Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dh01.r1000.mx.aol.com (Internet Inbound) with ESMTP id 63CE9380001B6; Wed, 17 Aug 2011 12:56:58 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1QtjPA-0000mI-2k for rs_out_1@blacksheep.org; Wed, 17 Aug 2011 17:55:48 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1QtjP9-0000m9-DU for rsgb_lf_group@blacksheep.org; Wed, 17 Aug 2011 17:55:47 +0100 Received: from relay2.uni-heidelberg.de ([129.206.210.211]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1QtjP7-0000yJ-SW for rsgb_lf_group@blacksheep.org; Wed, 17 Aug 2011 17:55:47 +0100 Received: from ix.urz.uni-heidelberg.de (cyrus-portal.urz.uni-heidelberg.de [129.206.100.176]) by relay2.uni-heidelberg.de (8.13.8/8.13.8) with ESMTP id p7HGti5D005809 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Wed, 17 Aug 2011 18:55:45 +0200 Received: from extmail.urz.uni-heidelberg.de (extmail.urz.uni-heidelberg.de [129.206.100.140]) by ix.urz.uni-heidelberg.de (8.13.8/8.13.8) with ESMTP id p7HGtiTV007703 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Wed, 17 Aug 2011 18:55:44 +0200 Received: from [129.206.205.145] (vpn205-145.rzuser.uni-heidelberg.de [129.206.205.145]) by extmail.urz.uni-heidelberg.de (8.13.4/8.13.1) with ESMTP id p7HGtg3B017255 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Wed, 17 Aug 2011 18:55:43 +0200 Message-ID: <4E4BF289.2070500@iup.uni-heidelberg.de> Date: Wed, 17 Aug 2011 18:55:37 +0200 From: =?UTF-8?B?U3RlZmFuIFNjaMOkZmVy?= User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.11) Gecko/20100711 Thunderbird/3.0.6 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <68BE37BD69E54DEE89CEBA8E30E9B94E@PcMinto> <4E47FFE9.10100@iup.uni-heidelberg.de> <3ED8E5422F1F45DBB8186E9D9870AD63@PcMinto> <4E480E02.9020706@iup.uni-heidelberg.de> <938BF599006244949F6CDDB5BA91F347@PcMinto> <4E482FBD.7030402@freenet.de> <4E484183.9090805@iup.uni-heidelberg.de> <4E494A57.90105@freenet.de> <4E4956DA.1060201@iup.uni-heidelberg.de> <4E49643E.5090708@freenet.de> <4E496FF9.4040608@iup.uni-heidelberg.de> <0A4ED65EC3B244A3BD0DAD6ACFF43793@JimPC> <4E4A5597.4070709@iup.uni-heidelberg.de> <3746D901368F4C139E414F9110153EEE@JimPC> <4E4A9A1F.2060600@iup.uni-heidelberg.de> <1B55B625C3CD4D529EC361D9C5D79D96@JimPC> <4E4AD4C8.8000509@iup.uni-heidelberg.de> <4E4AEF31.5010306@iup.uni-heidelberg.de> <1FF2FAD9854F4890A338A9F862D93FE9@JimPC> <8CE2AD319756ED7-1C20-14370@Webmail-m104.sysops.aol.com> <4E4BC177.6050902@iup.uni-heidelberg.de> <001f01cc5cf9$4b734780$0401a8c0@xphd97xgq27nyf> In-Reply-To: <001f01cc5cf9$4b734780$0401a8c0@xphd97xgq27nyf> X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,RATWARE_GECKO_BUILD=1.426 Subject: Re: LF: Ferrite RX antennas Content-Type: multipart/alternative; boundary="------------020701080105080509020706" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.1 required=5.0 tests=HTML_20_30, HTML_FONTCOLOR_UNKNOWN,HTML_MESSAGE,HTML_TITLE_EMPTY 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: 0:2:462458080:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d41154e4bf2da4755 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. --------------020701080105080509020706 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by relay2.uni-heidelberg.de id p7HGti5D005809 Mal, I know. But anyway one can compare the SNR levels between different=20 antennas. I'll set up a beacon now on 137.73 kHz, testing in QRSS-3. Maybe you want to call CQ or so. If i can receive you, i will send a=20 capture. But i still cannot answer. Am in Darmstadt now, not in=20 Heidelberg. The UHF link for transmitting works just in a range of 5 km=20 and is disabled now. I expect that i need a preamp and will not get the necessary sensitivy=20 now. Anyway i can compare the antennas and check how many dBs are missed. RX QRV in half an hour. Beacon starting at 17:30 UTC 73, Stefan/DK7FC Am 17.08.2011 18:18, schrieb mal hamilton: > Stefan > But what sort of strength do you Receive weak Radio Amateur signals.