Return-Path: Received: from mtain-me05.r1000.mx.aol.com (mtain-me05.r1000.mx.aol.com [172.29.96.141]) by air-df07.mail.aol.com (v129.4) with ESMTP id MAILINDF071-5efa4bfaf7a327a; Mon, 24 May 2010 18:03:15 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-me05.r1000.mx.aol.com (Internet Inbound) with ESMTP id 1A24B3800004E; Mon, 24 May 2010 18:03:13 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OGfir-0003n0-Go for rs_out_1@blacksheep.org; Mon, 24 May 2010 23:02:09 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OGfiq-0003mr-Ke for rsgb_lf_group@blacksheep.org; Mon, 24 May 2010 23:02:08 +0100 Received: from mail-fx0-f43.google.com ([209.85.161.43]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1OGfio-0001p4-1x for rsgb_lf_group@blacksheep.org; Mon, 24 May 2010 23:02:08 +0100 Received: by fxm13 with SMTP id 13so2319045fxm.16 for ; Mon, 24 May 2010 15:02:00 -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=cH1n0W8EOOYM6rzB7mxxLL4VsvTzY/LZtAiTj/eJdR4=; b=TodGkWoczaPbN5a7Yk4npAP1OqnYYxlH8f+7wgG2QgNxtKpItv8zfuCWvKP7tHmuPQ CZRqyeMwezsd7fISpfR5ZJdV1HXTr4G54DXh05NjZ1kXvxgn6jkoen8cNFGQLERTQouN aSxJLZtTCtn8YYBiowxIS0RMvef5A2KnpsecM= 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=EKldRie6Pf8/7tvUpr3g8qurs0G3LMf7nKDpNqKsY9o2rxcheqstSEZe/evqXHsxFa wLbmr3O7jdKzaH/XPP7Qs8O3f34oeNcHN9zdelfFDEsr19nTpC7HXIHYXGR6jUMuB3UB 6+/+OKa8LPx3mcC/oUiqYriBDD+Kew9dF1VBQ= MIME-Version: 1.0 Received: by 10.204.4.194 with SMTP id 2mr2477211bks.53.1274738519245; Mon, 24 May 2010 15:01:59 -0700 (PDT) Received: by 10.204.58.204 with HTTP; Mon, 24 May 2010 15:01:59 -0700 (PDT) In-Reply-To: <38A51B74B884D74083D7950AD0DD85E82A1C03@File-Server-HST.hst.e-technik.tu-darmstadt.de> References: <38A51B74B884D74083D7950AD0DD85E82A1C00@File-Server-HST.hst.e-technik.tu-darmstadt.de> <38A51B74B884D74083D7950AD0DD85E82A1C03@File-Server-HST.hst.e-technik.tu-darmstadt.de> Date: Mon, 24 May 2010 23:01:59 +0100 Message-ID: From: Roger Lapthorn 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: AW: 8.97kHz - Near field and radiated signals? Content-Type: multipart/alternative; boundary=0015174bf2749f0a3304875e30ee 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-m225.2 ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1d608d4bfaf7a11806 X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --0015174bf2749f0a3304875e30ee Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Stefan, On windy days the large field behind my house does have people flying kite= s in it. Yes, my young grandchildren would love this! At the moment I want to avoid using a PC on RX as it only takes a few minutes to leave the house, do the "by ear" walk tests, and return home. When I am reasonably sure the RX is working pretty well then I shall certainly try QRSS or WSPR using a PC to see just what range can be achieved. Double the audible range would be my expectation based on 18dB additional path loss for doubling distance and this sort of RX improvement factor using QRSS. The idea of putting a 100m earth electrode baseline TX in the field is a good one as increasing the baseline would certainly have a direct impact= on range. This will need a second person helping: people walk dogs in the field, so someone would have to keep an eye on the TX set-up for health an= d safety reasons. Thanks for your encouragement to keep experimenting. 73s Roger G3XBM 2010/5/24 Stefan Sch=E4fer > OK Roger, very nice! > > If you would go to use a PC instead your ears, you could immediately get > some "gain" of say 30 dB and thus much more distance. I also like and > normally prefer CW instead of ear reception. Normally i say " a PC has= not > to be a part of a amateur radio station", very conservative, hi. Even my > logbock is hand drawn since i do not like having a PC running during the > QSOs. But on (LF)/VLF it is the best way to communicate. On 137 kHz it= is > rather due to the activity that is more in QRSS than in CW but... > So, if you would try SpecLab or Argo on a PC and use a stable VFO i thin= k > it is no problem to reach those 3kms in say DFCW-600. Than, it is much= more > easy to improve your system since you can see how a change of your setup > improves the reception. If you can improve some dB, maybe even 10 dB, yo= u > could go to DFCW-60 and so on. And you can really try a TV transformer!= That > would really make sense in some kms at small antennas. > > Now, as i saw your QTH i get the idea to ask you if you don't want to bu= y a > kite ;-) It's just funny to have it in the air, even without antennas > mounted on it. Also your grad children would enjoy it ;-) And you would= be > one of the top 3 of your VLF dx list ;-) > > I think i will ask Bernd/DF8ZR if he is interested to do some ground > electrode tests with me. He is in 16km distance and if we would try > DFCW-600, maybe it is possible. Also it would be interesting to see the > QRN/QRM daily time dependency... All this is interesting stuff. > Go on with your tests and report us :-) > > Best wishes :-) > > Stefan/DK7FC > > ________________________________ > > Von: owner-rsgb_lf_group@blacksheep.org im Auftrag von Roger Lapthorn > Gesendet: Mo 24.05.2010 18:36 > 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 main= s > 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 0.35km= s, > 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 antenna len= gth > 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 rea= ch > 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 > "antenna" 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 livin= g 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 sam= e > 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 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 ha= ve > 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= your > reception. Here, space is not limited and you could try 2x10m, 2x50m, 2x= 100m > and so on and tell us the difference in the feed point impedance at vari= ous > frequencies and your ODX :-) Maybe 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 what is= the > maximum distance for a CW reception of my transmitted signal (with the= 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=3Dheil= igenberg+heidelberg&sll=3D47.820666,9.312449&sspn=3D0.106733,0.219383&g=3D= heiligenberg&ie=3DUTF8&hq=3D&hnear=3DHeiligenberg&ll=3D49.419391,8.704101&= spn=3D0.001616,0.003428&t=3Dh&z=3D18in 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 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 re= als > 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 > > --=20 http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/g3xbm G3XBM GQRP 1678 ISWL G11088 --0015174bf2749f0a3304875e30ee Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Stefan,

