Return-Path: Received: from rly-dg12.mx.aol.com (rly-dg12.mail.aol.com [172.19.151.96]) by air-dg05.mail.aol.com (v123.4) with ESMTP id MAILINDG053-6114a1ac6da28f; Mon, 25 May 2009 12:27:19 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-dg12.mx.aol.com (v123.4) with ESMTP id MAILRELAYINDG128-6114a1ac6da28f; Mon, 25 May 2009 12:27:09 -0400 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1M8d0S-00051x-46 for rs_out_1@blacksheep.org; Mon, 25 May 2009 17:26:32 +0100 Received: from [83.244.159.144] (helo=relay3.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1M8d0R-00051o-AN for rsgb_lf_group@blacksheep.org; Mon, 25 May 2009 17:26:31 +0100 Received: from ttsmtp-1.cpwnetworks.com ([62.24.128.242] helo=ttsmtp.cpwnetworks.com) by relay3.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1M8d0O-0005jL-IC for rsgb_lf_group@blacksheep.org; Mon, 25 May 2009 17:26:31 +0100 X-Path: TalkTalk-smtp X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: Au0GALJjGkpZ8IyR/2dsb2JhbACCIjCCAodHgUm+fIQLBQ Received: from unknown (HELO mal769a60aa920) ([89.240.140.145]) by ttsmtp.cpwnetworks.com with SMTP; 25 May 2009 17:26:18 +0100 Message-ID: <006401c9dd55$89291760$0301a8c0@mal769a60aa920> From: "mal hamilton" To: References: Date: Mon, 25 May 2009 17:26:19 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: G0MRF QRV Content-Type: multipart/alternative; boundary="----=_NextPart_000_0061_01C9DD5D.EA6CB6A0" 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,LINES_OF_YELLING 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-IP: 193.82.116.20 ------=_NextPart_000_0061_01C9DD5D.EA6CB6A0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable ----- Original Message -----=20 From: G0MRF@aol.com=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Monday, May 25, 2009 4:37 PM Subject: Re: LF: G0MRF QRV Hi all. Firstly, thank you to Jim and Chris for the QSOs yesterday and for the man= y useful reports and comments on the relector.=20 Some detail. THE OBJECTIVE: To test the very good theory that horizontal antennas don= 't work at LF. The idea being that by operating on very poor ground you are=20= actually many 10s of metres above 'radio ground' and therefore the antenna i= s much higher electrically than you may first imagine. This technique is use= d by the US military in underground nuclear command centres to avoid EMP. The location in East Sussex is at the top of a hill 170m above sea level.=20= The ground goes down rapidly in two directions which I hoped would also aid=20= the propagation of the 500k signals. We started off with a reference antenna - A 9m vertical with a 5m top sect= ion and intended to use reports and the grabber at G3YXM to evaluate the rad= iated signal by comparison to the 100mW ERP 137.7 beacon. This was a big mis= take as the poor ground made it very inefficient, with 100 W from the transm= itter generating an unimpressive 125mA of antenna current. However, it did a= llow a couple of QSOs. We then added a large amount of wire to the top section to make the antenn= a self resonant. To my surprise, and I'm not sure if this has been done befo= re, it worked. Total wire used 128 metres. Series tuning inductance....zero.= Compared to the wavelength of 596m this represents 85% of a quarterwave,=20= which was rather more than I had anticipated. I expected the 'shortening eff= ect' to be much greater. Perhaps this was a good indication that as I suspec= ted the 'ground' under the antenna was either a considerable distance from t= he surface or, operating from a hilltop had an advantage. Antenna current wa= s now 1A. Still not very good but this was due to us using the quaterwave ag= ainst a few radials and a single ground rod. I notice that Rik reports a si= gnal increase between the two different antenna types, but this could be exp= lained by higher current in the vertical rather than any radiation from the=20= horizontal section. Just when things were looking good, it all went, to use a local term, 'pea= r shaped' It began to get dark. The static level wiped out the grabber so we could=20= not see our own signal and our final plan to turn the whole thing into a sin= gle horizontal dipole mounted along the ridge of a hilltop had to be abandon= ed as one of the 2 fields suddenly acquired a large flock of sheep. So, unfortunately a nice day in the countryside but only a little knowledg= e gained and the transmitter never turned up beyond 100W. Next time...I'll take a VNA and start with a dipole! At least the local m= anager at Homebase wont have to worry where all his 2 m bamboo canes are goi= ng anymore. My garage is full of them! Finally, to answer Dave's question about the callsign. I have probably mi= sread my NOV but I was under the impression that just like the old 73k licen= ce, /P was not allowed. Hence a letter to OFCOM a week in advance changed m= y 'station address' to East Sussex for the weekend. - So although I was work= ing from a field....they knew where to find me. As for 10 W ERP. - We probably made about 2% of that. Sorry Mal. Oh wel= l. To be continued..? ENOUGH ENOUGH - NO MORE PSE !!!!!!=20 G3KEV David G0MRF In a message dated 25/05/2009 08:34:52 GMT Standard Time, dave@davesergean= t.com writes: On 24 May 2009 at 18:24, James Moritz wrote: > Dear LF Group, >=20 > Just worked G0MRF at 1705utc. Signal was 549 - apparently they are sti= ll > working on the antenna, so might improve yet... Got a good report from > them, so obviously receiving OK. Good luck for the rest of the > operation, David and Garo. >=20 > Cheers, Jim Moritz > 73 de M0BMU=20 >=20 >=20 I listened on and off to David's signal yesterday evening between other=20 jobs. Some observations.... G0MRF (/P but not sending /P, which I thought was a bit confusing) was=20 569 here in Bracknell, later peaking 579 but the static was intolerable=20 from around 9pm making copy very hard. I did give David a couple of calls after he finished his QSO with Chris=20 G3XIZ but obviously he didn't hear, hardly surprising with my setup and=20 in any case I found the tuning had gone off and I had a bad SWR, a=20 problem with sharply tuned short verticals. ----------------------------------------------------------------------------= -- No virus found in this incoming message. Checked by AVG - www.avg.com=20 Version: 8.5.339 / Virus Database: 270.12.37/2131 - Release Date: 05/24/09= 07:09:00 ------=_NextPart_000_0061_01C9DD5D.EA6CB6A0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
 
