Return-Path: Received: from mtain-dj10.r1000.mx.aol.com (mtain-dj10.r1000.mail.aol.com [172.19.187.146]) by air-mb03.mail.aol.com (v129.4) with ESMTP id MAILINMB034-a21f4bfae79e39; Mon, 24 May 2010 16:54:54 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-dj10.r1000.mx.aol.com (Internet Inbound) with ESMTP id E20F338000A2F; Mon, 24 May 2010 16:54:52 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OGeej-00073k-73 for rs_out_1@blacksheep.org; Mon, 24 May 2010 21:53:49 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OGeei-00073b-7V for rsgb_lf_group@blacksheep.org; Mon, 24 May 2010 21:53:48 +0100 Received: from mail-bw0-f43.google.com ([209.85.214.43]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1OGeeg-0008MK-47 for rsgb_lf_group@blacksheep.org; Mon, 24 May 2010 21:53:48 +0100 Received: by bwz16 with SMTP id 16so1239273bwz.16 for ; Mon, 24 May 2010 13:53:45 -0700 (PDT) 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=J2atwowiqUf7MEwOfjLs3eP7GYwAOw3qf0IMT8yGgxc=; b=E/deCmaXSaZR5z8qUED9R3C4M2vgd74FuSVx0q+MZCeiJXcqOmuGe4QY7QFCwOLn7H hsS2zQsWpWvFYbVYLSC0f6nKDHyXH2nOBCjs2WV7Dfe79rB1I1EQpCgZIc8YbFJtPa99 33ZJ7x8SwFf5xS6LmiONoFJqubei6BBC0XfDk= 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=YM1DuEiGgjeVfDlkdcJRf80OyURfUWBZqKfPjSOKdoTYFXHQdqXXISEvmkT1HrranL EbvM7F7Wlz/ftJmULZuQbluZHfBW1oWpWalJ+OVjygLbPglKqv+yBGFcqlUSbhw6coEU dJyi+jK5jZGVUJs+CenO+HOoCjgSziZs/HG+o= MIME-Version: 1.0 Received: by 10.204.4.194 with SMTP id 2mr2446890bks.53.1274734425100; Mon, 24 May 2010 13:53:45 -0700 (PDT) Received: by 10.204.58.204 with HTTP; Mon, 24 May 2010 13:53:45 -0700 (PDT) In-Reply-To: References: <38A51B74B884D74083D7950AD0DD85E82A1C00@File-Server-HST.hst.e-technik.tu-darmstadt.de> <315092772.1763254.1274721526409.JavaMail.fmail@mwmweb035> Date: Mon, 24 May 2010 21:53:45 +0100 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: AW: 8.97kHz - Near field and radiated signals? Content-Type: multipart/alternative; boundary=0015174bf27497521b04875d3c12 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.6 required=5.0 tests=HTML_20_30,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-m244.1 ; domain : gmail.com DKIM : pass x-aol-sid: 3039cdbc9d0f4bfae79c3214 X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --0015174bf27497521b04875d3c12 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Yes Rik, my current earth-mode tests are around 1kHz so the signal is audible in my crystal earpiece. My TX consists of a TDA2003 fed by a 1kHz oscillator keyed every second, so I hear a distinctive "beep, beep, beep..." at the RX end. I measured the DC resistance between the (original) TX electrodes as aroun= d 40-60 ohms and I use a toroidal step-up transformer to achieve rough matching. At the RX end the loop is untuned. When using an up-converter or direct conversion receiver (such as M0BMUs) I will try at 8.97kHz as well.= I still have a LOT to do to optimise the receive system before I try QRSS or WSPR to extend range. It's all basic, low tech, stuff but it is such fun, HI. 73s Roger G3XBM On 24 May 2010 21:37, Rik Strobbe wrote: > Hello Roger, > > interesting. > Did I read it correct that your transmit frequency is 1kHz instead of 9k= Hz > ? > I gues that also ground antennas become more efficient at higher > frequencies. > How did you match the antenna ? > > 73, Rik ON7YD - OR7T > > ------------------------------ > *Van:* owner-rsgb_lf_group@blacksheep.org [ > owner-rsgb_lf_group@blacksheep.org] namens Roger Lapthorn [ > rogerlapthorn@gmail.com] > *Verzonden:* maandag 24 mei 2010 22:28 > *Aan:* rsgb_lf_group@blacksheep.org > *Onderwerp:* Re: LF: AW: 8.97kHz - Near field and radiated signals? > > Attached is a map showing how far I managed on 1kHz earth mode this > evening. Green is strong RS56 signals and orange is just copied RS33 > signals, by ear. TX power 4W + 20m base electrodes, RX 80cm loop. > > 73s > Roger G3XBM > > On 24 May 2010 20:36, Roger Lapthorn wrote: > >> Thanks Horst. >> >> I'll try a