On windy days the large field behind my house does have peo= ple flying kites in it. Yes, my young grandchildren would love this!
<= br>At the moment I want to avoid using a PC on RX as it only takes a few= minutes to leave the house, do the "by ear" walk tests, and ret= urn home. When I am reasonably sure the RX is working pretty well then I= shall certainly try QRSS or WSPR using a PC to see just what range can be= achieved. Double the audible range would be my expectation based on 18dB= additional path loss for doubling distance and this sort of RX improvemen= t factor using QRSS.

The idea of putting a 100m earth electrode baseline TX in the field is= a good one as increasing the baseline would certainly have a direct impac= t on range. This will need a second person helping: people walk dogs in th= e field, so someone would have to keep an eye on the TX set-up for health= and safety reasons.

Thanks for your encouragement to keep experimenting.

73s
Rog= er G3XBM

2010/5/24 Stefan Sch=E4fer <schaefer= @hst.tu-darmstadt.de>
OK Roger, very= nice!

If you would go to use a PC instead your ears, you could immediately get= some "gain" of say 30 dB and thus much more distance. I also li= ke and normally prefer CW instead of ear reception. Normally i say "= a PC has not to be a part of a amateur radio station", very conserva= tive, hi. Even my logbock is hand drawn since i do not like having a PC ru= nning during the QSOs. But on (LF)/VLF it is the best way to communicate.= On 137 kHz it is rather due to the activity that is more in QRSS than in= CW but...
So, if you would try SpecLab or Argo on a PC and use a stable VFO i think= it is no problem to reach those 3kms in say DFCW-600. Than, it is much mo= re easy to improve your system since you can see how a change of your setu= p improves the reception. If you can improve some dB, maybe even 10 dB, yo= u could go to DFCW-60 and so on. And you can really try a TV transformer!= That would really make sense in some kms at small antennas.