----- Original Message -----
G0MRF@aol.com <= /DIV>
Sent: Monday, May 25, 2009 4:37 PM<= /DIV>
Subject: Re: LF: G0MRF QRV

Hi all.
 
Firstly, thank you to Jim and Chris for the QSOs yesterday and f= or=20 the many useful reports and comments on the relector.
 
Some detail.
 
THE OBJECTIVE:  To  test the very good theory that horizont= al=20 antennas don't work at LF. The idea being that by operating on very poor=20 ground you are actually many 10s of metres above 'radio ground' and theref= ore=20 the antenna is much higher electrically than you may first imagine. This=20 technique is used by the US military in underground nuclear command=20 centres to avoid EMP.
 
The location in East Sussex is at the top of a hill 170m above sea le= vel.=20 The ground goes down rapidly in two directions which I hoped would also ai= d=20 the propagation of the 500k signals.
 
We started off with a reference antenna - A 9m vertical with a 5m top= =20 section and intended to use reports and the grabber at G3YXM to evaluate t= he=20 radiated signal by comparison to the 100mW ERP 137.7 beacon. This was a bi= g=20 mistake as the poor ground made it very inefficient, with 100 W from the=20 transmitter generating an unimpressive 125mA of antenna current. However,=20= it=20 did allow a couple of QSOs.
 
We then added a large amount of wire to the top section to make=20= the=20 antenna self resonant. To my surprise, and I'm not sure if this has been d= one=20 before, it worked. Total wire used 128 metres. Series tuning=20 inductance....zero.   Compared to the wavelength of 596m this=20 represents 85% of a quarterwave, which was rather more than I had anticipa= ted.=20 I expected the 'shortening effect' to be much greater. Perhaps this was a=20= good=20 indication that as I suspected the 'ground' under the antenna was either a= =20 considerable distance from the surface or, operating from a hilltop had an= =20 advantage. Antenna current was now 1A. Still not very good but this was du= e to=20 us using the quaterwave against a few radials and a single ground rod.&nbs= p; I=20 notice that Rik reports a signal increase between the two different antenn= a=20 types, but this could be explained by higher current in the vertical rathe= r=20 than any radiation from the horizontal section.
 
Just when things were looking good, it all went, to use a local term,= =20 'pear shaped'
It began to get dark.  The static level wiped out the grabber so= we=20 could not see our own signal and our final plan to turn the whole thing in= to a=20 single horizontal dipole mounted along the ridge of a hilltop had to be=20 abandoned as one of the 2 fields suddenly acquired a large flock of=20 sheep.
 
So, unfortunately a nice day in the countryside but only a=20 little knowledge gained and the transmitter never turned up beyond=20 100W.
 
Next time...I'll take a VNA and start with a dipole!  At least t= he=20 local manager at Homebase wont have to worry where all his 2 m bamboo cane= s=20 are going anymore. My garage is full of them!
 
Finally, to answer Dave's question about the callsign. I  have=20 probably misread my NOV but I was under the impression that just like the=20= old=20 73k licence, /P was not allowed.  Hence a letter to OFCOM a week= in=20 advance changed my 'station address' to East Sussex for the weekend. - So=20 although I was working from a field....they knew where to find me.
 
As for 10 W ERP.  - We probably made about 2% of that.  Sor= ry=20 Mal.  Oh well.
 
To be continued..?
 
ENOUGH ENOUGH - NO MORE PSE !!!!!! 
 
G3KEV
 
 
 
 
David  G0MRF
 
 
 
 
In a message dated 25/05/2009 08:34:52 GMT Standard Time,=20 dave@davesergeant.com writes:
On 24=20 May 2009 at 18:24, James Moritz wrote:

> Dear LF Group,
>= ;=20
> Just worked G0MRF at 1705utc. Signal was 549 - apparently they=20= are=20 still
> working on the antenna, so might improve yet... Got a good= =20 report from
> them, so obviously receiving OK. Good luck for the r= est=20 of the
> operation, David and Garo.
>
> Cheers, Jim=20 Moritz
> 73 de M0BMU
>
>

I listened on and o= ff=20 to David's signal yesterday evening between other
jobs.

Some=20 observations....

G0MRF (/P but not sending /P, which I thought wa= s a=20 bit confusing) was
569 here in Bracknell, later peaking 579 but the=20 static was intolerable
from around 9pm making copy very hard.
I=20 did give David a couple of calls after he finished his QSO with Chris=20
G3XIZ but obviously he didn't hear, hardly surprising with my setup=20= and=20
in any case I found the tuning had gone off and I had a bad SWR, a=20
problem with sharply tuned short verticals.
<= /DIV>
 


No virus found in this incoming message.
Checked by AVG -=20 www.avg.com
Version: 8.5.339 / Virus Database: 270.12.37/2131 - Releas= e=20 Date: 05/24/09 07:09:00
------=_NextPart_000_0061_01C9DD5D.EA6CB6A0--