=20 > That is the real test > Commercial radio stations a different matter with their Megawatts > de mal/g3kev > > ----- Original Message ----- > *From:* Stefan Sch=C3=A4fer > *To:* rsgb_lf_group@blacksheep.org > > *Sent:* Wednesday, August 17, 2011 2:26 PM > *Subject:* Re: LF: Ferrite RX antennas > > Hello Markus, Jim, LF, > > Tnx for suggestions. Have to think about that later. I want to go > on in small steps now. > > I added a 100 pF vari-cap which allows to resonate in the desired > range (up to 137.8 kHz and down to 136.3). > As a first test a added a small winding, just 3 turns, 3 cm far > for the rods end, matched to 50 Ohm. So now it works as a passive > antenna and can be fed to my RX 50 Ohm input. > This is the complete LF RX arrangement, suitable to see and hear > on 137 wideband: > http://dl.dropbox.com/u/19882028/LF/LF-P%20RX%20RIG.JPG > > The ferrite antenna is just as broad a the netbook now. Of course > the distance to the netbook must be increased later. It still has > no electric shield but a suitable housing to protect the Litz > winding, necessary to go on with tests on various locations. > > The DCF-39 strength is 50 dB S/N in 1 Hz while the antenna (3 dB > bandwidth =3D 280 Hz) is tuned to 137.0 kHz (cannot tune to 138.83). > The band noise within the passband is 10 dB above the soundcards > noise but this may be different in a quiet location on a quiet day. > > This looks all promising to me. I'll try the BF862 as a preamp soon. > > Will do further tests with a test signal in the passband and > compare this to my 1m diameter single turn loop. And i will try my > 50 Ohm preamp in front of the RX. > Looking forward to the first QSOs! > > 73, Stefan/DK7FC > > Am 17.08.2011 10:59, schrieb Markus Vester: >> Stefan, Jim, >> you could increase the signal bandwidth without compromising SNR >> by connecting a low impedance preamplifier. This technique has >> been used widely and successfully in magnetic resonance imaging >> ("preamp decoupling"). The preamp is designed to have an input >> impedance that differs largely from the noise-optimum source >> impedance, so that you can preserve the noise match but create an >> intentional signal mismatch. >> In practice, you would still want to use a low-noise FET >> connected to the high impedance point of a parallel resonant >> antenna. Normally the gate input impedance (megohms) is higher >> than the noise optimum (tens of kiloohms), so you would have no >> preamp damping at all. The trick is then to lower the input >> impedance by lossless feedback, which has neglegible effect on >> the noise parameters. >> One configuration is a compromise between common source and >> common gate circuit configuration ("Zwischenbasisschaltung"), >> which can be realised by inserting an additional >> negative-feedback winding in the source-to-ground path. This is >> similar to the old regenerative audion, but with the feedback >> coil polarity reversed. Another configuration is parallel >> feedback from drain to gate, by intentionally increasing the >> Miller capacitance. >> >> Best regards, >> Markus (DF6NM) >> -----Urspr=C3=BCngliche Mitteilung----- >> Von: James Moritz >> An: rsgb_lf_group >> Verschickt: Mi, 17 Aug 2011 1:13 am >> Betreff: Re: LF: Ferrite RX antennas >> >> Dear Stefan, >> >> Looking good so far... >> >> A Q of 486 is certainly reaching the point where it becomes inconv= enient - >> but remember that it is easy to reduce Q (probably connecting a pr= eamp, >> putting it in a container, etc, will reduce Q a bit anyway), and t= hat the >> higher Q is, the better the SNR. So I would test it as an antenna = with a >> preamp - if there is more SNR than you need, you could experiment = with some >> damping resistance. >> >> Cheers, Jim Moritz >> 73 de M0BMU >> >> > --------------020701080105080509020706 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by relay2.uni-heidelberg.de id p7HGti5D005809 Mal,