Now, as i saw your QTH i get the idea to ask you if you don't want to= buy a kite ;-) It's just funny to have it in the air, even without an= tennas mounted on it. Also your grad children would enjoy it ;-) And you= would be one of the top 3 of your VLF dx list ;-)

I think i will ask Bernd/DF8ZR if he is interested to do some ground elect= rode tests with me. He is in 16km distance and if we would try DFCW-600,= maybe it is possible. Also it would be interesting to see the QRN/QRM dai= ly time dependency... All this is interesting stuff.
Go on with your tests and report us :-)

Best wishes :-)

Stefan/DK7FC

________________________________

Von: owner-rsgb_lf_g= roup@blacksheep.org im Auftrag von Roger Lapthorn
Gesendet: Mo 24.05.2010 18:36
An: rsgb= _lf_group@blacksheep.org
Betreff: Re: LF: AW: 8.97kHz - Near field and radiated signals?


Thank you for your fast reply Stef= an.

In answer to your questions:


* =A0 =A0 =A0 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.
* =A0 =A0 =A0 I have not tried /P transmit testing yet.

* =A0 =A0 =A0 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.
* =A0 =A0 =A0 The largest single turn loop I could erect in my garden woul= d be about 50-70 sq m (about 15m top and 4m-5m high). The longest antenna= length would also be 15m horizontal with some vertical section(s) too. * =A0 =A0 =A0 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= 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 <schaefer@hst.tu-darmstadt.de>


=A0 =A0 =A0 =A0Hello Roger,

=A0 =A0 =A0 =A0For your ground electrodes, ground electrodes may be the= best "antenna" in some 10...10m. I'm not sure how to calcul= ate 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 th= e 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 regio= ns where people are living so this dependency might not be valid in your= tests. As mentioned here, you could benefit from these conductors...

=A0 =A0 =A0 =A0But 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 possibl= e, 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 compa= re the reachable distances. Here i would use a E field antenna for recepti= on in the near field.

=A0 =A0 =A0 =A0How 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 your reception. Here, space is not limited and you could try= 2x10m, 2x50m, 2x100m and so on and tell us the difference in the feed poi= nt impedance at various frequencies and your ODX :-) Maybe i will also do= some ground electrode tests in summer but i am still not sure. The comple= te 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... Wo= uld be interesing what is the maximum distance for a CW reception of my tr= ansmitted signal (with the kite antenna and 6mW ERP) ;-)

=A0 =A0 =A0 =A0I will also do some near field tests in this week, to comp= are the performance of my 2 grabbers. This will be done here: http://www.google.de/maps?f=3Dq&sou= rce=3Ds_q&hl=3Dde&geocode=3D&q=3Dheiligenberg+heidelberg&s= ll=3D47.820666,9.312449&sspn=3D0.106733,0.219383&g=3Dheiligenberg&= amp;ie=3DUTF8&hq=3D&hnear=3DHeiligenberg&ll=3D49.419391,8.7041= 01&spn=3D0.001616,0.003428&t=3Dh&z=3D18 in about 1,8km dis= tance 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 transformer on a 40m wire.

=A0 =A0 =A0 =A0Roger, 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 with the next equipped station or just do some funny tests?)=

=A0 =A0 =A0 =A0So, wish you fun and success with your experiments!

=A0 =A0 =A0 =A073, Stefan/DK7FC

=A0 =A0 =A0 =A0PS: What is your locator / QTH?






--
http://g3xbm-= qrp.blogspot.com/
http://ww= w.g3xbm.co.uk <http://www.g3xbm.co.uk/>
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
--0015174bf2749f0a3304875e30ee--