Marconi antenna at some point, although my space is limited= to >> little more than the antenna I used on 500kHz (a top loaded 5m vertical= ). >> >> This evening I extended the TX electrode spacings by connecting one end= to >> the copper pipes in the house, almost doubling the effective TX baselin= e to >> about 20m. With this, my "earth mode" signals were *much* stronger and= I >> was able to cover further than before in a "by ear" walk-about test aro= und >> the fields. Ultimate range tonight was 0.4kms using 4W (probably less= as >> the TDA2003 was hot and probably turning down the power) and receiving= on an >> 80cm loop. active HPF, small AF amp and crystal earpiece. Range was li= mited >> by 50Hz mains hum and background sferic noise. I must try this set-up= with >> my HF up-converter and FT817 this week which has good rejection of 50Hz >> (and its harmonics) mains hum and a narrow CW filter. >> >> 73s >> Roger G3XBM >> >> >> >> >> On 24 May 2010 18:18, Horst St=F6cker wrote: >> >>> Hello Roger, Dreamers, >>> if we define near field as < 2 lambda we are talking about everything >>> below 60 km.With this distance I woul be extremely lucky. >>> I also do "walkaround tests" near my garden. But I bet only in the fla= t >>> field one can see what is possible with small antenna an without a big >>> loading coil. >>> Out from my garden I tried my 10h/20t Marconi as well as a 30m earth >>> base. The Marconi worked better, but not good enough. A TV transformer= (must >>> be flyback of course) made it much better. >>> But all the trees and houses are coupling the radiated signal to earth >>> and also the AATIS-RX is very much influenced by them. >>> I also assume that the horinontal parts of a wire do the same. So only= a >>> vertical should work. >>> For operation in city environment smaller antennas at the roof top (ol= d >>> CB antennas) will possibly work better than the bigger vertical in my= garden >>> between trees and houses at ground level. It might be worth a test. >>> One of the next tests will be with my gig earth base. I have collected >>> about 800m of surplus wire. Possibly this is another way to even radia= te >>> more then near field. But I would be very surprised it this was good= for any >>> DX. >>> I bet Stefans kite antenna will at least be the only way to DX operati= on. >>> Unfortunately this is just portable and just temporary. >>> vy73 Horst DO1KHS/DI2AN >>> >>> ------------------------------ >>> *Von:* Roger Lapthorn >>> *Gesendet:* 24.05.2010 18:36:28 >>> >>> *An:* rsgb_lf_group@blacksheep.org >>> *Betreff:* Re: LF: AW: 8.97kHz - Near field and radiated signals? >>> >>> >>> Thank you for your fast reply Stefan. >>> >>> In answer to your questions: >>> >>> - Currently, my *TX electrode spacing is 10m*, which is the best I >>> can manage in my small garden. Both electrodes are as far away from= the >>> mains and other utility services as I can manage. >>> - I have *not tried /P* transmit testing yet. >>> - My *nearest ham who will listen/look is 3kms away*, but using >>> beaconing I am able to go out myself and see how far I can reach.= This is >>> what I have done so far, going out into the fields behind my house= with >>> electrode pairs or a loop receiver. Best (by ear reception) DX is= 0.35kms, >>> but the system has much scope for optimisation still. >>> - The largest single turn loop I could erect in my garden would be >>> about 50-70 sq m (about 15m top and 4m-5m high). The longest antenn= a length >>> would also be 15m horizontal with some vertical section(s) too. >>> - The best DX targets are quite modest: I would like to exceed 1km >>> initially with the TX power I currently have (around 4W). If I coul= d reach >>> G6ALB in the next village 3kms away I would be delighted. If I got= any >>> further I would be both amazed and VERY happy! >>> >>> 73s >>> Roger G3XBM >>> >>> >>> 2010/5/24 Stefan Sch=E4fer >>> >>>> Hello Roger, >>>> >>>> For your ground electrodes, ground electrodes may be