop antenna. Not sure if I got my sums wr= ong or there is some unexplained loss. The RX system at G6ALB is unchanged= .

73s
Roger G3XBM

On 11 January 2011 17= :32, Roger Lapthorn <rogerlapthorn@gmail.com> wrote:=
Dear All,
Today I rigged up and matched a simple, small, Marconi vertical on 136kH= z instead of the vertical loop. Based on measurements of antenna current= and some reasonable assumptions of effective height, I now believe I have= around 200uW ERP on the band - heck this is high power for me!

From now until late this evening I will run the WSPR beacon (136kHz US= B dial) in the hope that a few more people will be able to copy the QRPp= signal. Please have a go and let me have any reports.

73s and good= luck

Roger G3XBM

--
g3xbm-qrp.blogspot.= com/
www.g3xb= m.co.uk
www.youtub= e.com/user/g3xbm
G3XBM=A0=A0 GQRP 1678=A0=A0=A0 ISWL G11088



--
g3xbm-qrp.blogspot.com/
www.g3xbm.co.uk<= br>www.you= tube.com/user/g3xbm
G3XBM=A0=A0 GQRP 1678=A0=A0=A0 ISWL G11088
<= /table>
3D""
=
=A0 =A0

=A0
3D"" =A0 3D"" =A0 =A0 =A0
=
=A0
=A0

=






--
g3xbm-qrp.blogspot.com/
www.g3xbm.co.uk
www.youtube.com/user/g3xb= m
G3XBM=A0=A0 GQRP 167= 8=A0=A0=A0 ISWL G11088
<= /table>
3D""
=
=A0 =A0
=A0
3D"" =A0 3D"" =A0 =A0 =A0
=
=A0
=A0




--
g3xbm-qrp.blogspot.com/=
www.g3xbm.co.= uk
www.youtub= e.com/user/g3xbm
<= /a>G3XBM=A0=A0 GQRP 1678=A0=A0=A0 ISWL G11088
= 3D""
=20 =20
=A0 =A0
=20
=A0
3D"" =A0 3D"" =A0 =A0 =A0
=20
=A0
=A0
=20 =20 =20
=20 =20 =20 = =20
= =20
=20
=20
--90e6ba6e8652cb6c420499972aea--