I know. But anyway one can compare the SNR levels between different antennas.

I'll set up a beacon now on 137.73 kHz, testing in QRSS-3.
Maybe you want to call CQ or so. If i can receive you, i will send a capture. But i still cannot answer. Am in Darmstadt now, not in Heidelberg. The UHF link for transmitting works just in a range of 5 km and is disabled now.

I expect that i need a preamp and will not get the necessary sensitivy now. Anyway i can compare the antennas and check how many dBs are missed.

RX QRV in half an hour. Beacon starting at 17:30 UTC

73, Stefan/DK7FC

Am 17.08.2011 18:18, schrieb mal hamilton:
Stefan
But what sort of strength do you Receive weak Radio Amateur signals. That is the real test
Commercial radio stations a different matter with their Megawatts
de mal/g3kev
=C2=A0
----- Original Message -----
From: Stefan Sch=C3=A4fer <= /div>
Sent: Wednesday, August 17, 2011 2:26 PM
Subject: Re: LF: Ferrite RX antennas

Hello Markus, Jim, LF,

Tnx for suggestions. Have to think about that later. I want to go on in small steps now.

I added a 100 pF vari-cap which allows to resonate in the desired range (up to 137.8 kHz and down to 136.3).
As a first test a added a small winding, just 3 turns, 3 cm far for the rods end, matched to 50 Ohm. So now it works as a passive antenna and can be fed to my RX 50 Ohm input.
This is the complete LF RX arrangement, suitable to see and hear on 137 wideband: http://= dl.dropbox.com/u/19882028/LF/LF-P%20RX%20RIG.JPG

The ferrite antenna is just as broad a the netbook now. Of course the distance to the netbook must be increased later. It still has no electric shield but a suitable housing to protect the Litz winding, necessary to go on with tests on various locations.

The DCF-39 strength is 50 dB S/N in 1 Hz while the antenna (3 dB bandwidth =3D 280 Hz) is tuned to 137.0 kHz (cannot tune to 138.83). The band noise within the passband is 10 dB above the soundcards noise but this may be different in a quiet location on a quiet day.

This looks all promising to me. I'll try the BF862 as a preamp soon.

Will do further tests with a test signal in the passband and compare this to my 1m diameter single turn loop. And i will try my 50 Ohm preamp in front of the RX.
Looking forward to the first QSOs!

73, Stefan/DK7FC

Am 17.08.2011 10:59, schrieb Markus Vester:
Stefan, Jim,
=C2=A0
you could increase the signal bandwidth without compromising SNR by connecting a low impedance preamplifier.=C2=A0This technique has b= een used widely and successfully in magnetic resonance imaging ("preamp decoupling").=C2=A0The preamp is designed to have an input impedance that differs largely from the noise-optimum source impedance, so that you can preserve the noise match but create an intentional signal mismatch.
=C2=A0
In practice, you would=C2=A0still=C2=A0want to=C2=A0use a low-= noise FET connected to the high impedance point of a parallel resonant antenna. Normally the gate input impedance (megohms) is=C2=A0higher than the noise optimum (tens of kiloohms), so you would have no preamp damping at all. The trick is=C2=A0then to lower the input impedance by lossless feedback, which has neglegible effect on the noise=C2=A0parameters.
=C2=A0
One configuration is a compromise between common source and common gate circuit configuration ("Zwischenbasisschaltung"), which=C2=A0= can be realised by inserting an additional negative-feedback winding in the source-to-ground path.=C2=A0This is similar to=C2=A0the old=C2=A0regenera= tive audion, but with the feedback coil polarity reversed. Another configuration is parallel feedback from drain to gate, by intentionally increasing the Miller capacitance.

Best regards,
Markus (DF6NM)
-= ----Urspr=C3=BCngliche Mitteilung-----
Von: James Moritz <james.moritz@btopenworl= d.com>
An: rsgb_lf_group <rsgb_lf_group@blackshee= p.org>
Verschickt: Mi, 17 Aug 2011 1:13 am
Betreff: Re: LF: Ferrite RX antennas

Dear Stefan,

Looking good so far...

A Q of 486 is certainly reaching the point where it becomes inconvenient =
-=20
but remember that it is easy to reduce Q (probably connecting a preamp,=20
putting it in a container, etc, will reduce Q a bit anyway), and that the=
=20
higher Q is, the better the SNR. So I would test it as an antenna with a=20
preamp - if there is more SNR than you need, you could experiment with so=
me=20
damping resistance.

Cheers, Jim Moritz
73 de M0BMU=20
--------------020701080105080509020706--