the best "antenn= a" >>>> in some 10...10m. I'm not sure how to calculate field strengths but= i just >>>> know about the 1/d^3 dependency, so twice the distance means 8 times= the >>>> power for the same signal reception, in the near field. But it is the >>>> question what are the electrodes since there is ever a coupling to th= e mains >>>> earth and all the metallic stuff in regions where people are living= so this >>>> dependency might not be valid in your tests. As mentioned here, you= could >>>> benefit from these conductors... >>>> >>>> But if you want to reach more distance with an antenna of the same si= ze >>>> (e.g. of your garden)and the same power, you could try such a TV >>>> transformer. Take a wire, as long as possible and as high as possible= , and >>>> apply some kV on it by this transformer. It can even be resonated by >>>> adjusting the air gap between the both ferrite parts. That results in= a >>>> maximum output voltage and thus "ERP". At least this would be a good >>>> alternative to your ground electrode tests. You could easily compare= the >>>> reachable distances. Here i would use a E field antenna for reception= in the >>>> near field. >>>> >>>> How far is your next receiving amateur radio station away? And have= you >>>> tried to do such tests outside the village/city, just like Jim does= it with >>>> his loop antenna? This could allow you to increase the distance of yo= ur >>>> reception. Here, space is not limited and you could try 2x10m, 2x50m,= 2x100m >>>> and so on and tell us the difference in the feed point impedance at= various >>>> frequencies and your ODX :-) Maybe i will also do some ground electro= de >>>> tests in summer but i am still not sure. The complete receiver of Jim= is a >>>> really good idea to check the QRM situation at a given QTH. Probably= i will >>>> also buit his loop design for such tests... Would be interesing what= is the >>>> maximum distance for a CW reception of my transmitted signal (with th= e kite >>>> antenna and 6mW ERP) ;-) >>>> >>>> I will also do some near field tests in this week, to compare the >>>> performance of my 2 grabbers. This will be done here: >>>> http://www.google.de/maps?f=3Dq&source=3Ds_q&hl=3Dde&geocode=3D&q=3Dh= eiligenberg+heidelberg&sll=3D47.820666,9.312449&sspn=3D0.106733,0.219383&g= =3Dheiligenberg&ie=3DUTF8&hq=3D&hnear=3DHeiligenberg&ll=3D49.419391,8.7041= 01&spn=3D0.001616,0.003428&t=3Dh&z=3D18in about 1,8km distance to my grabb= ers. Power will also be below 100W and >>>> the antenna wire will be mounted on a tower in abt 15m height. I will >>>> transmit with this TV transformer on a 40m wire. >>>> >>>> Roger, what size is your garden? What is the maximum wire length that >>>> you can apply and in which height? What is your goal (best DX, a real= s QSO >>>> with the next equipped station or just do some funny tests?) >>>> >>>> So, wish you fun and success with your experiments! >>>> >>>> 73, Stefan/DK7FC >>>> >>>> PS: What is your locator / QTH? >>>> >>>> >>> >>> >>> -- >>> http://g3xbm-qrp.blogspot.com/ >>> http://www.g3xbm.co.uk >>> http://www.youtube.com/user/g3xbm >>> G3XBM GQRP 1678 ISWL G11088 >>> >>> >>> >>> NEU: WEB.DE DSL f=FCr 19,99 EUR/mtl. und ohne Mindest-Laufzeit! >>> http://produkte.web.de/go/02/ >>> >> >> >> >> -- >> http://g3xbm-qrp.blogspot.com/ >> http://www.g3xbm.co.uk >> http://www.youtube.com/user/g3xbm >> G3XBM GQRP 1678 ISWL G11088 >> > > > > -- > http://g3xbm-qrp.blogspot.com/ > http://www.g3xbm.co.uk > http://www.youtube.com/user/g3xbm > G3XBM GQRP 1678 ISWL G11088 > --=20 http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/g3xbm G3XBM GQRP 1678 ISWL G11088 --0015174bf27497521b04875d3c12 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Yes Rik, my current earth-mode tests are around 1kHz so the signal is audi= ble in my crystal earpiece. My TX consists of a TDA2003 fed by a 1kHz osci= llator keyed every second, so I hear a distinctive "beep,=A0=A0 beep,= =A0=A0=A0 beep..." at the RX end.

