Return-Path: Received: from mtain-da07.r1000.mx.aol.com (mtain-da07.r1000.mx.aol.com [172.29.64.79]) by air-df07.mail.aol.com (v127_r1.1) with ESMTP id MAILINDF071-5efa4b9930a7240; Thu, 11 Mar 2010 13:04:23 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-da07.r1000.mx.aol.com (Internet Inbound) with ESMTP id C7B31380000FB; Thu, 11 Mar 2010 13:04:20 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Npmj5-0000FV-LY for rs_out_1@blacksheep.org; Thu, 11 Mar 2010 18:03:15 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Npmj5-0000FM-5L for rsgb_lf_group@blacksheep.org; Thu, 11 Mar 2010 18:03:15 +0000 Received: from mail-bw0-f215.google.com ([209.85.218.215]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Npmj2-0005fT-LY for rsgb_lf_group@blacksheep.org; Thu, 11 Mar 2010 18:03:15 +0000 Received: by bwz7 with SMTP id 7so299071bwz.4 for ; Thu, 11 Mar 2010 10:03:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:content-type; bh=/5GWWKyzaX/5quLADj8///u4dtj+1X2o3wdqaiVVqWs=; b=MoDtgExsF58GTttv1piLvlt9s5NMIAfxk3SO7R4FPOjU2RgmybTY3w5Tw3FZIbyRaJ xosk+aIKgo2qwFpj53m6BSWxNO/SdHRsqTiKEYfnpcnC8GOPrjPK2kjNJ32/sWUjFV4e +gdnymvIPQPCl9nCqOyXQrXcLn4DQNUXp68nw= 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=VNX7uy9AOPSwJevZXOZHfnQfT65gqf1YirwB4k6LDqhg/CXqQS0btkINH8eMmn/dH/ IofHLd7Ntr0sJ6iMgdvkQ0fnfsGYwDaXESv3NkYJV21uWzQRvAXl71J0gBWjEVCrkyAV TfyAgb78AxkNGb7FPQHOrRhQpa/LWyju8lNhI= MIME-Version: 1.0 Received: by 10.204.128.82 with SMTP id j18mr2091583bks.133.1268330586547; Thu, 11 Mar 2010 10:03:06 -0800 (PST) In-Reply-To: <000a01cac139$b9d5e5a0$0401a8c0@xphd97xgq27nyf> References: <000a01cac139$b9d5e5a0$0401a8c0@xphd97xgq27nyf> Date: Thu, 11 Mar 2010 18:03:06 +0000 Message-ID: <9afca2641003111003j73c81acdl454ca28e6dc9909b@mail.gmail.com> 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: DREAM 9 ANTENNA Content-Type: multipart/alternative; boundary=0015174a0ef211a77504818a3a73 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_20_30,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-d253.2 ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1d404f4b9930a41e45 X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --0015174a0ef211a77504818a3a73 Content-Type: text/plain; charset=ISO-8859-1 Thanks for the good advice Mal. I do hope you can find some time to give 9kHz a go as you'd be such a valuable contributor to any experiments. As a more general question, at what S/N should one expect to receive the ~11kHz Alpha beacon on a well optimised RX? 73s Roger G3XBM On 11 March 2010 16:41, mal hamilton wrote: > Probably an inv L or T antenna as high as possible for TX is the best > solution for 9 kcs. Base load the antenna with the necessary inductance for > resonance and if necessary add another small inductor in series to ground > and adjust with taps up from ground to get a 1 : 1 match with the coax feed > from the TX, readjust the main inductor to maintain resonance if necessary. > This system has never failed me on 73, 137 and 500 kcs and this would be my > approach on 9 kcs. > RX is a different matter and there are a variety of antennas suitable. > I can RX the Alpha signals around 12 kcs at good strength using my 500 kcs > 1/4 wave inv L and weaker on the 40m loop both antennas not resonated for 9 > kcs. > Obviously if resonated the signals would be very strong with these > antennas. > 9 kcs is a lot easier to get going than the other LF/MF bands because there > is an abundance of LF generators and high power audio amplifiers about, > I would suggest modifying a audio amp output to 50 ohms with a suitable > transformer then use existing station equipment for monitoring and > measuring. > Suggested approach for making a large inductor to resonate antenna. > Get several slotted laundry baskets size diam 600mm, height about the same, > stiff plastic material. Wind some wire on a few and connect in series with > antenna and check for resonance, then add baskets as necessary to resonate > at desired frequency These baskets fit into one another and look tidy. > Use the largest diam wire possible to achieve the desired inductance. If > using a vy small inv L with lots of Henries required then go for the water > butt coil former. > Do not forget some earth radials and rods. > I could probably manage about 4 inv L antennas in parallel, 500 kcs size, > loaded against ground and would hope the signal would travel some hundreds > of miles. > If only I had the time. > de mal/g3kev > > > > > > -- http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/G3XBM G3XBM GQRP 1678 ISWL G11088 --0015174a0ef211a77504818a3a73 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Thanks for the good advice Mal.=A0 I do hope you can find some time to giv= e 9kHz a go as you'd be such a valuable contributor to any experiments= .

As a more general question, at what S/N should one expect to rec= eive the ~11kHz Alpha beacon on a well optimised RX?

73s
Roger G3XBM


On 11 March= 2010 16:41, mal hamilton <g3kevmal@talktalk.net> wrote:
Probably an inv L or T antenna as hig= h as possible=20 for TX =A0is the best solution for 9 kcs. Base load the antenna with the= =20 necessary inductance for resonance=A0and if necessary add another small=20 inductor=A0in series to ground and adjust with taps up from ground to get= a 1=20 : 1 match with the coax feed from the TX,=A0 readjust the main inductor to= =20 maintain resonance if necessary.
This system has never failed me on 73= , 137 and 500=20 kcs and this would be my approach on 9 kcs.
RX is a different matter and there ar= e a variety of=20 antennas suitable.
I can RX the Alpha signals around 12= kcs at good=20 strength using my 500 kcs 1/4 wave inv L and weaker on the 40m loop both= =20 antennas not resonated for 9 kcs.
Obviously if resonated the signals wo= uld be very=20 strong with these antennas.
9 kcs is a lot easier to get going th= an the other=20 LF/MF bands because there is an abundance of LF=A0generators and high=20 power=A0audio amplifiers about,
I would suggest modifying a audio amp= output to 50=20 ohms with a suitable transformer then use existing station equipment for= =20 monitoring and measuring.
Suggested approach for making a large= inductor to=20 resonate antenna.
Get several slotted laundry baskets= size diam=20 600mm, height about the same, stiff plastic material. Wind some wire on a= few=20 and connect in series with antenna and check for resonance, then add baske= ts as=20 necessary to resonate at desired frequency These baskets fit into one anot= her=20 and look tidy.
Use the largest diam wire=A0possible= to achieve=20 the desired inductance. If using a vy small inv L with lots of Henries req= uired=20 then=A0go for the water butt coil former.
Do not forget some earth radials and= =20 rods.
I could probably manage about 4 inv= L antennas in=20 parallel, 500 kcs size, loaded against ground and would hope=A0the signal= =20 would travel some hundreds of miles.
If only I had the time.
de mal/g3kev
=A0
=A0
=A0
=A0
=A0



--

http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/G3XBM
G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088
--0015174a0ef211a77504818a3a73--