Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dg02.r1000.mx.aol.com (Internet Inbound) with ESMTP id 966EF380000E0; Fri, 19 Aug 2011 04:47:12 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1QuKiS-00076a-RT for rs_out_1@blacksheep.org; Fri, 19 Aug 2011 09:46:12 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1QuKiS-00076R-8J for rsgb_lf_group@blacksheep.org; Fri, 19 Aug 2011 09:46:12 +0100 Received: from relay.uni-heidelberg.de ([129.206.100.212]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1QuKiR-0006Zk-6K for rsgb_lf_group@blacksheep.org; Fri, 19 Aug 2011 09:46:12 +0100 Received: from freitag.iup.uni-heidelberg.de (freitag.iup.uni-heidelberg.de [129.206.29.204]) by relay.uni-heidelberg.de (8.14.1/8.14.1) with ESMTP id p7J8kA7I023265 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Fri, 19 Aug 2011 10:46:10 +0200 Received: from [129.206.22.206] (pc206.iup.uni-heidelberg.de [129.206.22.206]) by freitag.iup.uni-heidelberg.de (8.12.11.20060308/8.11.2) with ESMTP id p7J8k96u010959 for ; Fri, 19 Aug 2011 10:46:09 +0200 Message-ID: <4E4E220A.7070706@iup.uni-heidelberg.de> Date: Fri, 19 Aug 2011 10:42:50 +0200 From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <7.0.1.0.1.20110819095835.01ba53e8@xtra.co.nz> <4E4D96F0.6050409@iup.uni-heidelberg.de> <1313740427.69106.YahooMailNeo@web111905.mail.gq1.yahoo.com> <1313740947.33597.YahooMailNeo@web111915.mail.gq1.yahoo.com> In-Reply-To: <1313740947.33597.YahooMailNeo@web111915.mail.gq1.yahoo.com> X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,RATWARE_GECKO_BUILD=1.426 Subject: Re: LF: Ferrite Receive Antennas Content-Type: multipart/alternative; boundary="------------000006020807070808020407" 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-SCORE: 0:2:482741056:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d410a4e4e230f1230 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. --------------000006020807070808020407 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by relay.uni-heidelberg.de id p7J8kA7I023265 Hello Piotr, Daniele, LF, @Daniele: It's fine, i searched for the loopstick article as well,=20 thanks for the link! @Piotr: Hello, nice to see you again here! And happy to see i caused some new activity in homebrewing ;-) DCF39 is about 500 km distant to you. You should receive it some 10 dB=20 better as you did. This is probably caused by local QRM. What is the gain of your amp stage? And what is the Q of the antenna's LC circuit? BTW this small antenna is good to find a quiet place in the local region=20 and help to find the location of local QRM sources. So once one has=20 found the quietest place in the garden, a bigger loop may be instelled=20 there... I have some problems with the dynamic range of my soundcard which is 120=20 dB in 1 Hz. Not bad but DCF39 comes in at up to 97 dB and if i want to=20 stay 15 dB above the soundcards noise (in the passband) it becomes critic= al. I saw that there are big differences between different capacitor types.=20 Replacing a standard foil cap by a styroflex cap increased the Q from=20 130 to 480! I took a cheap variable cap (100 pF) with a foil=20 dielectricum to resonate the antenna and saw that Q decreases with=20 increasing C of this small cap. The styroflex type is 2.2 nF. Then i=20 found a 47 pF silver plated varable cap with air dielectricum which even=20 has a 6mm axis. Now i think about using this cap and some switches and=20 fixed caps (47 pF, 100 pF, 220 pF) for resonating... About the winding on my antenna: I stopped optimising after getting that=20 Q of 486 at 55 turns but actually it could be useful to further increase=20 the number of turns as long as the Q doesn't decrease to much. Have to=20 do some tests with various C values and see how the Q changes as a=20 function of frequency. More turns would result in a higher output=20 voltage. Furthermore i would get a wider range of frequency variation by=20 that small 47 pF varicap. The current Z of my LC circuit is just about=20 500 Ohm... Will you further optimise your system and try to receive some DX signals=20 with it or was it just a test? :-) 73, Stefan/DK7FC Am 19.08.2011 10:02, schrieb Daniele Tincani: > Sorry, now I understand that a PDF of the ARRL article was looked for. > My apologies for having sent not the desired link. > Regards > Daniele > > *From:* Daniele Tincani > *To:* "rsgb_lf_group@blacksheep.org" > *Sent:* Friday, August 19, 2011 9:53 AM > *Subject:* Re: LF: Ferrite Receive Antennas > > Hi Stefan, LF, > here it is: > http://om6bb.bab.sk/files/HAM%20kniznica/Magaziny/QEX/02%20March-April%= 202000%20QEX.pdf > Regards > Daniele > > *From:* Stefan Sch=E4fer > *To:* rsgb_lf_group@blacksheep.org > *Sent:* Friday, August 19, 2011 12:49 AM > *Subject:* Re: LF: Ferrite Receive Antennas > > Can we get a link to a pdf about this article? > > 73, Stefan/DK7FC > > Am 19.08.2011 00:06, schrieb Brenda Hayes: > > At 02:27 a.m. 19/08/2011, you wrote: > >> Hello LFers, > >> > >> Take a look at the article on page 45 of the ARRL Antenna=20 > Compendium Volume 6 about a > >> very interesting receive antenna for 160 and 80 meters. LF usage=20 > should be possible with > >> some component value changes. > >> > >> 73, J.B., VE3EAR > >> > >> LowFER Beacon "EAR" > >> 188.830 kHz. QRSS30 > >> EN93dr > > > > Also see QEX March/April 2000, page 20 - "A Giant LF Loopstick" by=20 > Richard Q.Marris, G2BZQ. > > > > 73, Kevin, ZL4MD > > > > > > > > > > > --------------000006020807070808020407 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Hello Piotr, Daniele, LF,