I measured the DC resistance between the (original) TX electrodes as= around 40-60 ohms and I use a toroidal step-up transformer to achieve rou= gh matching. At the RX end the loop is untuned. When using an up-converter= or direct conversion receiver (such as M0BMUs) I will try at 8.97kHz as= well. I still have a LOT to do to optimise the receive system before I tr= y QRSS or WSPR to extend range.

It's all basic, low tech, stuff but it is such fun, HI.

73s=
Roger G3XBM

On 24 May 2010 21:37, Ri= k Strobbe <Rik.Strobbe@fys.kuleuven.be> wrote:
Hello Roger,
=A0
interesting.
Did I read it correct that your tran= smit frequency is 1kHz instead of 9kHz ?
I gues that also ground antennas bec= ome more efficient at higher frequencies.
How did you match the antenna ?
=A0
73, Rik=A0 ON7YD - OR7T
=A0
Van: owner-rsgb_lf= _group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens Ro= ger Lapthorn [rogerlapthorn@gmail.com]
Verzonden: maandag 24 mei 2010 22:28
Aan: rsgb_lf_group@blacksheep.org
Onderwerp: Re: LF: AW: 8.97kHz - Near field and radiated signals?
Attached is a map showing how far I managed on 1kHz earth mode this= evening. Green is strong RS56 signals and orange is just copied RS33 sign= als, by ear. TX power 4W + 20m base electrodes, RX 80cm loop.

73s
Roger G3XBM

On 24 May 2010 20:36, Roger Lapthorn <= rogerlapthorn@gmail.com> wrote:
Thanks Horst.=A0

I'll try a Marconi antenna at some point, although my space is limited= to little more than the antenna I used on 500kHz (a top loaded 5m vertica= l).

This evening I extended the TX electrode spacings by connecting one end to= the copper pipes in the house, almost doubling the effective TX baseline= to about 20m. With this, my "earth mode" signals were much stronger and I was able to cover further than before in a &quo= t;by ear" walk-about test around the fields.=A0 Ultimate range tonigh= t was 0.4kms using 4W (probably less as the TDA2003 was hot and probably= turning down the power) and receiving on an 80cm loop. active HPF, small AF amp and crystal earpiece.=A0 Range was limited= by 50Hz mains hum and background sferic noise. I must try this set-up wit= h my HF up-converter and FT817 this week which has good rejection of 50Hz= =A0 (and its harmonics) mains hum and a narrow CW filter.

73s
Roger G3XBM




On 24 May 2010 18:18, Horst St=F6cker <ho= rst.stoecker@web.de> wrote:
Hello Roger, Dreamers,
if we define near field as < 2 lambda we are talking about everything= below 60 km.With this distance I woul be extremely lucky.
I also do "walkaround tests" near my garden. But I bet only in= the flat field one can see what is possible with small antenna an without= a big loading coil.
Out from my garden I tried my 10h/20t Marconi as well as a 30m earth base.= The Marconi worked better, but not good enough. A TV transformer (must be= flyback of course) made it much better.
But all the trees and houses are coupling the radiated signal to earth and= also the AATIS-RX is very much influenced by them.
I also assume that the horinontal parts of a wire do the same. So only a= vertical should work.
For operation in city environment smaller antennas at the roof top (old CB= antennas) will possibly work better than the bigger vertical in my garden= between trees and houses at ground level. It might be worth a test.
One of the next tests will be with my gig earth base. I have collected abo= ut 800m of surplus wire. Possibly this is another way to even radiate more= then near field. But I would be very surprised it this was good for any= DX.
I bet Stefans kite antenna will at least be the only way to DX operation.= Unfortunately this is just portable and just temporary.
vy73 Horst DO1KHS/DI2AN
Von: Roger Lapthorn <rogerlapthorn@gmail.com>
Gesendet: 24.05.2010 18:36:28 Betreff: Re: LF: AW: 8.97kHz - Near field and radiated signals?


Thank you for your fast reply Stefan.

In answer to your questions:
  • Currently, my TX electrode spacing is 10m, which is the best I= can manage in my small garden. Both electrodes are as far away from the= mains and other utility services as I can manage.
  • I have not tried /P transmit testing yet.
  • My n= earest ham who will listen/look is 3kms away, but using beaconing I am= able to go out myself and see how far I can reach. This is what I have do= ne so far, going out into the fields behind my house with electrode pairs= or a loop receiver. Best (by ear reception) DX is 0.35kms, but the system has much scope for optim= isation still.
  • The largest single turn loop I could erect in my garden would be= about 50-70 sq m (about 15m top and 4m-5m high). The longest antenna leng= th would also be 15m horizontal with some vertical section(s) too.
  • The best DX targets are quite modest: I would like to exceed 1km= initially with the TX power I currently have (around 4W). If I could reac= h G6ALB in the next village 3kms away I would be delighted. If I got any= further I would be both amazed and VERY happy!
73s
Roger G3XBM


2010/5/24 Stefan Sch=E4fer <schaefer@hst.tu-da= rmstadt.de>
Hello Roger,

For your ground electrodes, ground electrodes may be the best "antenn= a" in some 10...10m. I'm not sure how to calculate field strength= s but i just know about the 1/d^3 dependency, so twice the distance means= 8 times the power for the same signal reception, in the near field. But it is the question what are the electrodes since= there is ever a coupling to the mains earth and all the metallic stuff in= regions where people are living so this dependency might not be valid in= your tests. As mentioned here, you could benefit from these conductors...

But if you want to reach more distance with an antenna of the same size (e= .g. of your garden)and the same power, you could try such a TV transformer= . Take a wire, as long as possible and as high as possible, and apply some= kV on it by this transformer. It can even be resonated by adjusting the air gap between the both ferrite parts= . That results in a maximum output voltage and thus "ERP". At le= ast this would be a good alternative to your ground electrode tests. You= could easily compare the reachable distances. Here i would use a E field antenna for reception in the near field.

How far is your next receiving amateur radio station away? And have you tr= ied to do such tests outside the village/city, just like Jim does it with= his loop antenna? This could allow you to increase the distance of your= reception. Here, space is not limited and you could try 2x10m, 2x50m, 2x100m and so on and tell us the differen= ce in the feed point impedance at various frequencies and your ODX :-) May= be i will also do some ground electrode tests in summer but i am still not= sure. The complete receiver of Jim is a really good idea to check the QRM situation at a given QTH. Probably= i will also buit his loop design for such tests... Would be interesing wh= at is the maximum distance for a CW reception of my transmitted signal (wi= th the kite antenna and 6mW ERP) ;-)

I will also do some near field tests in this week, to compare the performa= nce of my 2 grabbers. This will be done here: http://www.google.de/maps?f=3Dq&source=3Ds_q&hl=3Dde&geocode= =3D&q=3Dheiligenberg+heidelberg&sll=3D47.820666,9.312449&sspn= =3D0.106733,0.219383&g=3Dheiligenberg&ie=3DUTF8&hq=3D&hnea= r=3DHeiligenberg&ll=3D49.419391,8.704101&spn=3D0.001616,0.003428&a= mp;t=3Dh&z=3D18 in about 1,8km distance to my grabbers. Power will also be below 100W and the antenna wire will be= mounted on a tower in abt 15m height. I will transmit with this TV transf= ormer on a 40m wire.

Roger, what size is your garden? What is the maximum wire length that you= can apply and in which height? What is your goal (best DX, a reals QSO wi= th the next equipped station or just do some funny tests?)

So, wish you fun and success with your experiments!

73, Stefan/DK7FC

PS: What is your locator / QTH?




--
http://g3xbm-= qrp.blogspot.com/
http://www.g3xbm.co.u= k
http://www= .youtube.com/user/g3xbm
G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088
=A0=A0

3D""
NE= U: WEB.DE DSL f=FCr 19,99 EUR/mtl. und ohne Mindest-Laufzeit!=A0=A0=A0 http://produkt= e.web.de/go/02/



--
http://g3xbm-= qrp.blogspot.com/
http://www.g3xbm.co.u= k
http://www= .youtube.com/user/g3xbm
G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088



--
http://g3xbm-= qrp.blogspot.com/
http://www.g3xbm.co.u= k
http://www= .youtube.com/user/g3xbm
G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088



--
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/g3xbm
G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088
--0015174bf27497521b04875d3c12--