@Daniele:  It's fine, i searched for the loopstick article as well, thanks for the link!

@Piotr: Hello, nice to see you again here!
And happy to see i caused some new activity in homebrewing ;-)
DCF39 is about 500 km distant to you. You should receive it some 10 dB better as you did. This is probably caused by local QRM.
What is the gain of your amp stage?
And what is the Q of the antenna's LC circuit?
BTW this small antenna is good to find a quiet place in the local region and help to find the location of local QRM sources. So once one has found the quietest place in the garden, a bigger loop may be instelled there...
I have some problems with the dynamic range of my soundcard which is 120 dB in 1 Hz. Not bad but DCF39 comes in at up to 97 dB and if i want to stay 15 dB above the soundcards noise (in the passband) it becomes critical.

I saw that there are big differences between different capacitor types. Replacing a standard foil cap by a styroflex cap increased the Q from 130 to 480! I took a cheap variable cap (100 pF) with a foil dielectricum to resonate the antenna and saw that Q decreases with increasing C of this small cap. The styroflex type is 2.2 nF. Then i found a 47 pF silver plated varable cap with air dielectricum which even has a 6mm axis. Now i think about using this cap and some switches and fixed caps (47 pF, 100 pF, 220 pF) for resonating...

About the winding on my antenna: I stopped optimising after getting that Q of 486 at 55 turns but actually it could be useful to further increase the number of turns as long as the Q doesn't decrease to much. Have to do some tests with various C values and see how the Q changes as a function of frequency. More turns would result in a higher output voltage. Furthermore i would get a wider range of frequency variation by that small 47 pF varicap. The current Z of my LC circuit is just about 500 Ohm...

Will you further optimise your system and try to receive some DX signals with it or was it just a test? :-)

73, Stefan/DK7FC


Am 19.08.2011 10:02, schrieb Daniele Tincani:
Sorry,  now I understand that a PDF of the ARRL article was looked for.
My apologies for having sent not the desired link.
Regards
Daniele

From: Daniele Tincani <danieletincani@yahoo.com>
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
Sent: Friday, August 19, 2011 9:53 AM
Subject: Re: LF: Ferrite Receive Antennas

Hi Stefan, LF,
 
here it is:
 
 
Regards
Daniele

From: Stefan Schäfer <Stefan.Schaefer@iup.uni-heidelberg.de>
To: rsgb_lf_group@blacksheep.org
Sent: Friday, August 19, 2011 12:49 AM
Subject: Re: LF: Ferrite Receive Antennas

Can we get a link to a pdf about this article?

73, Stefan/DK7FC

Am 19.08.2011 00:06, schrieb Brenda Hayes:
> At 02:27 a.m. 19/08/2011, you wrote:
>> Hello LFers,
>>
>> Take a look at the article on page 45 of the ARRL Antenna Compendium Volume 6 about a
>> very interesting receive antenna for 160 and 80 meters.  LF usage should be possible with
>> some component value changes.
>>
>> 73, J.B., VE3EAR
>>
>> LowFER Beacon "EAR"
>> 188.830 kHz. QRSS30
>> EN93dr
>
> Also see QEX  March/April 2000, page 20 - "A Giant LF Loopstick" by Richard Q.Marris, G2BZQ.
>
> 73,      Kevin,    ZL4MD
>
>
>





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